Models for the lithium abundances of multiple populations in globular clusters and the possible role of the Big Bang lithium

Globular cluster stars show chemical abundance patterns typical of hot-CNO processing. Lithium is easily destroyed by proton capture in stellar environments, so its abundance may be crucial to discriminate among different models proposed to account for multiple populations. In order to reproduce the observed O-Na anticorrelation and other patterns typical of multiple populations, the formation of second generation stars must occur from the nuclearly processed stellar ejecta, responsible of the chemical anomalies, diluted with pristine gas having the composition of first generation stars. The lithium abundance in the unprocessed gas -which is very likely to be equal to the lithium abundance emerging from the Big Bang- affects the lithium chemical patterns among the cluster stars. This paper focuses on a scenario in which processed gas is provided by asymptotic giant branch (AGB) stars. We examine the predictions of this scenario for the lithium abundances of multiple populations. We study the role of the non-negligible lithium abundance in the ejecta of massive AGB (A(Li)~2), and, at the same time, we explore how our models can constrain the extremely large ---and very model dependent--- lithium yields predicted by recent super--AGB models. We show that the super--AGB yields may be tested by examining the lithium abundances in a large set of blue main sequence stars in wCen and/or NGC2808. In addition, we examine the different model results obtained by assuming for the pristine gas either the Big Bang abundance predicted by the standard models (A(Li)=2.6-2.7), or the abundance detected at the surface of population II stars (A(Li)=2.2-2.3). Once a chemical model is well constrained, the O--Li distribution could perhaps be used to shed light on the primordial lithium abundance

Classification tree to analyze factors connected with post operative complications of cataract surgery in a teaching hospital

Background: Artificial intelligence (AI) is becoming ever more frequently applied in medicine and, consequently, also in ophthalmology to improve both the quality of work for physicians and the quality of care for patients. The aim of this study is to use AI, in particular classification tree, for the evaluation of both ocular and systemic features involved in the onset of complications due to cataract surgery in a teaching hospital. Methods: The charts of 1392 eyes of 1392 patients, with a mean age of 71.3 8.2 years old, were reviewed to collect the ocular and systemic data before, during and after cataract surgery, including post-operative complications. All these data were processed by a classification tree algorithm, producing more than 260 million simulations, aiming to develop a predictive model. Results: Postoperative complications were observed in 168 patients. According to the AI analysis, the pre-operative characteristics involved in the insurgence of complications were: ocular comorbidities, lower visual acuity, higher astigmatism and intra-operative complications. Conclusions: Artificial intelligence application may be an interesting tool in the physician’s hands to develop customized algorithms that can, in advance, define the post-operative complication risk. This may help in improving both the quality and the outcomes of the surgery as well as in preventing patient dissatisfaction

An extremely primitive halo star

The early Universe had a chemical composition consisting of hydrogen, helium and traces of lithium1, almost all other elements were created in stars and supernovae. The mass fraction, Z, of elements more massive than helium, is called "metallicity". A number of very metal poor stars have been found some of which, while having a low iron abundance, are rich in carbon, nitrogen and oxygen. For theoretical reasons and because of an observed absence of stars with metallicities lower than Z=1.5E-5, it has been suggested that low mass stars (M<0.8M\odot, the ones that survive to the present day) cannot form until the interstellar medium has been enriched above a critical value, estimated to lie in the range 1.5E-8\leqZ\leq1.5E-6, although competing theories claiming the contrary do exist. Here we report the chemical composition of a star with a very low Z\leq6.9E-7 (4.5E-5 of that of the Sun) and a chemical pattern typical of classical extremely metal poor stars, meaning without the enrichment of carbon, nitrogen and oxygen. This shows that low mass stars can be formed at very low metallicity. Lithium is not detected, suggesting a low metallicity extension of the previously observed trend in lithium depletion. Lithium depletion implies that the stellar material must have experienced temperatures above two million K in its history, which points to rather particular formation condition or internal mixing process, for low Z stars.Comment: Published on Nature, 2011 Volume 477, Issue 7362, pp. 67-6

VizieR Online Data Catalog: Abundances of 3 CEMP stars (Bonifacio+, 2015)

We analyse both X-Shooter and UVES spectra acquired at the VLT. We used a traditional abundance analysis based on OSMARCS 1D Local Thermodynamic Equilibrium (LTE) model atmospheres and the TURBOSPECTRUM line formation code.(2 data files)

Retrospective volume analysis of bone remodeling after tooth extraction with and without deproteinized bovine bone mineral insertion

Objectives: The aim of the study was to analyze volume changes of post-extractive sockets grafted with or without deproteinized bovine bone mineral (DBBM) and a resorbable barrier. Materials and methods: This retrospective analysis utilized patients who had undergone tooth extraction. Sites, one per patient, were allocated to two groups: post-extractive non-grafted sockets (NG) and post-extractive grafted sockets with DBBM and resorbable barrier insertion (G). Maximal primary soft tissue closure was sought for both procedures. Before extraction and 6 months later, three-dimensional features of the sockets (linear indexes, areas, and volumes) and outcome variables at 6 months (volume- and surface changes) were acquired through computer tomography scans. Intra- and inter-group comparisons of the outcome variables were performed. Nonparametric tests were applied with a level of significance set at P < 0.01. Results: Twenty-four sites, 9 grafted and 15 ungrafted, were enrolled. Between baseline and the 6-month evaluation, significant bone volume loss, superior surface shrinkage, and height reduction were registered for the G (72 mm3, 76 mm2, and 0.5 mm, respectively) and the NG group (274 mm3, 87 mm2, and 1.8 mm, respectively) with all P-values â¤Â 0.0039. A significant difference, regarding the percentage of the volume change, was registered between the two procedures with a volume loss of 9.9% for the grafted sockets and 34.8% for the ungrafted ones (P-value = 0.0073). Conclusion: Grafting of the sockets with DBBM and a resorbable barrier insertion seemed to reduce negative osseous remodeling in the short term when compared to that of the ungrafted sockets

Evaluation of volumetric dimensional changes in posterior extraction sites with and without ARP using a novel imaging device

Background: Alveolar ridge volume loss may be minimized when postextraction sockets are filled by bone substitutes. Purpose: The aim of the study was to measure the effect of alveolar ridge preservation (ARP) in maintaining the external contour of the ridge after fresh socket grafting with or without particulate anorganic bovine bone mineral (BBM) and resorbable barrier covering. Materials and methods: In the present controlled study, patients subjected to single-tooth extraction were allocated to 2 groups: postextraction sockets grafted with bovine bone mineral (bbm), and naturally healing sockets (nat). Before and at 5 months following tooth extraction, plaster cast contours of the sockets were acquired by means of an optical scanner; the 2 contours of each patient underwent voxelization and fusion using a matrix elaborator. Outcome variables at 5 months (volumetric, surface, and linear changes) were measured in digital fused plaster casts with a dental scan software analyzing a volume of interest ranging from residual papilla to 10 mm toward the apical point. Intra- and inter-group pair-wise variables' comparisons were conducted. Level of significance was set at 0.05. Results: Twenty-four sites were enrolled: 12 ARP and 12 naturally healed. Five-month percentage of volume loss of the bbm-group (21.7% ± 7.4%) was significantly lower (Ps <.0003) than that of the naturally healing group (38.8% ± 7.9%). When tooth position was investigated, volume loss in percentage registered a significantly better (P values â\u89¤.0485) behavior in molars (Î\u94V% = â\u88\u9219.1% ± 6.5% and Î\u94V% = â\u88\u9235.6% ± 7.6%, respectively, for bbm and nat) than that in premolars (Î\u94V% = â\u88\u9226.9% ± 7.2% and Î\u94V% = â\u88\u9245.1% ± 4.2%, respectively, for bbm and nat), in both the preserved and naturally healing groups. Conclusion: The dimensional loss in postextraction sockets grafted with anorganic bovine bone substitute and covered by a resorbable collagen barrier was lower than that of the naturally healing sites. However, ridge preservation was able to maintain almost 80% of the pristine bone