Utopías para el siglo XXI = Utopies per al segle XXI

Dossier realitzat pels estudiants de l'assignatura "Utopia i Vanguàrdia" (any acadèmic 2018-2019) del Grau d'Estudis en Arquitectura de la Universitat de Girona.Professora responsable: Marisa García VergaraMarisa García Vergara, docent del curs Adriana Vázquez Balló i Fèlix Breton Coll, assistents de docència Disseny i maquetació: Júlia Capdevila, Aina Brugués i Lídia PérezEste dossier recoge algunas experiencias arquitectónicas y urbanísticas que se han planteado en las últimas décadas, que se entroncan en la nutrida vertiente de las propuestas utópicas en nuestro campo de estudios en el último cuarto de siglo hasta la actualidadThis dossier gathers some architectural and urbanistic experiences that have been raised in the last decades, which are linked in the nourished slope of the utopian proposals in our field of studies in the last quarter of the century until toda

Coherent vector pi-pulse in optical amplifiers

We obtain an exact linearly polarized vector solitary solution for the amplification of an optical pulse with a time width short compared with both population and polarization decay time. This dissipative soliton results from the balance between the gain from inverted resonant two-level atoms and the linear loss of the host material. We suppose that the excited state of the active centers is degenerate on the projection of the angular momentum, with a symmetric state of inversion. Quite remarkably, we find that after the passing of the pulse, the atomic medium does not return to the ground state, and a finite Zeeman coherence is generated. Numerical simulations demonstrate the stability of vector π solitons with an arbitrary state of elliptical polarization in the presence of both linear birefringence and group-velocity dispersion of the host material