Gemini/GMOS search of massive binaries in the ionizing cluster of 30 Dor

If binaries are common among massive stars, it will have important consequences for the derivation of fundamental properties like the cluster age, IMF and dynamical mass. Making use of the multiplexing facilities of Gemini Multi Object Spectrograph (GMOS) we were able to investigate the presence of binary stars within the ionising cluster of 30 Doradus. From a seven epochs observing campaign at Gemini South we detect a binary candidate rate of about 50%, which is consistent with an intrinsic 100% binary rate among massive stars. We find that single epoch determinations of the velocity dispersion give values around 30 km/s . After correcting the global velocity dispersion for the binary orbital motions, the true cluster velocity dispersion is 8.3 km/s. This value implies a virial mass of about 4.5E5 Msun or 8 percent of the mass calculated using the single epoch value. The binary corrected virial mass estimate is consistent with photometric mass determinations thus suggesting that NGC 2070 is a firm candidate for a future globular cluster.Comment: 9 pages, accepted at Astronomical Journa

Spectroscopic study of the N159/N160 complex in the Large Magellanic Cloud

We present a spectroscopic study of the N159/N160 massive-star forming region south of 30 Doradus in the Large Magellanic Cloud, classifying a total of 189 stars in the field of the complex. Most of them belong to O and early B spectral classes; we have also found some uncommon and very interesting spectra, including members of the Onfp class, a Be P Cygni star, and some possible multiple systems. Using spectral types as broad indicators of evolutionary stages, we considered the evolutionary status of the region as a whole. We infer that massive stars at different evolutionary stages are present throughout the region, favoring the idea of a common time for the origin of recent star formation in the N159/N160 complex as a whole, while sequential star formation at different rates is probably present in several subregions.Comment: 36 pages, 24 figures (127 spectra mostly OB stars, 4 field images). Published in The Astronomical Journa

Accelerated Variant of Idiopathic Pulmonary Fibrosis: Clinical Behavior and Gene Expression Pattern

Idiopathic pulmonary fibrosis (IPF) is characterized by the insidious onset of dyspnea or cough. However, a subset of patients has a short duration of symptoms with rapid progression to end-stage disease. In this study, we evaluated clinical and molecular features of "rapid" and "slow" progressors with IPF

Narrowband CCD Photometry of Giant HII Regions

We have obtained accurate CCD narrow band H_beta and H_alpha photometry of Giant HII Regions in M 33, NGC 6822 and M 101. Comparison with previous determinations of emission line fluxes show large discrepancies; their probable origins are discussed. Combining our new photometric data with global velocity dispersion (sigma) derived from emission line widths we have reviewed the L(H_beta)-sigma relation. A reanalysis of the properties of the GEHRs included in our sample shows that age spread and the superposition of components in multiple regions introduce a considerable spread in the regression. Combining the information available in the literature regarding ages of the associated clusters, evolutionary footprints on the interstellar medium, and kinematical properties of the knots that build up the multiple GEHRs, we have found that a subsample - which we refer to as young and single GEHRs - do follow a tight relation in the L-sigma plane.Comment: Accepted for publication in MNRAS, large figures available on a separate tarfil

A Genetic Screen for Dihydropyridine (DHP)-Resistant Worms Reveals New Residues Required for DHP-Blockage of Mammalian Calcium Channels

Dihydropyridines (DHPs) are L-type calcium channel (Cav1) blockers prescribed to treat several diseases including hypertension. Cav1 channels normally exist in three states: a resting closed state, an open state that is triggered by membrane depolarization, followed by a non-conducting inactivated state that is triggered by the influx of calcium ions, and a rapid change in voltage. DHP binding is thought to alter the conformation of the channel, possibly by engaging a mechanism similar to voltage dependent inactivation, and locking a calcium ion in the pore, thereby blocking channel conductance. As a Cav1 channel crystal structure is lacking, the current model of DHP action has largely been achieved by investigating the role of candidate Cav1 residues in mediating DHP-sensitivity. To better understand DHP-block and identify additional Cav1 residues important for DHP-sensitivity, we screened 440,000 randomly mutated Caenorhabditis elegans genomes for worms resistant to DHP-induced growth defects. We identified 30 missense mutations in the worm Cav1 pore-forming (α1) subunit, including eleven in conserved residues known to be necessary for DHP-binding. The remaining polymorphisms are in eight conserved residues not previously associated with DHP-sensitivity. Intriguingly, all of the worm mutants that we analyzed phenotypically exhibited increased channel activity. We also created orthologous mutations in the rat α1C subunit and examined the DHP-block of current through the mutant channels in culture. Six of the seven mutant channels examined either decreased the DHP-sensitivity of the channel and/or exhibited significant residual current at DHP concentrations sufficient to block wild-type channels. Our results further support the idea that DHP-block is intimately associated with voltage dependent inactivation and underscores the utility of C. elegans as a screening tool to identify residues important for DHP interaction with mammalian Cav1 channels

Stellar kinematics in 30 Doradus

Con espectroscopía multiranura de 180 estrellas en el cumulo ionizante de 30 Doradus, hemos obtenido velocidades radiales confiables para 58 estrellas. Con ellas, calculamos la dispersión de velocidades, la cual es de 35 km s-1. Si el cúmulo está relajado dinámicamente, la masa virial estimada es de ~ 1 x 107 M.From multislit spectroscopy of 180 stars in the ionising cluster of 30 Doradus, we have obtained reliable stellar radial velocities for 58 stars. With these we calculated the stellar radial velocity dispersion and found it to be 35 km s-1 . If the cluster is dinamically relaxed the virial mass is ~ 1 x 107 M.Facultad de Ciencias Astronómicas y Geofísica

Stellar kinematics in 30 Doradus

Con espectroscopía multiranura de 180 estrellas en el cumulo ionizante de 30 Doradus, hemos obtenido velocidades radiales confiables para 58 estrellas. Con ellas, calculamos la dispersión de velocidades, la cual es de 35 km s-1. Si el cúmulo está relajado dinámicamente, la masa virial estimada es de ~ 1 x 107 M.From multislit spectroscopy of 180 stars in the ionising cluster of 30 Doradus, we have obtained reliable stellar radial velocities for 58 stars. With these we calculated the stellar radial velocity dispersion and found it to be 35 km s-1 . If the cluster is dinamically relaxed the virial mass is ~ 1 x 107 M.Facultad de Ciencias Astronómicas y Geofísica

Stochastic prediction of drought class transitions

This paper aims at the stochastic characterization of droughts applying Markov chains modeling to drought class transitions derived from SPI time series. Several sites in Southern Portugal having updated data on precipitation available were considered. The drought class probabilities, the expected residence time in each class of severity, the expected time for the transition between drought classes and the drought severity class predictions 1, 2, or 3 months ahead have been obtained. Those predictions are then compared with observed drought classes for the recent drought periods of 2003–2006. In addition, the estimation of the cumulated precipitation deficits, amount of monthly precipitation needed to decrease drought severity, and foreseen SPI values depending on different precipitation scenarios are also presented as complementing the prediction of drought class transitions

Development of an immunoradiometric assay for quantitative determination of CrylA(b) protein in transgenic sugarcane plants

An immunoradiometric assay (IRMA) system was performed to quantify the recombinant CrylA(b) protein produced by transgenic sugarcane lines. The method allowed detection of 0.1–1 ng CrylA(b) per 25 μg of soluble protein in leaf extracts from plants transformed with an expression vector containing a truncated version of the crylA(b) gene from Bacillus thuringiensis. The technique was based upon the use of radioiodinated immunopurified antibodies specific to natural CrylA proteins in a one-step sandwich procedure by direct simultaneous incubation of the leaf extracts with the detecting antibody solution. This IRMA system provides a simple routine method to quantify the CrylA proteins in transgenic plants with different expression levels. We suggest that the methodology presented herein may become an efficient tool to quanify heterologous or native plant proteins, present at low levels in tissue extracts