Nas topologias de redes WDM-PON (Wavelength Division Multiplexed Passive Optical Network) baseadas em transmissores colorless, isto é, transmissores que possam operar em uma grande gama de comprimentos de onda, que empreguem técnica de auto-alimentação e reuso de comprimento de onda, tem despertado grande interesse devido a sua comprovada eficiência, granularidade e custo reduzido em relação às alternativas. Entretanto, o alcance destas redes é limitado pelo emprego de remodulação, devido a dependência existente com a qualidade dos sinais a serem remodulados. Neste cenário, mantendo-se uma melhor relação custo-benefício, taxas de operação típicas são da ordem de 1,25, e 2,5 Gb/s (20 quilômetros). Neste trabalho é investigada uma nova topologia que combina as técnicas de auto-alimentação e reuso de comprimento de onda, bem como, utiliza um circuito de dupla cavidade óptica, possibilitando um reforço no apagamento óptico e manutenção do estado da polarização no percurso de recirculação da cavidade externa, objetivando uma melhora na qualidade dos sinais a serem remodulados, possibilitando altas taxas de transmissão e um maior alcance da rede. Nesta topologia, amplificadores ópticos semicondutores refletivos são utilizados como transmissores colorless, por meio da emissão espontânea amplificada, garantido assim uma redução no custo da rede óptica de acesso. Como metodologia adotada, inicialmente foram realizadas caracterizações ópticas no ambiente de simulação, validação da palheta configurada no simulador com resultados experimentais e avaliações da topologia em taxas simétricas de 1,25 Gb/s. Ademais, são conduzidas análises comparativas entre a topologia proposta frente a topologias disponíveis na literatura no estado da arte. Com os resultados obtidos, acredita-se que essa proposta atende aos requisitos de capacidade agregada e custo reduzido, podendo alcançar taxas de transmissão de até 10 Gb/s utilizando transmissores de baixa complexidade, características essenciais para impulsionar a implementação de redes de acesso óptico. / WDM-PON topologies based on colorless transmitters employing self-seeding and wavelength-reuse techniques have attracted a great deal of interest because of its well known efficiency, granularity and reduced cost, when compared to other alternatives in the literature. Nevertheless, the network reach is limited by the use of remodulation scheme. Maintaining an adequate cost-benefit relation requires typical operating rates of the order of 1.25 Gb/s to 2.5 Gb/s over 20 km of SSMF. In the above framework, we investigate a new topology which combines self-seeding and wavelength-reuse techniques, but also employs a scheme to reinforce the data erasure in the optical carrier, simultaneously providing state of polarization (SOP) maintenance in the external cavity recirculation path. The proposed configuration improves the quality of the signals to be remodulated, thus allowing high rate and broader reach. Specifically, in our work, reflective semiconductor optical amplifiers are employed as colorless transmitters, by using their own amplified spontaneous emission as a seed to provide the optical carrier. Optical analysis were performed in a simulation environment, including self-seeding layout validation by comparison to experimental results at the symmetric transmission rate of 1.25 Gb/s. Next, comparative analysis are conducted between the topology proposed in this work and topologies in the state of the art, found in the literature. According to the results, we believed that the proposal meets the requirements of aggregate capacity and reduced cost, being able to reach transmission rates of up to 10 Gb/s by using transmitters of low complexity, essential features to drive optical access networks implementation.

Made available in DSpace on 2014-08-20T14:06:14Z (GMT). No. of bitstreams: 1 Tese_ Igor_ Valerio.pdf: 990885 bytes, checksum: 6b9bd709ded7ec022e6445c220d43a98 (MD5) Previous issue date: 2008-05-20 / Many selection strategies have contributed for the continuous progress in wheat breeding programs. On the other hand, the main yield component (number of fertile tillers), has still been underexploited. In this sense, in order to investigate this issue, this work was planned to report the state of the art processes involved in tiller production and development. This information was crucial to the design of the next experiments on genotypes contrasting for tiller number and their response in segregating generations, when subjected to artificial crosses. The seeding density influences greatly grain yield, since it is directly related to fertile tiller production potential, and has a direct effect on number of ears per unit area. Likewise, the genotype and environment effects were important for the adjustment of seeding density and maximum yield obtained. It is essential that the best seeding rate be found for a given genotype at a given location. Genotypes with reduced tillering potential, revealed a larger buffering effect. However, only at seeding density higher than 400 seeds m-2. The genotypes with high tillering potential revealed the best grain production performance at low seeding density. However, these genotypes have a long developing cycle, with high tillering senescence rate when subjected to high seeding density. The use of genotypes contrasting for tillering ability enabled one to find in the segregating generations, wide genetic variability for tillering ability and consequently for the yield components. The selection for high or low number of tillers and the bulk selection vary their efficiency with the crop management system to which the segregating population is subjected. The best grain yield performance is achieved in the selection for low number of tillers, with high average grain weight under competition. / Diversas estratégias de seleção têm contribuído para o contínuo progresso da cultura do trigo nos programas de melhoramento. Por outro lado, o principal componente do rendimento (número de afilhos férteis), ainda revela severos questionamentos sobre o seu real aproveitamento em condições de lavoura. Neste sentido, por entender a fundamental importância deste assunto, foi buscado neste trabalho, primeiramente, relatar o estado da arte dos processos envolvidos na produção e desenvolvimento de afilhos, o que permitiu trazer, posteriormente, contribuições importantes para o desenvolvimento dos demais trabalhos em genótipos contrastantes para afilhamento e a resposta destes, em gerações segregantes, quando submetidos a cruzamentos artificiais. A densidade de semeadura revela a maior variação na produtividade da cultura, uma vez que está diretamente relacionada ao potencial do genótipo em produzir afilhos férteis, com efeito direto no número de espigas produzidas por unidade de área. Da mesma forma, o efeito do genótipo e do ambiente foram determinantes na densidade de semeadura obtida com o máximo rendimento de grãos, destacando a necessidade de implementar, para cada condição de cultivo e genótipo utilizado, uma densidade ideal. Genótipos com reduzido potencial de afilhamento revelam o maior efeito compensatório, porém, com aproveitamento somente em densidade superior a 400 sementes m-2. Os genótipos com elevado potencial de afilhamento revelam o melhor comportamento para rendimento de grãos em reduzidas densidades, porém, evidenciam um longo ciclo de desenvolvimento, com senescência elevada de afilhos quando submetidos a elevadas densidades. O uso de genótipos contrastantes para o afilhamento, possibilitou encontrar em gerações segregantes, ampla variabilidade genética para o caráter e consequentemente para os componentes do rendimento. A seleção para elevado ou reduzido número de afilhos e a seleção em bulk são dependentes do sistema de manejo em que a população segregante for submetida. O melhor desempenho em rendimento de grãos é alcançado na seleção para reduzido número de afilhos, com média elevada para massa de grãos em competição.

Particle Image Velocimetry (PIV) is an optical fluid measurement technique used to obtain velocity measurements. Two PIV systems were used to capture data simultaneously and measurement error for the MS PIV system is calculated. An investigation of error distribution is performed to determine when uncertainty estimations fail for the CS PIV-UQ method. Investigation of when results from multi pass PIV processing are achieve were performed so that reliable uncertainty estimations are produced with the CS method. An investigation was also performed which determined that error distributions in PIV systems are correlated with flow shear and particle seeding density. Correlation of random errors in space was also performed at the jet core and shear regions of the flow. It was found that in flow regions with large shear that error distributions were non-Gaussian. It was also found in regions of large shear that CS uncertainty results did not match the error. For multi-pass PIV processing with 50% and 75% IW overlap it was found that 4 and 6 passes should be used, respectively, in order for CS uncertainty estimations to be reliable. It was also found that the correlation of random errors in space is much larger in shear regions of the jet flow than in the jet core.

No description available.

<p>Tauopathies are neurodegenerative diseases defined by the accumulation of pathological tau protein in neurons and glia. Alzheimer’s disease (AD), the most common tauopathy, is characterized by the presence of neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein aggregates in neurons. Emerging evidence suggests that the NFT burden correlates with neuron death and cognitive decline, contributing to disease progression. Besides AD, a similar deposition of tau inclusions is found to be associated with neurodegeneration in the brains of patients with other tauopathies including progressive supranuclear palsy, corticobasal degeneration, and Pick’s disease. These diseases display clinical, biochemical, and neuropathological heterogeneity. Little is known about how tau aggregation can lead to varied phenotypes in tauopathies, and there is no disease-modifying treatment. Thus, it is necessary to understand the role of diverse tau proteoforms in tauopathies for the development of new therapeutics to treat tauopathies, including AD.</p> <p>In the studies summarized in Chapter 2, we investigated how the molecular diversity of tau proteoforms could impact antibody-based assays of a phospho-tau variant serving as an AD biomarker. A tau variant phosphorylated on threonine 181 (pT181-tau) has been widely investigated as a potential AD biomarker in cerebrospinal fluid (CSF) and blood. pT181-tau is present in NFTs of AD brains, and CSF levels of pT181-tau correlate with overall NFT burden. Various immuno-based analytical methods, including Western blotting and ELISA, have been used to quantify pT181-tau in human biofluids. The reliability of these methods depends on the affinity and binding specificity of the antibodies used to measure pT181-tau levels. Although both of these properties could in principle be affected by phosphorylation within or near the antibody’s cognate antigen, such effects have not been extensively studied. Here, we developed a bio-layer interferometry (BLI)-based analytical assay to assess the degree to which the affinity of pT181-tau antibodies is altered by the phosphorylation of serine or threonine residues near the target epitope. Our results revealed that phosphorylation near T181 negatively affected the binding of pT181-tau antibodies to their cognate antigen to varying degrees. In particular, two of three antibodies tested showed a complete loss of affinity for the pT181 target when S184 or S185 was phosphorylated.</p> <p>In the studies outlined in Chapter 3, we examined the relative abilities of different tau proteoforms to induce seeded tau aggregation and to themselves undergo seeded aggregation in cultured cells. Accumulating evidence suggests that tau aggregates, including NFTs, spread in a stereotypical pattern across neuroanatomically connected brain regions. This spreading phenomenon is thought to occur via a prion-like mechanism involving the release of tau aggregates from a diseased neuron into the extracellular space, aggregate uptake by neighboring healthy neurons, and the formation of new aggregates in the cytosol of the recipient cells via a seeding process. Although research over the past decade has revealed key molecular events involved in the cell-to-cell transmission of tau aggregates, the impact of the protein’s domain structure and phosphorylation profile on the efficiency of prion-like propagation remains poorly defined. Here, we compared three tau variants – K18, 0N4R, and 2N4R – in terms of their aggregation and seeding efficiencies in recombinant protein solutions and in cell culture models. Our results revealed that K18 had the highest fibrillization rate and yield among the three tau variants. Recombinant preformed fibrils (PFFs) derived from all three variants had similar seeding efficiencies. Additionally, we investigated the relationship between tau phosphorylation and aggregation. We found that hyperphosphorylated tau did not undergo self-assembly in the absence of heparin, whereas it formed fibrils at low yield in the presence of the cofactor. Moreover, hyperphosphorylated tau PFFs produced under these conditions induced seeded tau aggregation in cell culture.</p> <p>Taken together, these results point to critical roles of tau proteoforms as both AD biomarkers and drivers of disease progression. Our results indicate that the presence of different combinations of phosphorylated residues near a target phospho-tau antigen can affect the accuracy of antibody-based biomarker assays. In addition, the domain structure and phosphorylation profiles of tau proteoforms associated with AD and other tauopathies likely have a profound influence on the evolution of tau pathology in these disorders. Our findings highlight the importance of accounting for the molecular diversity of tau proteoforms in tauopathies and provide valuable insights into molecular determinants influencing tau aggregation and propagation in the brains of patients.</p>

Biologiska läkemedel har under det senaste århundradet utökats, och under de senaste 25 åren så har proportionen av godkända biologiska läkemedel har ökat för behandlingen av sjukdomar, vaccin, och diagnostik. Det finns flera olika mekanismer för protein aggregering, och en av dessa är seeding, vilket innebär aggregering inducerat av tillsatta aggregat eller förekomsten av strukturförändringar i proteinet. I detta examensarbete har två terapeutiska proteiner, Somatropin och en monoklonal antikropp, studerats i form av aggregering. Denna studie har utförts genom att värma en del av proteinlösningen för att bilda aggregat och strukturförändrat protein, och sedan blanda detta med nativt protein till olika volymprocent. Dessa lösningar förvarades i olika temperaturer, 4°C, RT och 40°C för att undersöka temperaturberoendet. Med Dynamic Light Scattering (DLS) mättes storleksfördelningen och medelstorleken på proteinet, vilket visade att de seedade proverna ökade i medelstorlek med tiden. Detta indikerar att seedingen inducerade aggregering med tiden. / Biological pharmaceuticals have expanded their use over the last decade, and during the recent 25 years, the proportion of approved biologics has increased for the treatment of diseases, vaccines, and diagnostics. There are several aggregation mechanisms, and one is seeding, i.e., aggregation induced by pre-formed aggregates or the presence of conformational changed proteins. In this master thesis, two therapeutic proteins, Somatropin and one monoclonal antibody have been studied in terms of aggregation. The study has been performed by heating a part of a protein solution to induce aggregation and mixing this with native protein in different volume percentages. These were stored in different temperatures, 4°C, RT, and 40°C, to investigate the temperature dependence. With Dynamic light scattering (DLS), the size distribution and the average-sized particles were measured. This showed that there was a growth of average size in the seeded samples with time. This indicates that the seeding induced aggregation with time.

Die Parkinson-Krankheit (PA) ist durch Fehlfaltung und Aggregation von Alpha-Synuklein (a-Syn) charakterisiert. Dieses zeigt Ähnlichkeiten mit dem Verhalten von Prionen bei transmissiblen spongiformen Enzephalopathien. Pathologische a-Syn Aggregate propagieren, wie Prione, über selbsttempliertes Seeding (Keimung). Aufgrund von Studien, die eine Übertragbarkeit der a-Syn Seeding-Aktivität nachgewiesen haben, war das Ziel dieser Dissertation die Risikobewertung potenzieller Übertragungen von a-Syn Seeds zu verbessern. Die Menge an Seeding-aktiven a-Syn in Hirn- und Magengewebe von PA-Patienten wurde durch Real-Time Quaking-Induced Conversion (RT-QuIC) Assays quantifiziert. Die Ergebnisse zeigten in beiden Geweben hohe Seeding-Titer, was die Notwendigkeit für effektive Inaktivierungsprotokolle unterstreicht. Die Quantifizierung des Effekts der Dampfsterilisation bei 134 °C ergab eine unerwartet hohe, Prion-übersteigende, Resistenz von PA-assoziiertem a-Syn gegen Dampfsterilisation. Die Verlängerung der Sterilisationsdauer führte zu einem identischen Reduktionsfaktor des Seeding-Titers. Fourier-Transform-Infrarot (FT-IR) Spektroskopie wurde genutzt, um eine Stammdifferenzierung zwischen a-Syn Aggregaten aus PA-assoziierten transgenen Mausmodellen mit den a-Syn-Mutationen A30P und A53T vorzunehmen, die für familiäre PA beim Menschen prädisponieren. Etablierte Protokolle zur Untersuchung von Prionstämmen (PS) wurden verfeinert um 5 hamsteradaptierte PS zu vergleichen: 263K, 22A-H, BSE-H, CWD-H, und ME7-H. Hier führte die Zugabe des Farbstoffs Kongo Rot zu spektralen Veränderungen in einigen PS und resultierte in der erfolgreichen Unterscheidung aller untersuchten PS. Mittels PMCA wurden die winzigen Mengen an a-Syn Aggregaten aus Maus-Hirngeweben für die anschließende FT-IR Spektroskopie vervielfältigt. Die Spektren der A30P und A53T a-Syn Aggregate wiesen allerdings keine Unterschiede auf, und der Zusatz von Kongo Rot hatte keinen Effekt auf die Spektren. / Parkinson’s Disease (PD) is characterized by misfolding and aggregation of Alpha-Synuclein (a-Syn), which shows similarities to the behavior of prions in transmissible spongiform encephalopathies (TSEs). Pathological a-Syn aggregates, like prions, propagate by self-templated seeding. Due to reports of transmissible seeding activity of a-Syn, the goal of this thesis was to improve risk assessment of potential a-Syn seed transmissions. Real-Time Quaking-Induced Conversion (RT-QuIC) assays were used to quantify seeding active a-Syn in brain and stomach tissue of PD patients. The results show high seeding titers in both tissues, highlighting the need for effective inactivation protocols. Quantification of the effects of steam sterilization at 134 °C on the seeding activity of cerebral PD-associated a-Syn revealed a surprisingly high, prion-exceeding, resistance to steam sterilization. Extended duration of steam sterilization has no further inactivation effect and led to an identical reduction factor of the seeding activity titer. Fourier-Transform Infrared (FT-IR) spectroscopy was used to attempt strain differentiation between a-Syn aggregates from PD-associated transgenic mouse models with the a-Syn A30P and A53T mutations which predispose for familial forms of PD in humans. Established protocols for prion strain examination were refined to compare five hamster-adapted prion strains: 263K, 22A-H, BSE-H, CWD-H, and ME7-H. Here, the addition of a dye (Congo Red) led to spectral changes of some prion strains and resulted in the successful distinction of all investigated prion strains. To increase the tiny amounts of a-Syn aggregates in the brain tissues of mice, PMCA was used to multiply these aggregates for subsequent FT-IR spectroscopy. However, the spectra of the A30P and A53T a-Syn aggregates were undistinguishable, and the addition of CR had no significant effect on the spectra.

La restauration écologique a été identifiée comme une approche permettant notamment de ralentir la perte de biodiversité et de maintenir tous les biens et services issus de cette biodiversité desquels dépend le bien être de notre civilisation actuelle. Cette restauration des écosystèmes se base sur des connaissances provenant à la fois de l'écologie des communautés et de l’écologie de la restauration. Les objectifs de la thèse sont donc de comprendre la dynamique d’une steppe méditerranéenne après changements d’usage ainsi que la mise en oeuvre de techniques qui pourraient être appliquées à la restauration de cet écosystème après une perturbation anthropique sévère. La thèse a pour objet d'étude la steppe méditerranéenne de la plaine de Crau, et notamment d’anciennes cultures pour étudier la recolonisation spontanée après perturbation et le projet de réhabilitation à grande échelle de Cossure pour les expérimentations sur les techniques de restauration. En ce qui concerne la dynamique après une perturbation anthropique exogène sévère, nous avons confirmé la faible résilience de la communauté végétale steppique à la fois à moyen (30-40 ans) et long terme (150 ans), tandis que les paramètres du sol et le taux d'infestation des mycorhizes sont résilients sur le long terme. En outre, nous avons confirmé le rôle joué par les trois filtres dans la recolonisation des communautés végétales. En ce qui concerne la steppe de la Crau, la recolonisation est déterminée en premier par le filtre abiotique, puis par le filtre de dispersion et enfin par le filtre biotique. Compte tenu de la faible résilience de la communauté, nous avons testé plusieurs techniques de restauration appliquées à grande échelle au sein du projet de réhabilitation de Cossure: le semis d’espèces nurses, l'étrépage de sol, le transfert de foin et le transfert de sol. Afin d'évaluer l'efficacité des techniques de restauration, nous avons développé des indices pour mesurer « l 'intégrité » de la structure de la communauté permettant de distinguer les abondances inférieures des abondances supérieures par rapport à la communauté de référence. Les meilleurs résultats ont été obtenus avec le transfert du sol, suivi par l’étrépage de sol, puis le semis d’espèces nurses et enfin le transfert de foin. Ces résultats ont toutefois confirmé la difficulté de restaurer totalement la communauté végétale steppique. Les recherches menées au sein de cette thèse montrent que les connaissances actuelles en matière de restauration écologique permettent de restaurer au moins partiellement certaines composantes de cet écosystème, mais suggèrent de mettre un maximum de moyens pour la conservation in situ des habitats naturels plutôt que de devoir les restaurer après qu'ils aient été détruits / Ecosystem restoration has been identified as one approach to slow down the loss of biodiversity and to protect all the biodiversity-based goods and services from which humankind benefits. Restoration feeds from knowledge coming from both community ecology and restoration ecology. The objectives of the thesis are to provide insights on both the dynamics of a mediterranean steppe after changes in land-use and the implementation of techniques which could be applied to restore this ecosystem after severe anthropogenic disturbances. The thesis takes as a study object the La Crau Mediterranean steppe, and especially former cultivated fields to study the recovery after cultivation and the Cossure large scale rehabilitation project to experiment rehabilitation and restoration techniques. Concerning dynamics after severe exogenous anthropogenic disturbances, we confirmed the low resilience of the steppe plant community both at mid- (30-40 years) and long-term (150 years) while the resilience of soil parameters and mycorrhizal infestation rate are effective on the long-term. Moreover we confirmed the role played by the three filters in the plant community recovery and found that for the La Crau steppe, this is firstly driven by the abiotic filter, then by the dispersion filter and finally by the biotic filter. Given this low resilience, we tested several restoration techniques applied at large-scale within the Cossure rehabilitation project: nurse species seeding, topsoil removal, hay transfer and soil transfer. In order to assess the efficiency of restoration techniques we developed indices to measure the community structure integrity, disentangling lower and higher abundances compared to the reference. The best results were obtained with soil transfer, followed by topsoil removal, then nurse species seeding and finally hay transfer. The research conducted for this thesis shows that current knowledge in ecological restoration makes it possible to restore at least partially some La Crau ecosystem components, but ought to lead us to understand the importance of in situ conservation of natural habitats as a better alternative to restore them after they were destroyed

Two of the most important environmental challenges in the 21st century are to protect the quality of fresh water resources and to utilize renewable energy sources to lower greenhouse gas emissions. This study contributes to the solution of the first challenge by providing methodologies for optimal design of real-time water quality monitoring systems and interpretation of data supplied by the monitoring system to identify potential pollution sources in river networks. In this study, the optimal river water quality monitoring network design aspect of the overall monitoring program is addressed by a novel methodology for the analysis of this problem. In this analysis, the locations of sampling sites are determined such that the contaminant detection time is minimized for the river network while achieving maximum reliability for the monitoring system performance. The data collected from these monitoring stations can be used to identify contamination source locations. This study suggests a methodology that utilizes a classification routine which associates the observations on a contaminant spill with one or more of the candidate spill locations in the river network. This approach consists of a training step followed by a sequential elimination of the candidate spill locations which lead to the identification of potential spill locations. In order to contribute the solution of the second environmental challenge, this study suggests utilizing available excess energy in water distribution systems by providing a methodology for optimal design of energy recovery systems. The energy recovery in water distribution systems is possible by using micro hydroelectric turbines to harvest available excess energy inevitably produced to satisfy consumer demands and to maintain adequate pressures. In this study, an optimization approach for the design of energy recovery systems in water distribution networks is proposed. This methodology is based on finding the best locations for micro hydroelectric plants in the network to recover the excess energy. Due to the unsteady nature of flow in water distribution networks, the proposed methodology also determines optimum operation schedules for the micro turbines.

No description available.