1,077 research outputs found

    Scalable Parallel Numerical Constraint Solver Using Global Load Balancing

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    We present a scalable parallel solver for numerical constraint satisfaction problems (NCSPs). Our parallelization scheme consists of homogeneous worker solvers, each of which runs on an available core and communicates with others via the global load balancing (GLB) method. The parallel solver is implemented with X10 that provides an implementation of GLB as a library. In experiments, several NCSPs from the literature were solved and attained up to 516-fold speedup using 600 cores of the TSUBAME2.5 supercomputer.Comment: To be presented at X10'15 Worksho

    Certainty Closure: Reliable Constraint Reasoning with Incomplete or Erroneous Data

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    Constraint Programming (CP) has proved an effective paradigm to model and solve difficult combinatorial satisfaction and optimisation problems from disparate domains. Many such problems arising from the commercial world are permeated by data uncertainty. Existing CP approaches that accommodate uncertainty are less suited to uncertainty arising due to incomplete and erroneous data, because they do not build reliable models and solutions guaranteed to address the user's genuine problem as she perceives it. Other fields such as reliable computation offer combinations of models and associated methods to handle these types of uncertain data, but lack an expressive framework characterising the resolution methodology independently of the model. We present a unifying framework that extends the CP formalism in both model and solutions, to tackle ill-defined combinatorial problems with incomplete or erroneous data. The certainty closure framework brings together modelling and solving methodologies from different fields into the CP paradigm to provide reliable and efficient approches for uncertain constraint problems. We demonstrate the applicability of the framework on a case study in network diagnosis. We define resolution forms that give generic templates, and their associated operational semantics, to derive practical solution methods for reliable solutions.Comment: Revised versio

    POS0724 GENDER DIFFERENCES IN THROMBOTIC PRIMARY ANTIPHOSPHOLIPID SYNDROME IN A LARGE COHORT OF PATIENTS FROM FOUR EUROPEAN CENTERS

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    Background:Autoimmune diseases occur more frequently in females and their course and severity can be affected by gender. Antiphospholipid syndrome (APS) is a systemic autoimmune disorder in which antiphospholipid antibodies (aPL) exert a pathogenic role resulting in vascular thrombosis and/or pregnancy morbidities. Data about gender differences in thrombotic APS (t-APS) are still scarce1,2.Objectives:To evaluate the differences in frequency, disease expression and severity between females and males affected by primary t-APS.Methods:Retrospective study enrolling subjects with a formal diagnosis of primary APS (Miyakis 2006) with vascular thrombosis at onset. Women who presented with obstetric events as first aPL-related manifestation were excluded. All the patients were followed from 1967 to 2019 in four European centers: three French centers and one Italian center.Results:The study included 433 patients (68% females, 32% males). Median age at t-APS onset [31 (24-46) vs 41 (29-53) years, p<0.001] and at diagnosis [34 (27-50) vs 46 (34-57) years, p<0.001] was significantly lower in females.The most common presenting manifestations were venous thrombosis (60%) followed by arterial events (37%) and catastrophic APS (3%). Venous events were more frequent in women as compared to men (64% vs 51% p:0.012 OR:1.7 [1.1-2.5]). Sites of venous thrombosis included: limbs (35%), pulmonary (17%), cerebral (3%), portal and inferior cava (2%) and retinal (1%) veins, without gender differences. The arterial events were more frequent among men (43% vs 34% p:0.053). Strokes (27%) and myocardial infarctions (4%) were the most frequent manifestations, followed by thrombosis of limbs (2%), retina (2%) and abdominal organs (1%). Noteworthy, only men presented with visceral ischemia.During the follow-up, new thrombosis occurred in 41% of patients (179/433). 33% out of them had at least two episodes and these occurred especially among males (22% vs 10% p:0.001 OR:2.5 [1.3-4.8]). New events were mostly of the same type, but â…“ of patients presented a switch from venous to arterial side and viceversa, with no gender differences.Complete aPL profile was available in 357 subjects: 33% had single aPL positivity, 24% double positivity and 43% triple positivity, with no differences between women and men. About 80% of the patients had a concomitant risk factor (RF) for thrombosis. Established cardiovascular RFs were more represented among men as shown in table 1. In women, estrogenic exposure was the main RFs, present in almost 40% of them.Table 1.MALESn= 137FEMALESn= 296POR [IC 95%]Traditional cardiovascular RFs, n (%)Smoke66 (48)81 (27)<0.0012.5 [1.6-3.8]Arterial hypertension59 (43)75 (25)<0.0012.2 [1.5-3.4]Dyslipidemia52 (38)72 (24)0.0041.9 [1.2-2.9]Diabetes16 (12)15 (5)0.0142.5 [1.8-5.1]Obesity13 (10)38 (13)nsOther thrombophilic factors, n (%)Estrogenic stimuli*0116 (39)-Trauma / surgery / immobilization21 (15)32 (11)nsCongenital thrombophilia9/94 (10)33/204 (16)nsData were compared using contingency tables, p value was calculated with Chi-Squared or Fisher exact test. *= hormonal therapy, pregnancy, post-partumConclusion:This gender-oriented analysis of patients with primary t-APS showed that women had the first vascular event at a younger age and mostly on the venous side, while men presented mainly with arterial events, later in life and suffered from more recurrent events. No differences were observed in the distribution of the aPL profile. The different frequency of arterial and venous events in the two groups could be attributed mainly to the presence of additional RFs rather than to biological gender-specific issues. However, it should be underlined that some RFs, such as the use of estrogens or classic cardiovascular RFs, are exclusive or more represented in one gender rather than the other, making it difficult to assess the link of causality between gender and manifestations of t-APS.References:[1]JF de Carvalho. Rheumatol Int. 2011.[2]LJ Jara. Lupus. 2005.Disclosure of Interests:None declare

    Renormalization of Crumpled Manifolds

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    We consider a model of D-dimensional tethered manifold interacting by excluded volume in R^d with a single point. By use of intrinsic distance geometry, we first provide a rigorous definition of the analytic continuation of its perturbative expansion for arbitrary D, 0 < D < 2. We then construct explicitly a renormalization operation, ensuring renormalizability to all orders. This is the first example of mathematical construction and renormalization for an interacting extended object with continuous internal dimension, encompassing field theory.Comment: 10 pages (1 figure, included), harvmac, SPhT/92-15

    Nouvelle approche de modélisation de milieux poreux. Application à l'os trabéculaire

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    Dans de nombreux domaines tels que la science des matériaux ou l'imagerie médicale, il est intéressant d'évaluer les propriétés mécaniques d'une structure. Pour ce faire, l'analyse par éléments finis est souvent utilisée. Cependant, son application à des milieux poreux complexes est limitée, car le nombre d'éléments nécessaires pour représenter la structure interne est très grand. Dans cette communication, nous proposons une nouvelle approche par éléments finis qui prend en compte la topologie de la structure étudiée. Pour cela, nous implémentons et améliorons une technique récente basée sur le squelette 3D, permettant de caractériser des milieux poreux complexes. Chaque travée de la structure interne peut alors être représentée par une chaîne de poutres rectilignes auxquelles sont attribuées les propriétés de l'arche. Cette approche permet de réduire considérablement le temps de calcul nécessaire à la simulation mécanique par éléments finis tout en présentant une bonne adéquation avec une technique de référence. Nous avons évalué cette technique sur des vecteurs de test, puis appliqué notre méthode sur des échantillons d'os trabéculaire afin d'en quantifier précisément l'élasticité. Ce nouveau procédé de modélisation donne de meilleurs résultats de rigidité par rapport aux techniques à éléments poutre existantes sur des vecteurs de test. Cette tendance se confirme également lors de son application à l'étude de la microarchitecture de l'os trabéculaire

    Analyse fractale par morceaux de radiographies osseuses

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    - L'objectif de cette étude est de proposer, à partir du mouvement brownien fractionnaire (fBm) de paramètre H, un modèle plus général qui puisse englober des phénomènes présentant un caractère fractal par morceaux lors d'une analyse en fréquence. Ce nouveau modèle est appelé pfBm de paramètres Ho en basse fréquence, Hi en haute fréquence, ces deux régimes étant séparés par une fréquence de coupure γ. Pour Ho=Hi=H, le pfBm se réduit au fBm, lui même étant le mouvement brownien pour H=0.5. Nous pensons que le pfBm fournit ainsi un outil plus flexible que le fBm pour l'expérimentateur. Nous avons montré que ce processus a des incréments stationnaires et qu'il est autosimilaire de paramètre Ho pour les basses fréquences et de paramètre Hi pour les hautes fréquences. Nous avons alors étudié des radiographies trabéculaires osseuses qui présentent ce caractère bifractal. Les résultats montrent que l'analyse fractale par morceaux est plus efficace que l'analyse fractale standard pour diagnostiquer les modifications de la micro-architecture osseuse liées à l'ostéoporose

    Caractérisation de milieux poreux par étude de leur géométrie 3D : Application à l'os trabéculaire

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    Cette communication présente le développement d'un ensemble d'outils permettant de caractériser un milieu poreux tel que l'os trabéculaire. Ce travail est basé sur une nouvelle technique permettant de localiser et d'individualiser les arches du milieu poreux. Nous nous intéressons principalement à la mesure d'anisotropie en 3 dimensions et au calcul d'indices d'orientation et de courbure pour chaque travée. Les différentes techniques mises en place sont comparées sur 2 populations différentes composées d'échantillons osseux ostéoporotiques et coxarthriques. Nous montrons que seuls les indices de courbure des travées permettent de discriminer de manière significative les 2 populations étudiées

    Surface critical behavior of driven diffusive systems with open boundaries

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    Using field theoretic renormalization group methods we study the critical behavior of a driven diffusive system near a boundary perpendicular to the driving force. The boundary acts as a particle reservoir which is necessary to maintain the critical particle density in the bulk. The scaling behavior of correlation and response functions is governed by a new exponent eta_1 which is related to the anomalous scaling dimension of the chemical potential of the boundary. The new exponent and a universal amplitude ratio for the density profile are calculated at first order in epsilon = 5-d. Some of our results are checked by computer simulations.Comment: 10 pages ReVTeX, 6 figures include
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