Type IIA/M-theory Moduli fixing in a Class of Orientifold Models

We present the study of type II A flux vacua and their M-theory duals for compactification on a class of Calabi-Yau orientifolds. The Kaehler potential is derived from toroidal compactifications and the superpotential contains a contribution from non-Abelian gauge degrees of freedoms. We obtain complete stabilisation of the moduli. We found one supersymmetric minimum and several non supersymmetric ones. Consistency of the analysis constrains the parameters of the models in a finite region containing a finite, although very large, number of flux vacua. From the M-theory side, we found some differences in the distributions of the physical quantities with respect to the M-theory ensemble studied by Acharya et al. In particular, it is easier to find small supersymmetry breaking scale.Comment: 37 pages, 4 figures, LaTeX. Extended one Section, added reference

Exact Gravitational Dual of a Plasma Ball

We present an exact solution for a black hole localized near an infrared wall in four-dimensional anti-deSitter space. By computing the holographic stress tensor we show that the CFT dual of the black hole is a 2+1-dimensional ball (i.e., a disk) of plasma at finite temperature, surrounded by vacuum. This confirms some earlier conjectures about plasma balls in AdS/CFT. We also estimate the value of the surface tension for the ball. The solution displays a number of peculiarities, most notably a non-trivial curvature of the boundary geometry, as well as other properties associated to the vanishing deconfinement temperature of the set up. We discuss how these features are related to specific physics at the infrared and ultraviolet boundaries for this solution, and should not be generic properties of plasma balls.Comment: 23 pages, 3 figure

On soft capacities, quasi-stationary distributions and the pathwise approach to metastability

Motivated by the study of the metastable stochastic Ising model at subcritical temperature and in the limit of a vanishing magnetic field, we extend the notion of ($\kappa$, $\lambda$)-capacities between sets, as well as the associated notion of soft-measures, to the case of overlapping sets. We recover their essential properties, sometimes in a stronger form or in a simpler way, relying on weaker hypotheses. These properties allow to write the main quantities associated with reversible metastable dynamics, e.g. asymptotic transition and relaxation times, in terms of objects that are associated with two-sided variational principles. We also clarify the connection with the classical "pathwise approach" by referring to temporal means on the appropriate time scale.Comment: 29 pages, 1 figur

BPS Solutions in AdS/CFT

We study a class of exact supersymmetric solutions of type IIB Supergravity. They have an SO(4) x SU(2) x U(1) isometry and preserve generically 4 of the 32 supersymmetries of the theory. Asymptotically AdS_5 x S^5 solutions in this class are dual to 1/8 BPS chiral operators which preserve the same symmetries in the N=4 SYM theory. We analyse the solutions to these equations in a large radius asymptotic expansion: they carry charges with respect to two U(1) KK gauge fields and their mass saturates the expected BPS bound. We also show how the same formalism is suitable for the description of the AdS_5 x Y^{p,q} geometries and a class of their excitations.Comment: 5 pages, Latex, uses w-art class (included). To appear in the Proceedings of the RTN workshop "ForcesUniverse", Naples, October 9-13, 200

The improvement of the sanitation services in Moshi (Tanzania)

Tanzania has created, since the mid-90s, an original institutional framework for water and sanitation management made of a mix of decentralized initiative and public control. This article presents this framework and its functioning on sanitation issues in the town of Moshi, a medium-sized town located on the south slopes of the Kilimanjaro Mountain. Findings are coming from a pluridisciplinary franco-tanzanian research program dedicated to these issues in 2002 and 2003. The objective of this work was to identify - through a regulation analysis of the sector and an analysis of households' needs and demand - the stakeholders of the sector and to study their behaviours and their interactions. Using the output of this program first trends of policies were elaborated during a workshop held in November 2003 with all the main stakeholders who could exchange their different perceptions of the problems and their ideas to solve them.Sanitation, public policy, willingness to pay, demand, household survey

Il crocifisso ligneo di Scandolara Ravara (Cremona)

Attualmente ubicato in area periferica rispetto ai grandi centri padani il paese di Scandolara Ravara (CR) e il crocifisso medievale conservato nella chiesa parrocchiale hanno vissuto un silenzio storiografico raramente interrotto. Partendo da un quadro più ampio sulla scultura lignea di XII-XIII secolo, l’articolo intende gettare nuova luce sul crocifisso inserendolo all’interno di un sistema di relazioni culturali più ampio con il tentativo di comprendere il rapporto tra i grandi cantieri di fine XII-XIII secolo delle città vicine (Cremona, Parma, Fidenza) e modelli di immagine d’oltralpe.Actually in a fringe area towards the important cities of the Po Valley, Scandolara Ravara (CR) and the medieval crucifix preserved in the parish church have lived in a cone of historiography silence rarely broken. Starting from a reference frame concerning the 11-12th centuries wooden-carving, the article intends to shine a light about the crucifix, considering it in a cultural relations broader system and trying to understand the relationship between biggest 11-12th centuries construction sites of nearest cities (Cremona, Parma, Fidenza) and the french-mosan image models

Quel avenir pour les enquêtes d'évaluation monétaire de la nature?

18 pagesNational audienceC'est sur le succès de la méthode d'évaluation contingente (MEC) et sur son avenir que nous nous interrogerons dans cet article en synthétisant notamment les principaux résultats des travaux que nous avons développés depuis plusieurs années sur le sujet. Ces recherches ont mis en évidence ou reformulés des problèmes théoriques et méthodologiques qui conduisent à conclure à l'échec de la MEC (et de ses dérivées) à répondre à l'objectif qui leur est assignée. Mais cet échec pose de nouvelles questions de recherche que nous voudrions présenter ici et qui, selon la façon dont elles seront prises en charge par la communauté scientifique, déterminerons le futur de ces méthodes d'évaluation par enquête

Éthique et évaluation monétaire de l’environnement : La nature est-elle soluble dans l’utilité ?

« La nature disparaît parce qu’elle n’a pas de valeur économique », voilà l’hypothèse qui sous-tend le foisonnement récent de commandes publiques et des travaux scientifiques sur l’évaluation monétaire des biens environnementaux. Posée en ces termes, l’interrogation n’est pas de savoir si la nature a une valeur économique ou non, mais de mesurer celle-ci. La question serait donc technique. Or, il se pourrait bien que le problème essentiel posé aux méthodes d’évaluation monétaire de la nature soit philosophique, et relatif au type de lien qu’entretiennent les hommes avec leur milieu. C’est en effet ce que montre l’analyse des fondements théoriques de la méthode d’évaluation contingente. Entrer dans cette « machinerie » issue de la science économique nous apprend que pour qu’il y ait évaluation, il faut qu’il y ait possibilité de substitution : il faut que les individus soient en capacité de substituer un état de l’environnement à leur revenu monétaire et qu’ils soient donc dénués de comportements moraux qui pourraient briser ces possibilités de substitution. Cette hypothèse étant contredite par de nombreux travaux en éthique de l’environnement, se pose alors la question du sens à donner aux chiffres généralement interprétés comme des évaluations monétaires de biens naturels."The nature disappears because it has no economic value", here is the hypothesis that underlies the recent profusion of state commissions and scientific works on the monetary evaluation of environmental goods. Put in these terms, the interrogation is not to know if the nature has an economic value or not, but to measure this one. The scientific questions linked to these methods are therefore usually defined as technical issues, when their main problem may be philosophical, related to the type of moral link that exists between humans and their environment. The analysis of the theoretical foundations of the contingent valuation method indeed shows that to value environmental goods the individuals have to be in capacity to substitute a state of the environment for their monetary income. They therefore cannot have moral links with these goods that could prevent possibilities of substitution. This hypothesis is however contested by numerous works on environmental ethics that finally raise the question of the signification of the numbers usually interpreted as monetary values of environmental goods