The discriminative functional mixture model for a comparative analysis of bike sharing systems

Bike sharing systems (BSSs) have become a means of sustainable intermodal transport and are now proposed in many cities worldwide. Most BSSs also provide open access to their data, particularly to real-time status reports on their bike stations. The analysis of the mass of data generated by such systems is of particular interest to BSS providers to update system structures and policies. This work was motivated by interest in analyzing and comparing several European BSSs to identify common operating patterns in BSSs and to propose practical solutions to avoid potential issues. Our approach relies on the identification of common patterns between and within systems. To this end, a model-based clustering method, called FunFEM, for time series (or more generally functional data) is developed. It is based on a functional mixture model that allows the clustering of the data in a discriminative functional subspace. This model presents the advantage in this context to be parsimonious and to allow the visualization of the clustered systems. Numerical experiments confirm the good behavior of FunFEM, particularly compared to state-of-the-art methods. The application of FunFEM to BSS data from JCDecaux and the Transport for London Initiative allows us to identify 10 general patterns, including pathological ones, and to propose practical improvement strategies based on the system comparison. The visualization of the clustered data within the discriminative subspace turns out to be particularly informative regarding the system efficiency. The proposed methodology is implemented in a package for the R software, named funFEM, which is available on the CRAN. The package also provides a subset of the data analyzed in this work.Comment: Published at http://dx.doi.org/10.1214/15-AOAS861 in the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Introduction. Pour une nouvelle approche de la politisation des campagnes

International audienceComment la démocratie ou le communisme se sont-ils répandus jusqu’au coeur des villages français ? Depuis plusieurs décennies, historiens et politistesse sont penchés sur le siècle et demi qui s’étend de la Révolution française aux années 1930, le temps de la politisation des campagnes. Quinze jeuneschercheurs se proposent de recoller quelques morceaux du “miroir brisé” des réflexions sur la politisation, en reprenant le dossier à échelle fine, celle desacteurs (individuels ou collectifs) et de leurs stratégies d’action. Qui sont les passeurs d’idées politiques nouvelles ? Quelles formes ont revêtu leursmédiations ? Comment leurs efforts ont-ils été reçus ? C’est à ces questions que s’attache à répondre cet ouvrage. Qu’ils soient des passeurs-missionnaires (voire des missionnaires armés) ou des passeurs-notables, c’est en mobilisant une grammaire d’action transmise et/ou inventée que les passeurs d’idéespolitiques nouvelles ont pu porter, au village, les dynamiques au temps long qui ont façonné la géopolitique de la France contemporaine

A simplified table using validated diagnostic criteria is effective to improve characterization of colorectal polyps: the CONECCT teaching program

International audienceIntroduction and study aims Accurate real-time endoscopic characterization of colorectal polyps is key to choosing the most appropriate treatment. Mastering the currently available classifications is challenging. We used validated criteria for these classifications to create a single table, named CONECCT, and evaluated the impact of a teaching program based on this tool.Methods A prospective multicenter study involving GI fellows and attending physicians was conducted. During the first session, each trainee completed a pretest consisting in histological prediction and choice of treatment of 20 colorectal polyps still frames. This was followed by a 30-minute course on the CONECCT table, before taking a post-test using the same still frames reshuffled. During a second session at 3 – 6 months, a last test (T3 M) was performed, including these same still frames and 20 new ones.Results A total 419 participants followed the teaching program between April 2017 and April 2018. The mean proportion of correctly predicted/treated lesions improved significantly from pretest to post-test and to T3 M, from 51.0 % to 74.0 % and to 66.6 % respectively (P < 0.001). Between pretest and post-test, 343 (86.6 %) trainees improved, and 153 (75.4 %) at T3 M. Significant improvement occurred for each subtype of polyp for fellows and attending physicians. Between the two sessions, trainees continued to progress in the histology prediction and treatment choice of polyps CONECCT IIA. Over-treatment decreased significantly from 30.1 % to 15.5 % at post-test and to 18.5 % at T3 M (P < 0.001).Conclusion The CONECCT teaching program is effective to improve the histology prediction and the treatment choice by gastroenterologists, for each subtype of colorectal polyp

Use of pluripotent stem cells to model spinal muscular atrophy

Les cellules souches pluripotentes humaines (hPSC) ont pour caractéristiques principales l'auto-renouvellement permettant de les avoir de manière quasi-illimité ainsi qu'un potentiel de différenciation, qui en théorie, peut permettre de générer l’ensemble de cellules de l'organisme. Ces deux caractéristiques en font un outil de choix pour une utilisation en médecine régénérative, disséquer certains mécanismes du développement humain, l'étude de maladies génétiques et la recherche de nouveaux médicaments. Durant mes travaux de thèse, j'ai utilisé les hPSC afin de mettre en place un nouveau modèle d'étude de l'amyotrophie spinale infantile (SMA). La SMA est une maladie neurodégénérative due à la mort spécifique des motoneurones (MN) de la moelle épinière qui provoque une atrophie des muscles striés. La première étape a consisté à la mise en place d'un protocole de différenciation efficace en motoneurones à partir des hPSC. A l'issue d'un criblage combinatoire de morphogènes, nous avons identifié une condition permettant la production de motoneurones spinaux de façon efficace (70%) et rapide (14 jours). Des conditions de génération de motoneurones craniaux (50%), sensitifs (65%) et inter-neurones (75%) ont également été identifiées. Ce protocole de différenciation optimisé a ensuite été appliqué sur des lignées de cellules souches induites à la pluripotence (hIPS) reprogrammées à partir de fibroblastes porteurs de la mutation causale de la SMA ainsi que sur des fibroblastes contrôles. Nous avons mis en place un système d'étude des motoneurones en plaque 384 afin d'étudier le phénotype de dégénérescence spécifique des MN-SMA sur des cultures à long terme, via des approches d'analyse à haut débit. Nos travaux montrent que notre modèle de la SMA récapitule certains des phénotypes connus de la SMA et peut être utilisé pour des approches de criblage pharmacologique. En parallèle, nous avons également utilisé les caractéristiques des hPSC afin d'étudier un mécanisme intervenant dans les étapes précoces du développement embryonnaire. Nous avons travaillé en collaboration avec l'équipe du Dr. Rougeulle afin d'étudier les mécanismes de l'inactivation du chromosome X. Nous avons notamment déterminé l'implication du facteur Xact dans la mise en place des évènements menant à la ré-activation du chromosome X.En conclusion, les hPSC sont donc devenue des outils primordiaux pour la modélisation, qu'elle soit développementale ou pathologique et devraient permettre d'accélérer la compréhension des mécanismes physiologiques.Human pluripotent stem cells (hPSCs) are characterized by self-renewal and pluripotency abilities that refer to the capacity to proliferate indefinitively without commitment in vitro and to the ability to differentiate into multiple and specialized cell lineages. hPSCs are a useful tool for regenerative medicine, pathological modelling and new therapeutic molecule identification.My thesis project mainly focused on the development of a new cellular model for the study of spinal muscular atrophy (SMA). SMA is mainly characterized by a specific loss of spinal motor-neurons (sMN) that induces a progressive muscle weakness. The initial objective has been to define a protocol allowing the differentiation of sMN starting from hPSC. Using combinatorial analysis, we identified experimental condition that induced an efficient (70%) and rapid (14 days) generation of sMN. In parallel, we setted up the condition needed for the specification of different subtype of MN, such as spinal interneurons (77%) and sensory neurons (64%) in the same timeline.Then, we used human induced pluripotent stem cells (hIPS) from skin biopsies of SMA patients and unaffected fibroblasts. Characterization of the MNs viability was performed in 384 wells plates with high throughput screening. Moreover, our new system allowed us to reproduce in well characterized human PSC-derived MNs specific phenotype described for SMA thus providing a new tool for HT pharmacological screening and drug discovery. In addition, in collaboration with Dr.Rougeulle, we used hPSC to study specific mechanism occurring during early stages of embryonic development. In particular, we characterized the implication of Xact in the reactivation of chromosome X

Les passeurs d'idées politiques nouvelles au village. De la Révolution aux années 1930

International audienceComment la démocratie ou le communisme se sont-ils répandus jusqu’au coeur des villages français ? Depuis plusieurs décennies, historiens et politistes se sont penchés sur le siècle et demi qui s’étend de la Révolution française aux années 1930, le temps de la politisation des campagnes. Quinze jeunes chercheurs se proposent de recoller quelques morceaux du “miroir brisé” des réflexions sur la politisation, en reprenant le dossier à échelle fine, celle des acteurs (individuels ou collectifs) et de leurs stratégies d’action. Qui sont les passeurs d’idées politiques nouvelles ? Quelles formes ont revêtu leurs médiations ? Comment leurs efforts ont-ils été reçus ? C’est à ces questions que s’attache à répondre cet ouvrage. Qu’ils soient des passeurs-missionnaires (voire des missionnaires armés) ou des passeurs-notables, c’est en mobilisant une grammaire d’action transmise et/ou inventée que les passeurs d’idées politiques nouvelles ont pu porter, au village, les dynamiques au temps long qui ont façonné la géopolitique de la France contemporaine

Le modèle DFM pour une analyse comparative des systèmes de vélos en libre service

International audienceBike sharing systems (BSSs) have become a means of sustainable inter-modal transport and are now proposed in many cities worldwide. Most BSSs also provide 1open access to their data, particularly to real-time status reports on their bike stations. The analysis of the mass of data generated by such systems is of particular interest to BSS providers to update system structures and policies. This work was motivated by interest in analyzing and comparing several European BSSs to identify common operating patterns in BSSs and to propose practical solutions to avoid potential issues. Our approach relies on the identification of common patterns between and within systems. To this end, a model- based clustering method, called FunFEM, for time series (or more generally functional data) is developed. It is based on a functional mixture model that allows the clustering of the data in a discriminative functional subspace. This model presents the advantage in this context to be parsimonious and to allow the visualization of the clustered systems. Numerical experiments confirm the good behavior of FunFEM, particularly compared to state-of-the-art methods. The application of FunFEM to BSS data from JCDecaux and the Transport for London Initiative allows us to identify 10 general patterns, including pathological ones, and to propose practical improvement strategies based on the system comparison. The visualization of the clustered data within the discriminative subspace turns out to be particularly informative regarding the system efficiency. The proposed methodology is implemented in a package for the R software, named funFEM, which is available on the CRAN. The package also provides a subset of the data analyzed in this work

Tests d'outils innovants pour la caractérisation haute résolution des sites pollués

International audienceLa caractérisation de la pollution du milieu souterrain d’un site est un enjeu essentiel pour définir les actions de remédiation et atteindre les objectifs associés. Parmi les verrous récurrents à cette caractérisation, se situent la complexité des sites, les hétérogénéités géologiques des sols, les grandes différences de comportement et de mobilité des polluants d’intérêts. La compréhension de la distribution des polluants et des contextes physiques dans lesquels ils se situent représente une clé du succès d’une opération de remédiation.La caractérisation des pollutions, par l’intermédiaire d’un prélèvement classique d’eaux souterraines réalisé dans un piézomètre, fournit généralement une information trop partielle pour permettre d’établir un schéma conceptuel de qualité des milieux complexes. Dans pareil cas, des prélèvements multi niveaux et l’acquisition de données complémentaires aux données de qualité chimiques des eaux sont indispensables.Cette étude organise un atelier participatif pour tester différents outils innovants de caractérisation détaillée des matrices souterraines :Mesures de flux de nappe (sens, vitesse …),Mesures multiniveaux de la matrice eau (concentrations, flux…).Les résultats attendus portent sur des connaissances partagées des périmètres d’utilisation de ces outils (typologies de site, géologie, hydrogéologie, contaminants…), des conditions opérationnelles de leur mise en œuvre (conditions d’accès à la technique, facilités d’utilisation, compétences nécessaires, coûts associés, …), de leurs performances techniques (précisions, incertitudes, quantifications, …), de leurs limites (selon les différents contextes de sites…).Cette comparaison doit favoriser l’appropriation d’outils innovants (français et étrangers) pour une caractérisation détaillée de sites pollués (D-L-NAPL), permettant de mieux comprendre les dynamiques et le fonctionnement des systèmes. Elle pourrait permettre de proposer des schémas conceptuels plus précis pour une meilleure connaissance des transferts et une meilleure conception des opérations de remédiation

Dyspnea and the electromyographic activity of inspiratory muscles during weaning from mechanical ventilation

International audienceAbstract Rationale Dyspnea, a key symptom of acute respiratory failure, is not among the criteria for spontaneous breathing trial (SBT) failure. Here, we sought (1) to determine whether dyspnea is a reliable failure criterion for SBT failure; (2) to quantify the relationship between dyspnea and the respective electromyographic activity of the diaphragm (EMGdi), the parasternal (EMGpa) and the Alae nasi (EMGan). Methods Mechanically ventilated patients undergoing an SBT were included. Dyspnea intensity was measured by the Dyspnea-Visual Analogic Scale (Dyspnea-VAS) at the initiation and end of the SBT. During the 30-min SBT or until SBT failure, the EMGdi was continuously measured with a multi-electrode nasogastric catheter and the EMGan and EMGpa with surface electrodes. Results Thirty-one patients were included, SAPS 2 (median [interquartile range]) 53 (37‒74), mechanically ventilated for 6 (3‒10) days. Seventeen patients (45%) failed the SBT. The increase in Dyspnea-VAS along the SBT was higher in patients who failed (6 [4‒8] cm) than in those who passed (0 [0‒1] cm, p = 0.01). The area under the receiver operating characteristics curve for Dyspnea-VAS was 0.909 (0.786–1.032). The increase in Dyspnea-VAS was significantly correlated to the increase in EMGan (Rho = 0.42 [0.04‒0.70], p < 0.05), but not to the increase in EMGpa (Rho = − 0.121 [− 0.495 to − 0.290], p = 0.555) and EMGdi (Rho = − 0.26 [− 0.68 to 0.28], p = 0.289). Conclusion Dyspnea is a reliable criterion of SBT failure, suggesting that Dyspnea-VAS could be used as a monitoring tool of the SBT. In addition, dyspnea seems to be more closely related to the electromyographic activity of the Alae nasi than of the diaphragm

Combinatorial analysis of developmental cues efficiently converts human pluripotent stem cells into multiple neuronal subtypes

International audienceSpecification of cell identity during development depends on exposure of cells to sequences of extrinsic cues delivered at precise times and concentrations. Identification of combinations of patterning molecules that control cell fate is essential for the effective use of human pluripotent stem cells (hPSCs) for basic and translational studies. Here we describe a scalable, automated approach to systematically test the combinatorial actions of small molecules for the targeted differentiation of hPSCs. Applied to the generation of neuronal subtypes, this analysis revealed an unappreciated role for canonical Wnt signaling in specifying motor neuron diversity from hPSCs and allowed us to define rapid (14 days), efficient procedures to generate spinal and cranial motor neurons as well as spinal interneurons and sensory neurons. Our systematic approach to improving hPSC-targeted differentiation should facilitate disease modeling studies and drug screening assays

Impact of the COVID-19 Pandemic on Complex Aortic Aneurysm Surgery

International audienceIntroduction: This study aimed to evaluate the impact of COVID on total case load and peri-operative outcomes in patients undergoing open surgical repair (OSR) and endovascular repair (ER) of complex aortic aneurysms (cAAs). Methods: A single-center retrospective analysis of prospective data of patients managed with elective cAA ER or OSR from January 2018 to December 2021 was conducted. A comparative analysis on the impact of the COVID-19 pandemic on the case volume and on the 30-day outcomes was assessed using time periods, before (2018–2019) and during the pandemic (2020–2021). Results: During the 4-year study period, 255 patients with cAA were managed with ER and 576 with OSR. The pandemic did not reduce the cAA ER volume (p=0.12), but a statistically significant reduction in OSR case load was recorded (p=0.04). Following OSR, hospital length of stay (11.1 vs 10.3 days), and early mortality (6.94% vs 4.63%), were similar before and during the pandemic. In the ER cohort, baseline characteristics, early mortality (3.6% vs 4.1%, p=0.976), and morbidity (10% vs 14%, p=0.44), were comparable during the 2 periods. For ER cases, the hospital and intensive care unit (ICU) stay both decreased significantly (8±8–6±7 days, p<0.001 and 2±4 vs 1±6 days p=0.01, respectively) during the pandemic. Conclusion: Resource pressures drove modifications in clinical practice to reduce the length of hospitalization, without compromising the clinical outcomes, in patients undergoing ER of cAA. This modification was not effective in patients undergoing OSR that resulted in a significant decrease of this activity. Clinical Impact The pandemic did not reduce complex endovascular repair (ER) volume (p=0.12) while a significant reduction in open surgical repair (OSR) case load was recorded (p=0.04). For the endovascular cohort, early mortality (p=0.976) and morbidity (p=0.44) remained stable, while the hospital and intensive care unit (ICU) stay decreased (p<0.001 and p=0.01, respectively) during the pandemic