Study of the scientific potential of a three 40 cm Telescopes Interferometer at Dome C

Recent site testing (see: http://www-luan.unice.fr/Concordiastro/indexantartic.html) has shown that Dome C in Antarctica might have a high potential for stellar interferometry if some solutions related to the surface atmospheric layer are found. A demonstrator interferometer could be envisioned in order to fully qualify the site and prepare the future development of a large array. We analyse the performances of a prototype interferometer for Dome C made with 3 telescopes of 40 cm diameter. It assumes classical Michelson recombination. The most recent atmospheric and environmental conditions measured at Dome C are considered (see K. Agabi "First whole atmosphere night-time seeing measurements at Dome C, Antarctica"). We also study the possible science reachable with such a demonstrator. Especially we evaluate that even such small aperture interferometer could allow the detection and low resolution spectroscopy of the most favourable pegaside planets.Comment: 6 pages, 5 figures, conferences SPIE, 0rlando, 200

Thermal tolerance, climatic variability and latitude

The greater latitudinal extents of occurrence of species towards higher latitudes has been attributed to the broadening of physiological tolerances with latitude as a result of increases in climatic variation. While there is some support for such patterns in climate, the physiological tolerances of species across large latitudinal gradients have seldom been assessed. Here we report findings for insects based on published upper and lower lethal temperature data. The upper thermal limits show little geographical variation. In contrast, the lower bounds of supercooling points and lower lethal temperatures do indeed decline with latitude. However, this is not the case for the upper bounds, leading to an increase in the variation in lower lethal limits with latitude. These results provide some support for the physiological tolerance assumption associated with Rapoport's rule, but highlight the need for coupled data on species tolerances and range size

The encapsulation of DNA molecules within biomimetic lipid nanocapsules

Most of DNA synthetic complexes result from the self-assembly of DNA molecules with cationic lipids or polymers in an aqueous controlled medium. However, injection of such self-assembled complexes in medium like blood that differ from that of their formulation leads to strong instability. Therefore, DNA vectors that have physico-chemical properties and structural organisation that will not be sensitive to a completely different medium in terms of ionic and protein composition are actively sought. To this end, the goal here was to discover and optimize a nanostructured system where DNA molecules would be encapsulated in nanocapsules consisting in an oily core and a shell covered by PEG stretches obtained through a nanoemulsion process in the absence of organic solvent. This encapsulation form of DNA molecules would prevent interactions with external hostile biological fluid. The results show the entrapment of lipoplexes into lipid nanocapsules, leading to the formation of neutral 110 nm-DNA nanocapsules. They were weakly removed by the immune system, displaying an increased blood half-life, and improved carcinoma cell transfection, in comparison to the parent lipoplexes. Our results demonstrate that the fabrication of nanocapsules encapsulating hydrophilic DNA in an oily core that meet criteria for blood injection is possible

Digestive and appendicular soft-parts, with behavioural implications, in a large Ordovician trilobite from the Fezouata Lagerstätte, Morocco

Trilobites were one of the most successful groups of marine arthropods during the Palaeozoic era, yet their soft-part anatomy is only known from a few exceptionally-preserved specimens found in a handful of localities from the Cambrian to the Devonian. This is because, even if the sclerotized appendages were not destroyed during early taphonomic stages, they are often overprinted by the three-dimensional, mineralised exoskeleton. Inferences about the ventral anatomy and behavioural activities of trilobites can also be derived from the ichnological record, which suggests that most Cruziana and Rusophycus trace fossils were possibly produced by the actions of trilobites. Three specimens of the asaphid trilobite Megistaspis (Ekeraspis) hammondi, have been discovered in the Lower Ordovician Fezouata Konservat-Lagerstätte of southern Morocco, preserving appendages and digestive tract. The digestive structures include a crop with digestive caeca, while the appendages display exopodal setae and slight heteropody (cephalic endopods larger and more spinose than thoracic and pygidial ones). The combination of these digestive structures and the heteropody has never been described together among trilobites, and the latter could assist in the understanding of the production of certain comb-like traces of the Cruziana rugosa group, which are extraordinarily abundant on the shallow marine shelves around Gondwana.This work has been supported by the Spanish Ministry of Economy and Competitiveness, project number CGL2012- 39471/BTE.Peer reviewe

Strong near-infrared emission in the sub-AU disk of the Herbig Ae star HD 163296: evidence of refractory dust?

This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this record.We present new long-baseline spectro-interferometric observations of the Herbig Ae star HD 163296 (MWC 275) obtained in the H and K bands with the AMBER instrument at the VLTI. The observations cover a range of spatial resolutions between ∼3 and ∼12 milliarcseconds, with a spectral resolution of ∼30. With a total of 1481 visibilities and 432 closure phases, they represent the most comprehensive (u, v) coverage achieved so far for a young star. The circumstellar material is resolved at the sub-AU spatial scale and closure phase measurements indicate a small but significant deviation from point-symmetry. We discuss the results assuming that the near-infrared excess in HD 163296 is dominated by the emission of a circumstellar disk. A successful fit to the spectral energy distribution, near-infrared visibilities and closure phases is found with a model in which a dominant contribution to the H and K band emission originates in an optically thin, smooth and point-symmetric region extending from about 0.1 to 0.45 AU. At a distance of 0.45 AU from the star, silicates condense, the disk becomes optically thick and develops a puffed-up rim, whose skewed emission can account for the non-zero closure phases. We discuss the source of the inner disk emission and tentatively exclude dense molecular gas as well as optically thin atomic or ionized gas as its possible origin. We propose instead that the smooth inner emission is produced by very refractory grains in a partially cleared region, extending to at least ∼0.5 AU. If so, we may be observing the disk of HD 163296 just before it reaches the transition disk phase. However, we note that the nature of the refractory grains or, in fact, even the possibility of any grain surviving at the very high temperatures we require (∼2100−2300 K at 0.1 AU from the star) is unclear and should be investigated further.We acknowledge fundings from CNRS and INAF (grant ASI-INAF I/016/07/0). This work was in part performed under contract with the Jet Propulsion Laboratory (JPL) funded by NASA through the Michelson Fellowship Progra

An overview of the mid-infrared spectro-interferometer MATISSE: science, concept, and current status

MATISSE is the second-generation mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This new interferometric instrument will allow significant advances by opening new avenues in various fundamental research fields: studying the planet-forming region of disks around young stellar objects, understanding the surface structures and mass loss phenomena affecting evolved stars, and probing the environments of black holes in active galactic nuclei. As a first breakthrough, MATISSE will enlarge the spectral domain of current optical interferometers by offering the L and M bands in addition to the N band. This will open a wide wavelength domain, ranging from 2.8 to 13 um, exploring angular scales as small as 3 mas (L band) / 10 mas (N band). As a second breakthrough, MATISSE will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. Moreover, MATISSE will offer a spectral resolution range from R ~ 30 to R ~ 5000. Here, we present one of the main science objectives, the study of protoplanetary disks, that has driven the instrument design and motivated several VLTI upgrades (GRA4MAT and NAOMI). We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performances. We also discuss the current status of the MATISSE instrument, which is entering its testing phase, and the foreseen schedule for the next two years that will lead to the first light at Paranal.Comment: SPIE Astronomical Telescopes and Instrumentation conference, June 2016, 11 pages, 6 Figure

HD 46375: seismic and spectropolarimetric analysis of a young Sun hosting a Saturn-like planet

HD 46375 is known to host a Saturn-like exoplanet orbiting at 0.04 AU from its host star. Stellar light reflected by the planet was tentatively identified in the 34-day CoRoT run acquired in October-November 2008. We constrain the properties of the magnetic field of HD 46375 based on spectropolarimetric observations with the NARVAL spectrograph at the Pic du Midi observatory. In addition, we use a high-resolution NARVAL flux spectrum to contrain the atmospheric parameters. With these constraints, we perform an asteroseismic analysis and modelling of HD 46375 using the frequencies extracted from the CoRoT light curve. We used Zeeman Doppler imaging to reconstruct the magnetic map of the stellar surface. In the spectroscopic analysis we fitted isolated lines using 1D LTE atmosphere models. This analysis was used to constrain the effective temperature, surface gravity, and chemical composition of the star. To extract information about the p-mode oscillations, we used a technique based on the envelope autocorrelation function (EACF). From the Zeeman Doppler imaging observations, we observe a magnetic field of ~5 gauss. From the spectral analysis, HD 46375 is inferred to be an unevolved K0 type star with high metallicity [Fe/H]=+0.39. Owing to the relative faintness of the star (m_hip=8.05), the signal-to-noise ratio is too low to identify individual modes. However, we measure the p-mode excess power and large separation Delta nu_0=153.0 +/- 0.7 muHz. We are able do constrain the fundamental parameters of the star thanks to spectrometric and seismic analyses. We conclude that HD 46375 is similar to a young version of Alpha-CenB. This work is of special interest because of its combination of exoplanetary science and asteroseismology, which are the subjects of the current Kepler mission and the proposed PLATO mission.Comment: Accepted in Astronomy & Astrophysics. 8 pages, 9 figure

Outcome after failure of allogeneic hematopoietic stem cell transplantation in children with acute leukemia: a study by the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire (SFGM-TC)

Allogeneic hematopoietic stem cell transplantation (SCT) contributes to improved outcome in childhood acute leukemia (AL). However, therapeutic options are poorly defined in case of post-transplantation relapse. We aimed to compare treatment strategies in 334 consecutive children with acute leukemia relapse or progression after SCT in a recent ten-year period. Data could be analyzed in 288 patients (157 ALL, 123 AML and 8 biphenotypic AL) with a median age of 8.16 years at transplantation. The median delay from first SCT to relapse or progression was 182 days. The treatment consisted in chemotherapy alone (n=108), chemotherapy followed by second SCT (n=70), supportive/palliative care (n=67), combination of chemotherapy and DLI (n=30), or isolated reinfusion of donor lymphocytes (DLI) (n=13). The median OS duration after relapse was 164 days and differed according to therapy: DLI after chemotherapy = 385 d, second allograft = 391d, chemotherapy = 174d, DLI alone = 140d, palliative care = 43d. A second SCT or a combination of chemotherapy and donor lymphocytes infusion yielded similar outcome (HR=0.85, p=0.53) unlike chemotherapy alone (HR 1.43 p=0.04), palliative care (HR=4.24, p<0.0001) or isolated DLI (HR=1,94, p<0.04). Despite limitations in this retrospective setting, strategies including immunointervention appear superior to other approaches, mostly in AML

Direct constraint on the distance of y2 Velorum from AMBER/VLTI observations

In this work, we present the first AMBER observations, of the Wolf-Rayet and O (WR+O) star binary system y2 Velorum. The AMBER instrument was used with the telescopes UT2, UT3, and UT4 on baselines ranging from 46m to 85m. It delivered spectrally dispersed visibilities, as well as differential and closure phases, with a resolution R = 1500 in the spectral band 1.95-2.17 micron. We interpret these data in the context of a binary system with unresolved components, neglecting in a first approximation the wind-wind collision zone flux contribution. We show that the AMBER observables result primarily from the contribution of the individual components of the WR+O binary system. We discuss several interpretations of the residuals, and speculate on the detection of an additional continuum component, originating from the free-free emission associated with the wind-wind collision zone (WWCZ), and contributing at most to the observed K-band flux at the 5% level. The expected absolute separation and position angle at the time of observations were 5.1&plusmn;0.9mas and 66&plusmn;15&deg; respectively. However, we infer a separation of 3.62+0.11-0.30 mas and a position angle of 73+9-11&deg;. Our analysis thus implies that the binary system lies at a distance of 368+38-13 pc, in agreement with recent spectrophotometric estimates, but significantly larger than the Hipparcos value of 258+41-31 pc