883 resultados para Reasoning about variation and distribution


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Nowadays computing platforms consist of a very large number of components that require to be supplied with diferent voltage levels and power requirements. Even a very small platform, like a handheld computer, may contain more than twenty diferent loads and voltage regulators. The power delivery designers of these systems are required to provide, in a very short time, the right power architecture that optimizes the performance, meets electrical specifications plus cost and size targets. The appropriate selection of the architecture and converters directly defines the performance of a given solution. Therefore, the designer needs to be able to evaluate a significant number of options in order to know with good certainty whether the selected solutions meet the size, energy eficiency and cost targets. The design dificulties of selecting the right solution arise due to the wide range of power conversion products provided by diferent manufacturers. These products range from discrete components (to build converters) to complete power conversion modules that employ diferent manufacturing technologies. Consequently, in most cases it is not possible to analyze all the alternatives (combinations of power architectures and converters) that can be built. The designer has to select a limited number of converters in order to simplify the analysis. In this thesis, in order to overcome the mentioned dificulties, a new design methodology for power supply systems is proposed. This methodology integrates evolutionary computation techniques in order to make possible analyzing a large number of possibilities. This exhaustive analysis helps the designer to quickly define a set of feasible solutions and select the best trade-off in performance according to each application. The proposed approach consists of two key steps, one for the automatic generation of architectures and other for the optimized selection of components. In this thesis are detailed the implementation of these two steps. The usefulness of the methodology is corroborated by contrasting the results using real problems and experiments designed to test the limits of the algorithms.

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The intergenic spacer (IGS) region of the ribosomal DNA was cloned and sequenced in eight species within the Gibberella fujikuroi species complex with anamorphs in the genus Fusarium , a group that includes the most relevant toxigenic species. DNA sequence analyses revealed two categories of repeated elements: long repeats and short repeats of 125 and 8 bp, respectively. Long repeats were present in two copies and were conserved in all the species analyzed, whereas different numbers of short repeat elements were observed, leading to species-specific IGS sequences with different length. In Fusarium subglutinans and Fusarium nygamai , these differences seemed to be the result of duplication and deletion events. Here, we propose a model based on unequal crossing over that can explain these processes. The partial IGS sequence of 22 Fusarium proliferatum isolates was also obtained to study variation at the intraspecific level. The results revealed no differences in terms of number or pattern of repeated elements and detected frequent gene conversion events. These results suggest that the homogenization observed at the intraspecific level might not be achieved primarily by unequal crossing-over events but rather by processes associated with recombination such as gene conversion events.

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Análisis del riesgo volcánico. We show the preliminary results of the study of 561 volcanic bombs ejected from a pyroclastic cone during the 1730-1736 Timanfaya eruption (Lanzarote, Canary Islands). This cone displays the highest concentration of big bombs (major axis higher than 1 m) of Timanfaya. More than 560 bombs have been studied to calculate their reach. The results suggest that bombs of 1t have a reach of 409 m, while bombs up to 28 t have a reach of 248 m. These data may be used to define a security area once a vent has been opened, but also to calculate other data such the initial velocity of ejection. The geomorphological analysis and the study of the deposits also contribute to better understand an undocumented episode of the Timanfaya eruption and also provide important data for volcanic bombs modeling for volcanic hazard analysis.

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Multiple robot, single operator scenarios suppose a challenge in terms of human factors. Two relevant issues are keeping the situational awareness and managing the workload of operators. In order to address these problems, this work analyses the management of information and commands in multi-robot missions. About the information, this paper proposes a selection based on mission and operator states. Regarding the commands, this work reflects about the levels of automation and the methods of commanding.

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Thirty-seven varieties of a Mediterranean durum wheat collection grown in Tunisia and Spain were analysed for their allelic composition in prolamins, as well as their protein concentration, sodium dodecyl sulphate sedimentation (SDSS) test and mixograph parameters. Genotype was a greater source of variation in all measurements than locality. Uncommon high and low molecular glutenin subunits (HMW-GS and LMW-GS) were found (V and 2? subunits at Glu-A1, 13 þ 16 at Glu-B1, 5* subunit and ax allele at Glu-A3). The rare combinations 2 þ 4þ14 þ 18 and 8 þ 9þ13 þ 16þ18 subunits at the Glu-B3 locus were found. Glu-A3ax had a positive influence on SDSS and mixograph parameters. Of all the prolamins, those that have the B-LMW-GS composition aaa (for Glu-A3, Glu-B3 and Glu-B2 loci, respectively), when associated with the Glu-A1c and Glu-B1d gave the best semolina quality. By contrast, semolina quality is poor when this same composition is associated with the Glu-A1c and Glu-B1e and even poorer when associated with the Glu-A1c and Glu-B1f. In addition, the cultivars with B-LMW-GS allelic composition aab (for Glu-A3, Glu-B3 and Glu-B2 loci, respectively), when associated with the Glu- A1c and Glu-B1d, gave high quality, whereas when associated with the Glu-A1c and Glu-B1e or with Glu- A1o and Glu-B1f, the quality was very poor.

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A number of confusions plague the debate concerning religion and evolution. Included here are the belief that religion and science must be incompatible and the thesis that evolution is evidence for atheism. Clearing up these confusions helps remove obstacles to genuine dialogue, while acknowledging that difficulties remain.