1,020 research outputs found

    Fundamentos teóricos e metodológicos para o ensino-aprendizagem de astronomia

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    O curso Fundamentos Metodológicos para o Ensino e Aprendizagem de Astronomia é um projeto que pretende promover e incentivar o ensino de Astronomia, no Oeste de Paraná e na tríplice fronteira, com a participação da universidade no processo de capacitação de professores da rede de escolas públicas do Estado. Com um curso de 72 horas, no qual se faz uso de diversas tecnologias e atividades pedagógicas, realizado nas instalações do Polo Astronômico Casimiro Montenegro Filho da fundação Parque tecnológico Itaipu, se fornecem novas ferramentas de ensino aos professores os quais posteriormente utilizarão os conhecimentos adquiridos para o ensino de forma adequada e fundamentada aos estudantes das escolas. Com isso, espera-se que esta ação possa contribuir positivamente para propagação de conhecimento a nível regional nesta área de conhecimento cientifico, incentivando as novas gerações a pensar e explorar tudo o que o universo oferece

    Functional MRI with active, fully implanted, deep brain stimulation systems: Safety and experimental confounds

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    We investigated safety issues and potential experimental confounds when performing functional magnetic resonance imaging (fMRI) investigations in human subjects with fully implanted, active, deep brain stimulation (DBS) systems. Measurements of temperature and induced voltage were performed in an in vitro arrangement simulating bilateral DBS during magnetic resonance imaging (MRI) using head transmit coils in both 1.5 and 3.0 T MRI systems. For MRI sequences typical of an fMRI study with coil-averaged specific absorption rates (SARs) less than 0.4 W/kg, no MRI-induced temperature change greater than the measurement sensitivity (0.1 °C) was detected at 1.5 T, and at 3 T temperature elevations were less than 0.5 °C, i.e. within safe limits. For the purposes of demonstration, MRI pulse sequences with SARs of 1.45 W/kg and 2.34 W/kg (at 1.5 T and 3 T, respectively) were prescribed and elicited temperature increases (> 1 °C) greater than those considered safe for human subjects. Temperature increases were independent of the presence or absence of active stimulator pulsing. At both field strengths during echo planar MRI, the perturbations of DBS equipment performance were sufficiently slight, and temperature increases sufficiently low to suggest that thermal or electromagnetically mediated experimental confounds to fMRI with DBS are unlikely. We conclude that fMRI studies performed in subjects with subcutaneously implanted DBS units can be both safe and free from DBS-specific experimental confounds. Furthermore, fMRI in subjects with fully implanted rather than externalised DBS stimulator units may offer a significant safety advantage. Further studies are required to determine the safety of MRI with DBS for other MRI systems, transmit coil configurations and DBS arrangements

    Towards honey authentication: Differentiation of Apis mellifera subspecies in European honeys based on mitochondrial DNA markers

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    Honey is the natural sweet substance produced by Apis mellifera honeybees in Europe. Depending on the country/region, the A. mellifera subspecies native to Europe belong to three different lineages: A (A. m. iberiensis), M (A. m. iberiensis and A. m. mellifera) and C (A. m. ligustica and A. m. carnica). In this work, two DNAbased approaches were developed with the aim of entomological authentication of European honeys. A cytb specific PCR assay was proposed to identify A-lineage honeybees, while a second method based on real-time PCR coupled to high resolution melting analysis targeting the COI gene was developed to differentiate C- and Mlineages honeybees. The proposed methodologies were validated successfully with honeys of known origin and applied to the entomological authentication of 20 commercial samples from different European countries. The results highlight the predominance of honeys from C-lineage honeybees in Europe, except in Iberian Peninsula countries (honey from A-lineage honeybees).The authors are grateful to Dora Henriques for assembling the mitogenomes and to Pilar de la Rua and António Pajuelo for supplying authentic honey samples. This work was supported by FCT (Fundação para a Ciência e Tecnologia) through project UID/QUI/50006/2013 – POCI/01/0145/FEDER/007265 with financial support from FCT/MEC through national funds and co-financed by FEDER, under the Partnership Agreement PT2020 and by the projects NORTE-01-0145- FEDER-000011 and BeeHappy – POCI-01-0145-FEDER-029871 (financed by FEDER through the COMPETE 2020 – Operational Programme for Competitiveness and Internationalisation (POCI) and FCT). S. Soares, L. Grazina and J. Costa are grateful to FCT grants (SFRH/BD/75091/2010, SFRH/BD/132462/2017 and SFRH/BPD/102404/2014, respectively) financed by POPH-QREN (subsidised by FSE and MCTES).info:eu-repo/semantics/publishedVersio

    Studying the ZnO formation in coated steel wire ropes for the automotive industry

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    30th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM2021) 15-18 June 2021, Athens, GreeceBowden cables are abundantly applied in the automotive assembly lines leading to drive various devices, such as opening trunk or the fuel tank cap, triggering the handbrake, opening the doors, etc. The cable used in automotive metallic harness is commonly constituted of braided wire galvanized steel, which has been studied to resist the weather aggressions typically imposed by the conditions under which usually work. However, to allow this operating in a steady state way, the braided wire must have the appropriate quality. This work study the reasons of the formation of relatively abundant quantities of zinc oxide (ZnO) in metallic cables used in the automotive industry, a few weeks after their manufacture. It was concluded that there were serious shortcomings of cable cleaning between the wire forming operations and galvanizing, with deposition of ZnO enhancing elements in the interface, which would prove to be crucial to nucleation and development of ZnO on the surface. Thus, the main contribution of this work is to identify and describe the elements able to generate ZnO in coated steel wires, avoiding this phenomenon in the industry.info:eu-repo/semantics/publishedVersio

    Root functioning, tree water use and hydraulic redistribution in Quercus suber trees: a modeling approach based on root sap flow

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    Mediterranean evergreen oaks have to survive a long summer drought. Roots may play a relevant role under these conditions. We studied their structure and function in a mature Quercus suber L. tree in central Portugal. The root system was mapped till the lowest water table level (4.5 m depth). Xylem anatomy was analyzed in a vertical profile belowground. Sap flow was continuously monitored for 1.5 yrs in the stem and roots of this intensively studied tree (heat field deformation method) and in the stem of four trees (Granier method), in relation to environmental variables and predawn leaf water potential. The sources of water uptake were assessed by stable isotope analyses in summer. Results showed a dimorphic root system with a network of superficial roots linked to sinker roots, and a taproot diverting into tangles of deep fine roots submerged for long periods, with parenchyma aerenchyma. Transpiration was not restricted in summer due to root access to groundwater. The isotopic d18O signature of twig xylem water was similar to that of groundwater in the dry season. Two functional types of superficial roots were identified: shallow connected and deep connected roots. A modeling approach was built considering that each superficial root was linked to a sinker, with part of the root deep connected (between the stem and the sinker) and part shallow connected (between the sinker and topsoil). This conceptual framework simulated tree stem sap flow from root sap flow with a high efficiency (R2 = 0.85) in four plot trees. On an annual basis, soil water and groundwater contributions were 69.5% and 30.5% of stem flow, respectively. Annual hydraulic lift and hydraulic descent were 0.9% and 37.0% of stem flow, respectively. The trees maximize the exploitation of the environmental resources by using the topsoil water during most of the year, and groundwater together with hydraulic lift (nutrient supply) in the dry summer. This study shows that a dimorphic root system, with roots reaching groundwater, is an efficient strategy of Q. suber trees to cope with seasonal drought. Knowledge of the functional behavior of Q. suber trees under shallow water table conditions may contribute to the definition of better adapted management practices and to anticipate their responses to climate chang

    Modulation Of The Catalytic Activity Of Porphyrins By Lipid- And Surfactant-containing Nanostructures

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    The structural factors modulating porphyrin activity encompass pyrrole and equatorial ligands, as well as the central metal and the number and structure of their axial ligands. Of equal importance is the microenvironment provided by apoproteins, solvents and membranes. Porphyrins are often used to construct supramolecular structures with different applications. The modulation of activity of the porphyrins has been frequently achieved by mimicking nature, i.e., by the provision of different microenvironments for these molecules. The association of porphyrins to surfactant- and lipid-containing nanostructures has changed the activity of these compounds to mimic different enzymes such as SOD, cytochrome P450, peroxidases and others. In determined conditions, the reactive forms of the porphyrins are high-valence states of oxo-metal-π cations and oxo-metal produced by the reaction with peroxides and peracids. 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    Zeta function method and repulsive Casimir forces for an unusual pair of plates at finite temperature

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    We apply the generalized zeta function method to compute the Casimir energy and pressure between an unusual pair of parallel plates at finite temperature, namely: a perfectly conducting plate and an infinitely permeable one. The high and low temperature limits of these quantities are discussed; relationships between high and low temperature limits are estabkished by means of a modified version of the temperature inversion symmetry.Comment: latex file 9 pages, 3 figure

    The role of natural regeneration to ecosystem services provision and habitat availability: a case study in the Brazilian Atlantic Forest

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    Natural regeneration provides multiple benefits to nature and human societies, and can play a major role in global and national restoration targets. However, these benefits are context specific and impacted by both biophysical and socioeconomic heterogeneity across landscapes. Here we investigate the benefits of natural regeneration for climate change mitigation, sediment retention and biodiversity conservation in a spatially explicit way at very high resolution for a region within the global biodiversity hotspot of the Atlantic Forest. We classified current land-use cover in the region and simulated a natural regeneration scenario in abandoned pasturelands, areas where potential conflicts with agricultural production would be minimized and where some early stage regeneration is already occurring. We then modelled changes in biophysical functions for climate change mitigation and sediment retention, and performed an economic valuation of both ecosystem services. We also modelled how land-use changes affect habitat availability for species. We found that natural regeneration can provide significant ecological and social benefits. Economic values of climate change mitigation and sediment retention alone could completely compensate for the opportunity costs of agricultural production over 20 years. Habitat availability is improved for three species with different dispersal abilities, although by different magnitudes. Improving the understanding of how costs and benefits of natural regeneration are distributed can be useful to design incentive structures that bring farmers’ decision making more in line with societal benefits. This alignment is crucial for natural regeneration to fulfil its potential as a large-scale solution for pressing local and global environmental challenges

    The Portuguese Third Version of the Copenhagen Psychosocial Questionnaire: Preliminary Validation Studies of the Middle Version among Municipal and Healthcare Workers

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    A third version of the Copenhagen Psychosocial Questionnaire (COPSOQ III) was developed internationally aiming to respond to new trends in working conditions, theoretical concepts, and international experience. This article aims to present the preliminary validation studies for the Portuguese middle version of COPSOQ III. This is an exploratory cross-sectional study viewing the cross-cultural adaption of COPSOQ III to Portugal, ensuring the contents and face validity and performing field-testing in order to reduce the number of items and to obtain insight into the data structure, through classic test theory and item response theory approaches. The qualitative study encompassed 29 participants and the quantitative one 659 participants from municipalities and healthcare settings. Content analysis suggested that minor re-wording could improve the face validity of items, while a reduced version, with 85 items, shows psychometric stability, achieving good internal consistency in all subscales. The COPSOQ III Portuguese middle version proved to be a valid preliminary version for future validation studies with various populations, able to be used in correlational studies with other dimensions
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