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Abstract: We show that type I string theory compactified in four dimensions in the presence of constant internal magnetic fields possesses supersymmetric vacua, in which all Kähler class and complex structure closed string moduli are fixed. Furthermore, their values can be made arbitrarily large by a suitable tuning of the quantized magnetic fluxes. We present an explicit example for the toroidal compactification on and discuss Calabi–Yau generalizations. This mechanism can be complementary to other stabilization methods using closed string fluxes but has the advantage of having an exact string description and thus a validity away from the low-energy supergravity approximation. Moreover, it can be easily implemented in constructions of string models based on intersecting D-branes. [Copyright &y& Elsevier]

Background. – Fetal alcohol syndrome (FAS) is a major problem in the Reunion Island and the Public Health Authorities decided to determine its prevalence in their medico-social centers on 31 December 1996.Material and methods. – A questionnaire was etablished to identify affected patients in the 20 medico-social centers in charge of 1320 children. Eighty-eight children were selected and 87 could be analyzed.Results. – Sixty-four of 87 (76.3%) were FAS and 23 of 87 (23.7%) had closely alcohol-related diseases. The prevalence was between 7.1 and 14.1% and lower than expected from available data.Conclusion. – The study allowed to precise the social and familial factors predisposing to alcohol addiction during pregnancy. A TV prevention message will be broadcasted after this study. [ABSTRACT FROM AUTHOR]

Abstract: Nonlinear supersymmetry is used to compute the general form of the effective D-brane action in type I string theory compactified to four dimensions in the presence of internal magnetic fields. In particular, the scalar potential receives three contributions: (1) a nonlinear part of the D-auxiliary component, associated to the Dirac–Born–Infeld action; (2) a Fayet–Iliopoulos (FI) D-term with a moduli-dependent coefficient; (3) a D-auxiliary independent (but moduli dependent) piece from the D-brane tension. Minimization of this potential leads to three general classes of vacua with moduli stabilization: (i) supersymmetric vacua allowing in general FI terms to be cancelled by non-trivial vacuum expectation values (VEV''s) of charged scalar fields; (ii) anti-de Sitter vacua of broken supersymmetry in the presence of a non-critical dilaton potential that can be tuned at arbitrarily weak string coupling; (iii) if the dilaton is fixed in a supersymmetric way by three-form fluxes and in the absence of charged scalar VEV''s, one obtains non-supersymmetric vacua with positive vacuum energy. [Copyright &y& Elsevier]

Abstract: We analyze a class of dual pairs of heterotic and type I models based on freely-acting orbifolds in four dimensions. Using the adiabatic argument, it is possible to calculate non-perturbative contributions to the gauge coupling threshold corrections on the type I side by exploiting perturbative calculations on the heterotic side, without the drawbacks due to twisted moduli. The instanton effects can then be combined with closed-string fluxes to stabilize most of the moduli fields of the internal manifold, and also the dilaton, in a racetrack realization of the type I model. [Copyright &y& Elsevier]

We study mediation of supersymmetry breaking in the bulk, in models with primordial supersymmetry breaking on D-branes at the string scale, in the TeV region. We compute the gravitino and scalar masses up to one-loop level, as well as the radion coupling to matter. We find that the latter mediates a model independent force at submillimeter distances that can be tested in micro-gravity experiments for any dimensionality of the bulk. In the case of two large dimensions, our type I string framework provides an example which allows to stabilize the radion potential and determine the desired hierarchy between the string and Planck scales. [Copyright &y& Elsevier]