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Esteban-Millat I.,University for Business Studies | Martinez-Lopez F.J.,University of Granada | Huertas-Garcia R.,Av. Diagonal | Meseguer A.,University for Business Studies | Rodriguez-Ardura I.,University for Business Studies
Computers and Education | Year: 2014

This paper aims to clarify and characterize the role of flow in student's behavioural processes in virtual learning environments. To this end, an integral model of flow in e-learning environments is proposed and tested. The empirical part of the research was based on both qualitative and quantitative techniques. The former consisted of seven in-depth interviews carried out with experts in e-learning environments and two different groups. The latter consisted of an online survey resulting in a sample of 2574 valid questionnaires. The theoretical model was tested and validated using the standard methodological procedure based on exploratory and confirmatory analyses. The results indicate that time distortions and focused attention are the most important direct antecedents of flow. The challenges posed by the environment were revealed as the main indirect conditioner of the experience, but other factors, such as personalization (a new variable not considered in previous flow studies in the e-learning context), were also found to be significant. In short, this papers sheds light on the processes of online browsing and, thus, on a more suitable design for an e-learning environment. Furthermore, two direct positive consequences of the flow experience are proved: positive affect (such as feeling happy, satisfied and cheerful) and student learning. In sum, it can be concluded that institutions are better off providing students with e-learning environments conducive to getting them into a flow state. © 2013 Elsevier Ltd. All rights reserved. Source


Acosta R.,University of Barcelona | Prat N.,Av. Diagonal
Fundamental and Applied Limnology | Year: 2010

The diversity of genera and species of the family Chironomidae in the Andean region, as well as their variation with season and altitude, are scarcely known. Here, a semi-quantitative sampling was conducted at 35 stations with little or no human disturbance in the basin of the Cañete River (Peru), situated on the western slope of the Andes, between 2553 and 4396 m a.s.l. during the dry (2004) and rainy (2005) season. A total of 38 genera of Chironomidae were found, of which 21 belong to the subfamily Orthocladiinae. No significant differences in richness of genera were found among the four different altitudinal ranges surveyed. A greater richness of genera was found during the rainy season. Most of the genera were distributed across the entire altitudinal gradient studied, especially species of the genus Cricotopus. Only Podonomopsis and Limnophyes showed evident preference for altitude range 4 (4000-4500 m a.s.l.), Podonomus for altitude range 3 (3500-4000 m a.s.l.), and Rheotanytarsus for altitude range 1 (2500-3000 m a.s.l.). The presence of many undetermined genera, especially Orthocladiinae, as well as the estimates indicated by the species accumulation curves, suggest that the real diversity of genera of Chironomidae in the Andean region is still far from being known. © 2010 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany. Source


Becker P.H.,Institute of Avian Research Vogelwarte Helgoland | Goutner V.,Aristotle University of Thessaloniki | Ryan P.G.,University of Cape Town | Gonzalez-Solis J.,Av. Diagonal
Environmental Pollution | Year: 2016

We studied mercury contamination in 25 seabird species breeding along a latitudinal gradient across the Southern Ocean, from Gough Island (40°S) through Marion Island (47°S) to Byers Peninsula (63°S). Total mercury concentrations in body feather samples of adults caught at breeding colonies from 2008 to 2011 were determined. Krill (Euphausia spp.) and other zooplankton consumers had low mercury concentrations (gentoo penguin Pygoscelis papua, chinstrap penguin Pseudomonas Antarctica, common diving petrel Pelecanoides urinatrix, broad-billed prion Pachyptila vittata; mean levels 308-753 ng g-1), whereas seabirds consuming squid or carrion had high mercury concentrations (ascending order: Kerguelen petrel Aphrodroma brevirostris, southern giant petrel Macronectes giganteus, soft-plumaged petrel Pterodroma mollis, sooty albatross Phoebetria fusca, Atlantic petrel Pterodroma incerta, northern giant petrel Macronectes halli, great-winged petrel Pterodroma macroptera; 10,720-28038 ng g-1). The two species with the highest mercury concentrations, northern giant petrels and great-winged petrels, bred at Marion Island. Among species investigated at multiple sites, southern giant petrels had higher mercury levels at Marion than at Gough Island and Byers Peninsula. Mercury levels among Byers Peninsula seabirds were low, in two species even lower than levels measured 10 years before at Bird Island, South Georgia. Replicate measurements after about 25 years at Gough Island showed much higher mercury levels in feathers of sooty albatrosses (by 187%), soft-plumaged petrels (53%) and Atlantic petrels (49%). Concentrations similar to the past were detected in southern giant petrels at Gough and Marion islands, and in northern giant petrels at Marion. There were no clear indications that timing of moult or migratory behavior affected mercury contamination patterns among species. Causes of inter-site or temporal differences in mercury contamination could not be verified due to a lack of long-term data related to species' diet and trophic levels, which should be collected in future together with data on mercury contamination. © 2016 Elsevier Ltd. Source


Ferrer J.,Av. Diagonal | Magret M.D.,Av. Diagonal | Pena M.,Av. Diagonal
International Journal of Bifurcation and Chaos | Year: 2010

Piecewise linear systems constitute a class of nonlinear systems which have recently attracted the interest of researchers because of their interesting properties and the wide range of applications from which they arise. Different authors have used reduced forms when studying these systems, mostly in the case where they are observable. In this work, we focus on bimodal continuous dynamical systems (those consisting of two linear systems on each side of a given hyperplane, having continuous dynamics along that hyperplane) depending on two or three state variables, which are the most common piecewise linear systems found in practice. Reduced forms are obtained for general systems, not necessarily observable. As an application, we calculate the dimension of the equivalence classes. © 2010 World Scientific Publishing Company. Source


Damasio J.,Jordi Girona | Damasio J.,University of Aveiro | Fernandez-Sanjuan M.,Jordi Girona | Sanchez-Avila J.,Jordi Girona | And 5 more authors.
Water Research | Year: 2011

Biological indexes, based on benthic macroinvertebrate taxa, are currently used worldwide to measure river ecological quality. These indexes assign a global ecological status of the biotic community, but not necessarily may detect specific effects of water pollutants. Conversely a large set of biochemical markers measured in macroinvertebrate benthic species can detect sublethal effects and inform us about additional environmental factors that are impairing benthic communities. This is especially interesting in moderately polluted sites, where other stressors are already affecting communities but not too strongly to be detected by biotic indexes. Up to ten different markers belonging to distinct metabolic paths and 42 contaminants measured in sample collections of the caddis fly Hydropsyche exocellata were assessed across a polluted gradient in the industrialized Mediterranean River basins of Besós and Llobregat (NE, Spain). Twenty four sample collections were selected to include macroinvertebrate communities representing the five impairment degrees defined by the Spanish Environmental authorities using the biotic metrics. Results evidenced a clear deterioration of the ecological water quality parameters and benthic communities towards downstream reaches. Biochemical responses varied significantly across the studied samples and were able to differentiate samples within communities having a good and deteriorated ecological stage. Principal Component Analyses indicated that salinity was one of the major stresses affecting macroinvertebrate assemblages, whereas antioxidant and metabolizing enzymes responded differently and were closely related to high and presumably toxic levels of accumulated organic pollutants. Therefore these results indicate that the use of multiple -markers sensitive to water pollution may provide complementary information to diagnose environmental factors that are impairing macroinvertebrate communities. © 2011 Elsevier Ltd. Source

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