This dissertation is concerned with extensions and wedge products of positive currents. Our study can be considered as a generalization for classical works done earlier in this field. Paper I deals with the extension of positive currents across different types of sets. For closed complete pluripolar obstacles, we show the existence of such extensions. To do so, further Hausdorff dimension conditions are required. Moreover, we study the case when these obstacles are zero sets of strictly k-convex functions. In Paper II, we discuss the wedge product of positive pluriharmonic (resp. plurisubharmonic) current of bidimension (p,p) with the Monge-Ampère operator of plurisubharmonic function. In the first part of the paper, we define this product when the locus points of the plurisubharmonic function are located in a (2p-2)-dimensional closed set (resp. (2p-4)-dimensional sets), in the sense of Hartogs. The second part treats the case when these locus points are contained in a compact complete pluripolar sets and p≥2 (resp. p≥3). Paper III studies the extendability of negative S-plurisubharmonic current of bidimension (p,p) across a (2p-2)-dimensional closed set. Using only the positivity of S, we show that such extensions exist in the case when these obstacles are complete pluripolar, as well as zero sets of C2-plurisubharmoinc functions. / At the time of doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Accepted. Paper 2: Manuscript. Paper 3: Manuscript.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Baseados nos trabalhos De Gerhardt e Urbas [12], [36], provamos um resultado de convergÃncia global e determinamos precisamente o comportamento assintÃtico de soluÃÃes de um fluxo geomÃtrico que descreve a evoluÃÃo de hipersuperfÃcies estreladas e k-convexas por funÃÃes das curvaturas principais. Como aplicaÃÃo, e seguindo o argumento de Guan e Li [16], utilizamos um caso particular deste resultado de convergÃncia para generalizar a clÃssica desigualdade de Alexandrov-Fenchel para domÃnios estrelados e k-convexos. / Based on the work of Gerhardt and Urbasa [12], [36], we prove a global convergence result and precisely determine the asymptotic behavior of solutions of a geometric flow describing the evolution of starshaped, k-convex hypersurfaces according to certain functions of the principal curvatures. As an application, and following the argument of Guan and Li [16], we use a special case of this convergence result to generalize the classical Alexandrov-Fenchel inequality for domains starry and k-convex.