Social Choice with Analytic Preferences

A social welfare function is a mapping from a set of profiles of individual preference orderings to the set of social orderings of a universal set of alternatives. A social choice correspondence specifies a nonempty subset of the agenda for each admissible preference profile and each admissible agenda. We provide examples of economic and political preference domains for which the Arrow social welfare function axioms are inconsistent, but whose choice-theoretic counterparts (with nondictatorship strengthened to anonymity) yield a social choice correspondence possibility theorem when combined with a natural agenda domain. In both examples, agendas are compact subsets of the nonnegative orthant of a multidimensional Euclidean space. In our first possibility theorem, we consider the standard Euclidean spatial model used in many political models. An agenda can be interpreted as being the feasible vectors of public goods given the resource constraints faced by a legislature. Preferences are restricted to be Euclidean spatial preferences. Our second possibility theorem is for economic domains. Alternatives are interpreted as being vectors of public goods. Preferences are monotone and representable by an analytic utility function with no critical points. Convexity of preferences can also be assumed. Many of the utility functions used in economic models, such as Cobb-Douglas and CES, are analytic. Further, the set of monotone, convex, and analytic preference orderings is dense in the set of continuous, monotone, convex preference orderings. Thus, our preference domain is a large subset of the classical domain of economic preferences. An agenda can be interpreted as the set of feasible allocations given an initial resource endowment and the firms' production technologies. To establish this theorem, an ordinal version of the Analytic Continuation Principle is developed.

Les enjeux du Protocole facultatif se rapportant au Pacte international relatif aux droits économiques, sociaux et culturels

L’adoption par l’Assemblée générale des Nations unies, le 10 décembre 2008, du Protocole facultatif se rapportant au Pacte international relatif aux droits économiques, sociaux et culturels, marque une avancée importante pour la protection internationale des droits économiques, sociaux et culturels. Fruit de longues années de débats et de controverses, le Protocole institue un système de communications individuelles et interétatiques devant le Comité des droits économiques, sociaux et culturels. Cet instrument constitue ainsi un véritable démenti à la thèse largement répandue selon laquelle les droits économiques, sociaux et culturels ne seraient pas d’authentiques droits de l’homme au même titre que les droits civils et politiques et, par conséquent, seraient non susceptibles d’être contrôlées par voie de communications. Il n’en demeure pas moins que le rétablissement de l’égalité entre droits civils et politiques et droits économiques, sociaux et culturels, reste à conquérir face à un contexte socio-économique global relativement indifférent à une prise en compte des droits économiques, sociaux et culturels. La mise en oeuvre du Protocole sera également confrontée aux obstacles inhérents cette fois à la spécificité du droit international des droits de l’homme, droit dans lequel l’Etat est juge et partie de sa contribution à leur protection. En dépit de ces difficultés, il est à espérer que son application pourra améliorer, même modestement, les conditions de vie de milliers d’individus

Modeling the HD32297 Debris Disk with Far-IR Herschel Data

HD32297 is a young A-star (~30 Myr) 112 pc away with a bright edge-on debris disk that has been resolved in scattered light. We observed the HD32297 debris disk in the far-infrared and sub-millimeter with the Herschel Space Observatory PACS and SPIRE instruments, populating the spectral energy distribution (SED) from 63 to 500{\mu}m. We aimed to determine the composition of dust grains in the HD32297 disk through SED modeling, using geometrical constraints from the resolved imaging to break degeneracies inherent in SED modeling. We found the best fitting SED model has 2 components: an outer ring centered around 110 AU, seen in the scattered light images, and an inner disk near the habitable zone of the star. The outer disk appears to be composed of grains > 2{\mu}m consisting of silicates, carbonaceous material, and water ice with an abundance ratio of 1:2:3 respectively and 90% porosity. These grains appear consistent with cometary grains, implying the underlying planetesimal population is dominated by comet-like bodies. We also discuss the 3.7{\sigma} detection of [C II] emission at 158{\mu}m with the Herschel PACS Spectrometer, making HD32297 one of only a handful of debris disks with circumstellar gas detected.Comment: 11 pages, 4 figures, accepted for publication in The Astrophysical Journa

Radiation-hydrodynamics simulations of surface convection in low-mass stars: connections to stellar structure and asteroseismology

Radiation-hydrodynamical simulations of surface convection in low-mass stars can be exploited to derive estimates of i) the efficiency of the convective energy transport in the stellar surface layers; ii) the convection-related photometric micro-variability. We comment on the universality of the mixing-length parameter, and point out potential pitfalls in the process of its calibration which may be in part responsible for the contradictory findings about its variability across the Hertzsprung-Russell digramme. We further comment on the modelling of the photometric micro-variability in HD49933 - one of the first main COROT targets.Comment: 6 pages, 5 figures, Proceedings paper of IAU Symposium 25