An upper limit for the water outgassing rate of the main-belt comet 176P/LINEAR observed with Herschel/HIFI

in Astronomy and Astrophysics (2012), 546

176P/LINEAR is a member of the new cometary class known as main-belt comets (MBCs). It displayed cometary activity shortly during its 2005 perihelion passage, which may be driven by the sublimation of ... [more ▼]

176P/LINEAR is a member of the new cometary class known as main-belt comets (MBCs). It displayed cometary activity shortly during its 2005 perihelion passage, which may be driven by the sublimation of subsurface ices. We have therefore searched for emission of the H[SUB]2[/SUB]O 1[SUB]10[/SUB]-1[SUB]01[/SUB] ground state rotational line at 557 GHz toward 176P/LINEAR with the Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory on UT 8.78 August 2011, about 40 days after its most recent perihelion passage, when the object was at a heliocentric distance of 2.58 AU. No H[SUB]2[/SUB]O line emission was detected in our observations, from which we derive sensitive 3-σ upper limits for the water production rate and column density of <4 × 10[SUP]25[/SUP] mol s[SUP]-1[/SUP] and of <3 × 10[SUP]10[/SUP] cm[SUP]-2[/SUP], respectively. From the peak brightness measured during the object's active period in 2005, this upper limit is lower than predicted by the relation between production rates and visual magnitudes observed for a sample of comets at this heliocentric distance. Thus, 176P/LINEAR was most likely less active at the time of our observation than during its previous perihelion passage. The retrieved upper limit is lower than most values derived for the H[SUB]2[/SUB]O production rate from the spectroscopic search for CN emission in MBCs. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. [less ▲]

Spitzer Transits Of The Super-Earth Gj1214b And Implications For Its Atmosphere

in AAS/Division for Planetary Sciences Meeting Abstracts (2012, October 01)

We observed the transiting super-Earth exoplanet GJ1214b using Warm Spitzer at 4.5 μm wavelength during a 20-day quasi-continuous sequence in May 2011. The goals of our long observation were to accurately ... [more ▼]

We observed the transiting super-Earth exoplanet GJ1214b using Warm Spitzer at 4.5 μm wavelength during a 20-day quasi-continuous sequence in May 2011. The goals of our long observation were to accurately define the infrared transit radius of this nearby super-Earth, to search for the secondary eclipse, and to search for other transiting planets in the habitable zone of GJ1214. We here report results from the transit monitoring of GJ1214b, including a re-analysis of previous transit observations by Desert et al. (2011). In total, we analyze 14 transits of GJ1214b at 4.5 μm, 3 transits at 3.6 μm, and 7 new ground-based transits in the I+z band. Our new Spitzer data by themselves eliminate cloudless solar composition atmospheres for GJ1214b, and methane-rich models from Howe & Burrows (2012). Using our new Spitzer measurements to anchor the observed transit radii of GJ1214b at long wavelengths, and adding new measurements in I+z, we evaluate models from Benneke & Seager (2012) and Howe & Burrows (2012) using a χ2 analysis. We find that the best-fit model exhibits an increase in transit radius at short wavelength due to Rayleigh scattering. Pure water atmospheres are also possible. However, a flat line (no atmosphere detected) remains among the best of the statistically acceptable models, and better than pure water atmospheres. We explore the effect of systematic differences among results from different observational groups, and we find that the flat line model is the least sensitive to systematic error. [less ▲]

Brèves considérations relatives à l'intégration européenne : l'Union européenne et le Conseil de l'Europe

Learning material (2012)

Cette brève contribution dresse un portrait général des deux moteurs de l'intégration européenne : l'Union européenne et le Conseil de l'Europe.

Evidence for a partial epithelial-mesenchymal transition in rat auditory organ development

Poster (2012, October 01)

An epithelial-mesenchymal transition is a biological process that allows a polarized epithelial cell to undergo multiple biochemical changes that enable it to assume a mesenchymal cell phenotype. During ... [more ▼]

An epithelial-mesenchymal transition is a biological process that allows a polarized epithelial cell to undergo multiple biochemical changes that enable it to assume a mesenchymal cell phenotype. During this process, epithelial cells loosen cell-cell adhesion, module their polarity and rearrange their cytoskeleton: intermediate filaments typically switch from cytokeratin to vimentin. They also enhance their motility capacity. The epithelial-mesenchymal transition plays key roles in the formation of the body plan and in the differentiation of multiple tissues and organs but it is also involved in tissue repair, tissue homeostasis, fibrosis, and carcinoma progression. Until now, epithelial-mesenchymal transition has been rarely mentioned in the inner ear organogenesis. In chick, epithelial-mesenchymal transition has been reported as a possible mechanism of semicircular canal morphogenesis. More recently, an in vitro study has also indicated that sensory epithelial cells from mouse utricle can undergo an epithelial-mesenchymal transition to become cells expressing features of prosensory cells. By contrast, epithelial-mesenchymal transition has never been observed during auditory organ morphogenesis. The auditory organ, the organ of Corti, is a highly specialized structure composed by specific cellular types. The sensory cells are characterized by stereocilia at their apex and are necessary for the sound perception. Theses cells are supported by supporting cells. Based on their morphology and physiology, at least four types of supporting cells can be identified in the organ of Corti: inner and outer pillar cells, phalangeal cell and Deiter’s cells. The inner pillar cells and outer pillar cells combine to form the tunnel of Corti, a fluid filled triangular space that separates the single row of inner hair cells from the first row of outer hair cells. The Nuel spaces are another interval in the organ of Corti that is situated between the outer pillar cells and the different rows of outer hair cells and Deiters cells. To determine whether an epithelial-mesenchymal transition may play a role in the morphogenesis of the auditory organ, we studied the spatial localization of several epithelial-mesenchymal transition markers, the cell-cell adhesion molecules and intermediate filament cytoskeletal proteins, in epithelium of the dorsal cochlea during development of the rat organ of Corti from 18th embryonic day until 25th postnatal day. We examined by confocal microscopy immunolabelings on cryosections of whole cochleae with antibodies anti-cytokeratins as well as with antibodies anti-vimentin, anti-E-cadherin and anti-beta-catenin.Our results showed a partial loss of E-cadherin and beta-catenin between supporting cells at P8 and P12, respectively, and a temporary appearance of vimentin in pillar cells and Deiters between P8 and P10. Our results show a local loss of adhesion between supporting cells of the OC from P8, an increase expression of cytokeratins in supporting cells around P10 and a temporary appearance of vimentin in supporting cells at P8-10. These observations suggest that a partial epithelial-mesenchymal transition might be involved in the remodeling of the Corti organ during the postnatal stages of development in rat. [less ▲]

Hot circumstellar material resolved around β Pic with VLTI/PIONIER

in Astronomy and Astrophysics (2012), 546

Aims: We aim at resolving the circumstellar environment around β Pic in the near-infrared in order to study the inner planetary system (<200 mas, i.e., ~4 AU). Methods: Precise interferometric fringe ... [more ▼]

Aims: We aim at resolving the circumstellar environment around β Pic in the near-infrared in order to study the inner planetary system (<200 mas, i.e., ~4 AU). Methods: Precise interferometric fringe visibility measurements were obtained over seven spectral channels dispersed across the H band with the four-telescope VLTI/PIONIER interferometer. Thorough analysis of interferometric data was performed to measure the stellar angular diameter and to search for circumstellar material. Results: We detected near-infrared circumstellar emission around β Pic that accounts for 1.37% ± 0.16% of the near-infrared stellar flux and that is located within the field-of-view of PIONIER (i.e., ~200 mas in radius). The flux ratio between this excess and the photosphere emission is shown to be stable over a period of 1 year and to vary only weakly across the H band, suggesting that the source is either very hot (≳1500 K) or dominated by the scattering of the stellar flux. In addition, we derive the limb-darkened angular diameter of β Pic with an unprecedented accuracy (θLD= 0.736 ± 0.019 mas). Conclusions: The presence of a small H-band excess originating in the vicinity of β Pic is revealed for the first time thanks to the high-precision visibilities enabled by VLTI/PIONIER. This excess emission is likely due to the scattering of stellar light by circumstellar dust and/or the thermal emission from a yet unknown population of hot dust, although hot gas emitting in the continuum cannot be firmly excluded. [less ▲]

The 2.35 year itch of Cygnus OB2 #9. I. Optical and X-ray monitoring

in Astronomy and Astrophysics (2012), 546

Context. Nonthermal radio emission in massive stars is expected to arise in wind-wind collisions occurring inside a binary system. One such case, the O-type star Cyg OB2 #9, was proven to be a binary only ... [more ▼]

Context. Nonthermal radio emission in massive stars is expected to arise in wind-wind collisions occurring inside a binary system. One such case, the O-type star Cyg OB2 #9, was proven to be a binary only four years ago, but the orbital parameters remained uncertain. The periastron passage of 2011 was the first one to be observable under good conditions since the discovery of binarity. <BR /> Aims: In this context, we have organized a large monitoring campaign to refine the orbital solution and to study the wind-wind collision. <BR /> Methods: This paper presents the analysis of optical spectroscopic data, as well as of a dedicated X-ray monitoring performed with Swift and XMM-Newton. <BR /> Results: In light of our refined orbital solution, Cyg OB2 #9 appears as a massive O+O binary with a long period and high eccentricity; its components (O5-5.5I for the primary and O3-4III for the secondary) have similar masses and similar luminosities. The new data also provide the first evidence that a wind-wind collision is present in the system. In the optical domain, the broad Hα line varies, displaying enhanced absorption and emission components at periastron. X-ray observations yield the unambiguous signature of an adiabatic collision, because as the stars approach periastron, the X-ray luminosity closely follows the 1/D variation expected in that case. The X-ray spectrum appears, however, slightly softer at periastron, which is probably related to winds colliding at slightly lower speeds at that time. <BR /> Conclusions: It is the first time that such a variation has been detected in O+O systems, and the first case where the wind-wind collision is found to remain adiabatic even at periastron passage. [less ▲]

Gene expression profiles in canine idiopathic pulmonary fibrosis

in Proceedings of 17th International consortium on lung and airways fibrosis (2012, October 01)

The relationships between anomia and short-term memory deficits

Poster (2012, October)

Anomia is the most common symptom of language dysfunction occurring in aphasia. Moreover, verbal short-term memory (STM) impairments are a frequent characteristic of aphasic syndromes. However, the nature ... [more ▼]

Anomia is the most common symptom of language dysfunction occurring in aphasia. Moreover, verbal short-term memory (STM) impairments are a frequent characteristic of aphasic syndromes. However, the nature of these deficits and their relationships to language production impairments in these patients are still debated. Recent STM models have been proposed incorporating relationships between language representations and STM, including distinct capacities for temporary storage of phonological and lexical-semantic information (N. Martin & Saffran, 1992; R. Martin, Lesch, & Bartha, 1999). This study explores the relationships between anomia and STM deficits. We assume that a naming impairment may be related to either a phonological STM impairment with preserved lexical-semantic STM or to an impaired lexical-semantic STM with preserved phonological STM. We tested these predictions in two aphasic patients, BN and TM. Phonological STM was assessed using a rhyme-probe task (R. Martin et al., 1999) and a lexical-decision task, each target word being preceded by a phonologically related prime word. Lexical-semantic STM was assessed by a category-probe task and a lexical-decision task with semantically related primes. BN was impaired on the rhyme-probe task and presented a reversed phonological priming effect, suggesting phonological STM impairment. However, she presented normal performance on the category-probe task and a normal semantic priming effect. By contrast, TM performed normally on the rhyme-probe and phonological lexical-decision tasks but was impaired on the category-probe task and presented no semantic priming effect, indicating lexical-semantic STM impairment. Moreover, both patients’ word retrieval capacity, as assessed with a picture naming task, was impaired. BN produced phonological paraphasias, repetitive self-corrections and presented an increased length effect. We assume that BN’s errors and effects may be related to her phonological STM deficit. TM instead produced semantic paraphasias, omissions and circumlocutions and presented an increased frequency effect. These errors and effects may be related to his lexical-semantic STM deficit. Results show a double dissociation between phonological and lexical-semantic STM deficits. Furthermore, the patients’ naming patterns seem to indicate that their naming impairment may be related to a selective STM deficit. The results are discussed within the STM framework of N. Martin and Saffran (1992). Martin, N., & Saffran, E. (1992). A computational account of deep dysphasia: evidence from a single case study. Brain and Language, 43(1), 240-274. Martin, R. C., Lesch, M. F., & Bartha, M. C. (1999). Independence of input and output phonology in word processing and short-term memory. Journal of Memory and Language, 41(1), 3-29. [less ▲]

Characterization of the resistance of SJL/J mice to pneumonia virus of mice, a model for infantile bronchiolitis due to a respiratory syncytial virus

in PLoS ONE (2012), 7(10), 44581

Respiratory syncytial virus (RSV), a prominent cause of airway morbidity in children, maintains an excessive hospitalization rate despite decades of research. Host factors are assumed to influence the ... [more ▼]

Respiratory syncytial virus (RSV), a prominent cause of airway morbidity in children, maintains an excessive hospitalization rate despite decades of research. Host factors are assumed to influence the disease severity. As a first step toward identifying the underlying resistance mechanisms, we recently showed that inbred mouse strains differ dramatically as regards their susceptibility to pneumonia virus of mice (PVM), the murine counterpart of RSV. PVM infection in mice has been shown to faithfully mimic the severe RSV disease in human infants. This study aimed at dissecting the remarkable PVM-resistance shown by the SJL/J strain. To characterize its genetic component, we assessed clinical, physiopathological, and virological resistance/susceptibility traits in large first (F1) and second (F2) generations obtained by crossing the SJL/J (resistant) and 129/Sv (susceptible) strains. Then, to acquire conclusive in vivo evidence in support of the hypothesis that certain radiosensitive hematopoietic cells might play a significant role in PVM-resistance, we monitored the same resistance/susceptibility traits in mock- and γ-irradiated SJL/J mice. Segregation analysis showed that (i) PVM-resistance is polygenic, (ii) the resistance alleles are recessive, and (iii) all resistance-encoding alleles are concentrated in SJL/J. Furthermore, there was no alteration of SJL/J PVM resistance after immunosuppression by γ-irradiation, which suggests that adaptive immunity is not involved. We conclude that host resistance to pneumoviruses should be amenable to genetic dissection in this mouse model and that radioresistant lung epithelial cells and/or alveolar macrophages may control the clinical severity of pneumovirus-associated lung disease. [less ▲]

Xérogels de carbone à base de résorcinol-formaldéhyde en tant que matériaux d’anode pour batterie Li-ion : influence de la porosité sur la capacité et le comportement lors des cycles d’insertion-désinsertion

Conference (2012, October)