Bruno Dias

Cardiopulmonary Manifestations of Hepatosplenic Schistosomiasis

Background— Schistosomiasis is a highly prevalent disease with >200 million infected people. Pulmonary hypertension is one of the pulmonary manifestations in this disease, particularly in its hepatosplenic presentation. The aim of this study was to determine the prevalence of pulmonary hypertension in schistosomiasis patients with the hepatosplenic form of the disease. Methods and Results— All patients with hepatosplenic schistosomiasis followed up at the gastroenterology department of our university hospital underwent echocardiographic evaluation to search for pulmonary hypertension. Patients presenting with systolic pulmonary artery pressure >40 mm Hg were further evaluated through right heart catheterization. Our study showed an 18.5% prevalence of patients with elevated systolic pulmonary artery pressure at echocardiography. Invasive hemodynamics confirmed the presence of pulmonary hypertension in 7.7% (95% confidence interval, 3.3 to 16.7) of patients, with a prevalence of precapillary (arterial) pulmonary hypertension of 4.6% (95% confidence interval, 1.5 to 12.7). Conclusions— Our study reinforces the role of echocardiography as a screening tool in the investigation of pulmonary hypertension, together with the need for invasive monitoring for a proper diagnosis. We conclude that hepatosplenic schistosomiasis may account for one of the most prevalent forms of pulmonary hypertension worldwide, justifying the development of further studies to evaluate the effect of specific pulmonary hypertension treatment in this particular form of the disease.

New Galactic star clusters discovered in the VVV survey

Context. VISTA Variables in the V´oa Lactea (VVV) is one of the six ESO Public Surveys operating on the new 4-meter Visible and Infrared Survey Telescope for Astronomy (VISTA). VVV is scanning the Milky Way bulge and an adjacent section of the disk, where star formation activity is high. One of the principal goals of the VVV Survey is to find new star clusters of different ages. Aims. In order to trace the early epochs of star cluster formation we concentrated our search in the directions to those of known star formation regions, masers, radio, and infrared sources. Methods. The disk area covered by VVV was visually inspected using the pipeline processed and calibrated KS-band tile images for stellar overdensities. Subsequently, we examined the composite JHKS and ZJKS color images of each candidate. PSF photometry of 15 × 15 arcmin fields centered on the candidates was then performed on the Cambridge Astronomy Survey Unit reduced images. After statistical field-star decontamination, color-magnitude and color-color diagrams were constructed and analyzed. Results. We report the discovery of 96 new infrared open clusters and stellar groups. Most of the new cluster candidates are faint and compact (with small angular sizes), highly reddened, and younger than 5Myr. For relatively well populated cluster candidates we derived their fundamental parameters such as reddening, distance, and age by fitting the solar- metallicity Padova isochrones to the color-magnitude diagrams.

Milky Way demographics with the VVV survey - I. The 84-million star colour–magnitude diagram of the Galactic bulge

Context. The Milky Way (MW) bulge is a fundamental Galactic componentfor understanding the formation and evolution of galaxies, in particular our own. The ESO Public Survey VISTA Variables in the V´ ia Lactea is a deep near-IR survey mapping the Galactic bulge and southern plane. Particularly for the bulge area, VVV is c overing∼ 315 deg 2 . Data taken during 2010 and 2011 covered the entire bulge area in the JHKs bands. Aims. We used VVV data for the whole bulge area as a single and homogeneous data set to build for the first time a single colour- magnitude diagram (CMD) for the entire Galactic bulge. Methods. Photometric data in the JHKs bands were combined to produce a single and huge data set containing 173, 150, 467 sources in the three bands, for the∼ 315 deg 2 covered by VVV in the bulge. Selecting only the data points fla gged as stellar, the total number of sources is 84, 095, 284. Results. We built the largest colour-magnitude diagrams published up to date, containing 173.1+ million sources for all data points, and more than 84.0 million sources accounting for the stellar sources only. The CMD has a complex shape, mostly owing to the complexity of the stellar population and the effects of extinction and reddening towards the Galactic centr e. The red clump (RC) giants are seen double in magnitude at b∼−8 ◦ − 10 ◦ , while in the inner part (b∼−3 ◦ ) they appear to be spreading in colour, or even splitting into a secondary peak. Stellar population models show the predominance of main-sequence and giant stars. The analysis of the outermost bulge area reveals a well-defined sequence of l ate K and M dwarfs, seen at (J− Ks)∼ 0.7− 0.9 mag and Ks& 14 mag. Conclusions. The interpretation of the CMD yields important information about the MW bulge, showing the fingerprint of its structure and content. We report a well-defined red dwarf sequence in th e outermost bulge, which is important for the planetary tran sit searches of VVV. The double RC in magnitude seen in the outer bulge is the signature of the X-shaped MW bulge, while the spreading of the RC in colour, and even its splitting into a secondary peak, ar e caused by reddening effects. The region around the Galactic centre is harder to interpret because it is strongly affected by reddening and extinction.

Pulmonary Arterial Hypertension in the Southern Hemisphere

BACKGROUND Pulmonary arterial hypertension (PAH) is a rare and ultimately fatal disorder of the pulmonary vasculature. There is increasing interest in the worldwide characteristics of patients with PAH, although data coming from the Southern Hemisphere remain scarce. The objective of this study was to describe a cohort of incident patients with PAH from a large reference center in Brazil. METHODS All consecutive patients who received a diagnosis of PAH by right-sided heart catheterization between 2008 and 2013 were included in the study. RESULTS A total of 178 patients with newly diagnosed PAH were enrolled in the study (mean age, 46 years; female/male ratio, 3.3:1; 45.5% in New York Heart Association functional class III or IV). Idiopathic PAH (IPAH), connective tissue disease (CTD), and schistosomiasis-associated PAH (Sch-PAH) accounted for 28.7%, 25.8%, and 19.7% of all cases, respectively. The patients were treated with phosphodiesterase type 5 inhibitors (66%), endothelin receptor antagonists (27%), or a combination of both (5%). For the PAH group as a whole, the estimated survival rate 3 years after diagnosis was 73.9%. The prognosis for the patients with CTD was worse than that for the patients with IPAH and Sch-PAH (P = .03). CONCLUSIONS The distribution of PAH causes and the baseline characteristics in our registry clearly differ from the previously published European and US-based registries. These differences highlight the importance of regional registries and also raise questions regarding the need to better account for such differences in future clinical trials.

Skeletal muscle abnormalities in pulmonary arterial hypertension.

Background Pulmonary arterial hypertension is a progressive disease that is characterized by dyspnea and exercise intolerance. Impairment in skeletal muscle has recently been described in PAH, although the degree to which this impairment is solely determined by the hemodynamic profile remains uncertain. The aim of this study was to verify the association of structural and functional skeletal muscle characteristics with maximum exercise in PAH. Methods The exercise capacity, body composition, CT area of limb muscle, quality of life, quadriceps biopsy and hemodynamics of 16 PAH patients were compared with those of 10 controls. Results PAH patients had a significantly poorer quality of life, reduced percentage of lean body mass, reduced respiratory muscle strength, reduced resistance and strength of quadriceps and increased functional limitation at 6MWT and CPET. VO2 max was correlated with muscular variables and cardiac output. Bivariate linear regression models showed that the association between muscular structural and functional variables remained significant even after correcting for cardiac output. Conclusion Our study showed the coexistence of ventilatory and quadriceps weakness in face of exercise intolerance in the same group of PAH patients. More interestingly, it is the first time that the independent association between muscular pattern and maximum exercise capacity is evidenced in PAH, independently of cardiac index highlighting the importance of considering rehabilitation in the treatment strategy for PAH.

FORS2/VLT survey of Milky Way globular clusters - I. Description of the method for derivation of metal abundances in the optical and application to NGC 6528, NGC 6553, M 71, NGC 6558, NGC 6426, and Terzan 8

We are grateful to Paula Coelho for useful discussions. B.D. acknowledges financial support from CNPq and ESO. B.B. acknowledges partial financial support from CNPq and Fapesp.

Deriving metallicities from calcium triplet spectroscopy in combination with near-infrared photometry

Context. When established with sufficient precision the ages, metallicities and kinematics of the Galactic globular clusters (GGCs) can shed much light on the dynamical and chemical evolution of the Galactic halo and bulge. While the most fundamental way to determine GC abundances is via high resolution spectroscopy, in practice this method is limited to only the brighter stars in the nearest and less reddened objects. This restriction has, over the years, led to the development of a large number of techniques that measure the overall abundance indirectly, from parameters that correlate with overall metallicity. One of the most efficient methods is the measurement of the equivalent width (EW) of the Calcium II Triplet (CaT) at λ ≈ 8500A in red giants, corrected for the luminosity and temperature effects via V magnitude differences from the horizontal branch (HB). Aims. We establish a similar method in the NIR, combining the power of the differential magnitudes technique with the advantages of NIR photometry in minimizing differential reddening effects Methods. We use the Ks magnitude difference between the star and the reddest part of the HB (RHB) or of the Red Clump (RC) to generate reduced equivalent widths (rEW) from the datasets presented in Saviane et al. (2012) and Rutledge et al. (1997) Subsequently we calibrated these rEW against three different metallicity scales: the one presented in Carretta et al. (2009), the metallicity values given in Harris (2010) and a version of the former corrected via high-resolution spectroscopic metallicities. Results. We calculated the calibration relations for the two datasets and the three metallicity scales and found that they are approximately equivalent, with differences almost negligible. We compared our nIR calibrations with the corresponding optical ones, and found them to be equivalent, establishing that the luminosity-corrected rEW using the Ks magnitude is compatible with the one obtained from the V magnitude. We then used the metallicities obtained from the calibration to investigate the internal metallicity distributions of the GCs. Conclusions. We have established that the ([Fe/H]:rEW) relation is independent from the magnitude used for the luminosity correction and find that the calibration relations only change slightly for different metallicity scales. The CaT technique using NIR photometry is thus a powerful tool to derive metallicities. In particular, it can be used to study the internal metallicity spread of a GC. We confirm the presence of at least two metallicity populations in NGC 6656 and find that several other GCs present peculiar metallicity distributions.

Probing the Large Magellanic Cloud age gap at intermediate cluster masses

The LMC has a rich star cluster system spanning a wide range of ages and masses. One striking feature of the LMC cluster system is the existence of an age gap between 3-10 Gyrs. But this feature is not as clearly seen among field stars. Three LMC fields containing relatively poor and sparse clusters whose integrated colours are consistent with those of intermediate age simple stellar populations have been imaged in BVI with the Optical Imager (SOI) at the Southern Telescope for Astrophysical Research (SOAR). A total of 6 clusters, 5 of them with estimated initial masses M < 10^4M_sun, were studied in these fields. Photometry was performed and Colour-Magnitude Diagrams (CMD) were built using standard point spread function fitting methods. The faintest stars measured reach V ~ 23. The CMD was cleaned from field contamination by making use of the three-dimensional colour and magnitude space available in order to select stars in excess relative to the field. A statistical CMD comparison method was developed for this purpose. The subtraction method has proven to be successful, yielding cleaned CMDs consistent with a simple stellar population. The intermediate age candidates were found to be the oldest in our sample, with ages between 1-2 Gyrs. The remaining clusters found in the SOAR/SOI have ages ranging from 100 to 200 Myrs. Our analysis has conclusively shown that none of the relatively low-mass clusters studied by us belongs to the LMC age-gap.

Self-consistent physical parameters for five intermediate-age SMC stellar clusters from CMD modelling

Context. Stellar clusters in the Small Magellanic Cloud (SMC) are useful probes for studying the chemical and dynamical evolution of this neighbouring dwarf galaxy, enabling inspection of a large period covering over 10 Gyr. Aims: The main goals of this work are the derivation of age, metallicity, distance modulus, reddening, core radius, and central density profiles for six sample clusters, in order to place them in the context of the Small Cloud evolution. The studied clusters are AM 3, HW 1, HW 34, HW 40, Lindsay 2, and Lindsay 3; HW 1, HW 34, and Lindsay 2 are studied for the first time. Methods: Optical colour-magnitude diagrams (V,B - V CMDs) and radial density profiles were built from images obtained with the 4.1 m Southern Astrophysical Research (SOAR) telescope, reaching V ~ 23. The determination of structural parameters were carried out by applying King profile fitting. The other parameters were derived in a self-consistent way by means of isochrone fitting, which uses likelihood statistics to identify the synthetic CMDs that best reproduce the observed ones. Membership probabilities were determined comparing the cluster and control field CMDs. Completeness and photometric uncertainties were obtained by performing artificial star tests. Results: The results confirm that these clusters (except HW 34, identified as a field fluctuation) are intermediate-age clusters, with ages between 1.2 Gyr (Lindsay 3) and ~5.0 Gyr (HW 1). In particular HW 1, Lindsay 2 and Lindsay 3 are located in a region that we called West Halo, where studies of ages and metallicity gradients are still lacking. Moreover, Lindsay 2 was identified as a moderately metal-poor cluster with [Fe/H] = -1.4 +/- 0.2 dex, lower than expected from the age-metallicity relation by Pagel & Tautvaisiene (1998). We also found distances varying from ~53 kpc to 66 kpc, compatible with the large depth of the SMC.

SMC west halo: a slice of the galaxy that is being tidally stripped? - Star clusters trace age and metallicity gradients

(ABRIDGED) The evolution and structure of the Magellanic Clouds is presently under debate. The classical scenario where both the Large and Small Magellanic Clouds (LMC, SMC) are orbiting the Milky Way has been challenged by an alternative where the LMC and SMC are in their first close passage to our Galaxy. Detailed studies of stellar populations in the galaxies should constrain the proposed scenarios. In particular, the west halo of the SMC was recently characterized with radial trends in age and metallicity which indicates tidal disruption. We increase the sample of star clusters in the west halo of the SMC with homogeneous age, metallicity, and distance derivations, to determine better age and metallicity gradients. Comparisons of observed and synthetic V,(B-V) colour-magnitude diagrams are used to derive parameters for west halo star clusters. We derived age and metallicity for the reference cluster NGC 152 compatible with literature parameters. Age and metallicity gradients are confirmed in the west halo: 2.6 +/- 0.6 Gyr/deg and -0.19 +/- 0.09 dex/deg, respectively. Age-metallicity relation for the west halo has low dispersion in metallicity and it is compatible with a burst model of chemical enrichment. All WH clusters seem to follow the same predicted stellar distribution, with exception of AM-3 that should belong to the counter-bridge. Bruck 6 is only 130 +/- 40 Myr old and it could have been formed during a recent tidal interaction of the SMC-LMC. We suggest that it is crucial to split the SMC cluster population in groups: main body, wing/bridge, counter-bridge and west halo. This is the way to analyse the complex star formation and dynamical history of our neighbour. In particular we show that west halo has clear age and metallicity gradients and age-metallicity relation, also compatible with the dynamical model of tidal influence of the LMC over the SMC.