2,455 research outputs found

    Observing transiting planets with JWST -- Prime targets and their synthetic spectral observations

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    The James Webb Space Telescope will enable astronomers to obtain exoplanet spectra of unprecedented precision. Especially the MIRI instrument may shed light on the nature of the cloud particles obscuring planetary transmission spectra in the optical and near-infrared. We provide self-consistent atmospheric models and synthetic JWST observations for prime exoplanet targets in order to identify spectral regions of interest and estimate the number of transits needed to distinguish between model setups. We select targets which span a wide range in planetary temperature and surface gravity, ranging from super-Earths to giant planets, and have a high expected SNR. For all targets we vary the enrichment, C/O ratio, presence of optical absorbers (TiO/VO) and cloud treatment. We calculate atmospheric structures and emission and transmission spectra for all targets and use a radiometric model to obtain simulated observations. We analyze JWST's ability to distinguish between various scenarios. We find that in very cloudy planets such as GJ 1214b less than 10 transits with NIRSpec may be enough to reveal molecular features. Further, the presence of small silicate grains in atmospheres of hot Jupiters may be detectable with a single JWST MIRI transit. For a more detailed characterization of such particles less than 10 transits are necessary. Finally, we find that some of the hottest hot Jupiters are well fitted by models which neglect the redistribution of the insolation and harbor inversions, and that 1-4 eclipse measurements with NIRSpec are needed to distinguish between the inversion models. Wet thus demonstrate the capabilities of JWST for solving some of the most intriguing puzzles in current exoplanet atmospheric research. Further, by publishing all models calculated for this study we enable the community to carry out similar or retrieval analyses for all planets included in our target list.Comment: 24 pages, 7 figures, accepted for publication in A&

    ModĂ©lisation environnementale rĂ©gionalisĂ©e Ă  l’échelle mondiale de l’acidification terrestre et aquatique dans le cadre de l’évaluation des impacts du cycle de vie

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    L’acidification des milieux terrestres et aquatiques est principalement causĂ©e par des Ă©missions de SO2, NOx et de NH3 Ă  l’atmosphĂšre. Ces polluants, une fois Ă©mis, sont transportĂ©s sur de longues distances, interagissent avec les composantes de l’atmosphĂšre avant de retomber au niveau du sol causant un changement d’aciditĂ© dans les milieux rĂ©cepteurs (i.e. terrestres et/ou aquatiques). Pour presque toute espĂšce vivante, il existe une plage de pH optimale pour le maintien de la vie. Une dĂ©viation de cet optimum est dommageable pour cette espĂšce et engendre un changement de la biodiversitĂ© dans les Ă©cosystĂšmes. L’analyse du cycle de vie (ACV) est un outil d’aide de prise Ă  la dĂ©cision qui permet d’évaluer les impacts potentiels d’un produit pour de nombreuses catĂ©gories d’impacts (e.g. changement climatique, toxicitĂ©, acidification). Pour ce faire, les mĂ©thodes d’évaluation des impacts du cycle de vie (ACVI) ont recours Ă  des facteurs de caractĂ©risation (FCs). Un FC se dĂ©finit comme Ă©tant la reprĂ©sentation mathĂ©matique de la chaine de cause Ă  effet d’une catĂ©gorie d’impact donnĂ©e. En considĂ©rant le cadre d’évaluation des impacts reliĂ©s aux Ă©missions atmosphĂ©riques (Udo de Haes et al., 2002), les FCs de la catĂ©gorie d’impact acidification ont Ă©tĂ© calculĂ©s par la somme des produits des facteurs de devenir atmosphĂ©rique associĂ©s Ă  un lieu d’émission, de facteurs de la sensibilitĂ© des sols ou de facteur de devenir des milieux rĂ©cepteurs (terrestres et aquatiques) associĂ©s aux milieux rĂ©cepteurs et de facteurs d’effet Ă©galement associĂ©s aux milieux rĂ©cepteurs. Le facteur de devenir atmosphĂ©rique Ă©value la relation entre la quantitĂ© de polluant Ă©mis et la quantitĂ© dĂ©posĂ©e en un lieu donnĂ©e. La sommation de ces derniers reprĂ©sente la fraction totale d’une Ă©mission transfĂ©rĂ©e Ă  l’ensemble des mileiux rĂ©cepteurs. Le facteur de sensibilitĂ© ou le facteur de devenir des milieux rĂ©cepteurs Ă©value la stabilitĂ© (mesurĂ©e, par exemple, par le pH) des milieux rĂ©cepteurs (terrestre et/ou aquatique) suivant les dĂ©positions de substances acidifiantes. Le facteur d’effet Ă©value le changement de biodiversitĂ© (e.g. perte d’espĂšces) du au changement de la qualitĂ© des milieux rĂ©cepteurs suite aux dĂ©positions acides. Ces facteurs sont calculĂ©s Ă  l’aide de plusieurs modĂšles mathĂ©matiques basĂ©s sur les sciences naturelles et dĂ©crivent la succession de processus chimiques, physiques et biologiques de la chaine cause-effet. Il existe deux approches de calculs pour les FCs : une approche dite problĂšme et une approche dite dommage. Cette derniĂšre approche modĂ©lise l’ensemble de la chaine cause-effet jusqu’aux dommages. La premĂšre approche (problĂšme) ne modĂ©lise qu’une partie de la chaine cause-effet; vii liant, par exemple, l’émission jusqu’à la dĂ©position dans les milieux rĂ©cepteurs ou jusqu’au changement de la qualitĂ© des Ă©cosystĂšmes. En thĂ©orie, cependant, les FCs orientĂ©s problĂšmes sont dĂ©finis comme un compromis maximisant la pertinence environnementale (pour la prise de dĂ©cision) et minimisant l’incertitude du modĂšle de caractĂ©risation. Plusieurs limitations ont Ă©tĂ© identifiĂ©es dans les mĂ©thodes ACVI actuelles. (i) La plupart des FCs retrouvĂ©s dans les mĂ©thodes ACVI actuelles sont basĂ©s sur de la modĂ©lisation rĂ©alisĂ©e Ă  une Ă©chelle continentale et sont de types problĂšmes. Cependant, ces FCs ne sont reprĂ©sentatifs que d’un lieu gĂ©ographique circonscrit (i.e. Canada, États-Unis, Europe ou Japon). Lors de la caractĂ©risation des Ă©missions du cycle de vie, l’hypothĂšse implicite posĂ©e a pour consĂ©quence que toutes les Ă©missions sont considĂ©rĂ©es comme ayant lieux dans ce lieu gĂ©ographique circonscrit (e.g. une Ă©mission de 1 kg de SO2 en Chine est Ă©quivalent Ă  1 kg SO2 en Europe). Avec la globalisation des marchĂ©s, cette hypothĂšse s’avĂšre inexacte. (ii) Le recours Ă  la modĂ©lisation basĂ©e sur une Ă©chelle continentale est problĂ©matique puisque les Ă©missions voyageant hors du contexte d’application ne sont pas considĂ©rĂ©es. Bien que cette dĂ©position transcontinentale reprĂ©sente, probablement, une faible proportion de la dĂ©position totale, il est possible que les dĂ©pĂŽts acides choient sur des milieux rĂ©cepteurs sensibles causant un impact important. (iii) Il existe un manque de cohĂ©rence entre les FCs de l’acidification terrestre de types problĂšme et dommage. En effet, les FCs problĂšmes sont basĂ©s sur un indicateur de type « charge critique » qui, pour le moment, ne peut ĂȘtre liĂ© Ă  une modĂ©lisation subsĂ©quente vers un indicateur de la perte de biodiversitĂ©. (iv) Il n’existe pas de FCs rĂ©gionalisĂ©s basĂ©s sur le devenir atmosphĂ©rique, le devenir des milieux rĂ©cepteurs et l’effet pour l’acidification aquatique. Par consĂ©quent, les impacts potentiels de l’acidification aquatique sont nĂ©gligĂ©s en ACV. (v) Les capacitĂ©s de modĂ©lisaiton de l’acidification terrestre sont limitĂ©s Ă  l’échelle nationale et celles de l’acidification aquatique sont inexistantes. (vi) Bien que la variabilitĂ© spatiale des FCs est gĂ©nĂ©ralement Ă©valuĂ©e, l’incertitude inhĂ©rentes aux FCs ne l’est pas. Sur la base de ces constats, les objectifs principaux ont Ă©tĂ© dĂ©finis: 1. CrĂ©er un modĂšle de caractĂ©risation rĂ©gionalisĂ© pour l’acidification terrestre et aquatique sur la base de modĂšles sophistiquĂ©s de devenir atmosphĂ©rique, de la sensibilitĂ©/devenir des milieux rĂ©cepteurs et d’effet Ă  une Ă©chelle mondiale. viii 2. GĂ©nĂ©rer des facteurs de devenir atmosphĂ©rique permettant de considĂ©rer la dĂ©position transcontinentale. 3. GĂ©nĂ©rer des facteurs de sensibilitĂ© terrestre compatible avec une phase subsĂ©quente vers un indicateur de la perte de biodiversitĂ©. 4. DĂ©velopper un modĂšle permettant d’évaluer le devenir des milieux rĂ©cepteurs pour l’acidification aquatique pouvant ĂȘtre combinĂ© aux courbes dose-rĂ©ponses, illustrant la perte de biodiversitĂ©, existantes. 5. GĂ©nĂ©rer des FCs rĂ©gionalisĂ©s, de type dommage, Ă  l’échelle globale pour l’acidification terrestre et aquatique. 6. Évaluer l’incertitude et la variation spatiale reliĂ©es aux FCs dĂ©veloppĂ©s afin de dĂ©finir et gĂ©nĂ©rer des FCs de type problĂšme Ă  l’échelle globale et supporter l’interprĂ©tation lors d’étude ACV. Pour ce faire, il fut nĂ©cessaire de crĂ©er un cadre mĂ©thodologique identifiant les indicateurs couvrant l’intĂ©gralitĂ© de chaĂźne cause-effet et les Ă©tapes de modĂ©lisation Ă  dĂ©velopper pour obtenir des facteurs de devenir atmosphĂ©rique rĂ©gionaux reliant l’émission Ă  la dĂ©position, des facteurs de sensibilitĂ© des sols reliant une dĂ©position atmosphĂ©rique Ă  un changement de pH des sols, des facteurs de devenir des milieux rĂ©cepteurs (pour l’acidification aquatique) reliant une dĂ©position atmosphĂ©rique Ă  un changement de pH dans les lacs et des facteurs d’effet (terrestres et aquatiques) afin de calculer des changements de biodiversitĂ© des espĂšces biologiques en fonction d’un changement de pH. Tous dĂ©veloppements ont Ă©tĂ© menĂ©s dans le but de calculer des FCs rĂ©gionalisĂ©s dommages, Ă  l’échelle globale, et d’en Ă©valuer la variabilitĂ© spatiale et l’incertitude. Un modĂšle de dispersion et de chimie atmosphĂ©rique mondial a Ă©tĂ© sĂ©lectionnĂ© pour servir de base Ă  la gĂ©nĂ©ration de facteurs de devenir atmosphĂ©rique. À l’aide de bilans de masse, il a Ă©tĂ© possible de crĂ©er une matrice source-rĂ©cepteur, dont les Ă©lĂ©ments sont des facteurs de devenir. Les rĂ©sultats ont montrĂ© que la dĂ©position transcontinentale reprĂ©sentait, en moyenne, prĂšs de 4% de la dĂ©position totale d’un continent. Un modĂšle simulant les processus gĂ©ochimiques des sols a servi pour Ă©valuer diffĂ©rents indicateurs chimiques des sols en rĂ©gime permanent. Pour ce faire, il fut cependant nĂ©cessaire de ix crĂ©er une base de donnĂ©es mondiale des paramĂštres de sols. Les rĂ©sultats ont montrĂ©s que le pH surlignait les zones les plus sensibles attendues et dĂ©montrait le moins de variation suite Ă  l’incertitude des paramĂštres de sols. Un modĂšle a Ă©tĂ© crĂ©Ă©e afin d’évaluer le pH des lacs Ă  travers le monde. Le modĂšle considĂšre que les lacs sont reprĂ©sentĂ©s par une sĂ©rie de rĂ©acteurs parfaitement mĂ©langĂ©s (CSTR). Il considĂšre les entrĂ©es d’ions H+ provenant de l’atmosphĂšre, des sols environnants ainsi que de l’eau en amont des lacs. Il considĂšre Ă©galement les sorties d’ions H+ suite au transport en aval des lacs et Ă  l’évaporation. Les facteurs d’effet terrestre et aquatique ont Ă©tĂ© gĂ©nĂ©rĂ©s Ă  partir de modĂšles de rĂ©gressions de diffĂ©rents Ă©cosystĂšmes Ă  travers le monde liant le pH Ă  la perte de biodiversitĂ© des plantes vasculaires, pour l’acidification terrestre, ou des poissons, pour l’acidification aquatique. Ces dĂ©veloppements mĂ©thodologiques ont donnĂ© comme rĂ©sultat 13104 FCs pour, respectivement, l’acidification terrestre et aquatique. Chaque FC peut dĂ©terminer l’impact potentiel d’une Ă©mission ayant lieu dans un grillage d’une rĂ©solution Ă©quivalente Ă  2ox2.5o partout sur la planĂšte. Des variations de 5 Ă  6 ordres de grandeurs et de 8 Ă  10 ordres de grandeurs pour respectivement l’acidification terrestre et aquatique ont Ă©tĂ© observĂ©es selon le lieu d’émission. L’incertitude des FCs dommages a Ă©tĂ© Ă©valuĂ©e Ă  plus d’un ordre de grandeurs (facteur 32) et Ă  prĂšs de 2 ordres de grandeurs pour l’acidification terrestre et aquatique, respectivement. De plus, les rĂ©sultats ont montrĂ© l’importance de considĂ©rer la dĂ©position transcontinentale. En effet, bien que cette derniĂšre reprĂ©sente prĂšs de 4% de la dĂ©position totale, elle est responsable de typiquement 15-17% et 44-58% de l’impact potentiel total de, respectivement, l’acidification terrestre et aquatique pour un lieu d’émission donnĂ©. En Ă©valuant la contribution des facteurs de devenir atmosphĂ©rique, de la sensibilitĂ© des sols ou du devenir dans les milieux rĂ©cepteurs et des effets Ă  la variabilitĂ© spatiale et Ă  l’incertitude du facteur de dommage, il a Ă©tĂ© possible de conclure que les FCs de type problĂšme doivent incorporer Ă  la fois le devenir atmosphĂ©rique et la sensibilitĂ© des sols ou, respectivement, le devenir des milieux rĂ©cepteurs. En effet, le facteur de devenir atmosphĂ©rique contribue peu Ă  la variabilitĂ© spatiale alors que le facteur d’effet contribue Ă  typiquement plus de 90% de l’incertitude totale. On en conclu qu’un FC portant sur la sensibilitĂ© des sols ou, respectivement, x du devenir des milieux rĂ©cepteurs s’avĂšre ĂȘtre le meilleur compromis entre la minimisation de l’incertitude et la maximisation de la pertinence environnementale et ce, tout en garantissant un lien cohĂ©rent entre les FCs problĂšmes et dommages. L’incertitude des FCs problĂšmes a Ă©tĂ© Ă©valuĂ©e Ă  un facteur 3 et un facteur 2 pour l’acidification terrestre et aquatique, respectivement. De plus, il a Ă©tĂ© montrĂ© qu’une Ă©valuation basĂ©e sur de la modĂ©lisation Ă  une l’échelle nationale, continentale ou mondiale engendrait une incertitude supplĂ©mentaire Ă©quivalente Ă  un ou deux ordres de grandeurs selon la rĂ©solution sĂ©lectionnĂ©e. Ainsi, cette thĂšse a proposĂ© un modĂšle de caractĂ©risation rĂ©gionalisĂ© Ă  l’échelle mondiale permettant la gĂ©nĂ©ration de FCs pouvant diffĂ©rentier davantage (comparativement aux FCs existants) les Ă©missions de substances acidifiantes tout en montrant l’importance i) des impacts potentiels provenant de la dĂ©position transcontinentale, ii) de la variabilitĂ© spatiale et iii) de l’incertitude et ce, pour l’acidification terrestre et aquatique. En ce sens, cette thĂšse permet d’amĂ©liorer les pratiques courantes de l’évaluation des impacts du cycle de vie de la catĂ©gorie d’impact acidification en ACV.----------Terrestrial and aquatic acidification are mostly caused by atmospheric emissions of SO2, NOx and NH3. Once emitted, these pollutants are transported over long distances, react with the atmospheric components before being deposited on receiving environments. Consequently, changes in their acidity levels may then be observed. For nearly every living species, there is an optimum pH. A serious deviation from this optimum can cause damages for this species and may thus result in a change of the ecosystem biodiversity. Life cycle assessment (LCA) is a decision making tool that allows for the evaluation of potential impacts of a product over numerous impact categories (e.g. climate change, toxicity, acidification). To do so, life cycle impact assessment methods (LCIA) use characterization factors (CFs). A CF is defined as a mathematical representation of the cause-effect chain of a given impact category. Considering the impact assessment framework for atmospheric emitted pollutants (Udo de Haes et al., 2002), acidification’s CFs were generated from the multiplication and subsequent sum of an atmospheric fate factor associated to a source location, a soil sensitivity or receiving environment fate factor related to receiving environments (terrestrial or aquatic, respectively) and effect factor also related to receiving environments. The atmospheric fate factor evaluates the source-receptor relationship. The sum of these factors represents to total fraction of the emission transferred to the receiving environments. The soil sensitivity or receiving environment fate factor evaluates the stability (measured, for example, with pH) of the receiving environment(s) following acid deposits. The effect factor evaluates the change in biodiversity loss caused by the recorded (or not) change in ecosystem quality. These factors are calculated from numerous mathematical models based on natural sciences and describe the cause-effect chain succession of chemical, physical and biological processes. There are two approaches to calculating CFs: a midpoint and an endpoint approach. Endpoint CFs model the entire cause-effect chain. The midpoint CFs only model a part of the cause-effect chain; linking for example, emission to atmospheric deposition or to changes in ecosystem quality. In theory, however, midpoint CFs are defined as the trade-off between the maximisation of environmental relevance and the minimisation of the characterization model uncertainties. xii Many limitations of the existing LCIA methods were identified. (i) Most CFs are based on continental modeling and evaluated with a midpoint approach. However, current CFs are only representative of a specific geographical context (i.e. Canada, United States of America, Europe or Japan). When characterizing life cycle emissions, it is assumed implicitly that they all occur within this geographical location (i.e. 1 kg of emitted SO2 in China is equivalent to 1 kg of emitted SO2 in Europe). With the globalization of markets, this represents an erroneous assumption. (ii) Continental scale modeling is problematic since emissions travelling in or from the considered continent are not considered. Even though transboundary deposition represent, in all likelihood, a small fraction of the total emissions, it is possible that acid deposits reach sensitive receiving environments and thus cause important potential impacts. (iii) There is also a lack of coherence between existing midpoint and endpoint terrestrial acidification CFs. Indeed, most midpoint CFs are based on a critical load approach, which, for the time being cannot be linked to a subsequent biodiversity loss modeling step. (iv) Spatially differentiated aquatic acidification CFs based on atmospheric fate, receiving environment fate and effect are nonexistent. Consequently, the potential impacts of acidifying emissions on aquatic environments are currently ignored by LCA case studies. (v) The terrestrial acidification CFs highest resolution is the country level while it is inexistent for aquatic acidification. (vi) While CFs spatial variability is typically evaluated, the CFs inherent uncertainty remains unevaluated. Consequently, the objectives of this project were defined: 1. Create a global scale characterization model for terrestrial and aquatic acidification based on sophisticated environmental models of atmospheric fate, soil sensitivity or receiving environment fate and effects. 2. Generate global scale fate factors enabling transboundary deposition evaluation. 3. Generate terrestrial sensitivity factors compatible with a subsequent biodiversity loss assessment. 4. Develop a model to assess aquatic acidification receiving environment fate which can be combined with existing biodiversity loss dose-response curves. 5. Generate terrestrial and aquatic regionalised endpoint CFs at a global scale. xiii 6. Evaluate the generated CFs spatial variability and the uncertainty to define and generate worldwide regionalised midpoint CFs and support the interpretation of impact assessment results in LCA case studies. To do so, we created a methodological framework i) specifying the required indicators to evaluate the entire cause-effect chain of terrestrial and aquatic acidification at a global scale and ii) listing the required modeling steps to obtain regional atmospheric fate factors, terrestrial sensitivity factors (linking an atmospheric deposition to a change in soil pH), receiving environment fate factors (linking an atmospheric deposition to a change in lake(s) pH) and effect factors (terrestrial and aquatic) to calculate changes in biodiversity loss according to a change in the receiving environment pH. Every development aimed to calculate regionalised endpoint CFs at a global scale and to evaluate both spatial variability and uncertainty. A global scale atmospheric chemistry model was selected to serve as a basis for the generation of atmospheric fate factors. With iterative mass balance calculations, we were able to generate source-receptor matrices whose elements are atmospheric fate factors. The results showed that transboundary deposition typically represented 4% of a continent total deposition. A model simulating soil geochemical processes served as a basis to evaluate steady-state soil chemical indicators. To do so, however, we needed to create a worldwide soil input parameter database. Results showed that pH highlighted expected sensitive areas and demonstrated less variations to soil input parameter uncertainty. A model was created to evaluate worldwide lakes pH. This model considers lakes as a series of interconnected continuously stirred reactor tanks (CSTR). It considers the H+ inputs from the atmosphere, from the surrounding soils and from upstream transport and considers the H+ outputs from downstream transport and evaporation. The terrestrial and aquatic effect factors were calculated from different model regressions, representing different ecosystems, linking pH to vascular plants (terrestrial acidification) or fishes (aquatic acidification) biodiversity loss. These methodological developments resulted in 13104 CFs for both terrestrial and aquatic acidification. Each CF can assess the potential impacts of the acidifying emissions from any worldwide 2ox2.5o grid. CFs can vary, across emission grids, by 5 to 6 orders of magnitude and 8 to 10 orders of magnitude for terrestrial and aquatic acidification, respectively. The endpoint CFs xiv uncertainty was established to more than an order of magnitude (factor 32) and about 2 orders of magnitude for terrestrial and aquatic acidification, respectively. Results also showed the importance of considering transboundary deposition. Indeed, while transboundary deposition only represented a share of 4% of a continent total deposition, the potential impacts of transboundary deposition represented, for an emission location, a share typically equal to 15-17% and 44-58% of the terrestrial and aquatic acidification total potential impacts, respectively. By analysing the contributions of the atmospheric fate, soil sensitivity or the receiving environment fate and effects factors to the endpoint CFs spatial variability and uncertainty, we defined midpoint CFs. These midpoints CFs consider the evaluation of both atmospheric fate and soil sensitivity or receiving environment fate for terrestrial and aquatic acidification, respectively. Indeed, the atmospheric fate factor did little to explain the endpoint CFs spatial variability and effect factors typically contributed to more than 90% of the total uncertainty. We thus concluded that a CF based on soil sensitivity or receiving environment fate represented the best trade-off between maximising environmental relevance and minimising uncertainty. These midpoint CFs also ensure a consistent link to endpoint CFs. The midpoint uncertainty was approximated by a factor 3 and a factor 2 for terrestrial and aquatic acidification, respectively. Furthermore, it was shown that an evaluation based on worldwide, continental or country resolutions CFs created an additional uncertainty equivalent to one or two orders of magnitude depending on the chosen resolution. Conclusively, this thesis presented a worldwide regionalised characterization model which generated CFs capable of greater (comparatively to existing CFs) acidifying emissions differentiation while showing the importance of i) the potential impacts from transboundary deposition, ii) spatial variability and iii) uncertainty for both terrestrial and aquatic acidification. Consequently, this thesis improves the LCIA current practices when assessing the potential impacts related to the acidification impact category

    L'écriture par gestes-piliers dans ma démarche compositionnelle

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    Tableau d’honneur de la FacultĂ© des Ă©tudes supĂ©rieures et postdoctorales, 2010-2011Ce mĂ©moire porte sur trois musiques de concert que j'ai composĂ©es entre 2006 et 2009. Il traite plus spĂ©cifiquement de l'Ă©criture par gestes-piliers dans la dĂ©marche compositionnelle qui a menĂ© Ă  leur rĂ©alisation. Au dĂ©part, ma rĂ©flexion sur la genĂšse de ces oeuvres - À propos des Ăźles de lumiĂšres, Cinq pamphlets pour ailleurs et Les fatras du contre-jour - a mis au jour l'importance du concept d'art dans ma dĂ©marche. J'ai aussi notĂ© que des notions comme intuition, intention, technique, imaginaire et projet esthĂ©tique sont essentielles Ă  la comprĂ©hension de ce concept. Je me suis Ă©galement penchĂ© plus spĂ©cifiquement sur ma mĂ©thode de composition : l'Ă©criture par gestes-piliers s'est rĂ©vĂ©lĂ©e comme l'axe principal de cette mĂ©thode. Je me suis alors questionnĂ© sur l'origine de ces gestes-piliers et j'ai identifiĂ© plusieurs sources d'influence, soit les musiques de VarĂšse, Scelsi, Sciarrino et Berio. Outre l'introduction et la conclusion, ce mĂ©moire est construit en deux parties : chapitre 1, l'Ă©noncĂ© des diffĂ©rents concepts nĂ©cessaires Ă  la comprĂ©hension de ma dĂ©marche compositionnelle et chapitre 2, l'illustration et l'analyse de l'Ă©criture par gestes-piliers dans les oeuvres Ă  l'Ă©tude

    ÉpidĂ©miologie de la maladie de Crohn au QuĂ©bec

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    Mémoire numérisé par la Direction des bibliothÚques de l'Université de Montréal

    A new experimental set-up for the study of the formation and dissociation of methane hydrate in sediments

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    methane hydrates ; sediments ; kinetics ; modelling ; heat transfer ; mass transfer ;International audienceIn this paper, we give a short presentation of the project ForDiMHyS which consists of experimental studies and model establishment (or development) of the kinetics of FORmation and Dissociation of Methane Hydrates in Sediments. We focus on the details of the experimental set-up which is newly, specially designed for this study in the preliminary step of the project. The four French academic teams and two PhD thesis are involved in the ForDiMHyS project on the period 2000-2004. The financial support is given by the five French Partners. The project consists of two-step programs; firstly the data acquisition from the laboratory experimental set-up and secondly simulation of methane production from methane hydrate fields

    Elastic Management of Byzantine Faults

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    International audienceTolerating byzantine faults on a large scale is a challenge: in particular, Desktop Grid environments sustain large numbers of faults that range from crashes to byzantine faults. Solutions in the literature that address byzantine failures are costly and none of them scales to really large numbers of nodes. This paper proposes to distribute task scheduling on trusted nodes in a Cloud network and to have these nodes assess the reliability of worker nodes by means of a reputation system. The resulting architecture is built for scalability and adapts costs to the workload associated with client requests

    Risk Score, Causes, and Clinical Impact of Failure of Transradial Approach for Percutaneous Coronary Interventions

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    ObjectivesTo study the causes of and to develop a risk score for failure of transradial approach (TRA) for percutaneous coronary intervention (PCI).BackgroundTRA-PCI failure has been reported in 5% to 10% of cases.MethodsTRA-PCI failure was categorized as primary (clinical reasons) or crossover failure. Multivariate analysis was performed to determine independent predictors of TRA-PCI failure, and an integer risk score was developed.ResultsFrom January to June 2010, TRA-PCI was attempted in 1,609 (97.3%) consecutive patients, whereas 45 (2.7%) had primary TRA-PCI failure. Crossover TRA-PCI failure occurred in 30 (1.8%) patients. Causes of primary TRA-PCI failure included chronic radial artery occlusion (11%), previous coronary artery bypass graft (27%), and cardiogenic shock (20%). Causes for crossover TRA-PCI failure included: inadequate puncture in 17 patients (57%); radial artery spasm in 5 (17%); radial loop in 4 (13%); subclavian tortuosity in 2 (7%); and inadequate guide catheter support in 2 (7%) patients. Female sex (odds ratio [OR]: 3.2; 95% confidence interval [CI]: 1.95 to 5.26, p < 0.0001), previous coronary artery bypass graft (OR: 6.1; 95% CI: 3.63 to 10.05, p < 0.0001), and cardiogenic shock (OR: 11.2; 95% CI: 2.78 to 41.2, p = 0.0011) were independent predictors of TRA-PCI failure. Risk score values from 0 to 7 predicted a TRA-PCI failure rate from 2% to 80%.ConclusionsIn a high-volume radial center, 2.7% of patients undergoing PCI are excluded from initial TRA on clinical grounds, whereas crossover to femoral approach is required in only 1.8% of the cases. A new simple clinical risk score is developed to predict TRA-PCI failure

    Risk of neonatal hypothyroidism in newborns from mothers exposed to CTPA during pregnancy: Ancillary data from a prospective outcome study

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    Background: Neonatal hypothyroidism is often raised as a potential concern for the use of computed tomography pulmonary angiography (CTPA) in pregnant women with suspected pulmonary embolism (PE). Objectives: To assess the incidence of neonatal hypothyroidism among newborns from mothers exposed to CTPA. Patients/methods: Pregnant women with clinically suspected PE were included in a multicenter, multinational prospective diagnostic management outcome study, based on pretest clinical probability assessment, high-sensitivity D-dimer testing, bilateral lower limb venous compression ultrasonography, and CTPA. Results of Guthrie tests were systematically collected for newborns of all women who required CTPA as part of the diagnostic strategy. A thyroid-stimulating hormone (TSH) level above 15 U/ml was used to define hypothyroidism. Results: Out of the 166 women included in the Swiss participating centers, 149 underwent a CTPA including 14 with twin pregnancies. Eight women suffered a pregnancy loss and results of the Guthrie test could not be retrieved for four newborns. All TSH levels were reported as being below 15 U/ml. The incidence of neonatal hypothyroidism was 0/151 (0.0%, 95% confidence interval: 0.0%-2.5%). Conclusions: We did not identify any cases of neonatal hypothyroidism in our cohort of 149 pregnant women investigated for suspected PE using a CTPA. Along with previous literature data, this provides further reassuring data regarding the use of CTPA in this indication. Keywords: Guthrie test; diagnosis; hypothyroidism; pregnancy; pulmonary embolism

    Novel Insights into the Bovine Polled Phenotype and Horn Ontogenesis in Bovidae

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    Despite massive research efforts, the molecular etiology of bovine polledness and the developmental pathways involved in horn ontogenesis are still poorly understood. In a recent article, we provided evidence for the existence of at least two different alleles at the Polled locus and identified candidate mutations for each of them. None of these mutations was located in known coding or regulatory regions, thus adding to the complexity of understanding the molecular basis of polledness. We confirm previous results here and exhaustively identify the causative mutation for the Celtic allele (PC) and four candidate mutations for the Friesian allele (PF). We describe a previously unreported eyelash-and-eyelid phenotype associated with regular polledness, and present unique histological and gene expression data on bovine horn bud differentiation in fetuses affected by three different horn defect syndromes, as well as in wild-type controls. We propose the ectopic expression of a lincRNA in PC/p horn buds as a probable cause of horn bud agenesis. In addition, we provide evidence for an involvement of OLIG2, FOXL2 and RXFP2 in horn bud differentiation, and draw a first link between bovine, ovine and caprine Polled loci. Our results represent a first and important step in understanding the genetic pathways and key process involved in horn bud differentiation in Bovidae
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