One of the main goals of ecological research is to understand the factors that determine how communities are structured over both space and time. However, our understanding of any system is largely a function of the scale at which we make our observations. Thus, the mechanisms that determine patterns in community structure are likely to change depending on the scale of observation. This thesis explores how environmental variability affects community structure and species performance, and how the resulting patterns change as a function of scale. Specifically, I asses the role of variability in temperature, oxygen, pH, and chloride, on species richness, abundance, diversity, and species performance, at three observational scales: micro-spatial, local temporal, and landscape-temporal scales, in 49 natural erosional rock pool microcosms, located on the northern coast of Jamaica. I found that while environmental variability was not a primary determinant of species richness or abundance, it did play a role in determining species compositions in the pools. I also show that community patterns are strongly affected by the scale of observation. Recognizing scale-dependent changes in community patterns is a prerequisite for predicting the consequences of changes in ecological systems induced by variability in abiotic factors. / Thesis / Master of Science (MS)

One of the main goals of ecological research is to understand the factors that determine how communities are structured over both space and time. However, our understanding of any system is largely a function of the scale at which we make our observations. Thus, the mechanisms that determine patterns in community structure are likely to change depending on the scale of observation. This thesis explores how environmental variability affects community structure and species performance, and how the resulting patterns change as a function of scale. Specifically, I asses the role of variability in temperature, oxygen, pH, and chloride, on species richness, abundance, diversity, and species performance, at three observational scales: micro-spatial, local-temporal, and landscape-temporal scales, in 49 natural erosional rock pool microcosms, located on the northern. coast of Jamaica. I found that while environmental variability was not a primary determinant of species richness or abundance, it did play a role in determining species compositions in the pools. I also show that community patterns are strongly affected by the scale of observation. Recognizing scale-dependent changes in community patterns is a prerequisite for predicting the consequences of changes in ecological systems induced by variability in abiotic factors. / Thesis / Master of Science (MS)

Macrobenthos and macrophytes of the north shore littoral zone of Hamilton Harbour were extensively sampled in late August 1994. Benthic community structure is described, including the presence of several oligochaete and chironomid genera previously unreported in the harbour. Community structure is scale dependent and identifying which spatial scales contribute important structure is a useful step in determining which environmental factors have the greatest impact on the benthic community. This information can be used to plan efficient benthos monitoring programs, and to construct spatially explicit models of the harbour ecosystem. Most of the variation in the data set (approx. 88%) is due to small scale patchiness, probably related to patchiness of the macrophyte community and sediment grain size, as well as biotic processes such as predation and competition. Large scale structure is related to a water depth gradient, probably involving changes in dissolved oxygen concentrations, light attenuation, and sediment grain size. Macrophytes also respond to this gradient. There is little important structuring of the benthos community at intermediate spatial scales. Models of benthic communities in the harbour must deal with spatial pattern effects such as autocorrelation. Additionally, spatial patterns provide information useful for understanding causes of community structure. A method is developed for the spatial pattern analysis of the benthic community data, which allows the simultaneous evaluation of patterns at various scales, with minimal mixing of information between scales. / Thesis / Master of Science (MS)

The objective of this dissertation centers on gaining a better understanding of the structure - property - performance relations of nickel and copper through the advanced multiscale theoretical framework and integrated computational methods. The goal of this dissertation also includes to combine material science and computational mechanics to acquire a transformative understanding of how the different crystal orientations, size scales, and penetration velocities affect plastic deformation and damage behavior of metallic materials during high strain rate (> 103s-1) processes. A multiscale computational framework for understanding plasticity and shearing mechanisms of metallic materials during the high rate process was developed, which for the first time reveals micromechanical insights on how different crystal orientations, size scales, and penetration velocities affect the atomistic simulations which render structure property information for plasticity, shearing and damage mechanisms. The contributions of this dissertation include: (1) Comprehensive understanding of the plasticity and shearing mechanisms between the nickel penetrator and copper target under high strain rates (2) Development of a multiscale study of a nickel penetrator striking a copper plate by employing macroscale simulations and atomistic simulations to better understand the micromechanisms. (3) An essential description of how different crystal orientations, size scales, and strain rates affect the plasticity and shearing mechanisms.

En France métropolitaine, les projets de géothermie haute température pour la production d’électricité sont principalement localisés dans le socle des fossés d’effondrement liés à la mise en place du Rift Ouest Européen. Le socle de ces fossés a été étudié sur deux analogues à l’affleurement sur les épaules du rift : les Vosges du Nord pour le fossé Rhénan et la bordure Est du Massif central pour la fosse de Valence. Cette étude a permis de montrer que le réseau de failles s’organise selon trois ordres de grandeurs de longueurs et d’espacements caractéristiques qui individualisent des blocs structuraux. Les orientations et l’espacement des failles formant ces blocs et la présence ou l’absence de certains ordres de grandeurs sont le résultat de l’héritage anté-rift du socle, ainsi que du mécanisme d’ouverture du bassin. Le potentiel réservoir des formations de socle et de la couverture surincombante a été analysé au regard de ces zones de failles et de l’altération supergène qui affecte le toit du socle. Ainsi, les lithologies potentiellement rencontrées en base des fossés ont pu être classées en fonction du potentiel de développement de porosité et de perméabilité matricielle dans les cœurs de failles, les zones endommagées et le réseau pervasif de fractures dans le protolithe. L’évolution de la fracturation dans les zones de failles a également pu être appréhendé, et une méthodologie de modélisation double milieu a été élaborée pour caractériser la porosité et la perméabilité de fractures et modéliser le fonctionnement d’un doublet géothermique dans une faille synthéthique équivalente aux cibles des projets géothermiques / High temperature geothermal projects for electricity production are in France mostly localized in the basement of basins linked to the West European Rifting event. The basement of theses basins have been studied on two outcrop analogues at the shoulders of the rift: the Northern Vosges mountains for the Upper Rhine Graben and the Eastern border of the Massif central for the Valence Graben. This study has shown that the fault network is organized in three orders of size with characteristic length and spacing, and that form characteristic structural blocks. The orientation and spacing of these faults and the presence or absence of some size orders are the result of structural inheritance of the basement and the mechanism of the basin opening. The reservoir potential of the basement rocks and the surrounding sedimentary cover has been analysed in light of the fault zones structure and the weathered layer at the top of the basement. Thus, the basement rocks of the basins has been classified in light of the potential of matrix porosity and permeability development in the fault core, the damaged zone and the fractured protolith. The evolution of the fracture network in the fault zone has been studied too, with the development of a double-porosity model in order to characterize the fracture porosity and permeability, and therefore simulate the working of a geothermal doublet in a synthethic fault zone analogue of the geothermal drilling targets