Scale dependent three-dimensional charged black holes in linear and non-linear electrodynamics

In the present work we study the scale dependence at the level of the effective action of charged black holes in Einstein-Maxwell as well as in Einstein-power-Maxwell theories in (2+1)-dimensional spacetimes without a cosmological constant. We allow for scale dependence of the gravitational and electromagnetic couplings, and we solve the corresponding generalized field equations imposing the "null energy condition". Certain properties, such as horizon structure and thermodynamics, are discussed in detail.Comment: v1: 13 pages, 10 figure

Four dimensional Einstein-power-Maxwell black hole solutions in scale-dependent gravity

In the present work, we extend and generalize our previous work regarding the scale dependence applied to black holes in the presence of non-linear electrodynamics (Rincón et al., 2017). The starting point for this study is the Einstein-power-Maxwell theory with a vanishing cosmological constant in (3+1) dimensions, assuming a scale dependence of both the gravitational and the electromagnetic coupling. We further examine the corresponding thermodynamic properties and how these quantities experience deviations from their classical counterparts. We solve the effective Einstein’s field equations using the “null energy condition” to obtain analytical solutions. The implications of quantum corrections are also briefly discussed. Finally, we analyze our solutions and compare them to related results in the literature.The author A. R. acknowledges DI-VRIEA for financial support through Proyecto Postdoctorado 2019 VRIEA-PUCV. P. B. is funded by the Beatriz Galindo contract BEAGAL 18/00207 (Spain). The author G. P. thanks the Fundação para a Ciência e Tecnologia (FCT), Portugal, for the financial support to the Center for Astrophysics and Gravitation-CENTRA, Instituto Superior Técnico, Universidade de Lisboa , through the Grant No. UID/FIS/00099/2013

Building ethnographic knowledge: reflections from field experience in school institutions

This paper discusses challenges, dilemmas and critical situations that arise when doing ethnography in public schools serving to low-income segments in Chile. We reflect on specific experiences during ethnographic fieldwork. First, the entrance or access to schools is addressed, which requires a negotiation process where the context, actors and ways of interacting conditions the future of the ethnographic research. Second, we reflect on positions attributed to the researcher by actors of the educational community once inside the school. These circumstances influence the viewpoint of the ethnographer and his or her relationship to school culture and its agents. Given the lack of similar work in Chile, this article is expected to contribute to the development of greater reflexivity in ethnographic work.El presente artículo aborda desafíos, dilemas y situaciones críticas que se presentan al realizar etnografía escolar en escuelas públicas que atienden a sectores populares en Chile. Para esto se reflexiona sobre experiencias concretas vividas en el trabajo de terreno. En primer lugar, se aborda la entrada o acceso a la escuela, momento que requiere de un proceso de negociación donde el contexto, los actores y las maneras de interactuar condicionan el futuro de la investigación etnográfica. Luego, sobre las posiciones atribuidas al investigador por parte de los actores de la comunidad educativa una vez que se encuentra dentro de la escuela, circunstancias que influyen sobre el punto de vista del etnógrafo y su relación con la cultura escolar y sus agentes. Dada la carencia de trabajos similares en Chile, se espera que este artículo aporte al desarrollo de una mayor reflexividad en el ámbito de la etnografía escolar