On Type II strings in exact superconformal non-constant RR backgrounds

An explicitly exact superconformal description is provided to some classes of Type II string theories in non constant RR backgrounds. This is done by applying the manifest (2,2) approach of Berkovits and Maldacena to Type II strings and by studying the condition of exact conformal invariance of certain supersymmetric backgrounds. We find a new set of exact type IIA strings with non constant RR 2-form and 4-form curvatures and for type IIB with non constant 3-form curvature.Comment: 15 pages; typos and a reference adde

Buoyancy and local friction effects on rockfill settlements: A discrete modelling

AbstractMeasured displacements in the upstream shell of rockfill dams show some settlements which can reach a few meters with water levels changes, especially during the first impounding, whereas downstream displacements are smaller. Complementary phenomena are responsible for rockfill collapse due to wetting. Here we numerically investigate the effects of buoyancy forces and the decrease in the coefficient of friction with water on a rockfill column maintained by vertical rigid walls and progressively filled with water. Numerical simulations of the settlements of the rockfill column, using the Contact Dynamics method, are presented. Buoyancy forces seem to have only a negligible influence on the granular pile. Decrease in the friction angle of the rock with water induces rearrangements of the medium, all the more as the decrease is significant. These dynamic rearrangements exhibit an irregular temporal evolution of the granular medium which can be characterized by a phenomenon of local “crisis”. Analysis of the settlements shows that these two combined effects are not the major cause of the settlements observed in rockfill dams and that they cannot in particular explain the settlements

Alter-Native Visions:Reflections on Ontological Multiplicity and Alterity in Southern Chile

En el presente artículo exploro la relevancia crucial de la “visión” como el eje central sobre el cual distintos mundos son enactuados en distintas prácticas de salud en el Sur de Chile. En este trabajo intento demostrar que el mundo indígenarural, a pesar de una larga historia de colonización, violento conflicto y contacto con las sociedades chilenas, presenta características que le son propias y a la vez inconmensurables con modelos de salud estatal basados en premisas multiculturales. Esta aseveración, sin embargo, no intenta diluir los distintos mundos múltiples que existen dentro del mundo indígena rural, los que presentan diferencias substanciales pero también comparten premisas ontológicas básicas sobre lo que es “el ver”, y por lo tanto, sobre lo que es el diferenciar la causa de las enfermedades. Así, a nivel más teórico,el siguiente trabajo busca reconceptualizar tensiones irresueltas entre los modos en los que diferencias ontológicas han sido propuestas en el “giro ontológico” en antropología y en la teoría del actor-red en los Estudios Sociales de la Ciencia y la Tecnología (CTS).In this article, I explore the centrality of “vision” as the axis around which different healing practices – related to different ontologies – turn. I intend to demonstrate that, despite a long history of colonization, violent conflicts and contact between Chilean societies and indigenous peoples in Southern Chile, Pewenche rural worldsare predicated upon ontological premises that are not commensurable with multicultural health state programmes. This statement, however, does not obscure the ontological multiplicity internal to the rural indigenous world. Despite this internal multiplicity, however, I show how these ontological differences are predicated upon similar ontological premises about what ‘vision’ and healingentail. At a more theoretical level, the following ethnographic account sheds light on unresolved tensions between the ways ontological difference has been conceptualized within the so-called ‘ontological turn’ in anthropology and within the field of Science and Technologies Studies (STS), particularly regarding Actor-Network Theory (ANT)