328 research outputs found
The role of aerosol–radiation–cloud interactions in linking anthropogenic pollution over southern west Africa and dust emission over the Sahara
No full textNicolas Menut, L’Homme blanc. Les représentations de l’Occidental dans les arts non européens
No full textPar rapport aux nombreux travaux portant sur la représentation de l’altérité culturelle dans l’art occidental depuis les débuts de l’époque moderne, l’ouvrage de Nicolas Menut propose une inversion du regard en mettant sens dessus dessous la notion d’exotisme : il s’intéresse non à l’iconographie européenne du « bon sauvage » ou de l’« indigène », mais à la figuration du « Blanc » dans les arts des sociétés d’Afrique, d’Asie, des Amériques et d’Océanie. Vu d’ailleurs, l’Européen apparaît ain..
Nicolas Menut, L’Homme blanc. Les représentations de l’Occidental dans les arts non européens
No full textPar rapport aux nombreux travaux portant sur la représentation de l’altérité culturelle dans l’art occidental depuis les débuts de l’époque moderne, l’ouvrage de Nicolas Menut propose une inversion du regard en mettant sens dessus dessous la notion d’exotisme : il s’intéresse non à l’iconographie européenne du « bon sauvage » ou de l’« indigène », mais à la figuration du « Blanc » dans les arts des sociétés d’Afrique, d’Asie, des Amériques et d’Océanie. Vu d’ailleurs, l’Européen apparaît ain..
Bayesian Monte Carlo analysis applied to regional-scale inverse emission modeling for reactive trace gases
No full textInternational audience[1] The purpose of this article is inverse modeling of emissions at regional scale for photochemical applications. The study is performed for the Ile-de-France region over a two summers (1998 and 1999) period. This area represents an ideal framework since concentrated anthropogenic emissions in the Paris region frequently lead to the formation of urban plumes. The inversion method is based on Bayesian Monte Carlo analysis applied to a regional-scale chemistry transport model, CHIMERE. This method consists in performing a large number of successive simulations with the same model but with a distinct set of model input parameters at each time. Then a posteriori weights are attributed to individual Monte Carlo simulations by comparing them with observations from the AIRPARIF network: urban NO and O 3 concentrations and rural O 3 concentrations around the Paris area. For both NO and O 3 measurements, observations used for constraining Monte Carlo simulations are additionally averaged over the time period considered for analysis. The observational constraints strongly reduce the a priori uncertainties in anthropogenic NOx and volatile organic compounds (VOC) emissions: (1) The a posteriori probability density function (pdf) for NOx emissions is not modified in its average, but the standard deviation is decreased to around 20% (40% for the a priori one). (2) VOC emissions are enhanced (+16%) in the a posteriori pdf's with a standard deviation around 30% (40% for the a priori one). Uncertainties in the simulated urban NO, urban O 3 , and O 3 production within the plume are reduced by a factor of 3.2, 2.4, and 1.7, respectively. Citation: Deguillaume, L., M. Beekmann, and L. Menut (2007), Bayesian Monte Carlo analysis applied to regional-scale inverse emission modeling for reactive trace gases
A mosaic genetic screen for Drosophila neoplastic tumor suppressor genes based on defective pupation
No full textThe Drosophila neoplastic tumor suppressor genes (TSGs) coordinately control cell polarity and proliferation in epithelial and neuronal tissues. While a small group of neoplastic TSG mutations have been isolated and their corresponding genes cloned, the regulatory pathways that normally prevent inappropriate growth remain unclear. Identification of additional neoplastic TSGs may provide insight into this question. We report here the design of an efficient screen for isolating neoplastic TSG mutations utilizing genetically mosaic larvae. This screen is based on a defective pupation phenotype seen when a single pair of imaginal discs is homozygous for a neoplastic TSG mutation, which suggests that continuously proliferating cells can interfere with metamorphosis. Execution of this screen on two chromosome arms led to the identification of mutations in at least seven new neoplastic TSGs. The isolation of additional loci that affect hyperplastic as well as neoplastic growth indicates the utility of this screening strategy for studying epithelial growth control. Copyright © 2007 by the Genetics Society of America
Sobre l\u27activitat de la justícia a un menut poble valencià d\u27inicis del segle XV: Xixona (1413)
No full textComparative analysis of ESCRT-I, ESCRT-II and ESCRT-III function in Drosophila by efficient isolation of ESCRT mutants
No full textESCRT proteins were initially isolated in yeast as a single functional set of conserved components controlling endosomal cargo sorting and multivesicular body (MVB) biogenesis. Recent work has suggested that metazoan ESCRT proteins might have more functionally diverse roles, but the limited availability of ESCRT mutants in species other than yeast has hampered a thorough analysis. Here, we used a genetic screening strategy based on both cell-autonomous and non-autonomous growth-promotion phenotypes to isolate null mutations in nearly half of the ESCRT-encoding genes of Drosophila, including components of ESCRT-I, ESCRT-II and ESCRT-III complexes. All ESCRT components are required for trafficking of ubiquitylated proteins and are required to prevent excess Notch and EGFR signaling. However, cells lacking certain ESCRT-III components accumulate fewer ubiquitylated molecules in endosomes and display reduced degrees of cell proliferation compared with those lacking components of ESCRT-I and ESCRT-II. Moreover, although we find by ultrastructural analysis that MVB formation is impaired in ESCRT-I and ESCRT-II mutant cells, MVB biogenesis still occurs to some degree in ESCRT-III mutant cells. This work highlights the multiple cell biological and developmental roles of ESCRT proteins in Drosophila, suggests that the metazoan ESCRT-I, ESCRT-II and ESCRT-III complexes do not serve identical functions, and provides the basis for an extensive analysis of metazoan ESCRT function
Inverse modeling of surface NO x anthropogenic emission fluxes in the Paris area during the Air Pollution Over Paris Region (ESQUIF) campaign
No full textInternational audience[1] An inverse modeling approach has been developed to optimize urban NO x emission fluxes. We used the chemistry-transport model CHIMERE and its adjoint to develop a new methodology that includes kriging of measurements and a dynamic spatial aggregation model taking into account surface morphology of emission fluxes and ozone plumes to determine areas where emissions are inverted. This method is first applied to a seasonal approach over the Paris area. All emission fluxes were inverted hourly for the months of July and August of years 1998 and 1999. This leads to a significant reduction of the differences between simulated and measured concentrations of ozone and NO x. The results suggest that in the first-guess inventory, NO x fluxes are overestimated in the city of Paris and underestimated in the suburban areas. For the two periods the differences between optimized and first-guess profiles are about 15%. Comparisons between time profiles showed that Mondays and Wednesdays in August had characteristics that made them differ from the other days of the week. Two intensive observation periods of the Air Pollution Over Paris Region (ESQUIF) campaign are focused on and hourly results are discussed in order to refine the climatological results. Citation: Pison, I., L. Menut, and G. Bergametti (2007), Inverse modeling of surface NO x anthropogenic emission fluxes in the Paris area during the Air Pollution Over Paris Region (ESQUIF) campaign
Valorization of Galba oil (Calophyllum calaba L.) : isolation, characterization and biological properties of its active part
No full textDans un contexte de valorisation de la biodiversité, certaines espèces oléagineuses représentent une source intéressante de métabolites actifs. C’est le cas par exemple des espèces du genre Calophyllum qui sont utilisées en médecine traditionnelle pour leurs diverses propriétés. Elles ont déjà fait l’objet de nombreuses études afin de préciser leurs caractéristiques chimiques en relation avec leurs usages traditionnels. En Guadeloupe l’espèce la plus représentée est Calophyllum calaba L. ; l’huile de ses graines est utilisée pour traiter certaines affections dermatologiques (plaies, brûlures…) et lutter contre le vieillissement cutané. Au cours de ce travail, une méthode d’extraction a été mise au point afin de concentrer les métabolites secondaires de l’huile dans une partie appelée « résine ». Une étude chimique approfondie de cette résine a été réalisée par différentes techniques séparatives, analytiques et spectroscopiques. Des fractionnements successifs par chromatographie liquide/solide sur colonne de silice ont conduit à l’isolement de 14 composés. Des études analytiques et spectroscopiques ont permis de déterminer les structures de ces molécules, essentiellement de type pyranochromanone. Parmi ces composés, 4 correspondent à de nouvelles structures identifiées et décrites pour la première fois .L’huile de Galba, ses fractions et produits purs ont ensuite été testés pour leurs activités biologiques relatives à la sphère dermatologique. Leurs propriétés anti-oxydantes ont été déterminées par différentes méthodes in vitro : ORAC, DPPH, BCBT. L’activité anti-inflammatoire a été évaluée par dosage des nitrites et du TNF-α dans une culture cellulaire de macrophages stimulés par le LPS. La mesure de la concentration minimale inhibitrice de ces extraits sur 5 souches bactériennes impliquées dans des pathologies cutanées a permis d’évaluer leur activité antimicrobienne. Leur potentiel cicatrisant a été mis en évidence sur des cultures cellulaires de fibroblastes humains et de kératinocytes HaCaT, de même que leur influence sur la mélanogénèse. Enfin, l’évaluation de la capacité de certaines fractions à inhiber l’élastase et la collagénase montre l’intérêt de l’utilisation de l’huile pour ses propriétés anti-âge. Notre étude a permis de montrer que les activités biologiques de l’huile de Galba sont principalement liées aux métabolites secondaires de la résine. De plus, des précisions ont pu être apportées sur la nature des constituants impliqués dans les différentes activités biologiques étudiées.Ces résultats constituent un appui scientifique à l’utilisation traditionnelle de l’huile de Galba et permettent d’élargir son champ d’application dans le domaine dermocosmétique.In the context of biodiversity’s valorization, some oleaginous species are a good source of active metabolites. This is the case of Calophyllum species that are used in traditional medicine for their various properties. Many studies have been done on this botanical genus to clarify the chemical composition but also the biological activities of various parts of these plants. In Guadeloupe, Calophyllum calaba L. is the most widespread species, the oil from its seeds is used to treat certain skin problems (wounds, burns ...) and prevent skin aging.During this study, a method of extraction was developed to concentrate the secondary metabolites of the oil in a part called "resin".A thorough study of the chemical compounds of the resin was carried out by various analytical and spectroscopic techniques. Successive fractionations by liquid/solid chromatography on silica column led to the isolation of fourteen compounds. Extensive analytical and spectroscopic studies allowed to know the structures of these molecules which were essentially pyranochromanone type. Among these compounds, four of them correspond to new structures identified and described for the first time.Galba Oil, its fractions and pure products were then tested for different biological activities relative to the dermatological field. The antioxidant properties were determined by various in vitro methods: ORAC, DPPH, BCBT. The anti-inflammatory activity was assessed by determination of nitrite and TNF-α in cell culture of macrophages stimulated by LPS. The measurement of the minimal inhibitory concentration of these extracts on 5 bacterial strains involved in cutaneous pathologies allowed to know their antimicrobial activity. Their wound-healing potential has been demonstrated in cell cultures of human fibroblasts and keratinocytes HaCaT, as well as their action on melanogenesis. Finally, the ability of certain fractions to inhibit elastase and collagenase may be related to the use of this oil for its anti-aging properties.Our study has shown that most of biological activities were linked to the secondary metabolites of the resin. In addition, some clarifications were made on the nature of the constituents involved in the different biological activities which were studied.These results provide scientific support to the traditional use of Galba oil and broaden its use in the dermocosmetic area
Phase separation dynamics of gluten protein mixtures
No full textWe investigate by time-resolved synchrotron ultra-small X-ray scattering the dynamics of liquid-liquid phase-separation (LLPS) of gluten protein suspensions following a temperature quench. Samples at a fixed concentration (237 mg ml-1) but with different protein compositions are investigated. In our experimental conditions, we show that fluid viscoelastic samples depleted in polymeric glutenin phase-separate following a spinodal decomposition process. We quantitatively probe the late stage coarsening that results from a competition between thermodynamics that speeds up the coarsening rate as the quench depth increases and transport that slows down the rate. For even deeper quenches, the even higher viscoelasticity of the continuous phase leads to a "quasi" arrested phase separation. Anomalous phase-separation dynamics is by contrast measured for a gel sample rich in glutenin, due to elastic constraints. This work illustrates the role of viscoelasticity in the dynamics of LLPS in protein dispersions
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