GXcast : une généralisation du protocole Xcast

journal électroniqueNational audienceDans ce papier, nous étudions une généralisation du protocole Xcast. Après avoir introduit les deux protocoles Xcast et Xcast+, leurs avantages et leurs inconvénients, nous présentons notre protocole GXcast : le format d'un paquet GXcast et l'algorithme de routage. La résistance au facteur d'échelle du protocole GXcast est comparée à celle d'autres protocoles multicast. Nous proposons notamment une fonction permettant de réduire les inconvénients de ce type de protocoles et évaluons le protocole GXcast en termes de surcoûtet de délai. Les résultats de simulation confirment notre analyse

Distributed Multicast Tree Aggregation

Multicast is not scalable mainly due to the number of forwarding states and control overhead required to maintain trees. Tree aggregation reduces the number of multicast forwarding states and the tree maintenance overhead by allowing several multicast groups to share the same delivery tree. In this paper, we exhibit several drawbacks of the existing protocols: the latency to manage group dynamics is high, the managers are critical points of failures and some group-specific entries are stored unnecessarily. Then, we propose a new distributed protocol that significantly reduces the number of control messages and limits the number of trees within a domain. By simulations, we show that our protocol achieves good performance and outperforms the previous known distributed algorithm. // Le Multicast n'est pas encore bien déployé dans Internet. Les deux raisons principales qui freinent son déploiement sont : le nombre d'états de routage important qui dépend du nombre de groupes et le nombre de messages de contrôle nécessaires pour maintenir les arbres multicast dans un domaine de routage. L'agrégation d'arbres multicast est un protocole qui permet de résoudre ces deux problèmes en permettant à plusieurs groupes multicast d'utiliser le même arbre de routage. Dans ce papier, nous détaillons plusieurs inconvénients concernant les protocoles rééalisant l'agrégation d'arbres. En effet, dans ces protocoles, la latence pour gérer la dynamicité des groupes est grande, les gestionnaires d'agrégation sont des points critiques dans le cas de pannes et des entrées spécifiques aux groupes sont stoquées inutilement. Nous proposons un nouveau protocole distribué qui réduit le nombre de messages de contrôle envoyés et qui limite le nombre d'arbres dans un domaine. Par des simulations, nous prouvons que notre protocole a de bien meilleures performances que le tout dernier protocole distribué connu

Evaluation of sorghum grain quality for QTL analysis and Marker Assisted Recurrent Selection (MARS) : [P1121]

Sorghum breeding in Mali mostly focuses on varieties for human consumption. Even if most of breeding efforts concentrate on productivity and adaptation, grain quality is a very important aspect to consider for improved material to be adopted and successful. One major traditional use of sorghum in West-Africa is the tô, a thick porridge prepared from sorghum flour. We evaluated several important technological traits involved in tô quality (pericarp thickness, dehulling yield, endosperm texture, grain roundness and size, amylose content, presence or not of anthocyan) in two F3 populations of 400 families each. Near infrared reflectance spectroscopy (NIRS) was investigated as an indirect method to evaluate some of these traits on sorghum grain rather than on flour. QTLs for these traits were detected and the interaction between QTLs evaluated. The consistency and color of tô were evaluated on mini-tô prepared from 200 families. QTLs for tô consistency were compared with those for technological traits. Several QTLs were detected including major QTLs, explaining 92% of the variation for the presence of anthocyan, 55% for pericarp thickness, and 22% for dehulling yield. A QTL explaining 19% of grain roundness and 11% for endosperm texture was also found. These QTLs are being used together with QTLs for grain yield, flowering time, plant and panicle morphology, to select varieties adapted for making good tô and combining productivity and grain quality through integrated marker assisted recurrent selection

Reconstruction of eye movements during blinks

In eye movement research in reading, the amount of data plays a crucial role for the validation of results. A methodological problem for the analysis of the eye movement in reading are blinks, when readers close their eyes. Blinking rate increases with increasing reading time, resulting in high data losses, especially for older adults or reading impaired subjects. We present a method, based on the symbolic sequence dynamics of the eye movements, that reconstructs the horizontal position of the eyes while the reader blinks. The method makes use of an observed fact that the movements of the eyes before closing or after opening contain information about the eyes movements during blinks. Test results indicate that our reconstruction method is superior to methods that use simpler interpolation approaches. In addition, analyses of the reconstructed data show no significant deviation from the usual behavior observed in readers

L'énergie éolienne en Auvergne : questions sur une ressource en plein essor

International audienceSouvent présentée comme une énergie renouvelable dont le développement serait indispensable pour un avenir plus respectueux de l’environnement, l’énergie éolienne, qui commence tout juste à se développer en Auvergne, nous pose des questions. Comment les projets auvergnats s’inscrivent-ils dans les dynamiques nationales ? Jusqu’où l’éolien peut-il se développer dans la région, quel est son potentiel ? Quels sont les rôles et les stratégies des différents acteurs concernés ?Quelles sont les limites d’une telle dynamique, et les résistances qu’elle rencontre

Self-Supervised Learning for Cardiac MR Image Segmentation by Anatomical Position Prediction

In the recent years, convolutional neural networks have transformed the field of medical image analysis due to their capacity to learn discriminative image features for a variety of classification and regression tasks. However, successfully learning these features requires a large amount of manually annotated data, which is expensive to acquire and limited by the available resources of expert image analysts. Therefore, unsupervised, weakly-supervised and self-supervised feature learning techniques receive a lot of attention, which aim to utilise the vast amount of available data, while at the same time avoid or substantially reduce the effort of manual annotation. In this paper, we propose a novel way for training a cardiac MR image segmentation network, in which features are learnt in a self-supervised manner by predicting anatomical positions. The anatomical positions serve as a supervisory signal and do not require extra manual annotation. We demonstrate that this seemingly simple task provides a strong signal for feature learning and with self-supervised learning, we achieve a high segmentation accuracy that is better than or comparable to a U-net trained from scratch, especially at a small data setting. When only five annotated subjects are available, the proposed method improves the mean Dice metric from 0.811 to 0.852 for short-axis image segmentation, compared to the baseline U-net

La couverture forestière du Haut Livradois : marque de déclin ou opportunité de développement ?

Deuxième prix du concours de posters scientifiques du festivalInternational audienceSous l’Ancien Régime, le Haut Livradois était l’une des montagnes les plus densément peuplées de France, offrant des paysages largement ouverts et dominés par l’activité agricole. Aujourd’hui, 68 % de la surface du Haut Livradois est boisée, et le taux de boisement dépasse même 80 % dans certaines communes. Ainsi, l’occupation de l’espace a profondément évolué au cours du vingtième siècle. Au fil des décennies, le couvert forestier s’est étendu de manière anarchique dans le Haut Livradois. Le paysage actuel est façonné par des boisements incontrôlés. L’économie autour de la filière bois reste peu développée. Des actions politiques tentent d’améliorer la situation

Efficient Protection of Many-to-One Communications

International audienceThe dependability of a network is its ability to cope with failures , i.e., to maintain established connections even in case of failures. IP routing protocols (such as OSPF and RIP) do not fit the dependability objectives of today applications. Moreover, forwarding techniques based on destination address (like IP) induce many-to-one connections. If a dependable connection is needed, all primary paths and protections having the same destination must be established in a coordinated way. In this paper, we propose a fault recovery for many-to-one connections based on a cold (preplanned) protection. The main advantage of our approach is that the recovery in case of failures is achieved within a short delay. Additionally, with respect to other approaches, the dependability of the routing scheme is increased in the way that it statistically copes with many failures. The algorithm we propose computes an efficient backup for an arbitrary primary tree using an improved multi-tree algorithm