67 research outputs found
Recalibration of Pagel's method for HII regions considering the thermal structure, the ionization structure, and the depletion of O into dust grains
Using a sample of 28 HII regions from the literature with measured
temperature inhomogeneity parameter, t^2, we present a statistical correction
to the chemical abundances determined with the Te(4363/5007) method. We used
the t^2 values to correct the oxygen gaseous abundances and consider the oxygen
depletion into dust to calculate the total abundances for these objects. This
correction is used to obtain a new calibration of Pagel's strong-line method,
R_{23}, to determine oxygen abundances in HII regions. Our new calibration
simultaneously considers the temperature structure, the ionization structure,
and the fraction of oxygen depleted into dust grains. Previous calibrations in
the literature have included one or two of these factors; this is the first
time all three are taken into account. This recalibration conciliates the
systematic differences among the temperatures found from different methods. We
find that the total correction due to thermal inhomogeneities and dust
depletion amounts to an increase in the O/H ratio of HII regions by factors of
1.7 to 2.2 (or 0.22 to 0.35 dex). This result has important implications in
various areas of astrophysics such as the study of the higher end of the
initial mass function, the star formation rate, and the mass-metallicity
relation of galaxies, among others.Comment: 16 pages (preprint), 4 figures, 1 Table, accepted in ApJ
Carbon Abundances in Starburst Galaxies of the Local Universe
The cosmological origin of carbon, the fourth most abundant element in the
Universe, is not well known and matter of heavy debate. We investigate the
behavior of C/O to O/H in order to constrain the production mechanism of
carbon. We measured emission-line intensities in a spectral range from 1600 to
10000 \AA\ on Space Telescope Imaging Spectrograph (STIS) long-slit spectra of
18 starburst galaxies in the local Universe. We determined chemical abundances
through traditional nebular analysis and we used a Markov Chain Monte Carlo
(MCMC) method to determine where our carbon and oxygen abundances lie in the
parameter space. We conclude that our C and O abundance measurements are
sensible. We analyzed the behavior of our sample in the [C/O] vs. [O/H] diagram
with respect to other objects such as DLAs, neutral ISM measurements, and disk
and halo stars, finding that each type of object seems to be located in a
specific region of the diagram. Our sample shows a steeper C/O vs. O/H slope
with respect to other samples, suggesting that massive stars contribute more to
the production of C than N at higher metallicities, only for objects where
massive stars are numerous; otherwise intermediate-mass stars dominate the C
and N production.Comment: Accepted for publication in Ap
A classification of HII regions based on Oxygen and Helium lines: The cases of TOL2146-391 and TOL0357-3915
We present long slit spectrophotometry of two HII regions: TOL2146-391 and
TOL0357-3915. We performed a detailed analysis that involves abundance
determinations relaxing the assumption of homogeneous temperature. The
temperature inhomogeneities values, t^2, were obtained through two methods: (i)
comparing abundances from oxygen recombination lines to abundances from
collisionally excited lines and (ii) by using the line intensity ratios of a
set of HeI lines together with the HELIO10 program. We find that the HELIO10
program is a good alternative to obtain a t^2 value in photoionized regions
where recombination lines of heavy elements are not available. We have plotted
27 high and low metallicity HII regions in an oxygen degree of ionization
versus t^2 diagram; we find areas populated by HII regions and areas void of
them; the physical characteristics of each area are discussed. In addition, an
average t^2 value can be determined for the objects in each area. We propose to
use this value for the cases where a direct measurement of t^2 cannot be
determinedComment: 41 pages (preview), 5 figures. Accepted for publication in The
Astrophysical Journa
A Precision Treatment Model for Internet-Delivered Cognitive Behavioral Therapy for Anxiety and Depression among University Students:A Secondary Analysis of a Randomized Clinical Trial
Importance: Guided internet-delivered cognitive behavioral therapy (i-CBT) is a low-cost way to address high unmet need for anxiety and depression treatment. Scalability could be increased if some patients were helped as much by self-guided i-CBT as guided i-CBT. Objective: To develop an individualized treatment rule using machine learning methods for guided i-CBT vs self-guided i-CBT based on a rich set of baseline predictors. Design, Setting, and Participants: This prespecified secondary analysis of an assessor-blinded, multisite randomized clinical trial of guided i-CBT, self-guided i-CBT, and treatment as usual included students in Colombia and Mexico who were seeking treatment for anxiety (defined as a 7-item Generalized Anxiety Disorder [GAD-7] score of ≥10) and/or depression (defined as a 9-item Patient Health Questionnaire [PHQ-9] score of ≥10). Study recruitment was from March 1 to October 26, 2021. Initial data analysis was conducted from May 23 to October 26, 2022. Interventions: Participants were randomized to a culturally adapted transdiagnostic i-CBT that was guided (n = 445), self-guided (n = 439), or treatment as usual (n = 435). Main Outcomes and Measures: Remission of anxiety (GAD-7 scores of ≤4) and depression (PHQ-9 scores of ≤4) 3 months after baseline. Results: The study included 1319 participants (mean [SD] age, 21.4 [3.2] years; 1038 women [78.7%]; 725 participants [55.0%] came from Mexico). A total of 1210 participants (91.7%) had significantly higher mean (SE) probabilities of joint remission of anxiety and depression with guided i-CBT (51.8% [3.0%]) than with self-guided i-CBT (37.8% [3.0%]; P =.003) or treatment as usual (40.0% [2.7%]; P =.001). The remaining 109 participants (8.3%) had low mean (SE) probabilities of joint remission of anxiety and depression across all groups (guided i-CBT: 24.5% [9.1%]; P =.007; self-guided i-CBT: 25.4% [8.8%]; P =.004; treatment as usual: 31.0% [9.4%]; P =.001). All participants with baseline anxiety had nonsignificantly higher mean (SE) probabilities of anxiety remission with guided i-CBT (62.7% [5.9%]) than the other 2 groups (self-guided i-CBT: 50.2% [6.2%]; P =.14; treatment as usual: 53.0% [6.0%]; P =.25). A total of 841 of 1177 participants (71.5%) with baseline depression had significantly higher mean (SE) probabilities of depression remission with guided i-CBT (61.5% [3.6%]) than the other 2 groups (self-guided i-CBT: 44.3% [3.7%]; P =.001; treatment as usual: 41.8% [3.2%]; P <.001). The other 336 participants (28.5%) with baseline depression had nonsignificantly higher mean (SE) probabilities of depression remission with self-guided i-CBT (54.4% [6.0%]) than guided i-CBT (39.8% [5.4%]; P =.07). Conclusions and Relevance: Guided i-CBT yielded the highest probabilities of remission of anxiety and depression for most participants; however, these differences were nonsignificant for anxiety. Some participants had the highest probabilities of remission of depression with self-guided i-CBT. Information about this variation could be used to optimize allocation of guided and self-guided i-CBT in resource-constrained settings. Trial Registration: ClinicalTrials.gov Identifier: NCT04780542.</p
Spectroscopic Time-series Performance of JWST/NIRSpec from Commissioning Observations
We report on JWST commissioning observations of the transiting exoplanet
HAT-P-14 b, obtained using the Bright Object Time Series (BOTS) mode of the
NIRSpec instrument with the G395H/F290LP grating/filter combination
(m). While the data were used primarily to verify that the NIRSpec BOTS
mode is working as expected, and to enable it for general scientific use, they
yield a precise transmission spectrum which we find is featureless down to the
precision level of the instrument, consistent with expectations given
HAT-P-14~b's small scale-height and hence expected atmospheric features. The
exquisite quality and stability of the \emph{JWST/NIRSpec} transit spectrum --
almost devoid of any systematic effects -- allowed us to obtain median
uncertainties of 50-60 ppm in this wavelength range at a resolution of
in a single exposure, which is in excellent agreement with pre-flight
expectations and close to the (or at the) photon-noise limit for a ,
F-type star like HAT-P-14. These observations showcase the ability of
NIRSpec/BOTS to perform cutting-edge transiting exoplanet atmospheric science,
setting the stage for observations and discoveries to be made in Cycle 1 and
beyond.Comment: 16 pages, 14 figures; part of the PASP Focus Issue "JWST Time-Series
Observations: Commissioning Performance". Paper after the first round of
referee comments; inputs welcom
JWST-TST DREAMS: Quartz Clouds in the Atmosphere of WASP-17b
Clouds are prevalent in many of the exoplanet atmospheres that have been
observed to date. For transiting exoplanets, we know if clouds are present
because they mute spectral features and cause wavelength-dependent scattering.
While the exact composition of these clouds is largely unknown, this
information is vital to understanding the chemistry and energy budget of
planetary atmospheres. In this work, we observe one transit of the hot Jupiter
WASP-17b with JWST's MIRI LRS and generate a transmission spectrum from 5-12
m. These wavelengths allow us to probe absorption due to the
vibrational modes of various predicted cloud species. Our transmission spectrum
shows additional opacity centered at 8.6 m, and detailed atmospheric
modeling and retrievals identify this feature as SiO(s) (quartz) clouds.
The SiO(s) clouds model is preferred at 3.5-4.2 versus a cloud-free
model and at 2.6 versus a generic aerosol prescription. We find the
SiO(s) clouds are comprised of small m particles,
which extend to high altitudes in the atmosphere. The atmosphere also shows a
depletion of HO, a finding consistent with the formation of
high-temperature aerosols from oxygen-rich species. This work is part of a
series of studies by our JWST Telescope Scientist Team (JWST-TST), in which we
will use Guaranteed Time Observations to perform Deep Reconnaissance of
Exoplanet Atmospheres through Multi-instrument Spectroscopy (DREAMS).Comment: 19 pages, 7 figures, accepted for publication in ApJ
CIBERER : Spanish national network for research on rare diseases: A highly productive collaborative initiative
Altres ajuts: Instituto de Salud Carlos III (ISCIII); Ministerio de Ciencia e Innovación.CIBER (Center for Biomedical Network Research; Centro de Investigación Biomédica En Red) is a public national consortium created in 2006 under the umbrella of the Spanish National Institute of Health Carlos III (ISCIII). This innovative research structure comprises 11 different specific areas dedicated to the main public health priorities in the National Health System. CIBERER, the thematic area of CIBER focused on rare diseases (RDs) currently consists of 75 research groups belonging to universities, research centers, and hospitals of the entire country. CIBERER's mission is to be a center prioritizing and favoring collaboration and cooperation between biomedical and clinical research groups, with special emphasis on the aspects of genetic, molecular, biochemical, and cellular research of RDs. This research is the basis for providing new tools for the diagnosis and therapy of low-prevalence diseases, in line with the International Rare Diseases Research Consortium (IRDiRC) objectives, thus favoring translational research between the scientific environment of the laboratory and the clinical setting of health centers. In this article, we intend to review CIBERER's 15-year journey and summarize the main results obtained in terms of internationalization, scientific production, contributions toward the discovery of new therapies and novel genes associated to diseases, cooperation with patients' associations and many other topics related to RD research
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