Un péril jeune en bibliothèque ? Enquête sur le regard porté par les bibliothécaires sur les grands adolescents

Mémoire de fin d\u27étude du diplôme de conservateur, promotion 22 portant sur l\u27accueil des grands adolescents (15-18 ans) en bibliothèque

POTENTIAL OF ASTROGRAPHIC PLATES FOR STELLAR FLARE DETECTION

A set of four test regions covering a total celestial area of 520 deg2 at low galactic latitude is investigated on a set of 130 century-old astrographic plates. About 8% of the 2 × 105 stars with apparent B magnitude 10–14 and with total proper-motion component larger than 002 yr-1 show a significant flickering greater than 0.4 mag in B over a timescale shorter than 20 minutes. About 25% of these stellar flare candidates concern stars with B-V ~ 0.2 (spectral type A7). A procedure to select pre–main-sequence stellar candidates from the distance-limited sample of 16 × 103 disk dwarfs with detected flickering in B magnitude ≥0.4 is presented in view of a mass loss of 10-8 M☉ yr-1, derived from the analysis of the angular momentum distribution of stellar orbits. Follow-up UBV photoelectric photometry at the present epoch of 200 nearby stellar flares along the Vulpecula Rift shows an effect of reddening in B-V and of blueing in U-B for about 10% of the targets. The detection of optically thin or thick disks around the selected targets is suggested. The success rate in detecting optical flares in nearby stars of ~1.5 M☉ with as much as 5 × 10-6 M☉ dumped onto the central star during the past 100 years, from deep astrographic plates coupled with 1 m–class telescope is estimated to 10% with a kinematical bias that can be dealt with

A versatile and practical synthesis toward the development of novel HIV-1 integrase inhibitors

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Size matters but hunger prevails—begging and provisioning rules in blue tit families

It is commonly observed in many bird species that dependent offspring vigorously solicit for food transfers provided by their parents. However, the likelihood of receiving food does not only depend on the parental response, but also on the degree of sibling competition, at least in species where parents raise several offspring simultaneously. To date, little is known about whether and how individual offspring adjusts its begging strategy according to the entwined effects of need, state and competitive ability of itself and its siblings. We here manipulated the hunger levels of either the two heaviest or the two lightest blue tit (Cyanistes caeruleus) nestlings in a short-term food deprivation experiment. Our results showed that the lightest nestlings consistently begged more than the heaviest nestlings, an effect that was overruled by the tremendous increase in begging behaviour after food deprivation. Meanwhile, the amplified begging signals after food deprivation were the only cue for providing parents in their decision process. Furthermore, we observed flexible but state-independent begging behaviour in response to changes in sibling need. As opposed to our expectations, nestlings consistently increased their begging behaviour when confronted with food deprived siblings. Overall, our study highlights that individual begging primarily aims at increasing direct benefits, but nevertheless reflects the complexity of a young birds’ family life, in addition to aspects of intrinsic need and state

Localizing INTEGRAL Sources with Chandra: X-Ray and Multi-Wavelength Identifications and Energy Spectra

We report on Chandra observations of 18 hard X-ray (>20 keV) sources discovered with the INTEGRAL satellite near the Galactic plane. For 14 of the INTEGRAL sources, we have uncovered one or two potential Chandra counterparts per source. These provide soft X-ray (0.3-10 keV) spectra and sub-arcsecond localizations, which we use to identify counterparts at other wavelengths, providing information about the nature of each source. Despite the fact that all of the sources are within 5 degrees of the plane, four of the IGR sources are AGN (IGR J01545+6437, IGR J15391-5307, IGR J15415-5029, and IGR J21565+5948) and four others are likely AGN (IGR J03103+5706, IGR J09189-4418, IGR J16413-4046, and IGR J16560-4958) based on each of them having a strong IR excess and/or extended optical or near-IR emission. We compare the X-ray and near-IR fluxes of this group of sources to those of AGN selected by their 2-10 keV emission in previous studies and find that these IGR AGN are in the range of typical values. There is evidence in favor of four of the sources being Galactic (IGR J12489-6243, IGR J15293-5609, IGR J16173-5023, and IGR J16206-5253), but only IGR J15293-5609 is confirmed as a Galactic source as it has a unique Chandra counterpart and a parallax measurement from previous optical observations that puts its distance at 1.56+/-0.12 kpc. The 0.3-10 keV luminosity for this source is 1.4e32 erg/s, and its optical/IR spectral energy distribution is well described by a blackbody with a temperature of 4200-7000 K and a radius of 12.0-16.4 Rsun. These values suggest that IGR J15293-5609 is a symbiotic binary with an early K-type giant and a white dwarf accretor. We also obtained likely Chandra identifications for IGR J13402-6428 and IGR J15368-5102, but follow-up observations are required to constrain their source types.Comment: 17 pages, accepted by Ap

Dust properties along anomalous extinction sightlines. II. Studying extinction curves with dust models

The large majority of extinction sight lines in our Galaxy obey a simple relation depending on one parameter, the total-to-selective extinction coefficient, Rv. Different values of Rv are able to match the whole extinction curve through different environments so characterizing normal extinction curves. In this paper more than sixty curves with large ultraviolet deviations from their best-fit one parameter curve are analyzed. These curves are fitted with dust models to shed light into the properties of the grains, the processes affecting them, and their relations with the environmental characteristics. The extinction curve models are reckoned by following recent prescriptions on grain size distributions able to describe one parameter curves for Rv values from 3.1 to 5.5. Such models, here extended down to Rv=2.0, allow us to compare the resulting properties of our deviating curves with the same as normal curves in a self-consistent framework, and thus to recover the relative trends overcoming the modeling uncertainties. Such curves represent the larger and homogeneous sample of anomalous curves studied so far with dust models. Results show that the ultraviolet deviations are driven by a larger amount of small grains than predicted for lines of sight where extinction depends on one parameter only. Moreover, the dust-to-gas ratios of anomalous curves are lower than the same values for no deviating lines of sight. Shocks and grain-grain collisions should both destroy dust grains, so reducing the amount of the dust trapped into the grains, and modify the size distribution of the dust, so increasing the small-to-large grain size ratio. Therefore, the extinction properties derived should arise along sight lines where shocks and high velocity flows perturb the physical state of the interstellar medium living their signature on the dust properties. (Abridged version)Comment: 31 pages,12 figures; accepted for publication in A&