A Scaling Theory of the Competition between Interdiffusion and Cross-Linking at Polymer Interfaces

We study theoretically situations where competition arises between an interdiffusion process and a cross-linking chemical reaction at interfaces between pieces of the same polymer material. An example of such a situation is observable in the formation of latex films, where, in the presence of a cross-linking additive, colloidal polymer particles initially in suspension come at contact as the solvent evaporates, and, optimally, coalesce into a continuous coating. We considered the low cross-link density situation in a previous paper (A. Aradian, E. Raphael, P.-G. de Gennes, Macromolecules 33, 9444 (2000)), and presented a simple control parameter that determines the final state of the interface. In the present article, with the help of simple scaling arguments, we extend our description to higher cross-link densities. We provide predictions for the strength of the interface in different favorable and unfavorable regimes, and discuss how it can be optimized.Comment: 19 pages, 5 figures. To appear in Macromolecule

Assessing the Interaction between Real Estate and Equity in Households Portfolio Choice

In this paper, we provide a new empirical analysis of the dynamic portfolio decisions of households by simultaneously considering their stock market participation and home tenure choices. There is already a huge body of literature on housing status (own/rent) decisions and many contributions doc- umented the low stock market participation rate of US households. Although some papers evidenced that the home status (modeled as an exogenous variable) has an impact on the stock proportion in portfolio, our paper is the …rst one to allow both decisions (home and stock) to be simultaneous and endogenous. We estimate a dynamic bivariate logistic panel data model on Panel Study of income Dynamics data from 1999 to 2007 controlling for sample selection bias and time-invariant unobserved heterogeneity. We …rst evidence that our original joint setup outperforms a standard one (with two distinct equations for stock holdings and for home tenure), i.e. marginal odds ratios are signi…cant. Using these estimates, we are able to simulate individual paths of stock and home equity positions over the life cycle according to households attributes. Ceteris Paribus, we show that households taking positions in one asset (home or stock) encounter a positive position in the other asset at an earlier stage in their life cycle, i.e. some households appear to be locked in a no-stock-and-renter position.Housing, Stock market participation, Portfolio choices, Panel Data

Is Archaeology Destructive or are Archaeologists Self-Destructive

The conducting of archaeological excavations for the purpose of research without the justification of eminent destruction is often referred to, in cultural resource management literature and elsewhere, as a destructive practice- one to be avoided whenever possible. The following pages discuss the validity of a such deferral approach to archaeological research both in reference to resource conservation and to understanding the past

Flow-injection of branched polymers inside nanopores

Flexible chains (linear or branched) can be forced to enter into a narrow capillary by using a hydrodynamic flow. Here, we correct our earlier description of this problem by considering the progressive nature of the suction process. We find that the critical current for penetration, $J\_c$, is controlled by the entry of a single blob of the capillary size, and that its scaling structure is the same for branched and linear chains.Comment: Submitted to Europhysics Letter

Politiques publiques en France : présentation

L'analyse des politiques publiques peut-elle nous aider à comprendre les transformations qui affectent le système politique français depuis les années 1980 ? Telle est la question qui est à l'origine de ce numéro de la Revue française de science politique. Il ne s'agit évidemment pas de proposer une vue complète des travaux de recherche relevant de cette approche en France, aujourd'hui. En revanche, les cinq articles présentés ici constituent une bonne illustration de l'apport de l'analyse des politiques à l'étude du politique. [Premier paragraphe

Organiser la documentation scientifique en entreprise: enjeux, méthodes, outils : le cas Kejako

La société Kejako est active dans le domaine de l’ophtalmologie et en particulier dans la recherche, le développement et la commercialisation de dispositifs médicaux liés à ce domaine. Toutefois, depuis sa création, l’entreprise a accumulé une masse documentaire importante, et s’interrogeait sur la mise en valeur de ses documents, mise en valeur d’autant plus importante qu’elle constitue une fenêtre sur les activités de Kejako. De plus, face à la masse documentaire utilisée et produite, les procédures originellement mises en place commençaient à atteindre des limites quant à leur efficacité, notamment en ce qui concernait la recherche documentaire. Notre tâche a donc consisté à évaluer l’ensemble des documents de Kejako, puis à proposer non seulement une solution remplissant l’exigence de mise en valeur des documents, mais également celle de gestion numérique des documents et un ensemble de procédures permettant une visibilité accrue sur l’information1. Nous avons commencé par réaliser un état des lieux afin d’obtenir une vue d’ensemble sur les activités et pratiques documentaires de Kejako, puis nous avons proposé un système de classification et d’identification des documents afin de faciliter leur recherche dans les interfaces utilisées par les membres de la société. Enfin, nous avons réalisé un benchmark afin de proposer plusieurs solutions à Monsieur David Enfrun, directeur général de Kejako, pour qu’il puisse bénéficier d’un outil adapté à ses besoins et remplissant les exigences qu’il nous avait fixées durant ce travail. De plus, nous avons également produit un guide pratique regroupant l’ensemble des actions et des procédures à entreprendre lors du traitement d’un nouveau document. Ce mémoire décrit l’ensemble des démarches, réflexions, entretiens et rencontres que nous avons entrepris pour arriver à remplir nos objectifs, et proposer un ensemble de solutions à Kejako

A rapid and low noise switch from RANS to WMLES on curvilinear grids with compressible flow solvers

International audienceA turbulent inflow for a rapid and low noise switch from RANS to Wall-Modelled LES on curvilinear grids with compressible flow solvers is presented. It can be embedded within the computational domain in practical applications with WMLES grids around three-dimensional geometries in a flexible zonal hybrid RANS/LES modelling context. It relies on a physics-motivated combination of Zonal Detached Eddy Simulation (ZDES) as the WMLES technique together with a Dynamic Forcing method processing the fluctuations caused by a Zonal Immersed Boundary Condition describing roughness elements. The performance in generating a physically-sound turbulent flow field with the proper mean skin friction and turbulent profiles after a short relaxation length is equivalent to more common inflow methods thanks to the generation of large-scale streamwise vorticity by the roughness elements. Comparisons in a low Mach-number zeropressure-gradient flat-plate turbulent boundary layer up to Reθ = 6 100 reveal that the pressure field is dominated by the spurious noise caused by the synthetic turbulence methods (Synthetic Eddy Method and White Noise injection), contrary to the new low-noise approach which may be used to obtain the low-frequency component of wall pressure and reproduce its intermittent nature. The robustness of the method is tested in the flow around a three-element airfoil with WMLES in the upper boundary layer near the trailing edge of the main element. In spite of the very short relaxation distance allowed, self-sustainable resolved turbulence is generated in the outer layer with significantly less spurious noise than with the approach involving White Noise. The ZDES grid count for this latter test case is more than two orders of magnitude lower than the Wall-Resolved LES requirement and a unique mesh is involved, which is much simpler than some multiple-mesh strategies devised for WMLES or turbulent inflow

Demain ne meurt jamais! : anticipation personnelle du futur individuel et de l'avenir collectif de jeunes québécois(es)

La multiplication des crises rend imprévisible l'avenir du monde alors que la lourdeur du modèle productif entrave les possibilités d'imaginer un monde alternatif. Au plan individuel, le nombre de trajectoires de vie possible a explosé. À travers les concepts d'individualisation, de régime d'historicité et de temporalités sociales, ce mémoire étudie la projection individuelle des jeunes québécois(es) dans le futur individuel et l'avenir collectif. Pour la cerner, j'ai réalisé quinze entrevues qualitatives auprès de quinze jeunes de profils socio-économiques variés. À l'analyse apparaît une grande variation dans la longueur des projections des jeunes qui peuvent aller d'un an à une vie entière. De même, ce qui constitue le cœur de la projection varie considérablement : équilibre entre domaines de la vie ; expériences de vie ; famille ; engagement social ; travail. Les répondant(e)s partagent un optimisme généralisé quant à leur futur personnel et considèrent avoir toutes les cartes en main pour se forger un futur à leur convenance même si deux tiers n'ont pas de plan de vie arrêté. L'horizon de la projection dans l'avenir collectif ne dépasse pas la vie humaine. Certain(e)s jeunes identifient des dimensions clefs – environnement, économie, conflit armé – qui auront un impact sur les autres facettes de l'avenir tandis que d'autres les réfléchissent en silo et font abstraction de leur interdépendance : l'utilisation incivile du cellulaire étant aussi préoccupante que la corruption ou que les changements climatiques. Deux tiers des jeunes s'attendent à une détérioration du monde, mais considèrent les menaces collectives à venir comme trop distantes spatialement et temporellement pour s'en inquiéter outre mesure. Dans la société individualiste, la promotion à l'autoréalisation est source d'angoisse pour les jeunes qui doivent renoncer à une multitude de potentialités en choisissant un programme d'étude ou un emploi. L'optimisme devant le futur personnel et l'impression d'une identité fixe dans un monde en mouvement résultent d'un sentiment de séparation du monde qui se renforce dans la société individualiste. Cette permanence semble aussi appuyer la thèse du présentisme de François Hartog (2012) soit la propension de la société contemporaine à donner plus d'importance au présent qu'au passé ou au futur.The proliferation of crises makes the future unpredictable while the cumbersome nature of the productive model hampers the possibility of imagining an alternative. At an individual level, the number of possible life trajectories has exploded. Through the concepts of individualization, regime of historicity and social temporalities, this thesis studies the individual projection of young Quebecers in the individual and the collective future. To identify it, I conducted fifteen qualitative interviews with young people of various socio-economic background. The analysis shows a great variation in the length of the projections of the young people which can go from one year to a whole life. Similarly, what constitutes the center of the projection varies considerably - balance between life dimensions ; life experiences ; family ; social engagement ; work. The young Quebecers share a general optimism and consider having everything needed to forge a personal future at their convenience even though ten of them do not yet have a detailed life plan. The horizon of projection into the common future does not go beyond the length of human life. Some young people identify key dimensions – environment, economy, armed conflict – that will impact the future while others reflect them separately and disregard their interdependence. For example, the uncivil use of the cell phone seems as worrying as political corruption or climate change. Two thirds of the participants expect a deterioration of the world, but consider the threats too distant spatially and temporally to worry about it beyond measure. In the individualistic society, promotion of self-realization is a source of anguish for young people who have to give up a multitude of potentialities presented to them during childhood when choosing a curriculum or a job. Secondly, optimism about personal future and the impression of a fixed identity in a world in motion are the result of a feeling of separation from the world which is strengthened in the individualistic society. The perceived permanence also seems to support the hypothesis of François Hartog's presentism (2012), namely the propensity of contemporary society to give more importance to the present than to the past or the future

Vibration analysis of cable-driven parallel robots based on the dynamic stiffness matrix method

This paper focuses on the vibration analysis of Cable-Driven Parallel Robots (CDPRs). An oscillating model of CDPRs able to capture the dynamic behavior of the cables is derived using Lagrangian approach in conjunction with the Dynamic Stiffness Matrix method. Then, an original approach to analyze the modal interaction between the local cable modes and the global CDPR modes is presented. To illustrate this approach, numerical investigations and experimental analyses are carried out on a large-dimension 6-DOF suspended CDPR driven by 8 cables

Impugnação das decisões judiciais: reconstrução da relação entre recursos e ações autônomas de impugnação

Divulgação dos SUMÁRIOS das obras recentemente incorporadas ao acervo da Biblioteca Ministro Oscar Saraiva do STJ. Em respeito à Lei de Direitos Autorais, não disponibilizamos a obra na íntegra.Localização na estante: 347.955(81) E34