2,373 research outputs found
Chronic cough and esomeprazole: A double-blind placebo-controlled parallel study
Background and objective: Gastro-oesophageal reflux has been implicated in the pathogenesis of chronic cough. Guidelines on management suggest a therapeutic trial of anti-reflux medication. Esomeprazole is a proton pump inhibitor licensed for the long-term treatment of acid reflux in adults and we compared the effects of esomeprazole and placebo on patients with chronic cough. Methods: This was a prospective, single-centre, randomized, double-blind, placebo-controlled, parallel group study conducted over 8 weeks. Fifty adult non-smokers with chronic cough and normal spirometry were randomized. Patients completed cough-related quality-of-life and symptom questionnaires and subjective scores of cough frequency and severity at the beginning and end of the study. They also kept a daily diary of symptom scores. Citric acid cough challenge and laryngoscopic examination were performed at baseline and the end of the study. The primary outcome was improvement in cough score. Results: There were no differences in cough scores in the placebo and treatment arms of the study although some significant improvements were noted when compared to baseline. In the cough diary scores there was a trend towards greater improvement in the treatment arm in patients with dyspepsia. Conclusions: Esomeprazole did not have a clinically important effect greater than placebo in patients with cough. It suggests a marked placebo effect in the treatment of cough. There is paucity of evidence on which to base the treatment of reflux-associated cough. We demonstrate that acid suppressive therapy does not lead to a significant clinical effect in these patients. There may be some improvement in those with coexisting dyspeptic symptoms and therapy should be restricted to this group. © 2011 Asian Pacific Society of Respirology
High-resolution Spectroscopy of Extremely Metal-poor Stars in the Least Evolved Galaxies: Leo IV
We present high-resolution Magellan/MIKE spectroscopy of the brightest star in the ultra-faint dwarf galaxy Leo IV. We measure an iron abundance of [Fe/H] = –3.2, adding to the rapidly growing sample of extremely metal-poor (EMP) stars being identified in Milky Way satellite galaxies. The star is enhanced in the α elements Mg, Ca, and Ti by ~0.3 dex, very similar to the typical Milky Way halo abundance pattern. All of the light and iron-peak elements follow the trends established by EMP halo stars, but the neutron-capture elements Ba and Sr are significantly underabundant. These results are quite similar to those found for stars in the ultra-faint dwarfs Ursa Major II, Coma Berenices, Boötes I, and Hercules, suggesting that the chemical evolution of the lowest-luminosity galaxies may be universal. The abundance pattern we observe is consistent with predictions for nucleosynthesis from a Population III supernova explosion. The extremely low metallicity of this star also supports the idea that a significant fraction (≳10%) of the stars in the faintest dwarfs have metallicities below [Fe/H] = –3.0
A Search for Stars of Very Low Metal Abundance. VI. Detailed Abundances of 313 Metal-Poor Stars
We present radial velocities, equivalent widths, model atmosphere parameters,
and abundances or upper limits for 53 species of 48 elements derived from high
resolution optical spectroscopy of 313 metal-poor stars. A majority of these
stars were selected from the metal-poor candidates of the HK Survey of Beers,
Preston, and Shectman. We derive detailed abundances for 61% of these stars for
the first time. Spectra were obtained during a 10-year observing campaign using
the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Telescopes at
Las Campanas Observatory, the Robert G. Tull Coude Spectrograph on the Harlan
J. Smith Telescope at McDonald Observatory, and the High Resolution
Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory. We perform
a standard LTE abundance analysis using MARCS model atmospheres, and we apply
line-by-line statistical corrections to minimize systematic abundance
differences arising when different sets of lines are available for analysis. We
identify several abundance correlations with effective temperature. A
comparison with previous abundance analyses reveals significant differences in
stellar parameters, which we investigate in detail. Our metallicities are, on
average, lower by approx. 0.25 dex for red giants and approx. 0.04 dex for
subgiants. Our sample contains 19 stars with [Fe/H] < -3.5, 84 stars with
[Fe/H] < -3.0, and 210 stars with [Fe/H] < -2.5. Detailed abundances are
presented here or elsewhere for 91% of the 209 stars with [Fe/H] < -2.5 as
estimated from medium resolution spectroscopy by Beers, Preston, and Shectman.
We will discuss the interpretation of these abundances in subsequent papers.Comment: Accepted for publication in the Astronomical Journal. 60 pages, 59
figures, 18 tables. Machine-readable versions of the long tables can be found
in the ancillary data file
The Morphologies of the Small Magellanic Cloud
We compare the distribution of stars of different spectral types, and hence
mean age, within the central SMC and find that the asymmetric structures are
almost exclusively composed of young main sequence stars. Because of the
relative lack of older stars in these features, and the extremely regular
distribution of red giant and clump stars in the SMC central body, we conclude
that tides alone are not responsible for the irregular appearance of the
central SMC. The dominant physical mechanism in determining the current-day
appearance of the SMC must be star formation triggered by a hydrodynamic
interaction between gaseous components. These results extend the results of
population studies (cf. Gardiner and Hatzidimitriou) inward in radius and also
confirm the suggestion of the spheroidal nature of the central SMC based on
kinematic arguments (Dopita et al; Hardy, Suntzeff & Azzopardi). Finally, we
find no evidence in the underlying older stellar population for a ``bar'' or
``outer arm'', again supporting our classification of the central SMC as a
spheroidal body with highly irregular recent star formation.Comment: 8 pages, accepted for publication in ApJ Letters (higher quality
figures available at http://ngala.as.arizona.edu/dennis/mcsurvey.html
CTQ 839: Candidate for the Smallest Projected Separation Binary Quasar
We report the discovery of the new double quasar CTQ 839. This B = 18.3,
radio quiet quasar pair is separated by 2.1" in BRIH filters with magnitude
differences of delta m_B = 2.5, delta m_R = delta m_I = 1.9, and delta m_H =
2.3. Spectral observations reveal both components to be z = 2.24 quasars, with
relative redshifts that agree at the 100 km/s level, but exhibit pronounced
differences in the equivalent widths of related emission features, as well as
an enhancement of blue continuum flux in the brighter component longward of the
Ly alpha emission feature. In general, similar redshift double quasars can be
the result of a physical binary pair, or a single quasar multiply imaged by
gravitational lensing. Empirical PSF subtraction of R and H band images of CTQ
839 reveal no indication of a lensing galaxy, and place a detection limit of R
= 22.5 and H = 17.4 for a third component in the system. For an Einstein-de
Sitter cosmology and SIS model, the R band detection limit constrains the
characteristics of any lensing galaxy to z_lens >= 1 with a corresponding
luminosity of L >~ 5 L_*, while an analysis based on the redshift probability
distribution for the lensing galaxy argues against the existence of a z_lens >~
1 lens at the 2 sigma level. A similar analysis for a Lambda dominated
cosmology, however, does not significantly constrain the existence of any
lensing galaxy. The broadband flux differences, spectral dissimilarities, and
failure to detect a lensing galaxy make the lensing hypothesis for CTQ 839
unlikely. The similar redshifts of the two components would then argue for a
physical quasar binary. At a projected separation of 8.3/h kpc (Omega_matter =
1), CTQ 839 would be the smallest projected separation binary quasar currently
known.Comment: Latex, 23 pages including 5 ps figures; accepted for publication in
A
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No Evidence of Short-Term Exchange of Meat for Sex among Chimpanzees
The meat-for-sex hypothesis posits that male chimpanzees (Pan troglodytes) trade meat with estrous females in exchange for short-term mating access. This notion is widely cited in the anthropological literature and has been used to construct scenarios about human evolution. Here we review the theoretical and empirical basis for the meat-for-sex hypothesis. We argue that chimpanzee behavioral ecology does not favor the evolution of such exchanges because 1) female chimpanzees show low mate selectivity and require little or no material incentive to mate, violating existing models of meat-for-sex exchange; and 2) meat-for-sex exchanges are unlikely to provide reproductive benefits to either partner. We also present new analyses of 28 years of data from two East African chimpanzee study sites (Gombe National Park, Tanzania; Kanyawara, Kibale National Park, Uganda) and discuss the results of previously published studies. In at least three chimpanzee communities, 1) the presence of sexually receptive females did not increase hunting probability; 2) males did not share preferentially with sexually receptive females and 3) sharing with females did not increase a male’s short-term mating success. We acknowledge that systematic meat-sharing by male chimpanzees in expectation of or as reward for immediate copulations might be discovered in future studies of chimpanzees. However current data indicate that such exchanges are so rare in studied populations, and are so different in nature from exchanges among humans, that with respect to chimpanzees, sexual bartering in humans should be regarded as a derived trait with no known antecedents in the behavior of wild chimpanzees.Human Evolutionary Biolog
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