Calcul de k plus courts chemins dans de grands graphes multimodaux et dépendant du temps.

International audienceL'objectif est d'établir une méthode de calcul de k plus courts chemins contraints par un langage régulier partant à un horaire donné dans de grands multigraphes multimodaux dépendant du temps et respectant la condition FIFO. Soient n et m le nombre de noeuds et d'arcs du graphe; un chemin est une séquence d'arcs adjacents deux à deux.Bien que pour le cas classique du calcul de k plus courts chemins non contraints sur des graphes monomodaux statiques, des méthodes de résolution (Eppstein 94 et améliorations) très efficaces (O(m + n*log(n) + k) en temps) existent, ces approches sont difficilement utilisables dans notre cas car elles se basent sur un précalcul en parcours arrière.Nous proposons un algorithme à fixation d'étiquettes pour le calcul des k plus courts chemins multimodaux dépendant du temps. La difficulté de la résolution vient de ce qu'aucune règle de dominance ne peut s'appliquer, rendant tout parcours en largeur naïf prohibitif. Nous introduisons donc une régle de sélection du pivot prenant en compte les solutions ainsi que l'exploration des itérations précédantes. Ainsi, le graphe des k plus courts chemins générés par l'exploration s'étend le plus possible non pas vers les branches de coûts provisoires minimaux mais vers les branches de coûts définitifs minimaux, et parmis elles, celles dont les coûts provisoires sont minimaux. La technique est donc, dans l'esprit, très proche de l'algorithme A*. La complexité temporelle estimée est de O(n*m+k*n*log(n)) avec une complexité spatiale de O(k*n).De plus, toutes les techniques d'accélération classiques n'utilisant pas d'évaluation arrière optimale (A*, landmarks) deviennent directement utilisables ce qui permet d'accroître les performances d'éxécution.En conclusion, la résolution du problème des k plus courts chemins multimodaux dépendants du temps par l'extension des méthodes de résolution vastement étudiées du problème des k plus courts chemins conduisent à de très mauvaises performances temporelles.Nous proposons des algorithmes permettant de meilleures performances expérimentales.</p

A k-shortest paths based algorithm for multimodal time-dependent networks to compute alternative routes

Rapport LAAS n° 15273Usual computations of alternative routes and the measure of their similarities and/or dierences do not embrace the variability of networks specics and user preferences. Indeed, the denition and evaluation of the dierence between paths is often embedded into algorithm internals and thus does not take into account that similar or dissimilar paths may vary depending on the user and/or the network. In this article, a generic method to generate alternative routes on FIFO time-dependent multimodal graphs with regular language constraints is presented. It relies on the computation, in a rst stage, of the k-shortest paths before the enforcement of a distinction criteria based on word metrics and comparison procedures in a second stage. We rst present a variant of a k-shortest paths algorithm taking into account both the multimodality and the time-dependency inherent to transportation networks. Then, we propose several methods for evaluating the dierences between routes. Experiments are conducted in realistic cases of transportation networks and associated results show the relative eciency and interest of the approach

Adaptations of k-Shortest Path Algorithms for Transportation Networks

International audienceThe computation of the k-shortest paths, should they be elementary or not, has been extensively investigated in the literature, yielding to extremely performant algorithms. For elementary paths, the best known algorithm to this day is the algorithm of Yen enhanced by the extension of Lawler,while for the search of non-elementary paths, the algorithm with the best complexity is due to Eppstein but is outperformed in practice by the Recursive Enumeration Algorithm. In the context of transportation networks, graphs are time dependent, meaning that the cost of an edge depends on the time at which it is crossed. If for each edge one cannot arrive later if he departs earlier, the network is said to respect the FIFO property. Underthis hypothesis, the usual Dijkstra shortest path algorithm is still polynomial. Additionally, since each edge is associated to a transportation type, one may want to restrict a path to be in a regular language. To find a shortest path under this constraint a polynomial algorithm, called DRegLC, works on the product of the network and the graph representing an automaton accepting the regular language.In this paper, some k-shortest paths algorithms are adapted to be used on such transportation networks with a regular language constraint. Also, the computation of the k-shortest elementary paths is considered using k-shortest non elementary paths algorithms, deleting loops while searching if possible. To address this approach, a new algorithm is presented to speedup the search of elementary paths while scanning as few paths containing loops as possible

Rare agressive form of giant-cell granuloma: a three years follow-up case report and discussion about medical therapeutic solutions

Introduction: Central giant cell granuloma (CGCG) is a rare and benign intraosseous lesion that usually occurs in the mandible and the maxilla. It might be aggressive. Nowadays, several treatments exist. Observation: This case report, with a three years follow-up, was about an aggressive and recurring form of CGCG exclusively managed by surgical approach. Comments: Several pharmacologic approaches are possible (intralesional injections of glucocorticoids, administration of calcitonin, alpha-2a interferon, denosumab) and could be an interesting alternative or complement to the surgical management when CGCG is aggressive, recurring, or non resectable. Conclusion: Surgical approach is the gold standard for the treatment of CGCG but sometimes, pharmacologic approaches could be proposed. According to the scientific literature, denosumab appears as a reliable and effective treatment but more prospective studies are needed

A Bayesian Approach to Morphological Models Characterization

International audienceMorphological models are commonly used to describe microstructures observed in heterogeneous materials. Usually, these models depend upon a set of parameters that must be chosen carefully to match experimental observations conducted on the microstructure. A common approach to perform the parameters determination is to try to minimize an objective function, usually taken to be the discrepancy between measurements computed on the simulations and on the experimental observations, respectively. In this article, we present a Bayesian approach for determining the parameters of morphological models, based upon the definition of a posterior distribution for the parameters. A Monte Carlo Markov Chains (MCMC) algorithm is then used to generate samples from the posterior distribution and to identify a set of optimal parameters. We show on several examples that the Bayesian approach allows us to properly identify the optimal parameters of distinct morphological models and to identify potential correlations between the parameters of the models

Personality disorders, but not cancer severity or treatment type, are risk factors for later generalised anxiety disorder and major depressive disorder in non metastatic breast cancer patients

International audienceThis study aimed to determine whether personality disorders were associated with later Major Depressive Disorder (MDD) or Generalised Anxiety Disorder (GAD) in breast cancer patients. This longitudinal and multicentric study included 120 French non-metastatic breast cancer patients. After cancer diagnosis (T1) and 7 months after diagnosis (T3), we assessed MDD and GAD (Mini International Neuropsychiatric Interview 5.0). We assessed personality disorders 3 months after diagnosis (VKP). We used multiple logistic regression analysis to determine what were the factors associated with GAD and MDD at T3. At T3, prevalence rate was 10.8% for MDD and 19.2% for GAD. GAD at T3 was significantly and independently associated with GAD at T1 and with existence of a personality disorder, no matter the cluster type. MDD at T3 was significantly and independently associated with MDD at T1 and with the existence of a cluster C personality disorder. Initial cancer severity and the type of treatment used were not associated with GAD or MDD at T3. Breast cancer patients with personality disorders are at higher risk for GAD and MDD at the end of treatment. Patients with GAD should be screened for personality disorders. Specific interventions for patients with personality disorders could prevent psychiatric disorders

Reference values of aerobic fitness in the contemporary paediatric population

International audienceAims There has been a growing interest in the use of markers of aerobic physical fitness (VO2max assessed by cardiopulmonary exercise testing (CPET)) in the follow-up of paediatric chronic diseases. The dissemination of CPET in paediatrics requires valid paediatric VO2max reference values to define the upper and lower normal limits. This study aimed to establish VO2max reference Z-scores values, from a large cohort of children representative of the contemporary paediatric population, including those with extreme weights. Methods and results In this cross-sectional study, 909 children aged 5 to 18-years-old from the general French population (development cohort), and 232 children from the general German and US populations (validation cohort) underwent a CPET, following the guidelines on high-quality CPET assessment. Linear, quadratic, and polynomial mathematical regression equations were applied to identify the best VO2max Z-score model. Predicted and observed VO2max values using the VO2maxZ-score model, and the existing linear equations were compared, in both development and validation cohorts. For both sexes, the mathematical model using natural logarithms of VO2max, height, and BMI was the best fit for the data. This Z-score model could be applied to normal and extreme weights and was more reliable than the existing linear equations, in both internal and external validity analyses (https://play.google.com/store/apps/details?id=com.d2l.zscore). Conclusion This study established reference Z-score values for paediatric cycloergometer VO2max using a logarithmic function of VO2max, height and BMI, applicable to normal and extreme weights. Providing Z-scores to assess aerobic fitness in the paediatric population should be useful in the follow-up of children with chronic diseases

Relationship between extracellular low-molecular-weight thiols and mercury species in natural lake periphytic biofilms

The uptake of mercury by microorganisms is a key step in the production of methylmercury, a biomagnifiable toxin. Mercury complexation by low molecular weight (LMW) thiols can affect its bioavailability and thus the production of methylmercury. Freshwater biofilms were sampled in the summer using artificial Teflon substrates submerged for over a year to allow natural community colonization in the littoral zone of a Boreal Shield lake. Inside biofilms, concentrations of different extracellular thiol species (thioglycolic acid, L-cysteine-L-glycine, cysteine, and glutathione) were up to three orders of magnitude greater than in the surrounding water column, potentially more readily controlling mercury speciation than in water column. All biofilm thiols except thioglycolic acid were highly correlated to chlorophyll a, likely indicating an algal origin. Extracellular total mercury represented 3 ± 1% of all biofilm mercury and was preferentially found in the capsular fraction. Levels of LMW thiols of presumed algal origins were highly correlated with total mercury in the mobile colloidal fraction of biofilms. We propose that periphytic phototrophic microorganisms such as algae likely affect the bioavailability of mercury through the exudation of LMW thiols, and thus they may play a key role in the production of methylmercury in biofilms