Student Number : 0206926T - PhD thesis - School of Geography, Archaeology and Environmental Studies - Faculty of Science / The overarching objective of this thesis is to determine causes of food insecurity in southern Africa, and how it can best be addressed. This objective is addressed through a number of research questions and methods at three geographic scales: the regional, through a technique of meta-analysis which is used to synthesise 49 local-level household economy case studies; the provincial, through a Delphi panel of practitioner experience; and the local, using multiple research techniques, including participatory methods. An extremely diverse range of factors contributing to food-insecurity are found at all three scales, indicating that community- and household-specific dynamics give rise to forms of food insecurity. Two common processes, however, are argued to be common across all the casestudy communities in the regional-scale research. These are the closely related processes of cycles of intensifying vulnerability associated with livelihood ‘trade-offs’, and of communitylevel social capital changing into forms that undermine resilience to food insecurity - such as the decline in two-parent families. A further probing of social capital at the local level suggests that while social capital takes multiple forms, and further remains in many respects a problematic concept, it nevertheless provides a valuable lens through which powerful social dynamics might be examined in developing responses to food insecurity. Policy makers and change agents should carefully consider their role in building community social-capital that might enhance the ability of vulnerable communities to overcome livelihood constraints and adapt to the tremendous challenges posed by changing economic environments in southern Africa. Drawing on the research at all scales, a framework is provided that calls for a reconceptualisation of food-security interventions to focus on intervention processes, applicable at all scales and in all contexts across the region. The development of social capital, participation, co-ordination and learning interactions are explored as central elements in these processes. The framework asks for closer attention to both the appropriate mechanisms (such as policy) necessary to effect change, and the human dimensions that give these mechanisms agency. The findings of the thesis represent an additional shift in understanding food security to acknowledge that the value of a political economic interpretation of food security is limited independent of an understanding of the cross-scale social networks and relational interactions that ultimately configure and reconfigure it.

Being in the era of Big data, the applicability and importance of data-driven models like artificial neural network (ANN) in the modern statistics have increased substantially. In this dissertation, our main goal is to contribute to the development and the expansion of these ANN models by incorporating Bayesian learning techniques. We have demonstrated the applicability of these Bayesian ANN models in interdisciplinary research including health and cybersecurity. Breast cancer is one of the leading causes of deaths among females. Early and accurate diagnosis is a critical component which decides the survival of the patients. Including the well known ``Gail Model", numerous efforts are being made to quantify the risk of diagnosing malignant breast cancer. However, these models impose some limitations on their use of risk prediction. In this dissertation, we have developed a diagnosis model using ANN to identify the potential breast cancer patients with their demographic factors and the previous mammogram results. While developing the model, we applied the Bayesian regularization techniques (evidence procedure), along with the automatic relevance determination (ARD) prior, to minimize the network over-fitting. The optimal Bayesian network has 81\% overall accuracy in correctly classifying the actual status of breast cancer patients, 59\% sensitivity in accurately detecting the malignancy and 83\% specificity in correctly detecting non-malignancy. The area under the receiver operating characteristic curve (0.7940) shows that this is a moderate classification model. We then present a new Bayesian ANN model for developing a nonlinear Poisson regression model which can be used for count data modeling. Here, we have summarized all the important steps involved in developing the ANN model, including the forward-propagation, backward-propagation and the error gradient calculations of the newly developed network. As a part of this, we have introduced a new activation function into the output layer of the ANN and error minimizing criterion, using count data. Moreover, we have expanded our model to incorporate the Bayesian learning techniques. The performance our model is tested using simulation data. In addition to that, a piecewise constant hazard model is developed by extending the above nonlinear Poisson regression model under the Bayesian setting. This model can be utilized over the other conventional methods for accurate survival time prediction. With this, we were able to significantly improve the prediction accuracies. We captured the uncertainties of our predictions by incorporating the error bars which could not achieve with a linear Poisson model due to the overdispersion in the data. We also have proposed a new hybrid learning technique, and we evaluated the performance of those techniques with a varying number of hidden nodes and data size. Finally, we demonstrate the suitability of Bayesian ANN models for time series forecasting by using an online training algorithm. We have developed a vulnerability forecast model for the Linux operating system by using this approach.

[pt] As zonas costeiras, de um modo geral, estão entre as áreas de maior risco no contexto da mudança climática, devido à concentração de ecossistemas importantes e recursos naturais típicos dessas áreas. Essas regiões abrigam uma grande parcela da população global em metrópoles urbanas, juntamente com uma concentração de estruturas críticas, como as indústrias portuárias, definindo uma alta exposição a ameaças incidentes. Devido à sua localização, as regiões litorâneas são afetadas por eventos críticos como a subida do nível do mar e outros fenômenos climáticos. Eventos de natureza extrema, como ciclones e tempestades costeiras, que somados à variação de marés podem causar ressacas e ondas gigantes. Tais eventos podem impactar essas áreas como erosão costeira, inundações, intrusão salina em corpos hídricos e desequilíbrio dos ecossistemas. A combinação dessas ameaças com o alto grau de exposição e a condição de vulnerabilidade de muitas das cidades litorâneas, pode resultar em perdas e danos relevantes. Esse alto risco define a importância de estudos sobre a vulnerabilidade de cidades costeiras nos dias atuais. Este estudo apresenta o resumo dos conceitos associados à mudança climática, vulnerabilidade e resiliência que foi baseado em uma análise crítica da literatura. Além disso, propõe uma estratégia metodológica para avaliar a vulnerabilidade climática de áreas urbanas costeiras, considerando tanto a população como os bens que estão em risco. A ferramenta de metodologia desenvolvida apresenta matrizes conceituais e inter-relações entre variáveis e indicadores. A integração de dimensões físicas e socioeconômicas, assim como as infraestruturas, instalações básicas e da capacidade de adaptação, permite aplicação deste método utilizando os dados selecionados para definição de prioridades nas políticas públicas. / [en] Coastal areas, in general, are among the areas most at risk in the context of climate change, due to the concentration of important ecosystems and natural resources typical of these areas. These regions house a large portion of the global population in urban metropolises, along with a concentration of critical structures, such as industrial ports, defining a high exposure to incident threats. Due to their location, coastal regions are affected by critical events such as sea level rise and other climate phenomena. Events of an extreme nature, such as cyclones and coastal storms, which, combined with tidal variations, can cause undertows and giant waves. Such events can impact these areas such as coastal erosion, flooding, saline intrusion into water bodies and imbalance of ecosystems. The combination of these threats with the high degree of exposure and the vulnerable condition of many coastal cities can result in significant losses and damages. This high risk defines the importance of studies on the vulnerability of coastal cities today. This study presents a summary of the concepts associated with climate change, vulnerability and resilience that was based on a critical analysis of the literature. Furthermore, it proposes a methodological strategy to assess the climate vulnerability of coastal urban areas, considering both the population and the assets that are at risk. The methodology tool developed presents conceptual matrices and interrelationships between variables and indicators. The integration of physical and socioeconomic dimensions, as well as infrastructure, basic facilities and adaptation capacity, allows the application of this method using selected data to define priorities in public policies

[pt] Pobreza, fome e insegurança alimentar, analfabetismo e baixa escolaridade, condições precárias de moradia e assistência médica inadequada caracterizam as condições de vida de milhares de famílias em todo o mundo. Em um cenário de recursos limitados, um pré-requisito para a tomada de decisão é entender as vulnerabilidades da população afetada para que seja possível priorizar as áreas/famílias/pessoas mais carentes. Entre os vários critérios de priorização, a equidade emergiu como um critério-chave, conceituada em termos de justiça na alocação e distribuição de benefícios. A presente tese propõe incorporar questões de priorização e equidade em modelos de tomada de decisão para políticas públicas voltadas para populações vulneráveis. Estruturamos uma abordagem que integra meios de medir a vulnerabilidade como forma de priorização (através do desenvolvimento de índices de priorização) e incorporando-os a um modelo de tomada de decisão para otimizar a alocação e distribuição de recursos de forma eficaz, e principalmente, equitativa. Para lançar luz sobre esse problema, estudamos dois casos reais e complexos, aplicados no cenário de doenças endêmicas e no contexto de fome e insegurança alimentar no Brasil. / [en] Poverty, hunger and food insecurity, illiteracy and low education, poor housing conditions, and inadequate health care describe the living conditions of thousands of families worldwide. In a scenario of limited resources, a prerequisite for decision-making is to understand the vulnerabilities of the affected population so that it is possible to target and prioritize the most in-need areas/households/people. Among the numerous prioritization criteria, equity has emerged as a key criterion conceptualized in terms of fairness in allocating and distributing benefits and burdens in society. This thesis proposes to incorporate prioritization and equity issues into decision-making models for orientated vulnerable populations public policies. We structure an approach that integrates means of measuring vulnerability as a way of prioritization (through developing prioritization indexes) and incorporating them into a decision-making model to optimize resource allocation and distribution effectively and especially equitably. To shed light on this problem, we study two real and complex cases applied in the malaria intervention context and hunger and food insecurity scenario in Brazil.

La zone sahélienne a connu une baisse des précipitations et d’importants changements d'utilisation des terres ces dernières décennies qui ont conduit à une forte régression du couvert ligneux. Pourtant, Guiera senegalesis J.F. Gmel est une Combretaceae semi-sempervirente, dont la dominance s'est accrue avec la pression agricole dans la bande soudano-sahélienne où elle joue un rôle socio-économique et agroforestier important. Elle constitue donc un bon modèle pour étudier les réponses hydriques du couvert ligneux actuel à la sécheresse et les modifications de ces réponses sous l'effet de la coupe.Les objectifs de ce travail de thèse étaient : 1) de caractériser et quantifier les processus de régulation hydrique chez G. senegalensis et de déterminer ses limites fonctionnelles, afin d’estimer sa marge de sécurité dans ses conditions actuelles de croissance, 2) d’estimer l’effet de la coupe annuelle sur ses processus de régulation et 3) d’analyser les variations de ses traits foliaires en fonction de la saison et des conditions de croissance.Les mesures et les observations ont été réalisées d’avril 2009 à février 2011 sur une jachère âgée, sur une jeune jachère et sur deux champs de mil adjacents aux deux jachères respectivement. A l'échelle de l'arbuste, le potentiel hydrique foliaire et la conductance stomatique ont été mesurés au cours de ces deux saisons de croissance sur un échantillon d'arbustes dans les trois types de couvert. Le taux de transpiration foliaire et la conductance hydraulique sol-feuille en ont été déduits. A l’échelle du rameau, ont été suivi la dynamique du nombre de feuilles, de la surface moyenne des feuilles, du diamètre moyen des tiges qui les portent. La durée de vie moyenne des feuilles et leur masse surfacique ont été mesurées. La courbe de vulnérabilité à la cavitation de l'espèce, qui est la perte de la conductivité hydraulique en fonction du potentiel hydrique, a été réalisée à partir de plusieurs segments de branches passés au CAVITRON en laboratoire.Les principaux résultats obtenus sont que la fermeture des stomates qui permet à l’espèce de réguler ses pertes en eau a lieu à un niveau faible de cavitation du xylème (30%). Ainsi, l’espèce peut survivre dans les conditions sahéliennes grâce à une « marge de sécurité » positive de +0,6 MPa. La régulation stomatique couplée à un ajustement foliaire permet à l’espèce de maintenir son équilibre hydrique au cours de la saison sèche chez les arbustes matures non perturbés. La baisse des potentiels hydriques foliaires de base et minimum en réponse à la sécheresse saisonnière est isohydrodynamique et est plus élevé chez les arbustes matures, suggérant que les repousses de l'année sont moins stressées. De plus, la coupe a pour effet de découpler l’ajustement foliaire de la régulation stomatique et entraîne une production de feuilles et une croissance des jeunes rameaux continues tout au long de l'année chez les repousses, grâce à une conductance hydraulique sol-feuille deux fois plus élevée que chez les arbustes matures. Enfin, la durée de vie des feuilles s’allonge avec l’âge des rameaux d'une année comme avec l'âge du peuplement, tandis que la masse surfacique foliaire augmente progressivement de la même façon quand on passe de la saison des pluies à la saison sèche, quel que soit l'âge du peuplement.Ces traits fonctionnels contribuent à ce que l’espèce puisse à la fois résister aux conditions de sécheresse dans lesquelles elle croît et ré-allouer de façon intense des ressources, stockées probablement dans les racines, à la reconstruction rapide de sa partie aérienne à la suite d'une coupe. Les limites d'une telle stratégie restent cependant à identifier, en particulier le seuil d'épuisement des ressources sous l'effet de la répétition annuelle des coupes. / Sahel suffered from severe rainfall decreases combined to great changes in land use during the last decades that led to strong decrease in the woody cover. However, Guiera senegalesis J.F. Gmel is a semi-evergreen Combretaceae whose dominance rose with crop pressure in the Sudano-Sahelian band where it plays an important socio-economic role through agroforestry. Consequently, this is a good model to study hydric responses of the present woody cover to drought and the effect of cutting on these responses.The aims of this work were: 1) to characterize and quantify hydric regulation processes in G. senegalesis and to determine its specific functional limits, in order to estimate its safety margin in its current growth conditions, 2) to estimate cut effect on these processes and 3) to analyze variations of its leaf traits according to the season and its specific growth conditions.Measurements and observations were conducted from April 2009 to February 2011 on an old fallow, on a young fallow, and on the two crop fields adjacent to the two fallows respectively. At the shrub scale, leaf water potential and stomatal conductance were measured during the two growing seasons on shrub samples in the three cover type. The leaf transpiration rate and the soil-to-leaf conductivity were deduced. At the stem scale, the dynamics of the number of leaves, the mean leaf area (LMA), the mean diameter of the stems that carry them, the mean leaf life span, and the leaf mass per area were monitored. The species vulnerability curve to cavitation, which is the loss of conductivity as a function of the water potential, was obtained from several peaces of branches treated in a CAVITRON at the laboratory.The main results obtained were that the stomatal closure that allows species to regulate its water loss occurs at a low rate of xylem cavitation (30%). Thus, the species can survive in its Sahelian conditions thanks to a positive “safety margin” of +0.6 MPa. Stomatal regulation coupled with leaf adjustment allows the species to maintain its water balance during the dry season in mature and undisturbed shrubs. The decrease in predawn and midday leaf water potentials in response to seasonal drought was isohydrodynamic, and it was greater in mature shrubs, suggesting that current year resprouts are under less stress. In addition, cutting decouple leaf adjustment from stomatal regulation, leading to continuous leaf production and young stem growth all over the year, thanks to a soil-to-leaf conductivity seven times higher in the current year's resprouts than in the mature shrubs. Finally, leaf life span increases with the current year's stem age as well as with the stand age, while the LMA progressively increases from the rainy season to the dry season, similarly whatever the stand age.These functional traits contribute to the species resistance to the drought conditions under which it grows, but also, following the cutting, to intensively re-allocate resources, probably from the root reserve, to the fast re-building of the aerial part. However, the limits of such a strategy remain to be identified, especially the resource exhaustion threshold under repetitive yearly cutting.

[pt] Atualmente, temas como mudanças climáticas e desastres naturais têm sido pauta central nos debates urbanos. Nesse sentido, determinou-se como objetivo geral do trabalho investigar os processos referentes à distribuição do risco e à vulnerabilidade socioambiental dentro do limite municipal de Três Rios, RJ. A escolha desse município como estudo de caso justifica-se pela frequência com que episódios de alagamento, enchentes e inundações, em períodos de chuvas intensas, têm assolado a região. Para a investigação proposta, a metodologia utilizada consistiu em entender o processo de formação do risco como um ponto de intersecção entre os conceitos de geossistema e formação socioespacial. Isso implicou na revisão sistemática de bibliografias relacionadas aos temas e de documentos oficiais como os planos diretores municipais. Essa investigação foi embasada tanto em dados obtidos de forma primária, por meio de trabalhos de campo para realizar análises da paisagem geomorfológica e entrevistas semiestruturadas com a população; quanto de forma secundária, obtidos no censo do IBGE (2010), INMET, Mapbiomas e outros. A pesquisa apontou que o risco é produzido socialmente e, ao se tratar de alagamentos, inundações e enchentes no tecido urbano, a produção desigual do espaço protagoniza o cenário. Nesse sentido, destacam-se os fenômenos de urbanização, o desenvolvimento do município sem o planejamento adequado e a especulação imobiliária acrescida de um processo de periferização/favelização da classe trabalhadora, o qual apresenta impactos econômicos, sociais e ambientais para a população. Ademais, as entrevistas apontaram que o poder público municipal tem muito a fazer no que diz respeito aos macroprocessos que envolvem a gestão dos riscos: o município necessita focar em políticas de base que atuem na raiz do problema. / [en] Currently, topics such as climate change and natural disasters have been a central topic in urban debates. In this sense, the general objective of the work was determined to investigate the processes relating to the distribution of risk and socio-environmental vulnerability within the municipal limit of Três Rios-RJ. The choice of this municipality as a case study is justified by the high frequency with which episodes of flooding, floods and floods, during periods of intense rain, have ravaged the region. For the proposed investigation, the methodology used consisted of understanding the risk formation process as a point of intersection between the concepts of geosystem and socio-spatial formation, which implied a systematic review of bibliographies related to the themes and official documents such as master plans municipalities. This investigation was based both on data obtained primarily, through fieldwork to carry out analyzes of the geomorphological landscape and semi-structured interviews with the population, and secondary, obtained from the census of IBGE (2010), INMET, Mapbiomas and others. The research showed that the risk is socially produced and when dealing with floods, floods and floods in the urban fabric, the unequal production of space plays a leading role. In this sense, the phenomena of urbanization stand out, the development of the municipality without adequate planning, real estate speculation plus a process of peripheralization/slumization of the working class, which have economic, social and environmental impacts on the population. Furthermore, the interviews showed that the municipal government still has a lot to do with regard to the macro processes that involve risk management, showing that the municipality needs to focus on basic policies that act at the root of the problem.