Nordic Electricity Congestion's Arrangement as a Model for Europe: Physical Constraints or Operators' Opportunity

Nordic Electricity Congestion's Arrangement as a Model for Europe: Physical Constraints or Operators' Opportunit

Governance of substance use as a by-product of policing in Norway : a historical account

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Nordic electricity congestion's arrangement as a model for Europe : physical constraints or operators' opportunism?

Congestion on power grids seems a physical reality, a "hard" fact easy to check. Our paper models a different idea: congestion signal may be distorted by transmission system operators (TSOs), which puts the European integrated electricity market at risk. 1ʻ when the TSOs share the revenue produced by congestion's pricing they have an incentive in distorting data. 2ʻ because congestion signals are not physical data but "home made" conventions, TSOs could be able distorting them. 3ʻ when congestion appears on cross border lines that link several countries with their own regulatory mechanisms, the settlement of this incentive's problem necessitates a high degree of coordination. Congestion puts undoubtedly the threat of a collapse on interconnected grids. The "capacity constrained situations" have therefore to be avoided. Congestion signalling depends on norms set by TSOs and a signal is given when the power flows attain the "secure" limits set by TSOs. These security norms are not stable and invariable because some flexibility is needed by the very nature of the power flows and because lines physical capacity limits are not constant. Therefore TSOs are defining the congestion signal on a variable, complex and non transparent constraint and may manipulate it for their own interests. In Nordic countries the "Light Handed Regulation" makes this opportunistic behaviour more likely. We need a more effective congestion regulatory mechanism.Supported by the MIT Center for Energy and Environmental Policy Research

Simulations expérimentale et numérique de réfractaires verriers électrofondus riches en zircone

International audienceLes réfractaires électrofondus à Très Haute Teneur en Zircone sont utilisés dans la construction des fours verriers. Le fond de la zone fusion est constitué de dalles de THTZ (88%vol ZrO2, 12%vol phase vitreuse), matériau choisi pour sa faible conductivité thermique, sa forte réfractarité et son inertie chimique. Le THTZ est élaboré par électrofusion, coulé dans des moules puis refroidi de manière contrôlée jusqu'à température ambiante, domaine où le matériau se caractérise par un comportement fragile. Lors de la première mise en chauffe du four ("attrempage"), des contraintes internes d'origine thermique sont générées au sein des dalles. L'objectif de l'étude est alors d'estimer ce champ de contraintes. L'étude a tout d'abord consisté à simuler expérimentalement la chauffe d'une dalle de THTZ dans un four verrier pendant l'attrempage. Pour ce faire, nous avons développé et utilisé un dispositif expérimental consistant à poser une dalle de THTZ instrumentée en thermocouples sur une plaque chauffée à une vitesse contrôlée. Les données thermiques ainsi obtenues ont permis, via un calcul numérique thermique (code de calcul ZéBuLoN, Centre des Matériaux), de déterminer les coefficients d'échange aux interfaces dalle/air et dalle/plaque chauffante. Puis, à partir de cela, un calcul numérique mécanique nous a permis de déterminer les contraintes générées par l'attrempage dans la dalle

Transgenesis and humanization of murine antibodies.

International audienceThe properties of monoclonal antibodies explain why they are such a successful class of therapeutic molecules. However, pionneered initial antibodies were of murine origin and triggered an immune response which limited the therapeutic potential of the antibody and generated deleterious effects. Consequently, tremendous efforts have been developped to engineer these murine Ig by introducing human sequences in vitro, or in vivo by humanization of murine antibodies, leading to chimeric immunoglobulins, and more recently generation of fully human antibodies in transgenic mice with a more or less diversified V repertoire. These approaches have led to the development of an increasing number of these chimeric or humanized monoclonal antibodies entering pharmaceutical pipelines. double dagger

Arcing on Solar Generators by Collection of Ionospheric Plasma Currents

International audienceThere are several well-known possibilities to trigger a secondary arc on solar arrays by creation of conductive plasma produced in the gap between two solar cell strings. It could be by electrostatic discharges due to an inverse potential gradient condition, micrometeoroid impacts or laser impacts. The development of electrical propulsion for satellites requires higher voltages on solar arrays. These voltages strongly modify the plasma-satellite interactions, especially by increasing the collection of plasma currents. By studying this plasma collection current on solar cell samples, we have detected secondary arcs between two strings without any triggering event as previously described. Focusing on this event, we found that a series of physical phenomena may lead to secondary arcing situation: heating by plasma current collection, outgassing, Paschen discharge conditions and then secondary arcing. We have reproduced on solar cell like samples what occurs when an arc starts and the conditions for its occurrence. Thereby, we have defined when this phenomenon is able to happen on real solar arrays

Myrtilles et mémoire : les myrtilles protègent-elles des pertes de mémoire liées à l’âge ? Etude bibliographique

Cette étude bibliographique décrit brièvement les fonctions cognitives ainsi que les différents types de mémoire. Puis elle expose les effets du vieillissement et des aliments sur les mémoires. Enfin, les travaux sur les effets des myrtilles sur la mémoire, ainsi que leurs mécanismes moléculaires sont regroupés et analysés, chez les rongeurs et chez l’homme. Cette synthèse montre que certains aliments, les myrtilles notamment, ont des effets nets sur la mémoire spatiale des vieux rats. La poursuite des études expérimentales est nécessaire car les pertes de mémoires liées à l’âge sont un fléau pour la population vieillissante. Il serait donc opportun de valider ces études par un essai clinique randomisé de grande ampleur de l’effet des myrtilles sur la mémoire des personnes âgées

Selection on the wing in Heliconius butterflies

<p>Asbtract</p> <p>To what extent population structure favours the establishment of new phenotypes within a species remains a fundamental question in evolutionary studies. By reducing gene flow, habitat fragmentation is a major factor shaping the genetic structuring of populations, favouring isolation of small populations in which drift may rapidly change frequencies of new variants. When these variants provide advantages to individuals, the combined effect of selection and drift can lead to rapid shifts in phenotypes. In a study published in <it>BMC Genetics</it>, Albuquerque de Moura <it>et al. </it>asked whether such a general pattern of population structure can be observed in <it>Heliconius </it>species, which could have strong implication in the evolution of colour pattern diversification in these butterflies. In this commentary we discuss the potential roles of these three processes (drift, selection and dispersal) on the evolution of <it>Heliconius </it>wing patterns in regard to the findings of a common fine-scale population structure within the co-mimetic species <it>H. melpomene </it>and <it>H. erato</it>. Indeed, a general pattern of population subdivision in the history of these two species may have provoked the major phenotypical shifts observed in their wing colour patterns. The suggestion that coupled environmental pressures (counter-selection of dispersal and selection on co-evolved traits) could be responsible for identical genetic differentiation profiles in <it>H. erato </it>and <it>H. melpomene </it>clearly merits further investigations using both detailed population genetic (including landscape genetic) and ecological studies.</p