60 research outputs found
Hereditary angioedema: quality of life in Brazilian patients
OBJECTIVE: Hereditary angioedema is a serious medical condition caused by a rare autosomal dominant genetic disorder and it is associated with deficient production or dysfunction of the C1 esterase inhibitor. In most cases, affected patients experience unexpected and recurrent crises of subcutaneous, gastrointestinal and laryngeal edema. The unpredictability, intensity and other factors associated with the disease impact the quality of life of hereditary angioedema patients. We evaluated the quality of life in Brazilian hereditary angioedema patients. METHODS: Patients older than 15 years with any severity of hereditary angioedema and laboratory confirmation of C1 inhibitor deficiency were included. Two questionnaires were used: a clinical questionnaire and the SF-36 (a generic questionnaire). This protocol was approved by the Ethics Committee of Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. RESULTS: The SF-36 showed that 90.4% (mean) of all the patients had a score below 70 and 9.6% had scores equal to or higher than 70. The scores of the eight dimensions ranged from 51.03 to 75.95; vitality and social aspects were more affected than other arenas. The internal consistency of the evaluation was demonstrated by a Cronbach's alpha value above 0.7 in seven of the eight domains. CONCLUSIONS: In this study, Brazilian patients demonstrated an impaired quality of life, as measured by the SF-36. The most affected domains were those related to vitality and social characteristics. The generic SF-36 questionnaire was relevant to the evaluation of quality of life; however, there is a need for more specific instruments for better evaluation
The Ultraviolet Spectrum and Physical Properties of the Mass Donor Star in HD 226868 = Cygnus X-1
We present an examination of high resolution, ultraviolet spectroscopy from
Hubble Space Telescope of the photospheric spectrum of the O-supergiant in the
massive X-ray binary HD 226868 = Cyg X-1. We analyzed this and ground-based
optical spectra to determine the effective temperature and gravity of the O9.7
Iab supergiant. Using non-local thermodynamic equilibrium (non-LTE), line
blanketed, plane parallel models from the TLUSTY grid, we obtain T_eff = 28.0
+/- 2.5kK and log g > 3.00 +/- 0.25, both lower than in previous studies. The
optical spectrum is best fit with models that have enriched He and N
abundances. We fit the model spectral energy distribution for this temperature
and gravity to the UV, optical, and IR fluxes to determine the angular size of
and extinction towards the binary. The angular size then yields relations for
the stellar radius and luminosity as a function of distance. By assuming that
the supergiant rotates synchronously with the orbit, we can use the radius -
distance relation to find mass estimates for both the supergiant and black hole
as a function of the distance and the ratio of stellar to Roche radius. Fits of
the orbital light curve yield an additional constraint that limits the
solutions in the mass plane. Our results indicate masses of 23^{+8}_{-6} M_sun
for the supergiant and 11^{+5}_{-3} M_sun for the black hole.Comment: ApJ in pres
The R136 star cluster dissected with Hubble Space Telescope/STIS. I. Far-ultraviolet spectroscopic census and the origin of HeII 1640 in young star clusters
We introduce a HST/STIS stellar census of R136a, the central ionizing star
cluster of 30 Doradus. We present low resolution far-ultraviolet STIS/MAMA
spectroscopy of R136 using 17 contiguous 52x0.2 arcsec slits which together
provide complete coverage of the central 0.85 parsec (3.4 arcsec). We provide
spectral types of 90% of the 57 sources brighter than m_F555W = 16.0 mag within
a radius of 0.5 parsec of R136a1, plus 8 additional nearby sources including
R136b (O4\,If/WN8). We measure wind velocities for 52 early-type stars from CIV
1548-51, including 16 O2-3 stars. For the first time we spectroscopically
classify all Weigelt & Baier members of R136a, which comprise three WN5 stars
(a1-a3), two O supergiants (a5-a6) and three early O dwarfs (a4, a7, a8). A
complete Hertzsprung-Russell diagram for the most massive O stars in R136 is
provided, from which we obtain a cluster age of 1.5+0.3_-0.7 Myr. In addition,
we discuss the integrated ultraviolet spectrum of R136, and highlight the
central role played by the most luminous stars in producing the prominent HeII
1640 emission line. This emission is totally dominated by very massive stars
with initial masses above ~100 Msun. The presence of strong HeII 1640 emission
in the integrated light of very young star clusters (e.g A1 in NGC 3125)
favours an initial mass function extending well beyond a conventional upper
limit of 100 Msun. We include montages of ultraviolet spectroscopy for LMC O
stars in the Appendix. Future studies in this series will focus on optical
STIS/CCD medium resolution observations.Comment: 20 pages plus four Appendices providing LMC UV O spectral templates,
UV spectral atlas in R136, wind velocities of LMC O stars and photometry of
additional R136 source
Stellar Wind Variations During the X-ray High and Low States of Cygnus X-1
We present results from Hubble Space Telescope UV spectroscopy of the massive
X-ray binary system, HD226868 = Cyg X-1. The spectra were obtained at both
orbital conjunction phases in two separate runs in 2002 and 2003 when the
system was in the X-ray high/soft state. The stellar wind lines suffer large
reductions in strength when the black hole is in the foreground due to the
X-ray ionization of the wind ions. A comparison of HST and archival IUE spectra
shows that similar photoionization effects occur in both the X-ray states. We
constructed model UV wind line profiles assuming that X-ray ionization occurs
everywhere in the wind except the zone where the supergiant blocks the X-ray
flux. The good match between the observed and model profiles indicates that the
wind ionization extends to near to the hemisphere of the supergiant facing the
X-ray source. The H-alpha emission strength is generally lower in the high/soft
state compared to the low/hard state, but the He II 4686 emission is relatively
constant between states. The results suggest that mass transfer in Cyg X-1 is
dominated by a focused wind flow that peaks along the axis joining the stars
and that the stellar wind contribution is shut down by X-ray photoionization
effects. The strong stellar wind from the shadowed side of the supergiant will
stall when Coriolis deflection brings the gas into the region of X-ray
illumination. This stalled gas component may be overtaken by the orbital motion
of the black hole and act to inhibit accretion from the focused wind. The
variations in the strength of the shadow wind component may then lead to
accretion rate changes that ultimately determine the X-ray state.Comment: ApJ, in press, 41 pages, 15 figure
Joint H-alpha and X-Ray Observations of Massive X-Ray Binaries. II. The Be X-ray Binary and Microquasar LS I +61 303
We present the results of an H-alpha monitoring campaign on the BeXRB and
microquasar system LS I +61 303. We use radial velocity measurements of HeI
lines in our spectra to re-evaluate the orbital elements and to better
establish the time of periastron. We list equivalent widths and other
parameters for the H-alpha emission line and discuss the orbital phase related
variations observed. We call attention to a dramatic episode of emission
weakening that occurred in less than a day that probably resulted from exposure
to a transient source of ionizing radiation. We argue that the increase in
H-alpha and X-ray emission following periastron probably results from the
creation of an extended density wave in the disk created by tidal forces. We
also discuss estimates of the size of the disk from the H-alpha equivalent
width measurements, and we suggest that the disk radius from the average
equivalent width corresponds to a resonant truncation radius of the disk while
the maximum equivalent width corresponds to a radius limited by the separation
of the stars at periastron. We note that a nearby faint companion is probably
an unrelated foreground object.Comment: 18 pages including 7 figures and 2 tables, accepted to Ap
The Multiplicity of Massive Stars: A High Angular Resolution Survey with the HST Fine Guidance Sensor
We present the results of an all-sky survey made with the Fine Guidance
Sensor on Hubble Space Telescope to search for angularly resolved binary
systems among the massive stars. The sample of 224 stars is comprised mainly of
Galactic O- and B-type stars and Luminous Blue Variables, plus a few luminous
stars in the Large Magellanic Cloud. The FGS TRANS mode observations are
sensitive to detection of companions with an angular separation between 0."01
and 1."0 and brighter than . The FGS observations resolved 52
binary and 6 triple star systems and detected partially resolved binaries in 7
additional targets (43 of these are new detections). These numbers yield a
companion detection frequency of 29% for the FGS survey. We also gathered
literature results on the numbers of close spectroscopic binaries and wider
astrometric binaries among the sample, and we present estimates of the
frequency of multiple systems and the companion frequency for subsets of stars
residing in clusters and associations, field stars, and runaway stars. These
results confirm the high multiplicity fraction, especially among massive stars
in clusters and associations. We show that the period distribution is
approximately flat in increments of log P. We identify a number of systems of
potential interest for long term orbital determinations, and we note the
importance of some of these companions for the interpretation of the radial
velocities and light curves of close binaries that have third companions.Comment: 37 pages, 4 figures, 5 tables; AJ, in press; Full version with
extended tables and large figure set can be found:
http://www.astro.umontreal.ca/~emily/fgs.pd
The Survey for Ionization in Neutral-Gas Galaxies: III. Diffuse, Warm Ionized Medium and Escape of Ionizing Radiation
We use the first data release from the SINGG H-alpha survey of HI-selected
galaxies to study the quantitative behavior of the diffuse, warm ionized medium
(WIM) across the range of properties represented by these 109 galaxies. The
mean fraction f_WIM of diffuse ionized gas in this sample is 0.59+/- 0.19,
slightly higher than found in previous samples. Since lower surface-brightness
galaxies tend to have higher f_WIM, we believe that most of this difference is
due to selection effects favoring large, optically-bright, nearby galaxies with
high star-formation rates. As found in previous studies, there is no
appreciable correlation with Hubble type or total star-formation rate. However,
we find that starburst galaxies, defined here by an H-alpha surface brightness
> 2.5x 10^39 erg s^-1 kpc^-2 within the H-alpha half-light radius, do show much
lower fractions of diffuse H-alpha emission. The cause apparently is not
dominated by a lower fraction of field OB stars. However, it is qualitatively
consistent with an expected escape of ionizing radiation above a threshold
star-formation rate, predicted from our model in which the ISM is shredded by
pressure-driven supernova feedback. The HI gas fractions in the starburst
galaxies are also lower, suggesting that the starbursts are consuming and
ionizing all the gas, and thus promoting regions of density-bounded ionization.
If true, these effects imply that some amount of Lyman continuum radiation is
escaping from most starburst galaxies, and that WIM properties and outflows
from mechanical feedback are likely to be pressure-driven. However, in view of
previous studies showing that the escape fraction of ionizing radiation is
generally low, it is likely that other factors also drive the low fractions of
diffuse ionized gas in starbursts.Comment: 16 pages plus separate 2-page PostScript table. Accepted to the
Astrophysical Journa
A high angular resolution survey of massive stars in Cygnus OB2 : JHK adaptive optics results from the Gemini Near-Infrared Imager
We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the NIRI camera and ALTAIR adaptive optics system of the Gemini North telescope. We observed 74 O- and early B-type stars in Cyg OB2 in the JHK infrared bands in order to detect binary and multiple companions. The observations are sensitive to equal-brightness pairs at separations as small as 0.08 \arcsec, and progressively fainter companions are detectable out to Δ K = 9 mag at a separation of 2 arcsec. This faint contrast limit due to readnoise continues out to 10 arcsec near the edge of the detector. We assigned a simple probability of chance alignment to each companion based upon its separation and magnitude difference from the central target star and upon areal star counts for the general star field of Cyg OB2. Companion stars with a field membership probability of less than 1% are assumed to be physical companions. This assessment indicates that 47% of the targets have at least one resolved companion that is probably gravitationally bound. Including known spectroscopic binaries, our sample includes 27 binary, 12 triple, and 9 systems with four or more components. These results confirm studies of high mass stars in other environments that find that massive stars are born with a high multiplicity fraction. The results are important for the placement of the stars in the H-R diagram, the interpretation of their spectroscopic analyses, and for future mass determinations through measurement of orbital motion
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