1,460 research outputs found

    The development of an assimilative capacity model for the sustainable management of nutrients within the Ria Formosa in southern Portugal

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    Mathematical modelling approaches have been widely used to evaluate the capacity of an ecosystem to assimilate anthropogenic wastes. This is essential to develop sustainable management strategies and for the prevention of eutrophication. This project aimed to assess the importance of the benthic-pelagic interactions in Ria Formosa and to develop a simple biogeochemical model for the management of nutrient inputs. This was done by adapting the simple version of the CSTT model, for pelagic eutrophication, to the system and by adding a benthic primary producer, the microphytobenthos (MPB), which was previously indicated as one of the main components of the system. This research project has three main parts: 1) field work that provided context and data for model testing; 2) experimental work, which aimed at evaluating key parameters of the system to be used in the modelling approach; 3) model development work that was used to test hypotheses and provided a synthesis of ecological achievements. An initial assessment of the optimal methodology for MPB chlorophyll extraction was carried out to implement a strategy for an accurate chlorophyll measurement. The MPB temporal, spatial and vertical variability was investigated. The complex temporal pattern revealed a small influence of seasonality. However, phytoplankton was found to have a much more important seasonal component. The most important component of the MPB variability was found to be the small and large scale spatial variability, which explains around 61% of the total variance. MPB was also found to be the most important source of chlorophyll to the lagoon system, contributing around 99% of the total chlorophyll. The experimental approach carried out to investigate the yield of MPB chlorophyll from nutrients, which was previously considered to be one of the most important parameters of the CSTT model for phytoplankton, revealed interesting results. Estimates were found to be larger than the values used for phytoplankton. The development process of the biogeochemical dCSTT-MPB model allowed the investigation of the importance of several processes. Pore water nutrients were found to be essential to support the large MPB community. Moreover, MPB cells were also found to have a large impact on the pelagic chlorophyll concentrations by re-suspension. The model was able to predict concentrations in the appropriate range of values observed in the lagoon. However, the temporal pattern is still weakly simulated and improvements are still required.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    Disentangling Environmental Drivers of Phytoplankton Biomass off Western Iberia

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    Phytoplankton are the main primary producers in marine ecosystems, supporting important food webs. They are recognized as important indicators of environmental changes in oceans and coastal waters. Ocean color remote sensing has been extensively used to study phytoplankton (i.e., chlorophyll a – CHL – as a proxy of phytoplankton biomass) throughout the world, yet there is still much to understand in terms of what influences phytoplankton communities at regional scales. The main aim of this study was to investigate the drivers of CHL variability in the Western Iberian Coast (WIC), for the period 1998–2016. Satellite CHL data were acquired from the Copernicus Marine Environment Monitoring Service. A positive annual trend of CHL was observed at the Northern coastal WIC, near Galicia, and a negative trend was observed in Southern areas, near the Gulf of Cádiz. An empirical orthogonal function analysis was implemented to identify regions with similar patterns of CHL variability. Six regions were obtained. A set of climate indices, satellite, and model variables were then used as environmental predictors in generalized additive models that explained between 22.8 and 52.8% of the total variance of CHL anomalies calculated from a detrended and deseasoned dataset. In the Northern oceanic region, positive anomalies were linked to high North Atlantic Oscillation values and negative anomalies to high mixed layer depths. In the Southern oceanic region, positive CHL anomalies were found to be associated with high concentrations of nitrogen, that may indicate nitrogen limitation. CHL in coastal areas were found to respond to basin-wide (e.g., Atlantic Multidecadal Oscillation) and coastal processes (e.g., upwelling and continental runoff), yielding positive anomalies with low salinity (SAL) values. In coastal areas off major rivers, such as Douro and Guadalquivir, the positive response of CHL to increased nitrogen concentrations and decreased SAL was evident. Considering the changes in climate expected for this region, related to the decrease in precipitation and increase in summer temperatures, as well as some apparent weakening of upwelling, possible significant impacts on the phytoplankton community can be anticipated. These results are therefore also relevant for environmental management, especially in the context of the European Marine Strategy Framework Directive

    Cognitive performance in childhood: mother and urban environment make the difference

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    Apesar das controvérsias sobre o conceito e a avaliação da inteligência, o desempenho cognitivo assume um papel fundamental no contexto educativo e são múltiplos os fatores que lhe estão associados. Este estudo toma uma amostra aleatória e representativa de 1201 crianças do 2.º ciclo do ensino básico de escolas públicas portuguesas, com idades entre 9 e 14 anos. Discute-se o impacto das variáveis sociofamiliares (profissão da mãe e do pai, escolaridade da mãe e do pai e meio de pertença urbano vs rural). Os resultados destacam a relevância dessas variáveis para a explicação do desempenho cognitivo dos alunos, especialmente a escolaridade da mãe e o meio urbano de proveniência. Apresentam-se considerações práticas voltadas à equidade do sistema educativo.Despite the controversies over the concept and evaluation of intelligence, cognitive achievement plays a fundamental role in educational context, and multiple factors are related to it. The current study uses a random and representative sample of 1201 2nd grade children from Portuguese public schools, between 9 and 14 years old. This study aims to discuss the impact of social and familial variables (mother and father’s jobs, mother and father’s educational level, and urban or rural environment of belonging). The results highlight the importance of social and familial variables as an explanation to students’ cognitive achievement, with great relevance to mother’s educational level and urban environment of belonging. Practical considerations aiming a better equity in educational system are presented.info:eu-repo/semantics/publishedVersio

    A case study of ergonomics encompassing white-collar workers: anthropometry, furniture dimensions, working posture and musculoskeletal disorders

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    Regardless of their specific business, white collar workers have some factors in common: they work seated without moving for a long time, they use certain arm and hand muscles excessively, and they tend to keep a poor body posture. The resulting Musculoskeletal Disorders (MSDs) produce discomfort, and even pain. This study aimed at an ergonomic assessment of white collars of a Portuguese company – to identify the most critical points in old furniture designs and working posture habits. An evaluation was done in the administrative department using a random sample; the anthropometric and furniture measurements were taken and compared. The RULA method was used to evaluate the risk arising from adoption of a poor posture at the workplace. The results obtained show a prevalence of symptoms of MSDs. The furniture is oversized in most cases. Adoption of a poor posture at the workplace requires a short-term intervention. There is a significant association between MSDs and wrong-dimensioned furniture, besides habit to adopt wrong postures. This company (as many other SME’s) must change the old style office furniture by one with dimensions matching workers’ anthropometry, and provide training on best practices to maintain good posture at workinfo:eu-repo/semantics/publishedVersio

    The development of an assimilative capacity model for the sustainable management of nutrients within the Ria Formosa in southern Portugal

    Get PDF
    Mathematical modelling approaches have been widely used to evaluate the capacity of an ecosystem to assimilate anthropogenic wastes. This is essential to develop sustainable management strategies and for the prevention of eutrophication. This project aimed to assess the importance of the benthic-pelagic interactions in Ria Formosa and to develop a simple biogeochemical model for the management of nutrient inputs. This was done by adapting the simple version of the CSTT model, for pelagic eutrophication, to the system and by adding a benthic primary producer, the microphytobenthos (MPB), which was previously indicated as one of the main components of the system.This research project has three main parts: 1) field work that provided context and data for model testing; 2) experimental work, which aimed at evaluating key parameters of the system to be used in the modelling approach; 3) model development work that was used to test hypotheses and provided a synthesis of ecological achievements.An initial assessment of the optimal methodology for MPB chlorophyll extraction was carried out to implement a strategy for an accurate chlorophyll measurement. The MPB temporal, spatial and vertical variability was investigated. The complex temporal pattern revealed a small influence of seasonality. However, phytoplankton was found to have a much more important seasonal component. The most important component of the MPB variability was found to be the small and large scale spatial variability, which explains around 61% of the total variance. MPB was also found to be the most important source of chlorophyll to the lagoon system, contributing around 99% of the total chlorophyll. The experimental approach carried out to investigate the yield of MPB chlorophyll from nutrients, which was previously considered to be one of the most important parameters of the CSTT model for phytoplankton, revealed interesting results. Estimates were found to be larger than the values used for phytoplankton.The development process of the biogeochemical dCSTT-MPB model allowed the investigation of the importance of several processes. Pore water nutrients were found to be essential to support the large MPB community. Moreover, MPB cells were also found to have a large impact on the pelagic chlorophyll concentrations by re-suspension. The model was able to predict concentrations in the appropriate range of values observed in the lagoon. However, the temporal pattern is still weakly simulated and improvements are still required

    Exploratory study on maturation and competition level in young karate practitioners

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    Emparelhar crianças propicia sucesso e reduz lesões no desporto. Apesar das diferenças de maturação entre crianças, a idade cronológica mantém-se o principal critério para equalizar os níveis de competição, mas com uma eficiência limitada. No entanto, no karaté, o peso também é considerado. Fomos verificar se existe associação entre a idade cronológica e os indicadores maturacionais e, encontrar modelos simples que permitam colocar em reflexão novas formas de avaliação da maturação. Foram recolhidos dados em 54 jovens praticantes de karaté (idade: 12,67 ± 2,49 anos; experiência: 4,99 ± 2,44 anos; altura: 150,45 ± 15,25cm; peso: 43,09 ± 14,17 kg, 20 raparigas). A idade correlacionou-se significativamente com auto-observação da maturação sexual (rho = 0,838; p < 0,01), e foi possível encontrar modelos de regressão simples que têm uma explicação moderada na maturação, apenas utilizando variáveis de medição simples, tal como a altura, o peso e o perímetro do braço. Estes resultados devem levar as entidades competentes a refletir acerca do modo de emparelhamento dos atletas nas competições de uma forma justa em termos de maturação.Paring children improve the chance for success and reduce injury in sport. Despite the maturity differences between children, chronological age remains the main criterion to equalize competition levels, but with limited efficiency. However, in Karate, weight is also considered. We went to investigate the association between chronological age and maturational indicators and find simple models to put on reflection new ways to assess the maturity. Data were collected in 54 young Karate practitioners (age: 12.67 ± 2.49 years, experience: 4.99 ± 2.44 years, height: 150.45 ± 15.25 cm, weight: 43.09 ± 14, 17 kg, 20 girls). Age correlated significantly with self-observation of sexual maturation (rho = 0.838; p < 0.01), and it was possible to find simple regression models that have a moderate explanation in maturation, using only simple measurable variables such as the height, weight and arm circumference. These results should lead the competent entities to reflect on the way of pairing of the athletes in the competitions, in a fair way in terms of maturation.info:eu-repo/semantics/publishedVersio

    Comparing reverse complementary genomic words based on their distance distributions and frequencies

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    In this work we study reverse complementary genomic word pairs in the human DNA, by comparing both the distance distribution and the frequency of a word to those of its reverse complement. Several measures of dissimilarity between distance distributions are considered, and it is found that the peak dissimilarity works best in this setting. We report the existence of reverse complementary word pairs with very dissimilar distance distributions, as well as word pairs with very similar distance distributions even when both distributions are irregular and contain strong peaks. The association between distribution dissimilarity and frequency discrepancy is explored also, and it is speculated that symmetric pairs combining low and high values of each measure may uncover features of interest. Taken together, our results suggest that some asymmetries in the human genome go far beyond Chargaff's rules. This study uses both the complete human genome and its repeat-masked version.Comment: Post-print of a paper accepted to publication in "Interdisciplinary Sciences: Computational Life Sciences" (ISSN: 1913-2751, ESSN: 1867-1462

    Effects of climate change on aquaculture site selection at a temperate estuarine system

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    Aquaculture is one of the food industries that most evolved in recent years in response to increased human demand for seafood products, which has led to a progressive stock threat in nature. With a high seafood consumption per capita, Portugal has been exploring its coastal systems to improve the cultivation of fish and bivalve species with high commercial value. In this context, this study aims to propose the use of a numerical model as a tool to assess the impact of climate change on aquaculture site selection in a temperate estuarine system (Sado estuary). Therefore, the Delft3D model was calibrated and validated, showing good accuracy in predicting the local hydrodynamics, transport, and water quality. Furthermore, two simulations for the historical and future conditions were performed to establish a Suitability Index capable of identifying the most appropriate sites to exploit two bivalve species (one clam and one oyster), considering both winter and summer seasons. Results suggest that the estuary's northernmost region presents the best conditions for bivalves' exploitation, with more suitable conditions during summer than winter due to the higher water temperature and chlorophyll-a concentrations. Regarding future projections, the model results suggest that environmental conditions will likely benefit the production of both species due to the increase in chlorophyll-a concentration along the estuary.publishe

    Dissimilar Symmetric Word Pairs in the Human Genome

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    In this work we explore the dissimilarity between symmetric word pairs, by comparing the inter-word distance distribution of a word to that of its reversed complement. We propose a new measure of dissimilarity between such distributions. Since symmetric pairs with different patterns could point to evolutionary features, we search for the pairs with the most dissimilar behaviour. We focus our study on the complete human genome and its repeat-masked version.Comment: Submitted 13-Feb-2017; accepted, after a minor revision, 17-Mar-2017; 11th International Conference on Practical Applications of Computational Biology & Bioinformatics, PACBB 2017, Porto, Portugal, 21-23 June, 201
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