On distributed virtual network embedding with guarantees

To provide wide-area network services, resources from different infrastructure providers are needed. Leveraging the consensus-based resource allocation literature, we propose a general distributed auction mechanism for the (NP-hard) virtual network (VNET) embedding problem. Under reasonable assumptions on the bidding scheme, the proposed mechanism is proven to converge, and it is shown that the solutions guarantee a worst case efficiency of (?????) relative to the optimal solution, and that this bound is optimal, that is, no better approximation exists. Using extensive simulations, we confirm superior convergence properties and resource utilization when compared with existing distributed VNET embedding solutions, and we show how byappropriate policy design, our mechanism can be instantiated to accommodate the embedding goals of different service and infrastructure providers, resulting in an attractive and flexible resource allocation solution.This work is supported in part by the National Science Foundation under grant CNS-0963974

On distributed virtual network embedding with guarantees

To provide wide-area network services, resources from different infrastructure providers are needed. Leveraging the consensus-based resource allocation literature, we propose a general distributed auction mechanism for the (NP-hard) virtual network (VNET) embedding problem. Under reasonable assumptions on the bidding scheme, the proposed mechanism is proven to converge, and it is shown that the solutions guarantee a worst case efficiency of (?????) relative to the optimal solution, and that this bound is optimal, that is, no better approximation exists. Using extensive simulations, we confirm superior convergence properties and resource utilization when compared with existing distributed VNET embedding solutions, and we show how byappropriate policy design, our mechanism can be instantiated to accommodate the embedding goals of different service and infrastructure providers, resulting in an attractive and flexible resource allocation solution.This work is supported in part by the National Science Foundation under grant CNS-0963974

On distributed virtual network embedding with guarantees

To provide wide-area network services, resources from different infrastructure providers are needed. Leveraging the consensus-based resource allocation literature, we propose a general distributed auction mechanism for the (NP-hard) virtual network (VNET) embedding problem. Under reasonable assumptions on the bidding scheme, the proposed mechanism is proven to converge, and it is shown that the solutions guarantee a worst-case efficiency of (1-(1/e)) relative to the optimal node embedding, or VNET embedding if virtual links are mapped to exactly one physical link. This bound is optimal, that is, no better polynomial-time approximation algorithm exists, unless P=NP. Using extensive simulations, we confirm superior convergence properties and resource utilization when compared to existing distributed VNET embedding solutions, and we show how by appropriate policy design, our mechanism can be instantiated to accommodate the embedding goals of different service and infrastructure providers, resulting in an attractive and flexible resource allocation solution.CNS-0963974 - National Science Foundationhttp://www.cs.bu.edu/fac/matta/Papers/ToN-CAD.pdfAccepted manuscrip

Les concours généraux de l’enseignement officiel en Belgique (1840-1850). Histoire d’un instrument polyvalent de politique éducative

Créés en 1840 dans l’objectif d’évaluer le niveau des études dans les établissements secondaires de l’État, les concours généraux ont joué un rôle important dans le développement de l’enseignement secondaire en Belgique, durant les premières décennies de l’histoire du pays. Outil de contrôle des performances des établissements secondaires qui recevaient des subsides de l’État, le concours général fournissait de surcroît un cadre de fonctionnement commun aux différentes institutions, tout en stimulant l’émulation et la concurrence entre les étudiants et les professeurs. Par ailleurs, il produisait de nombreuses données quantitatives, qui étaient largement diffusées. L’histoire de son fonctionnement montre qu’il a été utilisé comme un véritable instrument polyvalent de politique éducativeCreated in 1840 with the objective of assessing teaching standards in secondary public schools, the “concours généraux” (open competitions) played an important role in the development of secondary education in Belgium during the first decades of the country’s history. As a tool for monitoring the performance of State-funded secondary schools, the open competition provided the various educational institutions with a common operating framework, while fostering healthy competition between students and teachers. In addition, it produced a wealth of quantitative data which were widely disseminated. The history of how it was run shows that it was used as a truly multipurpose instrument of educational policy

« Prendre exemple du modèle scolaire allemand ? » La réforme des humanités en Belgique à la fin du XIXe siècle dans son contexte européen (1870-1890)

À partir de l’exemple de la réforme de l’enseignement secondaire entreprise par le gouvernement belge dans les années 1880, cet article a l’ambition d’illustrer la façon dont les systèmes scolaires modernes d’Europe occidentale se sont construits sur la base d’un travail de comparaison entre modèles, dans un contexte de circulation internationale des informations et des savoirs. L’article est divisé en trois parties. La première analyse l’origine de la querelle des humanités en la replaçant dans son contexte européen, en rappelant les raisons qui poussaient les différents pays européens à aller chercher ailleurs des modèles à imiter. À travers l’étude de quelques exemples précis, elle montre plus particulièrement pourquoi plusieurs pays se sont intéressés à la réforme belge de 1881 et identifie les raisons de cette dernière. S’appuyant sur l’analyse des débats qui se sont tenus à propos des humanités en Belgique, la seconde et la troisième parties étudient la manière dont les réformateurs belges se sont tournés vers des modèles scolaires étrangers, en premier lieu le modèle allemand. Elles identifient les moyens et canaux de diffusion par lesquels l’information a circulé, examinent les arguments invoqués en faveur de ce modèle pédagogique et montrent les limites rencontrées par son transfert sur le sol national.Taking the reform of secondary education undertaken by the Belgian government in the 1880s as an example, this article aims to show how modern school systems in Western Europe have been based on comparison between models in a context of the international dissemination of information and knowledge. The article is divided into three parts. The first analyses the origin of the “humanities debate” by placing it in its European context, reiterating the reasons that led different European countries to look elsewhere for models. In particular, through the study of a few specific examples, it shows why several countries took an interest in the Belgian reform of 1881 and identifies the reasons for this. Based on an analysis of debate on the subject of the humanities in Belgium, the second and third sections examine the way in which Belgian reformers turned to foreign school models, particularly the German model. They identify the means and channels through which information was disseminated, examine the arguments put forward in favour of this educational model and show the limitations which had to be overcome in transferring it to Belgium

Synthesis, Production, and Biotechnological Applications of Exopolysaccharides and Polyhydroxyalkanoates by Archaea

Extreme environments, generally characterized by atypical temperatures, pH, pressure, salinity, toxicity, and radiation levels, are inhabited by various microorganisms specifically adapted to these particular conditions, called extremophiles. Among these, the microorganisms belonging to the Archaea domain are of significant biotechnological importance as their biopolymers possess unique properties that offer insights into their biology and evolution. Particular attention has been devoted to two main types of biopolymers produced by such peculiar microorganisms, that is, the extracellular polysaccharides (EPSs), considered as a protection against desiccation and predation, and the endocellular polyhydroxyalkanoates (PHAs) that provide an internal reserve of carbon and energy. Here, we report the composition, biosynthesis, and production of EPSs and PHAs by different archaeal species

Humanités et citoyenneté : l’enseignement des lettres et des langues en France, en Suisse et en Belgique au XIXe siècle

Dans un article intitulé « Les humanités au péril d’un monde numérique » paru dans les pages du journal Le Figaro, l’historien et académicien Marc Fumaroli, s’employant à défendre l’utilité et la place des langues classiques dans l’enseignement secondaire en France, rappelle que celles-ci permettent « le développement durable et profond de ce qui fait notre humanité : la liberté intérieure ». Cette intervention s’inscrit dans le cadre d’une controverse sur la fonction et l’avenir de ces disci..

Recent Advances in the Study of Marine Microbial Biofilm: From the Involvement of Quorum Sensing in Its Production up to Biotechnological Application of the Polysaccharide Fractions

The present review will explore the most relevant findings on marine microbial biofilm, with particular attention towards its polysaccharide fraction, namely exopolysaccharide (EPS). EPSs of microbial origin are ubiquitous in nature, possess unique properties and can be isolated from the bacteria living in a variety of habitats, including fresh water or marine environments, extreme environments or different soil ecosystems. These biopolymers have many application in the field of biotechnology. Several studies showed that the biofilm formation is closely related to quorum sensing (QS) systems, which is a mechanism relying on the production of small molecules defined as "autoinducers" that bacteria release in the surrounding environment where they accumulate. In this review, the involvement of microbial chemical communication, by QS mechanism, in the formation of marine biofilm will also be discussed