981 resultados para Trophic web structure


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Getting the attention of students has always been a hard task for most teachers. In this context the use of new technologies can be taken into consideration for giving the teacher new means to incentive his students. The tool described in this article gives importance to the opinion of the students for their own evaluation. Thanks to it a group of students from the University of Minho was able to post questions to their colleagues and to evaluate their peer’s works on the discipline of Power Electronics Complement.

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Candida parapsilosis is nowadays an emerging opportunistic pathogen and its increasing incidence is part related to the capacity to produce biofilm. In addition, one of the most important C. parapsilosis pathogenic risk factors includes the organisms\textquoteright selective growth capabilities in hyper alimentation solutions. Thus, in this study, we investigated the role of glucose in C. parapsilosis biofilm modulation, by studying biofilm formation, matrix composition and structure. Moreover, the expression of biofilm-related genes (BCR1, FKS1 and OLE1) were analyzed in the presence of different glucose percentages. The results demonstrated the importance of glucose in the modulation of C. parapsilosis biofilm. The concentration of glucose had direct implications on the C. parapsilosis transition of yeast cells to pseudohyphae. Additionally, it was demonstrated that biofilm related genes BCR1, FKS1 and OLE1 are involved in biofilm modulation by glucose. The mechanism by which glucose enhances biofilm formation is not fully understood, however with this study we were able to demonstrate that C. parapsilosis respond to stress conditions caused by elevated levels of glucose by up-regulating genes related to biofilm formation (BCR1, FKS1 and OLE1).

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Polyurethane thermoplastic elastomer (TPU) nanocomposites were prepared by the incorporation of 1 wt% of high-structured carbon black (HSCB), carbon nanofibers (CNF), nanosilica (NS) and nanoclays (NC), following a proper high-shear blending procedure. The TPU nanofilled mechanical properties and morphology was assessed. The nanofillers interact mainly with the TPU hard segments (HS) domains, determining their glass transition temperature, and increasing their melting temperature and enthalpy. A significant improvement upon the modulus, sustained stress levels and deformation capabilities is evidenced. The relationships between the morphology and the nanofilled TPU properties are established, evidencing the role of HS domains on the mechanical response, regardless the nanofiller type.

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Malaria has still been one of the most important endemic diseases in the Amazonian region. This study presents the impact of human settlements on the structure of Anopheles population. Diversity, abundance, richness and distribution of the genus Anopheles were observed in two areas with different levels of human settlement in the Cantá city, Roraima State, Northern Brazil. The influence of the dry and rainy seasons on mosquito populations was also observed. Mosquito captures were performed between 6:00 and 10:00 pm during the dry (February and November) and rainy (May and August) seasons at four different sites of each area. Among the 11 species of Anopheles identified through the adults' characteristics, An. albitarsis s.l. (45.5%) and An. darlingi (19.2%) were the most abundant in the more intensively anthropized area while An. triannulatus (19.2%) was more common in the less modified area. Other species found were An. nuneztovari (10.9%), An. oswaldoi (2.0%), An. evansae (1.7%), An. brasiliensis (0.6%), An. intermedius (0.3%), An. mediopunctatus (0.5%), An. periassui (0.08%) and An. argyritarsis (0.04%). The highest mosquitoes' population density was observed in May and the lowest one was observed in February and November. These results demonstrate the existence of a high diversity of anophelines in the study areas, showing that anthropic changes in the environment and climate variability affect both the population density and relative abundance of these vectors.

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Thermoplastic elastomers based on a triblock copolymer styrene-butadiene-styrene (SBS) with different butadiene/styrene ratios, block structure and carbon nanotube (CNT) content were submitted to accelerated weathering in a Xenontest set up, in order to evaluate their stability to UV ageing. It was concluded that ageing mainly depends on butadiene/styrene ratio and block structure, with radial block structures exhibiting a faster ageing than linear block structures. Moreover, the presence of carbon nanotubes in the SBS copolymer slows down the ageing of the copolymer. The evaluation of the influence of ageing on the mechanical and electrical properties demonstrates that the mechanical degradation is higher for the C401 sample, which is the SBS sample with the largest butadiene content and a radial block structure. On the other hand, a copolymer derivate from SBS, the styrene-ethylene/butadiene-styrene (SEBS) sample, retains a maximum deformation of ~1000% after 80 h of accelerated ageing. The hydrophobicity of the samples decreases with increasing ageing time, the effect being larger for the samples with higher butadiene content. It is also verified that cytotoxicity increases with increasing UV ageing with the exception of SEBS, which remains not cytotoxic up to 80 h of accelerated ageing time, demonstrating its potential for applications involving exposition to environmental conditions.

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The Cutia-nut (Couepia edulis Prance), a species originally from the Amazon region, has a kernel with reasonable nutritional value and a hard and thick woody shell that constitute most of the fruit. After the kernel removal, the shells are regarded as waste. The possibility of using such shells, as raw material for burning or charcoal production, as well as milled residue for structural reinforcement materials is quite feasible, considering environmental and economical aspects. There is, however, a complete lack of characterization of the Cutia-nut shell and other similar species which can aggregate desirable qualities for application as engineering material. In this study some analyses are presented aiming at providing information for potential uses of these residues. In general, the shells follow a regular shape with certain dimensional proportionality to the kernel. The shell is a fibrous material with high lignin content, present low water absorption and high resistance to natural degradation.

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The exceptional properties of localised surface plasmons (LSPs), such as local field enhancement and confinement effects, resonant behavior, make them ideal candidates to control the emission of luminescent nanoparticles. In the present work, we investigated the LSP effect on the steady-state and time-resolved emission properties of quantum dots (QDs) by organizing the dots into self-assembled dendrite structures deposited on plasmonic nanostructures. Self-assembled structures consisting of water-soluble CdTe mono-size QDs, were developed on the surface of co-sputtered TiO2 thin films doped with Au nanoparticles (NPs) annealed at different temperatures. Their steady-state fluorescence properties were probed by scanning the spatially resolved emission spectra and the energy transfer processes were investigated by the fluorescence lifetime imaging (FLIM) microscopy. Our results indicate that a resonant coupling between excitons confined in QDs and LSPs in Au NPs located beneath the self-assembled structure indeed takes place and results in (i) a shift of the ground state luminescence towards higher energies and onset of emission from excited states in QDs, and (ii) a decrease of the ground state exciton lifetime (fluorescence quenching).

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Este relatório segue a metodologia utilizada no estudo da produção científica da Universidade do Minho do quinquénio 2008-2012. No estudo da produção de 2009-2013, para além da análise dos dados indexados na Web of Science, optou-se por acrescentar a análise dos dados indexados na Scopus, procedendo-se à comparação dos resultados entre ambas as bases de dados sempre que adequado e possível.

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Pedro Andrade destaca o papel que as literacias híbridas preenchem numa redefinição pós-colonial da Europa. Em sua opinião, as literacias híbridas constituem uma condição necessária para a desconstrução do discurso colonial e a posterior reconstrução de literacias e literaturas pós-coloniais. Como parte deste processo, o autor argumenta a necessidade de vários tipos de competências que enfatizem a leitura e escrita não apenas dentro de sua própria cultura, mas também nas culturas dos outros. A literacia digital desempenha um papel particularmente importante neste processo, o que nos permite enfatizar as multivocalidades desta alteridade, igualmente na interação entre diferentes tradições de literacia: Ocidental e Oriental, nacional e transnacional, verbal e mediática. Andrade exemplifica o conceito de literatura transmediática com uma série de projetos em que esteve envolvido, por exemplo a Web 3.0 Novel enquanto modalidade daquilo que ele nomeia "GeoNeoLogic Novel". Este género de novel experimental mistura a narrativa com a teoria e a recolha de dados no campo empírico, promovendo uma abordagem que se apresenta simultaneamente regional e global. Em suma, o autor sugere diversos conceitos em primeira mão que classifica de ‘origem Lusófona’, e que representam diversas estratégias pós-coloniais globais também visíveis na área social, política e cultural da Lusofonia: o ‘pensamento-réplica’ (thinking back); o 'conhecimento transmediático' (transmediatic knowledge); a ‘sociedade da escrita comum’ (common writing society); as ‘redes comuns de conflito/significado’ (common webs of conflict and meaning); a literatura co-ordinária (co-ordinary literature).

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Construction of hydroelectric dams in tropical regions has been contributing significantly to forest fragmentation. Alterations at edges of forest fragments impact plant communities that suffer increases in tree damage and dead, and decreases in seedling recruitment. This study aimed to test the core-area model in a fragmented landscape caused by construction of a hydroelectric power plant in the Brazilian Amazon. We studied variations in forest structure between the margin and interiors of 17 islands of 8-100 hectares in the Tucuruí dam reservoir, in two plots (30 and >100m from the margin) per island. Mean tree density, basal area, seedling density and forest cover did not significantly differ between marginal and interior island plots. Also, no significant differences were found in liana density, dead tree or damage for margin and interior plots. The peculiar topographic conditions associated with the matrix habitat and shapes of the island seem to extend edge effects to the islands' centers independently of the island size, giving the interior similar physical microclimatic conditions as at the edges. We propose a protocol for assessing the ecological impacts of edge effects in fragments of natural habitat surrounded by induced (artificial) edges. The protocol involves three steps: (1) identification of focal taxa of particular conservation or management interest, (2) measurement of an "edge function" that describes the response of these taxa to induced edges, and (3) use of a "Core-Area Model" to extrapolate edge function parameters to existing or novel situations.

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This study used event-related potentials to examine interactions between mood, sentence context, and semantic memory structure in schizophrenia. Seventeen male chronic schizophrenia and 15 healthy control subjects read sentence pairs after positive, negative, or neutral mood induction. Sentences ended with expected words (EW), within-category violations (WCV), or between-category violations (BCV). Across all moods, patients showed sensitivity to context indexed by reduced N400 to EW relative to both WCV and BCV. However, they did not show sensitivity to the semantic memory structure. N400 abnormalities were particularly enhanced under a negative mood in schizophrenia. These findings suggest abnormal interactions between mood, context processing, and connections within semantic memory in schizophrenia, and a specific role of negative mood in modulating semantic processes in this disease.

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Dissertação de mestrado em Engenharia Mecânica

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Dissertação de mestrado em Structural Analysis of Monuments and Historical Constructions

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[Excerpt] The idea of community is usually associated with radio today in the context of what Bart Cammaerts (2009,635) classifies as a "third type of broadcast, namely participatory radio, complementary to both commercial and public media". Following Ellie Rennie (2006, 3), community radio corresponds, as all other forms of community media, to non-profit media that provide "community members with an opportunity to participate in the production process". For the International Association for Media and Communication Research, which supports a research group on Community Communication, this area includes media that originate from, circulate and resonate with the sphere of civil society.

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[Excerto] Desenvolvendo alguns dos pressupostos de McLuhan (1994), criou-se, não há muito tempo, uma disciplina a que se deu o nome de Mediologia (Debray, 2000). Nessa perspectiva, os media são as maneiras pelas quais sabemos, pelas quais pensamos, pelas quais criamos ummundo, namedida em que pensamos e vivemos cada vez mais com os media. É a implicação entre comunicação e complexidade que tece esta infra-estruturamediática: a comunicação está permanentemente a gerar comunicação. O trabalho sobre a comunicação, quer nos seus aspectos imediatamente tecnológicos (como as tecnologias do ecrã), quer nos domínios sociais e íntimos que a comunicação atinge, vem complexificar ainda mais as sociedades — vem exigir ainda mais comunicação.