Layerwise mixed least-squares finite element models for free vibration analysis of multilayered piezoelectric composite plates

This work provides an assessment of a finite element model based on layerwise mixed formulation using least squares applied to plate sandwich structures with skins made of piezoelectric layers and the core with composite angle play laminate layers. The extension to free vibration analysis is developed. The model assumes a layerwise variable description of displacements, transverse stresses and in-plane strains, taken as independent variables. The layerwise mixed formulation enables the fulfilment of the so-called C0z, yielding, for free vibration analysis a symmetric quadratic eigenvalue problem. The present model has nine degrees of freedom(dof ) per node in the core and in the upper and lower piezoelectric skins thirteen (nine to mechanical and four electrical) per node. The numerical examples show that the model predictive capabilities are in excellent agreement with three-dimensional exact solutions and also with available alternative models, from very thick to very thin sandwich piezoelectric plates.info:eu-repo/semantics/publishedVersio

Niche differences may reduce susceptibility to competition between native and non‐native birds in oceanic islands

Aim Few bird extinctions on oceanic island have been attributed to competition with non-native species, even though it might be an overlooked driver of biodiversity loss. We evaluate the potential competition between native and non-native island bird species, identifying species and island characteristics that enhance it and may promote future extinctions. Location Seventy-three (>100 km2) oceanic islands worldwide. Methods We compiled a species list for each island and used single-trait meta-analyses to assess differences between native and non-native species. Then, we used single-trait beta regression models to identify species traits linked to potential competition. Finally, we used a trait-based approach to calculate the potential competition between native and non-native species on each island and identify island characteristics linked to potential competition. Results Native bird species tended to be smaller forest dwellers, that were either carnivore, frugivore or insectivore, and that foraged in flight, in the canopy or at mid-height. In contrast, non-native birds tended to be open habitat granivores, that were either ground or unspecialized foragers. Potential competition tended to be higher for native species with typical non-native traits and forest-dwelling unspecialized non-native species. Potential competition between native and non-native birds was consistently higher in islands that were larger, had more non-native birds or were drier. Main conclusions Niche differentiation of native and non-native species may explain the scarcity of reported competition-driven extinctions since non-natives clearly tend to favour and are better adapted to anthropogenic environments. However, the few non-native birds that occur in native ecosystems may be problematic. The loss of native ecosystems coupled with the introduction of species that might outcompete native species may enhance the relevance of competition in future island extinctions.info:eu-repo/semantics/publishedVersio

Multimodal emotion evaluation: a physiological model for cost-effective emotion classification

Emotional responses are associated with distinct body alterations and are crucial to foster adaptive responses, well-being, and survival. Emotion identification may improve peoples' emotion regulation strategies and interaction with multiple life contexts. Several studies have investigated emotion classification systems, but most of them are based on the analysis of only one, a few, or isolated physiological signals. Understanding how informative the individual signals are and how their combination works would allow to develop more cost-effective, informative, and objective systems for emotion detection, processing, and interpretation. In the present work, electrocardiogram, electromyogram, and electrodermal activity were processed in order to find a physiological model of emotions. Both a unimodal and a multimodal approach were used to analyze what signal, or combination of signals, may better describe an emotional response, using a sample of 55 healthy subjects. The method was divided in: (1) signal preprocessing; (2) feature extraction; (3) classification using random forest and neural networks. Results suggest that the electrocardiogram (ECG) signal is the most effective for emotion classification. Yet, the combination of all signals provides the best emotion identification performance, with all signals providing crucial information for the system. This physiological model of emotions has important research and clinical implications, by providing valuable information about the value and weight of physiological signals for emotional classification, which can critically drive effective evaluation, monitoring and intervention, regarding emotional processing and regulation, considering multiple contexts.publishe

Metallurgical production evidences in the chalcolithic settlement of Moita da Ladra (Vila Franca de Xira, Portugal)

Poster apresentado na conferência realizada em Madrid de 1-3 de junho de 2015The archaeological site of Moita da Ladra is na emblematic settlement located at Vila Franca de Xira (Portugal), occupied predominantly during the second half of the 3rd millennia BC (Chalcolithic period). The presente study focuses on the chemical and microstructural characterization of selected artefacts and metallic nodules (metallurgical remains) found there. Its goal is to contribute to a better comprehension of the primitive copper-based metallurgy on the Portuguese estremadura, where other importante chalcolithic sites are located

Bird extinctions and introductions are causing taxonomic and functional homogenization in oceanic islands

Humans are quickly reshaping species assemblages through the loss and gain of species at multiple scales. Extinctions and introductions are non-random events known to be contributing to taxonomic homogenization. However, it is not yet clear if they also promote functional homogenization. Here, we assess whether extinctions and introductions are leading to taxonomic and functional homogenization of 64 oceanic island bird assemblages, belonging to 11 archipelagos. Based on island lists of extinct and extant, native and introduced species and on species traits, we use probabilistic hypervolumes in trait space to calculate functional beta-diversity before and after extinctions and introductions. Bird extinctions and introductions promoted taxonomic and functional homogenization on most oceanic islands. These results follow our expectations, considering previous studies on taxonomic homogenization, the predictable link between taxonomic and functional diversity, and the trait similarity of many introduced species, often adapted to anthropogenic habitats, linked to the non-randomness of bird introductions on islands. Taxonomic homogenization was more common across than within archipelagos, also corroborating previous studies describing stronger homogenization on islands that are further apart and thus had distinctive native assemblages. Surprisingly, the widespread loss of species with similar traits, namely large flightless birds, often led to functional differentiation across archipelagos. However, this differentiation effect tended to be offset by the homogenizing effect of introductions. Functional homogenization increases the vulnerability to global changes, by reducing the variability of responses to disturbance and thus the resilience of ecosystem services, posing a threat to human societies on islands. Our results highlight subtle variations in taxonomic and functional beta-diversity of bird assemblages in oceanic islands, providing important insights to allow a better assessment of how anthropogenic changes might alter ecosystem functioning, which is vital to develop effective long-term conservation strategies. Read the free Plain Language Summary for this article on the Journal blog.Peer reviewe

Estudo das evidências de produção metalúrgica no Outeiro Redondo (Sesimbra)

O Outeiro Redondo (Sesimbra) é um sítio arqueológico importante da Estremadura Portuguesa, predominantemente ocupado durante o Calcolítico Pleno/Final (segunda metade do III Milénio a.C.). Este estudo foca‑se na caracterização elementar e microestrutural de 12 artefactos em liga de cobre e de um fragmento de cadinho provenientes deste sítio, contribuindo assim para o conhecimento da metalurgia primitiva naquela região. A metodologia aplicada consistiu em espectrometria de fluorescência de raios ‑X dispersiva de energias, microscopia óptica, microscopia electrónica de varrimento com microanálise de raios ‑X e microdureza Vickers. O arsénio está presente em todos os fragmentos metálicos, quer como impureza (2 wt%), os quais apresentam constituintes microestruturais característicos de diversos processos termomecânicos. O cadinho mostra evidências de uso em operações metalúrgicas de redução de minérios.The pre‑historic settlement of Outeiro Redondo located near Sesimbra is an important archaeological site of the Portuguese Estremadura region, predominantly occupied during the Full/Late Chalcolithic period (second half of the 3rd millennium B.C.). The present study focuses on the elemental and microstructural characterization of a group of 12 copper ‑based artefacts and a crucible fragment recovered from this settlement, contributing to the understanding of the Chalcolithic metallurgy in this geographic area. The applied methodology consisted of energy dispersive X ‑ray fluorescence spectrometry, optical microscopy, scanning electron microscopy with energy dispersive spectrometry and Vickers microhardness. Arsenic is present in all the metallic fragments, – whether as impurity (2 wt%) – which exhibit microstructural features characteristic of several thermomechanical processes. The crucible shows evidence of use in metallurgical operations, namely smelting.Patrocinador oficial - Fundação Millennium BCP. Apoio institucional - Biblioteca Nacional de Portugal e Parques de Sintra- Monte da Lua. O Projecto Metalurgia Primitiva no Território Português – EarlyMetal (PTDC/HIS ‑ARQ/110442/2008) financiado pela Fundação para a Ciência e Tecnologia (FCT)

A tale of two species: the importance of native ecosystems for long-term conservation on Príncipe Island, Gulf of Guinea

Since it was first described in 1901, the Príncipe thrush Turdus xanthorhynchus has been rare and restricted to the native forest in the south of Príncipe Island. The Obô giant land snail Archachatina bicarinata, however, was widespread across the island and at least locally abundant until the 1990s. Since then its population has collapsed, and now, like the thrush, it is also restricted to the native forest in the south of the island. Using species distribution modelling, we show that both species are currently strongly associated with rugged and remote areas of native forest at high altitudes. We argue that their current distribution might be negatively affected by anthropogenic pressures, as both are harvested, and also because invasive alien species are expected to have deleterious effects on these species, although further studies are needed to clarify interactions between these native and introduced species. The diachronic stories of these species highlight an overlooked value of native ecosystems: their role in the conservation of widespread species that might be unable to use anthropogenic landscapes in the future. They also reinforce the need for protected areas that strive to exclude most human activities in the context of particularly sensitive biodiversity, as is often the case on oceanic islands.info:eu-repo/semantics/publishedVersio

Non-CG DNA methylation is a biomarker for assessing endodermal differentiation capacity in pluripotent stem cells.

Non-CG methylation is an unexplored epigenetic hallmark of pluripotent stem cells. Here we report that a reduction in non-CG methylation is associated with impaired differentiation capacity into endodermal lineages. Genome-wide analysis of 2,670 non-CG sites in a discovery cohort of 25 phenotyped human induced pluripotent stem cell (hiPSC) lines revealed unidirectional loss (Δβ=13%, P<7.4 × 10(-4)) of non-CG methylation that correctly identifies endodermal differentiation capacity in 23 out of 25 (92%) hiPSC lines. Translation into a simplified assay of only nine non-CG sites maintains predictive power in the discovery cohort (Δβ=23%, P<9.1 × 10(-6)) and correctly identifies endodermal differentiation capacity in nine out of ten pluripotent stem cell lines in an independent replication cohort consisting of hiPSCs reprogrammed from different cell types and different delivery systems, as well as human embryonic stem cell (hESC) lines. This finding infers non-CG methylation at these sites as a biomarker when assessing endodermal differentiation capacity as a readout.We thank Kerra Pearce (UCL Genomics) for array processing, and Tim Fell and Jonathan Best (CellCentric), Jason Wray (UCL) and Rosemary Drake (TAP Biosystems) for discussions. We also thank Minal Patel, Chris Kirton, Anja Kolb-Kokocinski, Willem H. Ouwehand, Richard Durbin and Fiona M. Watt on behalf of the Human Induced Pluripotent Stem Cell Initiative (HipSci) funded by grant WT098503 from the Wellcome Trust and the Medical Research Council, for sharing data and materials. This work was supported in part by a TSB/EPSRC grant (TS/H000933/1). The Vallier lab is supported by the Cambridge Hospitals National Institute for Health Research Biomedical Research Center and an ERC Starting Grant (Relieve IMDS). F.A.C.S. is funded by a PhD studentship from Fundação para a Ciência e a Tecnologia (SFRH/BD/69033/2010). The Ferguson-Smith lab is supported by grants from the MRC and Wellcome Trust, and EU-FP7 projects EPIGENESYS (257082) and BLUEPRINT (282510). The Beck lab is supported by the Wellcome Trust (084071), a Royal Society Wolfson Research Merit Award (WM100023), and EU-FP7 projects EPIGENESYS (257082) and BLUEPRINT (282510).This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/ncomms1045

Effects of conductive and non-conductive materials on the activity of a hydrogenotrophic methanogen

Several conductive materials (CM), such as carbon nanotubes (CNT), activated carbon (AC), and magnetite, have been reported to mediate interspecies electron transfer in methanogenic environments. However, CNT also accelerated methane production (MP) of pure cultures of methanogens. We hypothesize that other CM and also non-CM may affect the methanogenic activity of pure cultures. For that purpose, we incubated the hydrogenotrophic methanogen, Methanobacteriun formicicum strain DSM 1535T, with AC, zeolite (Zeo), sand and glass beads (at 0.5 g/L), and followed MP. All materials reduced lag phases preceding the MP, and the time for complete conversion of H2/CO2 to methane. The best results were obtained with Zeo, since total hydrogen conversion occurred in less than 5 days (instead of 8 days as in the control incubated without materials). Approximately 5 days with sand, and 6 days with glass beads and AC, were necessary to achieve the complete conversion. The lag phases with AC were quite short (1 day) when compared with the control assay without materials (5 days). The initial MP (determined during the first 3 days of incubation) was improved 16 times with Zeo and 11 times with AC, when compared with the cultures incubated without materials. The results show that there is not a direct relationship between conductivity and the improvement of methanogenic activity. Other physicochemical properties of the materials might be related with the beneficial effects towards methanogens.info:eu-repo/semantics/publishedVersio

Zeolite stimulates the activity of microbial enrichments converting butyrate to methane

Conductive materials have been tested as a strategy to improve methane production (MP) in anaerobic digestion (AD) processes1,2. The effect of zeolite (0.5 g/L) towards microbial enrichments converting butyrate (10 mmol/L) to methane was investigated and compared with a microbial enrichment in the absence of the material. The enrichments were initiated with granular anaerobic sludge from a brewery WWTP as inoculum. Incubations were carried out under strict anaerobic conditions (at 37 °C) and periodically transferred to fresh medium. The results showed that, after an initial adaptation period (3 transfers), the presence of zeolite significantly accelerated the total conversion of butyrate to methane, since it took approximately 30d with zeolite and around 45d without zeolite. However, both enrichment cultures after extended adaptation (more than 8 transfers) behaved similarly, degrading butyrate in approximately 15d. Nevertheless, zeolite addition to active butyrate enrichment cultures without previous contact with zeolite, slightly accelerated MP, while the highly adapted zeolite-enrichment decreased activity when incubated without zeolite. Thus, the presence of zeolite showed to stimulate the microbial activity enhancing MP from butyrate degradation. This material possess natural ion-exchange properties, absorptive capacity and could function as a support for biomass which makes its application very attractive to AD processes.info:eu-repo/semantics/publishedVersio