8 research outputs found
The ACS LCID project. V. The Star Formation History of the Dwarf Galaxy \objectname[]{LGS-3}: Clues for Cosmic Reionization and Feedback
We present an analysis of the star formation history (SFH) of the
transition-type (dIrr/dSph) Local Group galaxy \objectname[]{LGS-3} (Pisces)
based on deep photometry obtained with the {\it Advanced Camera for Surveys}
onboard the {\it Hubble Space Telescope}. Our analysis shows that the SFH of
\objectname[]{LGS-3} is dominated by a main episode Gyr ago with a
duration of 1.4 Gyr which formed of the stars. Subsequently,
\objectname[]{LGS-3} continued forming stars until the present, although at a
much lower rate. The lack of early chemical enrichment is in contrast to that
observed in the isolated dSph galaxies of comparable luminosity, implying that
the dSphs were more massive and subjected to more tidal stripping.
We compare the SFH of \objectname[]{LGS-3} with expectations from
cosmological models. Most or all the star formation was produced in
\objectname[]{LGS-3} after the reionization epoch, assumed to be completed at
or Gyr ago. The total mass of the galaxy is estimated to
be between 2 and M, corresponding to circular velocities
between 28 km\ s to 36 km\ s. These values are close to but
somewhat above the limit of 30 km\ s below which the UV background is
expected to prevent any star formation after reionization. Feedback from SNe
associated with the initial episode of star formation (mechanical luminosity
from SNe erg s) is probably inadequate to
completely blow away the gas. However, the combined effects of SN feedback and
UV background heating might be expected to completely halt star formation at
the reionization epoch for the low mass of \objectname[]{LGS-3}; this suggests
that self-shielding is important to the early evolution of galaxies in this
mass range.Comment: accepted to be published at Ap
Cosmic CARNage I: on the calibration of galaxy formation models
We present a comparison of nine galaxy formation models, eight semi-analytical, and one halo occupation distribution model, run on the same underlying cold dark matter simulation (cosmological box of comoving width 125h−1 Mpc, with a dark-matter particle mass of 1.24 × 109h−1M) and the same merger trees. While their free parameters have been calibrated to the same observational data sets using two approaches, they nevertheless retain some ‘memory’ of any previous calibration that served as the starting point (especially for the manually tuned models). For the first calibration, models reproduce the observed z = 0 galaxy stellar mass function (SMF) within 3σ. The second calibration extended the observational data to include the z = 2 SMF alongside the z ∼ 0 star formation rate function, cold gas mass, and the black hole–bulge mass relation. Encapsulating the observed evolution of the SMF from z = 2 to 0 is found to be very hard within the context of the physics currently included in the models. We finally use our calibrated models to study the evolution of the stellar-to-halo mass (SHM) ratio. For all models, we find that the peak value of the SHM relation decreases with redshift. However, the trends seen for the evolution of the peak position as well as the mean scatter in the SHM relation are rather weak and strongly model dependent. Both the calibration data sets and model results are publicly available
Sclérose tubéreuse de Bourneville diagnostic antenatal et conseil génétique (à propos de quatre cas)
TOULOUSE3-BU Santé-Centrale (315552105) / SudocTOULOUSE3-BU Santé-Allées (315552109) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF
Breakthrough Hormographiella aspergillata Infections Arising in Neutropenic Patients Treated Empirically with Caspofungin
International audienceHormographiella aspergillata, a filamentous basidiomycete, has rarely been involved in human infections. We describe 2 febrile neutropenic patients who developed a severe pulmonary infection due to H. aspergillata while receiving empirical caspofungin therapy for presumed fungal pneumonia. After introduction of liposomal amphotericin B, one patient, who had neutrophil recovery, presented a favorable outcome, while the other, who remained neutropenic throughout the course of infection, died. Resistant fungi, including basidiomycetes, may emerge during empirical treatment with caspofungin in febrile neutropenic patients. A rapid switch to any other potent antifungal should be rapidly considered in case of failure of caspofungin in this setting