Examinando por Autor "Vargas, C."

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    Clinical and organizational framework of repurposing pediatric intensive care unit to adult critical care in a resource-limited setting: Lessons from the response of an urban general hospital to the COVID-19 pandemic
    (W.B. Saunders, 2021-12) Díaz, F.; Kehr, J.; Cores, C.; Rubilar, P.; Medina, T.; Vargas, C.; Cruces, P.
    We aim to describe the action plan and clinical results of a COVID-19 unit for adult patient care in units intended for critically ill children, proposing a clinical/administrative framework. Methods: We reviewed the preparedness of the PICU team before the surge of cases of COVID-19 and the organizational/administrative issues to increase critical beds in a six-bed PICU allocated to adult critical care in a government-funded general hospital in Latin America. We analyzed the prospectively collected administrative/clinical data of severe COVID-19 cases admitted to PICU during the peak of the first wave of the pandemic. Results: We describe a 6-step preparedness plan: recruitment and education, admission criteria, children diversion, team hierarchy, and general and respiratory equipment. The 6-bed PICU was allocated to adult care for 20 weeks, progressively increasing capacity to a 23-bed dedicated COVID-19 unit managed by the PICU team. A six-block bed organizational units were implemented, and personnel increased from 40 to 125 healthcare workers in 24 h shifts. COVID-19 incidence in personnel was 0.5/1000 workdays. One hundred thirty-six patients were admitted, median age 59 (51,65) years old, 68% were male, and 63% had P/F ≤ 100. In addition, 48% received mechanical ventilation, the median length of stay was 7 (3,17), and in-hospital mortality was 15%. Conclusions: We propose an organizational framework for the role of PICU in the hospital action plan to increase adult critical beds. The cohort of patients admitted to a PICU repurposed as a COVID-19 ICU had good outcomes. These data are valuable to plan coordinated actions of the healthcare system for future scenarios.
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    Intrinsic metallicity variation in the intermediate mass type ii globular cluster ngc 1261
    (Oxford University Press, 2021-10-01) Muñoz, C.; Geisler, D.; Villanova, S.; Sarajedini, Ata; Frelijj, H.; Vargas, C.; Monaco L.; O'connell J.
    Globular Clusters (GCs) are now well known to almost universally show multiple populations (MPs). The HST UV Legacy Survey of a large number of Galactic GCs in UV filters optimized to explore MPs finds that a small fraction of GCs, termed Type II, also display more complex, anomalous behaviour. Several well-studied Type II GCs show intrinsic Fe abundance variations, suggesting that the other, less well-studied, Type II GCs should also exhibit similar behaviour. Our aim is to perform the first detailed metallicity analysis of NGC 1261, an intermediate mass Type II GC, in order to determine if this object shows an intrinsic Fe variation. We determined the Fe abundance in eight red giant members using Magellan-MIKE and UVES-FLAMES high-resolution, high S/N spectroscopy. The full range of [Fe/H] for the entire sample from the spectra is from -1.05 to -1.43 dex with an observed spread σobs = 0.133 dex. Compared with the total internal error of σtot = 0.06, this indicates a significant intrinsic metallicity spread of σint = 0.119 dex. We found a very similar variation in [Fe/H] using an independent method to derive the atmospheric parameters based on near-IR photometry. More importantly, the mean metallicity of the five presumed normal metallicity stars is -1.37 ± 0.02, while that of the three presumed anomalous/high metallicity stars is -1.18 ± 0.09. This difference is significant at the ∼2.4σ level. We find indications from existing data of other Type II GCs that several of them presumed to have real metallicity spreads may in fact possess none. The minimum mass required for a GC to acquire an intrinsic Fe spread appears to be ∼105M⊙. We find no strong correlation between mass and metallicity variation for Type II GCs. The metallicity spread is also independent of the fraction of anomalous stars within the Type II GCs and of GC origin. © 2021 The Author(s).
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    Investigating a predicted metallicity [Fe/H] variation in the Type II Globular Cluster NGC 362
    (Oxford University Press, 2022-09-01) Vargas, C.; Villanova, S.; Geisler, D.; Muñoz, C.; Monaco, L.; O'Connell, J.; Sarajedini, Ata
    NGC 362 is a non-common Type II Galactic globular cluster, showing a complex pseudo two-colour diagram or 'chromosome map'. The clear separation of its stellar populations in the colour-magnitude diagram and the distribution of the giant stars in the chromosome map strongly suggests that NGC 362 could host stars with both cluster-nominal, as well as enhanced heavy-element abundances, and one of them could be iron. However, despite previous spectroscopic observations of NGC 362, no such iron variation has been detected. Our main goal is to confirm or disprove this result by searching for any internal variation of [Fe/H], which would give us insight into the formation and evolution of this interesting globular cluster. In this paper, we present the abundance analysis for a sample of 11 red giant branch members based on high-resolution and high S/N spectra obtained with the MIKE echelle spectrograph mounted at the Magellan-Clay telescope. HST and GAIA photometry and astrometry has been used to determine atmospheric parameters and membership. We obtained Teff, log(g), and vt for our target stars and measured the mean iron content of the sample and its dispersion with three different methods, which lead to [Fe/H]1 =-1.10±0.02, [Fe/H]2 =-1.09 ±0.01, and [Fe/H]3 =-1.10 ±0.01, while the internal dispersion turned out to be σ[ Fe/H ]1 = 0.06 ±0.01, σ[Fe/H ]2 = 0.03 ±0.01, and σ[ Fe/H ]3 = 0.05 ±0.01, respectively. The error analysis gives an internal dispersion due to observational error of 0.05 dex. Comparing the observed dispersion with the internal errors, we conclude that NGC 362 does not show any trace of an internal iron spread. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
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    Ocean Acidification Disrupts Prey Responses to Predator Cues but Not Net Prey Shell Growth in Concholepas concholepas (loco)
    (Public Library of Science, 2013-07) Manríquez, P.; Jara, M.; Mardone, M.; Navarro, J.; Torres, R.; Lardies, M.; Vargas, C.; Duarte, C.; Widdicombe, S.; Salisbury, J.; Lagos, N.
    Background:Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation.Methodology/Principal Findings:The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716±12 and 1036±14 μatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 μatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab.Conclusions and Significance:These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.