Investigation of evaporation and condensation processes specific to grooved flat heat pipes

International audienceTemperature and liquid-vapor interface measurements obtained with a flat plate heat pipe (FPHP) in various experimental conditions are presented. The grooved FPHP is made of copper. The results are compared to a thermal model, developed in a previous work, in which heat conduction in the FPHP wall as well as evaporation and condensation heat transfer phenomena are taken into account. The model depends on the shape of the liquid-vapor interface in the grooves and on the fins at the condenser. A good agreement is found between the evaporation model and the experimental data. However the results of the condensation model overestimate the heat transfer coefficient, due to a bad estimation of the condensate film on the fins. Experimental measurements obtained with a second FPHP made of silicon are used to analyze the shape of this film. For both evaporation and condensation models, the results show a strong influence of the accommodation coefficient

Paris, métropoles. Le défi de la gouvernance

Les Mini-Métropolitaines, lancées il y a plus de deux ans par le Secrétariat Général de la Ville de Paris et par Pierre Mansat, l’Adjoint au Maire de Paris en charge de Paris Métropole et des relations avec les collectivités d’Île-de-France, rencontrent un succès croissant. Chaque mois, pour une conférence-débat d’une heure et demie, un expert ou un chercheur vient à la rencontre d’un public de plus en plus divers : cadres territoriaux, enseignants et chercheurs, membres d’associations, acteurs de terrain ou citoyens intéressés par les questions métropolitaines. Il s’agit non seulement de comprendre la métropole parisienne, mais aussi de se familiariser avec les enjeux liés au phénomène de métropolisation à l’oeuvre partout dans le monde. Il est question de Paris mais aussi des autres grandes métropoles mondiales, qu’elles se situent dans les pays industrialisés, émergents ou en voie de développement. Et, dans le même esprit d’ouverture, les Mini-Métropolitaines ont choisi de croiser toutes les disciplines : sociologie, histoire, géographie, urbanisme… Ce numéro 2 des Cahiers rend compte des différentes interventions qui ont rythmé l’année 2011-2012. Au menu : une explication de la gouvernance du Grand Londres (Christian Lefèvre), un point sur l’histoire de l’approvisionnement parisien des Halles à Rungis (Guy Chemla), un bilan sur la fin de la sectorisation scolaire (Marco Oberti), une évocation du rap et de la notion de territoire (Olivier Cachin), un focus sur quinze ans d’expérience de démocratie participative (Philippe Subra), un aperçu de “l’émiettement de la métropole” en de multiples communes périurbaines (éric Charmes), une mise au point sur la biodiversité en ville et sa prise en considération dans les politiques d’aménagement (Philippe Clergeau) et un entretien croisé au sujet de la voiture en ville (Bruno Marzloff et Mathieu Flonneau). Diversité des thèmes abordés, variété des compétences : les Mini-Métropolitaines décryptent la complexité des phénomènes urbains et les enjeux majeurs auxquels doivent faire face les grandes villes du monde avec un regard particulièrement attentif porté sur la métropole parisienne. (Présentation

Quels pouvoirs pour les territoires métropolitains ?

À l’occasion du récent colloque « Gouverner les métropoles », les auteurs reviennent sur les relations entre pouvoirs et territoires dans les grandes métropoles. Entre l’évolution du rôle de l’État, l’indétermination des périmètres d’intervention, la difficile constitution des espaces politiques à ces échelles et l’importance de l’informel, les métropoles obligent à reconfigurer les jeux d’acteurs historiques

Formulation of a 4-DoF torsion/bending element for the formfinding of elastic gridshells

International audienceThe paper presents a completely novel approach to model elastic gridshells with a 4-DoF element based on recent advances in the field of hair modelling [1]. This element, based on Kirchhoff's beam theory, can account for both bending and torsion behaviours. The reduction from 6 to 4 degrees of freedom is achieved with an appropriate curve framing introduce by R. Bishop [2]. The resulting model is fast and efficient. Its accuracy has been validated on test cases. It opens new outlooks for the design of elastic gridshells

Hybrid Input-Output tables for CGE model calibration and consequences on energy policy analysis

International audienceHybrid modelling approaches are increasingly used to bridge the historical gap between the bottom-up (BU) and top-down (TD) approaches to energy/economy/environment (E3) modelling. By nature, they require a substantial effort of harmonisation between national accounts and energy balance data. For most computable general equilibrium (CGE) models defined at the scale of a given country, efforts have been made to reconcile those data. But the methods being used and their impacts on the empirical information are generally poorly documented. Models domains corresponding to multiple countries rely on hybrid datasets whose characteristics and methods of production are not explored in details. Such an exploration is required, however, because different hybridisation techniques have different impacts on key empirical features that are important for policy evaluation. After reviewing the literature on hybridisation methods, this paper proposes an innovative procedure for building hybrid Input-Output matrices at the scale of a country, and illustrates it with data for France. Compared to existing methods, this procedure includes information about energy flows, prices and quantities coming from energy statistics, without alteration on this data. All this information is then introduce within a consistent social accounting framework. The impact of this method is illustrated in a standard Capital-Labour-Energy (‘KLEM’) CGE model. The welfare costs of the same price-induced energy policy are evaluated, keeping the same behavioural structural assumptions and parameters. The model is alternatively calibrated either using our hybrid matrices or unmodified original input-output data from national accounts. This comparison shows that the model calibrated on hybridised data produce systematically lower welfare costs estimates, when targeting energy reduction alternatively on firm consumptions and household consumptions

Decrease in ovalbumin-induced pulmonary allergic response by benzaldehyde but not acetaldehyde exposure in a guinea pig model

International audienceThe pulmonary effects of two environmentally relevant aldehydes were investigated in non-sensitized or ovalbumin (OA)-sensitized guinea pigs (GPs). Four-week-old male Hartley GPs, weighing about 400 g, were intraperitoneally injected with 1 ml of an NaCl solution containing 100 mug OA and 100 mg Al/(OH)(3). They were then exposed to either acetaldehyde (200 ppb) or benzaldehyde (500 ppb) (or 4 wk (6 h/d, 5 d/wk). At the end of exposure, GPs were challenged with an OA aerosol (0.1% in NaCl) and pulmonary functions were measured. The day after, guinea pigs were anesthetized and several endpoints related to inflammatory anti allergic responses were assessed in blood, whole-lung histology, and bronchoalveolar lavage (BAL). Sensitized nonexposed GPs showed bronchial hyperresponsiveness to OA and an increased number of eosinophils in blood and BAL, together with a rise in total protein and leukotrienes (LTB4 and LTC4/D-4/E-4) in BAL. In nonsensitized GPs, exposure to acetaldehyde or benzaldehyde did not induce any change in the tested parameters;, with the exception of irritation of the respiratory tract as detected by histology and an increased number of alveolar macrophages in animals exposed to acetaldehyde. In sensitized GPs, exposure to acetaldehyde induced a moderate irritation of the respiratory tract but no change in biological parameters linked to the inflammatory and allergic responses, In contrast, exposure to benzaldehyde induced a decrease both in OA-induced bronchoconstriction and in eosinophil and neutrophil numbers in BAL, an increase in the bronchodilatator mediator prostaglandin E-2 (PGE(2)) and a decrease in the bronchoconstrictor mediators LTC4/D-4/E-4. Further investigations are needed to determine if the attenuated response observed in sensitized GPs exposed to benzaldehyde is due to an alteration of the mechanism of sensitization or to a more direct effect on various mechanisms of the allergic response

Clinical and Economic Impact of Adopting Noninvasive Prenatal Testing as a Primary Screening Method for Fetal Aneuploidies in the General Pregnancy Population.

peer reviewed[en] OBJECTIVE: To evaluate the clinical and economic impact of adopting noninvasive prenatal testing (NIPT) using circulating cell-free DNA as a first-line screening method for trisomy 21, 18, and 13 in the general pregnancy population. METHODS: A decision-analytical model was developed to assess the impact of adopting NIPT as a primary screening test compared to conventional screening methods. The model takes the Belgium perspective and includes only the direct medical cost of screening, diagnosis, and procedure-related complications. NIPT costs are EUR 260. Clinical outcomes and the cost per trisomy detected were assessed. Sensitivity analysis measured the impact of NIPT false-positive rate (FPR) on modelled results. RESULTS: The cost per trisomy detected was EUR 63,016 for conventional screening versus EUR 66,633 for NIPT, with a difference of EUR 3,617. NIPT reduced unnecessary invasive tests by 94.8%, decreased procedure-related miscarriages by 90.8%, and increased trisomies detected by 29.1%. Increasing the FPR of NIPT (from < 0.01 to 1.0%) increased the average number of invasive procedures required to diagnose a trisomy from 2.2 to 4.5, respectively. CONCLUSION: NIPT first-line screening at a reasonable cost is cost-effective and provides better clinical outcomes. However, modelled results are dependent on the adoption of an NIPT with a low FPR

An assessment of the Atlantic and Arctic sea–air CO2 fluxes, 1990–2009

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 10 (2013): 607-627, doi:10.5194/bg-10-607-2013.The Atlantic and Arctic Oceans are critical components of the global carbon cycle. Here we quantify the net sea–air CO2 flux, for the first time, across different methodologies for consistent time and space scales for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea–air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from global observations and modeling products, specifically a pCO2-based CO2 flux climatology, flux estimates from the inversion of oceanic and atmospheric data, and results from six ocean biogeochemical models. Additionally, we use basin-wide flux estimates from surface ocean pCO2 observations based on two distinct methodologies. Our estimate of the contemporary sea–air flux of CO2 (sum of anthropogenic and natural components) by the Atlantic between 40° S and 79° N is −0.49 ± 0.05 Pg C yr−1, and by the Arctic it is −0.12 ± 0.06 Pg C yr−1, leading to a combined sea–air flux of −0.61 ± 0.06 Pg C yr−1 for the two decades (negative reflects ocean uptake). We do find broad agreement amongst methodologies with respect to the seasonal cycle in the subtropics of both hemispheres, but not elsewhere. Agreement with respect to detailed signals of interannual variability is poor, and correlations to the North Atlantic Oscillation are weaker in the North Atlantic and Arctic than in the equatorial region and southern subtropics. Linear trends for 1995 to 2009 indicate increased uptake and generally correspond between methodologies in the North Atlantic, but there is disagreement amongst methodologies in the equatorial region and southern subtropics.U. Schuster has been supported by EU grants IP 511176-2 (CARBOOCEAN), 212196 (COCOS), and 264879 (CARBOCHANGE), and UK NERC grant NE/H017046/1 (UKOARP). G. A. McKinley and A. Fay thank NASA for support (NNX08AR68G, NNX11AF53G). P. Landsch¨utzer has been supported by EU grant 238366 (GREENCYCLESII). N. Metzl acknowledges the French national funding program LEFE/INSU. Support for N. Gruber has been provided by EU grants 264879 (CARBOCHANGE) and 283080 (GEO-CARBON) S. Doney acknowledges support from NOAA (NOAA-NA07OAR4310098). T. Takahashi is supported by NOAA (NAO80AR4320754)

Plant-mediated effects on mosquito capacity to transmit human malaria

The ecological context in which mosquitoes and malaria parasites interact has received little attention, compared to the genetic and molecular aspects of malaria transmission. Plant nectar and fruits are important for the nutritional ecology of malaria vectors, but how the natural diversity of plant-derived sugar sources affects mosquito competence for malaria parasites is unclear. To test this, we infected Anopheles coluzzi, an important African malaria vector, with sympatric field isolates of Plasmodium falciparum, using direct membrane feeding assays. Through a series of experiments, we then examined the effects of sugar meals from Thevetia neriifolia and Barleria lupilina cuttings that included flowers, and fruit from Lannea microcarpa and Mangifera indica on parasite and mosquito traits that are key for determining the intensity of malaria transmission. We found that the source of plant sugar meal differentially affected infection prevalence and intensity, the development duration of the parasites, as well as the survival and fecundity of the vector. These effects are likely the result of complex interactions between toxic secondary metabolites and the nutritional quality of the plant sugar source, as well as of host resource availability and parasite growth. Using an epidemiological model, we show that plant sugar source can be a significant driver of malaria transmission dynamics, with some plant species exhibiting either transmission-reducing or -enhancing activities