Angular Momentum Evolution of Stars in the Orion Nebula Cluster

(Abridged) We present theoretical models of stellar angular momentum evolution from the Orion Nebula Cluster (ONC) to the Pleiades and the Hyades. We demonstrate that observations of the Pleiades and Hyades place tight constraints on the angular momentum loss rate from stellar winds. The observed periods, masses and ages of ONC stars in the range 0.2--0.5 M$_\odot$, and the loss properties inferred from the Pleiades and Hyades stars, are then used to test the initial conditions for stellar evolution models. We use these models to estimate the distribution of rotational velocities for the ONC stars at the age of the Pleiades (120 Myr). The modeled ONC and observed Pleiades distributions of rotation rates are not consistent if only stellar winds are included. In order to reconcile the observed loss of angu lar momentum between these two clusters, an extrinsic loss mechanism such as protostar-accretion disk interaction is required. Our model, which evolves the ONC stars with a mass dependent saturation threshold normalized such that $\omega_{crit} = 5.4 \omega_\odot$ at 0.5 \m, and which includes a distribution of disk lifetimes that is uniform over the range 0--6 Myr, is consistent with the Pleiades. This model for disk-locking lifetimes is also consistent with inferred disk lifetimes from the percentage of stars with infrared excesses observed in young clusters. Different models, using a variety of initial period distributions and different maximum disk lifetimes, are also compared to the Pleiades. For disk-locking models that use a uniform distribution of disk lifetimes over the range 0 to $\tau_{max}$, the acceptable range of the maximum lifetime is $3.5 < \tau_{max} < 8.5$ Myr.Comment: 21 pages, 7 figures, submitted to Ap

The Rise and Effect Of Social Organizations in Louisiana During Reconstruction

In treating this topic, The Rise And Effect of Socials Organizations in Louisiana During Reconstruction, the author\u27s object is to show how these organizations come into existence. Their disrupture of social order in the State, and their permanent effect on the social thought of Louisiana. There were hundreds of organizations and societies in Louisiana, but they were either absorbed in the larger associations or were identical in purpose and effect. The organizations which were most influential in the change of social though in regard to the Negro in Louisiana, are herein treate

‘Back to our Roots?’ Re-visiting psychoanalytically-informed baby and young child observation in the education of student social workers

While there is a well-established literature on psychoanalytically-informed baby and young child observation in social work education, little has been published recently. This paper reviews the rationale for its use, evaluating its impact on students’ learning in the light of contemporary policy and practice contexts facing social work education. Analysis of feedback gained from a recent cohort, identifies three ways in which learning through baby and young child observation contributes: firstly, students encounter and learn about the complexity of child development from the direct experience of observing and secondly, observing facilitates the development of important skills for practice; students’ ‘use of self’. Thirdly, through observing, students describe how they develop the capacity to take-up and sustain a professional role. Well-structured teaching and learning through observation is therefore shown to provide a rigorous, theoretically- grounded contribution to the training of university-based social work students entering this complex and challenging professional field

Benzene formation in the inner regions of protostellar disks

Benzene (c-C6H6) formation in the inner 3 AU of a protostellar disk can be efficient, resulting in high abundances of benzene in the midplane region. The formation mechanism is different to that found in interstellar clouds and in protoplanetary nebulae, and proceeds mainly through the reaction between allene (C3H4) and its ion. This has implications for PAH formation, in that some fraction of PAHs seen in the solar system could be native rather than inherited from the interstellar medium.Comment: 9 pages, 2 colour figures, to be published in the Astrophysical Journal Letter

Roughness of sandstone fracture surfaces: Profilometry and shadow length investigations

The geometrical properties of fractured sandstone surfaces were studied by measuring the length distribution of the shadows appearing under grazing illumination. Three distinct domains of variation were found: at short length scales a cut-off of self-affinity is observed due to the inter-granular rupture of sandstones, at long length scales, the number of shadows falls off very rapidly because of the non-zero illumination angle and of the finite roughness amplitude. Finally, in the intermediate domain, the shadow length distribution displays a power law decrease with an exponent related to the roughness exponent measured by mechanical profilometry. Moreover, this method is found to be more sensitive to deviations from self-affinity than usual methods

Les clusters tourisme : quels enjeux pour les systèmes d’information ? Une analyse exploratoire

National audienc

La mise en tourisme et le développement local par la création d’une atmosphère gastronomique. Analyse à partir du cas de Vonnas

Vonnas montre l’exemple d’une mise en tourisme et d’une dynamique de développement local portées par un cuisinier entrepreneur, Georges Blanc, qui ancre son parcours économique et son orientation culinaire dans une longue tradition familiale. La stratégie de développement socioéconomique et culturelle du cuisinier, fondée sur l’innovation entrepreneuriale et sur la créativité culinaire, a conduit à l’émergence d’un lieu caractérisé par une singulière concentration d’activités orientées vers la gastronomie : le Village Gourmand. Fondée sur l’identité bressanne, cette atmosphère gastronomique favorise la mise en place des conditions nécessaires au développement local. Georges Blanc va engager une théâtralisation de cette atmosphère gastronomique afin de la rendre pleinement accessible et compréhensible par les touristes. Cette théâtralisation autorise la co-production de l’expérience touristique et, finalement, de la destination touristique gourmande

Le concept de cluster est-il soluble dans le tourisme ?

Dans les approches scientifiques, le concept de cluster (grappe) met en évidence, d’une part, le rôle des proximités organisationnelles, construites à partir des proximités spatiales dans la dynamique de compétitivité des destinations touristiques. D’autre part, des clusters tourisme se développent partout dans le monde. Or, le concept de cluster, tel que proposé par Porter (1998), émane de l’économie industrielle.L’enjeu de cet article consiste donc à montrer que le simple transfert d’un outil scientifique élaboré dans le contexte industriel au management des destinations touristiques pose problème. Il doit être enrichi pour comprendre les dynamiques de développement touristique local et acquérir plus d’efficacité opérationnelle. Trois axes de réflexion théorique, mais inspirés par des études de cas rencontrées dans différents travaux de recherche, sont proposés pour interroger les analyses des clusters tourisme. Il convient en effet de prendre en compte trois dimensions spécifiques qui seront abordées à partir du processus de coproduction inhérent à l’activité touristique, des dynamiques de proximités singulières dans ce champ du tourisme et des caractéristiques de l’encastrement des activités touristiques dans le territoire. Enfin, les auteurs proposent un modèle de cluster plus adapté aux destinations touristiques

Management à distance et santé au travail : Quels sont les impacts de l’éloignement et de la méconnaissance du travail réel ?

Cette recherche explore deux cas d’entreprises développant un management à distance. On montrera que ce management focalisé essentiellement sur un contrôle formel de l’activité créé des distorsions entre les représentations du management et celles des salariés. Or, les salariés étant confrontés à une forte incertitude lors de périodes de mutations exigeantes en termes de management des ressources humaines, ces distorsions génèrent chez eux perte de confiance, désengagement, stress et désespoir, qui peuvent avoir un impact important sur leur santé