11 resultados para Subsurface drainage.


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Onshore, the Piacenzianof the Mondego and Lower Tagus Tertiary basins comprises siliciclastic sediments deposited in shallow marine to continental environments. The outcrops of the deposits are relatively widespread in the Aveiro and Seuibal region. A lithostratigraphic synthesis based on the correlation of geological sections, is presented for the two basins. In general, the Piacenzian sediments display a regressive sucession. The Late Tortonian-Zanclean (?) confined drainage pattern changed at the beginning of Piazencian, to fluvial systems draining to the Atlantic, and capturing the drainage of the inner parts of the Hesperic Meseta. The Piacenzian sedimentary sequence post-dates one of the uprising phases during Neogene compression, recorded by a strong regional unconformity. Some local active faulting - as in Lousa, Rio Maior and Senibal- Pinhal Novo - allowed the local thickening of the sedimentary record. Later compressive tectonism continues to generate reverse faulting and diapiric reactivation, affecting those sediments. Currently, the Piacenzian deposits culminates the marginal piedmonts, widely eroded by the Quaternary fluvial dissection.

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Cabatuquila conglomerate ferricrete (Malanje Province, located North Central Angola) corresponds to a thick (1O-15m) and hardcornice at the top of "Baixa de Cassanje" escarpment. "Baixa de Cassanje" is a large graben part of South Congo basin. Cabatuquila conglomerate ferricrete seems to correspond to a Plio-Pleistocene morphology which has already disappeared. Laterization dynamics and ferricrete formation processes took place on the Tertiary surface, before being tilted to the Congo Basin. Materials submitted to these processes are mainly alluvial deposits from a pre-Cuanza drainage system. This drainage system flowed to the North before being captured to the Atlantic, as a consequence of the movement which deformed the Tertiary surface during the Pleistocene. The erosion dynamics, which created the Cassanje depression, has occurred after the late Tertiary surface deformation. That dynamics might be related to the Cuango drainage system, which was reorganized after that deformation.

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Onshore, the Piacenzian of the Mondego and Lower Tagus Tertiary basins comprises siliciclastic sediments deposited in shallow marine to continental environments. The outcrops of the deposits are relatively widespread in the Aveiro and Setúbal region. A lithostratigraphic synthesis based on the correlation of geological sections, is presented for the two basins. In general, the Piacenzian sediments display a regressive sucession. The Late Tortonian-Zanclean (?) confined drainage pattern changed at the beginning of Piazencian, to fluvial systems draining to the Atlantic, and capturing the drainage of the inner parts of the Hesperic Meseta. The Piacenzian sedimentary sequence post-dates one of the uprising phases during Neogene compression, recorded by a strong regional unconformity. Some local active faulting - as in Lousa, Rio Maior and Senibal- Pinhal Novo - allowed the local thickening of the sedimentary record. Later compressive tectonism continues to generate reverse faulting and diapiric reactivation, affecting those sediments. Currently, the Piacenzian deposits culminates the marginal piedmonts, widely eroded by the Quaternary fluvial dissection.

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An Upper Miocene important sedimentary break can be accurately recognised in the Portuguese basins and is reflected by a drastic palaeogeographic change in relation to a large-scale tectonic event of probable uppermost Vallesian-Turolian (9,5 Ma; middle Tortonian) age. The characterisation of the sedimentary record of this tectonic event, as well as its relations with interpreted active faults is made for different situations: Douro (NW border), Mondego, Lower-Tagus and Sado Tertiary basins. The sedimentary record, considered upper Tortonian-Messinian ? (uppermost Vallesian-Turolian ?) is interpreted mainly as endorheic alluvial fans (internal drainage), developed along active NNE-SSW indent-linked strike-slip faults and NE-SW reverse faults. At NE Portugal, proximal fluvial systems of an endorheic hydrographic network drained eastwards to the Spanish Duero interior Basin. The main evidences of the betic compression clímax in Portugal mainland are presented; the interpreted active tectonic structures are in accordance with an intense NNW-SSE crustal shortening, but some regional differences are also documented.

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In the Longroiva-Vilariça area, the identification of Cenozoic lithostratigraphic units, the sedimentology and the characterization of its geometric relations with tectonic structures allowed the interpretation of the palaeogeographic main stages: 1) the greenwhitish Vilariça Arkoses (Middle Eocene to Oligocene ?) represent proximal sediments of a very low gradient drainage towards the eastern Spanish Tertiary Duero Basin; 2)Quintãs Formation (late Miocene ?) are brown-reddish coloured piedmont alluvial deposits, correlative of important vertical displacement (western tectonic block relative uplift) along the NNE-SSW indent-linked strike-slip Bragança-Vilariça-Longroiva fault zone, interpreted as a reactivated deep hercynian fracture, with left-lateral movement; 3) the red Sampaio Formation (Gelasian-early Pleistocene ?)was interpreted as downhill conglomeratic deposits related with important overtrusting along this fault zone (the definition of the present-day narrow graben configuration) and correlative of the atlantic hydrographic incision stage beginning; 4) conglomeratic terraces (middle and late Pleistocene ?); 5) alluvial plains and colluvial deposits (Holocene).

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This paper describes the palaeoweathering, cementation, clay minerals association and other closely related characteristics of central Portugal allostratigraphic Tertiary units (SLD's), that can be used for palaeoclimatic interpretation and palaeoenvironmental reconstruction. Lateral and vertical changes in palaeosols are of value for improving our understanding of the autocyclic and allocyclic controls on sediment acumulation in an alluvial basin, but they can also have stratigraphic importance. In some cases it is concluded that the geomorphological setting may have been more decisive than climatic conditions to the production of the palaeoweathering. During late Palaeogene (SLD7-8), surface and near-surface silicification were developed on tectonically stable land surfaces of minimal local relief under a semi-arid climate; groundwater flow was responsible for some eodiagenesis calcareous accumulations, with the neoformation of palygorskite. Conditions during the Miocene (SLD9-11) were favourable for the smectization of the metamorphic basement and arenization of granites. Intense rubefaction associated with basement conversion into clay (illite and kaolinite), is ascribed to internal drainage during late Messinian-Zanclean (SLD12). During Piacenzian (SLD13) intense kaolinization and hydromorphism are typical, reflecting a more humid and hot temperate climate and important Atlantic fluvial drainage. Later on (Gelasian-early Pleistocene ?; SLD14). more cold and dry conditicns are interpreted, at the beginning of the fluvial incision sage. Silica cementation is identified in the upper Eocence-Oligocene ? (SLD18; the major period of silicification), middle to upper Miocene (SLD10)and upper Tortonian-Messinian (SLD11); these occurrences are compatible with either arid or semi-arid conditions and the establishment of a flat landscape upon which a silcrete was developed.

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Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

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Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente, Perfil de Engenharia de Sistemas Ambientais

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Breast cancer is the most common type of cancer among women all over the world. An important issue that is not commonly addressed in breast cancer imaging literature is the importance of imaging the underarm region—where up to 80% of breast cancer cells can metastasise to. The first axillary lymph nodes to receive drainage from the primary tumour in the breast are called Sentinel Node. If cancer cells are found in the Sentinel Node, there is an increased risk of metastatic breast cancer which makes this evaluation crucial to decide what follow-up exams and therapy to follow. However, non-invasive detection of cancer cells in the lymph nodes is often inconclusive, leading to the surgical removal of too many nodes which causes adverse side-effects for patients. Microwave Imaging is one of the most promising non-invasive imaging modalities for breast cancer early screening and monitoring. This novel study tests the feasibility of imaging the axilla region by means of the simulation of an Ultra-Wideband Microwave Imaging system. Simulations of such system are completed in several 2D underarm models that mimic the axilla. Initial imaging results are obtained by means of processing the simulated backscattered signals by eliminating artefacts caused by the skin and beamforming the processed signals in order to time-align all the signals recorded at each antenna. In this dissertation several image formation algorithms are implemented and compared by visual inspection of the resulting images and through a range of performance metrics, such as Signal-to-Clutter Ratio and FullWidth Half Maximum calculations. The results in this study showed that Microwave Imaging is a promising technique that might allow to identify the presence and location of metastasised cancer cells in axillary lymph nodes, enabling the non-invasive evaluation of breast cancer staging.

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The focus of this Thesis was the study of the sensor domains of two heme-containing methyl-accepting chemotaxis proteins (MCP) from Geobacter sulfurreducens: GSU0582 and GSU0935. These domains contain one c-type heme, form swapped dimers with a PAS-like fold and are the first examples of a new class of heme sensors. NMR spectroscopy was used to assign the heme and polypeptide signals in both sensors, as a first step to probe conformational changes in the vicinity of the hemes. However, the presence of two conformations in solution impaired the confident assignment of the polypeptide signals. To understand how conformational changes and swapped dimerization mechanism can effectively modulate the function of the two sensor domains and their signal transduction process, the sensor domains folding and stability were studied by circular dichroism and UV-visible spectroscopy. The results showed differences in the thermodynamic stability of the sensors, with GSU0582 displaying higher structural stability. These studies also demonstrated that the heme moiety undergoes conformational changes matching those occurring at the global protein structure and that the content of intrinsically disordered segments within these proteins (25% for GSU0935; 13% for GSU0582) correlates with the stability differences observed. The thermodynamic and kinetic properties of the sensor domains were determined at different pH and ionic strength by visible spectroscopy and stopped-flow techniques. Despite the remarkably similar spectroscopic and structural features of the two sensor domains, the results showed that their properties are quite distinct. Sensor domain GSU0935 displayed more negative reduction potentials and smaller reduction rate constants, which were more affected by pH and ionic strength. The available structures were used to rationalize these differences. Overall, the results described in this Thesis indicate that the two G. sulfurreducens MCP sensor domains are designed to function in different working potential ranges, allowing this bacterium to trigger an adequate cellular response in distinct anoxic subsurface environments.

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Release of chloroethene compounds into the environment often results in groundwater contamination, which puts people at risk of exposure by drinking contaminated water. cDCE (cis-1,2-dichloroethene) accumulation on subsurface environments is a common environmental problem due to stagnation and partial degradation of other precursor chloroethene species. Polaromonas sp. strain JS666 apparently requires no exotic growth factors to be used as a bioaugmentation agent for aerobic cDCE degradation. Although being the only suitable microorganism found capable of such, further studies are needed for improving the intrinsic bioremediation rates and fully comprehend the metabolic processes involved. In order to do so, a metabolic model, iJS666, was reconstructed from genome annotation and available bibliographic data. FVA (Flux Variability Analysis) and FBA (Flux Balance Analysis) techniques were used to satisfactory validate the predictive capabilities of the iJS666 model. The iJS666 model was able to predict biomass growth for different previously tested conditions, allowed to design key experiments which should be done for further model improvement and, also, produced viable predictions for the use of biostimulant metabolites in the cDCE biodegradation.