On the capacity achieving covariance matrix for Rician MIMO channels: an asymptotic approach

The capacity-achieving input covariance matrices for coherent block-fading correlated MIMO Rician channels are determined. In this case, no closed-form expressions for the eigenvectors of the optimum input covariance matrix are available. An approximation of the average mutual information is evaluated in this paper in the asymptotic regime where the number of transmit and receive antennas converge to $+\infty$. New results related to the accuracy of the corresponding large system approximation are provided. An attractive optimization algorithm of this approximation is proposed and we establish that it yields an effective way to compute the capacity achieving covariance matrix for the average mutual information. Finally, numerical simulation results show that, even for a moderate number of transmit and receive antennas, the new approach provides the same results as direct maximization approaches of the average mutual information, while being much more computationally attractive.Comment: 56 pp. Extended version of the published article in IEEE Inf. Th. (march 2010) with more proof

Hazard estimation for censored data contaminated with additive measurement error: application to length of pregnancy

International audienceWe consider random variables which can be subject to both censoring and measurement errors. We focus on the case where the measurement errors affect both the variable of interest and the censoring variable, which is the case of the timing of spontaneous delivery among pregnant women. We propose an estimation strategy to estimate the hazard rate of the underlying variable of interest. We explain the model and this strategy and provide L2-risk bound for the data driven resulting estimator. Simulations illustrate the performances of the estimator. Lastly, the method is applied to a real data set of length of pregnanc

Deconvolution estimation of onset of pregnancy with replicate observations

International audienceExcept in the specific case of in vitro fertilization, the precise date of onset of pregnancy is unknown. In clinical practice, the date of pregnancy may only be estimated, and most commonly from ultrasound biometric measurements of the embryo. Denoting $X$ the interval between last menstrual period and true onset of pregnancy and $Y$ the interval between last menstrual period and the date estimated by ultrasound, we wish to estimate the density \fx of $X$. Only noisy observations $Y_{j}=X_{j}+\varepsilon_{j}, j=1,\dots,n$ are observed and the density $f_\varepsilon$ of $\varepsilon$ is unknown. Because the noise itself cannot be sampled for the estimation of its density, we consider the specific setting of replicate noisy observations $Y_{-j1}=X_{-j}+\varepsilon_{-j1}$ and $Y_{-j2}=X_{-j}+\varepsilon_{-j2}$, $j=1,\dots,M$. We suggest an adaptive non-parametric estimator of \fx built following a deconvolution device. Convergence rates are studied and compared to other settings that do not involve replicates. Lastly, we estimate the density \fx in spontaneous pregnancies with an estimation of the noise obtained from replicate observations in twin pregnancies

A CRITICAL STUDY ON GRAMMAR LESSONS TEACHING METHODOLOGY AND THEIR PRACTICE ACTIVITIES AS IMPLEMENTED IN THE COMMUNICATIVE CLASSROOM

Grammar lessons teaching methodology and their practice activities as implemented in the communicative classroom is the success of the teaching-learning process in which learners learning will result in a satisfactory school achievement. To achieve the goal, library research, observation, questionnaire and interview were used to collect theoretical and field data. The aim of the whole exercise was to investigate into how teachers of English at secondary schools handle grammar lessons and how they offer their practice activities, as far as communication is concerned. An analysis of the different preparation cards and field data revealed that Grammar lessons require sufficient practice activities and competence in the teaching of the English language so as to help learners to use language for communication. The findings led to some suggestions and recommendations in the sense of helping both learners and teachers to practice the language.  Article visualizations

Architecture de rebalancement dynamique pour jeux massivement multijoueurs en ligne fonctionnant sur réseaux pair-à-pair

Résumé L'industrie des jeux vidéos a connu une forte explosion ces dernières années. En particulier, un tout nouveau genre de jeux, les jeux massivement multijoueurs en ligne, a connu une forte popularisation. Ces jeux se caractérisent par un environnement virtuel immense et persistant qui est continuellement actif et évolutif. À la différence des autres jeux, les jeux massivement multijoueurs en ligne intègrent des milliers de joueurs qui participent au sein du même univers commun à tous. À l'heure actuelle, la gestion informatique de tels univers nécessite beaucoup de ressources et constitue un défi de taille afin de s'adapter au nombre toujours croissant de joueurs. Le modèle client-serveur est actuellement utilisé, mais ce dernier s'avère éventuellement limité puisqu'il arrive un point où la puissance d'une seule machine ne suffit plus à assurer la prise en charge de tous les joueurs. L'utilisation d'un modèle pair-à-pair constitue une approche intéressante puisqu'il permet de redistribuer la charge de traitement requise pour assurer la maintenance du jeu aux noeuds-joueurs eux-mêmes. Certaines approches pair-à-pair ont été proposées dans la littérature. Nous proposons d'aller un peu plus loin en proposant une approche hybride flexible capable de s'adapter automatiquement aux conditions actuelles en cours de jeu. Plus précisément, notre approche propose de découper dynamiquement le territoire du jeu et d'assigner chaque parcelle à un noeud serveur choisi arbitrairement parmi les joueurs participant actuellement au jeu. Le modèle propose ensuite d'analyser continuellement la charge réseau imposée à chaque noeud et d'appliquer automatiquement des opérations de rebalancement pour redistribuer la charge afin d'assurer une qualité de jeu optimale pour tous. À cette fin, une plate-forme de simulation implémentant le modèle proposé a été construite afin d'évaluer le fonctionnement du modèle sous différentes conditions. Plusieurs simulations complètes de longue durée ont été réalisées. À partir des données produites par ces simulations, nous avons étudié la charge consommée par le serveur central par rapport au modèle client-serveur classique. Nous avons également étudié la charge imposée à chaque noeud serveur pour s'assurer que la capacité maximale n'était pas dépassée et que la latence demeurait dans des valeurs raisonnables. Les simulations les plus restrictives au niveau des paramètres ont montré que dans certaines situations limites (un très grand nombre de joueurs sont rassemblées dans une région restreinte, ou alors la capacité des noeuds est trop faible), le modèle peut avoir de la difficulté à maintenir une bonne répartition de charge. À l'inverse, nous avons déterminé que sous des conditions typiques (capacité des noeuds, distribution des joueurs, taille du monde virtuel), le modèle est pleinement fonctionnel et permet d'assurer une qualité de jeu très satisfaisante pour pratiquement l'ensemble des joueurs, et ce, malgré les fluctuations et changements à l'univers virtuel survenant continuellement en cours de jeu. Nous pouvons donc conclure en disant que le modèle proposé constitue une alternative fonctionnelle et efficace au modèle client-serveur actuellement mis en place.----------Abstract In the recent years, the video game industry has been given much attention. More specifically, a new game genre, massive multiplayer online games (MMOG), has emerged. MMOG games feature a very large and persistent virtual universe that always remains active and evolves continuously. Contrary to other traditional multiplayer games, massively multiplayer online games typically have thousands of simultaneous connected players. As for the moment, managing such complex game universes takes a lot of system resources. Furthermore, adapting to the uctuing number of game players is an important challenge. As of today, massively multiplayer online games use the so-called client-server model, but this model is limited by the fact that a single machine cannot handle more than a given number of players. A peer-to-peer model is a more interesting approach since it allows redistributing game maintenance load to all player nodes. Some peer-to-peer approaches propose have been proposed in the litterature. We propose going farther by proposing a exible hybrid architecture that can adapt itself to current game conditions. More precisely, our approach propose dynamically splitting the game territory into a given number of pieces and assigning each \piece" to an arbitrarily-chosen server node from the currently participating players. The proposed model then propose continuously analyzing the network load for each game zone and automatically applying rebalancing operations to redistribute the load, eectively leading to a better game quality for all players, in all conditions. A simulation patform implementing the proposed model has been developped. This platform, called the \simulator", has been built to evaluate our model operates under dierent conditions. Many complete simulations have been performed. Those simulations have been run for a long time lapse. Data samples have then been produced from the performed simulations. We proceeded to study the load consumed by the central server using the proposed model and compared it against the client-server model. We also studied the load imposed to each server node to ensure the maximal allowable load wasn't exceeded and made sure that the latency was within an acceptable range. The simulations with the more restrictive parameters demonstrated that under some critical situations (such as a very large number of players located in a small area or such as a very low node load threshold), the proposed model may have trouble maintaining a good load balancing. Inversely, we have determined that under typical conditions (node load threshold, player distribution, virtual world size), the model is fully functional and ensures an excellent game quality for pratically all players, despite the constantly-evolving nature of MMOG games. Consequently, we can conclude by saying that the proposed model is a functional and ecient alternative to the traditional client-server typically used in today's applications

Economie politique de la LOLF.

La loi organique sur les lois de finances (LOLF), adoptée en 2001, est pleinement mise en application depuis janvier 2006. Cette loi s'inscrit dans un mouvement visant « à substituer un fonctionnement managérial à un fonctionnement juridique » basé sur deux grands principes : l'amélioration de la gestion publique et la transparence. Moins d'un an après la pleine mise en oeuvre de la LOLF et un an après le démarrage des audits de modernisation, ministère par ministère, qui l'accompagnent, ce rapport vise à souligner les enjeux de la réforme budgétaire pour l'État, pour l'organisation administrative et le management public, mais aussi pour l'économie française. Quatre questions sont successivement abordées, avec à l'appui des compléments figurant en annexe de ce rapport et rédigés par différentes personnalités : quels sont les principaux fondements de la réforme budgétaire ? Quelles leçons tirer des expériences menées en la matière à l'étranger ? Quels sont les principaux apports et défis de la LOLF ? Quelles principales recommandations déduire de ce « voyage » dans le nouvel espace budgétaire français ?This report focuses on the principles presiding over the implementation of the LOLF, which, the authors note, is part of a movement towards ‘the substitution of managerial functioning for legal functioning’ based on two major principles: the improvement of public sector management and transparency.LOLF;

ThingsMigrate: Platform-Independent Migration of Stateful JavaScript IoT Applications

The Internet of Things (IoT) has gained wide popularity both in academic and industrial contexts. As IoT devices become increasingly powerful, they can run more and more complex applications written in higher-level languages, such as JavaScript. However, by their nature, IoT devices are subject to resource constraints, which require applications to be dynamically migrated between devices (and the cloud). Further, IoT applications are also becoming more stateful, and hence we need to save their state during migration transparently to the programmer. In this paper, we present ThingsMigrate, a middleware providing VM-independent migration of stateful JavaScript applications across IoT devices. ThingsMigrate captures and reconstructs the internal JavaScript program state by instrumenting application code before run time, without modifying the underlying Virtual Machine (VM), thus providing platform and VM-independence. We evaluated ThingsMigrate against standard benchmarks, and over two IoT platforms and a cloud-like environment. We show that it can successfully migrate even highly CPU-intensive applications, with acceptable overheads (about 30%), and supports multiple migrations

The Effects of Cognitive-Affective Switching With Unpredictable Cues in Adults and Adolescents and Their Relation to “Cool” Executive Functioning and Emotion Regulation

The impact of emotion on executive functioning is gaining interest. It has led to the differentiation of “cool” Executive Functioning (EF) processes, such as cognitive flexibility, and “hot” EF processes, such as affective flexibility. But how does affective flexibility, the ability to switch between cognitive and affective information, vary as a function of age and sex? How does this construct relate to “cool” executive functioning and cognitive-emotion regulation processes? In this study, 266 participants, including 91 adolescents (M = 16.08, SD = 1.42 years old) and 175 adults (M = 25.69, SD = 2.17 years old), completed a cognitive–affective switching task with specific (as opposed to general) unpredictable switches, as well as measures of inhibition, attention, and cognitive-emotion coping strategies. We expected cognitive to affective switching to be more costly than affective to cognitive switching in females versus males, as well as higher switch costs in adolescents. Using linear mixed modelling, we analysed the effect of age, sex, and types of switching on reaction time. Results show that adolescents are slower switchers than adults, and demonstrate that females, although faster switchers than males, are slower when switching from cognitive to affective content than when they are switching from affective to cognitive content. Multiple regression analyses revealed age-specific associations between cognitive-affective switching and inhibition. These results converge with reported developmental and gender specificities in EF and emotion processing, respectively. Additionally, affective flexibility could relate to differences in vigilance and inhibition

TPTO: A Transformer-PPO based Task Offloading Solution for Edge Computing Environments

Emerging applications in healthcare, autonomous vehicles, and wearable assistance require interactive and low-latency data analysis services. Unfortunately, cloud-centric architectures cannot fulfill the low-latency demands of these applications, as user devices are often distant from cloud data centers. Edge computing aims to reduce the latency by enabling processing tasks to be offloaded to resources located at the network's edge. However, determining which tasks must be offloaded to edge servers to reduce the latency of application requests is not trivial, especially if the tasks present dependencies. This paper proposes a DRL approach called TPTO, which leverages Transformer Networks and PPO to offload dependent tasks of IoT applications in edge computing. We consider users with various preferences, where devices can offload computation to an edge server via wireless channels. Performance evaluation results demonstrate that under fat application graphs, TPTO is more effective than state-of-the-art methods, such as Greedy, HEFT, and MRLCO, by reducing latency by 30.24%, 29.61%, and 12.41%, respectively. In addition, TPTO presents a training time approximately 2.5 times faster than an existing DRL approach

MASCIPO – Centre d’études nord-américaines (CENA)

Christophe Apprill, chercheur associé au Centre Norbert-EliasSara Le Menestrel, chargée de recherche au CNRSKali Argyriadis, Julien Mallet, Nicolas Puig, chargés de recherche à l’IRDGuillaume Samson, chargé de mission au Pôle régional des musiques actuelles de La RéunionGabriel Segré, maître de conférences à l’Université Paris-Ouest/Nanterre La Défense Parcours croisés en anthropologie de la musique et de la danse Ce séminaire a porté sur les rapports de domination et les logiques de circulat..