803 resultados para Meso
Resumo:
This thesis presents and discusses the results of ambient seismic noise correlation for two different environments: intraplate and Mid-Atlantic Ridge. The coda wave interferometry method has also been tested for the intraplate data. Ambient noise correlation is a method that allows to retrieve the structural response between two receivers from ambient noise records, as if one of the station was a virtual source. It has been largely used in seismology to image the subsurface and to monitor structural changes associated mostly with volcanic eruptions and large earthquakes. In the intraplate study, we were able to detect localized structural changes related to a small earthquake swarm, which main event is mR 3.7, North-East of Brazil. We also showed that the 1-bit normalization and spectral whitening result on the loss of waveform details and that the phase auto-correlation, which is amplitude unbiased, seems to be more sensitive and robust for our analysis of a small earthquake swarm. The analysis of 6 months of data using cross-correlations detect clear medium changes soon after the main event while the auto-correlations detect changes essentially after 1 month. It could be explained by fluid pressure redistribution which can be initiated by hydromechanical changes and opened path ways to shallower depth levels due to later occurring earthquakes. In the Mid-Atlantic Ridge study, we investigate structural changes associated with a mb 4.9 earthquake in the region of the Saint Paul transform fault. The data have been recorded by a single broadband seismic station located at less than 200 km from the Mid-Atlantic ridge. The results of the phase auto-correlation for a 5-month period, show a strong co-seismic medium change followed by a relatively fast post-seismic recovery. This medium change is likely related to the damages caused by the earthquake’s ground shaking. The healing process (filling of the new cracks) that lasted 60 days can be decomposed in two phases, a fast recovery (70% in ~30 days) in the early post-seismic stage and a relatively slow recovery later (30% in ~30 days). In the coda wave interferometry study, we monitor temporal changes of the subsurface caused by the small intraplate earthquake swarm mentioned previously. The method was first validated with synthetics data. We were able to detect a change of 2.5% in the source position and a 15% decrease of the scatterers’ amount. Then, from the real data, we observed a rapid decorrelation of the seismic coda after the mR 3.7 seismic event. This indicates a rapid change of the subsurface in the fault’s region induced by the earthquake.
Resumo:
Objectifs : le principal objectif de notre projet doctoral consiste à mettre en relief les transformations qui ont marqué le développement de l’oncologie et de la lutte contre le cancer au Québec au 20e siècle. Pour ce faire, nous nous sommes penchées sur trois niveaux d’analyse : 1) le niveau micro aborde l’organisation des services médicaux au sein d’une organisation hospitalière, soit l’Hôtel-Dieu de Québec. 2) Le niveau méso analyse une lutte professionnelle, soit la lutte entre les hématologues et les oncologues médicaux pour la reconnaissance de l’oncologie médicale. 3) Le niveau macro s’intéresse à l’organisation de la lutte contre le cancer à travers la province de Québec et aux différents modèles organisationnels créés. Principale hypothèse : l’émergence et la transformation de l’oncologie et de la lutte contre le cancer ont été influencées des rapports de collaboration et de compétition entre les acteurs impliqués en oncologie. En effet, il apparaît que ce champ se trouve en tension entre l’obligation de collaborer pour offrir des services de qualité aux patients et les dynamiques professionnelles et/ou organisationnelles. Cadre théorique : un cadre théorique a été développé pour chacun des niveaux d’analyse. Le niveau micro s’inspire des travaux de Frickel, Abbott et Strauss et s’intéresse plus particulièrement aux négociations entourant l’ordre social au sein d’un hôpital universitaire; le niveau méso emploie les travaux de Bourdieu et Abbott pour analyser la lutte entre deux spécialités médicales pour le contrôle des agents de chimiothérapie; et le niveau macro, de la sociologie des organisations et de la théorie néo-institutionnaliste pour mettre en relief l’émergence et la transformation de la lutte contre le cancer au Québec au 20e siècle. Méthodologie : l’approche de l’étude de cas a été adoptée et chaque niveau d’analyse constitue une étude de cas à part entière. Le corpus de données se compose de données archivistiques recueillies dans 10 centres d’archives canadiens, et de données d’entrevues. Une soixantaine d’entrevues avec des oncologues, des professionnels de la santé, des gestionnaires, des chercheurs et des fonctionnaires ont été réalisées. Conclusion : les différents niveaux d’analyse offrent différentes contributions qui leurs sont propres, mais l’ensemble de la thèse tend à mettre en relief la complexité du changement organisationnel à travers un perpétuel processus de définition et de redéfinition des frontières professionnelles et des organisations en raison du développement des connaissances scientifiques, des technologies, des expertises professionnelles et de l’environnement social, politique et économique.
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Significant advances in understanding the fundamental photophysical behavior of single-walled carbon nanotubes (SWNTs) have been made possible by the development of ionic, conjugated aryleneethynylene polymers that helically wrap SWNTs with well-defined morphology. My contribution to this work was the design and synthesis of porphyrin-containing polymers and the photophysical investigation of the corresponding polymer-wrapped SWNTs. For these new constructs, the polymer acts as more than just a solubilization scaffold; such assemblies can provide benchmark data for evaluating spectroscopic signatures of energy and charge transfer events and lay the groundwork for further, rational development of polymers with precisely tuned redox properties and electronic coupling with the underlying SWNT. The first design to incorporate a zinc porphyrin into the polymer backbone, PNES-PZn, suffered from severe aggregation in solution and was redesigned to produce the porphyrin-containing polymer S-PBN-PZn. This polymer was utilized to helically wrap chirality-enriched (6,5) SWNTs, which resulted in significant quenching of the porphyrin-based fluorescence. Time-resolved spectroscopy revealed a simultaneous rise and decay of the porphyrin radical cation and SWNT electron polaron spectroscopic signatures indicative of photoinduced electron transfer. A new polymer, S-PBN(b)-Ph2PZn3, was then synthesized which incorporated a meso-ethyne linked zinc porphyrin trimer. By changing the absorption profile and electrochemical redox potentials of the polymer, the photophysical behavior of the corresponding polymer-wrapped (6,5)-SWNTs was dramatically changed, and the polymer-wrapped SWNTs no longer showed evidence for photoinduced electron transfer.
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BACKGROUND: To explore the activity of dasatinib alone and in combination with gemcitabine and docetaxel in uterine leiomyosarcoma (uLMS) cell lines, and determine if dasatinib inhibits the SRC pathway. METHODS: SK-UT-1 and SK-UT-1B uLMS cells were treated with gemcitabine, docetaxel and dasatinib individually and in combination. SRC and paxcillin protein expression were determined pre- and post-dasatinib treatment using Meso Scale Discovery (MSD) multi-array immunogenicity assay. Dose-response curves were constructed and the coefficient of drug interaction (CDI) and combination index (CI) for drug interaction calculated. RESULTS: Activated phosphorylated levels of SRC and paxillin were decreased after treatment with dasatinib in both cell lines (p < 0.001). The addition of a minimally active concentration of dasatinib (IC25) decreased the IC50 of each cytotoxic agent by 2-4 fold. The combination of gemcitabine-docetaxel yielded a synergistic effect in SK-UT-1 (CI = 0.59) and an antagonistic effect in SK-UT-1B (CI = 1.36). Dasatinib combined with gemcitabine or docetaxel revealed a synergistic anti-tumor effect (CDI < 1) in both cell lines. The triple drug combination and sequencing revealed conflicting results with a synergistic effect in SK-UT-1B and antagonistic in SK-UT-1. CONCLUSION: Dasatinib inhibits the SRC pathway and yields a synergistic effect with the two-drug combination with either gemcitabine or docetaxel. The value of adding dasatinib to gemcitabine and docetaxel in a triple drug combination is uncertain, but may be beneficial in select uLMS cell lines. Based on our pre-clinical data and known activity of gemcitabine and docetaxel, further evaluation of dasatinib in combination with these agents for the treatment of uLMS is warranted.
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Ancient Lake Ohrid, located in the southern Balkan Peninsula in Macedonia and Albania is characterized by a high degree of endemism and it is considered to be the oldest lake in Europe. But its exact age (between one and ten million years) and also its origin are so far not known. To unravel these uncertainties an ICDP (International Continental Scientific Drilling Program) drilling project (Scientific Collaboration On Past Speciation Conditions in Ohrid (SCOPSCO)), started in April 2013. In addition to the investigations about the age and origin, other paleolimnological studies, e.g., the reconstruction of past climate and of past lake level changes, should be performed with the drilled cores. Used proxies in such paleolimnological studies are, e.g., ostracodes because they respond sensitively to environmental changes but an accurate knowledge of their preferences and tolerances to specific environmental conditions is necessary for this purpose. So far, this knowledge about the, mostly endemic, Ohrid ostracodes was limited. Thus, within the framework of this thesis, ostracodes and a multiplicity of environmental data were collected in Lake Ohrid and its adjacent waters during four field campaigns. In a total of 47 ostracode species could be detected in the entire study area and 32 of them were found alive in Lake Ohrid. Multivariate statistic identified that water depth, salinity, conductivity, pH, and dissolved oxygen were the main determining factors for ostracode distribution in the entire study area. In Lake Ohrid, the distribution was mainly controlled by water depth, water temperature, and pH. Some ostracodes were identified as strong indicator species for important environmental variables, e.g., water temperature and water depth. A distinctive feature of Lake Ohrid was the finding of the ostracode genus Amnicythere whose species normally inhabit oligo-(meso-)haline waters and this could point to a marine origin of the lake. So far, the specialized endemic ostracodes show the highest abundances and the greatest spatial distribution in Lake Ohrid but during the sampling eight widespread species were found for the first time in the lake. They inhabited mainly the northern part of the lake, where two cities are located and industry and agriculture play a major role, and they were limited to water depths above 50 m and this could be an evidence for an increasing anthropogenic pressure because widespread ostracode species often replace endemic species. To unravel the human impact on Lake Ohrid during the last decades short sediment cores were taken and the multi-proxy study indicated that the lake productivity between the early 1920s and the late 1980s was relatively low. Diatom assemblages indicate a rising productivity in the southern part of Lake Ohrid since the mid 1970s and geochemical proxies and ostracodes point to an increasing productivity since the late 1980s in the southern and in the northern part. A slight increase in the productivity continued until 2009. Noticeable is the fact that since the early 1990s, the increasing productivity and the increasing concentrations of heavy metals correspond to a decreasing number of ostracodes in the northern part of Lake Ohrid. Perhaps, this indicates that living conditions in this lake part became less favorable for the mostly endemic ostracode species. Furthermore, the sediment samples from the cores show relatively high concentrations of arsenic, iron, and nickel. Fluctuations in ostracode assemblages from three longer sediment cores, the longest spans approximately 136 ka, taken in Lake Ohrid, correspond to fluctuations in the productivity, in the carbonate content, of the lake level, and of climate changes. Between the marine isotope stage (MIS) 6 and MIS 2 the number of ostracode valves is very low or the valves were completely absent. This corresponds to a low lake productivity, a low carbonate content, and a low lake level. At the onset of the Holocene, the number of valves increased markedly and this correlates with an increased productivity and carbonate content and a warmer climate. But during the Little Ice Age (LIA), the number of valves dropped again and species which prefer warmer waters disappeared completely. This drop corresponds also to a low productivity. After the LIA, the number of species increased again but since 1895 AD a strong and abrupt decrease is visible. A reason for this could be an increase in the heavy metal concentrations.
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Changes in olfactory-mediated behaviour caused by elevated CO2 levels in the ocean could affect recruitment to reef fish populations because larval fish become more vulnerable to predation. However, it is currently unclear how elevated CO2 will impact the other key part of the predator-prey interaction - the predators. We investigated the effects of elevated CO2 and reduced pH on olfactory preferences, activity levels and feeding behaviour of a common coral reef meso-predator, the brown dottyback (Pseudochromis fuscus). Predators were exposed to either current-day CO2 levels or one of two elevated CO2 levels (~600 µatm or ~950 µatm) that may occur by 2100 according to climate change predictions. Exposure to elevated CO2 and reduced pH caused a shift from preference to avoidance of the smell of injured prey, with CO2treated predators spending approximately 20% less time in a water stream containing prey odour compared with controls. Furthermore, activity levels of fish was higher in the high CO2 treatment and feeding activity was lower for fish in the mid CO2treatment; indicating that future conditions may potentially reduce the ability of the fish to respond rapidly to fluctuations in food availability. Elevated activity levels of predators in the high CO2 treatment, however, may compensate for reduced olfactory ability, as greater movement facilitated visual detection of food. Our findings show that, at least for the species tested to date, both parties in the predator-prey relationship may be affected by ocean acidification. Although impairment of olfactory-mediated behaviour of predators might reduce the risk of predation for larval fishes, the magnitude of the observed effects of elevated CO2 acidification appear to be more dramatic for prey compared to predators. Thus, it is unlikely that the altered behaviour of predators is sufficient to fully compensate for the effects of ocean acidification on prey mortality.
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A succession of 23 sub-millimetre to maximum 12-mm-thick, mostly flood-triggered detrital layers, deposited between 1976 and 2005, was analysed in 12 varved surface sediment cores from meso-scale peri-alpine Lake Mondsee applying microfacies and high-resolution micro X-ray fluorescence analyses. Detailed intrabasin comparison of these layers enabled identification of (i) different source areas of detrital sediments, (ii) flood-triggered sediment flux and local erosion events, and (iii) seasonal differences of suspended flood sediment distribution within the lake basin. Additional calibration of the detrital layer record with river discharge and precipitation data reveals different empirical thresholds for flood layer deposition for different parts of the basin. At proximal locations detrital layer deposition requires floods exceeding a daily discharge of 40 m**3/s, whereas at a location 2 km more distal an hourly discharge of 80 m**3/s and at least 2 days of discharge above 40 m**3/s are necessary. Furthermore, we observe a better correlation between layer thickness and flood amplitude in the depocentre than in distal and proximal areas of the basin. Although our results are partly site-specific, the applied dual calibration approach is suitable to precisely decipher flood layer formation processes and, thereby, improve the interpretation of long flood time series from lake sediments.
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Particle fluxes at the Cape Verde Ocean Observatory (CVOO) in the eastern tropical North Atlantic for the period December 2009 until May 2011 are discussed based on bathypelagic sediment trap time-series data collected at 1290 and 3439 m water depth. The typically oligotrophic particle flux pattern with weak seasonality is modified by the appearance of a highly productive and low oxygen (minimum concentration below 2 µmol kg**-1 at 40 m depth) anticyclonic modewater eddy (ACME) in winter 2010. The eddy passage was accompanied by unusually high mass fluxes of up to 151 mg m**-2 d**-1, lasting from December 2009 to May 2010. Distinct biogenic silica (BSi) and organic carbon flux peaks of ~15 and 13.3 mg m**-2 d**-1, respectively, were observed in February-March 2010 when the eddy approached the CVOO. The flux of the lithogenic component, mostly mineral dust, was well correlated with that of organic carbon, in particular in the deep trap samples, suggesting a tight coupling. The lithogenic ballasting obviously resulted in high particle settling rates and, thus, a fast transfer of epi-/meso-pelagic signatures to the bathypelagic traps. We suspect that the two- to three-fold increase in particle fluxes with depth as well as the tight coupling of mineral dust and organic carbon in the deep trap samples might be explained by particle focusing processes within the deeper part of the eddy. Molar C : N ratios of organic matter during the ACME passage were around 18 and 25 for the upper and lower trap samples, respectively. This suggests that some productivity under nutrient (nitrate) limitation occurred in the euphotic zone of the eddy in the beginning of 2010 or that a local nitrogen recycling took place. The d15N record showed a decrease from 5.21 to 3.11 per mil from January to March 2010, while the organic carbon and nitrogen fluxes increased. The causes of enhanced sedimentation from the eddy in February/March 2010 remain elusive, but nutrient depletion and/or an increased availability of dust as a ballast mineral for organic-rich aggregates might have contributed. Rapid remineralisation of sinking organic-rich particles could have contributed to oxygen depletion at shallow depth. Although the eddy formed in the West African coastal area in summer 2009, no indications of coastal flux signatures (e.g. from diatoms) were found in the sediment trap samples, confirming the assumption that the suboxia developed within the eddy en route. However, we could not detect biomarkers indicative of the presence of anammox (anaerobic ammonia oxidation) bacteria or green sulfur bacteria thriving in photic zone suboxia/hypoxia, i.e. ladderane fatty acids and isorenieratene derivatives, respectively. This could indicate that suboxic conditions in the eddy had recently developed and/or the respective bacterial stocks had not yet reached detection thresholds. Another explanation is that the fast-sinking organic-rich particles produced in the surface layer did not interact with bacteria from the suboxic zone below. Carbonate fluxes dropped from -52 to 21.4 mg m**-2 d**-1 from January to February 2010, respectively, mainly due to reduced contribution of shallow-dwelling planktonic foraminifera and pteropods. The deep-dwelling foraminifera Globorotalia menardii, however, showed a major flux peak in February 2010, most probably due to the suboxia/hypoxia. The low oxygen conditions forced at least some zooplankton to reduce diel vertical migration. Reduced "flux feeding" by zooplankton in the epipelagic could have contributed to the enhanced fluxes of organic materials to the bathypelagic traps during the eddy passage. Further studies are required on eddy-induced particle production and preservation processes and particle focusing.
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The Paleo- to Meso-Proterozoic Jabiluka unconformity related uranium mine is located within the Alligator River Uranium Field, found in the Northern Territories, Australia. The uranium ore is hosted in the late middle Paleoproterozoic Cahill Formation, which is unconformably overlain by a group of unmetamorphosed conglomerates known as the Kombolgie subgroup. The Kombolgie subgroup provided the source for oxidized basinal brines, carrying U as the mobile form U(VI), which interacted with reducing lithologies in the Cahill formation, thus reducing U(VI) to the solid U(IV), and leading to the precipitation of uraninite (UO2). In order to characterize fluid interaction with the ore body and compare that to areas without mineralization, several isotopic tracers were studied on a series of clay samples from drill core at Jabiluka as well as in barren areas throughout the ARUF. Among the potential tracers, three were selected: U (redox sensitive and recent fluid mobilization), Fe (redox sensitive), and Li (fractionated by hydrothermal fluids and adsorption reactions). δ238U values were found to be closely linked to the mineralogy, with samples with higher K/Al ratios (indicating high illite and low chlorite concentrations) having higher δ238U values. This demonstrates that 235U preferentially absorbs onto the surface of chlorite during hydrothermal circulation. In addition, δ234U values lie far from secular equilibrium (δ234U of 30‰), indicating there was addition or removal of 234U from the surface of the samples from recent (<2.5Ma) interactions of mobile fluids. δ57Fe values were found to be related to lithology and spatially to known uranium deposits. Decreasing δ57Fe values were found with increasing depth to the unconformity in a drill hole directly above the ore zone, but not in drill holes in the barren area. Similarly to δ238U, δ7Li is found to correlate with mineralogy, with higher δ7Li values associated with samples with more chlorite. In addition, higher δ7Li values are found at greater depth throughout the basin, indicating that the direction of the mineralizing fluid circulation was upwards from the Cahill formation to the Kombolgie subgroup.
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Energy saving, reduction of greenhouse gasses and increased use of renewables are key policies to achieve the European 2020 targets. In particular, distributed renewable energy sources, integrated with spatial planning, require novel methods to optimise supply and demand. In contrast with large scale wind turbines, small and medium wind turbines (SMWTs) have a less extensive impact on the use of space and the power system, nevertheless, a significant spatial footprint is still present and the need for good spatial planning is a necessity. To optimise the location of SMWTs, detailed knowledge of the spatial distribution of the average wind speed is essential, hence, in this article, wind measurements and roughness maps were used to create a reliable annual mean wind speed map of Flanders at 10 m above the Earth’s surface. Via roughness transformation, the surface wind speed measurements were converted into meso- and macroscale wind data. The data were further processed by using seven different spatial interpolation methods in order to develop regional wind resource maps. Based on statistical analysis, it was found that the transformation into mesoscale wind, in combination with Simple Kriging, was the most adequate method to create reliable maps for decision-making on optimal production sites for SMWTs in Flanders (Belgium).
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Visualization and interpretation of geological observations into a cohesive geological model are essential to Earth sciences and related fields. Various emerging technologies offer approaches to multi-scale visualization of heterogeneous data, providing new opportunities that facilitate model development and interpretation processes. These include increased accessibility to 3D scanning technology, global connectivity, and Web-based interactive platforms. The geological sciences and geological engineering disciplines are adopting these technologies as volumes of data and physical samples greatly increase. However, a standardized and universally agreed upon workflow and approach have yet to properly be developed. In this thesis, the 3D scanning workflow is presented as a foundation for a virtual geological database. This database provides augmented levels of tangibility to students and researchers who have little to no access to locations that are remote or inaccessible. A Web-GIS platform was utilized jointly with customized widgets developed throughout the course of this research to aid in visualizing hand-sized/meso-scale geological samples within a geologic and geospatial context. This context is provided as a macro-scale GIS interface, where geophysical and geodetic images and data are visualized. Specifically, an interactive interface is developed that allows for simultaneous visualization to improve the understanding of geological trends and relationships. These developed tools will allow for rapid data access and global sharing, and will facilitate comprehension of geological models using multi-scale heterogeneous observations.
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In the Jakarta Metropolitan Region (JMR), the lack of co-ordination and appropriate governance has resulted in paralyzing traffic jams at the metropolitan scale that cannot be resolved by a single government entity. The issue of metropolitan governance is especially crucial here as the JMR lacks an established and formally pre-designed system of governance (e.g., in a constitution or other legal regulations). Instead, it relies on the interaction, coordination and cooperation of a multitude of different stakeholders, ranging from local and regional authorities to private entities and citizens. This chapter offers a discussion on the various governance approaches relating to an appropriate institutional design required for transportation issues at the metropolitan scale. The case used is a regional Bus Rapid Transit (BRT) system as an extension to the metropolitan transport system. Institutional design analysis is applied to the case and three possible improvements - i) a ‘Megapolitan’ concept, ii) a regional spatial plan and iii) inter-local government cooperation; were identified that correspond to current debates on metropolitan governance approaches of regionalism, localism and new regionalism. The findings, which are relevant to similar metropolitan regions, suggest that i) improvements at the meso-level of institutional design are more readily accepted and effective than improvements at the macro-level and ii) that the appropriate institutional design for governing metropolitan transportation in the JMR requires enhanced coordination and cooperation amongst four important actors - local governments, the regional agency, the central government, and private companies.
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Migration is as old as humanity, but since the 1990s migration flows in Western Europe have led to societies that are not just multicultural but so-called «super-diverse». As a result, Western towns now have very complex social structures, with amongst others large amounts of small immigrant communities that are in constant change. In this paper we argue that for social workers to be able to offer adequate professional help to non-native residents in town, they will need balanced view of ‘culture’ and of the role culture plays in social aid. Culture is never static, but is continually changing. By teaching social workers about how to look at cultural backgrounds of immigrant groups and about the limitations of then role that culture plays in communication, they will be better equipped to provide adequate aid and will contribute to making various groups grow towards each other and to avoid people thinking in terms of ‘out-group-homogeneity’. Nowadays, inclusion is a priority in social work that almost every social worker supports. Social workers should have an open attitude to allow them to approach every individual as a unique person. They will see the other person as the person they are, and not as a part of a specific cultural group. Knowledge about the others makes them see the cultural heterogeneity in every group. The social sector, though, must be aware not to fall into the trap of the ‘inclusion mania’! This will cause the social deprivation of a particular group to be forgotten. An inclusive policy requires an inclusive society. Otherwise, this could result in even more deprivation of other groups, already discriminated against. Emancipation of deprived people demands a certain target-group policymaking. Categorized aid will raise efficiency of working with immigrants and of acknowledging the cultural identity of the non-natives group. It will also create the possibility to work on fighting social deprivation, in which most immigrants can be found.