3,873 research outputs found
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
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Validation of the Spanish version of the Problem Areas in Diabetes (PAID-SP) Scale
This study aimed to assess the psychometric properties of the Spanish version of the Problem Areas in Diabetes (PAID-SP) Scale. Data were collected from patients with type 1 and type 2 diabetes. The findings suggested that the PAID-SP is a reliable and valid measure of diabetes-specific emotional problems
Phosphomannosylation and the functional analysis of the extended Candida albicans MNN4-like gene family
We thank Luz A. López-Ramírez (Universidad de Guanajuato) for technical assistance. This work was supported by Consejo Nacional de Ciencia y Tecnología (ref. CB2011/166860; PDCPN2014-247109, and FC 2015-02-834), Universidad de Guanajuato (ref. 000025/11; 0087/13; ref. 1025/2016; Convocatoria Institucional para Fortalecer la Excelencia Académica 2015; CIFOREA 89/2016), Programa de Mejoramiento de Profesorado (ref. UGTO-PTC-261), and Red Temática Glicociencia en Salud (CONACYT-México). NG acknowledges the Wellcome Trust (086827, 075470, 101873, and 200208) and MRC Centre for Medical Mycology for funding (N006364/1). KJ was supported by a research visitor grant to Aberdeen from China Scholarship Council (CSC No. 201406055024). The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fmicb.2017.02156/full#supplementary-materialPeer reviewedPublisher PD
P246 PREVALENCE AND VIRAL LOAD OF PARVOVIRUS B19, VARICELLA-ZOSTER VIRUS, AND HUMAN HERPESVIRUS-6 IN MESENCHYMAL STEM CELLS OF PATIENTS WITH OSTEOARTHRITIS
Unveiling the chemical fingerprint of phosphorus-rich stars I. In the infrared region of APOGEE-2
The origin of phosphorus, one of the essential elements for life on Earth, is
currently unknown. Prevalent models of Galactic chemical evolution (GCE)
underestimate the amount of P compared to observations. The recently discovered
P-rich ([P/Fe] > 1 dex) and metal-poor giants further challenge current
theories on stellar nucleosynthesis. Since the observed stars are low-mass
giants, our primary goal is to find clues on their progenitor. By increasing
the number of known P-rich stars, we aim to narrow down a reliable chemical
abundance pattern and to place robust constraints on the responsible
nucleosynthetic mechanism. In the long term, identifying the progenitor of the
P-rich stars may contribute to the search for the source of P in our Galaxy. We
performed a detailed chemical abundance analysis based on the H-band spectra
from APOGEE-2 (DR17). Employing the BACCHUS code, we measured the abundances of
13 elements in the sample, which is mainly composed of a recent collection of
Si-enhanced giants. We also analyzed the orbital motions and compared the
abundance results to possible nucleosynthetic formation scenarios, and also to
detailed GCE models. We enlarged the sample of confirmed P-rich stars from 16
to 78 giants, which represents the largest sample of P-rich stars to date.
Significant enhancements in O, Al, Si and Ce, as well as systematic
correlations among the elements, unveil the chemical fingerprint of the P-rich
stars. The high Mg and C+N found in some of the P-rich stars with respect to
P-normal stars is not confirmed over the full sample. Strikingly, the strong
over-abundance in the -element Si is accompanied by normal Ca and S
abundances. Our analysis of the orbital motion showed that the P-rich stars do
not belong to a specific sub-population. In addition, we confirm that the
majority of the sample stars are not part of binary systems.Comment: 29 pages, 18 figures, 8 tables, accepted for publication in Astronomy
& Astrophysic
Chemical and kinematical properties of BSSs and HB stars in NGC 6397
We used three sets of high-resolution spectra acquired with the multifiber
facility FLAMES at the Very Large Telescope of the European Southern
Observatory to investigate the chemical and kinematical properties of a sample
of 42 horizontal branch (HB) stars, 18 Blue Straggler Stars (BSSs) and 86 main
sequence turn-off and sub-giant branch stars in the nearby globular cluster NGC
6397. We measured rotational velocities and Fe, O and Mg abundances. All the
unevolved stars in our sample turn out to have low rotational velocites (v sin
i< 10\kms), while HB stars and BSSs show a broad distribution, with values
ranging from 0 to 70 \kms. For HB stars with T<10500 K there is a clear
temperature-oxygen anti-correlation, that can be understood if the star
position along the HB is mainly determined by the He content. The hottest BSSs
and HB stars (with temperatures T>8200 K and T> 10500 K, respectively) also
show significant deviations in their iron abundance with respect to the cluster
metallicity (as traced by the unevolved stars, [Fe/H]=-2.12). While similar
chemical patterns have been already observed in other hot HB stars, this is the
first evidence ever collected for BSSs. We interprete these abundance anomalies
as due to the metal radiative levitation, occurring in stars with shallow or no
convective envelopes
New groups of planetary nebulae with peculiar dust chemistry towards the Galactic bulge
We investigate Galactic bulge planetary nebulae without emission-line central
stars for which peculiar infrared spectra have been obtained with the Spitzer
Space Telescope, including the simultaneous signs of oxygen and carbon based
dust. Three separate sub-groups can be defined characterized by the different
chemical composition of the dust and the presence of crystalline and amorphous
silicates.
We find that the classification based on the dust properties is reflected in
the more general properties of these planetary nebulae. However, some observed
properties are difficult to relate to the common view of planetary nebulae. In
particular, it is challenging to interpret the peculiar gas chemical
composition of many analyzed objects in the standard picture of the evolution
of planetary nebulae progenitors.
We confirm that the dual-dust chemistry phenomenon is not limited to
planetary nebulae with emission-line central stars.Comment: 17 pages, 13 figure
A teacher training workshop to promote the use of the VISIR Remote Laboratory for electrical circuits teaching
The learning of Physics involves building up and using lab experiments. In turn, teachers must be trained in experimenting and using several resources that enable them to design valuable teaching strategies and learning activities. Thanks to Information and Communication Technologies (ICT), virtual and remote labs can provide a framework where physical experiments can be developed. Altough remote labs have been in use for over a decade now in several countries and levels of education, its use at secondary schools in Latin America has not been reported yet. The Virtual Instruments System in Reality (VISIR) is one of these remote labs, suitable to practice in the area of electrical circuits. This paper aims at describing how this remote lab was used in a training workshop for secondary school level teachers of Physics in Costa Rica.info:eu-repo/semantics/publishedVersio
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