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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Análise dos fluxos auxínicos que levam à senescência da raiz embrionária e a formação das raízes da coroa na espécie modelo Setaria viridis / Analysis of auxin fluxes carring to senescence of the embryonic root and the formation of crown roots in the species Setaria viridis

Pedroso, Aline 11 January 2019 (has links)
Setaria viridis tem sido utilizada como organismo modelo para gramíneas com metabolismo C4, buscando elucidar processos biológicos de plantas. A importância das monocotiledôneas com o metabolismo de C4 deve-se ao melhor balanço fotossintético quando comparado às plantas com metabolismo C3 em condições climáticas com altas temperaturas, como as que prevalecem no Brasil. Setaria viridis representa um sistema modelo de grande importância para a agricultura brasileira, uma vez que tanto a produção brasileira de biocombustíveis como de alimentos está fortemente relacionada aos organismos C4. Os hormônios vegetais são cruciais no estabelecimento de órgãos complexos desde o zigoto até o desenvolvimento da planta adulta. A auxina em particular, desempenha um papel fundamental na formação de um complexo sistema radicular nas plantas. Sabe-se que o transporte polar desse hormônio concentra a auxina em determinados tecidos, desempenhando um papel essencial na expressão diferencial de genes que modulam o desenvolvimento dos vários órgãos da planta. Monocotiledôneas e em particular Poaeceaes exibem um complexo sistema radicular que parece ser chave para o seu vasto potencial adaptativo, mas pouco se sabe sobre os fatores que envolvem as respostas sensoriais e de desenvolvimento que guiam a escolha de quais tipos de raiz as plantas elegem. O objetivo deste estudo foi explorar as vias hormonais e abióticas que influenciam a arquitetura das raízes / Setaria viridis has been used as a model organism for grasses with C4 metabolism, seeking to elucidate plant biological processes. The importance of monocotyledons with C4 metabolism is due to better photosynthetic balance when compared to plants with C3 metabolism in climatic conditions with high temperatures, such as those that prevail in Brazil. Setaria viridis represents a model system of great importance for Brazilian agriculture since both the Brazilian production of biofuels and food is strongly related to C4 organisms. Plant hormones are crucial in the establishment of complex organs from zygote to the adult plant development. Auxin in particular, plays a key role in the formation of a complex radicular system in plants. The polar transport of this hormone is known to concentrate auxin in particular tissues, playing an essential roll in the differential expression of genes that will modulate the development of the various plant organs. Monocots and in particular Poaeceae display a complex radicular system that seems to be key for it vast adaptive potential, but little is known about the factors involving the sensing and developmental responses that guide the choice of which root types to elect. The aim of this study was to explore the hormonal and abiotic cues that influence the root architecture
92

Análise dos fluxos auxínicos que levam à senescência da raiz embrionária e a formação das raízes da coroa na espécie modelo Setaria viridis / Analysis of auxin fluxes carring to senescence of the embryonic root and the formation of crown roots in the species Setaria viridis

Aline Pedroso 11 January 2019 (has links)
Setaria viridis tem sido utilizada como organismo modelo para gramíneas com metabolismo C4, buscando elucidar processos biológicos de plantas. A importância das monocotiledôneas com o metabolismo de C4 deve-se ao melhor balanço fotossintético quando comparado às plantas com metabolismo C3 em condições climáticas com altas temperaturas, como as que prevalecem no Brasil. Setaria viridis representa um sistema modelo de grande importância para a agricultura brasileira, uma vez que tanto a produção brasileira de biocombustíveis como de alimentos está fortemente relacionada aos organismos C4. Os hormônios vegetais são cruciais no estabelecimento de órgãos complexos desde o zigoto até o desenvolvimento da planta adulta. A auxina em particular, desempenha um papel fundamental na formação de um complexo sistema radicular nas plantas. Sabe-se que o transporte polar desse hormônio concentra a auxina em determinados tecidos, desempenhando um papel essencial na expressão diferencial de genes que modulam o desenvolvimento dos vários órgãos da planta. Monocotiledôneas e em particular Poaeceaes exibem um complexo sistema radicular que parece ser chave para o seu vasto potencial adaptativo, mas pouco se sabe sobre os fatores que envolvem as respostas sensoriais e de desenvolvimento que guiam a escolha de quais tipos de raiz as plantas elegem. O objetivo deste estudo foi explorar as vias hormonais e abióticas que influenciam a arquitetura das raízes / Setaria viridis has been used as a model organism for grasses with C4 metabolism, seeking to elucidate plant biological processes. The importance of monocotyledons with C4 metabolism is due to better photosynthetic balance when compared to plants with C3 metabolism in climatic conditions with high temperatures, such as those that prevail in Brazil. Setaria viridis represents a model system of great importance for Brazilian agriculture since both the Brazilian production of biofuels and food is strongly related to C4 organisms. Plant hormones are crucial in the establishment of complex organs from zygote to the adult plant development. Auxin in particular, plays a key role in the formation of a complex radicular system in plants. The polar transport of this hormone is known to concentrate auxin in particular tissues, playing an essential roll in the differential expression of genes that will modulate the development of the various plant organs. Monocots and in particular Poaeceae display a complex radicular system that seems to be key for it vast adaptive potential, but little is known about the factors involving the sensing and developmental responses that guide the choice of which root types to elect. The aim of this study was to explore the hormonal and abiotic cues that influence the root architecture
93

Estudo da assimetria da informação e seus impactos no custo de capital das empresas brasileiras negociadas em bolsa / Study of asymmetry information and its impacts on capital cost of Brazilian companies traded in stock exchange

Calhau, Fabio Ricardo dos Santos 20 December 2012 (has links)
O objetivo principal deste trabalho é analisar o efeito da assimetria da informação no custo de capital próprio das empresas negociadas em bolsa de valores no Brasil. O tema está em constante debate sobre a existência dessa relação e até mesmo sobre sua relação com o custo de capital ser favorável ou não. A assimetria da informação foi estimada através da Probability of informed trading (PIN), mensurando de forma direta a existência de negociações com informação privilegiada para a confrontação com custo de capital das empresas brasileiras. O resultado encontrado não apresentou relação estatisticamente significante a 5% entre a PIN e o custo de capital, de forma que não foi possível verificar a relação entre assimetria da informação e o custo de capital. Adicionalmente, o coeficiente encontrado para a PIN no modelo adotado indica uma possível correlação negativa da variável estudada e o custo de capital, deste modo o estudo corrobora com a conclusão de Lambert et al. (2012), segundo a qual, em mercados líquidos, a assimetria da informação não exerce papel relevante e sim a quantidade e a qualidade da informação disponível, não importando a forma de entrada da informação no mercado. / The main objective of this thesis is to analyze the effect of information asymmetry on the cost of equity of companies traded in stock exchanges in Brazil. It is constantly debated whether this relationship exists and also whether information asymmetry\'s effect on the cost of equity is favorable or not. Information asymmetry has been estimated using the PIN (Probability of Informed Trading), directly measuring the existence of insider trading for confrontation with the cost of equity of Brazilian companies. The result obtained did not show a statistically significant relationship at the 5% level between the PIN and the cost of equity; therefore, it was not possible to ascertain the relationship between information asymmetry and cost of equity. Additionally, the coefficient found for the PIN on the selected model indicates a possible negative correlation between the studied variable and the cost of equity, which indicates that the study corroborates the conclusion of Lambert et al. (2012), according to which information asymmetry does not exert a significant role in liquid markets but rather this role is exerted by the quantity and quality of available information, regardless of how information reaches the market.
94

Einfluss von Gibberellin auf den Gravitropismus der Wurzel durch Regulation der PIN-Stabilität / Gibberellin modulates root gravitropism via regulation of PIN stability

Löfke, Christian 29 April 2011 (has links)
No description available.
95

Estudo da assimetria da informação e seus impactos no custo de capital das empresas brasileiras negociadas em bolsa / Study of asymmetry information and its impacts on capital cost of Brazilian companies traded in stock exchange

Fabio Ricardo dos Santos Calhau 20 December 2012 (has links)
O objetivo principal deste trabalho é analisar o efeito da assimetria da informação no custo de capital próprio das empresas negociadas em bolsa de valores no Brasil. O tema está em constante debate sobre a existência dessa relação e até mesmo sobre sua relação com o custo de capital ser favorável ou não. A assimetria da informação foi estimada através da Probability of informed trading (PIN), mensurando de forma direta a existência de negociações com informação privilegiada para a confrontação com custo de capital das empresas brasileiras. O resultado encontrado não apresentou relação estatisticamente significante a 5% entre a PIN e o custo de capital, de forma que não foi possível verificar a relação entre assimetria da informação e o custo de capital. Adicionalmente, o coeficiente encontrado para a PIN no modelo adotado indica uma possível correlação negativa da variável estudada e o custo de capital, deste modo o estudo corrobora com a conclusão de Lambert et al. (2012), segundo a qual, em mercados líquidos, a assimetria da informação não exerce papel relevante e sim a quantidade e a qualidade da informação disponível, não importando a forma de entrada da informação no mercado. / The main objective of this thesis is to analyze the effect of information asymmetry on the cost of equity of companies traded in stock exchanges in Brazil. It is constantly debated whether this relationship exists and also whether information asymmetry\'s effect on the cost of equity is favorable or not. Information asymmetry has been estimated using the PIN (Probability of Informed Trading), directly measuring the existence of insider trading for confrontation with the cost of equity of Brazilian companies. The result obtained did not show a statistically significant relationship at the 5% level between the PIN and the cost of equity; therefore, it was not possible to ascertain the relationship between information asymmetry and cost of equity. Additionally, the coefficient found for the PIN on the selected model indicates a possible negative correlation between the studied variable and the cost of equity, which indicates that the study corroborates the conclusion of Lambert et al. (2012), according to which information asymmetry does not exert a significant role in liquid markets but rather this role is exerted by the quantity and quality of available information, regardless of how information reaches the market.
96

Estudo da aplicação do processo Pin-in-Paste na montagem de placas de circuito impresso usando pasta de solda lead-free (SAC). / Study of the Pin-in-Paste process in the printed circuit board assembly using lead free solder paste (SAC).

Ricardo Barbosa de Lima 31 October 2011 (has links)
Neste trabalho foram estudadas as etapas de processo envolvidas na tecnologia Pin-in-Paste (PIP) de soldagem por refusão de componentes convencionais (THCs - Through Hole Components ou Componentes de Furo Passante) em placas de circuito impresso (PCIs), utilizando pasta de solda sem chumbo (lead-free) com liga SAC (Sn-Ag-Cu) de forma a atender as novas exigências ambientais para a montagem eletrônica. Inicialmente foi feito o projeto da PCI de teste com três diferentes componentes THCs e três componentes SMD com encapsulamentos distintos, com o objetivo de reproduzir uma PCI comercial. Foram gerados dois diâmetros de furos diferentes para inserir os THCs, possibilitando o estudo da variação de preenchimento com solda no PTH. Foi proposta uma equação para o cálculo do volume de pasta de solda a ser impresso sobre os furos no processo de montagem. A partir desta equação foram calculadas as dimensões dos furos do estêncil para a PCI de teste. Os parâmetros de impressão foram otimizados em função da variação de pressão e da velocidade do rodo. Duas curvas de refusão foram utilizadas, uma convencional e outra otimizada para verificar a variação na geração de defeitos. A impressão de pasta de solda ficou superior ao projetado, o que resultou em todas as amostras terem solda acima do parâmetro mínimo de aceitabilidade de volume de 75% de preenchimento do PTH. Esta sobre impressão ocasionou defeitos em boa parte dos componentes, excesso de solda nos filetes e resíduos de fluxo na solda nos PTHs. Tais defeitos foram expressivos para todos os THCs, mostrando que o excesso de pasta impressa foi decisivo na geração de defeitos para todas as combinações das variáveis estudadas. Os SMDs tiveram solda aceitável, apresentando apenas alguns casos de excesso de fluxo ou pouca solda em alguns QFPs devido ao uso de ilhas com dimensões maiores que o exigido em norma. O processo de Pin In Paste se mostra viável como substituto da solda onda em linhas de montagem para placas com SMDs e THCs, mas estudos posteriores deverão ser realizados para a geração de um modelo confiável de projeto de PCIs e estêncil com solda lead-free para que tal processo seja utilizado em grande escala na indústria. / This study describes the process steps involved in Pin-in-Paste (PIP) reflow soldering technology in printed circuit boards (PCBs) using lead-free solder paste with SAC alloy (Sn-Ag-Cu) in order to attend new environmental requirements for the electronics assembly. Initially it was designed a PCB test with three different THCs (Through Hole Component) and three different SMD (Surface Mount Device) packages in order to reproduce a commercial board. It was generated two different diameters of holes to insert the THCs, aiming to study the solder fill variation in PTH. An equation was proposed for calculating the volume of solder paste to be printed over the holes in the assembly process. From this equation it was calculated the dimensions of the holes of the stencil. The printing parameters were optimized according to the variation of pressure and speed of the squeegee. Two reflow curves were used in the process, a conventional one and an optimized one to determine the variations in the generation of soldering defects. The printed solder paste volume was higher than projected, which resulted in solder excess, causing defects in most of the components, such as excess solder in the fillet and solder flux residues in PTHs. Such defects were significant for all THCs, showing that the excess paste that was printed caused critical defects for all combinations of variables. Regarding that all samples were above the reflow minimum acceptable volume of 75% coverage of PTH. The SMDs solders were acceptable, with only few cases of solder flux excess. The Pin in Paste process was observed as a good option to replace the wave soldering thermal process for mixed PCBs. Further studies should be conducted to generate a reliable model of PCB and stencil design.
97

Mechanismy ustavení a udržení polarity PIN přenašečů v Arabidopsis / Mechanisms of establishment and maintenance of PIN polarity in Arabidopsis

Glanc, Matouš January 2019 (has links)
Cell polarity is a key concept in plant biology. The subcellular localization of Pin- formed (PIN) auxin efflux carriers in the root of "#$%&'()*&* is remarkably asymmetrical, making PINs prominent markers to study cell polarity. In spite of its developmental importance and two decades of research, the molecular basis of PIN polarity remains largely unknown. In this thesis, I employed advanced transgenic and fluorescence microscopy approaches to gain insight into several aspects of PIN polarity regulation. I participated in establishing a novel genetically encoded inhibitor of endocytosis, an invaluable tool for the study of the importance of endocytosis for various cellular processes, including PIN polarity. I demonstrated that apical polarity of PIN2 needs to be re-established after cell division and that this process depends on endocytosis, '+!,(-( protein secretion and the action of WAG1 and related protein kinases, but not transcytosis, cell-cell signaling or intact cytoskeleton. Finally, I identified the previously unknown role of MAB4/MEL proteins in PIN polarity, which lies in the ability of MAB4/MELs to reduce PIN lateral diffusion and thus contribute to PIN polarity maintenance. My results, besides broadening current understanding of PIN polarity regulation, identify mechanisms that...
98

Développement d’un circuit de lecture pour un calorimètre électromagnétique ultra-granulaire / Design of a read-out chip for a high granularity electromagnetic calorimeter

Cizel, Jean-Baptiste 09 December 2016 (has links)
Le travail réalisé lors de cette thèse s’inscrit dans le projet de création d’un calorimètre électromagnétique pour le futur International Linear Collider (ILC) au sein de la collaboration CALICE. Le calorimètre est dit ultra-granulaire du fait du grand nombre de pixels de détection : environ 82 millions dans le calorimètre final complet. C’est ce nombre élevé de détecteurs à lire qui a conduit au développement de circuits intégrés dédiés à cette tâche, l’usage d’électronique classique n’étant pas possible dans ce cas du fait de contraintes dimensionnelles. Les travaux démarrent par l’étude de la puce SKIROC2, développée par le laboratoire Omega, qui est l’état de l’art de l’ASIC de lecture pour ce projet. Les performances sur carte de test et dans l’environnement du détecteur ont été mesurées, ce qui a permis de tirer certaines conclusions sur les forces et les faiblesses de SKIROC2. Après cette étude, le travail a été le développement d’un nouvel ASIC de lecture se basant sur SKIROC2. L’objectif étant de préserver les forces de SKIROC2 tout en tentant d’en corriger les faiblesses. Le nouvel ASIC a été conçu dans une technologie tout juste disponible au moment de la conception. Il a donc tout fallu redessiner en repartant de zéro. Il s’agit en cela de building blocks plus que d’un véritable ASIC de lecture. Trois structures de préamplificateurs de charge ont été testées, l’architecture générale et le fonctionnement d’un canal de lecture étant largement inspirés de SKIROC2. / This work takes place in the design project of the electromagnetic calorimeter for the future International Linear Collider (ILC) within the CALICE collaboration. The final calorimeter will be made of 82 million of PIN diodes; this is where the term “high granularity” comes from. The need for a read-out ASIC is a consequence of this high number of detectors, knowing that the dimensions of the electromagnetic calorimeter are a big constraint: the standard electronics is not an option. This work starts from an existing ASIC called SKIROC2. This state-of-the-art read-out chip has been designed by the Omega laboratory, a member of the CALICE collaboration. The performances on testboard and in the detector environment have been measured. It allowed to conclude on the advantages and drawbacks of using SKIROC2 in the calorimeter. After that the focus has been made on the design of a new read-out chip based on SKIROC2. The main goal was to preserve the good performances of SKIROC2 while trying to correct the encountered issues. This new ASIC has been developped in a newly released technology available during the design phase. Therefore the design has been started from scratch. The final chip is composed of building blocks rather than a ready-to-use read-out chip. Three charge preamplifier designs have been tested, the general architecture of a read-out channel being largely inspired by SKIROC2.
99

Mechanismy ustavení a udržení polarity PIN přenašečů v Arabidopsis / Mechanisms of establishment and maintenance of PIN polarity in Arabidopsis

Glanc, Matouš January 2019 (has links)
Cell polarity is a key concept in plant biology. The subcellular localization of Pin- formed (PIN) auxin efflux carriers in the root of "#$%&'()*&* is remarkably asymmetrical, making PINs prominent markers to study cell polarity. In spite of its developmental importance and two decades of research, the molecular basis of PIN polarity remains largely unknown. In this thesis, I employed advanced transgenic and fluorescence microscopy approaches to gain insight into several aspects of PIN polarity regulation. I participated in establishing a novel genetically encoded inhibitor of endocytosis, an invaluable tool for the study of the importance of endocytosis for various cellular processes, including PIN polarity. I demonstrated that apical polarity of PIN2 needs to be re-established after cell division and that this process depends on endocytosis, '+!,(-( protein secretion and the action of WAG1 and related protein kinases, but not transcytosis, cell-cell signaling or intact cytoskeleton. Finally, I identified the previously unknown role of MAB4/MEL proteins in PIN polarity, which lies in the ability of MAB4/MELs to reduce PIN lateral diffusion and thus contribute to PIN polarity maintenance. My results, besides broadening current understanding of PIN polarity regulation, identify mechanisms that...
100

Breakdown Characteristics in SiC and Improvement of PiN Diodes toward Ultrahigh-Voltage Applications / 超高耐圧応用を目指したSiCにおける絶縁破壊特性の基礎研究およびPiNダイオードの高性能化

Niwa, Hiroki 23 March 2016 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19722号 / 工博第4177号 / 新制||工||1644(附属図書館) / 32758 / 京都大学大学院工学研究科電子工学専攻 / (主査)教授 木本 恒暢, 教授 髙岡 義寛, 教授 山田 啓文 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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