1,414 research outputs found

    Eficiência reprodutiva de porcas bísaras em regime ar livre, com maneio simplificado.

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    Eficiência reprodutiva de porcas bísaras em regime ar livre, com maneio simplificado.info:eu-repo/semantics/publishedVersio

    Extensive beef cattle production in Portugal

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    Portugal, located in the Mediterranean region, one of the "Hot Spot" of the planet, has a huge variability in terms of topography, soils, climate, agriculture, traditions, resulting in a high diversity of animal genetic resources, represented by 15 native cattle breeds, most of them threatened. A significant percentage of extensive beef cattle production in Portugal is based on the use of animals, differing from north to south region, with good maternal aptitude, hardiness, a low growth performance and exceptional adaptation to the environment where they live, and especially to the local feed, naturally produced. In the north of the country and the Azores, dairy breeds predominate, while in the south beef breeds are most prevalent. Portugal is not self-sufficient in beef production, however it is possible to appreciate an market for beef produced by indigenous breeds from extensive and organic production systems. Beef from indigenous breeds is considered to be a high quality product, mainly because of the superior taste and structure of the meat resulting from the production system: slow growth rate and type of vegetation consumed. This product differentiation has allowed the enlargement of small niche markets and has led to an increase in the value of meat with a Protected Designation of Origin (PDO) or with organic beef. Since portuguese agriculture cannot compete on quantity or production cost with other competitors, differentiation and quality seem to be the alternatives that may stimulate rural activities in Less Favoured Areas (LFAs) and create a regional added value able to contribute to sustainable development. Extensive animal production systems can be an important component of environmental and landscape protection, as well as contribute to the decrease of the human, physical desertification of our rural areas and animal genetic resources

    Interaction of microplastics with metal(oid)s in aquatic environments: What is done so far?

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    Microplastics (MPs) are being recognized as an emergent route of contaminants to aquatic environments, which initially attracted the research interest on their interactions with organic pollutants. Lately, a turning point of attention is evident, with more published studies reporting the presence of metal(oid)s in plastics. This review assembles the mechanisms occurring on microplastics surfaces that enhance sorption of hazardous elements (i.e., metals and metalloids) over environmental exposure. Reported findings of experimental studies are of major importance to understand the factors controlling the sorption/desorption of metal(oid)s to/from microplastics as much as determination of metal(oid)s in environmental plastics. Existence or formation of oxygen-containing functional groups and complexes from surface coatings strongly allow bond of metal(oid)s on reactive surfaces while sorption dynamics are strongly controlled by water chemistry parameters. Moreover, the present work evidences the potential impacts caused by metal(oid)s-MPs interactions to aquatic organisms, prioritizing the need of environmental realistic parameters to test. Bioaccumulation of metal(oid)s desorbed from ingested MPs prove the significant influence of these plastic particles in the bioavailability of pollutants to aquatic biota. In this way, this is a comprehensive manuscript committed to the estimation of the potential ecological risk of MPs to aquatic environments due to their association with metal(oid)s.Versión del edito

    Operation of a perfusive catalytic membrane with nonlinear kinetics

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    Operation of a perfusive catalytic curved membrane is systematized into different transport-reaction regimes. The internal viscous permeation improves the catalyst performance, measured here by the effectiveness factor and by its enhancement relative to purely diffusive conditions. A theoretical analysis is presented for nonlinear kinetic expressions, which are suitable to describe the consumption of a reactant in many (bio)catalytic systems. The kinetic and transport parameters required to attain maximum enhancement are related by simple design rules, which depend on the form of the reaction rate law (namely on the order of reaction and dimensionless inhibition constant). For zero-order reactions, these optimum conditions correspond to attaining negligible concentration at a position inside the membrane, while may be interpreted in general as separating situations of severe mass transfer resistance from cases of high effectiveness. It is important to incorporate the correct form of the kinetic expression in the analysis, so that the predictions can be used in a quantitative manner. The results for the different regimes are compiled in enhancement plots and in Peclet–Thiele diagrams. Moreover, the study also yielded new results for the nonlinear reaction–diffusion problem in a curved membrane with its two surfaces exposed to different concentrations, a case of relevance in membrane reactors

    Medical ontology for treatment of clinical data from children and youth

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    The use of information technologies in the field of biomedical data management has grown considerably and is today one of the main fields of use of these technologies. There are several advantages arising either to an individual’s health or to public health, particularly because access to clinical data become available anywhere access via the Internet or individual health card. This card will contain personal data accessible from a terminal card reader, identical to the citizen card. This work focuses on the development of an ontology of universal data structure so that the information is accessible and organized in the same way, regardless of the system that use them. In this context there is the need to incorporate security mechanisms, the respect of ethical principles underlying the management and maintenance of clinical data, ensuring maximum confidentiality. To develop the proposed ontology, for the treatment of clinical data of children and youth is used as reference bulletin health in Portugal. Using this structure, it follows the clear and unambiguous identification of the fields required for registration of clinical information, standardized in a relational model. To ensure the confidentiality of data, identification of the individual is only the number of national health system and are not recorded on the card personal data such as name, address or contact forms

    Effects of irrigation on the vigour, yield and berry composition of the red variety Touriga Nacional at the Dão winegrowing region, Portugal

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    Proceedings - 17 th International Symposium GIESCO, Asti, Italy, 2011In a field trial installed at the Centro de Estudos Vitivinícolas do Dão, Nelas, Portugal, the effect of three irrigation treatments on the agronomic behaviour of cv Touriga Nacional (Vitis vinifera L.) were studied during three growing seasons (2006-2008). Three irrigation treatments (DI30 - irrigation with 30% of ETc; DI50 - irrigation with 50% ETc, FI - full irrigation – 100% Etc) were compared to a control non-irrigated treatment (NI). Compared to NI, the deficit irrigation treatments (DI30 & DI50) showed no significant differences on the yield and its components. The full irrigation treatment induced a significantly higher yield due to a higher bunch weight, as compared with the others treatments. Compared to the control, the deficit irrigation treatments presented similar berry composition during all the three seasons. The FI treatment presented, in all seasons, a significantly higher total acidity and a significantly lower Brix and total anthocyanins concentration as compared to the other treatments. The pruning weight and shoot weight increased with the amount of irrigation water applied, but significant differences were found only between the FI and the NI treatments, the last presenting the lowest values. Despite the fact that in the non-irrigated vineyards of the Dão winegrowing region it is very common to observe vine water stress symptoms, mainly during the ripening period, during the three studied seasons (2006-2008), the deficit irrigation treatments showed no advantages relatively to the control non-irrigated. Despite the higher yield produced in the full irrigation, this treatment had the disadvantages of the excessive vine vigour and lower must quality produced

    Magnetic phenomena in 5d transition metal nanowires

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    We have carried out fully relativistic full-potential, spin-polarized, all-electron density-functional calculations for straight, monatomic nanowires of the 5d transition and noble metals Os, Ir, Pt and Au. We find that, of these metal nanowires, Os and Pt have mean-field magnetic moments for values of the bond length at equilibrium. In the case of Au and Ir, the wires need to be slightly stretched in order to spin polarize. An analysis of the band structures of the wires indicate that the superparamagnetic state that our calculations suggest will affect the conductance through the wires -- though not by a large amount -- at least in the absence of magnetic domain walls. It should thus lead to a characteristic temperature- and field dependent conductance, and may also cause a significant spin polarization of the transmitted current.Comment: 7 pages, 5 figure

    Effect of vineyard floor management practices on water use: A case study at a terroir of the "Dão" winegrowing region in Portugal

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    Aiming to evaluate the effect of vineyard floor management practices on water use and vine performance, a field experiment was carried out at the Dão Wine Research Station, located at Nelas, Center Portugal. The experiment was set up in 2010 in a mature vineyard planted with the red grape variety ‘Touriga Nacional’, using a 2x2 factorial design with the following treatments: inter-row soil management (permanent resident vegetation vs. soil tillage) and undervine floor management (mulch vs. herbicide). In this paper it will be presented data from 2013 growing season (four seasons after experiment setup). The volumetric soil moisture, assessed with a capacitance probe to a 1.5 m depth, showed a decreasing pattern throughout the growing season in all treatments with the resident vegetation presenting lower values as compared to the tillage treatment, while no significant differences were observed between the two undervine floor management practices. From budburst to flowering the resident vegetation treatment showed a higher soil water depletion (up to 1.5 m depth) than the tillage treatment but the relative situation was reversed during the flowering-veraison period, while no significant differences were observed during the ripening period. Vine stem water potential values showed a decreasing pattern along the season attaining very low values during September but with no significant differences between treatments. In general the soil management practices did not significantly affect vine vigor, yield and berry composition however, since these results are only from one season, further data analysis in ongoing in order to allow stronger conclusions.info:eu-repo/semantics/publishedVersio

    Daily evolution of the components of the balance of radiation of vines in a vineyard in the Dão region

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    Proceedings - 17 th International Symposium GIESCO, Asti, Italy, 2011In order to validate a model of vine transpiration based on radiative surface temperature a field trial was conducted in a vineyard in the Dão region, centre of Portugal, with the cultivar “Touriga Nacional”. The model is based on the partition of net radiation between the components of the canopy (vines, soil, and grass cover), considering that the vines and the undercover (soil plus grass cover) act separately and in parallel. Thus, the latent heat flux from the vines to the atmosphere (lTc) is determined from vine net radiation (Rnc) and sensible heat flux (Hc). The partition of net radiation (Rn) between the undercover (Rns) and the vines (Rnc) is made considering the exponential form for radiation extinction, with the coefficient of extinction being corrected with a factor dependent on the zenital solar angle (j) while leaf area index (LAI) is corrected with a clumping factor, Ω(φ). Sensible heat flux from the vines (Hc) is calculated from radiative temperature (Tc) considering that the fluxes from the different origins are independent and that there are two resistances in series between the canopy and the atmosphere: the leaf boundary layer resistance (raHc) and the aerodynamic resistance of the crop (raH). Besides the estimation of the daily values of transpiration, the model allows to study the evolution of the different components of the radiation balance throughout the day. The daily evolution of the evaporation fraction from the vines (FEc) can be approximated by a concave curve. Values of FEc > 1 show that, under certain circumstances and periods of the day, energy used for transpiration (lTc) is greater than crop net radiation, which indicates that there are exchanges of energy between the several components of the surface, namely when evaporative demand from the atmosphere is high and there are no soil water restrictions. The model also shows that, regardless of the soil water status, transpiration is a big part of Rn when these values are low (in the beginning of the morning and late afternoon)
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