3,590 research outputs found
Low mass star formation and subclustering in the HII regions RCW 32, 33 and 27 of the Vela Molecular Ridge. A photometric diagnostics to identify M-type stars
Most stars born in clusters and recent results suggest that star formation
(SF) preferentially occurs in subclusters. Studying the morphology and SF
history of young clusters is crucial to understanding early SF. We identify the
embedded clusters of young stellar objects (YSOs) down to M stars, in the HII
regions RCW33, RCW32 and RCW27 of the Vela Molecular Ridge. Our aim is to
characterise their properties, such as morphology and extent of the clusters in
the three HII regions, derive stellar ages and the connection of the SF history
with the environment. Through public photometric surveys such as Gaia, VPHAS,
2MASS and Spitzer/GLIMPSE, we identify YSOs with IR, Halpha and UV excesses, as
signature of circumstellar disks and accretion. In addition, we implement a
method to distinguish M dwarfs and giants, by comparing the reddening derived
in several optical/IR color-color diagrams, assuming suitable theoretical
models. Since this diagnostic is sensitive to stellar gravity, the procedure
allows us to identify pre-main sequence stars. We find a large population of
YSOs showing signatures of circumstellar disks with or without accretion. In
addition, with the new technique of M-type star selection, we find a rich
population of young M stars with a spatial distribution strongly correlated to
the more massive population. We find evidence of three young clusters, with
different morphology. In addition, we identify field stars falling in the same
region, by securely classifying them as giants and foreground MS stars. We
identify the embedded population of YSOs, down to about 0.1 Msun, associated
with the HII regions RCW33, RCW32 and RCW27 and the clusters Vela T2, Cr197 and
Vela T1, respectively, showing very different morphologies. Our results suggest
a decreasing SF rate in Vela T2 and triggered SF in Cr197 and Vela T1.Comment: Accepted for publication in A&A; 20 pages, 22 figures, 6 table
A new eclipsing binary system with a pulsating component detected by CoRoT
We report the discovery of CoRoT 102980178 (R.A.= 06:50:12.10, Dec.=
-02:41:21.8, J2000) an Algol-type eclipsing binary system with a pulsating
component (oEA). It was identified using a publicly available 55 day long
monochromatic lightcurve from the CoRoT initial run dataset (exoplanet field).
Eleven consecutive 1.26m deep total primary and the equal number of 0.25m deep
secondary eclipses (at phase 0.50) were observed. The following light elements
for the primary eclipse were derived: HJD_MinI= 2454139.0680 + 5.0548d x E. The
lightcurve modeling leads to a semidetached configuration with the photometric
mass ratio q=0.2 and orbital inclination i=85 deg. The out-of-eclipse
lightcurve shows ellipsoidal variability and positive O'Connell effect as well
as clear 0.01m pulsations with the dominating frequency of 2.75 c/d. The
pulsations disappear during the primary eclipses, which indicates the primary
(more massive) component to be the pulsating star. Careful frequency analysis
reveals the second independent pulsation frequency of 0.21 c/d and numerous
combinations of these frequencies with the binary orbital frequency and its
harmonics. On the basis of the CoRoT lightcurve and ground based multicolor
photometry, we favor classification of the pulsating component as a gamma
Doradus type variable, however, classification as an SPB star cannot be
excluded.Comment: 16 pages, 7 figures, 3 tables, accepted to Communications in
Asteroseismolog
Aportes al manejo integrado de la cuenca hÃdrica en Baldes del Rosario (San Juan) : una experiencia de aprendizaje-servicio
La experiencia es parte de la estrategia docente que se viene desarrollando desde el año 2000 en la cátedra de Manejo de Suelos y Recursos HÃdricos (plan 1996) y Manejo Integrado de Cuencas HÃdricas (plan 2012), perteneciente al quinto año de la Licenciatura en BiologÃa de la UNSJ. La experiencia está coordinada con la asignatura Manejo de Bosques y Pasturas Naturales, y se llevó a cabo en los ciclos lectivos 2016 y 2017 en Baldes del Rosario, localidad del Departamento Valle Fértil. Los destinatarios fueron tanto la población visitada como los estudiantes, ya que ambos se beneficiaron con el proyecto; el objetivo es la adquisición de aprendizajes, a la vez que el mejoramiento de las condiciones de vida de la comunidad. Se realizó un trabajo previo de gabinete y un trabajo de campo, caracterizando todos los componentes de la cuenca hÃdrica. Luego se realizó una devolución de los resultados a la comunidad, apuntando a la toma de decisiones de manejo de manera participativa.Fil: Gaviorno, M.
Universidad Nacional de San JuanFil: Salvioli, L.
Universidad Nacional de San JuanFil: Damiani, O.
Universidad Nacional de San Jua
Variability of the nighttime OH layer and mesospheric ozone at high latitudes during northern winter: influence of meteorology
Abstract. Analyses of OH zonal means, recorded at boreal high latitudes by the Aura Microwave Limb Sounder (MLS) in winters of 2005–2009, have shown medium- (weeks) and short- (days) term variability of the nighttime OH layer. Because of the exceptional descent of air from the mesosphere-lower thermosphere (MLT) region, medium-term variability occurred during February 2006 and February/March 2009. The layer normally situated at about 82 km descended by about 5–7 km, and its density increased to more than twice January values. In these periods and location the abundance of the lowered OH layer is comparable to the OH values induced by Solar Energetic Particle (SEP) forcing (e.g., SEP events of January 2005) at the same altitudes. In both years, the descent of the OH layer was coupled with increased mesospheric temperatures, elevated carbon monoxide and an almost complete disappearance of ozone at the altitude of the descended layer (which was not observed in other years). Moreover, under these exceptional atmospheric conditions, the third ozone peak, normally at about 72 km, is shown to descend about 5 km to lower altitude and increase in magnitude, with maximum values recorded during February 2009. Short-term variability occurred during Sudden Stratospheric Warming (SSW) events, in particular in January 2006, February 2008 and January 2009, when dynamics led to a smaller abundance of the OH layer at its typical altitude. During these periods, there was an upward displacement of the OH layer coupled to changes in ozone and carbon monoxide. These perturbations were the strongest during the SSW of January 2009; coincident upper mesospheric temperatures were the lowest recorded over the late winters of 2005–2009. Finally, the series of SSW events that occurred in late January/February 2008 induced noticeable short-term variability in ozone at altitudes of both the ozone minimum and the third ozone peak. These phenomena, confined inside the polar vortex, are an additional tool that can be used to investigate mesospheric vortex dynamics
Correlation between the spatial distribution of circumstellar disks and massive stars in the young open cluster NGC 6611. II: Cluster members selected with Spitzer/IRAC
Context: the observations of the proplyds in the Orion Nebula Cluster,
showing clear evidence of ongoing photoevaporation, have provided a clear proof
about the role of the externally induced photoevaporation in the evolution of
circumstellar disks. NGC 6611 is an open cluster suitable to study disk
photoevaporation, thanks to its large population of massive members and of
stars with disk. In a previous work, we obtained evidence of the influence of
the strong UV field generated by the massive cluster members on the evolution
of disks around low-mass Pre-Main Sequence members. That work was based on a
multi-band BVIJHK and X-ray catalog purposely compiled to select the cluster
members with and without disk. Aims: in this paper we complete the list of
candidate cluster members, using data at longer wavelengths obtained with
Spitzer/IRAC, and we revisit the issue of the effects of UV radiation on the
evolution of disks in NGC 6611. Methods: we select the candidate members with
disks of NGC 6611, in a field of view of 33'x34' centered on the cluster, using
IRAC color-color diagrams and suitable reddening-free color indices. Besides,
using the X-ray data to select Class III cluster members, we estimate the disks
frequency vs. the intensity of the incident radiation emitted by massive
members. Results: we identify 458 candidate members with circumstellar disks,
among which 146 had not been revealed in our previous work. Comparing of the
various color indices we used to select the cluster members with disk, we claim
that they detect the excesses due to the emission of the same physical region
of the disk: the inner rim at the dust sublimation radius. Our new results
confirm that UV radiation from massive stars affects the evolution of nearby
circumstellar disks.Comment: Accepted for publication at Astronomy & Astrophysic
Machine-Readable Privacy Certificates for Services
Privacy-aware processing of personal data on the web of services requires
managing a number of issues arising both from the technical and the legal
domain. Several approaches have been proposed to matching privacy requirements
(on the clients side) and privacy guarantees (on the service provider side).
Still, the assurance of effective data protection (when possible) relies on
substantial human effort and exposes organizations to significant
(non-)compliance risks. In this paper we put forward the idea that a privacy
certification scheme producing and managing machine-readable artifacts in the
form of privacy certificates can play an important role towards the solution of
this problem. Digital privacy certificates represent the reasons why a privacy
property holds for a service and describe the privacy measures supporting it.
Also, privacy certificates can be used to automatically select services whose
certificates match the client policies (privacy requirements).
Our proposal relies on an evolution of the conceptual model developed in the
Assert4Soa project and on a certificate format specifically tailored to
represent privacy properties. To validate our approach, we present a worked-out
instance showing how privacy property Retention-based unlinkability can be
certified for a banking financial service.Comment: 20 pages, 6 figure
Interprofessional Collaboration and Diabetes Management in Primary Care: A Systematic Review and Meta-Analysis of Patient-Reported Outcomes
The global spread of diabetes poses serious threats to public health requiring a patient-centered approach based both on interprofessional collaboration (IPC) given by the cooperation of several different health professionals, and patients’ perspective through the assessment of Patient-Reported Outcomes (PROs). The aim of the present study is to evaluate the impact of interprofessional collaboration interventions, for the management of type 2 diabetes in primary care settings, through PROs. A systematic review and meta-analysis was conducted querying the PubMed, Scopus and Embase databases. Out of the 1961 papers initially retrieved, 19 met the inclusion criteria. Interprofessional collaboration is significantly associated with an increase in both patient’s satisfaction (SMD 0.32 95% CI 0.05–0.59) and in the mental well-being component of the HRQoL (SMD 0.18; 95% CI 0.06–0.30), and there was also promising evidence supporting the association between an interprofessional approach and an increase in self-care and in generic and specific quality-of-life. No statistical differences were found, supporting the positive impact on IPC interventions on the physical component of the HRQoL, depression, emotional distress, and self-efficacy. In conclusion, the effect of IPC impacts positively on the few areas assessed by PROMs. Policymakers should promote the widespread adoption of a collaborative approach as well as to endorse an active engagement of patients across the whole process of care
The Gaia-ESO Survey: dynamics of ionized and neutral gas in the Lagoon nebula (M8)
We present a spectroscopic study of the dynamics of the ionized and neutral
gas throughout the Lagoon nebula (M8), using VLT/FLAMES data from the Gaia-ESO
Survey. We explore the connections between the nebular gas and the stellar
population of the associated star cluster NGC6530. We characterize through
spectral fitting emission lines of H-alpha, [N II] and [S II] doublets, [O
III], and absorption lines of sodium D doublet, using data from the
FLAMES/Giraffe and UVES spectrographs, on more than 1000 sightlines towards the
entire face of the Lagoon nebula. Gas temperatures are derived from line-width
comparisons, densities from the [S II] doublet ratio, and ionization parameter
from H-alpha/[N II] ratio. Although doubly-peaked emission profiles are rarely
found, line asymmetries often imply multiple velocity components along the line
of sight. This is especially true for the sodium absorption, and for the [O
III] lines. Spatial maps for density and ionization are derived, and compared
to other known properties of the nebula and of its massive stars 9 Sgr,
Herschel 36 and HD 165052 which are confirmed to provide most of the ionizing
flux. The detailed velocity fields across the nebula show several expanding
shells, related to the cluster NGC6530, the O stars 9 Sgr and Herschel 36, and
the massive protostar M8East-IR. The origins of kinematical expansion and
ionization of the NGC6530 shell appear to be different. We are able to put
constrains on the line-of-sight (relative or absolute) distances between some
of these objects and the molecular cloud. The large obscuring band running
through the middle of the nebula is being compressed by both sides, which might
explain its enhanced density. We also find an unexplained large-scale velocity
gradient across the entire nebula. At larger distances, the transition from
ionized to neutral gas is studied using the sodium lines.Comment: 26 pages, 31 figures, accepted on Astronomy and Astrophysics journa
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