Résumé : Les photodiodes à avalanche monophotonique (SPAD) sont d'intérêts pour les applications requérant la détection de photons uniques avec une grande résolution temporelle, comme en physique des hautes énergies et en imagerie médicale. En fait, les matrices de SPAD, souvent appelés photomultiplicateurs sur silicium (SiPM), remplacent graduellement les tubes photomultiplicateurs (PMT) et les photodiodes à avalanche (APD). De plus, il y a une tendance à utiliser les matrices de SPAD en technologie CMOS afin d'obtenir des pixels intelligents optimisés pour la résolution temporelle. La fabrication de SPAD en technologie CMOS commerciale apporte plusieurs avantages par rapport aux procédés optoélectroniques comme le faible coût, la capacité de production, l'intégration d'électronique et la miniaturisation des systèmes. Cependant, le défaut principal du CMOS est le manque de flexibilité de conception au niveau de l'architecture du SPAD, causé par le caractère fixe et standardisé des étapes de fabrication en technologie CMOS. Un autre inconvénient des matrices de SPAD CMOS est la perte de surface photosensible amenée par la présence de circuits CMOS. Ce document présente la conception, la caractérisation et l'optimisation de SPAD fabriqués dans une technologie CMOS commerciale (Teledyne DALSA 0.8µm HV CMOS - TDSI CMOSP8G). Des modifications de procédé sur mesure ont été introduites en collaboration avec l'entreprise CMOS pour optimiser les SPAD tout en gardant la compatibilité CMOS. Les matrices de SPAD produites sont dédiées à être intégrées en 3D avec de l'électronique CMOS économique (TDSI) ou avec de l'électronique CMOS submicronique avancée, produisant ainsi un SiPM 3D numérique. Ce SiPM 3D innovateur vise à remplacer les PMT, les APD et les SiPM commerciaux dans les applications à haute résolution temporelle. L'objectif principal du groupe de recherche est de développer un SiPM 3D avec une résolution temporelle de 10 ps pour usage en physique des hautes énergies et en imagerie médicale. Ces applications demandent des procédés fiables avec une capacité de production certifiée, ce qui justifie la volonté de produire le SiPM 3D avec des technologies CMOS commerciales. Ce mémoire étudie la conception, la caractérisation et l'optimisation de SPAD fabriqués en technologie TDSI-CMOSP8G. / Abstract : Single Photon Avalanche Diodes (SPAD) generate much interest in applications which require single photon detection and excellent timing resolution, such as high energy physics and medical imaging. In fact, SPAD arrays such as Silicon PhotoMultipliers (SiPM) are gradually replacing PhotoMultiplier Tubes (PMT) and Avalanche PhotoDiodes (APD). There is now a trend moving towards SPAD arrays in CMOS technologies with smart pixels control for high timing demanding applications. Making SPAD in commercial CMOS technologies provides several advantages over optoelectronic processes such as lower costs, higher production capabilities, easier electronics integration and system miniaturization. However, the major drawback is the lack of flexibility when designing the SPAD architecture because all fabrication steps are fixed by the CMOS technology used. Another drawback of CMOS SPAD arrays is the loss of photosensitive areas caused by the CMOS circuits integration. This document presents SPAD design, characterization and optimization made in a commercial CMOS technology (Teledyne DALSA 0.8 µm HV CMOS - TDSI CMOSP8G). Custom process variations have been performed in partnership with the CMOS foundry to optimize the SPAD while keeping the CMOS line compatibility. The realized SPAD and SPAD arrays are dedicated to 3D integration with either low-cost TDSI CMOS electronics or advanced deep sub-micron CMOS electronics to perform a 3D digital SiPM (3D-SiPM). The novel 3D-SiPM is intended to replace PMT, APD and commercially available SiPM in timing demanding applications. The group main objective is to develop a 10 ps timing resolution 3D-SiPM for use in high energy physics and medical imaging applications. Those applications require reliable technologies with a certified production capability, which justifies the actual effort to use commercial CMOS line to develop our 3D-SiPM. This dissertation focuses on SPAD design, characterization and optimization made in the TDSI-CMOSP8G technology.

O nitrogênio e o potássio são essenciais para o desenvolvimento das plantas, são os nutrientes extraídos em altas quantidades e sua disponibilidade pode alterar as características produtivas e nutricionais das plantas. Assim, objetivou-se estudar: a) as características morfogênicas e a produção de massa seca da parte aérea e das raízes da Brachiaria brizantha cv. Marandu e b) a concentração de nitrogênio, potássio, nitrato e amônio nas lâminas de folhas recém-expandidas e nas raízes, bem como o valor SPAD, a atividade da enzima redutase do nitrato, a distribuição percentual do nitrato e amônio nas partes da planta forrageira e a distribuição percentual de nitrato e amônio entre parte aérea e raízes na Brachiaria brizantha cv. Marandu, submetida a combinações de doses de nitrogênio e potássio. O experimento foi realizado em casa de vegetação em solução nutritiva empregando-se sílica como substrato no período de dezembro de 2007 a fevereiro de 2008. Utilizou-se o esquema fatorial 52 fracionado, com 13 combinações de nitrogênio e potássio, as quais foram distribuídas segundo o delineamento de blocos ao acaso, com quatro repetições. Foram realizados dois cortes nas plantas. A interação doses de nitrogênio x doses de potássio foi significativa para número de perfilhos e de folhas, área foliar, massa seca da parte aérea e de raízes, comprimento e superfície total radicular e comprimento e superfície específica das raízes. A produção de massa seca da parte aérea teve forte correlação positiva com os parâmetros produtivos. As doses de nitrogênio se mostraram moduladoras do desenvolvimento do sistema radicular, o comprimento e superfície específicos diminuíram com emprego de altas doses de nitrogênio e potássio. A interação doses de nitrogênio x doses de potássio foi significativa para as concentrações de nitrogênio, potássio, nitrato e amônio em lâminas de folhas recém-expandidas e nas raízes. A atividade da enzima redutase do nitrato sofreu incremento com aumento das doses de nitrogênio e de potássio, em si. A distribuição percentual de nitrato e amônio ocorreu na ordem: colmos mais bainhas > lâminas de folhas recém-expandidas > folhas em expansão > lâminas de folhas maduras, evidenciando os colmos mais bainhas como parte da planta de acúmulo de nitrato e amônio e de mais baixa atividade da enzima redutase do nitrato. As doses de nitrogênio mostraram-se grande influenciadoras do valor SPAD, que aumentou com incremento de nitrogênio na solução nutritiva. O nitrogênio e o potássio alteram as características morfogênicas do capim-Marandu sendo determinantes para produção de massa seca da parte aérea e das raízes e que o desenvolvimento do sistema radicular é dependente de adequada nutrição, principalmente com nitrogênio. O nitrogênio e o potássio influenciaram o estado nutricional do capim-Marandu sendo determinantes para incremento do valor SPAD, atividade da enzima redutase do nitrato e concentração de nitrogênio, potássio, nitrato e amônio na parte aérea e nas raízes dessa gramínea. / Nitrogen and potassium are essentials for plant development, are extracted by plants in high amounts and their availabilities may change the morphogenetic, productive and nutritional characteristics of plants. The objectives of this research were: a) to assess fertilization with nitrogen and potassium rates on morphogenetic and shoot and root dry matter production of Brachiaria brizantha cv. Marandu; b) to evaluate the nitrogen, potassium, nitrate and ammonium concentration in the recently expanded leaf laminae and in the roots, SPAD values, and nitrate reductase activity, and ammonium and nitrate distribution in parts of Marandu palisadegrass in response to nitrogen and potassium rates combinations in nutrient solution. A greenhouse experiment was carried out, using ground quartz as a substrate, from December/2007 to February/2008. The experimental design used was fractionated 52 factorial, with 13 combinations of nitrogen and potassium rates, set in randomized block design with four replications. Two harvests were done in the plants. The nitrogen rates x potassium rates interaction was significant for the number of tiller, number of leaves, leaf area, above-ground, roots dry matter, total and specific root length, and total and specific root surface. Forage grass above-ground yield was positively correlated with number of tillers, number of leaves and leaf area. Nitrogen rates modulated the root system development, and the root specific length and surface decreased when high rates of both nitrogen and potassium were applied. Nitrogen rates x potassium rates interaction was significant for nitrogen, potassium, nitrate and ammonium concentrations in the recently expanded leaf laminae and in the roots. Nitrate reductase activity was increased with increasing the rates of both nitrogen and potassium. Nitrate and ammonium content in plant shoot were distributed following the order: culms+sheaths > recently expanded leaf laminae > emergent leaves > mature leaf laminae, showing culms+sheaths as a plant part of nitrate and ammonium a low nitrate reductase activity. Nitrogen rates highly influenced SPAD values, which increased with nitrogen rates in the nutrient solution. Nitrogen and potassium may affect the morphogenetic characteristics of Marandu palisadegrass, which were determinant for above-ground and root dry matter. The development of the root system depended on adequate plant nutrition, mainly in nitrogen. Nitrogen and potassium influenced the mineral nutrition status of Marandu palisadegrass and they increased the SPAD values, nitrate reductase activity, and nitrogen, potassium, nitrate and ammonium concentrations in shoots and roots of grass.

Espécies vegetais cultivadas em ambientes com altas concentrações de cromo (Cr) apresentam danos estruturais e baixa produção de massa seca da parte aérea e das raízes. O enxofre (S) é capaz de aliviar a toxidez provocada por metais pesados por ativar enzimas antioxidantes e produzir compostos capazes de imobilizar os metais. Objetivou-se avaliar as modificações estruturais, nutricionais e bioquímicas ocorridas no capim tanzânia crescendo com três doses de S (0,1; 1,9 e 3,7 mmol L-1) combinadas com quatro doses de Cr (0,0; 0,5; 1,0 e 2,0 mmol L-1), em solução nutritiva. O experimento foi conduzido em casa de vegetação em período de verão, utilizando um fatorial no delineamento de blocos completos casualizados, com seis repetições. O primeiro corte do capim foi realizado 33 dias após o transplantio das mudas para os vasos e o segundo corte 25 dias após o primeiro. O S amenizou o efeito tóxico do Cr aumentando a emissão de folhas e perfilhos e promovendo maior produção de massa seca de parte aérea. O índice relativo de clorofila (valor SPAD) nas lâminas recém-expandidas relacionou-se com os sintomas de clorose e necrose observados no primeiro crescimento. A dose residual de Cr estimulou a atividade fotossintética das folhas que apresentaram tonalidade verde escuro. Houve aumento na concentração e no acúmulo de S e de Cr na parte aérea do capim tanzânia com o fornecimento das doses combinadas do nutriente com o metal. A deficiência de S fez aumentar as concentrações de fósforo e de cobre na parte aérea. O capim absorveu maiores quantidades de micronutrientes para controlar o estresse provocado pela toxidez do Cr. A taxa fotossintética do capim tanzânia foi menor nas plantas contaminadas com Cr o que causou maior atividade das enzimas catalase, ascorbato peroxidase, guaiacol peroxidase e glutationa redutase na parte aérea. Aumento na concentração do peróxido de hidrogênio foi observado pela maior atividade da enzima superóxido dismutase quando foi utilizada dose de S de 0,1 mmol L-1 combinada com as doses de Cr, principalmente nas demais partes - folhas mais maduras, colmos e bainhas. O S amenizou o efeito tóxico do Cr no capim tanzânia aumentando as emissões de folhas e de perfilhos, a produção de biomassa, a absorção de micronutrientes e a atividade da enzima guaiacol peroxidase. O estresse por deficiência de S ou excesso de Cr resultou em aumento na síntese de prolina. O capim tanzânia possui habilidade em sobreviver sob contaminação com Cr quando adequadamente nutrido com S. / Plant species grown in environments with high concentrations of chromium (Cr) exhibit structural damage and lower dry mass production of shoot and root. Sulfur (S) is able to aleviatte the toxicity caused by heavy metals by activating antioxidant enzymes and producing compounds capable of immobilizing heavy metals. The aim was to evaluate structural, nutritional and biochemical changes occurring in tanzania guinea grass growing with three doses of S (0.1, 1.9 and 3.7 mmol L-1) combined with four doses of Cr (0.0, 0.5, 1.0 and 2.0 mmol L-1) in nutrient solution. The experiment was conducted in a greenhouse during the Summer season, by using a factorial in a randomized complete block design with six replications. The first harvest of the grass was done at 33 days after the transplanting of seedlings to the pots and second harvest at 25 days after the first one. S decreased the toxic effect of Cr increasing the emission of leaves and tillers and promoting higher production of shoots dry mass. Relative chlorophyll index (SPAD value) in newly expanded lamina leaves was associated to symptoms of chlorosis and necrosis observed in the plants during the first growth. Residual Cr stimulated photosynthetic activity of leaves, which presented dark green color. There was an increase in the concentrations and accumulations of S and Cr in shoots of tanzania guinea grass with the supply of combined rates of nutrient and metal. S deficiency increased the concentrations of phosphorus and copper in shoots. The grass uptook larger amounts of micronutrients to control stress caused by toxicity of Cr. The photosynthetic rate in tanzania guinea grass was low in contaminated plants, which resulted in high activity of the enzymes catalase, ascorbate peroxidase, guaiacol peroxidase and glutathione reductase in the shoots. The increase in hydrogen peroxide concentration was observed due to the high activity of the superoxide dismutase enzyme when the S rate was 0.1 mmol L-1 in combination with Cr rates, mainly in the more mature leaves, culms and sheaths. S alleviated the toxic effect of Cr in tanzania guinea grass by increasing leaf emission, tillering, biomass production, micronutrient uptake and guaiacol peroxidase enzyme activity. Stress caused for sulfur deficiency or Cr excess result in high synthesis of proline. Tanzania guinea grass has ability to survive under Cr contamination when adequately supplied with S.

O nitrogênio e o potássio são essenciais para o desenvolvimento das plantas, são os nutrientes extraídos em altas quantidades e sua disponibilidade pode alterar as características produtivas e nutricionais das plantas. Assim, objetivou-se estudar: a) as características morfogênicas e a produção de massa seca da parte aérea e das raízes da Brachiaria brizantha cv. Marandu e b) a concentração de nitrogênio, potássio, nitrato e amônio nas lâminas de folhas recém-expandidas e nas raízes, bem como o valor SPAD, a atividade da enzima redutase do nitrato, a distribuição percentual do nitrato e amônio nas partes da planta forrageira e a distribuição percentual de nitrato e amônio entre parte aérea e raízes na Brachiaria brizantha cv. Marandu, submetida a combinações de doses de nitrogênio e potássio. O experimento foi realizado em casa de vegetação em solução nutritiva empregando-se sílica como substrato no período de dezembro de 2007 a fevereiro de 2008. Utilizou-se o esquema fatorial 52 fracionado, com 13 combinações de nitrogênio e potássio, as quais foram distribuídas segundo o delineamento de blocos ao acaso, com quatro repetições. Foram realizados dois cortes nas plantas. A interação doses de nitrogênio x doses de potássio foi significativa para número de perfilhos e de folhas, área foliar, massa seca da parte aérea e de raízes, comprimento e superfície total radicular e comprimento e superfície específica das raízes. A produção de massa seca da parte aérea teve forte correlação positiva com os parâmetros produtivos. As doses de nitrogênio se mostraram moduladoras do desenvolvimento do sistema radicular, o comprimento e superfície específicos diminuíram com emprego de altas doses de nitrogênio e potássio. A interação doses de nitrogênio x doses de potássio foi significativa para as concentrações de nitrogênio, potássio, nitrato e amônio em lâminas de folhas recém-expandidas e nas raízes. A atividade da enzima redutase do nitrato sofreu incremento com aumento das doses de nitrogênio e de potássio, em si. A distribuição percentual de nitrato e amônio ocorreu na ordem: colmos mais bainhas > lâminas de folhas recém-expandidas > folhas em expansão > lâminas de folhas maduras, evidenciando os colmos mais bainhas como parte da planta de acúmulo de nitrato e amônio e de mais baixa atividade da enzima redutase do nitrato. As doses de nitrogênio mostraram-se grande influenciadoras do valor SPAD, que aumentou com incremento de nitrogênio na solução nutritiva. O nitrogênio e o potássio alteram as características morfogênicas do capim-Marandu sendo determinantes para produção de massa seca da parte aérea e das raízes e que o desenvolvimento do sistema radicular é dependente de adequada nutrição, principalmente com nitrogênio. O nitrogênio e o potássio influenciaram o estado nutricional do capim-Marandu sendo determinantes para incremento do valor SPAD, atividade da enzima redutase do nitrato e concentração de nitrogênio, potássio, nitrato e amônio na parte aérea e nas raízes dessa gramínea. / Nitrogen and potassium are essentials for plant development, are extracted by plants in high amounts and their availabilities may change the morphogenetic, productive and nutritional characteristics of plants. The objectives of this research were: a) to assess fertilization with nitrogen and potassium rates on morphogenetic and shoot and root dry matter production of Brachiaria brizantha cv. Marandu; b) to evaluate the nitrogen, potassium, nitrate and ammonium concentration in the recently expanded leaf laminae and in the roots, SPAD values, and nitrate reductase activity, and ammonium and nitrate distribution in parts of Marandu palisadegrass in response to nitrogen and potassium rates combinations in nutrient solution. A greenhouse experiment was carried out, using ground quartz as a substrate, from December/2007 to February/2008. The experimental design used was fractionated 52 factorial, with 13 combinations of nitrogen and potassium rates, set in randomized block design with four replications. Two harvests were done in the plants. The nitrogen rates x potassium rates interaction was significant for the number of tiller, number of leaves, leaf area, above-ground, roots dry matter, total and specific root length, and total and specific root surface. Forage grass above-ground yield was positively correlated with number of tillers, number of leaves and leaf area. Nitrogen rates modulated the root system development, and the root specific length and surface decreased when high rates of both nitrogen and potassium were applied. Nitrogen rates x potassium rates interaction was significant for nitrogen, potassium, nitrate and ammonium concentrations in the recently expanded leaf laminae and in the roots. Nitrate reductase activity was increased with increasing the rates of both nitrogen and potassium. Nitrate and ammonium content in plant shoot were distributed following the order: culms+sheaths > recently expanded leaf laminae > emergent leaves > mature leaf laminae, showing culms+sheaths as a plant part of nitrate and ammonium a low nitrate reductase activity. Nitrogen rates highly influenced SPAD values, which increased with nitrogen rates in the nutrient solution. Nitrogen and potassium may affect the morphogenetic characteristics of Marandu palisadegrass, which were determinant for above-ground and root dry matter. The development of the root system depended on adequate plant nutrition, mainly in nitrogen. Nitrogen and potassium influenced the mineral nutrition status of Marandu palisadegrass and they increased the SPAD values, nitrate reductase activity, and nitrogen, potassium, nitrate and ammonium concentrations in shoots and roots of grass.

La tomographie d'émission par positrons (TEP) est un outil précieux en recherche préclinique et pour le diagnostic médical. Cette technique permet d'obtenir une image quantitative de fonctions métaboliques spécifiques par la détection de photons d'annihilation. La détection des ces photons se fait à l'aide de deux composantes. D'abord, un scintillateur convertit l'énergie du photon 511 keV en photons du spectre visible. Ensuite, un photodétecteur convertit l'énergie lumineuse en signal électrique. Récemment, les photodiodes avalanche monophotoniques (PAMP) disposées en matrice suscitent beaucoup d'intérêt pour la TEP. Ces matrices forment des détecteurs sensibles, robustes, compacts et avec une résolution en temps hors pair. Ces qualités en font un photodétecteur prometteur pour la TEP, mais il faut optimiser les paramètres de la matrice et de l'électronique de lecture afin d'atteindre les performances optimales pour la TEP. L'optimisation de la matrice devient rapidement une opération difficile, car les différents paramètres interagissent de manière complexe avec les processus d'avalanche et de génération de bruit. Enfin, l'électronique de lecture pour les matrices de PAMP demeure encore rudimentaire et il serait profitable d'analyser différentes stratégies de lecture. Pour répondre à cette question, la solution la plus économique est d'utiliser un simulateur pour converger vers la configuration donnant les meilleures performances. Les travaux de ce mémoire présentent le développement d'un tel simulateur. Celui-ci modélise le comportement d'une matrice de PAMP en se basant sur les équations de physique des semiconducteurs et des modèles probabilistes. Il inclut les trois principales sources de bruit, soit le bruit thermique, les déclenchements intempestifs corrélés et la diaphonie optique. Le simulateur permet aussi de tester et de comparer de nouvelles approches pour l'électronique de lecture plus adaptées à ce type de détecteur. Au final, le simulateur vise à quantifier l'impact des paramètres du photodétecteur sur la résolution en énergie et la résolution en temps et ainsi optimiser les performances de la matrice de PAMP. Par exemple, l'augmentation du ratio de surface active améliore les performances, mais seulement jusqu'à un certain point. D'autres phénomènes liés à la surface active, comme le bruit thermique, provoquent une dégradation du résultat. Le simulateur nous permet de trouver un compromis entre ces deux extrêmes. Les simulations avec les paramètres initiaux démontrent une efficacité de détection de 16,7 %, une résolution en énergie de 14,2 % LMH et une résolution en temps de 0.478 ns LMH. Enfin, le simulateur proposé, bien qu'il vise une application en TEP, peut être adapté pour d'autres applications en modifiant la source de photons et en adaptant les objectifs de performances.

Le noyau d'une cellule est hétérogène par sa structure et son activité et beaucoup de ses composants interagissent de façon dynamique. Lors de l'étude de processus cellulaires comme la réponse au stress thermique, des expériences classiques de spectroscopie de corrélation de fluorescence (FCS), qui sont habituellement limitées à un seul volume d'observation, n'apportent que des résultats partiels à cause des informations spatiales manquantes. Ce mémoire de thèse présente une nouvelle technique de FCS multi-confocale (mFCS) qui permet des mesures FCS simultanées à différents endroits d'une cellule. La technique est basée sur l'emploi d'un modulateur spatial de lumière pour la création de plusieurs volumes d'observations distincts et d'une caméra ''electron-multiplying'' CCD (EMCCD) pour la détection en parallèle. La résolution spatiale ainsi que la sensibilité du système mFCS sont proches de celles d'un système FCS classique et en utilisant un mode d'acquisition particulier une résolution temporelle de $14mu s$ a pu être atteinte. La technique mFCS est appliquée à l'étude de la réponse cellulaire au stress thermique en observant le facteur de transcription heat shock factor 1 (HSF1), qui est un régulateur clé de la réponse au stress thermique. Des mesures mFCS dans des cellules vivantes révèlent des changements dans la dynamique de HSF1 pendant le choc thermique. Ces changements concernent l'affinité ainsi que l'homogénéité spatiale des interactions avec l'ADN. En outre, nous avons également évalué les performances d'une caméra CMOS-SPAD et testé le dispositif en tant que capteur alternatif pour la mFCS en cellules vivantes.

Espécies vegetais cultivadas em ambientes com altas concentrações de cromo (Cr) apresentam danos estruturais e baixa produção de massa seca da parte aérea e das raízes. O enxofre (S) é capaz de aliviar a toxidez provocada por metais pesados por ativar enzimas antioxidantes e produzir compostos capazes de imobilizar os metais. Objetivou-se avaliar as modificações estruturais, nutricionais e bioquímicas ocorridas no capim tanzânia crescendo com três doses de S (0,1; 1,9 e 3,7 mmol L-1) combinadas com quatro doses de Cr (0,0; 0,5; 1,0 e 2,0 mmol L-1), em solução nutritiva. O experimento foi conduzido em casa de vegetação em período de verão, utilizando um fatorial no delineamento de blocos completos casualizados, com seis repetições. O primeiro corte do capim foi realizado 33 dias após o transplantio das mudas para os vasos e o segundo corte 25 dias após o primeiro. O S amenizou o efeito tóxico do Cr aumentando a emissão de folhas e perfilhos e promovendo maior produção de massa seca de parte aérea. O índice relativo de clorofila (valor SPAD) nas lâminas recém-expandidas relacionou-se com os sintomas de clorose e necrose observados no primeiro crescimento. A dose residual de Cr estimulou a atividade fotossintética das folhas que apresentaram tonalidade verde escuro. Houve aumento na concentração e no acúmulo de S e de Cr na parte aérea do capim tanzânia com o fornecimento das doses combinadas do nutriente com o metal. A deficiência de S fez aumentar as concentrações de fósforo e de cobre na parte aérea. O capim absorveu maiores quantidades de micronutrientes para controlar o estresse provocado pela toxidez do Cr. A taxa fotossintética do capim tanzânia foi menor nas plantas contaminadas com Cr o que causou maior atividade das enzimas catalase, ascorbato peroxidase, guaiacol peroxidase e glutationa redutase na parte aérea. Aumento na concentração do peróxido de hidrogênio foi observado pela maior atividade da enzima superóxido dismutase quando foi utilizada dose de S de 0,1 mmol L-1 combinada com as doses de Cr, principalmente nas demais partes - folhas mais maduras, colmos e bainhas. O S amenizou o efeito tóxico do Cr no capim tanzânia aumentando as emissões de folhas e de perfilhos, a produção de biomassa, a absorção de micronutrientes e a atividade da enzima guaiacol peroxidase. O estresse por deficiência de S ou excesso de Cr resultou em aumento na síntese de prolina. O capim tanzânia possui habilidade em sobreviver sob contaminação com Cr quando adequadamente nutrido com S. / Plant species grown in environments with high concentrations of chromium (Cr) exhibit structural damage and lower dry mass production of shoot and root. Sulfur (S) is able to aleviatte the toxicity caused by heavy metals by activating antioxidant enzymes and producing compounds capable of immobilizing heavy metals. The aim was to evaluate structural, nutritional and biochemical changes occurring in tanzania guinea grass growing with three doses of S (0.1, 1.9 and 3.7 mmol L-1) combined with four doses of Cr (0.0, 0.5, 1.0 and 2.0 mmol L-1) in nutrient solution. The experiment was conducted in a greenhouse during the Summer season, by using a factorial in a randomized complete block design with six replications. The first harvest of the grass was done at 33 days after the transplanting of seedlings to the pots and second harvest at 25 days after the first one. S decreased the toxic effect of Cr increasing the emission of leaves and tillers and promoting higher production of shoots dry mass. Relative chlorophyll index (SPAD value) in newly expanded lamina leaves was associated to symptoms of chlorosis and necrosis observed in the plants during the first growth. Residual Cr stimulated photosynthetic activity of leaves, which presented dark green color. There was an increase in the concentrations and accumulations of S and Cr in shoots of tanzania guinea grass with the supply of combined rates of nutrient and metal. S deficiency increased the concentrations of phosphorus and copper in shoots. The grass uptook larger amounts of micronutrients to control stress caused by toxicity of Cr. The photosynthetic rate in tanzania guinea grass was low in contaminated plants, which resulted in high activity of the enzymes catalase, ascorbate peroxidase, guaiacol peroxidase and glutathione reductase in the shoots. The increase in hydrogen peroxide concentration was observed due to the high activity of the superoxide dismutase enzyme when the S rate was 0.1 mmol L-1 in combination with Cr rates, mainly in the more mature leaves, culms and sheaths. S alleviated the toxic effect of Cr in tanzania guinea grass by increasing leaf emission, tillering, biomass production, micronutrient uptake and guaiacol peroxidase enzyme activity. Stress caused for sulfur deficiency or Cr excess result in high synthesis of proline. Tanzania guinea grass has ability to survive under Cr contamination when adequately supplied with S.

The master’s thesis deals about portfolio securities optimalization on Prague stock exchange. After the theoretical part follows global fundamental analysis with the guess of market trends. Next part describes fundemantal analysis on the association´s level. On the basis of fundamental analysis results was created optimized securities portfolio.

No description available.

Vision has always been one of the most important cognitive tools of human beings. In this regard, the development of image sensors opens up the potential to view objects that our eyes cannot see. One of the most promising capability in some image sensors is their single-photon sensitivity that provides information at the ultimate fundamental limit of light. Time-resolved single-photon avalanche diode (SPAD) image sensors bring a new dimension as they measure the arrival time of incident photons with a precision in the order of hundred picoseconds. In addition to this characteristic, they can be fabricated in complementary metal-oxide-semiconductor (CMOS) technology enabling the integration of complex signal processing blocks at the pixel level. These unique features made CMOS SPAD sensors a prime candidate for a broad spectrum of applications. This thesis is dedicated to the optimization and characterization of quantum imagers based on the SPADs as part of the E.U. funded SUPERTWIN project to surpass the fundamental diffraction limit known as the Rayleigh limit by exploiting the spatio-temporal correlation of entangled photons. The first characterized sensor is a 32×32-pixel SPAD array, named “SuperEllen”, with in-pixel time-to-digital converters (TDC) that measure the spatial cross-correlation functions of a flux of entangled photons. Each pixel features 19.48% fill-factor (FF) in 44.64-μm pitch fabricated in a 150-nm CMOS standard technology. The sensor is fully characterized in several electro-optical experiments, in order to be used in quantum imaging measurements. Moreover, the chip is calibrated in terms of coincidence detection achieving the minimal coincidence window determined by the SPAD jitter. The second developed sensor in the context of SUPERTWIN project is a 224×272-pixel SPAD-based array called “SuperAlice”, a multi-functional image sensor fabricated in a 110-nm CMOS image sensor technology. SuperAlice can operate in multiple modes (time-resolving or photon counting or binary imaging mode). Thanks to the digital intrinsic nature of SPAD imagers, they have an inherent capability to achieve a high frame rate. However, running at high frame rate means high I/O power consumption and thus inefficient handling of the generated data, as SPAD arrays are employed for low light applications in which data are very sparse over time and space. Here, we present three zero-suppression mechanisms to increase the frame rate without adversely affecting power consumption. A row-skipping mechanism that is implemented in both SuperEllen and SuperAlice detects the absence of SPAD activity in a row to increase the duty cycle. A current-based mechanism implemented in SuperEllen ignores reading out a full frame when the number of triggered pixels is less than a user-defined value. A different zero-suppression technique is developed in the SuperAlice chip that is based on jumping through the non-zero pixels within one row. The acquisition of TDC-based SPAD imagers can be speeded up further by storing and processing events inside the chip without the need to read out all data. An on-chip histogramming architecture based on analog counters is developed in a 150-nm CMOS standard technology. The test structure is a 16-bin histogram with 9 bit depth for each bin. SPAD technology demonstrates its capability in other applications such as automotive that demands high dynamic range (HDR) imaging. We proposed two methods based on processing photon arrival times to create HDR images. The proposed methods are validated experimentally with SuperEllen obtaining >130 dB dynamic range within 30 ms of integration time and can be further extended by using a timestamping mechanism with a higher resolution.