RAID-6 is widely used to tolerate concurrent failures of any two disks to provide a higher level of reliability with the support of erasure codes. Among many implementations, one class of codes called Maximum Distance Separable (MDS) codes aims to offer data protection against disk failures with optimal storage efficiency. Typical MDS codes contain horizontal and vertical codes. However, because of the limitation of horizontal parity or diagonal/anti-diagonal parities used in MDS codes, existing RAID-6 systems suffer several important problems on performance and scalability, such as low write performance, unbalanced I/O, and high migration cost in the scaling process. To address these problems, in this dissertation, we design techniques for high performance and scalable RAID-6 systems. It includes high performance and load balancing erasure codes (H-Code and HDP Code), and Stripe-based Data Migration (SDM) scheme. We also propose a flexible MDS Scaling Framework (MDS-Frame), which can integrate H-Code, HDP Code and SDM scheme together. Detailed evaluation results are also given in this dissertation.

Nesse estudo, explorei aspectos da ecologia evolutiva da interação planta-polinizador, ao avaliar o fenótipo floral sob pressões seletivas geograficamente divergentes. Para isso utilizei a interação entre abelhas coletoras de óleo e Krameria (Krameriaceae) como sistema modelo. A tese abrange a história natural do sistema e manipulações experimentais in situ que deram suporte à investigação sobre integração floral no contexto multipopulacional. No primeiro capítulo, estudei a biologia da polinização de Krameria tomentosa, listando as espécies de visitantes florais associadas a suas flores. Assim, mostrei que essa espécie depende de seus polinizadores para o sucesso na polinização e que a maioria das abelhas coletoras de óleo associada a suas flores pertence ao gênero Centris (Centridini). No entanto, observei uma alta frequência de abelhas coletoras de pólen nessa espécie que parecem contribuir com a manutenção da polinização na população. No segundo capítulo, mostrei que há uma variação geográfica na assembleia de polinizadores de K. grandiflora que inclui diferentes comportamentos e ajustes à morfologia floral da espécie. Desse modo, testei a significância funcional das três estruturas especializadas das flores de Krameria (cálice conspícuo, pétalas petaloides e elaióforos) em dois cenários contrastantes de ajuste entre a arquitetura floral e o polinizador. No entanto, diferenças não foram detectadas. O ajuste mecânico que os elaióforos provêm parece essencial para o sucesso na polinização no grupo. No terceiro capítulo, demonstrei que populações similares no padrão de correlação de seus caracteres florais, apresentam composição e diversidade funcional de polinizadores semelhantes, sugerindo que diferenças na morfologia combinadas à abundância de polinizadores influenciam o padrão de integração fenotípica. Portanto, esses resultados mostram uma situação em que a variação geográfica na assembleia de polinizadores parece promover a diferenciação da estrutura correlacional do fenótipo floral / In this study, I investigate some aspects of the evolutionary ecology of a plant-pollinator interaction, by evaluating the floral phenotype under geographically divergent selective forces. For this, I used the interaction between oil-collecting bees and Krameria (Krameriaceae) as a system model. This thesis comprises the natural history of the studied system and manipulative experiments in situ to support the investigation on the phenotypic integration in a multipopulation context. In the first chapter, I studied the pollination biology of Krameria tomentosa, listing the flower visitor species associated to its flowers. Thus, I showed that this species depends on their pollinator for pollination success and that most oil-collecting bees recorded belongs to Centris genus (Centridini). However, I observed a high frequency of pollen-collecting bees on this species which might contribute to pollination maintenance in the population. In the second chapter, I showed that there is a geographic variation in the pollinator assemblage of K. grandiflora which includes different behavior and matching to Krameria floral architecture. Thus, I tested the functional significance of the three specialized structures of Krameria flowers (showy calyx, petaloid petals and elaiophores) in two contrasting pollinator-matching scenarios; however, no differences were detected. The mechanical fit provided by the elaiophores might be a keystone for the pollination success in Krameria. O ajuste mecânico que os elaióforos provêm parece essencial para o sucesso na polinização no grupo. In the third chapter, I demonstrated that populations with similar patterns of floral trait correlation comprise similar pollinator composition and functional diversity, suggesting that differences in pollinator morphology combined to abundance influences the pattern of phenotypic integration. Therefore, these results show a condition in which geographic variation in pollinator assemblage might provide divergence in the phenotypic correlation structure

Orientador: Reinaldo José da Silva / Abstract: Species differ in their environmental preferences, leading to processes in the community based in gradient variations that decrease as the distance increases. This process diminishes faster in heterogeneous landscapes, especially in solid areas of bands like South American open diagonally, that is characterized by horizontal stratification environments, presenting a landscape mosaic that extends from the Caatinga to the regions of Chaco, through the Pantanal. The Cerrado, Pantanal and Caatinga are characterized by great diversity of vertebrate anuran species, including the host Leptodactylus fuscus. These regions are inserted in the open diagonal South American. The composition and the relationship between parasite-host infra-populations of helminth species associated with L. fuscus specimens were described in three different regions of Brazil. Amphibians are found in a variety of habitats and exhibit different reproductive and behavioral patterns, considered good models to study parasitology. The study evaluated if there is a decay on the similarity between geographically distant communities and concluded that these two variables are positively associated. This study assessed 155 hosts and found a total of 16 taxa: Aplectana membranosa, Aplectana pintoi, Schankiana formosula, Cosmocerca podicipinus, Oswaldocruzia lopesi, Oxyascaris necopinus, Glypthelmins linguatula, Catadiscus cf. marinholutzi, Physaloptera sp., Physalopteroides sp., Rhabdias sp., metacercariae (Diplostomid... (Complete abstract click electronic access below) / Resumo: As espécies diferem em suas preferências ambientais, isto conduz a processos na comunidade baseados em variações de gradiente que decrescem com o aumento da distância, sobretudo em faixas de áreas contínuas como a diagonal aberta sul-americana, apresentando um mosaico paisagístico que se estende desde a Caatinga até as regiões do Chaco. O Cerrado, Pantanal e Caatinga são caracterizados pela grande diversidade de espécies de vertebrados anuros, incluindo o hospedeiro Leptodactylus fuscus, e estas regiões estão inseridas na diagonal aberta Sul Americana. Foi descrita a composição e a relação entre parasita-hospedeiro de infra-populações das espécies de helmintos associados com espécimes do Leptodactylus fuscus em três regiões diferentes do Brasil. Os anfíbios são encontrados em uma variedade de habitats e exibem diversos padrões reprodutivos e comportamentais, por isso são considerados bons modelos de estudo para a parasitologia. O trabalho avaliou se ha um decaimento na similaridade entre comunidades geograficamente distantes, e concluiu que estas duas variáveis se associam positivamente. Foram avaliados 155 espécimes de hospedeiros totalizando 16 taxas de helmintos, Aplectana membranosa, Aplectana pintoi, Schankiana formosula, Cosmocerca podicipinus, Oswaldocruzia lopesi, Oxyascaris necopinus, Glypthelmins linguatula, Catadiscus cf. marinholutzi, Physaloptera sp., Physalopteroides sp., Rhabdias sp., metacercárias da Família Diplostomidae, nematodas da Família Cosmocercidae, ... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

La symétrie conforme impose de très fortes contraintes sur les théories quantiques des champs. En deux dimensions, l’algèbre des symétries conformes est infinie, et les théories conformes bidimensionnelles peuvent être complètement résolubles, dans le sens où toutes leurs fonctions de corrélation peuvent être calculées. Ces théories ont un grand domaine d'application, de la théorie des cordes jusqu'aux systèmes critiques en physique statistique, et elles ont été largement étudiées pendant les dernières décennies.Dans cette thèse nous étudions les théories conformes bidimensionnelles dont l’algèbre de symétrie est celle de Virasoro, en suivant l'approche connue sous le nom de bootstrap conforme. Sous l'hypothèse de l'existence de champs dégénérés, nous généralisons le bootstrap conforme analytique aux théories avec des spectres non-diagonaux. Nous écrivons les équations qui déterminent les constantes de structure, et nous trouvons des solutions explicites en termes de fonctions spéciales. Nous validons ces résultats en faisant des calculs numériques des fonctions de corrélation à quatre points dans des modèles minimaux diagonaux et non-diagonaux, et en vérifiant que la symétrie de croisement est respectée.En outre, nous construisons une proposition pour une famille de théories conformes non-diagonales et non-rationnelles pour toute charge centrale telle que Re(c) < 13. Cette proposition est motivée par les limites des spectres des modèles minimaux de la série D. Nous réalisons des calculs numériques des fonctions à quatre points dans ces théories, et nous trouvons qu'elles obéissent à la symétrie de croisement. Ces théories peuvent être interprétées comme des extensions non-diagonales de la théorie de Liouville. / Conformal symmetry imposes very strong constraints on quantum field theories. In two dimensions, the conformal symmetry algebra is infinite-dimensional, and two-dimensional conformal field theories can be completely solvable, in the sense that all their correlation functions may be computed. These theories have an ample range of applications, from string theory to critical phenomena in statistical physics, and they have been widely studied during the last decades.In this thesis we study two-dimensional conformal field theories with Virasoro algebra symmetry, following the conformal bootstrap approach. Under the assumption that degenerate fields exist, we provide an extension of the analytic conformal bootstrap method to theories with non-diagonal spectrums. We write the equations that determine structure constants, and find explicit solutions in terms of special functions. We validate this results by numerically computing four-point functions in diagonal and non-diagonal minimal models, and verifying that crossing symmetry is satisfied.In addition, we build a proposal for a family of non-diagonal, non-rational conformal field theories for any central charges such that Re(c) < 13. This proposal is motivated by taking limits of the spectrum of D-series minimal models. We perform numerical computations of four-point functions in these theories, and find that they satisfy crossing symmetry. These theories may be understood as non-diagonal extensions of Liouville theory.

Reports on undergraduate medical education in the recent decade clearly point towards a need for greater integration of content in the medical curriculum. The pedagogy of an integrated curriculum embraces many models of integration, representing a continuum where full integration sits at one end and disciplinebased teaching at the other, with many intermediate steps between the two extremes. A vertically integrated curriculum seeks to bridge the preclinical and clinical divide in content by teaching the content concurrently rather than sequentially, but still retaining discipline boundaries. A horizontally integrated curriculum seeks to further break down the distinctions between the basic and clinical sciences, with the early years of the program focusing on the basic sciences and introducing clinical features into the program wherever possible as part of a gradual shift to a more continued collaborative clinical focus. At the College of Medicine, University of Saskatchewan, the overall redesigned curricular program will be phased in over the next four years of the curriculum, with a greater emphasis towards an integrated approach of the teaching and learning of human disease. In the first year, this has led to the creation of a patchwork quilt teaching style, where a cross disciplinary functional system incorporates elements of the traditional basic science components of anatomy, physiology, embryology, and histology, and an introduction of core general pathological concepts in a vertical and horizontal integrated fashion. <p>The main objective of this research, detailed in Chapter 1, was to investigate the advantages and disadvantages of the two models of horizontal and vertical integration of the reorganized structural teaching of pathology through an analysis of the perceptions of medical educators and first- and second-year students in the undergraduate curriculum at the College of Medicine, and based contextually within a theoretical framework of the newly designed medical curriculum. <p>In this context, the literature review in Chapter 2 focused on four major areas that are the underpinnings of the pedagogy of pathology teaching in the undergraduate medical curriculum: (a) integration concepts in relation to medical education; (b) the practice of pathology teaching in the past, present, and future; (c) theories of curricular integration; and (d) its effects on the student learning environment. This resulted in the development of the pre-research conceptual framework for this study. <p>The in-service monitoring research design for this study included a triangulation of research methodologies using multiple data sources, multiple subjects, and multiple data collection techniques using comparative qualitative and quantitative research inquiry techniques. Data collected from the semi-structured interviews of the medical faculty provided not only an understanding of the educators perceptions towards the integrated curriculum, but also some insight towards their feelings of respect, power, and identity in this new integrative environment. Personal perceptions of fear, apathy, and stress and perceptions regarding accountability and sustainability of this integrative process were also observed as arising from this educational intervention. <p>Quantitative data analysis collected from the first-year student survey questionnaires derived the following grand mean responses with respect to the vertical integration of pathology teachings: student learning satisfaction with integration (3.6); the learning environment (3.8); student engagement (3.3); and student stress (2.9). The grand mean responses to horizontal integration showed a similar trend: student learning satisfaction (3.7); learning environment (4); student engagement (3.5); and student stress (3). Perceptions of the second-year medical students to horizontal integration of pathology teachings were comparable: student learning satisfaction (3.7); learning environment (4.2); student engagement (3.7); and student stress (3.1). A comparison of first- and second-year medical students showed a significant difference (p<0.05) with respect to the domains of student engagement with active independent learning. This difference may, perhaps, be directly related to the level of maturity of the first- versus second-year students, coupled with the receptiveness, awareness, and familiarity of the integration process between the two groups. There were no perceived differences between the horizontal and vertical integrative learning environments. Likewise, inter-modular and inter-system components within the vertical and horizontal integration did not demonstrate any major differences. These results are explored in greater detail in Chapters 4 and 5.<p>One of the noteworthy findings of this study was the statistically significant difference between the perceptions of first-year medical and dental students in both vertical and horizontal integrative environments in many domains, including student learning satisfaction (p<0.001); learning environment (p<0.001); and student engagement (p<0.01). There was no difference in student stress perceptions between the two groups of first-year students. The main theme linking these disparities seemed to be related to a lack of academic and vocational relevance of the undergraduate medical course teachings to the inter-professional composite cohort of dental students. This has led to the creation of an independent course dedicated to first-year dental students. This rapid in-service responsive evaluation thus recognized a major immediate dissatisfaction, resulting in curricular program change. Other curricular changes are underway to address student concerns of ineffective curricular content and time management. An unexpected emergent theme of this study was the recognition of a perception gap between students and faculty medical educators. This is probably nested in complex factors, such as generational learning differences and attitudes towards the learning environment, which are beyond the research scope of this study.<p>In conclusion, the results of this study strongly supports an overall balanced composite curricular design, including facets of horizontal, vertical, and diagonal integration that meet the needs of the student learner and satisfy the expectations of the medical faculty as the best practice plan for the instruction of pathology in the newly designed integrated medical curriculum. As learning is the central function of all education, perhaps the future of successful effective medical educational learning environments are those in which an intergenerational component of students and instructors can engage as true joint partners in curriculum organization to provide the right balance between faculty expectations and student learner needs.

Reports on undergraduate medical education in the recent decade clearly point towards a need for greater integration of content in the medical curriculum. The pedagogy of an integrated curriculum embraces many models of integration, representing a continuum where full integration sits at one end and disciplinebased teaching at the other, with many intermediate steps between the two extremes. A vertically integrated curriculum seeks to bridge the preclinical and clinical divide in content by teaching the content concurrently rather than sequentially, but still retaining discipline boundaries. A horizontally integrated curriculum seeks to further break down the distinctions between the basic and clinical sciences, with the early years of the program focusing on the basic sciences and introducing clinical features into the program wherever possible as part of a gradual shift to a more continued collaborative clinical focus. At the College of Medicine, University of Saskatchewan, the overall redesigned curricular program will be phased in over the next four years of the curriculum, with a greater emphasis towards an integrated approach of the teaching and learning of human disease. In the first year, this has led to the creation of a patchwork quilt teaching style, where a cross disciplinary functional system incorporates elements of the traditional basic science components of anatomy, physiology, embryology, and histology, and an introduction of core general pathological concepts in a vertical and horizontal integrated fashion. <p>The main objective of this research, detailed in Chapter 1, was to investigate the advantages and disadvantages of the two models of horizontal and vertical integration of the reorganized structural teaching of pathology through an analysis of the perceptions of medical educators and first- and second-year students in the undergraduate curriculum at the College of Medicine, and based contextually within a theoretical framework of the newly designed medical curriculum. <p>In this context, the literature review in Chapter 2 focused on four major areas that are the underpinnings of the pedagogy of pathology teaching in the undergraduate medical curriculum: (a) integration concepts in relation to medical education; (b) the practice of pathology teaching in the past, present, and future; (c) theories of curricular integration; and (d) its effects on the student learning environment. This resulted in the development of the pre-research conceptual framework for this study. <p>The in-service monitoring research design for this study included a triangulation of research methodologies using multiple data sources, multiple subjects, and multiple data collection techniques using comparative qualitative and quantitative research inquiry techniques. Data collected from the semi-structured interviews of the medical faculty provided not only an understanding of the educators perceptions towards the integrated curriculum, but also some insight towards their feelings of respect, power, and identity in this new integrative environment. Personal perceptions of fear, apathy, and stress and perceptions regarding accountability and sustainability of this integrative process were also observed as arising from this educational intervention. <p>Quantitative data analysis collected from the first-year student survey questionnaires derived the following grand mean responses with respect to the vertical integration of pathology teachings: student learning satisfaction with integration (3.6); the learning environment (3.8); student engagement (3.3); and student stress (2.9). The grand mean responses to horizontal integration showed a similar trend: student learning satisfaction (3.7); learning environment (4); student engagement (3.5); and student stress (3). Perceptions of the second-year medical students to horizontal integration of pathology teachings were comparable: student learning satisfaction (3.7); learning environment (4.2); student engagement (3.7); and student stress (3.1). A comparison of first- and second-year medical students showed a significant difference (p<0.05) with respect to the domains of student engagement with active independent learning. This difference may, perhaps, be directly related to the level of maturity of the first- versus second-year students, coupled with the receptiveness, awareness, and familiarity of the integration process between the two groups. There were no perceived differences between the horizontal and vertical integrative learning environments. Likewise, inter-modular and inter-system components within the vertical and horizontal integration did not demonstrate any major differences. These results are explored in greater detail in Chapters 4 and 5.<p>One of the noteworthy findings of this study was the statistically significant difference between the perceptions of first-year medical and dental students in both vertical and horizontal integrative environments in many domains, including student learning satisfaction (p<0.001); learning environment (p<0.001); and student engagement (p<0.01). There was no difference in student stress perceptions between the two groups of first-year students. The main theme linking these disparities seemed to be related to a lack of academic and vocational relevance of the undergraduate medical course teachings to the inter-professional composite cohort of dental students. This has led to the creation of an independent course dedicated to first-year dental students. This rapid in-service responsive evaluation thus recognized a major immediate dissatisfaction, resulting in curricular program change. Other curricular changes are underway to address student concerns of ineffective curricular content and time management. An unexpected emergent theme of this study was the recognition of a perception gap between students and faculty medical educators. This is probably nested in complex factors, such as generational learning differences and attitudes towards the learning environment, which are beyond the research scope of this study.<p>In conclusion, the results of this study strongly supports an overall balanced composite curricular design, including facets of horizontal, vertical, and diagonal integration that meet the needs of the student learner and satisfy the expectations of the medical faculty as the best practice plan for the instruction of pathology in the newly designed integrated medical curriculum. As learning is the central function of all education, perhaps the future of successful effective medical educational learning environments are those in which an intergenerational component of students and instructors can engage as true joint partners in curriculum organization to provide the right balance between faculty expectations and student learner needs.

¡@¡@This study aims to investigate the theories and empirical performance of the futures and options margin systems currently used in the domestic and international exchange houses. The current system used in Taiwan Futures Exchange (TAIFEX) is strategy-based rather than portfolio-based or and contract risk-based. It is no longer compliant with the development of the futures market. Therefore, it is suggested that TAIFEX should employ international experiences to adopt a portfolio-based and VaR-based margin system so as to meet the need of the local trading feature that portfolios contain both stock futures and stock options. ¡@¡@This study integrates scenario simulation and the diagonal model to propose a new model, called Beta-Simulation, to calculate the margins for portfolios containing stock options, index futures, and stocks. The proposed model can not only simplify the inter-commodity spread in SPAN but also theoretically improve the drawback of TIMS of using a simple credit offset multiplier. In the empirical test, back testing is performed on the margins calculated by Beta-Simulation with historic data of portfolios with stock options, and other common margin systems are also included in the test for comparison. ¡@¡@The empirical results reveal that only SPAN and Beta-Simulation can save approximately 12%~42% margin requirements for portfolios containing stock options, but under the same protection degree, Beta-Simulation requires significantly lower margins and a simpler calculation process than SPAN. Therefore, the proposed model is a better model of calculating margins and VaR for portfolios containing stock options.

The Poincaré series, Py(f) of a polynomial f was first introduced by Borevich and Shafarevich in [BS66], where they conjectured, that the series is always rational. Denef and Igusa independently proved this conjecture. However it is still of interest to explicitly compute the Poincaré series in special cases. In this direction several people looked at diagonal polynomials with restrictions on the coefficients or the exponents and computed its Poincaré series. However in this dissertation we consider a general diagonal polynomial without any restrictions and explicitly compute its Poincaré series, thus extending results of Goldman, Wang and Han. In a separate chapter some new results are also presented that give a criterion for an element to be an mth power in a complete discrete valuation ring.

Motivado por la entrada en vigencia de la nueva norma chilena de hormigón armado, NCh430.Of2008, que en el presente año incorporó nuevas exigencias sobre el diseño con barras diagonales en dinteles cortos, este trabajo tuvo como objetivo la búsqueda y evaluación de diseños alternativos a esta disposición. Se realizó una revisión del estado del arte sobre trabajos relacionados con el tema desarrollados en los últimos años y se dan a conocer cuatro líneas de investigación a nivel internacional. El tipo de soluciones propuestas comprenden el uso de placas de acero, vigas doble T, uso de fibra de acero en vigas prefabricadas de hormigón armado y otras configuraciones de refuerzo en hormigón armado tradicional. Posteriormente, se hizo una evaluación y discusión acerca de cual de las alternativas es la más apropiada en reemplazo de la armadura diagonal. Se fundamentó y escogió la armadura romboidal como la alternativa más idónea. Se hizo un estudio analítico para estimar y comparar el comportamiento no lineal de esta alternativa respecto de la solución con armadura diagonal. Esto comprendió la modelación de dos muros acoplados por dinteles en toda su altura, donde estos elementos quedaron representados a través de una curva elastoplástica, en el contexto de un análisis “pushover”. Como resultado se obtuvo que la curva de capacidad de la estructura estudiada con la armadura romboidal mostró un buen desempeño de la alternativa tanto para desplazamientos laterales bajos a moderados, siendo deficiente su desempeño solo hacia el final del análisis “pushover”, cuando la estructura está sometida a desplazamientos laterales de gran magnitud. Esto se refleja también en el punto de desempeño de la estructura, donde ambas soluciones se comportan de manera similar para la demanda sísmica esperada.

No description available.