Asymptotically flat spacetimes in 3D bigravity

We report that a class of three-dimensional bimetric theories contain asymptotically flat solutions. These spacetimes can be cast in a set of asymptotic conditions at null infinity which are preserved under the infinite dimensional BMS group. Moreover, the algebra of the canonical generators exhibits a central extension. The possibility that these solutions describe regular black holes is also discussed.Comment: 6 page

Boundary dynamics of asymptotically flat 3D gravity coupled to higher spin fields

We construct a two-dimensional action principle invariant under a spin-three extension of BMS$_3$ group. Such a theory is obtained through a reduction of Chern-Simons action with a boundary. This procedure is carried out by imposing a set of boundary conditions obtained from asymptotically flat spacetimes in three dimensions. When implementing part of this set, we obtain an analog of chiral WZW model based on a contraction of $sl(3,\mathbb{R}) \times sl(3,\mathbb{R})$. The remaining part of the boundary conditions imposes constraints on the conserved currents of the model, which allows to further reduce the action principle. It is shown that a sector of this latter theory is related to a flat limit of Toda theory.Comment: 16 pages, no figure

Supertranslations and Superrotations at the Black Hole Horizon

We show that the asymptotic symmetries close to nonextremal black hole horizons are generated by an extension of supertranslations. This group is generated by a semidirect sum of Virasoro and Abelian currents. The charges associated with the asymptotic Killing symmetries satisfy the same algebra. When considering the special case of a stationary black hole, the zero mode charges correspond to the angular momentum and the entropy at the horizon.Comment: 6 pages, references added, published versio

Synthesis of fused tetrazolo iminosugars from azido monosaccharide derivatives

Synthesis of fused tetrazolo iminosugars from azido monosaccharide derivativesUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Revisiting the mechanism of the mono nuclear copper-catalyzed cycloaddition of azide and alkynes (CuAAC) by the topology of ....

Comunicación presentada y aceptada en el CHITEL2013, XXXIX International Conference THEORETICAL CHEMISTS OF LATIN EXPRESSION (XXXIX Congreso Internacional de Químicos de Expresión Latina).Se analiza el mecanismo de la reacción de cicloadición, catalizada por Cu(I), de azidas a alquinos (CuAAC), haciendo uso de métodos DFT y de herramientas de análisis de la densidad electrónica basadas en la topología de su laplaciana

The socle of a Leavitt path algebra

In this paper we characterize the minimal left ideals of a Leavitt path algebra as those ones which are isomorphic to principal left ideals generated by line point vertices, that is, by vertices whose trees do not contain neither bifurcations nor closed paths. Moreover, we show that the socle of a Leavitt path algebra is the two-sided ideal generated by these line point vertices. This characterization allows us to compute the socle of some algebras that arise as the Leavitt path algebra of some row-finite graphs. A complete description of the socle of a Leavitt path algebra is given: it is a locally matricial algebra.Comment: 13 pg

Intramolecular [3+2] Cycloaddition of Fused Azolo-Azepanes from Azido Monosaccharides Derivatives

Síntesis de bicíclicos compuestos empleando epoxiamidas como material de partida. Obtención de tetrazolo azepanos con posible actividad biológica.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Promoting collaboration in a competitive context: school improvement networks in Chile

ABSTRACT: Chile has developed the school improvement networks (SINs) strategy to support the work of school leaders. The purpose of this paper is to analyze the functioning and effect of the SINs strategy as perceived by principals and curriculum coordinators across the country. DESIGN/METHODOLOGY/APPROACH: An adapted version of the Educational Collaborative Network Questionnaire was applied to a sample of 1,723 participants from 1,375 schools distributed in 398 networks. Descriptive, factor and sub-group statistical analyses by school performance categories and by different roles within these schools and networks are presented. FINDINGS: Results indicate that school leaders perceive SINs as an opportunity to work effectively in shared projects that can later be implemented in their own schools. Participants indicate that they can share knowledge in their networks and use it to solve problems in their own schools, which is especially relevant for secondary school leaders who work in difficult circumstances. Results suggest that it is important to facilitate greater autonomy for school leaders in their networks, especially regarding decision making about network goals and activities that are more significant to their contexts. ORIGINALITY/VALUE: This is a national study of a recent school improvement strategy, which provides evidence, from the perspective of school leaders, of its strengths and improvement areas. This study shows that despite being in a competitive context, principals and curriculum coordinators value the opportunities to learn from and with others. These results can be of value for other contexts attempting to promote school networks as a means for school and system improvement