Browsing by Issue Date, starting with "2013-08"
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- Social careers of ex-drug abusers after the turning point of the therapeutic processPublication . Henriques, Susana; Candeias, PedroWith this communication is intended to present data from a research project in which we studied the social trajectories of ex-drug abusers after treatment in a therapeutic community.
- Auto-conceito global em estudantes do ensino superior: um estudo comparativo entre iniciantes e finalistasPublication . Barros, Rita; Moreira, J. AntónioEste estudo centra-se nos processos de mudança do autoconceito no período designado por pós-adolescência e traduz-se num estudo comparativo entre os níveis de autoconceito global de estudantes do ensino superior, iniciantes e finalistas. Recorrendo a uma metodologia de cariz quantitativo, a nossa amostra foi constituída por 552 sujeitos. Para a avaliação do nível de autoconceito global, valemo-nos da adaptação do Self Description Questionnaire III realizada por Faria e Fontaine (1992) a estudantes universitários portugueses. Concluímos que não existem diferenças significativas entre os dois grupos de estudantes. Esses resultados podem ser compreendidos com base nas experiências e ansiedades vivenciadas pelos estudantes do ensino superior, quer no processo de adaptação ao contexto acadêmico, no caso dos que estão a iniciar a formação, quer na antecipação de reais dificuldades de inserção no mercado de trabalho, no caso dos finalistas.
- Electrolytic conductivity of four imidazolium-based ionic liquidsPublication . Calado, Marta; Diogo, João C. F.; Mata, José L. Correia da; Caetano, Fernando J. P.; Visak, Zoran P.; Fareleira, João M. N. A.In this article, electrolytic (ionic) conductivity measurements of four ionic liquids (ILs), namely, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide ([C2mim][NTf2]), 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([C2mim][OTf]), 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C6mim][NTf2]), and 1-ethyl-3-methylimidazolium ethyl sulfate ([C2mim][EtSO4]) (ECOENG212 ), were performed in a temperature range of (288.15 to 333.15) K. [C6mim][NTf2] was chosen to be a reference ionic liquid for several properties, including the electrolytic conductivity by the IUPAC Project 2002-005-1-100. For that reason, the measurements performed with that ionic liquid primarily serve the purpose to validate the instrumentation and the experimental procedure used in this work. The measurements were carried out using a complex impedance method, applying a novel electronic device designed and constructed for this purpose. The complete setup includes a Schott Instruments LF 913 T, used as a four-electrode conductivity cell, and a lock-in amplifier. The cell was calibrated using standard reference KCl aqueous solutions. The measurements of the impedance of the conductivity cell were carried out along a range of frequencies from (0.2 to 30) kHz, and the results were extrapolated to infinite frequency, in order to determine the electrolytic conductivity of the liquid samples. The results obtained for the ionic liquid [C6mim][NTf2] were compared to reference data, and it was estimated that the overall uncertainty of the present results is better than 2%. All the data obtained were compared with available literature data, and were analyzed and discussed in respect to the effect of temperature, cation alkyl chain length, and anion.
- The universal covering map in o-minimal expansions of groupsPublication . Edmundo, Mário; Eleftheriou, P. E.; Prelli, L.In this paper we study locally definable manifolds and we prove: (i) the existence of universal locally definable covering maps; (ii) invariance results for locally definable covering maps, o-minimal fundamental groups and fundamental groupoids; (iii) monodromy equivalence for locally constant o-minimal sheaves; (iv) classification results for locally definable covering maps; (v) o-minimal Hurewicz and Seifert-van Kampen theorems.
- Discrete subgroups of locally definable groupsPublication . Berarducci, A.; Edmundo, Mário; Mamino, M.We work in the category of locally definable groups in an o-minimal expansion of a field. Eleftheriou and Peterzil conjectured that every definably generated abelian connected group G in this category is a cover of a definable group. We prove that this is the case under a natural convexity assumption inspired by the same authors, which in fact gives a necessary and sufficient condition. The proof is based on the study of the zero-dimensional compatible subgroups of G. Given a locally definable connected group G (not necessarily definably generated), we prove that the n-torsion subgroup of G is finite and that every zero-dimensional compatible subgroup of G has finite rank. Under a convexity hypothesis, we show that every zero-dimensional compatible subgroup of G is finitely generated