24 research outputs found
Recommended from our members
The ACS Survey Of Galactic Globular Clusters. VI. NGC 6366: A Heavily Stripped Galactic Globular Cluster
We have used observations obtained as part of the Hubble Space Telescope/ACS Survey of Galactic globular clusters (GCs) to construct a color-magnitude diagram for the bulge cluster, NGC 6366. The luminosity function derived from those data extends to M(F606W) similar to 9, or masses of similar to 0.3 M(circle dot). Unlike most GCs, the mass function peaks near the main-sequence turnoff with significantly fewer low-mass stars even after correction for completeness and mass segregation. Using a multimass King model, we extrapolate the global cluster behavior and find the global mass function to be poorly matched by a power law, with a particular deficit of stars with masses between 0.5 and 0.7 M(circle dot). We briefly discuss this interesting anomaly within the context of tidal stripping.NASA GO-10775, 5-26555Space Telescope Science InstituteInstituto de Astrofisica de Canarias P3-94Ministry of Education and Science of the Kingdom of Spain AYA-2008-67913Astronom
The ACS survey of galactic globular clusters. XI. The three-dimensional orientation of the Sagittarius dwarf spheroidal galaxy and its globular clusters
We use observations from the Hubble Space Telescope Advanced Camera for Surveys (HST/ACS) study of Galactic globular clusters to investigate the spatial distribution of the inner regions of the disrupting Sagittarius dwarf spheroidal galaxy (Sgr). We combine previously published analyses of four Sgr member clusters located near or in the Sgr core (M54, Arp 2, Terzan 7, and Terzan 8) with a new analysis of diffuse Sgr material identified in the background of five low-latitude Galactic bulge clusters (NGC 6624, 6637, 6652, 6681, and 6809) observed as part of the ACS survey. By comparing the bulge cluster color-magnitude diagrams to our previous analysis of the M54/Sgr core, we estimate distances to these background features. The combined data from four Sgr member clusters and five Sgr background features provide nine independent measures of the Sgr distance and, as a group, provide uniformly measured and calibrated probes of different parts of the inner regions of Sgr spanning 20° over the face of the disrupting dwarf. This allows us, for the first time, to constrain the three-dimensional orientation of Sgr's disrupting core and globular cluster system and compare that orientation to the predictions of an N-body model of tidal disruption. The density and distance of Sgr debris are consistent with models that favor a relatively high Sgr core mass and a slightly greater distance (28-30kpc, with a mean of 29.4kpc). Our analysis also suggests that M54 is in the foreground of Sgr by ⌠2 kpc, projected on the center of the Sgr dSph. While this would imply a remarkable alignment of the cluster and the Sgr nucleus along the line of sight, we cannot identify any systematic effect in our analysis that would falsely create the measured 2kpc separation. Finally, we find that the cluster Terzan 7 has the most discrepant distance (25kpc) among the four Sgr core clusters, which may suggest a different dynamical history than the other Sgr core clusters
The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters without PreviousHubble Space Telescope Photometry
We present the first results of a large Advanced Camera for Surveys (ACS) survey of Galactic globular clusters. This Hubble Space Telescope (HST) Treasury project is designed to obtain photometry with S/N (signal-to-noise ratio) 10 for main-sequence stars with masses 0.2 Mâ in a sample of globulars using the ACS Wide Field Channel. Here we focus on clusters without previous HST imaging data. These include NGC 5466, NGC 6779, NGC 5053, NGC 6144, Palomar 2, E3, LyngĂ„ 7, Palomar 1, and NGC 6366. Our color-magnitude diagrams (CMDs) extend reliably from the horizontal branch to as much as 7 mag fainter than the main-sequence turnoff and represent the deepest CMDs published to date for these clusters. Using fiducial sequences for three standard clusters (M92, NGC 6752, and 47 Tuc) with well-known metallicities and distances, we perform main-sequence fitting on the target clusters in order to obtain estimates of their distances and reddenings. These comparisons, along with fitting the cluster main sequences to theoretical isochrones, yield ages for the target clusters. We find that the majority of the clusters have ages that are consistent with the standard clusters at their metallicities. The exceptions are E3, which appears ~2 Gyr younger than 47 Tuc, and Pal 1, which could be as much as 8 Gyr younger than 47 Tuc
FLAMINGOS-2: The Facility Near-Infrared Wide-field Imager & Multi-Object Spectrograph for Gemini
We report on the design and status of the FLAMINGOS-2 instrument - a
fully-cryogenic facility near-infrared imager and multi-object spectrograph for
the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical
optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular
field-of-view on a 2048x2048-pixel HAWAII-2 0.9-2.4 mm detector array. A
slit/decker wheel mechanism allows the selection of up to 9 multi-object
laser-machined plates or 3 long slits for spectroscopy over a 6x2-arcminute
field of view, and selectable grisms provide resolutions from 1300 to
3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also
compatible with the Gemini Multi-Conjugate Adaptive Optics system, providing
multi-object spectroscopic capabilities over a 3x1-arcminute field with high
spatial resolution (0.09-arcsec/pixel). We review the designs of optical,
mechanical, electronics, software, and On-Instrument WaveFront Sensor
subsystems. We also present the current status of the project, currently in
final testing in mid-2006.Comment: Submitted to SPIE Astronomical Telescopes & Instrumentation; 12
pages, incl. color figure
2 nd Brazilian Consensus on Chagas Disease, 2015
Abstract Chagas disease is a neglected chronic condition with a high burden of morbidity and mortality. It has considerable psychological, social, and economic impacts. The disease represents a significant public health issue in Brazil, with different regional patterns. This document presents the evidence that resulted in the Brazilian Consensus on Chagas Disease. The objective was to review and standardize strategies for diagnosis, treatment, prevention, and control of Chagas disease in the country, based on the available scientific evidence. The consensus is based on the articulation and strategic contribution of renowned Brazilian experts with knowledge and experience on various aspects of the disease. It is the result of a close collaboration between the Brazilian Society of Tropical Medicine and the Ministry of Health. It is hoped that this document will strengthen the development of integrated actions against Chagas disease in the country, focusing on epidemiology, management, comprehensive care (including families and communities), communication, information, education, and research
Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19
IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19.
Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19.
DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 nonâcritically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022).
INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (nâ=â257), ARB (nâ=â248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; nâ=â10), or no RAS inhibitor (control; nâ=â264) for up to 10 days.
MAIN OUTCOMES AND MEASURES The primary outcome was organ supportâfree days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes.
RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ supportâfree days among critically ill patients was 10 (â1 to 16) in the ACE inhibitor group (nâ=â231), 8 (â1 to 17) in the ARB group (nâ=â217), and 12 (0 to 17) in the control group (nâ=â231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ supportâfree days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively).
CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes.
TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570
Cu-SSZ-39, an active and hydrothermally stable catalyst for the selective catalytic reduction of NOx
[EN] A Cu-exchanged SSZ-39 zeolite has been synthesized and tested for the selective catalytic reduction (SCR) of NOx. This material shows an excellent catalytic activity, and most importantly, an
extraordinary hydrothermal stabilityThis work has been supported by Haldor-Topsoe, Consolider Ingenio 2010-Multicat, and UPV through PAID-06-11 (n.1952). MM acknowledges "Subprograma Ramon y Cajal'' for the contract RYC-2011-08972.Moliner Marin, M.; Franch MartĂ, C.; Palomares Gimeno, AE.; Grill, M.; Corma CanĂłs, A. (2012). Cu-SSZ-39, an active and hydrothermally stable catalyst for the selective catalytic reduction of NOx. Chemical Communications. 48:8264-8266. https://doi.org/10.1039/c2cc33992gS826482664
THE ACS survey of globular clusters. Xiii. Photometric calibration in comparison with stetson standards
In this study we compare the photometric data of 34 Milky Way globular clusters, observed within the Advanced Camera for Surveys (ACS) Treasury Program (PI: A. Sarajedini) with the corresponding ground-based data, provided by the Photometric Standard Field Catalogs of Stetson. We focus on the transformation between the Hubble Space Telescope/ACS F606W to V-band and F814W to I-band only. The goal is to assess the validity of the filter transformation equations by Sirianni et al. with respect to their dependence on metallicity, horizontal branch morphology, mass, and integrated (V-I) color of the various globular clusters. The transformation equations as recommended by Sirianni et al. are based on synthetic photometry, were mostly tested on NGC 2419, and may introduce additional uncertainties when applied to different stellar populations. Such a dependence is expected due to the fact that the transformation equations are based on the observations of only one globular cluster, i.e., NGC 2419. Surprisingly, the correlation between offset and metallicity is found to be weak, with a low level significance. The correlation between offset and horizontal branch structure, as well as total cluster mass is still weaker. Based on the available data we do not find the photometric offset to be linked to multiple stellar populations, e.g., as found in NGC 0288, NGC 1851, and NGC 5139. The results of this study show that there are small systematic offsets between the transformed ACS- and observed ground-based photometry, and that these are only weakly correlated, if at all, with various cluster parameters and their underlying stellar populations. As a result, investigators wishing to transform globular cluster photometry from the Sirianni et al. ground-based V, I system onto the Stetson system simply need to add -0.040 (±0.012) to the V magnitudes and -0.047 (±0.011) to the I magnitudes. This in turn means that the transformed ACS V-I colors match the ground-based values from Stetson to within 0.01 mag
The globular cluster relative ages and the milky way formation time scale
The ACS Survey of Galactic Globular Clusters is a Hubble Space Telescope (HST) Treasury program designed to provide a new large, deep and homogeneous photometric database. Based on observations from this program, we have measured precise relative ages for a sample of 64 Galactic globular clusters by comparing the relative position of the clusters' main sequence turn offs, using main-sequence fitting to cross-compare clusters within the sample. This method provides relative ages to a formal precision of 2-7%. We demonstrate that the calcidated relative ages are independent of the choice of theoretical model. We find that the Galactic globidar cluster sample can be divided into two groups - a popidation of old clusters with an intrinsic age dispersion of -Ì 3% and no age-metallicity relation, and a group of younger clusters with an age-metaUicity relation similar to that of the globular clusters associated with the Sagittarius dwarf galaxy. These results are consistent with the Milky Way halo having formed in two phases. The first phase would be compatible with a rapid (<0.8 Gyr) assembling process of the halo, in which the clusters in the old group were formed. The second phase lasted much longer in time and resulted in a group of globidar clusters with a clear age-metallicity relation. It is very tempting to argue that the origin of this second group of clusters is related to the accretion of Milky Way satelUte galaxies, but the origin of the age-metallicity relation remains unclear
Recommended from our members
The ACS Survey Of Galactic Globular Clusters. VIII. Effects Of Environment On Globular Cluster Global Mass Functions
We have used observations obtained as part of the Hubble Space Telescope/ACS Survey of Galactic Globular Clusters to construct global present-day mass functions for 17 globular clusters utilizing multi-mass King models to extrapolate from our observations to the global cluster behavior. The global present-day mass functions for these clusters are well matched by power laws from the turnoff, approximate to 0.8 M(circle dot), to 0.2-0.3 M(circle dot) on the lower main sequence. The slopes of those power-law fits, alpha, have been correlated with an extensive set of intrinsic and extrinsic cluster properties to investigate which parameters may influence the form of the present-day mass function. We do not confirm previous suggestions of correlations between alpha and either metallicity or Galactic location. However, we do find a strong statistical correlation with the related parameters central surface brightness, mu(V), and inferred central density, rho(0). The correlation is such that clusters with denser cores (stronger binding energy) tend to have steeper mass functions (a higher proportion of low-mass stars), suggesting that dynamical evolution due to external interactions may have played a key role in determining alpha. Thus, the present-day mass function may owe more to nurture than to nature. Detailed modeling of external dynamical effects is therefore a requisite for determining the initial mass function for Galactic globular clusters.NASA GO-10775, NAS 5-26555Space Telescope Science InstituteInstituto de Astrofisica de Canarias 310394Ministry of Education and Science of the Kingdom of Spain AYA-2008-67913Astronom