Remnants of compact binary mergers and next-generation numerical relativity codes

Numerical relativity (NR) simulations are crucial for studying the coalescence of compact binaries. Based on NR data, we produce a model for the mass and spin of the remnant black hole (BH) for the coalescence of black hole-neutron star systems, discussing its crucial role in gravitational wave (GW) modeling and in the parameter estimation of the two signals GW200105 and GW200115. In the context of binary neutron star merger simulations, we perform the first systematic study comparing results obtained with various neutrino treatments, the presence of turbulent viscosity and different grid resolutions. We find that the time of BH formation after merger is heavily affected by grid resolution and turbulent viscosity. An early BH formation limits matter ejection from the accretion disc, as the BH swallows a significant portion of it. Our results indicate that more reliable kilonova light curves are obtained only if the various ejecta components are present. Moreover, robust r-process nucleosynthesis yields require inclusion of both neutrino emission and reabsorption in simulations. Advanced neutrino schemes and turbulent viscosity in simulations resolved beyond current standards appear necessary for reliable astrophysical predictions. To carry out computationally demanding simulations of growing complexity, next-generation NR codes that can efficiently leverage the latest pre-exascale many-core and heterogeneous infrastructures are required. To this end we develop GR-Athena++, a new dynamical spacetime solver built on top of Athena++, that shows high-order convergence properties and excellent parallel scalability up to O(105) cores in full 3D binary black hole (BBH) merger simulations. Finally we present GR-AthenaK, the first performance-portable spacetime solver, obtained by refactoring GR-Athena++ with the Kokkos programming model. We demonstrate the correctness and convergence properties of GR-AthenaK with BBH runs on GPUs. GR-AthenaK shows a speedup ∼50 on one GPU compared to GR-Athena++ on a single CPU core

Gravitational-wave luminosity of binary neutron stars mergers

We study the gravitational-wave peak luminosity and radiated energy of quasicircular neutron star mergers using a large sample of numerical relativity simulations with different binary parameters and input physics. The peak luminosity for all the binaries can be described in terms of the mass ratio and of the leading-order post-Newtonian tidal parameter solely. The mergers resulting in a prompt collapse to black hole have largest peak luminosities. However, the largest amount of energy per unit mass is radiated by mergers that produce a hypermassive neutron star or a massive neutron star remnant. We quantify the gravitational-wave luminosity of binary neutron star merger events, and set upper limits on the radiated energy and the remnant angular momentum from these events. We find that there is an empirical universal relation connecting the total gravitational radiation and the angular momentum of the remnant. Our results constrain the final spin of the remnant black-hole and also indicate that stable neutron star remnant forms with super-Keplerian angular momentum.Comment: 5 pages, 4 figure

New-HOPLA--A Higher-Order Process Language with Name Generation

This paper introduces new-HOPLA, a concise but powerful language for higher-order nondeterministic processes with name generation. Its origins as a metalanguage for domain theory are sketched but for the most part the paper concentrates on its operational semantics. The language is typed, the type of a process describing the shape of the computation paths it can perform. Its transition semantics, bisimulation, congruence properties and expressive power are explored. Encodings are given of well-known process algebras, including pi-calculus, Higher-Order pi-calculus and Mobile Ambients

Benjamin F. Soares, (ed.), Muslim-Christian Encounters in Africa

Issu d’un colloque international organisé, sous le même titre, par l’Institute for the Study of Islamic Thought in Africa (ISITA) de la Northwestern University, en mai 2003, à Evanston (Illinois), cet ouvrage collectif, rassemblant, à une exception près, une sélection des communications présentées à cette occasion, se propose de combler un vide dans les études en sciences humaines et sociales centrées sur l’Afrique, en identifiant un domaine d’enquête de plus en plus stratégique qui risque d’..

Benjamin F. Soares, (ed.), Muslim-Christian Encounters in Africa

Issu d’un colloque international organisé, sous le même titre, par l’Institute for the Study of Islamic Thought in Africa (ISITA) de la Northwestern University, en mai 2003, à Evanston (Illinois), cet ouvrage collectif, rassemblant, à une exception près, une sélection des communications présentées à cette occasion, se propose de combler un vide dans les études en sciences humaines et sociales centrées sur l’Afrique, en identifiant un domaine d’enquête de plus en plus stratégique qui risque d’..

Benjamin F. Soares, Islam and the Prayer Economy. History and Authority in a Malian Town

Voilà un ouvrage qui, à cinq ans de sa parution, est désormais devenu une référence incontournable dans les deux domaines des études sur l’islam en Afrique et de l’anthropologie de l’islam. Y revenir aujourd’hui avec une recension certes tardive, c’est aussi essayer de rendre compte de cet impact si profond et, sans doute, destiné à durer. Au lieu d’en résumer la structure argumentative et les thèse principales, désormais bien connues des spécialistes, rappelons tout simplement qu’il s’agit d..

Écrire l’islam en bambara

Al-Hâjj Modibo Diarra, nouvel acteur du paysage religieux malien, publie régulièrement, depuis 1987, des ouvrages de vulgarisation islamique en langue bambara, comportant aussi des traductions de l’arabe (extraits coraniques inclus). Son initiative relie les langues, les formes de communication orales et écrites, les savoirs et les réseaux dans l’islam ouest-africain. Les librairies bamakoises les distribuent en même temps que le village de l’auteur demeure le centre de sa production. Le milieu des librairies urbaines sert de relais à un phénomène qui reste pourtant essentiellement rural, tant par ses origines que par sa destination. Le parcours biographique de l’auteur/traducteur est à cet égard emblématique. Cette production imprimée islamique en bambara reconfigure les pratiques et les savoirs islamiques.Al-Hajj Modibo Diarra, a new actor of the Malian religious landscape, since 1987 has been publishing several booklets popularizing Islamic doctrine in Bambara language. These also contain translations from Arabic (including excerpts from the Qur’an). This initiative ties relationships between languages, oral and written forms of communication, genres of knowledge, and networks in West African, especially Malian, Islam. The Islamic bookshops in Bamako serve as places of publication and circulation while the village where the writer lives is including the actual writing of these works. The milieu of urban Islamic bookshops proves to work as a link for a phenomenon which remains, though, fundamentally rural, both in its origins and in its target. However, this very phenomenon must also be understood as a result of the growing integration of a milieu so far considered impervious into different kinds of networks that go beyond a merely local setting: the author/translator’s biography considered here is a case in point. The impact of this Bambara Islamic literature is discussed, alongside its implications upon local representations and reconfigurations of Islamic knowledge.Al-Hajj Modibo Diarra, nuevo actor del paisaje religioso de Mali, publica regularmente, desde 1987, obras de vulgarización islámica en lengua bambara, incluso traducciones del árabe (extractos coránicos incluidos). Su iniciativa une los idiomas, las formas de comunicación orales y escritas, los saberes y las redes en el Islam del oeste africano. Las librerías bamaquesas las distribuyen mientras que el poblado del autor sigue siendo el centro de su producción. El ambiente de las librerías urbanas sirve de relevo a un fenómeno que permanece sin embargo esencialmente rural, tanto por sus orígenes como por su destinación. El recorrido biográfico del autor/ traductor es en este sentido emblemático. Esta producción impresa islámica en bambara reconfigura las prácticas y los saberes islámicos. (trad. Véronica Giménez Béliveau

On Julia\u27s Efficient Algorithm for Subtyping Union Types and Covariant Tuples (Artifact)

This is the artifact for the pearl paper "On Julia\u27s efficient algorithm for subtyping union types and covariant tuples.

Acute: high-level programming language design for distributed computation

Existing languages provide good support for typeful programming of standalone programs. In a distributed system, however, there may be interaction between multiple instances of many distinct programs, sharing some (but not necessarily all) of their module structure, and with some instances rebuilt with new versions of certain modules as time goes on. In this paper we discuss programming language support for such systems, focussing on their typing and naming issues. We describe an experimental language, Acute, which extends an ML core to support distributed development, deployment, and execution, allowing type-safe interaction between separately-built programs. The main features are: (1) type-safe marshalling of arbitrary values; (2) type names that are generated (freshly and by hashing) to ensure that type equality tests suffice to protect the invariants of abstract types, across the entire distributed system; (3) expression-level names generated to ensure that name equality tests suffice for type-safety of associated values, e.g. values carried on named channels; (4) controlled dynamic rebinding of marshalled values to local resources; and (5) thunkification of threads and mutexes to support computation mobility. These features are a large part of what is needed for typeful distributed programming. They are a relatively lightweight extension of ML, should be efficiently implementable, and are expressive enough to enable a wide variety of distributed infrastructure layers to be written as simple library code above the byte-string network and persistent store APIs. This disentangles the language runtime from communication intricacies. This paper highlights the main design choices in Acute. It is supported by a full language definition (of typing, compilation, and operational semantics), by a prototype implementation, and by example distribution libraries