La reproduction dans des mammifères est réglée par les neurones qui synthétisent et sécrètent l'hormone de gonadotropin-sortie (GnRH) et à travers l'espèce ces neurones sont présents dans peu de nombres dispersés dans l'hypothalamus. En raison de limité neurogenesis de ceux des types cellulaires neuronaux à l'extérieur du cerveau dans placode olfactif, ces neurones sont soumis au règlement serré pendant le développement embryonnaire pour atteindre leurs objectifs finaux dans l'hypothalamus, de la naissance jusqu'à la puberté pour la sécrétion minimale d'hormone et pendant des adultes pour réaliser la sécrétion pulsatile de l'hormone. La dérégulation dans n'importe lequel de ces mécanismes peut mener aux effets délétères sur la reproduction adulte et des pathologies cliniques comme l'absence de puberté, hypogonadism, la stérilité, l'aménorrhée, etc. Kallmann syndrome (KS), un d'entre ceux sévères (graves) reproducteur / Reproduction in mammals is regulated by neurons that synthesize and secrete gonadotropin-releasing hormone (GnRH) and across the species these neurons are present in few numbers scattered in the hypothalamus. Due to limited neurogenesis of these neuronal cell types outside the brain in the olfactory placode, these neurons are subjected to tight regulation during embryonic development to reach their final targets in the hypothalamus, from birth until puberty for minimal secretion of hormone and during adults to achieve pulsatile secretion of the hormone. Deregulation in any of these mechanisms may lead to deleterious effects on adult reproduction and clinical pathologies like absence of puberty, hypogonadism, sterility, amenorrhea, etc. Kallmann syndrome (KS), one of these severe reproductive pathologies is an inherited disorder and patients affected with this syndrome display anosmia (inability to smell) and hypogonadotropic hypogonadism (HH). Genetic screening of molecules in these patients lead to identification of genes like KAL1, FGFR1, FGF8, PROK2, PROKR2, WDR11 and CHD7 encoding proteins that play an important role in migration and targeting of olfactory system during embryonic development however these genes account only for 30% of KS cases emphasizing the need for further characterization and identification of other genes. While these proteins are involved in ontogenesis olfactory and GnRH system, genetic screening of molecules in patients suffering from normosmic idiopathic HH lead to identification of genes encoding for Kisspeptin receptor-GPR54, TAC-TACR3, LEP-LEPR, PCSK-1, GnRH receptor-GnRHR and GnRH-1 itself that play a crucial role in occurrence of puberty or adult reproduction. Here, for my PhD thesis, we focused on studying the role of guidance molecule Semaphorin3A (Sema3A)-Neuropilin1 (Nrp1) interactions in ontogenesis of GnRH neurons during embryonic development while in adults we first addressed the question if hypothalamic Kisspeptin neurons interact with neurons containing neuronal nitric oxide synthase (nNOS), the mutation of which causes HH in mice, and physiological significance of this interactions in regulation of GnRH neurons and neuroendocrine control of female reproduction. Finally our results demonstrate that Sema3A-Nrp1 interactions are implicated in ontogenesis of olfactory and GnRH neurons during embryonic development and nNOS neurons are important mediators of peripheral estrogens-kisspeptin signaling onto GnRH neurons and adult reproduction and propose to further study the implication of nNOS neurons in reproductive pathologies.

The growing need for better definition of flow units and depositional heterogeneities in petroleum reservoirs and aquifers has stimulated a renewed interest in outcrop studies as reservoir analogues in the last two decades. Despite this surge in interest, outcrop studies remain largely two-dimensional; a major limitation to direct application of outcrop knowledge to the three dimensional heterogeneous world of subsurface reservoirs. Behind-outcrop Ground Penetrating Radar (GPR) imaging provides high-resolution geophysical data, which when combined with two dimensional architectural outcrop observation, becomes a powerful interpretation tool. Due to the high resolution, non-destructive and non-invasive nature of the GPR signal, as well as its reflection-amplitude sensitivity to shaly lithologies, three-dimensional outcrop studies combining two dimensional architectural element data and behind-outcrop GPR imaging hold significant promise with the potential to revolutionize outcrop studies the way seismic imaging changed basin analysis. Earlier attempts at GPR imaging on ancient clastic deposits were fraught with difficulties resulting from inappropriate field techniques and subsequent poorly-informed data processing steps. This project documents advances in GPR field methodology, recommends appropriate data collection and processing procedures and validates the value of integrating outcrop-based architectural-element mapping with GPR imaging to obtain three dimensional architectural data from outcrops. Case studies from a variety of clastic deposits: Whirlpool Formation (Niagara Escarpment), Navajo Sandstone (Moab, Utah), Dunvegan Formation (Pink Mountain, British Columbia), Chinle Formation (Southern Utah) and St. Mary River Formation (Alberta) demonstrate the usefulness of this approach for better interpretation of outcrop scale ancient depositional processes and ultimately as a tool for refining existing facies models, as well as a predictive tool for subsurface reservoir modelling. While this approach is quite promising for detailed three-dimensional outcrop studies, it is not an all-purpose panacea; thick overburden, poor antenna-ground coupling in rough terrains typical of outcrops, low penetration and rapid signal attenuation in mudstone and diagenetic clay- rich deposits often limit the prospects of this novel technique.

The growing need for better definition of flow units and depositional heterogeneities in petroleum reservoirs and aquifers has stimulated a renewed interest in outcrop studies as reservoir analogues in the last two decades. Despite this surge in interest, outcrop studies remain largely two-dimensional; a major limitation to direct application of outcrop knowledge to the three dimensional heterogeneous world of subsurface reservoirs. Behind-outcrop Ground Penetrating Radar (GPR) imaging provides high-resolution geophysical data, which when combined with two dimensional architectural outcrop observation, becomes a powerful interpretation tool. Due to the high resolution, non-destructive and non-invasive nature of the GPR signal, as well as its reflection-amplitude sensitivity to shaly lithologies, three-dimensional outcrop studies combining two dimensional architectural element data and behind-outcrop GPR imaging hold significant promise with the potential to revolutionize outcrop studies the way seismic imaging changed basin analysis. Earlier attempts at GPR imaging on ancient clastic deposits were fraught with difficulties resulting from inappropriate field techniques and subsequent poorly-informed data processing steps. This project documents advances in GPR field methodology, recommends appropriate data collection and processing procedures and validates the value of integrating outcrop-based architectural-element mapping with GPR imaging to obtain three dimensional architectural data from outcrops. Case studies from a variety of clastic deposits: Whirlpool Formation (Niagara Escarpment), Navajo Sandstone (Moab, Utah), Dunvegan Formation (Pink Mountain, British Columbia), Chinle Formation (Southern Utah) and St. Mary River Formation (Alberta) demonstrate the usefulness of this approach for better interpretation of outcrop scale ancient depositional processes and ultimately as a tool for refining existing facies models, as well as a predictive tool for subsurface reservoir modelling. While this approach is quite promising for detailed three-dimensional outcrop studies, it is not an all-purpose panacea; thick overburden, poor antenna-ground coupling in rough terrains typical of outcrops, low penetration and rapid signal attenuation in mudstone and diagenetic clay- rich deposits often limit the prospects of this novel technique.

Rock glaciers are dynamic landforms and, as such, exhibit interesting and welldeveloped structural features, which translate to surface morphology in the form of ridges and furrows. These distinguishing features have led researchers to study the physics behind the movement and internal deformation of rock glaciers. For years researchers had no access to the internal makeup of rock glaciers. Thus, proposed models and discussion have been based on theoretical concepts of electromagnetic (EM) wave propogation. With the application of ground penetrating radar (GPR) to provide a view of the interior structure of a rock glacier, researchers had “real” data to verify their models. However, no comparison has been made between a GPR profile and an actual cross-section of a rock glacier. The purpose of this thesis is to validate the fidelity of GPR in showing the actual structure of a rock glacier. A trench that was excavated through the toe of a rock glacier on Mount Mestas in south central Colorado provided a view of the actual structure of the landform. The structure in the trench was compared with GPR and EM data. The GPR study was conducted using a PulsEKKOTM 100A subsurface imaging radar with 25, 50, and 100 MHz antennas, to detect dielectric contrasts within the rock glacier. A frequency domain EM34 by Geonics LtdTM was also used to supplement the GPR data by measuring the rock glacier’s conductivity at various depths. This thesis proved, by utilizing statistics, that GPR is a useful tool in visualizing the interior structure of rock glaciers. The 100 MHz antennas clearly show small scale reflection horizons caused by changes in clast orientation and subsurface material composition. These events coincide with structures seen in the trench. Individual clasts greater than 0.375 m were also recognized as point sources in the GPR profiles. Large continuous bedding layers were observed with the 25 and 50 MHz antennas, which reflect the structure seen in the trench. A large scale thrust fault was also located with the GPR. However, this was not visible in the panoramic photograph because the fault occurs below the base of the trench.

No description available.

Advances in geophysical and remote sensing technology, specifically with ground penetrating radar (GPR) and geographic information systems (GIS), have led to increased use for archaeological research within cemeteries. Because of its non-invasive manner and high resolution of subsurface anomalies, GPR is ideal for surveying areas with marked or unmarked graves within cemeteries. Using a GIS assists cemetery research by facilitating integration of datasets and projection of spatial data. What has not been attempted to this point is systematic attempting to correlate detection rates of marked graves using a GPR with the time frame of the grave while incorporating the data within a GIS. This research project is the first to correlate rates of detection with a GPR and the age of marked graves with the data integrated into a GIS platform. Greenwood Cemetery, located in downtown Orlando, FL, was chosen for the study. A total of 1738 graves (ranging in date from 1883-2008) were surveyed with a GPR and then paired with probe data to address whether there is a correlation between rates of detection and age of the surveyed grave. Further, the correlation between the rates of geophysical detection to an independent verification by a T-bar probe and the relationship between the depth and age of the grave by decade were examined. Finally, the problem of collating the relevant survey data was addressed by using a GIS for data integration. The results of the geophysical survey show a correlation between ages of graves and rates of detection. Older graves were detected less with a GPR compared to higher detection rates of more recent graves. The results also support the utility of pairing GPR with probe data for independent verification of findings but show no relationship between ages of grave and depth of burial. Finally, the integration of the survey data to a GIS helps to address the issue of data storage and management, the accuracy of the spatial data, and the ability of the data to be viewed and queried in meaningful ways.

No description available.

Neste trabalho foi realizado um levantamento GPR 4D em laboratório no qual foi simulado o vazamento de óleo de uma ETD - Estação de Transmissão e Distribuição de Energia Elétrica. Os estudos consistiram em derramar 15 litros de óleo em três experimentos: tanque contendo areia seca, tanque contendo areia úmida mais gradiente hidráulico e tanque contendo areia úmida. Em todos os experimentos o objetivo foi detectar a pluma de contaminação e avaliar a migração desse óleo com o tempo. Os dados GPR 4D foram adquiridos utilizando-se uma antena blindada de 400 MHz modelo SIR-3000 equipamento da GSSI. O monitoramento no tempo de aquisição dos dados variou de 2 minutos até 12 dias. No experimento com o tanque preenchido com areia seca não foi possível determinar a pluma de contaminação devido ao baixo contraste entre as propriedades físicas do meio e a pluma contaminante. No experimento em que o tanque foi preenchido com areia úmida e havia a presença de um gradiente hidráulico, foi possível determinar a migração da pluma de contaminação a partir do 5º dia. Para finalizar, o 3º experimento onde o tanque estava cheio de areia úmida também não foi possível identificar a pluma, devido ao baixo contraste entre as propriedades físicas. Nesta pesquisa também foram realizadas modelagens numéricas 2D utilizando o método FDTD, onde foram simulados os três experimentos, considerando posições intermediárias da pluma de contaminação em função do tempo. Os resultados das modelagens foram concordantes com os resultados obtidos com dados reais e ajudaram a definir o padrão de reflexão da pluma contaminante. Os promissores resultados indicam que a determinação efetiva da pluma contaminante de óleo numa ETD é possível desde o meio que esteja saturado com água. Portanto, para garantir o sucesso das pesquisas GPR para fins de mapeamento e delineamento de plumas de contaminação em ETDs recomenda-se que a aquisição dos dados seja feita após um período de chuvas. / In this work a 4D GPR survey was accomplished in a laboratory in which a oil leak from a ETD Estação de Transmissão e Distribuição of electric energy was simulated. The studies consisted in an oil spill (15 liters) in three different experiments: i) tank containing dry sand, ii) tank containing wet sand with a hydraulic gradient and iii) tank containing wet sand. In all experiments the objective was detect the contamination plume and evaluate the migration of the oil with the time. The 4D GPR data was acquired using a shielded antenna of 400 MHz model SIR-3000 of the GSSI equipment. The time monitoring of the data acquisition ranged from 2 minutes up to 12 days. In the experiment-1 with the tank filled with dry sand wasnt possible to determine the plume contamination due to the low contrast of the physical properties between the environment and the plume. In the experiment-2 where the tank filled with the dry sand in the presence of a hydraulic gradient, was possible to determine the migration of the plume from the fifth day. Finally, the experiment-3 where the tank was filled with wet sand wasnt possible to identify the plume, due to the low contrast between the physical properties. This research also conducted 2D numerical modeling using the FDTD method, where the three experiments were simulated, considering intermediary positions of the contamination plume with respect with time. The results of the modeling were consistent with the results obtained with real data and helped to define a pattern of reflection of the contamination plume. The promising results indicate that the effective determination of the contaminating plume of oil in an ETD is possible provided that the environment be saturated with water. Therefore, to guarantee the success of researches with GPR for mapping and delineation of contamination plumes in ETDs its recommended that the data acquisition be realized in the rainy season.

Concerns regarding the issue of climate change and, in particular, the rapid retreat of glaciers around the world, have placed great importance on glacial monitoring. Some of the methods most commonly used to observe glacial change--direct mass balance measurements and remote sensing--provide valuable information about glacier change. However, these methods do not address the englacial and subglacial environments. Surface meltwater that enters englacial and subglacial hydrological networks can contribute to acceleration of ice flow, increased calving on marine-terminating glaciers, surges or outburst floods, and greater overall ablation rates. Because subsurface drainage systems often freeze during the winter and re-form each summer, examining the seasonal evolution of these networks is crucial for assessing the impact that internal drainage may have on the behavior of a glacier each year. The goal of this study is to determine the role englacial and subglacial drainage system evolution plays in influencing summer ablation and discharge at the terminus of Exit Glacier, a small valley glacier located in South-central Alaska. During the summers of 2010 and 2011, we used ground-penetrating radar (GPR) to locate internal drainage features on the lower 100 meters of the glacier. GPR surveys were conducted in June and August of each year in an effort to observe the evolution of the drainage systems over the course of an ablation season. Three antenna frequencies--250, 500, and 800 MHz--were used on a dual frequency GPR so that various resolutions and depths in the ice could be viewed simultaneously. Stream monitoring was conducted to document discharge in the proglacial stream throughout the 2011 season. These data were compared with weather records to differentiate noticeable meltwater releases from precipitation events. Additionally, morphological changes in the glacier were observed through photographic documentation. Throughout the observation period, significant subglacial tunnels appeared, followed by the collapse of terminal ice above the tunnels. This phenomenon was most noticeable in 2011. These observations indicate that the internal drainage systems near the terminus of Exit Glacier became very well-developed each summer, and contributed approximately 75 meters of ice loss between June, 2010 and August, 2011.

This project addresses the topic of evaluating water movement inside a hillslope using a combination of conventional and advanced geophysical techniques. While slope dynamics have been widely studied, ground water movement in hills is still poorly understood. A combination of piezometers, ground-penetrating radar (GPR), and electrical resistivity (ER) surveys were used in an effort to monitor fluctuations in the subsurface water level in a reengineered slope near Keokuk, Iowa. This information, integrated with rainfall data, formed a picture of rainfall-groundwater response dynamics. There were two hypotheses: 1) that the depth and fluctuation of the water table could be accurately sensed using a combination of monitoring wells, ground-penetrating radar and resistivity surveys; and 2) that the integration of data from the instrumentation array and the geophysical surveys would enable the characterization of water movement in the slope in response to rainfall events. This project also sought to evaluate the utility and limitations of using these techniques in landslide and hydrology studies, advance our understanding of hillslope hydrology, and improve our capacity to better determine when slope failure may occur. Results from monitoring wells, stratigraphy, and resistivity surveys at the study site indicated the presence of a buried swale, channelizing subsurface storm flow and creating variations in groundwater. Although there was some success in defining hydrologic characteristics and response of the slope using this integrated approach, it was determined that GPR was ultimately not well suited to this site. However, the use of GPR as part of an integrated approach to study hillslope hydrology still appears to hold potential, and future work to further evaluate the applicability and potential of this approach would be warranted.