Accurate and realistic initial data for black hole-neutron star binaries

This paper is devoted to the computation of compact binaries composed of one black hole and one neutron star. The objects are assumed to be on exact circular orbits. Standard 3+1 decomposition of Einstein equations is performed and the conformal flatness approximation is used. The obtained system of elliptic equations is solved by means of multi-domain spectral methods. Results are compared with previous work both in the high mass ratio limit and for one neutron star with very low compactness parameter. The accuracy of the present code is shown to be greater than with previous codes. Moreover, for the first time, some sequences containing one neutron star of realistic compactness are presented and discussed.Comment: Version including the erratum to be published in Phys. Rev.

The parabolic-parabolic Keller-Segel system with critical diffusion as a gradient flow in \RR^d, d≥3d \ge 3

It is known that, for the parabolic-elliptic Keller-Segel system with critical porous-medium diffusion in dimension \RR^d, $d \ge 3$ (also referred to as the quasilinear Smoluchowski-Poisson equation), there is a critical value of the chemotactic sensitivity (measuring in some sense the strength of the drift term) above which there are solutions blowing up in finite time and below which all solutions are global in time. This global existence result is shown to remain true for the parabolic-parabolic Keller-Segel system with critical porous-medium type diffusion in dimension \RR^d, $d \ge 3$, when the chemotactic sensitivity is below the same critical value. The solution is constructed by using a minimising scheme involving the Kantorovich-Wasserstein metric for the first component and the $L^2$-norm for the second component. The cornerstone of the proof is the derivation of additional estimates which relies on a generalisation to a non-monotone functional of a method due to Matthes, McCann, & Savar\'e (2009)

Usages actuels du provençal dans la signalétique urbaine en Provence : motivations, significations et enjeux sociolinguistiques

Les années 1990-2004 ont vu se développer de façon marquante une signalétique en provençal, souvent bilingue français-provençal, dans les villes de Provence (panneaux d’entrée de communes, noms de rues et de bâtiments administratifs, plaques touristiques et historiques, etc.). Les choix linguistiques et graphiques réalisés méritent analyse : les noms des communes affichés sont souvent une re-traduction en provençal du nom français officiel lui-même adapté – souvent maladroitement – à partir du toponyme historique en provençal local, les graphies hésitent entre plusieurs normes et plusieurs langues, les lieux retenus sont souvent symboliques, etc. Cette signalétique révèle la complexité et les tensions sociolinguistiques de la situation provençale (et plus largement française), ainsi que les problèmes auxquels se heurte toute tentative de réhabilitation linguistique et culturelle en situation de minoration et de contacts de langues.From 1990 to 2004, signage in Provençal has developed considerably in Provençal cities, often bilingual (French and Provençal) (signs at the entrance of towns, street and building names, tourist information, historical plaques, etc.). Attention should be payed to linguistic and spelling choices. Town names shown on signs are often retranslations into Provençal of official French names that are themselves adaptations – often awkward – of the historical Provençal toponym; spelling hesitates between various standards and languages, the sites are often symbolic, etc. Signage thus reveals the complexity and the sociolinguistic tensions that arise from the Provençal situation (albeit the French situation), as well as problems confronting attempts to rehabilitate a linguistic and cultural minority situation in a language contact context

Discours savants, discours militants

Le texte de C. Milhé est une contribution stimulante, honnête et courageuse. Il faut en saluer la réflexivité, si précieuse et pourtant finalement si peu fréquente chez les chercheurs parce qu’elle touche fondamentalement à la définition même de la science et au statut du chercheur (Robillard, 2009). Ce texte soulève au fond deux questions : la complexité du rapport au terrain, le statut des connaissances produites. La première est à la fois d’ordre factuel (il faut comprendre un contexte dan..

Regard sur la dynamique ethno-sociolinguistique actuelle de la Provence, ou quand l’identité fait reculer la diglossie

Après un rapide historique de la situation sociolinguistique provençale, l’auteur présente les réalités langagières de la Provence. Il rappelle la situation diglossique prégnante dans ce territoire et il donne de nombreux exemples de pratiques linguistiques avant de mettre en lumière des prospectives.After a brief history of the sociolinguistic situation in Provence, the author presents the linguistic realities of the region. He recalls the diglossic situation prevalent in this territory and gives numerous examples of linguistic practices before highlighting future prospects

Integração ou discriminação da pluralidade linguística na educação de línguas e pelas línguas: uma questão crucial entre ideologia, ética e didática

ABSTRACT: In this text, the author deals with the issues of integrating or rejecting linguistic and cultural diversity in language teaching and more widely in education through languages. He presents a conception of (socio)linguistic competence elaborated out of an analysis of sociolinguistic diversity. He then compares, on the one hand, sociolinguistic practices and competences, to, on the other hand, the teaching process of desocialised and unified standard languages that were artificially elaborated to reach ideological political aims. He shows how teaching standard languages creates discriminations which are unacceptable both from an ethical and a legal points of view, and how it also creates social and educational failures. As a conclusion, he suggests pedagogical principles and pragmatic actions that could progressively and deeply integrate linguistic and cultural diversity into language teaching and a humanist education through languages. KEY-WORDS : Ideology. Linguistic discrimination. Language education. Language teaching.RESUMO: Este texto levanta a questão radical4 das implicações transversais da consideração ou, ao contrário, da rejeição da pluralidade linguística e cultural no ensino de línguas e, mais amplamente, na educação pelas línguas (COSTE, 2013). Ele apoia-se principalmente, e mais explicitamente, na questão linguística sem, no entanto, negligenciar, de maneira menos presente e menos explícita, a questão cultural e, sobretudo, intercultural. Este artigo, redigido por um especialista de dinâmicas sociolinguísticas e sociodidáticas francófonas, toma por exemplo prioritariamente o francês, mas a análise é certamente adaptável a outras línguas de difusão internacional, de escolarização e de status oficial estatal. Colocando-se em uma perspectiva sociodidática segundo a qual os fenômenos didáticos são e devem estar em continuidade direta com os fenômenos linguísticos, o presente texto parte de uma análise da pluralidade sociolinguística para, em seguida, obter dela uma conceitualização do que é uma competência linguística necessariamente sociolinguística. Ele confronta essas práticas sociolinguísticas heterogêneas e essas competências de utilização da pluralidade linguística no processo de elaboração e de ensino de línguas sem socialização e homogeneizadas sob a forma padrão artificialmente construído para fins políticos ideológicos. O artigo também analisa a divulgação e imposição consentida dessas línguas em termos de hegemonia e mostra em que isso produz discriminações negativas condenáveis por razões éticas e jurídicas, assim como fracassos socioeducativos. Ele propõe, por fim, princípios didáticos e orientações concretas de intervenção para integrar progressivamente e em profundidade a pluralidade linguística e cultural no ensino de línguas e em uma educação humanista pelas línguas. PALAVRAS-CHAVE: Discriminação linguística. Educação linguística. Ideologia. didática

Critical mass for a Patlak-Keller-Segel model with degenerate diffusion in higher dimensions

This paper is devoted to the analysis of non-negative solutions for a generalisation of the classical parabolic-elliptic Patlak-Keller-Segel system with $d\ge3$ and porous medium-like non-linear diffusion. Here, the non-linear diffusion is chosen in such a way that its scaling and the one of the Poisson term coincide. We exhibit that the qualitative behaviour of solutions is decided by the initial mass of the system. Actually, there is a sharp critical mass $M_c$ such that if $M \in (0,M_c]$ solutions exist globally in time, whereas there are blowing-up solutions otherwise. We also show the existence of self-similar solutions for $M \in (0,M_c)$. While characterising the eventual infinite time blowing-up profile for $M=M_c$, we observe that the long time asymptotics are much more complicated than in the classical Patlak-Keller-Segel system in dimension two

Lightweight and slender timber-concrete composite floors made of CLT-HPC and CLT-UHPC with ductile notch connectors

Cross-Laminated Timber (CLT) structures have been emerging worldwide for residential floors in multi-storey buildings thanks to their lightness, fast construction and low ecological footprint. This work aims at fostering this application, which is often limited by vibrational and deflection limits, by investigating composite slab floors made of CLT and High-Performance Concrete (HPC) slab as well as CLT and Ultra High-Performance Fiber Reinforced Concrete (UHPFRC). Firstly, the composite floors CLT-HPC and CLT-UHPFRC with a span of 8 m were designed by considering a multicriteria analysis. To assure a certain structural ductility, previously developed ductile notch connectors were employed. As an economic choice, no shear reinforcement in the concrete slab was employed. Then, fullscale composite beams were fabricated in order to verify the predicted flexural behaviour and natural frequency. A numerical analysis was carried out to verify the connectors could effectively yield before the timber collapse. The comparison between the numerical simulation and the slip measurements confirmed that about 50% of the notch connections fully yielded and underwent inelastic deformation which favors the structural ductility. In the case of the CLT-HPC floor, a reduction of the notch contact surface due to the use of plastic sheet waterproofing as well as shear cracks developing in the concrete close to the notch corner both reduced the expected structural stiffness. Finally, the CLT-UHPFRC floor is endowed with outstanding values of slenderness ratio (~35) and lightness (~2 kPa), while eliminating the use of shear reinforcement and sheet waterproofing