Méthodologie d'évaluation énergétique des quartiers périurbains. Perspectives pour le renouvellement périurbain wallon.

Doctoral thesis (2013)

The process of urban sprawl, which commonly describes physically expanding urban areas, is a major issue for sustainable development. Urban sprawl is known to represent a significant contribution to the ... [more ▼]

The process of urban sprawl, which commonly describes physically expanding urban areas, is a major issue for sustainable development. Urban sprawl is known to represent a significant contribution to the overall energy consumption of a territory for energy needs in buildings and for transportation. In this context, the thesis focuses on the energy assessment of existing suburban neighborhoods. The assessment includes two parts: (1) a computational approach combining dynamic simulation tools and a database of building typologies to determine the energy consumed in heating and (2) an empirical approach to assess the energy consumed by transportation systems (home-to-work and home-to-school journeys). The links between the spatial structure of the territory and energy use for commuting are highlighted. Several renewal strategies are proposed to improve energy efficiency in existing suburban neighborhoods. There investigate the thermal retrofitting of existing neighborhoods, the built density and demolition/reconstruction processes together with the location of the neighborhoods. Urban structure acts upon travel energy consumption for commuting. A good mix between work, schools and dwellings at the local scale, which allows reduced travel distances, is a good strategy to reduce transport energy consumption, whereas means of transport used is only of little impact. Student travel behaviors are specific to the level of education and the type of neighborhood. Finally, the thesis discusses the practical implications of the research to operationalize a suburban renewal that articulates energy efficiency of buildings and neighborhoods but also energy efficiency of the urban structure. [less ▲]

Présentation de la théorie du cinéma d'Alexander Kluge : Kluge, Adorno, Bloch

Scientific conference (2013, January 12)

Learning to Predict End-to-End Network Performance

Doctoral thesis (2013)

The knowledge of end-to-end network performance is essential to many Internet applications and systems including traffic engineering, content distribution networks, overlay routing, application-level ... [more ▼]

The knowledge of end-to-end network performance is essential to many Internet applications and systems including traffic engineering, content distribution networks, overlay routing, application-level multicast, and peer-to-peer applications. On the one hand, such knowledge allows service providers to adjust their services according to the dynamic network conditions. On the other hand, as many systems are flexible in choosing their communication paths and targets, knowing network performance enables to optimize services by e.g. intelligent path selection. In the networking field, end-to-end network performance refers to some property of a network path measured by various metrics such as round-trip time (RTT), available bandwidth (ABW) and packet loss rate (PLR). While much progress has been made in network measurement, a main challenge in the acquisition of network performance on large-scale networks is the quadratical growth of the measurement overheads with respect to the number of network nodes, which renders the active probing of all paths infeasible. Thus, a natural idea is to measure a small set of paths and then predict the others where there are no direct measurements. This understanding has motivated numerous research on approaches to network performance prediction. Commonly, the success of a prediction system is built on its scalability, efficiency, accuracy and practicability. For network performance prediction, two specific requirements have to be met. First, the prediction system should have a decentralized architecture which allows the natural deployment of the system within a networked application. Second, as different performance metrics are useful for different applications, the prediction system should be general and flexible to deal with various metrics in a unified framework. This thesis presents practical approaches to network performance prediction. There are three main contributions. First, the problem of network performance prediction is formulated as a matrix completion problem where the matrix contains performance measures between network nodes with some of them known and the others unknown and thus to be filled. This new formulation is advantageous in that it is flexible to deal with various metrics in a unified framework, despite their diverse nature. The only requirement is that the matrix to be completed has a low-rank characteristic, which has long been observed in performance matrices constructed from various networks and in various metrics. Second, the matrix completion problem is solved by a novel approach called Decentralized Matrix Factorization by Stochastic Gradient Descent (DMFSGD). The approach requires neither explicit constructions of matrices nor special nodes such as landmarks and central servers. Instead, by letting network nodes exchange messages with each other, matrix factorization is collaboratively and iteratively achieved at all nodes, with each node equally retrieving a number of measurements. The approach is practical in that it is simple, with no infrastructure, and is computationally lightweight, containing only vector operations. Third, instead of the conventional representation of exact metric values, this thesis also investigates coarse performance representations including binary classes (The performance is classified into binary classes of either ``good'' or ``bad''.) and ordinal ratings (The performance is quantized from 1 star to 5 stars.). Such more qualitative than quantitative measures not only fulfill the requirements of many Internet applications, but also reduce the measurement cost and enable a unified treatment of various metrics. In addition, as both class and rating measures can be nicely integrated in the matrix completion framework, the same DMFSGD approach is applicable for their prediction, with little modification required. The resulting prediction system has been extensively evaluated on various publicly-available datasets of two kinds of metrics, namely RTT and ABW. These experiments demonstrate not only the scalability and the accuracy of the DMFSGD approach but also its usability in real Internet applications. In addition, the benefits of predicting performance classes and ratings, rather than their actual values, are demonstrated by a case study on peer selection, a function that is commonly required in a number of network applications. [less ▲]

L'espace théorique du langage. Des parallèles foues

Book published by Academia (2013)

La question de la fonction du langage dans l’ensemble des activités humaines continue de susciter abondance de discours qui tendent tous à en faire la théorie. Autant de « recherches parallèles », disait ... [more ▼]

La question de la fonction du langage dans l’ensemble des activités humaines continue de susciter abondance de discours qui tendent tous à en faire la théorie. Autant de « recherches parallèles », disait Benveniste, parlant des « sciences voisines » de la linguistique qui était alors en plein essor. Malgré ce terme qui semblait les vouer à rester indépendantes dans leur démarche et leur visée, en quelque sorte réduites à s’aligner, sans espoir de contact, sur la linguistique elle-même, Benveniste n’hésitait pas à leur donner un horizon commun : « Ces recherches parallèles […] concourent à une véritable science de la culture qui fondera les théories des activités symboliques de l’homme ». Les textes réunis ici sont tous issus d’un groupe de travail fondé dans les années 1970. Au départ Groupe de Recherche en Histoire de la Linguistique (GRHIL), il s’est élargi à des horizons divers à des philosophes, des sémioticiens, des psychanalystes. Ce volume en restitue l’intensité des échanges et des réflexions, et devrait donner quelque unité à ces points de vue différents. Une façon de justifier son titre, étrange mais évocateur, qui dit la fascination et la difficulté que suscitent ces discours pluriels sur le langage [less ▲]

Tolkien et la "high fantasy"

Article for general public (2013)

Dossier d'actualité : la défédéralisation des allocations familiales - Interview de Christian Behrendt

Article for general public (2013)

RELEVANCE OF A SYSTEMATIC GERIATRIC SCREENING AND ASSESSMENT IN OLDER PATIENTS WITH CANCER RESULTS OF A PROSPECTIVE MULTICENTRIC STUDY

in Annals of Oncology (2013)

Neuroestrogens Rapidly Regulate Sexual Motivation But Not Performance

in Journal of Neuroscience (2013), 33(1), 164-174

Estrogens exert pleiotropic effects on reproductive traits, which include differentiation and activation of reproductive behaviors and the control of the secretion of gonadotropins. Estrogens also ... [more ▼]

Estrogens exert pleiotropic effects on reproductive traits, which include differentiation and activation of reproductive behaviors and the control of the secretion of gonadotropins. Estrogens also profoundly affect non-reproductive traits, such as cognition and neuroprotection. These effects are usually attributed to nuclear receptor binding and subsequent regulation of target gene transcription. Estrogens also affect neuronal activity and cell-signaling pathways via faster, membrane-initiated events. How these two types of actions that operate in distinct timescales interact in the control of complex behavioral responses is poorly understood. Here, we show that the central administration of estradiol rapidly increases the expression of sexual motivation, as assessed by several measures of sexual motivation produced in response to the visual presentation of a female but not sexual performance in male Japanese quail. This effect is mimicked by membrane-impermeable analogs of estradiol, indicating that it is initiated at the cell membrane. Conversely, blocking the action of estrogens or their synthesis by a single intracerebroventricular injection of estrogen receptor antagonists or aromatase inhibitors, respectively, decreases sexual motivation within minutes without affecting performance. The same steroid has thus evolved complementary mechanisms to regulate different behavioral components (motivation vs performance) in distinct temporal domains (long- vs short-term) so that diverse reproductive activities can be properly coordinated to improve reproductive fitness. Given the pleiotropic effects exerted by estrogens, other responses controlled by these steroids might also depend on a slow genomic regulation of neuronal plasticity underlying behavioral activation and an acute control of motivation to engage in behavior. [less ▲]

The Newly Discovered Pulsating Low Mass White Dwarfs: An Extension of the ZZ Ceti Instability Strip

in Astrophysical Journal (2013), 762

In light of the exciting discovery of g-mode pulsations in extremely low-mass, He-core DA white dwarfs, we report on the results of a detailed stability survey aimed at explaining the existence of these ... [more ▼]

In light of the exciting discovery of g-mode pulsations in extremely low-mass, He-core DA white dwarfs, we report on the results of a detailed stability survey aimed at explaining the existence of these new pulsators as well as their location in the spectroscopic Hertzsprung–Russell diagram. To this aim, we calculated some 28 evolutionary sequences of DA models with various masses and chemical layering. These models are characterized by the so-called ML2/α = 1.0 convective efficiency and take into account the important feedback effect of convection on the atmospheric structure. We pulsated the models with the nonadiabatic code MAD, which incorporates a detailed treatment of time-dependent convection. On the other hand, given the failure of all nonadiabatic codes, including MAD, to account properly for the red edge of the strip, we resurrect the idea that the red edge is due to energy leakage through the atmosphere. We thus estimated the location of that edge by requiring that the thermal timescale in the driving region—located at the base of the H convection zone—be equal to the critical period beyond which l = 1 g-modes cease to exist. Using this approach, we find that our theoretical ZZ Ceti instability strip accounts remarkably well for the boundaries of the empirical strip, including the low-gravity, low-temperature regime where the three new pulsators are found. We also account for the relatively long periods observed in these stars, and thus conclude that they are true ZZ Ceti stars, but with low masses. [less ▲]

New INTEGRAL Observations of η Carinae Close to Periastron

in Astronomical Society of the Pacific Conference Series (2013, January 01)

The soft X-ray thermal emission of η Carinae varies strongly around the periastron, following the orbital period of 5.5 yr. We studied the hard X-ray non-thermal emission of η Car using new INTEGRAL ... [more ▼]

The soft X-ray thermal emission of η Carinae varies strongly around the periastron, following the orbital period of 5.5 yr. We studied the hard X-ray non-thermal emission of η Car using new INTEGRAL observations taken close to periastron. We showed that the hard X-ray emission is very likely to be associated with η Car, and not with any other source found within the INTEGRAL error circle. We also showed that the 3-σ detection during the soft X-ray minimum is consistent with a hydrogen column density that does not exceed 6×10[SUP]23[/SUP] cm[SUP]-2[/SUP]. [less ▲]