16 resultados para channel distributions


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Dissertação para obtenção do Grau de Mestre em Engenharia Civil – Perfil de Estruturas

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This work presents the results of the experimental study of proton induced nuclear reactions in lithium, namely the 7Li(p,α) 4He, 6Li(p,α) 3He and 7Li(p,p)7Li reactions. The amount of 7Li and 6Li identified as primordial and observed in very old stars of the Milky Way galactic halo strongly deviates from the predictions of primordial nucleosynthesis and stellar evolution models which depend, among other factors, on the cross sections of reactions like 7Li(p,α) 4He and 6Li(p,α) 3He. These discrepancies have triggered a large amount of research in the fields of stellar evolution, cosmology, pre-galactic evolution and low energy nuclear reactions. Focusing on nuclear reactions, this work has measured the 7Li(p,α) 4He and 6Li(p,α) 3He reactions cross sections (expressed in terms of the astrophysical S -factor) with higher accuracy, and the electron screening effects in these reactions for different environments (insulators and metallic targets). The 7Li(p,α) 4He angular distributions were also measured. These measurementstook place in two laboratory facilities, in the framework of the LUNA (Laboratory for Undergroud Nuclear Astrophysics) international collaboration, namely the Laboratorio ´ de Feixe de Ioes ˜ in ITN (Instituto Tecnologico ´ e Nuclear) Sacavem, ´ Portugal, and the Dynamitron-TandemLaboratorium in Ruhr-Universitat¨ Bochum, Germany. The ITN target chamber was modified to measure these nuclear reactions, with the design and construction of new components, the addition of one turbomolecular pump and a cold finger. The 7Li(p,α) 4He and 6Li(p,α) 3He reactions were measured concurrently with seven and four targets, respectively. These targets were produced in order to obtain adequate and stable lithium depth profiles. In metallic environments, the measured electron screening potential energies are much higher than the predictions of atomic-physics models. The Debye screening model applied to the metallic conduction electrons is able to explain these high values. It is a simple model, but also very robust. Concerning primordial nucleosynthesis and stellar evolution models, these results are very important as they show that laboratory measurements are well controlled, and the model inputs from these cross sections are therefore correct. In this work the 7Li(p,p)7Li differential cross section was also measured, which is useful to describe the 7Li(p,α) 4He entrance channel.

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IEEE International Symposium on Circuits and Systems, pp. 2258 – 2261, Seattle, EUA

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1st European IAHR Congress,6-4 May, Edinburg, Scotland

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1st European IAHR Congress, 6-4 May, Edinburgh, Scotland

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River Flow 2008, Vol.1

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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 Doutor em Engenharia Electrotécnica e Computadores

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Field Lab in Entrepreneurial Innovative Ventures

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Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/64337/2009 ; projects PTDC/ECM/70652/2006, PTDC/ECM/117660/2010 and RECI/ECM-HID/0371/2012

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Continuous cell lines that proliferate in chemically defined and simple media have been highly regarded as suitable alternatives for vaccine production. One such cell line is the AG1.CR.pIX avian cell line developed by PROBIOGEN. This cell line can be cultivated in a fully scalable suspension culture and adapted to grow in chemically defined, calf serum free, medium [1]–[5]. The medium composition and cultivation strategy are important factors for reaching high virus titers. In this project, a series of computational methods was used to simulate the cell’s response to different environments. The study is based on the metabolic model of the central metabolism proposed in [1]. In a first step, Metabolic Flux Analysis (MFA) was used along with measured uptake and secretion fluxes to estimate intracellular flux values. The network and data were found to be consistent. In a second step, Flux Balance Analysis (FBA) was performed to access the cell’s biological objective. The objective that resulted in the best predicted results fit to the experimental data was the minimization of oxidative phosphorylation. Employing this objective, in the next step Flux Variability Analysis (FVA) was used to characterize the flux solution space. Furthermore, various scenarios, where a reaction deletion (elimination of the compound from the media) was simulated, were performed and the flux solution space for each scenario was calculated. Growth restrictions caused by essential and non-essential amino acids were accurately predicted. Fluxes related to the essential amino acids uptake and catabolism, the lipid synthesis and ATP production via TCA were found to be essential to exponential growth. Finally, the data gathered during the previous steps were analyzed using principal component analysis (PCA), in order to assess potential changes in the physiological state of the cell. Three metabolic states were found, which correspond to zero, partial and maximum biomass growth rate. Elimination of non-essential amino acids or pyruvate from the media showed no impact on the cell’s assumed normal metabolic state.

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Branding Lab

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It’s impossible to neglect the changes that internet and e-commerce caused in the retail sector, by increasing customers’ expectations and forcing retailers to adapt the business to the new digital era. Internet is characterized by the increase in accessibility to everyone, which can be good or not so. For instance, luxury products rely on the sense of exclusivity, instead of being accessible to everyone. Hence, internet represents a challenge for luxury brands once, although they are able to provide a fullness service to their customers, they need to maintain the exclusiveness in which luxury is sustained. Consequently, the appearance of omni-channel was more than a challenge for the luxury sector, in particular, given the need to provide a full integrated experience through different channels. The aim of this dissertation is to find out how important is omni-channel, even in the luxury industry, and how it’s actually implemented based on the case of one of the most successful companies on luxury fashion e-commerce industry – Farfetch. Even though the company started in London, its founder is a Portuguese entrepreneur, and it’s in Portugal where most of its employees work, divided in two offices – Guimarães e Porto. Therefore, a literature review was written on relevant concepts and ideas about luxury, e-commerce and the different channels’ approaches. There were formulated five propositions that were after discussed according to the information gathered about the company and its strategies. In the end, it was possible to identify which propositions are in accordance with theory and which are not, as well as understand which are the most important strategies and trends about omni-channel in the luxury fashion e-commerce sector.