La bio-informatique est un champ pluridisciplinaire qui utilise la biologie, l’informatique, la physique et les mathématiques pour résoudre des problèmes posés par la biologie. L’une des thématiques de la bio-informatique est l’analyse des séquences génomiques et la prédiction de gènes d’ARN non codants. Les ARN non codants sont des molécules d’ARN qui sont transcrites mais pas traduites en protéine et qui ont une fonction dans la cellule. Trouver des gènes d’ARN non codants par des techniques de biochimie et de biologie moléculaire est assez difficile et relativement coûteux. Ainsi, la prédiction des gènes d’ARNnc par des méthodes bio-informatiques est un enjeu important. Cette recherche décrit un travail d’analyse informatique pour chercher des nouveaux ARNnc chez le pathogène Candida albicans et d’une validation expérimentale. Nous avons utilisé comme stratégie une analyse informatique combinant plusieurs logiciels d’identification d’ARNnc. Nous avons validé un sous-ensemble des prédictions informatiques avec une expérience de puces à ADN couvrant 1979 régions du génome. Grace à cette expérience nous avons identifié 62 nouveaux transcrits chez Candida albicans. Ce travail aussi permit le développement d’une méthode d’analyse pour des puces à ADN de type tiling array. Ce travail présente également une tentation d’améliorer de la prédiction d’ARNnc avec une méthode se basant sur la recherche de motifs d’ARN dans les séquences. / Bioinformatics is a multidisciplinary field that uses biology, computer science, physics and mathematics to solve problems in biology. One of the topics of bioinformatics is the analysis of genomic sequences and prediction of genes from non-coding RNA (ncRNA). The non-coding RNAs are RNA molecules that are transcribed but not translated into protein and have a function in the cell. The use of biochemistry and molecular biology techniques in order to find non-coding RNA genes is rather difficult and relatively expensive. Thus, the prediction of genes by bioinformatics methods is an important issue. This research describes a computer analysis to search for new ncRNA in the pathogen Candida albicans and an experimental validation. The strategy used was to combine several algorithms and to validate a subset of computer predictions with a microarray experience covering 1979 regions of the genome. We have identified 62 new transcripts in Candida albicans. We have also developed an analytical method for tiling array and attempted to improve the prediction of ncRNAs this with a method based on the search of RNA motifs in the sequences.

La bio-informatique est un champ pluridisciplinaire qui utilise la biologie, l’informatique, la physique et les mathématiques pour résoudre des problèmes posés par la biologie. L’une des thématiques de la bio-informatique est l’analyse des séquences génomiques et la prédiction de gènes d’ARN non codants. Les ARN non codants sont des molécules d’ARN qui sont transcrites mais pas traduites en protéine et qui ont une fonction dans la cellule. Trouver des gènes d’ARN non codants par des techniques de biochimie et de biologie moléculaire est assez difficile et relativement coûteux. Ainsi, la prédiction des gènes d’ARNnc par des méthodes bio-informatiques est un enjeu important. Cette recherche décrit un travail d’analyse informatique pour chercher des nouveaux ARNnc chez le pathogène Candida albicans et d’une validation expérimentale. Nous avons utilisé comme stratégie une analyse informatique combinant plusieurs logiciels d’identification d’ARNnc. Nous avons validé un sous-ensemble des prédictions informatiques avec une expérience de puces à ADN couvrant 1979 régions du génome. Grace à cette expérience nous avons identifié 62 nouveaux transcrits chez Candida albicans. Ce travail aussi permit le développement d’une méthode d’analyse pour des puces à ADN de type tiling array. Ce travail présente également une tentation d’améliorer de la prédiction d’ARNnc avec une méthode se basant sur la recherche de motifs d’ARN dans les séquences. / Bioinformatics is a multidisciplinary field that uses biology, computer science, physics and mathematics to solve problems in biology. One of the topics of bioinformatics is the analysis of genomic sequences and prediction of genes from non-coding RNA (ncRNA). The non-coding RNAs are RNA molecules that are transcribed but not translated into protein and have a function in the cell. The use of biochemistry and molecular biology techniques in order to find non-coding RNA genes is rather difficult and relatively expensive. Thus, the prediction of genes by bioinformatics methods is an important issue. This research describes a computer analysis to search for new ncRNA in the pathogen Candida albicans and an experimental validation. The strategy used was to combine several algorithms and to validate a subset of computer predictions with a microarray experience covering 1979 regions of the genome. We have identified 62 new transcripts in Candida albicans. We have also developed an analytical method for tiling array and attempted to improve the prediction of ncRNAs this with a method based on the search of RNA motifs in the sequences.

Este estudo teve como objetivo analisar a evolução dos custos de produção e produtividade em lavouras do município de Cruz Alta - RS, que cultivam soja, milho, trigo e aveia sob plantio direto por um longo período de tempo. A permanência na adoção do plantio direto poderia, além dos benefícios comumente citados de melhorias ambientais, reduzir os custos e aumentar a produtividadedas lavouras, principalmente a partir do quinto ano. Para verificar a veracidade desta suposição, foram coletadas informações referentesa safra 96/97 junto a produtores que se encontram em diferentes anos de adoção de plantio direto. Os resultados mostram que para a cultura da soja a hi~ótese se confirmou pois, os custoslha caíram e a produtividade aumentou consideravelmente. O milho apresentou custos relativamente constantes, mas a ProdutiVi~ aumentou. O trigo por não ser cultivado em número significativo de propriedades, não apresentou tendência definida e, a aveia evidenciou aumento nos custos, isto se justifica pela intensificação dos tratos culturais. A produtividade desta cultura não foi mensurada na íntegra pois a produção de grão é apenas uma das formas de receita auferida pelos produtores. Posteriormente foram feitas simulações para analisar a atratividade do investimento na agricultura com a utilização de plantio direto. Observou-se, que, independente do sistema de rotação adotado, o investimento só é viável quando não se considera o custo de oportunidade da terra. Quando este é incluído o retomo sobre o capital investido não ultrapassa a taxa de 6% a. a. / This study aimed at analyzing the evolution of costs of production and productivity of farms in the municipality of Cruz Alta - RS, where soybean, com, wheatand oats have been cultivated with no tilling techniques for a long time. The continuous adoption of no tilling could reduce costs and increase productivityof the farms, mainly after the fifth year, besides its common benefits in improvingthe environment. To verify the truthfulness of this assumption, data were collected in relation to the 96/97 harvest, trom producers who are in different stages of adoption of no tilling. The results show that for soybeans the hypothesis was confirmed, since costs per hectare dropped and productivity increased considerably~ Com presented relatively constant costs, but the productivity increased. Wheat didn't showany definite tendency, since it is not cultivated in a significant number of properties, and oats showed some increase in costs, due to more intensive cultivation methods. The productivity of this culture was not completely measured, as the output of the grains is only one form of measuring the income received by producers. Thereafter, some simulations were made to analyze the ability to attract investment in agriculture with the use of no tilling. It was observed that the investment is viable only when you do not consider the opportunity cost of the land, independent of the rotation system adopted. When this is included the return over capital investment doesn't exceed the rate of 6% annually.

Este estudo teve como objetivo analisar a evolução dos custos de produção e produtividade em lavouras do município de Cruz Alta - RS, que cultivam soja, milho, trigo e aveia sob plantio direto por um longo período de tempo. A permanência na adoção do plantio direto poderia, além dos benefícios comumente citados de melhorias ambientais, reduzir os custos e aumentar a produtividadedas lavouras, principalmente a partir do quinto ano. Para verificar a veracidade desta suposição, foram coletadas informações referentesa safra 96/97 junto a produtores que se encontram em diferentes anos de adoção de plantio direto. Os resultados mostram que para a cultura da soja a hi~ótese se confirmou pois, os custoslha caíram e a produtividade aumentou consideravelmente. O milho apresentou custos relativamente constantes, mas a ProdutiVi~ aumentou. O trigo por não ser cultivado em número significativo de propriedades, não apresentou tendência definida e, a aveia evidenciou aumento nos custos, isto se justifica pela intensificação dos tratos culturais. A produtividade desta cultura não foi mensurada na íntegra pois a produção de grão é apenas uma das formas de receita auferida pelos produtores. Posteriormente foram feitas simulações para analisar a atratividade do investimento na agricultura com a utilização de plantio direto. Observou-se, que, independente do sistema de rotação adotado, o investimento só é viável quando não se considera o custo de oportunidade da terra. Quando este é incluído o retomo sobre o capital investido não ultrapassa a taxa de 6% a. a. / This study aimed at analyzing the evolution of costs of production and productivity of farms in the municipality of Cruz Alta - RS, where soybean, com, wheatand oats have been cultivated with no tilling techniques for a long time. The continuous adoption of no tilling could reduce costs and increase productivityof the farms, mainly after the fifth year, besides its common benefits in improvingthe environment. To verify the truthfulness of this assumption, data were collected in relation to the 96/97 harvest, trom producers who are in different stages of adoption of no tilling. The results show that for soybeans the hypothesis was confirmed, since costs per hectare dropped and productivity increased considerably~ Com presented relatively constant costs, but the productivity increased. Wheat didn't showany definite tendency, since it is not cultivated in a significant number of properties, and oats showed some increase in costs, due to more intensive cultivation methods. The productivity of this culture was not completely measured, as the output of the grains is only one form of measuring the income received by producers. Thereafter, some simulations were made to analyze the ability to attract investment in agriculture with the use of no tilling. It was observed that the investment is viable only when you do not consider the opportunity cost of the land, independent of the rotation system adopted. When this is included the return over capital investment doesn't exceed the rate of 6% annually.

Este estudo teve como objetivo analisar a evolução dos custos de produção e produtividade em lavouras do município de Cruz Alta - RS, que cultivam soja, milho, trigo e aveia sob plantio direto por um longo período de tempo. A permanência na adoção do plantio direto poderia, além dos benefícios comumente citados de melhorias ambientais, reduzir os custos e aumentar a produtividadedas lavouras, principalmente a partir do quinto ano. Para verificar a veracidade desta suposição, foram coletadas informações referentesa safra 96/97 junto a produtores que se encontram em diferentes anos de adoção de plantio direto. Os resultados mostram que para a cultura da soja a hi~ótese se confirmou pois, os custoslha caíram e a produtividade aumentou consideravelmente. O milho apresentou custos relativamente constantes, mas a ProdutiVi~ aumentou. O trigo por não ser cultivado em número significativo de propriedades, não apresentou tendência definida e, a aveia evidenciou aumento nos custos, isto se justifica pela intensificação dos tratos culturais. A produtividade desta cultura não foi mensurada na íntegra pois a produção de grão é apenas uma das formas de receita auferida pelos produtores. Posteriormente foram feitas simulações para analisar a atratividade do investimento na agricultura com a utilização de plantio direto. Observou-se, que, independente do sistema de rotação adotado, o investimento só é viável quando não se considera o custo de oportunidade da terra. Quando este é incluído o retomo sobre o capital investido não ultrapassa a taxa de 6% a. a. / This study aimed at analyzing the evolution of costs of production and productivity of farms in the municipality of Cruz Alta - RS, where soybean, com, wheatand oats have been cultivated with no tilling techniques for a long time. The continuous adoption of no tilling could reduce costs and increase productivityof the farms, mainly after the fifth year, besides its common benefits in improvingthe environment. To verify the truthfulness of this assumption, data were collected in relation to the 96/97 harvest, trom producers who are in different stages of adoption of no tilling. The results show that for soybeans the hypothesis was confirmed, since costs per hectare dropped and productivity increased considerably~ Com presented relatively constant costs, but the productivity increased. Wheat didn't showany definite tendency, since it is not cultivated in a significant number of properties, and oats showed some increase in costs, due to more intensive cultivation methods. The productivity of this culture was not completely measured, as the output of the grains is only one form of measuring the income received by producers. Thereafter, some simulations were made to analyze the ability to attract investment in agriculture with the use of no tilling. It was observed that the investment is viable only when you do not consider the opportunity cost of the land, independent of the rotation system adopted. When this is included the return over capital investment doesn't exceed the rate of 6% annually.

This study was undertaken to develop an analytical model that is capable of predicting the torque requirements of a rotavator fitted with commercially available L-shaped blades. An analytical approach based on the limit equilibrium analysis was used to develop the proposed model. The proposed model was verified by comparing the model and measured torque requirements at predetermined rotavator blade angular positions from the horizontal for a down-cut rotavator. The study findings indicated that there was an optimum set tillage depth for each rotavator configuration and operational conditions at which the resultant horizontal thrust generated was greatest. This unique depth was influenced by the bite length. The validation of the proposed model showed that the predicted and measured torque requirements, at different angular blade positions from the horizontal, correlated reasonably well for all the set tillage depths. As the depth of tillage increased, however, the curve for the measured torque requirements exhibited a cyclic behaviour after the peak torque requirements value had been recorded. The cyclic behaviour was probably due to the re-tilling and the instability of the tool-frame carrier, which increased with the set tillage depth. The knowledge contributed by this research will afford the designers of active tillage tools a better understanding of the operations of the rotavator, particularly in deep tillage. The modelling approach, and instrumentation technique used in this research, can be extended to analyze the performance of rotavators fitted with other types of commercial blades. / Thesis (PhD)--University of Pretoria, 2010. / Civil Engineering / unrestricted