593 research outputs found
A Spitzer IRS Survey of NGC 1333: Insights into disk evolution from a very young cluster
We report on the {\lambda} = 5-36{\mu}m Spitzer Infrared Spectrograph spectra
of 79 young stellar objects in the very young nearby cluster NGC 1333. NGC
1333's youth enables the study of early protoplanetary disk properties, such as
the degree of settling as well as the formation of gaps and clearings. We
construct spectral energy distributions (SEDs) using our IRS data as well as
published photometry and classify our sample into SED classes. Using
"extinction-free" spectral indices, we determine whether the disk, envelope, or
photosphere dominates the spectrum. We analyze the dereddened spectra of
objects which show disk dominated emission using spectral indices and
properties of silicate features in order to study the vertical and radial
structure of protoplanetary disks in NGC 1333. At least nine objects in our
sample of NGC 1333 show signs of large (several AU) radial gaps or clearings in
their inner disk. Disks with radial gaps in NGC 1333 show more-nearly pristine
silicate dust than their radially continuous counterparts. We compare
properties of disks in NGC 1333 to those in three other well studied regions,
Taurus-Auriga, Ophiuchus and Chamaeleon I, and find no difference in their
degree of sedimentation and dust processing.Comment: 67 pages, 20 figures, accepted to The Astrophysical Journal
Supplement Serie
A Spitzer view of protoplanetary disks in the gamma Velorum cluster
We present new Spitzer Space Telescope observations of stars in the young ~5
Myr gamma Velorum stellar cluster. Combining optical and 2MASS photometry, we
have selected 579 stars as candidate members of the cluster. With the addition
of the Spitzer mid-infrared data, we have identified 5 debris disks around
A-type stars, and 5-6 debris disks around solar-type stars, indicating that the
strong radiation field in the cluster does not completely suppress the
production of planetesimals in the disks of cluster members. However, we find
some evidence that the frequency of circumstellar primordial disks is lower,
and the IR flux excesses are smaller than for disks around stellar populations
with similar ages. This could be evidence for a relatively fast dissipation of
circumstellar dust by the strong radiation field from the highest mass star(s)
in the cluster. Another possibility is that gamma Velorum stellar cluster is
slightly older than reported ages and the the low frequency of primordial disks
reflects the fast disk dissipation observed at ~5 Myr.Comment: Accepted for publication in the Astrophysical Journal: 32 pages; 11
Figure
Molecular Detection of Babesia spp. (Apicomplexa: Piroplasma) in Free-Ranging Canids and Mustelids From Southern Italy.
Babesiosis is an emerging tick-borne disease caused by apicomplexan parasites with widespread geographical distribution and various wildlife species as reservoir hosts. The aims of this study were to investigate the prevalence and assess the role of free-ranging canids and mustelids in the maintenance of Babesia spp. in southern Italy. PCR analysis of splenic samples targeting the 18S rRNA gene revealed the presence of Babesia spp. in 36 of 82 (43.9%) red foxes (Vulpes vulpes) including 29 (58%) from Campania region and seven (21.8%) from Calabria region, in seven of 13 (53.8%) Eurasian badgers (Meles meles), and in one of 13 (7.7%) gray wolves (Canis lupus). Samples from other host species including 9 Eurasian otters (Lutra lutra), 1 stone marten (Martes foina), 1 least weasel (Mustela nivalis), and 1 European polecat (Mustela putorius) tested Babesia spp. negative. Sequence analysis of the 18S rRNA gene demonstrated the presence of B. vulpes in the red fox and two sequence types of badger-associated Babesia spp. in the Eurasian badger. The Babesia sp. sequence detected in the gray wolf was identical to a badger-associated Babesia sp. This study shows that the number of Babesia spp. infecting free-ranging carnivores in Italy is higher than currently believed, and suggests that these hosts may play an important role in the maintenance of the sylvatic cycle of these parasites. It is the first report of badger-associated Babesia spp. in Italy and in a gray wolf
Discovery of the heavily obscured supernova 2002cv
On the 13th of May 2002, supernova 2002cv was discovered using a
near-infrared camera working at the AZT-24 1.1m telescope at Campo Imperatore
(AQ-Italy). After the infrared detection a simultaneous photometric follow-up
was started at optical wavelengths. The preliminary results confirm a heavily
obscured object with a V-K color not lower than 6 magnitudes, making SN 2002cv
the most reddened supernova ever observed. This finding, along with the recent
discovery of another obscured supernova, suggests a critical revision of the
rates known to date. The estimate of the visual extinction and the light curves
are provided here. These latter indicate that our SN 2002cv observations are
the earliest available for a type-Ia supernova at IR wavelengths.Comment: 4 page
Altered miR-193a-5p expression in children with cow's milk allergy
Cow's milk allergy (CMA) is one of the most common food allergies in children. Epigenetic mechanisms have been suggested to play a role in CMA pathogenesis. We shown that DNA methylation of Th1/Th2 cytokine genes and FoxP3 affects CMA disease course. Preliminary evidence suggest that also the miRNome could be implicated in the pathogenesis of allergy. Main study outcome was to comparatively evaluate miRNome in children with CMA and in healthy controls
Precision measurement of the transition strength to the 2 state of C
The form factor of the electromagnetic excitation of C to its 2
state was measured at extremely low momentum transfers in an electron
scattering experiment at the S-DALINAC. A combined analysis with the world form
factor data results in a reduced transition strength efm with an accuracy improved to 2.5\%. In-Medium-No
Core Shell Model results with interactions derived from chiral effective field
theory are capable to reproduce the result. A quadrupole moment efm can be extracted from the strict correlation with the
strength emerging in the calculations.Comment: 6 pages, 6 figures, submitted to Phys. Rev.
Evolution of the dipole polarizability in the stable tin isotope chain
The dipole polarizability of stable even-mass tin isotopes
112,114,116,118,120,124 was extracted from inelastic proton scattering
experiments at 295 MeV under very forward angles performed at RCNP. Predictions
from energy density functionals cannot account for the present data and the
polarizability of 208Pb simultaneously. The evolution of the polarizabilities
in neighboring isotopes indicates a kink at 120Sn while all model results show
a nearly linear increase with mass number after inclusion of pairing
corrections.Comment: 10 pages, 6 figures, submitted to Phys. Lett.
The Rapid Outbursting Star GM Cep: An EX-or in Tr 37?
We present optical, IR and millimeter observations of the solar-type star
13-277, also known as GM Cep, in the 4 Myr-old cluster Tr 37. GM Cep
experiences rapid magnitude variations of more than 2 mag at optical
wavelengths. We explore the causes of the variability, which seem to be
dominated by strong increases in the accretion, being similar to EX-or
episodes. The star shows high, variable accretion rates (up to ~10
Msun/yr), signs of powerful winds, and it is a very fast rotator (Vsini~43
km/s). Its strong mid-IR excesses reveal a very flared disk and/or a remnant
envelope, most likely out of hydrostatic equilibrium. The 1.3 millimeter fluxes
suggest a relatively massive disk (Mdisk~0.1 Msun). Nevertheless, the
millimeter mass is not enough to sustain increased accretion episodes over
large timescales, unless the mass is underestimated due to significant grain
growth. We finally explore the possibility of GM Cep having a binary companion,
which could trigger disk instabilities producing the enhanced accretion
episodes.Comment: 43 pages, including 10 figures, ApJ in pres
Comparison of insulin glargine and liraglutide added to oral agents in patients with poorly controlled type 2 diabetes
Peer reviewe
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