Orbifold boundary states from Cardy's condition

Boundary states for D-branes at orbifold fixed points are constructed in close analogy with Cardy's derivation of consistent boundary states in RCFT. Comments are made on the interpretation of the various coefficients in the explicit expressions, and the relation between fractional branes and wrapped branes is investigated for $\mathbb{C}^2/\Gamma$ orbifolds. The boundary states are generalised to theories with discrete torsion and a new check is performed on the relation between discrete torsion phases and projective representations.Comment: LaTeX2e, 50 pages, 5 figures. V3: final version to appear on JHEP (part of a section moved to an appendix, titles of some references added, one sentence in the introduction expanded

Un projet de développement innovant au Cap-Vert : le PRODAP

Les situations topographiques et le régime des pluies rencontrés au Cap-Vert en ont fait depuis quinze ans un laboratoire de la lutte antiérosive. Les techniques employées n'ont pas toujours atteint leur objectif en zone pluviale cultivée. En effet, elles sont le résultat d'une intervention de l'Etat plus que des paysans eux-mêmes. Le PRODAP propose depuis 1991 une autre approche de la lutte antiérosive. La gestion conservatoire de l'eau, de la biomasse et de la fertilité fait appel à la participation des agriculteurs en associant l'objectif d'amélioration de la production à celui de la protection du milieu. Après une première phase de diagnostic des différents milieux pédo-climatiques et des systèmes de production, le projet fait des propositions concrètes : capter les eaux de surface; améliorer l'infiltration de l'eau au champ par une meilleure couverture du sol afin d'augmenter les rendements et de diminuer l'érosion; rétablir l'équilibre minéral et organique du so

Action research and democracy

This contribution explores the relationship between research and learning democracy. Action research is seen as being compatible with the orientation of educational and social work research towards social justice and democracy. Nevertheless, the history of action research is characterized by a tension between democracy and social engineering. In the social-engineering approach, action research is conceptualized as a process of innovation aimed at a specific Bildungsideal. In a democratic approach action research is seen as research based on cooperation between research and practice. However, the notion of democratic action research as opposed to social engineering action research needs to be theorized. So called democratic action research involving the implementation by the researcher of democracy as a model and as a preset goal, reduces cooperation and participation into instruments to reach this goal, and becomes a type of social engineering in itself. We argue that the relationship between action research and democracy is in the acknowledgment of the political dimension of participation: ‘a democratic relationship in which both sides exercise power and shared control over decision-making as well as interpretation’. This implies an open research design and methodology able to understand democracy as a learning process and an ongoing experiment