AMD-stability and the classification of planetary systems

We present here in full detail the evolution of the angular momentum deficit (AMD) during collisions as it was described in (Laskar, PRL,2000). Since then, the AMD has been revealed to be a key parameter for the understanding of the outcome of planetary formation models. We define here the AMD-stability criterion that can be easily verified on a newly discovered planetary system. We show how AMD-stability can be used to establish a classification of the multiplanet systems in order to exhibit the planetary systems that are long-term stable because they are AMD-stable, and those that are AMD-unstable which then require some additional dynamical studies to conclude on their stability. The AMD-stability classification is applied to the 131 multiplanet systems from The Extrasolar Planet Encyclopaedia database (exoplanet.eu) for which the orbital elements are sufficiently well known.Comment: 18 pages, 13 figures, A&A in pres

AMD-stability in presence of first order Mean Motion Resonances

The AMD-stability criterion allows to discriminate between a-priori stable planetary systems and systems for which the stability is not granted and needs further investigations. AMD-stability is based on the conservation of the Angular Momentum Deficit (AMD) in the averaged system at all orders of averaging. While the AMD criterion is rigorous, the conservation of the AMD is only granted in absence of mean-motion resonances (MMR). Here we extend the AMD-stability criterion to take into account mean-motion resonances, and more specifically the overlap of first order MMR. If the MMR islands overlap, the system will experience generalized chaos leading to instability. The Hamiltonian of two massive planets on coplanar quasi-circular orbits can be reduced to an integrable one degree of freedom problem for period ratios close to a first order MMR. We use the reduced Hamiltonian to derive a new overlap criterion for first order MMR. This stability criterion unifies the previous criteria proposed in the literature and admits the criteria obtained for initially circular and eccentric orbits as limit cases. We then improve the definition of AMD-stability to take into account the short term chaos generated by MMR overlap. We analyze the outcome of this improved definition of AMD-stability on selected multi-planet systems from the Extrasolar Planets Encyclopeadia.Comment: Accepted by A and A 07/10/1

Worker information and firm disclosure: Analysis on French linked employer-employee data

Information disclosure requirements significantly increased in French listed companies in the early 2000s, converging toward the U.S./U.K. stock market standards. Following the burgeoning literature on relations between corporate governance and labor, we investigate the consequences of this process regarding worker information: does more information for shareholders mean more information for workers? We take advantage of a French (representative) establishment survey that generates linked 'employer–employee' data at two points in time, 1998 and 2004. Our results strongly suggest that worker information has improved in listed companies but not in private ones, as an externality of the financialization process. We find however that this extra information is only partially correlated with greater employee satisfaction, as measured through the perception of fair recognition by supervisors.information sharing, firm disclosure, corporate governance, job satisfaction, linked employer employee data

Real-time tracking of 3D elastic objects with an RGB-D sensor

This paper presents a method to track in real-time a 3D textureless object which undergoes large deformations such as elastic ones, and rigid motions, using the point cloud data provided by an RGB-D sensor. This solution is expected to be useful for enhanced manipulation of humanoid robotic systems. Our framework relies on a prior visual segmentation of the object in the image. The segmented point cloud is registered first in a rigid manner and then by non-rigidly fitting the mesh, based on the Finite Element Method to model elasticity, and on geometrical point-to-point correspondences to compute external forces exerted on the mesh. The real-time performance of the system is demonstrated on synthetic and real data involving challenging deformations and motions

Tracking Fractures of Deformable Objects in Real-Time with an RGB-D Sensor

This paper introduces a method able to track in real-time a 3D elastic deformable objects which undergo fractures, using the point cloud data provided by an RGB-D sensor. Our framework relies on a prior visual segmentation of the object in the image. The segmented point cloud is registered by non-rigidly fitting the mesh, based on the Finite Element Method to physically model elasticity, and on geometrical point-to-point correspondences to compute external forces exerted on the mesh. Fractures are handled by processing the stress tensors computed on the mesh of the FEM model, in order to detect fracturable nodes. Local remeshing around fracturable nodes is then performed to propagate the fracture. The real-time performance of the system is demonstrated on real data involving various deformations and fractures

Marché boursier et gestion de l'emploi : analyse sur données d'entreprises françaises

URL des Documents de travail :http://ces.univ-paris1.fr/cesdp/CESFramDP2007.htmDocuments de travail du Centre d'Economie de la Sorbonne 2007.41 - ISSN : 1955-611XThis article examines the influence of equity capital ownership on human resource management practices. The empirical analysis uses the 2004-2005 Workplace Industrial Relations Survey (REPONSE survey), based on a sample of 2,930 establishments with 20 workers or more, representative of the French private sector. Econometric analysis confirms the importance of equity ownership as a determinant of employment practices, considering labour mobilisation contracts (agency work, short term contracts and sub-contracting), wage policy (level of remuneration and use of variable pay), changes in the staff size and training expenses.Cet article étudie l'influence de la structure de propriété du capital social (cotation et identité des actionnaires) sur la gestion de l'emploi. Nous utilisons l'enquête REPONSE 2004-2005, fondée sur un échantillon de 2 930 établissements de 20 salariés et plus, représentatif du secteur marchand français. L'analyse économétrique confirme l'importance de la propriété comme déterminant de la gestion de l'emploi, que ce soit en termes de formes de mobilisation du travail (recours à l'intérim, aux CDD et à la sous-traitance), de politique salariale (niveau des rémunérations et usage de primes), de variation d'effectifs ou de formation

Tracking an elastic object with an RGB-D sensor for a pizza chef robot

This paper presents a method to track in real-time a 3D object which undergoes large deformations such as elastic ones, and fast rigid motions, using the point cloud data provided by a RGB-D sensor. This solution would contribute to robotic humanoid manipulation purposes. Our framework relies on a prior visual segmentation of the object in the image. The segmented point cloud is then registered first in a rigid manner and then by non-rigidly fitting the mesh, based on the Finite Element Method to model elasticity and on geometrical point-to-point correspondences to compute external forces exerted on the mesh. The real-time performance of the system is demonstrated on real data involving challenging deformations and motions, for a pizza dough to be ideally manipulated by a chef robot

The Influence of Stock Market Listing on Human Resource Managment: Evidence for France and Britain

We use data from REPONSE 2004 and WERS 2004 to analyse whether approaches to HRM differ according to whether an establishment is part of a company with a stock exchange listing. In both countries we find that listing is positively associated with teamworking and performance-related pay, while in France, but not in Britain, it is also linked to worker autonomy and training. Our findings are inconsistent with the claim that shareholder pressure operates as a constraint on the adoption of high-performance workplace practices. The pattern is similar in the two countries, but with a slightly stronger tendency for listing to be associated with high-performance workplace practices in France.corporate governance, human resource management, employment relations

Marché boursier et gestion de l'emploi : analyse sur données d'entreprises françaises

Cet article étudie l'influence de la structure de propriété du capital social (cotation et identité des actionnaires) sur la gestion de l'emploi. Nous utilisons l'enquête REPONSE 2004-2005, fondée sur un échantillon de 2 930 établissements de 20 salariés et plus, représentatif du secteur marchand français. L'analyse économétrique confirme l'importance de la propriété comme déterminant de la gestion de l'emploi, que ce soit en termes de formes de mobilisation du travail (recours à l'intérim, aux CDD et à la sous-traitance), de politique salariale (niveau des rémunérations et usage de primes), de variation d'effectifs ou de formation.Gouvernance d'entreprise, propriété sociale, gestion de l'emploi.