Self-Organized Criticality and Thermodynamic formalism

We introduce a dissipative version of the Zhang's model of Self-Organized Criticality, where a parameter allows to tune the local energy dissipation. We analyze the main dynamical features of the model and relate in particular the Lyapunov spectrum with the transport properties in the stationary regime. We develop a thermodynamic formalism where we define formal Gibbs measure, partition function and pressure characterizing the avalanche distributions. We discuss the infinite size limit in this setting. We show in particular that a Lee-Yang phenomenon occurs in this model, for the only conservative case. This suggests new connexions to classical critical phenomena.Comment: 35 pages, 15 Figures, submitte

Interface tactile pour la saisie guidée de connaissances

International audienceIn recent years, artificial intelligence tools have democratized and are increasingly used by people who are not experts in the field. These artificial intelligence tools, like rule-based or constraint-based systems require the input of human expertise to replicate the desired reasoning. Despite the explosion of new devices and new input paradigms, such as tablets and other touch interfaces, it seems that the usability of these tools have not taken advantage of these recent advances. In this article, we illustrate our concept with the rule edition in a fuzzy expert system. The special feature of fuzzy logic is that these rules look closer to natural language than classical logic. We present our work that involves the use of new touch interfaces to edit a fuzzy rule base with one finger. We end this section by the evaluation of the interface with a user panel.Au cours de ces dernières années, les outils d'intelligence artificielle se sont démocratisés et sont de plus en plus sou-vent utilisés par des personnes qui ne sont pas expertes du domaine. Parmi ces outils d'intelligence artificielle, les systèmes à base de règles ou de contraintes nécessitent la saisie de l'expertise humaine afin de reproduire le comporte-ment souhaité. Malgré l'explosion des nouveaux périphé-riques et de nouveaux paradigmes de saisie, comme les tablettes et autres interfaces tactiles, l'ergonomie de ces outils semble ne pas avoir profité de toutes ces avancées récentes. Dans cet article, nous prenons l'exemple d'un système expert flou pour lequel il faut rédiger des règles. La particu-larité de la logique floue est que ces règles sont construites d'une manière plus proche du langage naturel qu'en lo-gique classique. Nous présentons notre travail qui consiste en l'exploitation des nouvelles interfaces tactiles afin de rédiger une base de règles floues avec un seul doigt. Nous terminons cet article par l'évaluation de l'interface auprès d'un panel d'utilisateurs

Biliary cirrhosis and sepsis are two risk factors of failure after surgical repair of major bile duct injury post-laparoscopic cholecystectomy.

International audienceBACKGROUND: Major bile duct injury (MBDI) remains frequent after laparoscopic cholecystectomy (LC) reaching 0.3 to 0.6 % and is associated with a significant mortality rate. The aim of this study was to retrospectively analyze the factors likely to influence the long-term results of surgical repair for MBDI occurring after LC. METHODS: Medical records of patients referred to our referral center from January 1992 to January 2010 for management of bile duct injury following LC were retrospectively analyzed, and patients with MBDI were identified. Clinicopathological factors likely to influence long-term results after surgical repair were assessed by univariate and multivariable analysis. RESULTS: During the study period, 38 patients were treated for MBDI. These 38 patients underwent Roux-en-Y hepaticojejunostomy (HJ) or HJ revision in 25 (66 %) and 13 (34 %) cases, respectively. The median follow-up period was 93 (26-204) months. A Clavien-Dindo post-operative morbidity class >3 occurred in 10 (26 %) cases and was independently associated with a surgical repair performed during a sepsis period (OR = 102.5; IC 95 % [7.12; 11,352], p < 0.007). Long-term results showed that biliary strictures occurred in 5 (13 %) cases and were associated with sepsis (p < 0.006), liver cirrhosis (p < 0.002) and post-operative complications (p < 0.012). Multivariate analysis revealed that only liver cirrhosis remained predictive of stricture (OR = 26.4, 95 % CI [2; 1,018], p < 0.026). CONCLUSION: When MBDI occurs following LC, HJ seems to be the optimal treatment but should not be performed during a sepsis period. Long-term results are significantly altered by the presence of a biliary cirrhosis at time of repair

Quantum Coherence at Low Temperatures in Mesoscopic Systems: Effect of Disorder

We study the disorder dependence of the phase coherence time of quasi one-dimensional wires and two-dimensional (2D) Hall bars fabricated from a high mobility GaAs/AlGaAs heterostructure. Using an original ion implantation technique, we can tune the intrinsic disorder felt by the 2D electron gas and continuously vary the system from the semi-ballistic regime to the localized one. In the diffusive regime, the phase coherence time follows a power law as a function of diffusion coefficient as expected in the Fermi liquid theory, without any sign of low temperature saturation. Surprisingly, in the semi-ballistic regime, it becomes independent of the diffusion coefficient. In the strongly localized regime we find a diverging phase coherence time with decreasing temperature, however, with a smaller exponent compared to the weakly localized regime.Comment: 21 pages, 30 figure

Effects of finite curvature on soliton dynamics in a chain of nonlinear oscillators

We consider a curved chain of nonlinear oscillators and show that the interplay of curvature and nonlinearity leads to a number of qualitative effects. In particular, the energy of nonlinear localized excitations centered on the bending decreases when curvature increases, i.e. bending manifests itself as a trap for excitations. Moreover, the potential of this trap is double-well, thus leading to a symmetry breaking phenomenon: a symmetric stationary state may become unstable and transform into an energetically favorable asymmetric stationary state. The essentials of symmetry breaking are examined analytically for a simplified model. We also demonstrate a threshold character of the scattering process, i.e. transmission, trapping, or reflection of the moving nonlinear excitation passing through the bending.Comment: 13 pages (LaTeX) with 10 figures (EPS

Impact of the European Clinical Trials Directive on prospective academic clinical trials associated with BMT

The European Clinical Trials Directive (EU 2001; 2001/20/EC) was introduced to improve the efficiency of commercial and academic clinical trials. Concerns have been raised by interested organizations and institutions regarding the potential for negative impact of the Directive on non-commercial European clinical research. Interested researchers within the European Group for Blood and Marrow Transplantation (EBMT) were surveyed to determine whether researcher experiences confirmed this view. Following a pilot study, an internet-based questionnaire was distributed to individuals in key research positions in the European haemopoietic SCT community. Seventy-one usable questionnaires were returned from participants in different EU member states. The results indicate that the perceived impact of the European Clinical Trials Directive has been negative, at least in the research areas of interest to the EBMT

Stay or drift? Queen acceptance in the ant Formica paralugubris

Abstract.: The acceptance of new queens in ant colonies has profound effects on colony kin structure and inclusive fitness of workers. Therefore, it is important to study the recognition and discrimination behaviour of workers towards reproductive individuals entering established colonies. We examined the acceptance rate of queens in populations of the highly polygynous ant F. paralugubris, where the genetic differentiation among nests and discrimination ability among workers suggest that workers might reject foreign queens. We experimentally introduced young queens in their natal nest and in foreign nests. Surprisingly, the survival rate of mated queens did not differ significantly when introduced in a foreign male-producing nest, a foreign female-producing nest, or the natal nest. Moreover, the survival of virgin queens in their natal nest was twice the one of mated queens, suggesting that mating status plays an important role for acceptance. The results indicate that other factors than queen discrimination by workers are implicated in the limited longdistance gene flow between nests in these population

The smectitic minerals in a bentonite deposit from melo (Uruguay)

International audienceA nearly monomineralic 1.5 m thick bentonite bed sampled in Melo (Uruguay) appears to be a pure high-charge montmorillonite: [Si3.94 Al0.06] (Al1.40 Fe 3+ 0.11 Ti0.02 Mg0.49 Mn0.01) O10 (OH)2 Na0.01 K0.08 Ca0.18. However, contrasting swelling behaviors have been evidenced by fitting the experimental X-ray diffraction patterns recorded on oriented preparations of the same sample in different saturation states. According to the expandability of the layers in the Ca-, K- and K-Ca-saturated (that is saturated first with K + and subsequently with Ca2+) states, three "layer types" were defined. Low-, intermediate-, and high-charge layers are fully, partly, and not expandable, respectively, after K-saturation. Collapse of high-charge layers is not reversible after subsequent Ca-saturation, most likely because of tetrahedral substitutions. These three different layer types are segregated in two distinct randomly interstratified mixedlayer phases. TSA and CEC are shown to depend on the interlayer cation composition