102 research outputs found
Chiral Perturbation Theory
An introduction to the methods and ideas of Chiral Perturbation Theory is
presented in this talk. The discussion is illustrated with some
phenomenological predictions that can be compared with available experimental
results.Comment: 16 pages, 4 Postscript figures, uses epsf.sty. Talk presented at the
International Conference on Particle Physics and Astrophysics in The Standard
Model and Beyond, Bystra (Poland). Full Postscript file available at
http://deneb.ugr.es/papers/ugft57.ps.g
Path-tracing Monte Carlo Library for 3D Radiative Transfer in Highly Resolved Cloudy Atmospheres
Interactions between clouds and radiation are at the root of many
difficulties in numerically predicting future weather and climate and in
retrieving the state of the atmosphere from remote sensing observations. The
large range of issues related to these interactions, and in particular to
three-dimensional interactions, motivated the development of accurate radiative
tools able to compute all types of radiative metrics, from monochromatic, local
and directional observables, to integrated energetic quantities. In the
continuity of this community effort, we propose here an open-source library for
general use in Monte Carlo algorithms. This library is devoted to the
acceleration of path-tracing in complex data, typically high-resolution
large-domain grounds and clouds. The main algorithmic advances embedded in the
library are those related to the construction and traversal of hierarchical
grids accelerating the tracing of paths through heterogeneous fields in
null-collision (maximum cross-section) algorithms. We show that with these
hierarchical grids, the computing time is only weakly sensitivive to the
refinement of the volumetric data. The library is tested with a rendering
algorithm that produces synthetic images of cloud radiances. Two other examples
are given as illustrations, that are respectively used to analyse the
transmission of solar radiation under a cloud together with its sensitivity to
an optical parameter, and to assess a parametrization of 3D radiative effects
of clouds.Comment: Submitted to JAMES, revised and submitted again (this is v2
Utilisation de la grille pour la simulation de température de brillance dans une atmosphÚre nuageuse composée de cirrus
Utilisation de la grille pour la simulation de température de brillance dans une atmosphÚre nuageuse composée de cirru
Establishment of an analytical model for remote sensing of typical stratocumulus cloud profiles under various precipitation and entrainment conditions
Structural patterns of cloud effective radius (ER) and liquid water content (LWC) profiles are essential variables of cloud lifecycle and precipitation processes, while observing cloud profiles from passive remote sensing sensors remains highly challenging. Understanding whether there exist typical structural patterns of ER and LWC profiles in liquid clouds and how they link with cloud entrainment or precipitating status is critical in developing algorithms to derive cloud profiles from passive satellite sensors. This study aims to address these questions and provide a preliminary foundation for the develop-ment of liquid cloud profile retrievals for the Multi-viewing, Multi-channel and Multi-polarization Imaging (3MI) sensor aboard the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) Polar System-Second Generation (EPS-SG) satellite, which is scheduled to be launched in 2025. Firstly, we simulate a large ensemble of strato-cumulus cloud profiles using the Colorado State University (CSU) Regional Atmospheric Modeling System (RAMS). The empirical orthogonal function (EOF) analysis is adopted to describe the shape of simulated profiles with a limited number of elemental profile variations. Our results indicate that the first three EOFs of LWC and ER profiles can explain >90 % of LWC and ER profiles. The profiles are classified into four prominent patterns and all of these patterns can be simplified as triangle-shaped polylines. The frequency of these four patterns is found to relate to intensities of the cloud-top entrainment and precipitation. Based on these analyses, we propose a simplified triangle-shape cloud profile parameterization scheme allowing to represent these main patterns of LWC and ER. This simple yet physically realistic analytical model of cloud profiles is expected to facilitate the representation of cloud properties in advanced retrieval algorithms such as those devel-oped for the 3MI/EPS-SG.</p
Les choix organisationnels des propriétaires de chevaux de loisir dans les espaces ruraux
La possession dâĂ©quidĂ©s de loisir a rĂ©cemment connu un essor important. Pour entretenir ces animaux, leurs propriĂ©taires peuvent soit les prendre en charge eux-mĂȘmes, soit faire appel Ă des prestataires de services marchands. Les assimilant Ă des producteurs de leur propre loisir, nous proposons dâĂ©tudier les dĂ©terminants de leur choix organisationnel grĂące aux thĂ©ories traitant habituellement des frontiĂšres de la firme. Les 251 enquĂȘtes rĂ©alisĂ©es dĂ©montrent la pertinence de lâapplication de ces cadres dâanalyse Ă la production domestique. Les propriĂ©taires dâĂ©quidĂ©s poursuivent un objectif dâefficience. Ils cherchent Ă maximiser leur utilitĂ©, tout en minimisant leurs coĂ»ts de production et de transaction et en sâadaptant aux ressources auxquelles ils peuvent avoir accĂšs.The number of recreational Equidae owners has recently increased sharply. These owners can choose between stabling and caring for their animals domestically, on their own property, or using professional service suppliers. By considering them as producers of their own leisure activity, we proposed to study the parameters involved in this choice using theories usually employed to analyze firm boundaries. Results from our 251 inquiries demonstrated the relevance of transposing these theoretical tools to domestic production. Equidae owners pursue an objective of efficiency. They aim at maximizing their utility while minimizing their production and transaction costs and adapting to resources they can access
Sprouty1, a new target of the angiostatic agent 16K prolactin, negatively regulates angiogenesis
BACKGROUND:Disorganized angiogenesis is associated with several pathologies, including cancer. The identification of new genes that control tumor neovascularization can provide novel insights for future anti-cancer therapies. Sprouty1 (SPRY1), an inhibitor of the MAPK pathway, might be one of these new genes. We identified SPRY1 by comparing the transcriptomes of untreated endothelial cells with those of endothelial cells treated by the angiostatic agent 16K prolactin (16K hPRL). In the present study, we aimed to explore the potential function of SPRY1 in angiogenesis.RESULTS:We confirmed 16K hPRL induced up-regulation of SPRY1 in primary endothelial cells. In addition, we demonstrated the positive SPRY1 regulation in a chimeric mouse model of human colon carcinoma in which 16K hPRL treatment was shown to delay tumor growth. Expression profiling by qRT-PCR with species-specific primers revealed that induction of SPRY1 expression by 16K hPRL occurs only in the (murine) endothelial compartment and not in the (human) tumor compartment. The regulation of SPRY1 expression was NF-kappaB dependent. Partial SPRY1 knockdown by RNA interference protected endothelial cells from apoptosis as well as increased endothelial cell proliferation, migration, capillary network formation, and adhesion to extracellular matrix proteins. SPRY1 knockdown was also shown to affect the expression of cyclinD1 and p21 both involved in cell-cycle regulation. These findings are discussed in relation to the role of SPRY1 as an inhibitor of ERK/MAPK signaling and to a possible explanation of its effect on cell proliferation.CONCLUSIONS:Taken together, these results suggest that SPRY1 is an endogenous angiogenesis inhibitor
3D cloud envelope and cloud development velocity from simulated CLOUD (C3IEL) stereo images
A method to derive the 3D cloud envelope and the cloud development velocity from high spatial and temporal resolution satellite imagery is presented. The CLOUD instrument of the recently proposed C3IEL mission lends itself well to observing at high spatial and temporal resolutions the development of convective cells. Space-borne visible cameras simultaneously image, under multiple view angles, the same surface domain every 20âs over a time interval of 200âs. In this paper, we present a method for retrieving cloud development velocity from simulated multi-angular, high-resolution top of the atmosphere (TOA) radiance cloud fields. The latter are obtained via the image renderer Mitsuba for a cumulus case generated via the atmospheric research model SAM and via the radiative transfer model 3DMCPOL, coupled with the outputs of an orbit, attitude, and camera simulator for a deep convective cloud case generated via the atmospheric research model Meso-NH. Matching cloud features are found between simulations via block matching. Image coordinates of tie points are mapped to spatial coordinates via 3D stereo reconstruction of the external cloud envelope for each acquisition. The accuracy of the retrieval of cloud topography is quantified in terms of RMSE and bias that are, respectively, less than 25 and 5âm for the horizontal components and less than 40 and 25âm for the vertical components. The inter-acquisition 3D velocity is then derived for each pair of tie points separated by 20âs. An independent method based on minimising the RMSE for a continuous horizontal shift of the cloud top, issued from the atmospheric research model, allows for the obtainment of a ground estimate of the velocity from two consecutive acquisitions. The mean values of the distributions of the stereo and ground velocities exhibit small biases. The width of the distributions is significantly different, with higher a distribution width for the stereo-retrieved velocity. An alternative way to derive an average velocity over 200âs, which relies on tracking clusters of points via image feature matching over several acquisitions, was also implemented and tested. For each cluster of points, mean stereo and ground positions were derived every 20âs over 200âs. The mean stereo and ground velocities, obtained as the slope of the line of best fit to the mean positions, are in good agreement.</p
Clinical Impact of Antifungal Susceptibility, Biofilm Formation and Mannoside Expression of Candida Yeasts on the Outcome of Invasive Candidiasis in ICU: An Ancillary Study on the Prospective AmarCAND2 Cohort
Background: The link between Candida phenotypical characteristics and invasive candidiasis (IC) prognosis is still partially unknown.Methods:Candida strains isolated during the AmarCAND2 study were centrally analyzed for species identification, antifungal susceptibility, biofilm formation, and expression of surface and glycoconjugate mannosides. Correlation between these phenotypical features and patient outcome was sought using a multivariable Cox survival model.Results:Candida albicans was predominant (65.4%, n = 285), with a mortality rate significantly lower than that in patients with non-albicans strains [HR 0.67 (0.46â1.00), p = 0.048]. The rate of fluconazole-resistant strains was low (C. albicans and Candida glabrata: 3.5 and 6.2%, respectively) as well as caspofungin-resistant ones (1 and 3.1%, respectively). Early biofilm formation was less frequent among C. albicans (45.4%) than among non-albicans (81.2%). While the strains of C. albicans showed variable levels of surface mannosides expression, strains isolated from candidemia exhibited a high expression of ÎČ-man, which was correlated with an increased mortality (p = 0.02).Conclusion:Candida albicans IC were associated with lower mortality, and with strains that exhibited less frequently early biofilm formation than non-albicans strains. A high expression of ÎČ-man was associated with increased IC mortality. Further studies are warranted to confirm this data and to evaluate other virulence factors in yeasts
Alimentation du nourrisson (évolution et place des recommandations nutritionnelles dans la pratique quotidienne du médecin généraliste et application par les parents)
PARIS6-Bibl.PitiĂ©-SalpĂȘtrie (751132101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF
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