Made available in DSpace on 2015-03-26T13:39:52Z (GMT). No. of bitstreams: 1 texto completo.pdf: 904676 bytes, checksum: 4300f9baf42cbd733adbef5d012aab22 (MD5) Previous issue date: 2012-08-06 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Despite its potential, the physic nut (Jatropha curcas L.) is still in domestication and the increase of its viability depends on a quantitative yield increase. The uneven fruit maturation and the low yield have been considered as the main limitations of this crop. The objectives of this study were to characterize the yield potential and to estimate the genetic parameters of the grain yield components of physic nut half-sibs families at the 20, 30 and 40 years after planting, in order to quantify the genetic progress with the plant selection. With this objective 16 half-sibs families were evaluated using a randomized block design with three blocks and eight replications. The following traits were evaluated: grain yield, number of bunches per plant, number of fruits per bunch, maturation index, height and projection of plant crowns. The grain yield traits showed predominant genetic control. However, the environmental effect was determinant to the fruit maturation and management strategies have higher potential to improve this trait. The genetic progress with the vegetative propagation of the selected genotypes was 33.3%, 41.6% and 56.7% at the 20, 30 and 40 years after planting, respectively. The genetic progress estimated with the vegetative propagation of the superior genotypes indicates that the non-additive genetic variance have lower importance to the trait expression. The development of new materials may consider strategies for increase of the genetic variability, as breeding among divergent plants with better agronomic traits. Key words: Jatropha curcas L., estimates genetic parameters, biodiesel production. / Apesar das suas potencialidades, o pinhão-manso (Jatropha curcas L.) encontra-se em processo de domesticação e o incremento da sua viabilidade econômica, social e ambiental depende de um incremento quantitativo de produtividade. A maturação desuniforme dos frutos e a baixa produtividade de grãos têm limitado a utilização desse cultivo para a produção de biodiesel. Os objetivos deste trabalho foram caracterizar o potencial produtivo e estimar os parâmetros genéticos e o progresso com seleção de componentes de produção de famílias de meias irmãs de pinhão-manso, no 20, 30 e 40 anos pós-plantio. Avaliaram-se 16 famílias de meias irmãs em blocos casualizados, com três blocos e oito repetições. As seguintes características foram avaliadas: produção de grãos, número de cachos por planta, número de frutos por cacho, maturação dos frutos, altura e projeção de copa das plantas. Os principais componentes da produção dessa oleaginosa apresentaram controle genético predominante. No entanto, o efeito ambiental foi o principal determinante da uniformidade de maturação dos frutos, desta forma, estratégias de manejo têm maior potencial para impactar na concentração da produção de frutos dessa oleaginosa. O progresso genético da produção de grãos com a propagação vegetativa das plantas selecionadas foi de 33,3%, 41,6% e 56,7% no 20, 30 e 40 anos pós-plantio, respectivamente. O ganho de seleção obtido com a propagação vegetativa das plantas selecionadas indica que os componentes não aditivos da variância apresentam menor influência na resposta das características. O desenvolvimento de novos materiais deve considerar estratégias de geração de variabilidade utilizando cruzamentos entre plantas divergentes e de melhores características agronômicas.

The heart is one the most important organs in the human body and many other live creatures. The electrical activity in the heart controls the heart function, and many heart diseases are linked to the abnormalities in the electrical activity in the heart. Mathematical equations and computer simulation can be used to model the electrical activity in the heart. The heart models are challenging to solve because of the complexity of the models and the huge size of the problems. Several cell models have been proposed to model the electrical activity in a single heart cell. These models must be coupled with a heart model to model the electrical activity in the entire heart. The bidomain model is a popular model to simulate the propagation of electricity in myocardial tissue. It is a continuum-based model consisting of non-linear ordinary differential equations (ODEs) describing the electrical activity at the cellular scale and a system of partial differential equations (PDEs) describing propagation of electricity at the tissue scale. Because of this multi-scale, ODE/PDE structure of the model, splitting methods that treat the ODEs and PDEs in separate steps are natural candidates as numerical methods. First, we need to solve the problem at the cellular scale using ODE solvers. One of the most popular methods to solve the ODEs is known as the Rush-Larsen (RL) method. Its popularity stems from its improved stability over integrators such as the forward Euler (FE) method along with its easy implementation. The RL method partitions the ODEs into two sets: one for the gating variables, which are treated by an exponential integrator, and another for the remaining equations, which are treated by the FE method. The success of the RL method can be understood in terms of its relatively good stability when treating the gating variables. However, this feature would not be expected to be of benefit on cell models for which the stiffness is not captured by the gating equations. We demonstrate that this is indeed the case on a number of stiff cell models. We further propose a new partitioned method based on the combination of a first-order generalization of the RL method with the FE method. This new method leads to simulations of stiff cell models that are often one or two orders of magnitude faster than the original RL method. After solving the ODEs, we need to use bidomain solvers to solve the bidomain model. Two well-known, first-order time-integration methods for solving the bidomain model are the semi-implicit method and the Godunov operator-splitting method. Both methods decouple the numerical procedure at the cellular scale from that at the tissue scale but in slightly different ways. The methods are analyzed in terms of their accuracy, and their relative performance is compared on one-, two-, and three-dimensional test cases. As suggested by the analysis, the test cases show that the Godunov method is significantly faster than the semi-implicit method for the same level of accuracy, specifically, between 5 and 15 times in the cases presented. Second-order bidomain solvers can generally be expected to be more effective than first-order bidomain solvers under normal accuracy requirements. However, the simplest and the most commonly applied second-order method for the PDE step, the Crank-Nicolson (CN) method, may generate unphysical oscillations. We investigate the performance of a two-stage, L-stable singly diagonally implicit Runge-Kutta method for solving the PDEs of the bidomain model and present a stability analysis. Numerical experiments show that the enhanced stability property of this method leads to more physically realistic numerical simulations compared to both the CN and Backward Euler (BE) methods.