Bandwidth smearing in optical interferometry: Analytic model of the transition to the double fringe packet

Bandwidth smearing is a chromatic aberration due to the finite frequency bandwidth. In long-baseline optical interferometry terms, it is when the angular extension of the source is greater than the coherence length of the interferogram. As a consequence, separated parts of the source will contribute to fringe packets that are not fully overlapping; it is a transition from the classical interferometric regime to a double or multiple fringe packet. While studied in radio interferometry, there has been little work on the matter in the optical, where observables are measured and derived in a different manner, and are more strongly impacted by the turbulent atmosphere. We provide here the formalism and a set of usable equations to model and correct for the impact of smearing on the fringe contrast and phase, with the case of multiple stellar systems in mind. The atmosphere is briefly modeled and discussed.Comment: To appear in the proceedings of the 2012 SPIE Conference "Astronomical Telescopes and Instrumentation" (9 pages, 3 figures

Cross-validating administrative and survey datasets through microsimulation and the assessment of a tax reform in Luxembourg

Using EUROMOD, we cross-validate two types of micro-data presently available in the Grand-Duchy of Luxembourg, administrative data on one hand and survey data on the other hand. While administrative data, extracted from the recently implemented Social Security Data Warehouse, contain information of the whole population of Luxembourg (449,000 observations) in 2003, survey data, extracted from the Luxembourg household panel PSELL3/EU-SILC for 2004 (incomes from 2003), is a representative sample of around 3,600 private households (9,800 individuals) living in Luxembourg with detailed information on incomes, household structure and other socio-economic dimensions. As a concrete application of this cross-validation, we analyze the 2001-2002 tax reform in Luxembourg. The main aspects of this reform are the reduction of the number of the tax brackets and the fall of the maximal marginal tax rate (from 46% in 2000 to 42% in 2001 and to 38% in 2002). The distributional effects of the tax reform are measured in terms of losers and winners, change in inequalities and poverty rates. The results issued from different types of input data are compared for cross-validation and allow us to emphasize methodological difficulties as well as to underline the advantages and limitations of each dataset.EUROMOD ; Microsimulation ; Tax reform ; Validation

Histoire globale, mondialisations et capitalisme

International audienceEn quoi l'actuel renouveau de l'Asie plonge-t-il ses racines dans une " longue durée " globale ? Quelle est la nature des changements structurels accompagnant la croissance démographique, le développement de l'État et du commerce, l'accumulation localisée des richesses et du savoir ? Comment rendre intelligibles une expansion géographique des flux d'échange et le déploiement parfois concomitant du capitalisme à l'échelle nationale, puis mondiale ? Pour la première fois en France, un ouvrage réunit anthropologues, économistes, politologues, sociologues et historiens pour répondre à ces questions et esquisser les grandes lignes d'un nouveau programme de recherche : l'Histoire Globale. Celle-ci recouvre d'abord une analyse du rôle crucial du monde non européen dans l'histoire de l'humanité pour sortir enfin d'une démarche trop eurocentrée. Elle constitue ensuite un profond renouvellement de l'analyse en termes de système-monde, au-delà des œuvres incontournables de Braudel et de Wallerstein. Elle inclut enfin l'analyse comparative des processus de mondialisation. Le pari de cet ouvrage est de présenter l'histoire Globale à partir de textes classiques ou inédits de quelques-uns de ses auteurs les plus marquants. Un prologue propose une synthèse de ses problématiques et recherches les plus caractéristiques, en soulignant leurs enjeux épistémologiques pour les sciences sociales. Les contributions de Beaujard, Bentley, Goody, Chase-Dunn et Hall éclairent les processus pluriséculaires d'intégration intercontinentale ; celles d'Aglietta, Arrighi et Silver, Gills et Denemark, Wallerstein abordent la naissance, le développement et les crises du capitalisme global ; les écrits de Berger, Goldstone, Norel, Pomeranz, Wong analysent les liens entre les épisodes de croissance et de créativité culturelle récurrents (ou " efflorescences "), et les processus de mondialisation

Temperature dependence of exciton recombination in semiconducting single-wall carbon nanotubes

We study the excitonic recombination dynamics in an ensemble of (9,4) semiconducting single-wall carbon nanotubes by high sensitivity time-resolved photo-luminescence experiments. Measurements from cryogenic to room temperature allow us to identify two main contributions to the recombination dynamics. The initial fast decay is temperature independent and is attributed to the presence of small residual bundles that create external non-radiative relaxation channels. The slow component shows a strong temperature dependence and is dominated by non-radiative processes down to 40 K. We propose a quantitative phenomenological modeling of the variations of the integrated photoluminescence intensity over the whole temperature range. We show that the luminescence properties of carbon nanotubes at room temperature are not affected by the dark/bright excitonic state coupling

Refined masses and distance of the young binary Haro 1-14 C

We aim to refine the dynamical masses of the individual component of the low-mass pre-main sequence binary Haro 1-14 C. We combine the data of the preliminary orbit presented previously with new interferometric observations obtained with the four 8m telescopes of the Very Large Telescope Interferometer. The derived masses are M_a=0.905\pm0.043\,\Msun and M_b=0.308\pm0.011\,\Msun for the primary and secondary components, respectively. This is about five times better than the uncertainties of the preliminary orbit. Moreover, the possibility of larger masses is now securely discarded. The new dynamical distance, $d=96\pm\,9\,$pc, is smaller than the distance to the Ophiuchus core with a significance of $2.6\,\sigma$. Fitting the spectral energy distribution yields apparent diameters of \phi_a=0.13\pm0.01\mas and \phi_b=0.10\pm0.01\mas (corresponding to \Ra=1.50\,\Rsun and \Rb=1.13\,\Rsun) and a visual extinction of $A_v\approx1.75$. Although the revised orbit has a nearly edge-on geometry, the system is unlikely to be a long-period eclipsing binary. The secondary in Haro~1-14C is one of the few low-mass, pre-main sequence stars with an accurately determined dynamical mass and distance