General Algorithm For Improved Lattice Actions on Parallel Computing Architectures

Quantum field theories underlie all of our understanding of the fundamental forces of nature. The are relatively few first principles approaches to the study of quantum field theories [such as quantum chromodynamics (QCD) relevant to the strong interaction] away from the perturbative (i.e., weak-coupling) regime. Currently the most common method is the use of Monte Carlo methods on a hypercubic space-time lattice. These methods consume enormous computing power for large lattices and it is essential that increasingly efficient algorithms be developed to perform standard tasks in these lattice calculations. Here we present a general algorithm for QCD that allows one to put any planar improved gluonic lattice action onto a parallel computing architecture. High performance masks for specific actions (including non-planar actions) are also presented. These algorithms have been successfully employed by us in a variety of lattice QCD calculations using improved lattice actions on a 128 node Thinking Machines CM-5. {\underline{Keywords}}: quantum field theory; quantum chromodynamics; improved actions; parallel computing algorithms

Architecture des milieux

Cities do not wait on architecture to evolve - neither forethought nor attention are necessary for them to show extraordinary growth and energy. But contemporary political discussion directly addresses our living conditions and environment: how can we answer new social and ecological problems without renewing our thoughts on architecture and urban planning, or examining associated practices?Die Stadt im Werden erinnert uns täglich an die Tatsache: ausdehnen und verwandeln kann sich eine Stadt ganz gut ohne Architektur! Die aktuelle politische Debatte befragt jedoch ganz direkt unser Lebensumfeld. Ohne völliges Umdenken was Urbanismus und Architektur anbelangt geht es nicht. Die Architektur der Milieus bringt eine Hypothese um diese Kollektivarbeit zu nähren: zugleich reparieren und neu fundieren

Thermo-mechanical analysis of GaAs devices under temperature-humidity-bias testing

International audienceAccelerated life tests on microelectronic devices are needed to estimate their degradation under severe environment. THB (Temperature Humidity Bias) [1] at 85°C and 85%RH (relative humidity) is commonly used for reliability studies. Empirical acceleration laws, used for THB test take into account the temperature change (from 22°C to 85°C), but they do not quantify its impact of the corresponding thermo-elastic stress which it adds to the residual stress in the die and of possible microstructure changes. The aim of this work is to determine the thermo-mechanical stresses induced in the active layer of a Gallium Arsenide (GaAs) chip by the THB test. They are due to the mismatch in Coefficients of Thermal Expansion (CTE) between the stack of thin film materials used as metallurgic interconnection and the intermediate dielectric layers above the active area of the chip. To estimate this stress, fist layers thicknesses measurement have been made with various techniques; second few configurations have been used to simulate heating and finally " complete " 2D Finite Element Analysis (FEA) has been performed. Elastic and thermo-physical materials data come from the literature. The results indicate compression of metal gate (Ti/Al/Au) and tensile stress concentration in the SiNx passivation layer. The outcomes is compared with THB test results from [2] and suggests that stress induced by heating must be considered to explain failure during THB test

The space of cultural practices: from the construction of social space to the study of subgroups through specific class analysis.

Quels sont les déterminants sociaux des orientations culturelles et, en particulier, quel est l’effet de la position de classe sur les différences observées dans l’univers des pratiques culturelles? Le présent article revisite cette question désormais classique de sociologie de la culture et de sociologie de la stratification, à partir de données d’une enquête par questionnaire menée en France en 2003 (“Participation culturelle et sportive”). En mobilisant une démarche systémati-que d’analyse géométrique des données, il s’agit ici de discuter empiriquement l’importance de l’effet de l’appartenance de classe, telle qu’elle peut être saisie à partir de nomenclatures socio--professionnelles à différents niveaux d’agrégation. Une fois déterminé l’effet de l’appartenance de classe et évalué son importance selon divers critères, on étudie dans un second temps les variations sociales à l’intérieur de trois groupes sociaux particuliers, afin de montrer que l’on peut interpréter sociologiquement la diversité de pratiques culturelles au sein de différentes catégories sociales, voire à des niveaux encore plus fins.What are the social determinants of cultural orientations and, in particular, what is the effect of class position on the differences observed in the universe of cultural practices? This article revisits this classic question of the sociology of culture and the sociology of stratification, based on the data of a survey conducted in France in 2003 ("Cultural and sports participation"). Mobilizing a systematic approach based on geometric data analysis, the aim of this article is to discuss empirically the importance of class belonging effect, as it can be understood from socio-professional nomenclatures at different levels of aggregation. Once the effect of class belonging has been determined and its importance according to various criteriaassessed, the social variations within three social groups are examined, in order to show that it is possible to interpret sociologically the diversity of cultural practices within different social categories, possibly even in more refined levels.Quais são as determinantes sociais das orientações culturais e, em particular, qual é o efeito da po-sição de classe sobre as diferenças observadas no universo das práticas culturais? O presente artigo revisita essa questão doravante clássica da sociologia da cultura e da sociologia da estratificação, a partir dos dados de uma pesquisa por questionário, realizada na França em 2003 (“Participação cultural e esportiva”). Mobilizando uma abordagem sistemática de análise geométrica dos dados, trata-se aqui de discutir empiricamente a importância do efeito de pertencimento de classe, tal como pode ser apreendida a partir de nomenclaturas socioprofissionais em diferentes níveis de agregação. Uma vez determinado o efeito do pertencimento de classe e avaliada sua importância de acordo com diversos critérios, estudaremos, em seguida, as variações sociais no interior de três grupos sociais em particular, a fim de mostrar que é possível interpretar sociologicamente a diversidade de práticas culturais no seio de diferentes categorias sociais, eventualmente em níveis ainda mais finos

Approches par maillage conforme en mécanique non-linéaire de la rupture : méthode G-theta et modèle de zone cohésive

National audienceOn présente deux approches pour la fissuration en élastoplasticité : l'une basée sur l'introduction d'une grandeur énergétique caractéristique de la fissuration pertinente dans ce contexte, l'autre associant remaillage adaptatif et prédiction de trajet de fissuration pour un modèle cohésif. Ces approches, mises en œuvre dans le code aux éléments finis Zset/Zebulon, sont évaluées sur des problèmes représentatifs simples.See http://hal.archives-ouvertes.fr/docs/00/59/29/29/ANNEX/r_905JKSQE.pd

Development of compositional-gradient metallic alloys for combinatorial investigation of microstructures

International audienc

Infrared Behavior of the Gluon Propagator on a Large Volume Lattice

The first calculation of the gluon propagator using an order a^2 improved action with the corresponding order a^2 improved Landau gauge fixing condition is presented. The gluon propagator obtained from the improved action and improved Landau gauge condition is compared with earlier unimproved results on similar physical lattice volumes of 3.2^3 \times 6.4 fm^4. We find agreement between the improved propagator calculated on a coarse lattice with lattice spacing a = 0.35 fm and the unimproved propagator calculated on a fine lattice with spacing a = 0.10 fm. This motivates us to calculate the gluon propagator on a coarse large-volume lattice 5.6^3 \times 11.2 fm^4. The infrared behavior of previous studies is confirmed in this work. The gluon propagator is enhanced at intermediate momenta and suppressed at infrared momenta. Therefore the observed infrared suppression of the Landau gauge gluon propagator is not a finite volume effect.Comment: 8 pages, 4 figures, minor typos corrected and repsonse to referees comment

Use of space-resolved in-situ high energy X-ray diffraction for the characterization of the compositional dependence of the austenite-to-ferrite transformation kinetics in steels

In-situ high energy X-Ray diffraction (HEXRD) was used on compositionally graded steels to study the effect of substitutional elements on ferrite growth kinetics in Fe-C-X and Fe-C-X-Y systems. Two systems have been selected to illustrate the applicability of the combinatorial approach in studying such transformations, Fe-C-Mn and Fe-C-Mn-Mo. Comparison between the measured ferrite growth kinetics using HEXRD and the predicted ones using Para-Equilibrium (PE) and Local Equilibrium with Negligible Partitioning (LENP) models indicates that the fractions reached at the stasis of transformation are lower than the predicted ones. Experiments indicated a deviation of measured kinetics from both PE and LENP models when increasing Mn and decreasing Mo (in Fe-C-Mn-Mo system). The large amount of data that can be obtained using this approach can be used for validating existing models describing ferrite growth kinetics

Scaling behavior of the overlap quark propagator in Landau gauge

The properties of the momentum space quark propagator in Landau gauge are examined for the overlap quark action in quenched lattice QCD. Numerical calculations are done on three lattices with different lattice spacings and similar physical volumes to explore the approach of the quark propagator toward the continuum limit. We have calculated the nonperturbative momentum-dependent wave function renormalization function Z(p) and the nonperturbative mass function M(p) for a variety of bare quark masses and perform an extrapolation to the chiral limit. We find the behavior of Z(p) and M(p) are in reasonable agreement between the two finer lattices in the chiral limit, however the data suggest that an even finer lattice is desirable. The large momentum behavior is examined to determine the quark condensate.Comment: 9 pages, 5 figures, Revtex 4. Streamlined presentation, additional data. Final versio

Inventaire de la faune apiforme (Hymenoptera, Apoidea) des quartiers Myosotis et Engeland à Uccle (Bruxelles, Belgique)

peer reviewedCe travail présente l’inventaire des abeilles sauvages (Hymenoptera Apoidea) observées dans l’ancien quartier Myosotis et le nouveau quartier Engeland de la commune d’Uccle à Bruxelles. Via une campagne d’échantillonnage dans les deux quartiers, 708 spécimens ont été capturés ou observés appartenant à 58 espèces différentes des 6 familles d’abeilles sauvages de Belgique. La faune apiforme capturée représente 14% de la faune belge et 28% de la faune bruxelloise. On y retrouve 10 espèces mono ou oligolectiques et 5 espèces font l’objet d’enjeux de conservation spécifiques selon la liste rouge des abeilles de Belgique. Quelques recommandations de gestion de conservation sont discutées dans ce travail en vue de favoriser au maximum la richesse de ces anthophiles pour la commune d’Uccle