5,142 research outputs found
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Schematic bus transit maps for the web using genetic algorithms
Dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science in Geospatial TechnologiesThe octilinear schematic map, layout recognized worldwide in metro maps, is an
important transit informative tool. This research investigates how algorithms for the
visualization of schematic maps can be availed in mobile web devices context in
order to empower the efficiency in transmitting information of bus transit maps. A
genetic algorithm for path octilinear schematization technique has been used and
tested to create the schematic data. Location-based and interactivity functionalities
were embedded to the resulting digital maps in order to create personalized maps to
meet specific user needs. A prototype of a web application and real transit data of the
city of Castellón in Spain was used to test the methodology. The results have shown
that real time schematizations open possibilities concerning usability that add extra
value to schematic transit maps. Additionally, suggested improvements have been
made to the genetic algorithm and performance tests show that genetic algorithms are
adequate, in terms of efficiency, to sketch bus transit maps automatically
Brazil and the Afro-Asian World: a Decolonial Approach
The Brazilian path to political emancipation that culminated two centuries ago was a rather peculiar one. After becoming the head of the Portuguese empire in 1808, Brazil became an independent country under the rule of the same royal family that governed the colony. The purpose of this paper is to discuss how the Brazilian independence did not entail a delinking from Portugal, due to which the Brazilian Western identity was taken for granted. We will also discuss how this absence of delinking had consequences in the long run. Despite the Brazilian colonial past, several intellectuals and foreign policymakers assumed the Brazilian Western identity and made disdainful and hostile comments when writing on the Afro-Asian decolonization process
The role of the anaphase-promoting complex/cyclosome in plant growth
The anaphase-promoting complex/cyclosome (APC/C) is a multi-subunit E3 ubiquitin ligase that plays a major role in the progression of the eukaryotic cell cycle. This unusual protein complex targets key cell cycle regulators, such as mitotic cyclins and securins, for degradation via the 26S proteasome by ubiquitination, triggering the metaphase-to-anaphase transition and exit from mitosis. Because of its essential role in cell cycle regulation, the APC/C has been extensively studied in mammals and yeasts, but relatively less in plants. Evidence shows that, besides its well-known role in cell cycle regulation, the APC/C also has functions beyond the cell cycle. In metazoans, the APC/C has been implicated in cell differentiation, disease control, basic metabolism and neuronal survival. Recent studies also have shed light on specific functions of the APC/C during plant development. Plant APC/C subunits and activators have been reported to play a role in cellular differentiation, vascular development, shoot branching, female and male gametophyte development and embryogenesis. Here, we discuss our current understanding of the APC/C controlling plant growth
Magnetic Fields and the Formation of Aspherical Planetary Nebulae
The general evolution of stars with initial mass between 0.8 and 8 solar masses is believed to be well understood until the last stages, when significant mass loss starts. However, an initially spherical star may evolve into an asymmetrical planetary nebula (PN), whereas the underlying mechanism to this process remains as a puzzle. Until about a decade ago, it was believed that stars in the asymptotic giant branch (AGB) phase were still spherically symmetric. Nevertheless, observations performed in the last years show that, for some sources, elongated and asymmetrical envelopes can already be detected during the AGB phase. In the following pre-PN and planetary nebula phases, a variety of morphologies is observed, and the sources are classified into round, elliptical/elongated, bipolar, quadrupolar, multipolar, spiral, collimated lobes and irregular. It is unknown which mechanism or set of mechanisms is responsible for this change of morphology, making this topic to be one of the most discussed by the evolved stars community. To shed some light on this problem, three AGB stars (IK Tau, R Scl, and V644 Sco) and one red supergiant (VY CMa) were observed at optical wavelengths. We analyzed their dust scattered emission and searched for signs of upcoming asymmetries in their circumstellar envelope. The observations in R band reveal that the dust envelope of the AGB star IK Tau has a global elliptical morphology, and the presence of a central waist is discussed. The observation of VY CMa shows a complex morphology in the very extended nebula that surrounds the source. Furthermore, for the first time the detached shell around the AGB star V644 Sco was imaged, allowing a better investigation of the mass-loss episodes of the source. The detached shell around R Scl was also imaged and analyzed. The results reported in this thesis add together with previous works, confirming that the loss of spherical symmetry in the circumstellar envelope of evolved stars can already start during the AGB phase. Moreover, we studied one of the mechanisms that can play a role in the shaping process of the circumstellar envelope of these sources: magnetic fields. For this purpose, we investigated 22 GHz H2O maser observations around five sources: four AGB stars (IK Tau, RT Vir, IRC+60370, and AP Lyn) and one pre-PN (OH231.8+4.2). By analyzing the linear and circular polarization in the masers, we detected the presence of magnetic field in four of these five sources. We measured the field strengths to be from a few tens up to a few hundreds of milligauss in the H2O maser region (at a few tens of astronomical units from the star). Comparing our results with magnetic field measurements from the literature, obtained at different distances with respect to the stars, we tried to determine the most plausible geometry of the magnetic fields for the observed sources. However, it is not yet definitive if the observed fields are toroidal, poloidal, or dipole. The influence of magnetic fields on the shaping process of the circumstellar envelope of evolved stars is still unclear, but their detection around AGB stars, pre-PNe and PNe supports that they might play a role in the process. More measurements of the strength of the fields, also at different distances to the stars, and the investigation of the geometry of the fields are fundamental for providing better constraints to models, and for the better understanding of this subject
Mais diplomas, mais produtividade?: Uma análise inicial entre países e setores
Analisa a relação entre a escolaridade e a produtividade. A literatura coloca que o investimento em educação, através do aumento da produtividade, tem efeitos positivos em termos de crescimento econômico. Assim, este trabalho buscou investigar tal relação a partir de uma ampla base de dados para diversos países ao longo de um período de quinze anos. Foram realizadas análises econométricas para o caso da produtividade agregada e para os setores agropecuário, industrial e de serviços tradicionais, híbridos e modernos. Foi encontrado que uma maior proporção de horas de trabalho qualificado (realizado por trabalhadores com ensino superior) apresenta relação positiva com a produtividade para o caso agregado e todos os casos setoriais, exceto o industrial. Além disso, como resultado, foi percebido que, ao longo do tempo, a proporção de horas de trabalho qualificado não influenciava mais a produtividade com a mesma relevância
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