Browsing by Issue Date, starting with "2014-10"
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- Do personality differences between students from different schools generalize across countries?Publication . Costa, Patricio; Costa, Manuel João; Neto, Isabel; Marvão, Pedro; Portela, Miguel
- Trap modification opens new gates to achieve sustainable coral reef fisheriesPublication . Gomes, Ines; Erzini, Karim; McClanahan, Timothy R.Innovative strategies are needed to escape the social-ecological poverty that so frequently emerges from persistent overfishing of coral reef resources.This study focuses on fishing gear selectivity and its potential to increase ecosystem health and fisheries productivity without compromising the catch of profitable species.An investigation into the effects of an escape gap (3cm x 30cm) modification to the traditional African basket trap on total catch biomass, catch composition and monetary value in two locations with different historical levels of fishing was undertaken.Gated traps caught less low-value fish (juveniles and narrow-bodied coral reef species) while increasing the catch of high- and medium-value fish (wider-bodied commercially valuable species). The total monetary value of the gated trap catches was maintained in a heavily fished environment, while it increased in the less fisheries-depleted area.For the most important local commercial species, the African white-spotted rabbitfish (Siganus sutor), the gated traps significantly increased the mean length (by 12%) and weight (by 32%) of capture and decreased the proportion of catch under length at first maturity (Lmat) from 56% (traditional traps) to 25% (gated traps).Escape gaps have shown the potential to affect the structure of the fishery and ecosystem by enhancing the number of mature individuals, increasing reef biodiversity and promoting functionally diverse reef fish communities without compromising fisher's revenues. Copyright (c) 2013 John Wiley & Sons, Ltd.
- Gillnet selectivity for freshwater fish species in three lentic systems of GreecePublication . Petriki, O.; Erzini, Karim; Moutopoulos, D. K.; Bobori, D. C.Gillnet size selectivity was studied for freshwater fish species, based on experimental fishing trials carried out with multimesh gillnets in lentic freshwater systems in Northern Greece. Selectivity estimates were based on a large range of mesh sizes, i.e. more than 10 different mesh sizes ranging from 8 to 90 mm bar length. Results showed that the model, in which both mean and standard deviation of the curve were defined as a linear function of the mesh size, revealed the best fit. For seven (i.e. Alburnus sp. Volvi, Aspius aspius, Carassius gibelio, Lepomis gibbosus, Pachychilon macedonicum, Squalius prespensis and Vimba melanops) of the 11 studied species and the hybrid (Alburnus belvica x Rutilus prespensis), gillnet selectivity parameters were estimated for the first time, contributing to the evaluation of gillnet fisheries' impacts on fish species populations and consequently to fisheries management and species conservation.
- Exposição à radiação secundária na realização de estudos radiológicos a pacientes intransportáveisPublication . Abrantes, António; Sousa, Patrick; Ribeiro, Luís; Rodrigues, Sónia Isabel do Espírito Santo; Rebelo, Carina; Azevedo, Kevin; Almeida, Rui; Pinheiro, JoãoObjetivo: Considerando que numa unidade hospitalar existem serviços onde estão internados pacientes que não se podem deslocar, sendo-lhes frequentemente prescritos estudos radiológicos, o objetivo deste trabalho consistiu em quantificar a exposição à radiação secundária na realização de radiogramas a doentes intransportáveis. Desta forma, pretendeu-se compreender, de acordo com a legislação em vigor e o state-of-art, que medidas devem ser adotadas/corrigidas no sentido de proteger adequadamente os profissionais, os pacientes que se submetem ao exame e também aqueles que inevitavelmente têm de permanecer na sala onde é realizado o exame. Metodologia: Foi efetuado o levantamento das condições técnicas utilizadas no exame em doentes intransportáveis numa amostra de 199 exames, o que possibilitou a determinação dos parâmetros de referência. Estes parâmetros foram também utilizados no controlo de qualidade do equipamento móvel de Radiologia Convencional, efetuado com um detetor semicondutor. Posteriormente, e uma vez que a radiologia utiliza radiação ionizante, o que condiciona todo e qualquer estudo experimental no ser humano, procedemos à simulação, e medição da radiação dispersa, reproduzindo as condições registadas no levantamento prévio, para a incidência ântero-posterior do tórax e para a incidência tangencial do abdómen (por serem as mais realizadas), com um fantôma antropomórfico de corpo inteiro em decúbito dorsal e semi-sentado. Mediu-se a radiação dispersa em função da voltagem e do produto corrente-tempo com um dosímetro de radiação X e gama. Fixando esses parâmetros, mediu-se a radiação dispersa em função do ângulo, altura e distância do dosímetro, para as incidências do tórax. A variação da radiação dispersa em função do ângulo foi também medida para a incidência do abdómen. Resultados: Para distâncias inferiores a 1 m, o Limite de dose estabelecido pela legislação para os trabalhadores expostos não é ultrapassado (12 mSv/ano) mas para os membros do público já será (2 mSv/ano). Os trabalhadores expostos devem utilizar dosímetro individual e no alcance do feixe primário devem usar medidas de proteção e posicionar-se atrás da ampola do equipamento móvel. De acordo com as três configurações utilizadas, resultantes do levantamento das características do feixe conjugadas com a tipologia de exames mais solicitados, obtivemos curvas de isodose que nos permitem determinar as distância e localização mais seguras, bem como, determinar o tipo de proteção radiológica que devemos utilizar nos indivíduos expostos. Conclusão: É fundamental utilizar medidas de proteção radiológicas para não ultrapassar os limites de dose e cumprir com o princípio ALARA, para melhor proteger os profissionais, os pacientes e o público em geral, entenda-se, outros pacientes que inevitavelmente têm de permanecer no mesmo espaço.
- Verificação experimental do nível de precisão do método dos elementos de fibras de contactoPublication . Estêvão, João Manuel Carvalho; Carreira, A. S.A obtenção de soluções analíticas de sistemas dinâmicos com distribuição contínua da massa apresenta uma elevada complexidade. Os problemas práticos envolvem, normalmente, um processo de discretização com maior ou menor número de graus de liberdade. Nestes problemas discretos, a massa do sistema dinâmico é concentrada num número finito de nós. Contudo, este processo de discretização origina soluções que correspondem somente a uma aproximação da solução exata, pois a massa está distribuída de uma forma contínua. O número mínimo de graus de liberdade a considerar na resolução deste tipo de problemas depende muito da sua natureza, e do método adotado para a análise da estrutura. O método dos elementos de fibras de contacto (MEFC) é um novo método de análise de estruturas, que pode ser usado na análise dinâmica de sistemas dinâmicos contínuos, pois recorre a micromodelos das estruturas. Para melhor entendermos a capacidade deste novo método nos resultados da análise dinâmica de uma estrutura, foi realizada uma comparação entre os valores obtidos via experimental e os obtidos pelo MEFC. Os resultados obtidos parecem indicar que este novo método pode conduzir a valores muito próximos dos obtidos por via experimental.
- Environmental and fishery-driven dynamics of the common octopus (Octopus vulgaris) based on time-series analyses from leeward Algarve, southern PortugalPublication . Sonderblohm, Carlos; Pereira, João; Erzini, KarimDynamic factor analysis was used to explore monthly landings per unit effort (LPUE) series of Octopus vulgaris and environmental variables recorded in the southwest Iberian Peninsula, south Portugal. Despite the large fluctuations in the octopus abundance series, results showed a strong aggregation pattern for the last 3 months of the year, possibly related to the input of new recruits to the fishery. The calculated common trend for the 12 months time-series presented significant correlations with autumn rainfall of the previous year (lag - 1), particularly for the October, November, and December series. Other important correlations were found for the Western Mediterranean Oscillation index (lag - 1), Ekman transport, summer river run-off (lag - 1), horizontal and vertical component of windstress, among others. The main trend describes a moderate steady increase in LPUE during the last 10 years, suggesting that octopus abundance has increased from 1990 to 2010. The strong correlations of the monthly octopus LPUE series, together with the annual life cycle, suggest that after environmentally controlled recruitment, population dynamics is largely fishery driven, resulting in strong seasonality in the landings.
- Framework for the characterization of hotel websitesPublication . Correia, Marisol B.; Ramos, Célia M. Q.; Rodrigues, J. M. F.; Cardoso, Pedro J. S.Nowadays the importance of websites to the tourism and hospitality industries is fundamental. Hotels, for instance, spend a huge amount of money improving their websites to show all the activities and amenities that they can provide. There are studies to evaluate website performance based on functionality, usability and other factors; nevertheless, they are not exhaustive. This paper presents a framework for the characterization of hotel and resort websites, that was applied as a case study to the websites of 5-star hotels and resorts that operate in the tourism region of the Algarve, Portugal. This framework allows us to identify a set of features for the hotel and resort websites characterization. From these features, we propose a set of comprehensive indicators, grouping them into ten fundamental information dimensions, as well as the application of these indicators and information dimensions, which allows obtaining quantitative and qualitative results.
- Immunocytotoxicity, cytogenotoxicity and genotoxicity of cadmium-based quantum dots in the marine mussel Mytilus galloprovincialisPublication . Lopes Rocha, Thiago; Gomes, Tânia; Cardoso, Cátia; Letendre, Julie; Pinheiro, José Paulo; Serrão Sousa, Vânia; Ribau Teixeira, Margarida; Bebianno, MariaThere is an increased use of Quantum Dot (QDs) in biological and biomedical applications, but little is known about their marine ecotoxicology. So, the aim of this study was to investigate the possible immunocytotoxic, cytogenotoxic and genotoxic effects of cadmium telluride QDs (CdTe QDs) on the marine mussel Mytilus galloprovincialis. Mussels were exposed to 10 μg L(-1) of CdTe QDs or to soluble Cd [Cd(NO3)2] for 14 days and Cd accumulation, immunocytotoxicity [hemocyte density, cell viability, lysosomal membrane stability (LMS), differential cell counts (DCC)], cytogenotoxicity (micronucleus test and nuclear abnormalities assay) and genotoxicity (comet assay) were analyzed. Results show that in vivo exposure to QDs, Cd is accumulated in mussel soft tissues and hemolymph and induce immunotoxic effects mediated by a decrease in LMS, changes in DCC, as well as genotoxicity (DNA damage). However, QDs do not induce significant changes in hemocytes density, cell viability and cytogenetic parameters in opposition to Cd(2+). Soluble Cd is the most cytotoxic and cytogenotoxic form on Mytilus hemocytes due to a higher accumulation of Cd in tissues. Results indicate that immunotoxicity and genotoxicity of CdTe QDs and Cd(2+) are mediated by different modes of action and show that Mytilus hemocytes are important targets for in vivo QDs toxicity.
- Nitric oxide from inflammatory origin impairs neural stem cell proliferation by inhibiting epidermal growth factor receptor signalingPublication . Carreira, Bruno P.; Morte, Maria I.; Santos, Ana I.; Lourenco, Ana S.; Ambrosio, Antonio F.; Carvalho, Caetana M.; Araújo, InêsNeuroinflammation is characterized by activation of microglial cells, followed by production of nitric oxide (NO), which may have different outcomes on neurogenesis, favoring or inhibiting this process. In the present study, we investigated how the inflammatory mediator NO can affect proliferation of neural stem cells (NSCs), and explored possible mechanisms underlying this effect. We investigated which mechanisms are involved in the regulation of NSC proliferation following treatment with an inflammatory stimulus (lipopolysaccharide plus IFN-gamma), using a culture system of subventricular zone (SVZ)-derived NSCs mixed with microglia cells obtained from wild-type mice (iNOS(+/+)) or from iNOS knockout mice (iNOS(-/-)). We found an impairment of NSC cell proliferation in iNOS(+/+) mixed cultures, which was not observed in iNOS(-/-) mixed cultures. Furthermore, the increased release of NO by activated iNOS(+/+) microglial cells decreased the activation of the ERK/MAPK signaling pathway, which was concomitant with an enhanced nitration of the EGF receptor. Preventing nitrogen reactive species formation with MnTBAP, a scavenger of peroxynitrite (ONOO-), or using the ONOO- degradation catalyst FeTMPyP cell proliferation and ERK signaling were restored to basal levels in iNOS(+/+) mixed cultures. Moreover, exposure to the NO donor NOC-18 (100 mu M), for 48 h, inhibited SVZ-derived NSC proliferation. Regarding the antiproliferative effect of NO, we found that NOC-18 caused the impairment of signaling through the ERK/MAPK pathway, which may be related to increased nitration of the EGF receptor in NSC. Using MnTBAP nitration was prevented, maintaining ERK signaling, rescuing NSC proliferation. We show that NO from inflammatory origin leads to a decreased function of the EGF receptor, which compromised proliferation of NSC. We also demonstrated that NO-mediated nitration of the EGF receptor caused a decrease in its phosphorylation, thus preventing regular proliferation signaling through the ERK/MAPK pathway.
- Thermal adaptation and clinal mitochondrial DNA variation of European anchovyPublication . Silva, Goncalo; Lima, Fernando P.; Martel, Paulo; Castilho, RitaNatural populations of widely distributed organisms often exhibit genetic clinal variation over their geographical ranges. The European anchovy, Engraulis encrasicolus, illustrates this by displaying a two-clade mitochondrial structure clinally arranged along the eastern Atlantic. One clade has low frequencies at higher latitudes, whereas the other has an anti-tropical distribution, with frequencies decreasing towards the tropics. The distribution pattern of these clades has been explained as a consequence of secondary contact after an ancient geographical isolation. However, it is not unlikely that selection acts on mitochondria whose genes are involved in relevant oxidative phosphorylation processes. In this study, we performed selection tests on a fragment of 1044 bp of the mitochondrial cytochrome b gene using 455 individuals from 18 locations. We also tested correlations of six environmental features: temperature, salinity, apparent oxygen utilization and nutrient concentrations of phosphate, nitrate and silicate, on a compilation of mitochondrial clade frequencies from 66 sampling sites comprising 2776 specimens from previously published studies. Positive selection in a single codon was detected predominantly (99%) in the anti-tropical clade and temperature was the most relevant environmental predictor, contributing with 59% of the variance in the geographical distribution of clade frequencies. These findings strongly suggest that temperature is shaping the contemporary distribution of mitochondrial DNA clade frequencies in the European anchovy.