The Cepheids of NGC1866: A Precise Benchmark for the Extragalactic Distance Scale and Stellar Evolution from Modern UBVI Photometry

We present the analysis of multiband time-series data for a sample of 24 Cepheids in the field of the Large Magellanic Cloud cluster NGC1866. Very accurate BVI VLT photometry is combined with archival UBVI data, covering a large temporal window, to obtain precise mean magnitudes and periods with typical errors of 1-2% and of 1 ppm, respectively. These results represent the first accurate and homogeneous dataset for a substantial sample of Cepheid variables belonging to a cluster and hence sharing common distance, age and original chemical composition. Comparisons of the resulting multiband Period-Luminosity and Wesenheit relations to both empirical and theoretical results for the Large Magellanic Cloud are presented and discussed to derive the distance of the cluster and to constrain the mass-luminosity relation of the Cepheids. The adopted theoretical scenario is also tested by comparison with independent calibrations of the Cepheid Wesenheit zero point based on trigonometric parallaxes and Baade-Wesselink techniques. Our analysis suggests that a mild overshooting and/or a moderate mass loss can affect intermediate-mass stellar evolution in this cluster and gives a distance modulus of 18.50 +- 0.01 mag. The obtained V,I color-magnitude diagram is also analysed and compared with both synthetic models and theoretical isochrones for a range of ages and metallicities and for different efficiencies of core overshooting. As a result, we find that the age of NGC1866 is about 140 Myr, assuming Z = 0.008 and the mild efficiency of overshooting suggested by the comparison with the pulsation models.Comment: 13 pages, 10 figures, accepted in MNRAS (2016 January 14

Impact of distance determinations on Galactic structure. II. Old tracers

Here we review the efforts of a number of recent results that use old tracers to understand the build up of the Galaxy. Details that lead directly to using these old tracers to measure distances are discussed. We concentrate on the following: (1) the structure and evolution of the Galactic bulge and inner Galaxy constrained from the dynamics of individual stars residing therein; (2) the spatial structure of the old Galactic bulge through photometric observations of RR Lyrae-type stars; (3) the three\--dimensional structure, stellar density, mass, chemical composition, and age of the Milky Way bulge as traced by its old stellar populations; (4) an overview of RR Lyrae stars known in the ultra-faint dwarfs and their relation to the Galactic halo; and (5) different approaches for estimating absolute and relative cluster ages.Comment: Review article, 80 pages (25 figures); Space Science Reviews, in press (chapter of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

Computed tomography findings of pneumatosis and portomesenteric venous gas in acute bowel ischemia.

BACKGROUND: To use more representative sample size to evaluate whether computed tomography (CT) scan evidence of the concomitant presence of pneumatosis and portomesenteric venous gas is a predictor of transmural bowel necrosis. METHODS: Data from 208 patients who were referred for a diagnosis of bowel ischemia were retrospectively reviewed. Only patients who underwent a surgical intervention following a diagnosis of bowel ischemia who also had a post-operative histological confirmation of such a diagnosis were included. Patients were split into two groups according to the presence of histological evidence of transmural bowel ischemia (case group) or partial bowel ischemia (control group). CT images were reviewed for findings of ischemia, including mural thickening, pneumatosis, bowel distension, portomesenteric venous gas and arterial or venous thrombi. RESULTS: A total of 248 subjects who underwent surgery for bowel ischemia were identified. Among the 208 subjects enrolled in our study, transmural bowel necrosis was identified in 121 subjects (case group), and partial bowel necrosis was identified in 87 subjects (control group). Based on CT findings, including mural thickening, bowel distension, pneumatosis, pneumatosis plus portomesenteric venous gas and presence of thrombi or emboli, there were no significant differences between the case and control groups. The concomitant presence of pneumatosis and porto-mesenteric venous gas showed an odds ratio of 1.95 (95%CI: 0.491-7.775, P = 0.342) for the presence of transmural necrosis. The presence of pneumatosis plus porto-mesenteric venous gas exhibited good specificity (83%) but low sensitivity (17%) in the identification of transmural bowel infarction. Accordingly, the positive and negative predictive values were 60% and 17%, respectively. CONCLUSION: Although pneumatosis plus porto-mesenteric venous gas is associated with bowel ischemia, we have demonstrated that their co-occurrence cannot be used as diagnostic signs of transmural necrosis

Carbon star survey in the Local Group. VII. NGC 3109 a galaxy without a stellar halo

We present a CFH12K wide field survey of the carbon star population in and around NGC 3109. Carbon stars, the brightest members of the intermediate-age population, were found nearly exclusively in and near the disk of NGC 3109, ruling out the existence of an extensive intermediate-age halo like the one found in NGC 6822. Over 400 carbon stars identified have = -4.71, confirming the nearly universality of mean magnitude of C star populations in Local Group galaxies. Star counts over the field reveal that NGC 3109 is a truncated disk shaped galaxy without an extensive stellar halo. The minor axis star counts reach the foreground density between 4' and 5', a distance that can be explained by an inclined disk rather than a spheroidal halo. We calculate a global C/M ratio of 1.75 +/- 0.20, a value expected for such a metal poor galaxy.Comment: Accepted in Astronomy and Astrophysic

The Carina Project. VI. The helium burning variable stars

We present new optical (BVI) time-series data for the evolved variable stars in the Carina dwarf spheroidal galaxy. The quality of the data and the observing strategy allowed us to identify 14 new variable stars. Eight out of the 14 are RR Lyrae (RRL) stars, four are Anomalous Cepheids (ACs) and two are geometrical variables. Comparison of the period distribution for the entire sample of RRLs with similar distributions in nearby dSphs and in the Large Magellanic Cloud indicates that the old stellar populations in these systems share similar properties. This finding is also supported by the RRL distribution in the Bailey diagram. On the other hand, the period distribution and the Bailey diagram of ACs display significant differences among the above stellar systems. This evidence suggests that the properties of intermediate-age stellar populations might be affected both by environmental effects and structural parameters. We use the BV Period--Wesenheit (PW) relation of RRLs together with evolutionary prescriptions and find a true distance modulus of 20.09+/-0.07(intrinsic)+/-0.1(statistical) mag that agrees quite well with similar estimates available in the literature. We identified four peculiar variables. Taking into account their position in the Bailey diagram and in the BV PW relation, two of them (V14, V149) appear to be candidate ACs, while two (V158, V182) might be peculiar RRLs. In particular, the variable V158 has a period and a V-band amplitude very similar to the low-mass RRL ---RRLR-02792---recently identified by Pietrzynski at al. (2012) in the Galactic bulge.Comment: Accepted for publication in ApJ, publication date September 20, 2013. 31 pages, 7 figure, 3 tables. Figs. 3 and 4 corrected, references added, minor correction

Haemostatic and fibrinolytic changes in obese subjects undergoing bariatric surgery: the effect of different surgical procedures.

Background Little is known about effects of different bariatric surgery procedures on haemostatic and fibrinolytic parameters. Material and methods Consecutive obese subjects undergoing gastric bypass (GBP) or sleeve gastrectomy (SG) were enrolled. In all patients, levels of haemostatic factors (FII, FVII, FVIII, FIX, FX, vWF, fibrinogen), fibrinolytic variables (PAI-1, t-PA and D-dimer) and natural anticoagulants (AT, protein C and protein S) were evaluated before and 2 months after surgery. Results A total of 77 GBP and 79 SG subjects completed the study. At baseline no difference in coagulation parameters was found between the two groups. After both GBP and SG, subjects showed significant changes in haemostatic and fibrinolytic variables and in natural anticoagulant levels. The Δ% changes in FVII, FVIII, FIX, vWF, fibrinogen, D-dimer, protein C and protein S levels were significantly higher in subjects who underwent GBP than in those who underwent SG. Multivariate analysis confirmed that GBP was a predictor of higher Δ% changes in FVII (β=0.268, p=0.010), protein C (β=0.274, p=0.003) and protein S (β=0.297, p<0.001), but not in all the other variables. Following coagulation factor reduction, 31 subjects (25.9% of GBP and 13.9% of SG; p=0.044) showed overt FVII deficiency; protein C deficiency was reported by 34 subjects (32.5% of GBP vs 11.4% of SG, p=0.033) and protein S deficiency by 39 (37.6% of GBP vs 12.6% of SG, p=0.009). Multivariate analyses showed that GBP was associated with an increased risk of deficiency of FVII (OR: 3.64; 95% CI: 1.73–7.64, p=0.001), protein C (OR: 4.319; 95% CI: 1.33–13.9, p=0.015) and protein S (OR: 5.50; 95% CI: 1.71–17.7, p=0.004). Discussion GBP is associated with an increased risk of post-operative deficiency in some vitamin K-dependent coagulation factors. Whereas such deficiency is too weak to cause bleeding, it is significant enough to increase the risk of thrombosis

The Carina Project IX: on Hydrogen and helium burning variables

We present new multi-band (UBVI) time-series data of helium burning variables in the Carina dwarf spheroidal galaxy. The current sample includes 92 RR Lyrae-six of them are new identifications-and 20 Anomalous Cepheids, one of which is new identification. The analysis of the Bailey diagram shows that the luminosity amplitude of the first overtone component in double-mode variables is located along the long-period tail of regular first overtone variables, while the fundamental component is located along the short-period tale of regular fundamental variables. This evidence further supports the transitional nature of these objects. Moreover, the distribution of Carina double-mode variables in the Petersen diagram (P_1/P_0 vs P_0) is similar to metal-poor globulars (M15, M68), to the dwarf spheroidal Draco and to the Galactic Halo. This suggests that the Carina old stellar population is metal-poor and affected by a small spread in metallicity. We use trigonometric parallaxes for five field RR Lyrae stars to provide an independent estimate of the Carina distance using the observed reddening free Period--Wesenheit [PW, (BV)] relation. Theory and observations indicate that this diagnostic is independent of metallicity. We found a true distance modulus of \mu=20.01\pm0.02 (standard error of the mean) \pm0.05 (standard deviation) mag. We also provided independent estimates of the Carina true distance modulus using four predicted PW relations (BV, BI, VI, BVI) and we found: \mu=(20.08\pm0.007\pm0.07) mag, \mu=(20.06\pm0.006\pm0.06) mag, \mu=(20.07\pm0.008\pm0.08) mag and \mu=(20.06\pm0.006\pm0.06) mag. Finally, we identified more than 100 new SX Phoenicis stars that together with those already known in the literature (340) make Carina a fundamental laboratory to constrain the evolutionary and pulsation properties of these transitional variables.Comment: 44 pages, 13 tables, 13 figures, Accepted for publication in Ap

Flotac and Mini-Flotac for uro-microscopic diagnosis of Capillaria plica (syn. Pearsonema plica) in dogs

Background: Capillaria plica (syn. Pearsonema plica) is a nematode that resides in the urinary bladder and rarely in ureters or in the kidney pelvis of various carnivores, especially foxes and dogs. Urine sedimentation technique is actually the only diagnostic tool that permits the identification of C. plica eggs, but its sensitivity is low and when an infection is suspected (or when it is necessary to confirm treatment efficacy) more than one examination of urine sediment should be performed. The present paper reports a clinical case of natural C. plica infection in a dog from southern Italy. In addition, two new techniques, FLOTAC and Mini-FLOTAC, were used for the diagnosis of C. plica in dog urine and compared with the technique of sedimentation. Results: Using FLOTAC with fresh urine and sodium chloride as flotation solution, were obtained the best results for the diagnosis of C. plica in dog urine in term of eggs counted (mean eggs per 10 ml of urine = 70.3 FLOTAC vs 40.3 Mini FLOTAC vs 32.8 sedimentation) and coefficient of variation (CV%) (6.2 FLOTAC vs 13.4 Mini-FLOTAC vs 32.9 sedimentation). Conclusions: The FLOTAC was the more sensitive method, but also the Mini-FLOTAC could be a valid alternative diagnostic method because gave better results than the classical sedimentation and can be used in place of the FLOTAC in laboratories where the centrifugation step cannot be performed. © 2014 Maurelli et al.; licensee BioMed Central Ltd