O florescimento é um processo essencial no desenvolvimento vegetal. A mudança de fase vegetativa para reprodutiva em plantas reprograma várias vias genéticas e metabólicas fundamentais para a complementação de seu ciclo de vida. Em Arabidopsis thaliana, modelo mais estudado para o desenvolvimento floral, cinco rotas genéticas são descritas para o controle do florescimento, apresentando redundância de regulação entre essas vias. Dentre essas, a via AGE, regulada pela idade da planta, tem como seu principal efetor o microRNA156 (miR156) e os seus alvos diretos, os fatores de transcrição do tipo SBP/SPL (SQUAMOSA PROMOTER BINDING PROTEIN-like). Em tomateiro (Solanum lycopersicum L.), planta considerada insensível ou pouco responsiva a duas das cinco vias do florescimento (fotoperíodo e vernalização), a via AGE também controla a transição de fase vegetativa para reprodutiva. Plantas de tomateiro superexpressando o miR156 atrasam a transição de fase vegetativa para reprodutiva. Ao contrário, plantas superexpressando o florígeno SINGLE FLOWER TRUSS (SFT) aceleram a mudança de fase vegetativa para reprodutiva. Após curta exposição a baixa temperatura (16°C) o tomateiro também altera o tempo de florescimento, atrasando a transição de fase e prolongando o número de dias até a antese, tanto no cultivar determinado Micro-Tom (MT), quanto no cultivar indeterminado Ailsa Craig. Interessantemente, houve redução de número de folhas nesses cultivares quando expostos a curto período de baixa temperatura (16°C). Entretanto, a diminuição do número de folhas, que está relacionada ao plastochron, pode ter assumido funções específicas em tomateiro que não estão diretamente correlacionadas com o controle do tempo de florescimento em resposta a baixas temperaturas. A baixa oferta do florígeno SFT, em resposta a baixa temperatura, foi necessária para o atraso no tempo de florescimento das plantas, associando sua expressão a via AGE, com regulação da expressão do miR156 e do seu alvo SlSBP15, alterando o acúmulo de seus transcritos no ápice e cotilédones. Em arabidopsis, a redução da expressão de genes SPLs em plantas superexpressando o miR156 resulta em extremo atraso no florescimento e concomitante aumento da produção de folhas em resposta a baixas temperaturas, Em tomateiro, a repressão dos genes SBPs/SPLs em plantas miR156OE também promove atraso no florescimento, mas não afeta a produção de folhas em resposta a baixa temperatura, o que também é observado com o aumento de SFT e plantas p35S::SFT. Além disso, a regulação transcricional, pós-transcricional e possivelmente epigenética de alguns genes da via miR156/SPL/SBP, sugere uma complexa inter-relação entre essa via e a temperatura ambiental em tomateiro. / Flowering is an essential process in plant development. The change from vegetative to reproductive phase in plants reprograms several genetic and metabolic pathways fundamental to the complementation of their life cycle. In Arabidopsis thaliana, the most studied model for floral development, there are five genetic routes described for the control of flowering, which present regulatory redundancy between them. Among these, the AGE pathway, regulated by plant age, has microRNA156 (miR156) as its main effector and the transcription factors SBP/SPL (SQUAMOSA PROMOTER BINDING PROTEIN-like) as its direct targets. In tomato (Solanum lycopersicum L.), plant considered insensitive or not responsive to two of the five flowering pathways (photoperiod and vernalization), the AGE pathway also controls vegetative to reproductive phase transition. Tomato plants overexpressing the miR156 delay the transition from vegetative to reproductive phase. In contrast, plants overexpressing the flowering SINGLE FLOWER TRUSS (SFT) accelerate the vegetative to reproductive phase shift. After short exposure to low temperature (16°C) the tomato also altered the flowering time, delaying the phase transition and extending the number of days until the anthesis, both in the determined Micro-Tom (MT) cultivar and in the indeterminate cultivar Ailsa Craig. Interestingly, there was a reduction in the number of leaves in these cultivars when exposed to a short period of low temperature (16°C). However, the decrease in number of leaves, related to plastochron, may have assumed specific functions in tomatoes that are not directly correlated with the control of flowering time in response to low temperatures. The low supply of the SFT florigen, in response to low temperature, was necessary for the delay in the flowering time of the plants, associating its expression to the AGE path, with regulation of the expression of miR156 and its target SlSBP15, changing the accumulation of its transcripts at the apex and cotyledons. In arabidopsis, the reduction of SPL gene expression in plants overexpressing miR156 results in extreme flowering delay and concomitant increase of leaf production in response to low temperatures. In tomato, repression of SBPs / SPL genes in miR156EE plants also promotes delay in flowering, but does not affect leaf production in response to low temperature, which is also observed with increasing SFT and p35S::SFT plants. In addition, the transcriptional, post-transcriptional and possibly epigenetic regulation of some genes in the miR156 / SPL / SBP pathway suggests a complex interrelationship between this pathway and the environmental temperature in tomato.

No description available.

Cette thèse est dédiée à l'étude des pavages : des ensembles de coloriages du plan discret respectant des contraintes locales données par un jeu de tuiles. Nous nous penchons en particulier sur les liens qui unissent les pavages et la calculabilité. Les pavages étant des ensembles effectivement clos particuliers, nous étudions dans un premier temps la structure des ensembles de degrés Turing des pavages, la comparant à celle des ensembles effectivement clos en général : pour tout ensemble effectivement clos il existe un pavage qui a les même degrés Turing à 0 près, le degré des ensembles récursifs. De plus les pavages ne contenant pas de membre récursif ont une structure particulière : ils contiennent toujours un cône de degrés Turing, un degré Turing et tous les degrés qui lui sont supérieurs. Dans un second temps, nous étudions les ensembles de périodes des pavages, pour diverses notions de périodicité, parvenant à des caractérisations à l'aide de classes de complexité ou de calculabilité pour chaque notion étudiée. Enfin nous nous intéressons à la difficulté calculatoire des problèmes de la factorisation et de la conjugaison, des notions de simulation et d'équivalence adaptées aux spécificités des pavages. / This thesis is dedicated to the study of subshifts of finite type (SFTs) : sets of colorings of the discrete plane which respect some local constraints given by a set of forbidden patterns. We study the links between SFTs and computation. SFTs being specific effectively closed classes, we fist study their Turing degree structure, comparing it to the one of effectively closed classes in general: for any effectively closed class, there exist an SFT having the same Turing degrees except maybe 0, the degree of recursive sets. Furthermore, SFTs containing no recursive member have a particular structure: they always contain a cone of Turing degrees, ie. a Turing degree and all degrees above it. We then study the sets of periods of SFTs, for different notions of periodicity, reaching characterizations by means of computational complexity classes or computability classes for each notion introduced. Finally we look at the computable hardness of the factorization and conjugacy problems, the right notions of simulation and equivalence for SFTs.

La reconstruction 3D d’objets à partir de plusieurs images est un objectif important de la vision par ordinateur. Elle a été largement étudiée pour les objets rigides et non rigides (ou déformables). Le Structure-from-Motion (SfM) est un algorithme qui effectue la reconstruction 3D d’objets rigides en utilisant le mouvement visuel entre plusieurs images obtenues à l’aide d’une caméra en mouvement. Le SfM est une solution très précise et stable. La reconstruction 3D déformable a été largement étudiée pour les images monoculaires (obtenues à partir d’une seule caméra) mais reste un problème ouvert. Les méthodes actuelles exploitent des indices visuels tels que le mouvement visuel inter-image et l’ombrage afin de construire un algorithme de reconstruction. Cette thèse se concentre sur l’utilisation du mouvement visuel inter-image pour résoudre ce problème. Deux types de scénarios existent dans la littérature : 1) le Non-Rigid Structure-from-Motion (NRSfM) et 2) le Shape-from-Template (SfT). L’objectif du NRSfM est de reconstruire plusieurs formes d’un objet déformable tel qu’il apparaît dans plusieurs images, alors que le SfT (également appelé reconstruction à partir d’un modèle de référence) utilise une seule image d’un objet déformé et son modèle 3D de référence (une forme 3D texturée de l’objet dans une configuration) pour estimer la forme déformée de l’objet. (...) / Reconstructing the 3D shape of objects from multiple images is an important goal in computer vision and has been extensively studied for both rigid and non-rigid (or deformable) objects. Structure-from-Motion (SfM) is an algorithm that performs the 3D reconstruction of rigid objects using the inter-image visual motion from multiple images obtained from a moving camera. SfM is a very accurate and stable solution. Deformable 3D reconstruction, however, has been widely studied for monocular images (obtained from a single camera) and still remains an open research problem. The current methods exploit visual cues such as the inter-image visual motion and shading in order to formalise a reconstruction algorithm. This thesis focuses on the use of the inter-image visual motion for solving this problem. Two types of scenarios exist in the literature: 1) Non-Rigid Structure-from-Motion (NRSfM) and 2) Shape-from-Template (SfT). The goal of NRSfM is to reconstruct multiple shapes of a deformable object as viewed in multiple images while SfT (also referred to as template-based reconstruction) uses a single image of a deformed object and its 3D template (a textured 3D shape of the object in one configuration) to recover the deformed shape of the object. We propose an NRSfM method to reconstruct the deformable surfaces undergoing isometric deformations (the objects do not stretch or shrink under an isometric deformation) using Riemannian geometry. This allows NRSfM to be expressed in terms of Partial Differential Equations (PDE) and to be solved algebraically. We show that the problem has linear complexity and the reconstruction algorithm has a very low computational cost compared to existing NRSfM methods. This work motivated us to use differential geometry and Cartan’s theory of connections to model NRSfM, which led to the possibility of extending the solution to deformations other than isometry. In fact, this led to a unified theoretical framework for modelling and solving both NRSfM and SfT for various types of deformations. In addition, it also makes it possible to have a solution to SfT which does not require an explicit modelling of deformation. An important point is that most of the NRSfM and SfT methods reconstruct the thin-shell surface of the object. The reconstruction of the entire volume (the thin-shell surface and the interior) has not been explored yet. We propose the first SfT method that reconstructs the entire volume of a deformable object.

Inconel alloys are commonly used as structural materials in nuclear reactors. One of these alloys, the Inconel X-750, is a γ’ Ni3(Al, Ti) strengthened superalloy extensively used in the cores of reactors, such as spacers in CANada Deuterium Uranium (CANDU) fuel channels. Prior to their application in commercial reactors, accelerated irradiation tests had been conducted in liquid metal fast reactors. Results did not indicate any problem stemming from significant fast neutron irradiation. However, recently it has been found that the ex-service CANDU Inconel X-750 spacers became severely brittle after a lengthy exposure to reactor environment. The underlying mechanism remains unclear and thus forms the focus of this current investigation, predominantly through transmission electron microscopy (TEM). This dissertation unfolds with the literature review in Chapter 2, followed by presentation of novel techniques in Chapter 3 on the preparation of TEM samples from small reactor components, namely the spacers. Chapter 4 presents TEM characterizations of ex-service spacers removed from the reactors. To simulate neutron irradiation over wide temperature range in an effort to understand the damage mechanisms, heavy ion irradiations were conducted and reported in Chapter 5 and 6. Irradiations are found to significantly alter the stability of the primary strengthening phase γ’, a systematic experimental study of which is presented in Chapter 7. To fully understand the effects of transmutation produced helium on irradiation induced cavity and dislocation microstructures, TEM in-situ heavy ion irradiations with hot/cold pre-injected helium were conducted and reported in Chapter 8 and 9. Helium was found to play an important role in the irradiation-induced instability of γ’ in nickel-based superalloys, the discussion of which is presented in Chapter 10. As one of the most important defect structures induced from irradiation, the stacking-fault-tetrahedra, were dynamically observed and are described in a journal manuscript in Appendix A. In addition to broadening current understanding of material degradation mechanism for in-service CANDU spacer, this study also provides comprehensive information on irradiation damage in nickel based superalloys, irradiation induced lattice defects and phase instability in face centered cubic alloys, as well as helium’s effects on cavity formation, dislocation evolution, and phase transformation. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2013-09-06 15:21:02.334

No description available.

Os solos brasileiros apresentam baixa disponibilidade de fósforo (P). Devido à natureza mineralógica desses solos, a adubação é uma tarefa difícil, em função dos processos de adsorção específica e precipitação, que causam baixa recuperação do P aplicado. Os fertilizantes totalmente acidulados (FTA), com praticamente todo P solúvel em água, são as fontes mais utilizadas no Brasil. Porém, a utilização dessas fontes, pode não ser o mais indicado para esses solos. Teoricamente, o fertilizante fosfatado ideal possibilitaria suprir a demanda inicial da planta, apresentando ainda liberação lenta durante o ciclo da cultura, resultando em cinética de liberação do P mais ajustada a demanda das culturas. Com base nessa premissa, objetivou-se com esse trabalho avaliar a eficiência de fertilizantes fosfatados produzidos por meio da mistura no mesmo grânulo de FTA, fosfato natural reativo de Bayóvar (FN) e enxofre elementar (S0). Os fertilizantes foram avaliados em experimentos de incubação, casa de vegetação e campo. O estudo de incubação foi conduzido com objetivo de avaliar a difusão, disponibilidade e produtos de reação do P e S dos fertilizantes: fosfato monoamônico (MAP), superfosfato triplo (SFT) e MES (MicroEssentials®); e os fertilizantes produzidos: MAP+FN, MAP+FN+S0[2:1], MAP+FN+S0[1:1], SFT+FN e SFT+FN+S0[2:1], obtidos por meio da granulação dos FTA com o FN, na relação 1:1, com base no P total das fontes, com ou sem adição de S0 na composição. Os fertilizantes produzidos com MAP proporcionaram maiores difusões e disponibilidade do P, do que os fertilizantes com SFT. O S0 melhorou a difusão e disponibilidade do P dos fertilizantes produzidos, principalmente nos fertilizantes contendo MAP. Dois experimentos foram conduzidos em casa de vegetação, destacando-se como objetivos principais: estudar a proporção entre os FTA o FN e a presença do S0 na mistura; quantificar o efeito do S0 no aumento da absorção de P do FN, utilizando o 32P e avaliar os fertilizantes com S0 na composição em fornecer S para a cultura do milho, comparando-os com fertilizantes comerciais. Nos fertilizantes com 50% de MAP ou SFT, o aumento na absorção de P dos fertilizantes em função da adição do S0 foi de 26 e 18%, respectivamente. Os fertilizantes com S0 na composição foram menos eficientes no fornecimento de S para o milho do que o S0 aplicado em pó, mas, foram mais eficientes do que o fertilizante contendo S0 pastilhado com bentonita. O estudo de campo foi conduzido com a cultura da soja em um Latossolo Vermelho na região do Cerrado, município de Itiquira-MT. Os fertilizantes avaliados foram: MAP, FN, MAP+FN, MAP+FN+S0[2:1] e MAP+FN+S0[1:1], aplicados a lanço e localizado. Os fertilizantes MAP+FN[2:1] e MAP+FN[1:1] obtiveram eficiência agronômica superior à do MAP+FN e semelhantes à do MAP. Os fertilizantes produzidos com S0 na composição apresentam potencial para serem utilizados na agricultura, podendo ser fontes alternativas aos FTA, ainda com fornecimento de S. Este foi provavelmente o primeiro estudo de campo utilizando essa associação. Outros estudos, em outras condições de solo e clima, devem ser realizados para confirmar a viabilidade do uso dessas fontes. / Brazilian soils has low phosphorus (P) availability. Due to the mineralogical composition of these soils, fertilization is a challenge, because of the specific adsorption and precipitation processes, causing low P recovery from fertilizers. Fully acidulated P fertilizers (FAP), practically with all P soluble in water, are the most used sources in Brazil. However, they may not be the most appropriate sources for these soils. Theoretically, the ideal phosphate fertilizer would be the one which supplies the initial plant demand as well as releases slowly P during the crop cycle, allowing better synchronization between the plant demand and dissolution of P source. Based on this premise, the aim of this study was to evaluate the efficiency of phosphate fertilizers produced by mixture of FAP, Bayóvar phosphate rock (PR) and elemental sulfur (S0) in the same granule. The fertilizers were evaluated in incubation, greenhouse and field trials. The incubation study was carried out to evaluate the diffusion, availability and reaction products of P and S from the fertilizers: monoammonium phosphate (MAP), triple superphosphate (TSP) and MES (MicroEssentials®); and the produced fertilizers: MAP+PR, MAP+PR+S0[2:1], MAP+PR+S0[1:1], TSP+PR and TSP+PR+S0[2:1], obtained by granulation of FAP with PR in the ratio 1:1, based on total P content, with or without S0 in the composition. Fertilizers with MAP in the composition resulted in better P diffusion and availability than the fertilizers with TSP. The S0 improved the P diffusion and availability mainly from fertilizers produced with MAP. Two experiments were carried out in greenhouse, with the objectives to: study the FAP and PR ratio and S0 presence in the mixture; quantify the S0 effect for increasing the P uptake from PR, using 32P; and evaluate the fertilizers with S0 in the composition to provide sulfur (S) for maize, comparing them with commercial sources. The S0 presence in the granule improved the P uptake on 26 and 18% from the fertilizers produced with 50 % from MAP or TSP, respectively. The fertilizers with S0 in the composition were less efficient than powdered S0 providing S to maize, but they were better than commercial fertilizer with bentonite+S0. The field trial was carried out with soybean in an Oxisol in Cerrado region, Itiquira-MT. The fertilizers evaluated were: MAP, PR, MAP+PR, MAP+PR+S0[2:1] and MAP+PR+S0[1:1] applied in band or broadcast. The fertilizers MAP+PR+S0[2:1] and MAP+PR+S0[1:1] were better than MAP+PR and similar to MAP on soybean yield and agronomic efficiency. Fertilizers produced by MAP+PR and S0 in the same granule can be potential sources to be used in agriculture, could be alternative sources for FAP, moreover can supply S to crops. Probably this was the first study using the abovementioned association. Other studies in others soils and weather conditions should be carried out to confirm the potential use of these sources.

Os solos brasileiros apresentam baixa disponibilidade de fósforo (P). Devido à natureza mineralógica desses solos, a adubação é uma tarefa difícil, em função dos processos de adsorção específica e precipitação, que causam baixa recuperação do P aplicado. Os fertilizantes totalmente acidulados (FTA), com praticamente todo P solúvel em água, são as fontes mais utilizadas no Brasil. Porém, a utilização dessas fontes, pode não ser o mais indicado para esses solos. Teoricamente, o fertilizante fosfatado ideal possibilitaria suprir a demanda inicial da planta, apresentando ainda liberação lenta durante o ciclo da cultura, resultando em cinética de liberação do P mais ajustada a demanda das culturas. Com base nessa premissa, objetivou-se com esse trabalho avaliar a eficiência de fertilizantes fosfatados produzidos por meio da mistura no mesmo grânulo de FTA, fosfato natural reativo de Bayóvar (FN) e enxofre elementar (S0). Os fertilizantes foram avaliados em experimentos de incubação, casa de vegetação e campo. O estudo de incubação foi conduzido com objetivo de avaliar a difusão, disponibilidade e produtos de reação do P e S dos fertilizantes: fosfato monoamônico (MAP), superfosfato triplo (SFT) e MES (MicroEssentials®); e os fertilizantes produzidos: MAP+FN, MAP+FN+S0[2:1], MAP+FN+S0[1:1], SFT+FN e SFT+FN+S0[2:1], obtidos por meio da granulação dos FTA com o FN, na relação 1:1, com base no P total das fontes, com ou sem adição de S0 na composição. Os fertilizantes produzidos com MAP proporcionaram maiores difusões e disponibilidade do P, do que os fertilizantes com SFT. O S0 melhorou a difusão e disponibilidade do P dos fertilizantes produzidos, principalmente nos fertilizantes contendo MAP. Dois experimentos foram conduzidos em casa de vegetação, destacando-se como objetivos principais: estudar a proporção entre os FTA o FN e a presença do S0 na mistura; quantificar o efeito do S0 no aumento da absorção de P do FN, utilizando o 32P e avaliar os fertilizantes com S0 na composição em fornecer S para a cultura do milho, comparando-os com fertilizantes comerciais. Nos fertilizantes com 50% de MAP ou SFT, o aumento na absorção de P dos fertilizantes em função da adição do S0 foi de 26 e 18%, respectivamente. Os fertilizantes com S0 na composição foram menos eficientes no fornecimento de S para o milho do que o S0 aplicado em pó, mas, foram mais eficientes do que o fertilizante contendo S0 pastilhado com bentonita. O estudo de campo foi conduzido com a cultura da soja em um Latossolo Vermelho na região do Cerrado, município de Itiquira-MT. Os fertilizantes avaliados foram: MAP, FN, MAP+FN, MAP+FN+S0[2:1] e MAP+FN+S0[1:1], aplicados a lanço e localizado. Os fertilizantes MAP+FN[2:1] e MAP+FN[1:1] obtiveram eficiência agronômica superior à do MAP+FN e semelhantes à do MAP. Os fertilizantes produzidos com S0 na composição apresentam potencial para serem utilizados na agricultura, podendo ser fontes alternativas aos FTA, ainda com fornecimento de S. Este foi provavelmente o primeiro estudo de campo utilizando essa associação. Outros estudos, em outras condições de solo e clima, devem ser realizados para confirmar a viabilidade do uso dessas fontes. / Brazilian soils has low phosphorus (P) availability. Due to the mineralogical composition of these soils, fertilization is a challenge, because of the specific adsorption and precipitation processes, causing low P recovery from fertilizers. Fully acidulated P fertilizers (FAP), practically with all P soluble in water, are the most used sources in Brazil. However, they may not be the most appropriate sources for these soils. Theoretically, the ideal phosphate fertilizer would be the one which supplies the initial plant demand as well as releases slowly P during the crop cycle, allowing better synchronization between the plant demand and dissolution of P source. Based on this premise, the aim of this study was to evaluate the efficiency of phosphate fertilizers produced by mixture of FAP, Bayóvar phosphate rock (PR) and elemental sulfur (S0) in the same granule. The fertilizers were evaluated in incubation, greenhouse and field trials. The incubation study was carried out to evaluate the diffusion, availability and reaction products of P and S from the fertilizers: monoammonium phosphate (MAP), triple superphosphate (TSP) and MES (MicroEssentials®); and the produced fertilizers: MAP+PR, MAP+PR+S0[2:1], MAP+PR+S0[1:1], TSP+PR and TSP+PR+S0[2:1], obtained by granulation of FAP with PR in the ratio 1:1, based on total P content, with or without S0 in the composition. Fertilizers with MAP in the composition resulted in better P diffusion and availability than the fertilizers with TSP. The S0 improved the P diffusion and availability mainly from fertilizers produced with MAP. Two experiments were carried out in greenhouse, with the objectives to: study the FAP and PR ratio and S0 presence in the mixture; quantify the S0 effect for increasing the P uptake from PR, using 32P; and evaluate the fertilizers with S0 in the composition to provide sulfur (S) for maize, comparing them with commercial sources. The S0 presence in the granule improved the P uptake on 26 and 18% from the fertilizers produced with 50 % from MAP or TSP, respectively. The fertilizers with S0 in the composition were less efficient than powdered S0 providing S to maize, but they were better than commercial fertilizer with bentonite+S0. The field trial was carried out with soybean in an Oxisol in Cerrado region, Itiquira-MT. The fertilizers evaluated were: MAP, PR, MAP+PR, MAP+PR+S0[2:1] and MAP+PR+S0[1:1] applied in band or broadcast. The fertilizers MAP+PR+S0[2:1] and MAP+PR+S0[1:1] were better than MAP+PR and similar to MAP on soybean yield and agronomic efficiency. Fertilizers produced by MAP+PR and S0 in the same granule can be potential sources to be used in agriculture, could be alternative sources for FAP, moreover can supply S to crops. Probably this was the first study using the abovementioned association. Other studies in others soils and weather conditions should be carried out to confirm the potential use of these sources.