Dispersal influences several ecological and evolutionary processes, such as intraspecific competition, genetic drift and inbreeding. It can lead to phenotypic mismatch with the habitat when a locally adapted individual winds up in an environment with a divergent selection regime compared to the source habitat. The aim of this project was to compare dispersive traits in the freshwater isopod Asellus aquaticus from a cave habitat, with surface dwelling isopods collected upstream and downstream from the cave system. The subterranean stream (cave) represents a rare, geographically limited habitat which has a divergent selective pressure compared to the surrounding habitats. Experiments on dispersal were performed in the laboratory, in darkness with IR-equipment for visualization. Displacement was measured using one-dimensional test arenas. Compared to the surface phenotype, the cave phenotype was expected to have reduced fitness outside of the cave and unlikely to successfully disperse to new areas of similar suitable conditions. The results did not follow my main hypothesis that isopods from the cave would be less dispersive than individuals from the surface. The inconclusive results might derive from large variation in the data and divergent adaptations which yield similar expression of dispersal.

This thesis presents the results of a study of the mechanisms responsible for limiting the laser pulse duration obtainable in xenon chloride lasers which are excited by UV-preionized, self-sustained gas discharges. The xenon chloride laser system, the principal emission band of which is centred around 308 nm, belongs to the class of high pressure gas lasers known as 'rare-gas halides'(RGH). RGH lasers are now well known for their high peak power output at a number of wavelengths from 193 nm to 353 nm in the ultraviolet region of the spectrum. To date, however, they have only been operated in the pulsed mode with laser pulse durations of ^~1000 ns for devices employing electron beam excitation and ^~30 ns for devices employing transverse discharge excitation. There is no a priori kinetic limitation which prevents RGH lasers from operating in the CW mode, and an attempt to extend the duration of the laser pulse would enable the quality of laser output to be improved. The laser pulse duration of a discharge excited XeCl^* laser was extended by about one order of magnitude - to 270 ns FWHM - by the use of a distributed resistance electrode to stabilize the discharge. The typical gas mixture used in the laser was ~2 atm of Ne (buffer gas), ~25 mbar of Xe, and 2.5 mbar of HC1. However, the laser pulse duration obtained was considerably shorter than the 500 ns duration, 2000 A peak current, discharge excitation pulse. The cause of this difference between the duration of the laser output pulse and the discharge current pulse was found by carrying out a comprehensive parametric study of the laser, combined with a detailed spectroscopic analysis and the results of a semi-empirical computer model. Two interrelated factors were identified as being responsible for the short duration of the laser output: namely, a temporal collapse of the discharge volume and a spatially non-uniform depletion of the HCl within this volume. The experimental results presented here contradict an earlier theory which ascribed the onset of discharge instabilities in RGH lasers to step-wise ionization of the minority rare gas atoms, and which attributed stability enhancement properties to the electronegative halogen gases used in RGH lasers.

近年來，許多專家學者廣泛探討偵測稀有疾病的發生率或稱為叢集上的空間或空間對時間的統計方法及模型。這些方法大部分都是處理個別資料或是只能偵測接近圓形的叢集。在這篇論文中，根據Choynowski在1959年所探討的方法，我們進一步提出針對整體資料去偵測非圓形叢集的方法，並且會將此方法與Nagarwalla’s Spatial Scan Statistic做比較。同時，我們會呈現模擬結果中的型一、型二誤差來衡量此方法的可行性。另外，我們也會將此方法實際應用到台灣的癌症死亡資料做探討。 / In recent years, many statistical methods have been proposed for detecting excesses of rare diseases, i.e., clusters, in space or in space-time. Most of these methods deal with case-event or individual-level data and can only detect clusters with shape close to circles. In this study, adapting Choynowski's (1959) idea, a simulation-based approach is proposed to detect non-circular clusters with aggregate or group-level data. The proposed cluster detection method will be used to compare with a frequently used method: Nagarwalla’s Spatial Scan Statistic. Computer simulation is used to illustrate the validity, with respect to Type-I and Type-II errors, of the proposed approach. In addition, the cancer mortality data in Taiwan area are also used as a demonstration of the proposed test.

Cette thèse s'insère dans un projet de caractérisation de verres et de vitrocéramiques fluorés dopés par des ions de terre rare. L'intérêt de tels matériaux et de pouvoir réaliser des systèmes ultra transparents avec de faibles pertes et également avec des fréquences de phonon faibles évitant les processus habituels qui limitent le rendement d'émission laser. L'étude s'articule sur deux aspects : spectroscopie expérimentale et modélisation. Les mesures en spectroscopie d'émission avec sélection de site offrent la possibilité de sonder le milieu autour des ions luminescents. Des mesures de déclin de luminescence sont un complément pour bien caractériser l'influence du milieu sur les ions luminescents. La connaissance des propriétés spectroscopiques de ces ions est fondamentale pour savoir comment avoir de bons rendements d'émission et des largeurs et formes de bandes adéquates pour les applications. L'environnement de la terre rare dans le verre de départ et dans la vitrocéramique est étudié par dynamique moléculaire, suivies de la simulation des spectres de luminescence, L'originalité de la méthode employée est d'introduire dans la structure des ions luminescents, d'en déterminer l'environnement et de calculer à partir de cet environnement le champ cristallin éprouvé par l'ion luminescent et de remonter à sa spectroscopie.

The solubility of the noble gases is temperature dependent. Other factors influencing solubility are the system pressure, the solute content of the water, and gravitational potentials. Most of the noble gases dissolved in ground water are from chemical equilibrium with the atmosphere. This equilibrium takes place in the recharge zone of the aquifer, typically in the soil. The final noble-gas concentrations are determined by the temperature, the elevation, the alteration of soil-gas composition by organisms, and soil-temperature gradients (which are in part a result of water-table depth and recharge rates). If the effects of temperature can be separated from the other influences, and if the noble-gas concentrations are not altered after recharge water enters the saturated zone, variations in recharge temperature with time may be determined by measuring the noble gases in dated ground-water samples. However, analysis of available data indicates that noble-gas concentrations frequently change after recharge. This change is usually the result of reequilibration with a biogenicgas phase produced within the aquifer, or from contact with air. In order to extend the calculation of recharge history to samples with complex histories of gas equilibrium a general equation for two stage equilibrium was derived. The variables in this equation are the initial temperature and pressure of equilibrium, the final temperature and pressure of equilibrium, and the molar water-to-gas ratio at the second equilibration. An equation of this type is constructed for each of the gases: neon, argon, krypton and xenon. These equations are solved simultaneously for four of the variables listed above while the value of one is assumed. Graphical techniques for determining which assumptions to use are presented. Ground-water samples were collected in glass tubes and analyzed by gas chromatograph-mass spectrometer, using double isotope dilution standardization. The analytical method is still developmental. Field sampling was undertaken in two locations, the Milk River aquifer of southern Alberta, Canada, and the Carrizo sand aquifer in southern Texas, in order to test the method. The preliminary data obtained may show correlation with known Holocene-Pleistocene climatic fluctuations, encouraging further development of the analytical technique and field research. Finally, a method for interpreting the climatic implications of oxygen and hydrogen isotope information from ground water in conjunction with noble-gas data is given.

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This dissertation focuses on two areas of garnet porphyroblast crystallization that have until now remained largely uninvestigated: epitaxial nucleation of garnet porphyroblasts and yttrium and rare earth (Y+REE) uptake in metamorphic garnet. The mechanism of epitaxial nucleation is explored as a step towards determining which aspects of interfaces are significant to interfacial energies and nucleation rates. Garnet from the aureole of the Vedrette di Ries tonalite, Eastern Alps, shows a clear case of epitaxial nucleation in which garnet nucleated on biotite with (110)grt || (001)bt with [100]grt || [100]bt. The occurrence is remarkable for the clear genetic relationships revealed by the microstructures and for its preservation of the mica substrate, which allows unambiguous determination of the coincident lattice planes and directions involved in the epitaxy. Not all epitaxial nucleation is conspicuous; to increase the ability to document epitaxial relationships between garnet and micas, I develop and apply a method for determining whether evidence for epitaxial nucleation of garnet is present in porphyroblasts containing an included fabric. Although the magnitude of uncertainties in orientation measurements for garnets from Passo del Sole (Switzerland), the Nevado Filabride Complex (Spain), and Harpswell Neck (USA) preclude definitive identification of epitaxial relationships, the method has potential to become a viable technique for creating an inventory of instances and orientations of epitaxial nucleation with appropriate sample selection. Using lattice-dynamics simulations, I explore the most commonly documented epitaxial relationship, (110)grt || (001)ms. The range of interfacial energies resulting from variations in the intracrystalline layer within garnet at the interface, the initial atomic arrangement at the interface, and the rotational orientation of the garnet structure relative to the muscovite structure shows that the intracrystalline layer within garnet has the greatest effect on interfacial energy. A complete understanding of the role of intergranular diffusion for yttrium and rare-earth-element uptake in porphyroblastic garnet is critical because the complexities of Y+REE zoning in garnets and the mechanisms of Y+REE uptake have implications for petrologic interpretations and garnet-based geochronology. Y+REE distributions in garnets from the Picuris Mountains (USA), Passo del Sole (USA), and the Franciscan Complex (USA) imply diverse origins linked to differing degrees of mobility of these elements through the intergranular medium during garnet growth.

This dissertation focuses on two areas of garnet porphyroblast crystallization that have until now remained largely uninvestigated: epitaxial nucleation of garnet porphyroblasts and yttrium and rare earth (Y+REE) uptake in metamorphic garnet. The mechanism of epitaxial nucleation is explored as a step towards determining which aspects of interfaces are significant to interfacial energies and nucleation rates. Garnet from the aureole of the Vedrette di Ries tonalite, Eastern Alps, shows a clear case of epitaxial nucleation in which garnet nucleated on biotite with (110)grt || (001)bt with [100]grt || [100]bt. The occurrence is remarkable for the clear genetic relationships revealed by the microstructures and for its preservation of the mica substrate, which allows unambiguous determination of the coincident lattice planes and directions involved in the epitaxy. Not all epitaxial nucleation is conspicuous; to increase the ability to document epitaxial relationships between garnet and micas, I develop and apply a method for determining whether evidence for epitaxial nucleation of garnet is present in porphyroblasts containing an included fabric. Although the magnitude of uncertainties in orientation measurements for garnets from Passo del Sole (Switzerland), the Nevado Filabride Complex (Spain), and Harpswell Neck (USA) preclude definitive identification of epitaxial relationships, the method has potential to become a viable technique for creating an inventory of instances and orientations of epitaxial nucleation with appropriate sample selection. Using lattice-dynamics simulations, I explore the most commonly documented epitaxial relationship, (110)grt || (001)ms. The range of interfacial energies resulting from variations in the intracrystalline layer within garnet at the interface, the initial atomic arrangement at the interface, and the rotational orientation of the garnet structure relative to the muscovite structure shows that the intracrystalline layer within garnet has the greatest effect on interfacial energy. A complete understanding of the role of intergranular diffusion for yttrium and rare-earth-element uptake in porphyroblastic garnet is critical because the complexities of Y+REE zoning in garnets and the mechanisms of Y+REE uptake have implications for petrologic interpretations and garnet-based geochronology. Y+REE distributions in garnets from the Picuris Mountains (USA), Passo del Sole (USA), and the Franciscan Complex (USA) imply diverse origins linked to differing degrees of mobility of these elements through the intergranular medium during garnet growth.