Our FLAMES survey of Na-O anticorrelation in globular clusters (GCs) is extended to NGC 4833, a metal-poor GC with a long blue tail on the horizontal branch (HB). We present the abundance analysis ...for a large sample of 78 red giants based on UVES and GIRAFFE spectra acquired at the ESO-VLT. We derived abundances of Na, O, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Ba, La, and Nd. This is the first extensive study of this cluster from high resolution spectroscopy. On the scale of our survey, the metallicity of NGC 4833 is Fe/H = −2.015 ± 0.004 ± 0.084 dex (rms = 0.014 dex) from 12 stars observed with UVES, where the first error is from statistics and the second one refers to the systematic effects. The iron abundance in NGC 4833 is homogeneous at better than 6%. On the other hand, the light elements involved in proton-capture reactions at high temperature show the large star-to-star variations observed in almost all GCs studied so far. The Na-O anticorrelation in NGC 4833 is quite extended, as expected from the high temperatures reached by stars on the HB, and NGC 4833 contains a conspicuous fraction of stars with extreme O/Na ratios. More striking is the finding that large star-to-star variations are also seen for Mg, which spans a range of more than 0.5 dex in this GC. Depletions in Mg are correlated to the abundances of O and anti-correlated with Na, Al, and Si abundances. This pattern suggests the action of nuclear processing at unusually high temperatures, producing the extreme chemistry observed in the stellar generations of NGC 4833. These extreme changes are also seen in giants of the much more massive GCs M 54 and ω Cen, and our conclusion is that NGC 4833 has probably lost a conspicuous fraction of its original mass due to bulge shocking, as also indicated by its orbit.
Empirical abundance maps derived with the help of Zeeman Doppler mapping are found to be at variance with the predictions of numerical models of atomic diffusion in magnetic atmospheres of ApBp ...stars. Although theory has often been made responsible for this lack of agreement, direct spectral synthesis based on the published abundance maps reveals that all the chemical inhomogeneities claimed for HD 3980 are entirely spurious, and those of HD 50773 to a large extent. In the former case, this is shown to be due to the neglect of a strong magnetic field, and in the latter case, due to noisy spectra in combination with considerable rotational broadening and ensuing strong line blending. Doppler maps for other magnetic ApBp stars could be affected by similar problems. It is also pointed out that the patchy, extreme overabundances in HD 3980 cannot be reconciled with the theory of stellar atmospheres.
To determine the prevalence of and factors associated with amblyopia in a sample of Australian preschool children.
Population-based, cross-sectional study.
The Sydney Paediatric Eye Disease Study ...examined 2461 (73.8% participation) children aged between 6 and 72 months from 2007 to 2009.
Visual acuity (VA) was assessed in children aged ≥ 30 months using the Electronic Visual Acuity system, and a subset using the logarithm of the minimum angle of resolution chart. Amblyopia was categorized into unilateral and bilateral subtypes: Unilateral amblyopia was defined as a 2-line difference in reduced VA between the 2 eyes, in addition to strabismus, anisometropia, and/or visual axis obstruction; bilateral amblyopia was defined as bilateral reduced VA with either bilateral visual axis obstruction or significant bilateral ametropia. Information on ethnicity, birth parameters, and measures of socioeconomic status were collected in questionnaires completed by parents.
Amblyopia.
We included 1422 children aged 30 to 72 months, of whom 27 (1.9%) were found to have amblyopia or suspected amblyopia. Mean spherical equivalent for the amblyopic eyes was +3.57 diopters, with a mean VA of 20/50. Only 3 of the 27 amblyopic children had previous diagnoses or treatments for amblyopia. In regression analysis controlling for age, gender, and ethnicity, amblyopia was significantly associated with hyperopia (odds ratio OR, 15.3; 95% confidence interval CI, 6.5-36.4), astigmatism (OR, 5.7; 95% CI, 2.5-12.7), anisometropia (OR, 27.8; 95% CI, 11.2-69.3), and strabismus (OR, 13.1; 95% CI, 4.3-40.4). There were no significant associations of amblyopia with low birthweight (<2500 g), preterm birth (<37 weeks), maternal smoking, age, gender, ethnicity, or measures of socioeconomic status (all P>0.05).
Amblyopia was found in 1.9% of this Australian preschool sample, which is comparable with prevalence rates reported by other recent studies in preschool children. Refractive errors, particularly significant hyperopia and astigmatism, in addition to anisometropia and strabismus, were the major amblyogenic factors. There was a low amblyopia detection rate in this preschool population, which suggests that different strategies are required to improve current vision screening strategies in preschoolers.
The authors have no proprietary or commercial interest in any of the materials discussed in this article.
ABSTRACT
Oscillating eclipsing Algols (oEAs) are remarkable systems that allow us to determine accurate fundamental stellar parameters (mass, radius) and probe the stellar interiors through ...pulsations. TZ Dra is an oEA system containing a δ Scuti component. To examine particular characteristics of such close systems including pulsations and mass transfer, we present a detailed photometric and spectroscopic study of TZ Dra. With the analysis of high-resolution spectra, the orbital parameters were determined by the radial velocity analysis and the atmospheric parameters were derived for the primary component. The binary modelling and the pulsational frequency analysis was carried out using the Transiting Exoplanet Survey Satellite data set. The H α line profiles show the signature of mass transfer from the cool to the hot binary component. The conclusion of mass transfer/mass-loss in the system was supported by the analysis of the orbital period changes. As a result, it was found that there is $3.52 \times 10^{-9}\, {\rm M}_\odot$ yr−1 mass-loss from the system most probably through the hotspot and stellar winds. Additionally, most pulsation frequencies originating from the primary component were found to be spaced by harmonics of the orbital frequencies in particular, 12 doublets spaced by 2forb were detected from which we infer that this star is a tidally tilted pulsator. A mean p-mode frequency spacing of ≈7.2 d−1 was found as well.
ABSTRACT
Magnetic chemically peculiar stars of the main sequence can present rotational periods as long as many decades. Here we report the results of an observational campaign started in 2001 aimed ...at establishing these very long periods from the variability of the integrated magnetic field modulus, the so-called surface magnetic field Bs, as measured from the Zeeman splitting of the Fe ii 6149.258 Å spectral line. 36 stars have been monitored with various high-resolution spectrographs at different telescopes, totalling 412 newly collected spectra. To improve the phase coverage, we have also exploited all public archives containing high-resolution spectra, many not yet published. On the basis of these new Bs variability curves, we (1) confirm or revisit the periods of 24 stars, (2) extend the lower limits to the periods of HD 55719 (P > 38 yr), HD 165474 (P > 27 yr), and HD 177765 (P > 37 yr), (3) establish for the first time the periods of HD 29578 (P = 10.95 yr), HD 47103 (P = 17.683 d), HD 150562 (P = 5.7 yr), and HD 216018 (P = 34.044 d), and (4) set lower limits to the periods of HD 75445 (P »14 yr), HD 110066 (P » 29 yr), HD 116114 (P > 48 yr), and HD 137949 (P > 27 yr). As to γ Equ, whose period must exceed 90 yr, we point out a clear decrease in the field modulus, the maximum of which coincides within the uncertainties with the minimum of the variation in the integrated longitudinal field.
Tremelimumab (CP-675,206) is a fully human monoclonal antibody binding to cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) on T cells that stimulates the immune system by blocking the ...CTLA4-negative regulatory signal. Combination with standard chemotherapy may strengthen antitumor therapy. This is a phase Ib, multisite, open-label, nonrandomized dose escalation trial evaluating the safety, tolerability, and maximum tolerated dose (MTD) of tremelimumab combined with gemcitabine in patients with metastatic pancreatic cancer.
Gemcitabine (1000 mg/m2 on days 1, 8, and 15 of each 28-day cycles) was administrated with escalating doses of i.v. tremelimumab (6, 10, or 15 mg/kg) on day 1 of each 84-day cycle for a maximum of 4 cycles. The first 18 patients had an initial 4-week gemcitabine-only lead-in period. Dose-limiting toxicities (DLTs) related to tremelimumab were evaluated during the first 6 weeks after the first dose of tremelimumab.
From June 2008 to August 2011, 34 patients were enrolled and received at least one dose of tremelimumab. No DLTs related to tremelimumab were observed at any dose, even when the maximum dose established for tremelimumab (15 mg/kg) was used. Most frequent grade 3/4 toxicities were asthenia (11.8%) and nausea (8.8%). Only one patient had a serious drug-related event (diarrhea with dehydration). The median overall survival was 7.4 months (95% confidence interval 5.8–9.4 months). At the end of treatment, two patients achieved partial response. Both patients received tremelimumab 15-mg/kg group (n = 2/19, 10.5%).
Tremelimumab plus gemcitabine demonstrated a safety and tolerability profile, warranting further study in patients with metastatic pancreatic cancer.
NCT00556023.
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