Morphological classification of post-AGB stars

We present a complete study of the morphology of post-Asymptotic Giant Branch (AGB) stars. Post-AGB is a very short evolutionary phase between the end of the AGB and the beginning of the Planetary Nebula (PN) stage (between 100 and 10,000 yrs). We have defined the end of the post-AGB phase and the beginning of the PN phase when the star is hot enough to fully ionize the hydrogen envelope. Post-AGB stars have a circumstellar shell that is illuminated by the central stars or partially ionized. However, this circumstellar shell is too small to be resolved from ground-based observations. Thus, we have used data from the Hubble Space Telescope (HST) database to resolve these shells. About 150 post-AGB were found in this database. Here we present the preliminary results on their morphological classification and the correlation with several parameters such as galactic latitude and IRAS fluxes. Our preliminary results show that 40% of the sample are stellar-like (S), 33 % bipolar (B), 12 % multi-polar (M) and 15 % elliptical (E).Comment: proceedings of the conference "Why Galaxies Care About AGB Stars II", Vienna 2010, eds. Franz Kerschbaum, Thomas Lebzelter and Bob Wing, ASP Conf.Ser (in press

Création de résumés de vidéos appliquée à la recherche par l'exemple

- Cet article décrit une méthode pour créer des résumés de vidéos possédant deux niveaux de résolution (intra-plan et inter-plan), à partir d'un descripteur couleur ou mouvement. Notre approche, applicable à tout autre type de descripteurs, consiste à extraire des images clés par regroupement de similarité suivant l'index considéré. Le regroupement non supervisé est réalisé par l'algorithme c-moyens flous (fuzzy c-means). Les résumés de vidéos ainsi obtenus permettent d'effectuer une recherche par l'exemple par combinaison d'index. La fusion est basée sur la théorie des ensembles flous qui définit la notion d'intersection des ensembles flous par l'utilisation d'une t-norme. Les résultats obtenus montrent que la recherche par l'exemple est améliorée par la combinaison des index

Simian virus 40 inhibits differentiation and maturation of rhesus macaque DC-SIGN+-dendritic cells

Dendritic cells (DC) are the initiators and modulators of the immune responses. Some species of pathogenic microorganisms have developed immune evasion strategies by controlling antigen presentation function of DC. Simian virus 40 (SV40) is a DNA tumor virus of rhesus monkey origin. It can induce cell transformation and tumorigenesis in many vertebrate species, but often causes no visible effects and persists as a latent infection in rhesus monkeys under natural conditions. To investigate the interaction between SV40 and rhesus monkey DC, rhesus monkey peripheral blood monocyte-derived DC were induced using recombinant human Interleukin-4 (rhIL-4) and infective SV40, the phenotype and function of DC-specific intracellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN)+ DC were analyzed by flow cytometry (FCM) and mixed lymphocyte reaction (MLR). Results showed that SV40 can down-regulate the expression of CD83 and CD86 on DC and impair DC-induced activation of T cell proliferation. These findings suggest that SV40 might also cause immune suppression by influencing differentiation and maturation of DC

Th1 Disabled Function in Response to TLR4 Stimulation of Monocyte-Derived DC from Patients Chronically-Infected by Hepatitis C Virus

Background: Lack of protective antibodies and inefficient cytotoxic responses are characteristics of chronic hepatitis C infection. A defect in dendritic cell (DC) function has thus been suspected, but this remains a controversial issue. Methods and Findings: Here we show that monocyte-derived DC (MoDC) from chronically-infected patients can mature in response to TLR1/2, TLR2/6 or TLR3 ligands. In contrast, when stimulated with the TLR4 ligand LPS, MoDC from patients show a profound defect in inducing IFNc secretion by allogeneic T cells. This defect is not due to defective phenotypic maturation or to the presence of HCV-RNA in DC or monocytes but is correlated to reduced IL-12 secretion by DC. Restoration of DC ability to stimulate IFNc secretion can be obtained by blocking MEK activation in DC, indicating that MEK/ ERK pathway is involved in the Th1 defect of MoDC. Monocytes from HCV patients present increased spontaneous secretion of cytokines and chemokines, especially MIP-1b. Addition of MIP-1b on healthy monocytes during differentiation results in DC that have Th1 defect characteristic of MoDC from HCV patients, suggesting that MIP-1b secretion by HCV monocytes participates in the Th1 defect of DC. Conclusions: Our data indicate that monocytes from HCV patients are activated in vivo. This interferes with their differentiation into DC, leading to deficient TLR4 signaling in these cells that are enable to induce a Th1 response. Thi

T-cell recognition of chemicals, protein allergens and drugs: towards the development of in vitro assays

Chemicals can elicit T-cell-mediated diseases such as allergic contact dermatitis and adverse drug reactions. Therefore, testing of chemicals, drugs and protein allergens for hazard identification and risk assessment is essential in regulatory toxicology. The seventh amendment of the EU Cosmetics Directive now prohibits the testing of cosmetic ingredients in mice, guinea pigs and other animal species to assess their sensitizing potential. In addition, the EU Chemicals Directive REACh requires the retesting of more than 30,000 chemicals for different toxicological endpoints, including sensitization, requiring vast numbers of animals. Therefore, alternative methods are urgently needed to eventually replace animal testing. Here, we summarize the outcome of an expert meeting in Rome on 7 November 2009 on the development of T-cell-based in vitro assays as tools in immunotoxicology to identify hazardous chemicals and drugs. In addition, we provide an overview of the development of the field over the last two decades

Video Summarization Based on Camera Motion and a Subjective Evaluation Method

We propose an original method of video summarization based on camera motion. It consists in selecting frames according to the succession and the magnitude of camera motions. The method is based on rules to avoid temporal redundancy between the selected frames. We also develop a new subjective method to evaluate the proposed summary and to compare different summaries more generally. Subjects were asked to watch a video and to create a summary manually. From the summaries of the different subjects, an "optimal" one is built automatically and is compared to the summaries obtained by different methods. Experimental results show the efficiency of our camera motion-based summary.</p

Mechanistic Insights on Acrylate Insertion Polymerization

Complexes [{(P∧O)PdMe}n] (1n; P∧O ) κ2-P,O-Ar2PC6H4SO2O with Ar ) 2-MeOC6H4) are a single-component precursor of the (P∧O)PdMe fragment devoid of additional coordinating ligands, which also promotes the catalytic oligomerization of acrylates. Exposure of 1n to methyl acrylate afforded the two diastereomeric chelate complexes [(P∧O)Pd{κ2-C,O-CH(C(O)OMe)CH2CH(C(O)OMe)CH2CH3}] (3-meso and 3-rac) resulting from two consecutive 2,1-insertions of methyl acrylate into the Pd-Me bond with the same or opposite stereochemistry, respectively, in a 3:2 ratio as demonstrated by comprehensive NMR spectroscopic studies and single crystal X-ray diffraction. These six-membered chelate complexes are direct key models for intermediates of acrylate insertion polymerization, and also ethylene-acrylate copolymerization to high acrylate content copolymers. Studies of the binding of various substrates (pyridine, dmso, ethylene and methyl acrylate) to 3-meso and 3-rac show that hindered displacement of the chelating carbonyl moiety by π-coordination of incoming monomer significantly retards, but does not prohibit, polymerization. For 3-meso,3-rac + C2H4 a 3-meso-C2H4, 3-rac-C2H4 an equilibrium constant K(353 K) ≈ 2 × 10-3 L mol-1 was estimated. Reaction of 3-meso, 3-rac with methyl acrylate afforded higher insertion products [(P∧O)Pd(C4H6O2)nMe] (n ) 3, 4) as observed by electrospray ionization mass spectrometry (ESI-MS). Theoretical studies by DFT methods of consecutive acrylate insertion provide relative energies of intermediates and transition states, which are consistent with the aforementioned experimental observations, and give detailed insights to the pathways of multiple consecutive acrylate insertions. Acrylate insertion into 3-meso,3-rac is associated with an overall energy barrier of ca. 100 kJ mol-1