175 research outputs found

    Lithium factories in the Galaxy: novae and AGB stars

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    We review the state of the art in modelling lithium production, through the Cameron-Fowler mechanism, in two stellar sites: during nova explosions and in the envelopes of massive asymptotic giant branch (AGB) stars. We also show preliminary results concerning the computation of lithium yields from super-AGBs, and suggest that super-AGBs of metallicity close to solar may be the most important galactic lithium producers. Finally, we discuss how lithium abundances may help to understand the modalities of formation of the "second generation" stars in globular clusters.Comment: invited review presented at IAU Symposium 267 "Light Elements in the Universe", Geneva, Switzerland, Nov. 9-13 2009, in pres

    Triggers for atrial fibrillation. the role of anxiety

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    Atrial fibrillation (AF) is the most widely recognized arrhythmia. Systemic arterial hypertension, diabetes, obesity, heart failure, and valvular heart diseases are major risk factors for the onset and progression of AF. Various studies have emphasized the augmented anxiety rate among AF patients due to the poor quality of life; however, little information is known about the possibility of triggering atrial fibrillation by anxiety. +e present review sought to underline the possible pathophysiological association between AF and anxiety disorders and suggests that anxiety can be an independent risk factor for AF, acting as atrigger, creating an arrhythmogenic substrate, and modulating the autonomic nervous system.+e awareness of the role of anxietydisorders as a risk factor for AF may lead to the development of new clinical strategies for the management of AF

    Chemosensitivity in the Sea Urchin Paracentrotus lividus (Echinodermata: Echinoidea) to Food-Related Compounds: An Innovative Behavioral Bioassay

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    Like other animals, echinoderms rely on chemical senses to detect and localize food resources. Here, we evaluate the chemical sensitivity of the sea urchin Paracentrotus lividus to a number of stimuli possibly related to food, such as a few sugars, compared to the blue-green algae Spirulina (Arthrospira platensis). To do this we developed a simple, innovative method based on the recording of “urchinograms” estimating the movements of spines, pedicellariae, tube feet, and eventually of the whole sea urchin, in response to chemicals, while keeping both the whole animal and the stimulus in their natural environment, underwater. Our results show that Spirulina is a highly stimulating compound for the sea urchin, by acting in a dose-dependent manner. The animals resulted also sensitive, even if to a lesser extent, to some sugars, such as the monosaccharide glucose, but not to its isomer fructose, while among disaccharides, they sensed cellobiose, but not sucrose or trehalose. From an applied point of view, any insight into the chemical sensitivity of sea urchins toward potential food-related compounds may lead to the discovery of key chemicals that would help improve the efficiency and reduce the costs of dietary substrates for optimization of intensive rearing strategies. Although this method has been developed for P. lividus, it will be suitable to evaluate the chemical sensitivity of other echinoderms and other marine invertebrates characterized by low mobility

    Blue-Green Algae as Stimulating and Attractive Feeding Substrates for a Mediterranean Commercial Sea Urchin Species, Paracentrotus lividus

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    Sea urchins rely on chemical senses to localize suitable food resources, therefore representing model species for chemosensory studies. In the present study, we investigated the chemical sensitivity of the Mediterranean sea urchin Paracentrotus lividus to the blue-green alga Aphanizomenon flos-aquae, namely "Klamath", and to a few amino acids chosen from the biochemical composition of the same algae. To this end, we used the "urchinogram" method, which estimates the movement rate of the sea urchins in response to chemicals. Our results showed that Klamath represents a strong chemical stimulus for P. lividus as it elicits an overall movement of spines, pedicellariae, and tube feet coupled, in some cases, to a coordinated locomotion of the animals. Sea urchins also displayed a sensitivity, even if to a lesser extent, to leucine, threonine, arginine, and proline, thus implying that the amino acids contained in Klamath may account, at least in part, for the stimulating effects exerted by the whole algae. Additionally, our results show that Klamath, as well as spirulina, another blue-green alga with high nutritional value, is very attractive for this sea urchin species. These findings gain further importance considering the potential profit of echinoderms for commercial consumers and their growing role in aquaculture. Klamath and spirulina combine high nutritional profiles with attractive and stimulating abilities and may be considered potential valuable feed supplements in sea urchin aquaculture

    The integration of 3D modeling and simulation to determine the energy potential of low-temperature geothermal systems in the Pisa (Italy) sedimentary plain

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    Shallow, low-temperature geothermal resources can significantly reduce the environmental impact of heating and cooling. Based on a replicable standard workflow for three-dimensional (3D) geothermal modeling, an approach to the assessment of geothermal energy potential is proposed and applied to the young sedimentary basin of Pisa (north Tuscany, Italy), starting from the development of a geothermal geodatabase, with collated geological, stratigraphic, hydrogeological, geophysical and thermal data. The contents of the spatial database are integrated and processed using software for geological and geothermal modeling. The models are calibrated using borehole data. Model outputs are visualized as three-dimensional reconstructions of the subsoil units, their volumes and depths, the hydrogeological framework, and the distribution of subsoil temperatures and geothermal properties. The resulting deep knowledge of subsoil geology would facilitate the deployment of geothermal heat pump technology, site selection for well doublets (for open-loop systems), or vertical heat exchangers (for closed-loop systems). The reconstructed geological-hydrogeological models and the geothermal numerical simulations performed help to define the limits of sustainable utilization of an area's geothermal potential

    Effective erythropoiesis and HbF reactivation induced by kit ligand in β-thalassemia

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    In human β-thalassemia, the imbalance between α- and non–α-globin chains causes ineffective erythropoiesis, hemolysis, and anemia: this condition is effectively treated by an enhanced level of fetal hemoglobin (HbF). In spite of extensive studies on pharmacologic induction of HbF synthesis, clinical trials based on HbF reactivation in β-thalassemia produced inconsistent results. Here, we investigated the in vitro response of β-thalassemic erythroid progenitors to kit ligand (KL) in terms of HbF reactivation, stimulation of effective erythropoiesis, and inhibition of apoptosis. In unilineage erythroid cultures of 20 patients with intermedia or major β-thalassemia, addition of KL, alone or combined with dexamethasone (Dex), remarkably stimulated cell proliferation (3-4 logs more than control cultures), while decreasing the percentage of apoptotic and dyserythropoietic cells (<5%). More important, in both thalassemic groups, addition of KL or KL plus Dex induced a marked increase of γ-globin synthesis, thus reaching HbF levels 3-fold higher than in con-trol cultures (eg, from 27% to 75% or 81%, respectively, in β-thalassemia major). These studies indicate that in β-thalassemia, KL, alone or combined with Dex, induces an expansion of effective erythropoiesis and the reactivation of γ-globin genes up to fetal levels and may hence be considered as a potential therapeutic agent for this disease

    A new era of fine structure constant measurements at high redshift

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    New observations of the quasar HE0515-4414 have been made using the HARPS spectrograph on the ESO 3.6m telescope, aided by the Laser Frequency Comb (LFC). We present three important advances for α\alpha measurements in quasar absorption spectra from these observations. Firstly, the data have been wavelength calibrated using LFC and ThAr methods. The LFC wavelength calibration residuals are six times smaller than when using the standard ThAr calibration. We give a direct comparison between α\alpha measurements made using the two methods. Secondly, spectral modelling was performed using Artificial Intelligence (fully automated, all human bias eliminated), including a temperature parameter for each absorption component. Thirdly, in contrast to previous work, additional model parameters were assigned to measure α\alpha for each individual absorption component. The increase in statistical uncertainty from the larger number of model parameters is small and the method allows a substantial advantage; outliers that would otherwise contribute a significant systematic, possibly corrupting the entire measurement, are identified and removed, permitting a more robust overall result. The zabs=1.15z_{abs} = 1.15 absorption system along the HE0515-4414 sightline yields 40 new α\alpha measurements. We constrain spatial fluctuations in α\alpha to be Δα/α9×105\Delta\alpha/\alpha \leq 9 \times 10^{-5} on scales 20  kms1\approx 20\;{\rm km\,s}^{-1}, corresponding to 25  \approx25\;kpc if the zabs=1.15z_{abs} = 1.15 system arises in a 1  1\;Mpc cluster. Collectively, the 40 measurements yield Δα/α=0.27±2.41×106\Delta\alpha/\alpha=-0.27\pm2.41\times10^{-6}, consistent with no variation.Comment: Published in MNRAS, 500 1 1. 10 pages, 7 figures. Online supplementary material is available upon reques

    Sialendoscopy for salivary stones: principles, technical skills and therapeutic experience

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    La scialoadenite cronica ostruttiva rappresenta una delle più frequenti patologie non-neoplastiche delle ghiandole salivari e la scialoendoscopia è sempre più utilizzata nella sua diagnosi e nel suo trattamento, associata o meno con la litotripsia laser. La scialoendoscopia può essere inoltre associata ad approcci esterni mini-invasivi nelle litiasi troppo voluminose per essere rimosse con un approccio unicamente endoscopico. Il presente articolo riporta l’esperienza delle Cliniche Otorinolaringoiatriche dell’Ospedale Sant’Orsola-Malpighi di Bologna e dell’Azienda Ospedaliero Universitaria di Cagliari, Italia. È stata eseguita un’analisi retrospettiva su 48 pazienti (26 femmine, 22 maschi; età media di 45,3 anni; range 8-83 anni) trattati per patologia cronica ostruttiva delle ghiandole salivari maggiori mediante procedure chirurgiche endoscopiche o combinate da novembre 2010 ad aprile 2016 presso l’Azienda-Ospedaliero-Universitaria di Cagliari. I risultati dell’Ospedale Sant’Orsola-Malpighi di Bologna erano stati precedentemente pubblicati. Gli aspetti tecnici della scialoendoscopia sono stati accuratamente descritti. I pazienti trattati presso l’Azienda Ospedaliero Universitaria di Cagliari presentavano una patologia unilaterale in 40 casi e bilaterale in 8 casi; sono state trattate 56 ghiandole salivari maggiori (22 sottomandibolari e 34 parotidi). 5 pazienti sono stati sottoposti a scialoendoscopia bilaterale per parotite ricorrente giovanile, 10 per patologia ostruttiva non litiasica e 33 (68,75%) presentavano calcoli salivari (1 paziente presentava una litiasi parotidea bilaterale). Solo 8 pazienti sono stati sottoposti a scialectomia radicale per via esterna (5 scialectomie sottomandibolare e 3 parotidectomie). La chirurgia conservativa nei pazienti con scialoadenite cronica ostruttiva appare efficace e può essere realizzata mediante un approccio puramente endoscopico o combinato, con un’alta percentuale di successo. La procedura richiede una strumentazione adeguata e deve essere eseguita da un chirurgo esperto, che abbia svolto un training specifico scialoendoscopico, in modo da evitare le possibili complicanze maggiori e minori. La scialectomia tradizionale rappresenta la “extrema ratio”, limitata nei casi in cui un approccio conservativo sia risultato inefficace o controindicato.Obstructive sialadenitis is the most common non-neoplastic disease of the salivary glands, and sialendoscopy is increasingly used in both diagnosis and treatment, associated in selected cases with endoscopic laser lithotripsy. Sialendoscopy is also used for combined minimally invasive external and endoscopic approaches in patients with larger and proximal stones that would require excessively long laser procedures. The present paper reports on the technical experience from the Ear, Nose and Throat Unit of the Sant'Orsola-Malpighi Hospital of Bologna, and from the Department of Otorhinolaryngology of the University Hospital of Cagliari, Italy, including the retrospective analysis of the endoscopic and endoscopic assisted procedures performed on 48 patients (26 females and 22 males; median age 45.3; range 8-83 years) treated for chronic obstructive sialadenitis at the University Hospital of Cagliari from November 2010 to April 2016. The results from the Sant'Orsola-Malpighi Hospital of Bologna have been previously published. The technical aspects of sialendoscopy are carefully described. The retrospective analysis of the University Hospital of Cagliari shows that the disease was unilateral in 40 patients and bilateral in 8; a total of 56 major salivary glands were treated (22 submandibular glands and 34 parotids). Five patients underwent bilateral sialendoscopy for juvenile recurrent parotitis. 10 patients were treated for non-lithiasic obstructive disease. In 33 patients (68.75%) the obstruction was caused by salivary stones (bilateral parotid lithiasis in 1 case). Only 8 patients needed a sialectomy (5 submandibular glands and 3 parotids). The conservative approach to obstructive sialadenitis is feasible and can be performed either purely endoscopically or in a combined modality, with a high percentage of success. The procedure must be performed with dedicated instrumentation by a skilled surgeon after proper training since minor to major complications can be encountered. Sialectomy should be the "extrema ratio" after failure of a conservative approach
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