Molecular Phylogenetics of Thecata (Hydrozoa, Cnidaria) Reveals Long-Term Maintenance of Life History Traits despite High Frequency of Recent Character Changes

Two fundamental life cycle types are recognized among hydrozoan cnidarians, the benthic (generally colonial) polyp stage either producing pelagic sexual medusae or directly releasing gametes elaborated from an attached gonophore. The existence of intermediate forms, with polyps producing simple medusoids, has been classically considered compelling evidence in favor of phyletic gradualism. In order to gain insights about the evolution of hydrozoan life history traits, we inferred phylogenetic relationships of 142 species of Thecata (= Leptothecata, Leptomedusae), the most species-rich hydrozoan group, using 3 different ribosomal RNA markers (16S, 18S, and 28S). In conflict with morphology-derived classifications, most thecate species fell in 2 well-supported clades named here Statocysta and Macrocolonia. We inferred many independent medusa losses among Statocysta. Several instances of secondary regain of medusoids (but not of full medusa) from medusa-less ancestors were supported among Macrocolonia. Furthermore, life cycle character changes were significantly correlated with changes affecting colony shape. For both traits, changes did not reflect graded and progressive loss or gain of complexity. They were concentrated in recent branches, with intermediate character states being relatively short lived at a large evolutionary scale. This punctuational pattern supports the existence of 2 alternative stable evolutionary strategies: simple stolonal colonies with medusae (the ancestral strategy, seen in most Statocysta species) versus large complex colonies with fixed gonophores (the derived strategy, seen in most Macrocolonia species). Hypotheses of species selection are proposed to explain the apparent long-term stability of these life history traits despite a high frequency of character change. Notably, maintenance of the medusa across geological time in Statocysta might be due to higher extinction rates for species that have lost this dispersive stag

Practical Relativistic Zero-Knowledge for NP

In a Multi-Prover environment, how little spatial separation is sufficient to assert the validity of an NP statement in Perfect Zero-Knowledge ? We exhibit a set of two novel Zero-Knowledge protocols for the 3-COLorability problem that use two (local) provers or three (entangled) provers and only require exchanging one edge and two bits with two trits per prover. This greatly improves the ability to prove Zero-Knowledge statements on very short distances with very basic communication gear

Practical Relativistic Zero-Knowledge for NP

In this work we consider the following problem: in a Multi-Prover environment, how close can we get to prove the validity of an NP statement in Zero-Knowledge ? We exhibit a set of two novel Zero-Knowledge protocols for the 3-COLorability problem that use two (local) provers or three (entangled) provers and only require them to reply two trits each. This greatly improves the ability to prove Zero-Knowledge statements on very short distances with very minimal equipment.Comment: Submitted to ITC 202

Efficient enumeration of maximal split subgraphs and sub-cographs and related classes

In this paper, we are interested in algorithms that take in input an arbitrary graph $G$, and that enumerate in output all the (inclusion-wise) maximal "subgraphs" of $G$ which fulfil a given property $\Pi$. All over this paper, we study several different properties $\Pi$, and the notion of subgraph under consideration (induced or not) will vary from a result to another. More precisely, we present efficient algorithms to list all maximal split subgraphs, sub-cographs and some subclasses of cographs of a given input graph. All the algorithms presented here run in polynomial delay, and moreover for split graphs it only requires polynomial space. In order to develop an algorithm for maximal split (edge-)subgraphs, we establish a bijection between the maximal split subgraphs and the maximal independent sets of an auxiliary graph. For cographs and some subclasses , the algorithms rely on a framework recently introduced by Conte & Uno called Proximity Search. Finally we consider the extension problem, which consists in deciding if there exists a maximal induced subgraph satisfying a property $\Pi$ that contains a set of prescribed vertices and that avoids another set of vertices. We show that this problem is NP-complete for every "interesting" hereditary property $\Pi$. We extend the hardness result to some specific edge version of the extension problem

Comparaison de méthodes de recalage visuel de modèles 3D pour l'orthodontie

National audienceIn this paper, we compare two vision registration methods of 3D models to develop a main tool for orthodontics based on the virtual occlusion of two dental casts. For that purpose, we process photos of the patient mouth and match points between pictures and dental geometrical models. From a set of 2D/3D matches of the two arcades, we calculate the projection matrix, and after we do the registration of the mandible under the maxillary through a rigid transformation. Two methods with or without the knowledge of camera intrinsic parameters are compared. Minimizing the reprojection errors, we perform the registration of the mandible. Tests are carried out on virtual data and real images. Using a virtual case, assumed as perfect, we evaluate the robustness against noise and the increase of performance using several views. Projection matrices and registration are evaluated, respectively, by reprojection errors and the recorded differences on the 6 parameters of rigid transformation compared with the reference pose.Dans cet article, nous comparons des méthodes de recalage de modèles 3D par vision pour développer un outil essentiel en orthodontie : la mise en occlusion virtuelle des deux moulages des mâchoires. Pour cela, on utilise des photos de la bouche du patient et des points mis en correspondance entre les images et les modèles dentaires surfaciques. A partir d'un ensemble de correspondances 2D/3D disponibles établies sur les deux arcades, on calcule la matrice de projection, puis on effectue le recalage de la mandibule sous le maxillaire en estimant une transformation rigide. Deux approches sont comparées selon que l'on dispose ou non de la connaissance des paramètres intrinsèques de la caméra. Le recalage de la mandibule est ensuite estimé en minimisant l'erreur de reprojection. Les tests sont effectués sur des données virtuelles puis des images réelles. A partir d'un cas virtuel " parfait ", nous évaluons la dégradation des performances avec l'ajout de bruit et l'intérêt de combiner plusieurs vues. Les matrices de projections estimées sont évaluées par les erreurs de reprojection et les recalages par les écarts constatés sur les 6 paramètres de la transformation rigide par rapport à un positionnement de référence

Multi-Phase Task-Based HPC Applications: Quickly Learning how to Run Fast

International audienceParallel applications performance strongly depends on the number of resources. Although adding new nodes usually reduces execution time, excessive amounts are often detrimental as they incur substantial communication overhead, which is difficult to anticipate. Characteristics like network contention, data distribution methods, synchronizations, and how communications and computations overlap generally impact the performance. Finding the correct number of resources can thus be particularly tricky for multi-phase applications as each phase may have very different needs, and the popularization of hybrid (CPU+GPU) machines and heterogeneous partitions makes it even more difficult. In this paper, we study and propose, in the context of a task-based GeoStatistic application, strategies for the application to actively learn and adapt to the best set of heterogeneous nodes it has access to. We propose strategies that use the Gaussian Process method with trends, bound mechanisms for reducing the search space, and heterogeneous behavior modeling. We compare these methods with traditional exploration strategies in 16 different machines scenarios. In the end, the proposed strategies are able to gain up to ≈51% compared to the standard case of using all the nodes while having low overhead

Rôle de l'autoréactivité sur les capacités suppressives des lymphocytes T régulateurs CD4+ Foxp3+

La plupart des lymphocytes T régulateurs CD4+ Foxp3+ (Tregs) sont générés dans le thymus. Plusieurs études suggèrent fortement que le développement des Tregs est dû à la forte affinité de leur TCR pour le soi (complexes peptide du soi-CMH II ) présenté dans le thymus. Après avoir migré à la périphérie, les Tregs continuent d interagir avec le soi et l expression de Foxp3 est considérée comme nécessaire et suffisante pour maintenir le programme de transcription nécessaire aux fonctions suppressives de ces cellules en périphérie. En utilisant deux models expérimentaux chez la souris, notre étude démontre l importance des interactions continues avec le soi pour maintenir les capacités suppressives des Tregs à la périphérie. L absence d interactions avec le soi aboutit rapidement à une altération du phénotype des Tregs, de leur capacité à produire certaines cytokines et modifie également leur signature transcriptionnelle. De façon intéressante, nous avons observé que l absence d interaction avec le soi n affecte pas le niveau d expression de Foxp3 mais que la reconnaissance du soi induit une signature transcriptionnelle unique et des caractéristiques fonctionnelles qui ne sont pas liées à Foxp3. Dans une seconde étude, nous avons mis en évidence que, chez la souris jeune adulte, l expression de Ly-6C permet d identifier deux sous-populations de Tregs distinctes présentant des différences phénotypiques et fonctionnelles. En particulier, nous avons observé que les Tregs Ly-6C- présentent un phénotype plus activé et régulateur que leurs homologues Ly-6C+ et que seules les premières sont fonctionnelles in vitro et in vivo. Nous avons également montré un lien étroit entre expression de Ly-6C et autoréactivité, les Tregs Ly-6C- recevant plus de signaux du TCR que les Tregs Ly-6C+. Finalement, nous avons observé que seuls les Tregs Ly-6C- se maintiennent à la périphérie avec le temps, suggérant l existence d une sélection périphérique permettant la survie préférentielle des Tregs les plus fonctionnels. Au cours de ma thèse, nous avons ainsi pu démontrer que les interactions avec le soi étaient indispensables et nécessaires pour la fonctionnalité, le phénotype et l homéostasie des Tregs.Most regulatory T cells CD4 + Foxp3 + ( Tregs ) are generated in the thymus. Several studies strongly suggest that the development of Tregs is due to the high affinity of their TCR for itself (complex " self peptide - MHC II ') shown in the thymus . After migrating to the periphery, Tregs continue to interact with the self and the expression of Foxp3 is considered necessary and sufficient to maintain the transcriptional program required for suppressive function of these cells in the periphery. Using two experimental models in mice, our study demonstrates the importance of ongoing interactions with itself to keep the suppressive capacity of Tregs in the periphery. The lack of interaction with the so quickly leads to an altered phenotype of Tregs , their ability to produce cytokines and also changes their transcriptional signature. Interestingly , we observed that the lack of interaction with the so does not affect the expression level of Foxp3 but self-recognition induces a unique transcriptional signature and functional characteristics that are not related to Foxp3 . In a second study, we demonstrated that in young adult mice , the expression of Ly- 6C identifies two distinct subpopulations of Tregs with phenotypic and functional differences . In particular, we observed that Tregs Ly- 6C- have a more activated phenotype and control than their counterparts Ly- 6C + and only the former are functional in vitro and in vivo. We have also shown a strong link between expression of Ly- 6C and autoreactivity , Tregs Ly- 6C- receiving over TCR signals that Ly -6C + Tregs . Finally , we observed that only Tregs Ly- 6C- remain at the periphery over time , suggesting the existence of a selection device for the preferential survival of the most functional Tregs . During my thesis, we were able to demonstrate that interactions with the self were essential and necessary for the functionality, phenotype and homeostasis of Tregs.PARIS5-Bibliotheque electronique (751069902) / SudocSudocFranceF

Communication-Aware Load Balancing of the LU Factorization over Heterogeneous Clusters

International audienceLarge clusters and supercomputers are rapidly evolving and may be subject to regular hardware updates that increase the chances of becoming heterogeneous. Homogeneous clusters may also have variable performance capabilities due to processor manufacturing, or even partitions equipped with different types of accelerators. Data distribution over heterogeneous nodes is very challenging but essential to exploit all resources efficiently. In this article, we build upon task-based runtimes' flexibility to study the interplay between static communication-aware data distribution strategies and dynamic scheduling of the linear algebra LU factorization over heterogeneous sets of hybrid nodes. We propose two techniques derived from the state-of-the-art 1D×1D data distributions. First, to use fewer computing nodes towards the end to better match performance bounds and save computing power. Second, to carefully move a few blocks between nodes to optimize even further the load balancing among nodes. We also demonstrate how 1D×1D data distributions, tailored for heterogeneous nodes, can scale better with homogeneous clusters than classical block-cyclic distributions. Validation is carried out both in real and in simulated environments under homogeneous and heterogeneous platforms, demonstrating compelling performance improvements