Estudamos as propriedades eletrônicas, estruturais e hiperfinas, nos sítios de nitrogênio, para o composto imidazol nas fases gasosa e sólida. Utilizamos o método PAW que é um método ab initio all-electron, dentro da Teoria do Funcional da Densidade, através do código computacional CP-PAW. Nossos valores, tanto para a fase gasosa quanto para a fase cristalina do gradiente de campo elétrico no núcleo, de freqüência de acoplamento quadrupolar (ν) e parâmetro de assimetria (η) estão em ótima concordância com os resultados experimentais da literatura e são os primeiros resultados obtidos, por método ab initio no espaço recíproco, para os átomos de nitrogênio no imidazol cristalino. Utilizamos resultados da literatura e também aqui calculados para estudar a tendência de comportamento tanto de ν quanto de η para diferentes meros (um, dois, três, cadeia infinita) e cristal investigando, assim, a estreita influência das ligações de hidrogênio sobre os valores do Gradiente de Campo Elétrico nos núcleos de nitrogênio. / Here we study structural, electronic and hyperfine properties at the Nitrogen sites in imidazole in the gas and the crystal phases. We use the PAW method which is an ab initio all electron method in the framework of the Density Functional Theory, as embodied in the computer code CP-PAW. The results for quadrupole coupling (ν) and asymmetry parameter (η) at the gas and at the crystal phases are in excellent agreement with the experimental values in the literature. This is the first time that such calculations are performed for the crystalline imidazole through a reciprocal space approach. We also study the behavior of both ν and η trends studing diferent meres (one, two, three and infinite chain) and cristal to investigate the influence of hydrogen bonding on the Electric Field Gradient at the nucleus.

Two alternative technologies of communication inside a parallelized Conjugate-Gradient algorithm are presented and compared to the well known hypercubecommunication. The amount of communication is diskussed in detail. A large range of numerical results corroborate the theoretical investigations.

The Kribi-Campo sub-basin is the northernmost of a series of Aptian basins along the coast of West Africa. These extensional basins developed as a result of the northward progressive rifting of South America from West Africa, initiated c. 130 Ma ago. Post-rift sediments of the Kribi-Campo sub -basin contain several regional unconformities and changes in basin-fill architecture that record regional tectonic events. The tectono-stratigraphic evolution and plumbing system has been investigated using a high-quality 3D seismic reflection dataset acquired to image the deep-water Cretaceous-to-Present-day post-rift sediments. The study area is located c. 40 km offshore Cameroon in 600 to 2000 m present-day water depth, with full 3D seismic coverage of 1500 km2, extending down to 6.5 seconds Two-Way Travel time. In the late Cretaceous the basin developed as a result of tectonism related to movement of the Kribi Fracture Zone (KFZ), which reactivated in the late Albian and early Senonian. This led to inversion of the early syn-rift section overlying the KFZ to the southeast. Two main fault-sets - N30 and N120 - developed in the center and south of the basin. These normal faults propagated from the syn-rift sequences: the N120 faults die out in the early post-rift sequence (Albian time) whilst N30 faults tend to be associated with the development of a number of fault-related folds in the late Cretaceous post-rift sequence, and have a significant control on later deposition. The basin is filled by Upper Cretaceous to Recent sediments that onlap the margin. Seismic facies analysis and correlation to analogue sections suggest the fill is predominantly fine-grained sediments. The interval also contains discrete large scale channels and fans whose location and geometry were controlled by the KFZ and fault-related folds. These are interpreted to contain coarser clastics. Subsequently, during the Cenozoic, the basin experienced several tectonic events caused by reactivation of the KFZ. During the Cenozoic, deposition was characterized by Mass Transport Complexes (MTCs), polygonal faulting, channels, fans and fan-lobes, and aggradational gullies. The main sediment feeder systems were, at various times, from the east, southeast and northeast. The plumbing system shows the effects of an interplay of stratigraphic and structural elements that control fluid flow in the subsurface. Evidence for effective fluid migration includes the occurrence of widespread gas-hydrate-related Bottom Simulating Reflections (BSRs) 104 - 250 m below the seabed (covering an area of c. 350 km2, in water depths of 940 m - 1750 m), pipes and pockmarks. Focused fluid flow pathways have been mapped and observed to root from two fan-lobe systems in the Mid-Miocene and Pliocene stratigraphic intervals. They terminate near, or on, the modern seafloor. It is interpreted that overpressure occurred following hydrocarbon generation, either sourced from biogenic degradation of shallow organic rich mudstone, or from effective migration from a thermally mature source rock at depth. This latter supports the possibility also of hydrocarbon charged reservoirs at depth. Theoretical thermal and pressure conditions for gas hydrate stability provide an opportunity to estimate the shallow geothermal gradient. Variations in the BSR indicate an active plumbing system and local thermal gradient anomalies are detected within gullies and along vertically stacked channels or pipes. The shallow subsurface thermal gradient is calculated to be 0.052 oC m-1. With future drilling planned in the basin, this study also documents potential drilling hazards in the form of shallow gas and possible remobilised sands linked with interconnected and steeply dipping sand bodies.

Klimatologie vertikálního teplotního gradientu ve spodní a střední troposféře Climatology of temperature lapse rate in the lower and middle troposphere Abstract The main objective of this thesis is synoptic-climatological analysis of the temperature lapse rate (γ) in the lower and middle troposphere above the boundary layer at mid-latitudes of the northern hemisphere. The main part of the background research summarizes current knowledge about the mechanism of air temperature change with altitude, the effect of water vapour on γ, and stability conditions in the atmosphere. Radiation and net radiation are discussed to be one of the key factors influencing the behaviour of γ. The following chapter is summarizing findings about temporal and spatial variability of γ. The analysis of γ calculated from 850 and 300 hPa radiosounding data from Praha-Libuš is the core of this thesis. Results were used to describe annual variation of γ. Daily variation was not observed at this altitude. Further, the relationship of γ with air flow direction and Hess-Brezowsky synoptic types was analysed. The results show that the air flow direction and the synoptic situations together with the radiation and the humidity of atmosphere influence the value of γ. Based on the analogous analysis of γ in Poprad-Gánovce were results from...

De plus en plus d’études soulignent l’importance de la localisation intracellulaire des voies de signalisation. Nous avons développé des méthodes permettant de perturber cette localisation à l’aide de nanoparticules magnétiques. Ces dernières sont fonctionnalisées avec les protéines d’intérêts et deviennent ainsi un vecteur permettant de contrôler la localisation de la signalisation. Nous avons tout d’abord appliqué cette méthode dans un système modèle, des gouttes d’extrait cellulaire de Xénope, dans lesquelles nous avons créé artificiellement un gradient de protéines de signalisation à l’aide de nanoparticules magnétiques. Nous avons mis en évidence l’influence d’une asymétrie biochimique sur la localisation d’asters de microtubules. Dans un deuxième temps nous avons examiné la possibilité d’appliquer cette méthode dans des cellules HeLa adhérentes, pour perturber la localisation d’endosomes de signalisation rendus magnétiques. Nous avons cherché à optimiser les conditions expérimentales nécessaires pour contrôler la position d’endosomes de signalisation magnétiques Enfin, un troisième projet dont les résultats préliminaires sont présentés dans cette thèse, a consisté à utiliser un actuateur, non plus magnétique, mais biologique pour confiner une cascade de signalisation. Plus précisément la contraction d’un réseau d’actine confiné dans des gouttes d’extrait cellulaire est utilisée pour localiser des protéines de signalisation. Ces résultats démontrent l’intérêt de nanoparticules magnétiques pour induire et étudier des phénomènes de brisures de symétries dans des environnements biologiques / An increasing number of studies highlight the importance of signaling localization. We developed methods to perturb this localization using magnetic nanoparticles. Proteins of interest are grafted on magnetic nanoparticles, allowing to magnetically localize them. We first propose a new method to engineer directly a spatial gradient of signaling protein concentration within in cell extract droplets using super-paramagnetic nanoparticles. We observed a link between a spatial asymmetry in biochemical cues and microtubules aster positional information. Our assay provides a bottom-up approach to examine the minimum ingredients generating polarization and symmetry breaking within cells. We then examined the possibility to magnetically perturb endosomes position in HeLa cell. We found the experimental conditions to achieve this goal. Finally, we used directly cytoskeleton elements as actin filament to trigger asymmetrically confined signaling proteins and trigger microtubule assembly, in cell extract droplets. More generally, these results show how symmetry breaking within cells can be induced and studied using magnetic nanoparticles and biophysical tools.

Seepage direction is crucial for understanding the critical state and development of piping erosion. A stress-controlled apparatus was designed to investigate the piping behavior of cohesionless soil under upward flow condition. The components of the new apparatus included a loading chamber, a vertical and confining loading system, an upstream water supply device, a soil-water separating system, and a water collecting system. The loading chamber provides space for a soil specimen setting and loading. The combination of a vertical and a confining loading system was designed to apply complex stresses to a soil specimen. Under the stresses, the specimen was then eroded by the gradually increasing hydraulic head supplied by the water supply system. The eroded particle and spilling water were collected and detected by the soil-water separating system and the water collecting system. A series of experiments were carried out using the new apparatus. Results demonstrated the repeatability experiments and usefulness of the apparatus. The new apparatus allowed us to investigate the piping behavior under different stress states and hydraulic gradients. With this new apparatus and experiments, we found that lower and high critical hydraulic gradients (CHGs) should be included as the criteria of piping development based on the relationship between the hydraulic gradient and the seepage response. In addition, the stress state on the CHG and the particle erosion rate played important roles in the piping development. The outer pressure on the specimen can retard the development of erosion. In contrast, the hydraulic gradient was found to be positively correlated to the erosion rate. Results also indicated that a specimen would collapse once the amount of eroded small particles exceeds the critical value of 46.5 % of the soil.

The compact linear collider (CLIC) is a leading candidate for the next generation high energy linear collider. As any breakdown would result in a partial or full loss of luminosity for the pulse in which it occurs, obtaining a low breakdown rate in CLIC accelerating structures is a critical requirement for the successful operation of the proposed collider. This thesis presents investigations into the breakdown phenomenon primarily in the low breakdown rate regime of interest to CLIC, performed using the CERN DC spark systems between 2011 and 2014.The design, construction and commissioning of several new pieces of hardware, as well as the development of improved techniques to measuring the inter-electrode gap distance are detailed. These hardware improvements were fundamental in enabling the exciting new experiments mentioned below, which in turn have provided significant additional insight into the phenomenon of breakdown. Experiments were performed o measure fundamental parameters of individual breakdowns, including, the turn-on time and the delay before breakdown in order to gain an improved understanding of how breakdowns are triggered and the underlying process behind them. The turn-on time measurements are the highest bandwidth measurements made to date with the CERN DC systems and are closer than ever before to the value which is expected from the present understanding of breakdown simulations. Another key measurement was that of the breakdown rate scaling with electric field. Previous investigations of this relationship in the DC systems were unable to investigate breakdown rates below 10^3 breakdowns per pulse. These new results are able to investigate this relationship down to a breakdown rate of 10^-8 and are hence a considerable improvement. Thanks to these improved results a remarkable similarity to the scaling of the breakdown rate with electric field in RF cavities was discovered. The conditioning, or change in breakdown rate over time was also studied for the first time in the CERN DC spark systems as well as the newly built fixed gap system. The qualitative conditioning behaviour of the Fixed Gap System again showed interesting similarities to that observed in RF structures. Preliminary studies into the effect of pulse length and magnetic field on the breakdown rate were conducted as well. This is the first time the effect of a DC magnetic field was studied in a DC spark system and in contrast to experiments in RF cavities no statistically significant effect was observed. The dependence of the breakdown rate on pulse length, again the first measurement of its kind in a DC system also revealed a similar scaling law to that observed in RF accelerating structures. Both of these preliminary measurements would need to be repeated to confirm the results.

Internal instability of a widely graded cohesionless soil refers to a phenomenon in which its finer particles migrate within the void network of its coarser particles, as a result of seepage flow. Onset of internal instability of a soil is governed by a combination of geometric and hydromechanical constraints. Much concern exists for embankment dams and levees built using soils with a potential for internal instability. Migration of finer particles to a boundary where they can exit, by washing out, may cause erosion or piping failure and, occasionally, induce collapse of these soil structures. There is a need, in professional practice, to better understand the phenomenon and to develop improved methods to evaluate the susceptibility of a soil. A series of permeameter tests was performed on six widely-graded cohesionless materials. The objectives are to assess the geometric indices proposed for evaluation of susceptibility, and examine hydromechanical factors influence the onset of internal instability. A modified slurry mixing technique, with discrete deposition, was found satisfactory for reconstitution of the homogeneous saturated test specimens. The onset of internal instability was founded to be triggered by a combination of effective stress and hydraulic gradient. The finding yields a hydromechanical envelope, unique for a particular gradation shape, at which internal instability initiated. Three commonly used geometric criteria were comprehensively evaluated with reference to these experimental data and also a database compiled from the literature. The relative conservatism of each criterion was examined and a modified semi-empirical geometric rule then proposed based on the capillary tube model. A theoretical framework for plotting the hydromechanical envelope was established based on an extension of the α concept of Skempton and Brogan, and subsequently verified by test data. Finally, a novel unified approach was proposed to assess the onset of internal instability, based on combining geometric and hydromechanical indices of a soil. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The dichotomy of contrastive and allophonic phonological relationships has a long-standing tradition in phonology, but there is a growing body of research (see Hall, 2013, for a review) that points to phonological relationships that fall between contrastive and allophonic. The criteria most commonly used to define phonological relationships or resolve cases of ambiguous phonological relationships – namely (a) predictability of distribution, and (b) lexical distinction – are not always able to account for observed sound patterns. The main goal of this dissertation is to identify and apply quantitative measures (relative frequency and minimal pair counts) to the traditional criteria in order to better account for cases of intermediate phonological relationships or, in other words, to account for different strengths and degrees of contrast. Twenty native speakers of Laurentian French (LF) participated in Experiment 1, an AX discrimination task, and Experiment 2, a four-interval AX (4IAX) task, which tested the broader relationships of allophony and contrast. It was hypothesized, based on previous experiments (Boomershine et al., 2008; Dupoux et al., 1997; Ettlinger & Johnson, 2009; Johnson & Babel, 2010; Kazanina et al., 2006; Peperkamp et al., 2003; Pruitt et al., 2006), that phones in an allophonic relationship would be more difficult to perceive than phones in a contrastive relationship. Results confirmed previous findings, with longer reaction times for allophonic pairs as compared to contrastive pairs in the AX task (p<.001), as well as in the 4IAX task (p = .004). For Experiments 3, 4 and 5, thirty native speakers of LF participated in an AX, a 4IAX and a similarity rating task. Measures of functional load, frequency and acoustic similarity were applied to pairs of phones in allophonic and phonemic relationships in order to quantify the degree of contrast between pairs. If a gradient view of contrast was supported, it was hypothesized that High Contrast vowels [a-ɔ] would yield higher accuracy, faster reaction times and lower similarity ratings; Low Contrast vowels [y-ʏ] would yield lower accuracy, slower reaction times and higher similarity ratings; and Mid Contrast vowels [o-ʊ] would yield results that fell between the two extremes. If, on the other hand, a strict binary interpretation of contrast was supported, High Contrast vowels and Mid Contrast vowels should yield similar results since these vowels are considered to be in a phonemic relationship, with higher accuracy, faster reaction times and lower similarity ratings, while Low Contrast vowels [y-ʏ], in an allophonic relationship, should yield lower accuracy, slower reaction times and higher similarity ratings. The results from Experiments 3 (AX) and 4 (4IAX) show that the High Contrast pairs yielded significantly higher accuracy scores and faster reaction times than both Mid and Low Contrast pairs (Experiment 3: p<.001 for both High vs. Mid and High vs. Low comparisons; Experiment 4: p = .039 for High vs. Mid, p = .055 for High vs. Low comparisons). However, no significant differences were found between Mid and Low Contrast pairs in these two experiments. The results from Experiment 5 matched gradient predictions, showing significant differences between High, Mid and Low conditions, with similarity being judged highest for Low pairs, lowest for High pairs, and ratings for Mid pairs falling exactly between the other two levels (p<.001 for all comparisons). While results do not perfectly match gradient predictions, the findings provide evidence counter to a strict binary interpretation of contrast since traditionally phonemic pairs (High [a-ɔ] and Mid [o-ʊ]) were significantly different from one another in all experiments. The lack of difference between Mid and Low Contrast pairs could be due to the measures of functional load and frequency for Mid pairs being closer to those of Low pairs, and thus did not reflect a level of contrast that was equidistant between High and Low Contrast. Nevertheless, taken together with the results from Experiment 5, the results appear to support a gradient view of phonological relationships rather than a strictly dichotomous view. Quantitative measures therefore show promise in accounting for cases of intermediate phonological relationships.

This thesis proposes and tests an individually customizable model of the human crystalline lens. This model will be crucial in developing both research on the human eye and driving diagnostic tools to help plan and treat optical issues, such as those requiring refractive surgery. This thesis attempts to meet two goals: first, it will determine whether this new lens model can reproduce the major aberrations of real human eyes using a computational framework. Second, it will use clinical information to measure how well this model is able to predict post-operation results in refractive surgery, attempting to meet clinical standards of error. The model of the crystalline lens proposed within this thesis is shown to be valid, as it is able to both reproduce individual patient's optical information, and correctly predicts the optical results of a refractive surgery of an individual human eye within clinical standards of error.