Morphology of low-redshift compact galaxy clusters I. Shapes and radial profiles

The morphology of clusters of galaxies may be described with a set of parameters which contain information about the formation and evolutionary history of these systems. In this paper we present a preliminary study of the morphological parameters of a sample of 28 compact Abell clusters extracted from DPOSS data. The morphology of galaxy clusters is parameterized by their apparent ellipticity, position angle of the major axis, centre coordinates, core radius and beta-model power law index. Our procedure provides estimates of these parameters by simultaneously fitting them all, overcoming some of the difficulties induced by sparse data and low number statistics typical of this kind of analysis. The cluster parameters were fitted in a 3 x 3 h^-2 sqMpc region, measuring the background in a 2 <R< 2.5 h^-1Mpc annulus. We also explore the correlations between shape and profile parameters and other cluster properties. One third of this compact cluster sample has core radii smaller than 50 h^-1 kpc, i.e. near the limit that our data allow us to resolve, possibly consistent with cusped models. The remaining clusters span a broad range of core radii up to 750 h^-1 kpc. More than 80 per cent of this sample has ellipticity higher than 0.2. The alignment between the cluster and the major axis of the dominant galaxy is confirmed, while no correlation is observed with other bright cluster members. No significant correlation is found between cluster richness and ellipticity. Instead, cluster richness is found to correlate, albeit with large scatter, with the cluster core radius.[abridged]Comment: 23 pages, 17 figures, accepted for publication in MNRAS. Full paper including full resolution figures 2 and 9 at http://www.eso.org/~vstrazzu/P/ME1030fv.pd

Not smoking is associated with lower risk of hypertension: results of the Olivetti Heart Study.

Few epidemiological investigations evaluated the role of smoking cessation on blood pressure (BP), and the results are not univocal. Therefore, the aim of this study was to assess the effect of smoking cessation on the risk to develop hypertension (HPT) and on BP values. METHODS: This longitudinal study, with a follow-up period of 8 years, included the participants of the Olivetti Heart Study. Participants were 430 untreated normotensive non-diabetic men with normal renal function, examined twice in 1994-95 and in 2002-04. The sample included current smokers (S, n = 212), former smokers (ES, n = 145) and never smokers (NS, n = 73) at baseline. RESULTS: Basal body mass index (BMI), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were significantly higher in ES than in S (ES vs. S; BMI: 27.0 ± 2.5 vs. 26.1 ± 2.9 kg/m(2); P < 0.01; SBP/DBP: 121.2 ± 9.3/80.0 ± 5.8 vs. 19.1 ± 9.9/77.4 ± 6.7 mm Hg; P < 0.05; M ± SD). After 8 years of follow-up, BP changes (Δ) were significantly lower in ES than in S (ΔSBP/DBP: 12.6 ± 13.4/7.9 ± 8.1 vs. 16.0 ± 14.9/10.3 ± 10.1 mm Hg; P < 0.05; M ± SD), also after adjustment for potential confounders. Moreover, at the last examination, the overall HPT prevalence was 33%, with lower values in ES than in S (25 vs. 38%, P = 0.01). After accounting for age, BP and BMI at baseline, and changes in smoking habit over the 8-year period, ES still had significant lower risk of HPT than S (odds ratio 0.30, 95% confidence interval 0.15-0.58; P < 0.01). CONCLUSIONS: In this sample of healthy men, smoking cessation was associated with lower BP increment and minor HPT risk, independently of potential confounders

The Red Sequence of High-Redshift Clusters: a Comparison with Cosmological Galaxy Formation Models

We compare the results from a semi-analytic model of galaxy formation with spectro-photometric observations of distant galaxy clusters observed in the range 0.8< z< 1.3. We investigate the properties of their red sequence (RS) galaxies and compare them with those of the field at the same redshift. In our model we find that i) a well-defined, narrow RS is obtained already by z= 1.2; this is found to be more populated than the field RS, analogously to what observed and predicted at z=0; ii) the predicted U-V rest-frame colors and scatter of the cluster RS at z=1.2 have average values of 1 and 0.15 respectively, with a cluster-to-cluster variance of 0.2 and 0.06, respectively. The scatter of the RS of cluster galaxies is around 5 times smaller than the corresponding field value; iii) when the RS galaxies are considered, the mass growth histories of field and cluster galaxies at z=1.2 are similar, with 90 % of the stellar mass of RS galaxies at z=1.2 already formed at cosmic times t=2.5 Gyr, and 50 % at t=1 Gyr; v) the predicted distribution of stellar ages of RS galaxies at z=1.2 peaks at 3.7 Gyr for both cluster and field populations; however, for the latter the distribution is significantly skewed toward lower ages. When compared with observations, the above findings show an overall consistency, although the average value 0.07 of the observed cluster RS scatter (U-V colors) at z=1.2 is smaller than the corresponding model central value. We discuss the physical origin and the significance of the above results in the framework of cosmological galaxy formation.Comment: 14 pages, accepted for publication in ApJ. Updated one referenc

Atrial natriuretic peptide (ANP) gene promoter variant and increased susceptibility to early development of hypertension in humans.

Previous evidence supports a role of atrial natriuretic peptide (ANP) as a candidate gene for hypertension. We characterized an ANP gene promoter variant, which has been associated with lower peptide levels, in a sample of young male subjects from Southern Italy (n=395, mean age=35.2+/-2 years) followed up for 28 years. In this cohort, the ANP gene variant was associated with early blood pressure increase and predisposition to develop hypertension