3 resultados para Big Five

em Instituto Politécnico do Porto, Portugal


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Purpose – This research aims to understand the role played by social entrepreneurs’ personality traits on the choice between the traditional donation model and social crowdfunding (CF) to finance social projects. Design/methodology/approach – Social CF is examined as an instrument to capture funds for social projects, and the particular case of the Portuguese Social Stock Exchange (PSSE) is presented. The approach is quantitative in nature and the data were collected through a questionnaire that was emailed to non-governmental organizations in Portugal and founders of the projects listed on PSSE. Logistic regression was employed to predict the probability that a social entrepreneur would use PSSE rather than traditional financing. The predictor variables were based on the big five personality traits. Findings – Our investigation reveals that the agreeableness and neuroticism factors were not even considered in the results of the factorial analysis, which indicates the minor importance of these personality traits in the funding decisions of the Portuguese social entrepreneurs. The same applies to the factors of openness to new experiences and extraversion, which, although considered in the logistic analysis, showed no statistical significance. Finally, the conscientiousness personality trait seems to be the only factor that might explain the use of the PSSE platform.Originality/value – Studies on the profile of the social entrepreneurs that use CF for financing social projects are relatively rare, specifically in the context of Social Stock Exchange platforms. Additionally, there is a need to carry out more empirical evidence about the effect of social entrepreneurs’ personality traits on the decision to finance social projects through social CF platforms vis-a-vis the traditional donation model.

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The introduction of new distributed energy resources, based on natural intermittent power sources, in power systems imposes the development of new adequate operation management and control methods. This paper proposes a short-term Energy Resource Management (ERM) methodology performed in two phases. The first one addresses the hour-ahead ERM scheduling and the second one deals with the five-minute ahead ERM scheduling. Both phases consider the day-ahead resource scheduling solution. The ERM scheduling is formulated as an optimization problem that aims to minimize the operation costs from the point of view of a virtual power player that manages the network and the existing resources. The optimization problem is solved by a deterministic mixed-integer non-linear programming approach and by a heuristic approach based on genetic algorithms. A case study considering a distribution network with 33 bus, 66 distributed generation, 32 loads with demand response contracts and 7 storage units has been implemented in a PSCADbased simulator developed in the field of the presented work, in order to validate the proposed short-term ERM methodology considering the dynamic power system behavior.

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GOAL: The manufacturing and distribution of strips of instant thin - layer chromatography with silica gel (ITLC - SG) (reference method) is currently discontinued so there is a need for an alternative method f or the determination of radiochemical purity (RCP) of 99m Tc - tetrofosmin. This study aims to compare five alternative methods proposed by the producer to determine the RCP of 99m Tc - tetrofosmin. METHODS: Nineteen vials of tetrofosmin were radiolabelled with 99m Tc and the percentages of the RCP were determined. Five different methods were compared with the standard RCP testing method (ITLC - SG, 2x20 cm): Whatman 3MM (1x10 cm) with acetone and dichloro - methane (method 1); Whatman 3MM (1x1 0 cm) with ethyl acetate (method 2); aluminum oxide - coated plastic thin - layer chromatography (TLC) plate (1x10 cm) and ethanol (method 3); Whatman 3MM (2x20 cm) with acetone and dichloro - methane (method 4); solid - phase extraction method C18 cartridge (meth od 5). RESULTS: The average values of RCP were 95,30% ± 1,28% (method 1), 93,95 ± 0,61% (method 2), 96,85% ± 0,93% (method 3), 92,94% ± 0,99% (method 4) and 96,25% ± 2,57% (method 5) (n=12 each), and 93,15% ± 1,13% for the standard method (n=19). There we re statistical significant differences in the values obtained for methods 1 (P=0,001), 3 (P=0,000) and 5 (P=0,004), and there were no statistical significant differences in the values obtained for methods 2 (P=0,113) and 4 (P=0,327). CONCLUSION: From the results obtained, methods 2 and 4 showed a higher correlation with the standard method. Unlike method 4, method 2 is less time - consuming than the reference method and can overcome the problems associated with the solvent toxicity. The remaining methods (1, 3 and 5) tended to overestimate RCP value compared to the standard method.