2,281 research outputs found
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
An automatic procedure to extract galaxy clusters from CRoNaRio catalogs
We present preliminary results of a simple peak finding algorithm applied to
catalogues of galaxies, extracted from the Second Palomar Sky Survey in the
framework of the CRoNaRio project. All previously known Abell and Zwicky
clusters in a test region of 5x5 sq. deg. are recovered and new candidate
clusters are also detected. This algorithm represents an alternative way of
searching for galaxy clusters with respect to that implemented and tested at
Caltech on the same type of data (Gal et al. 1998).Comment: in the proceeding of the XLIII SAIt national conference Mem. Soc.
Astr. It., in pres
A QoE Model for Mulsemedia TV in a Smart Home Environment
The provision to the users of realistic media contents is one of the main goals of future media services. The sense of reality perceived by the user can be enhanced by adding various sensorial effects to the conventional audio-visual content, through the stimulation of the five senses stimulation (sight, hearing, touch, smell and taste), the so-called multi-sensorial media (mulsemedia). To deliver the additional effects within a smart home (SH) environment, custom devices (e.g., air conditioning, lights) providing opportune smart features, are preferred to ad-hoc devices, often deployed in a specific context such as for example in gaming consoles. In the present study, a prototype for a mulsemedia TV application, implemented in a real smart home scenario, allowed the authors to assess the user's Quality of Experience (QoE) through test measurement campaign. The impact of specific sensory effects (i.e., light, airflow, vibration) on the user experience regarding the enhancement of sense of reality, annoyance, and intensity of the effects was investigated through subjective assessment. The need for multi sensorial QoE models is an important challenge for future research in this field, considering the time and cost of subjective quality assessments. Therefore, based on the subjective assessment results, this paper instantiates and validates a parametric QoE model for multi-sensorial TV in a SH scenario which indicates the relationship between the quality of audiovisual contents and user-perceived QoE for sensory effects applications
Perinatal nutrient restriction reduces nephron endowment increasing renal morbidity in adulthood: A review
Perinatal malnutrition has been included among the causes of renal disease in adulthood. Here, we consider the relationships between early supply of specific nutrients (such as protein, fat, vitamins and electrolytes) and renal endowment. Prenatal and postnatal nutrition mismatch is also discussed. In addition, this article presents the role of nutrition of both mothers and pre-term infants on nephron endowment, with final practical considerations. (C) 2010 Elsevier Ireland Ltd. All rights reserved
Prediction of specific biomolecule adsorption on silica surfaces as a function of pH and particle size
Silica nanostructures are biologically available and find wide applications for drug delivery, catalysts, separation processes, and composites. However, specific adsorption of biomolecules on silica surfaces and control in biomimetic synthesis remain largely unpredictable. In this contribution, the variability and control of peptide adsorption on silica nanoparticle surfaces is explained as a function of pH, particle diameter, and peptide electrostatic charge using molecular dynamics simulations with the CHARMM-INTERFACE force field. Adsorption free energies and specific binding residues are analyzed in molecular detail, providing experimentally elusive, atomic-level information on the complex dynamics of aqueous electric double layers in contact with biological molecules. Tunable contributions to adsorption are described in the context of specific silica surface chemistry, including ion pairing, hydrogen bonds, hydrophobic interactions, and conformation effects. Remarkable agreement is found for computed peptide binding as a function of pH and particle size versus experimental adsorption isotherms and zeta-potentials. Representative surface models were built using characterization of the silica surfaces by TEM, SEM, BET, TGA, ζ-potential, and surface titration measurements. The results show that the recently introduced interatomic potentials (Emami et al. Chem. Mater. 2014, 26, 2647) enable computational screening of a limitless number of silica interfaces to predict the binding of drugs, cell receptors, polymers, surfactants, and gases under realistic solution conditions at the scale of 1 to 100 nm. The highly specific binding outcomes underline the significance of the surface chemistry, pH, and topography
The galaxy environment in GAMA G3C groups using the Kilo Degree Survey Data Release 3
We aim to investigate the galaxy environment in GAMA Galaxy Groups Catalogue
(G3C) using a volume-limited galaxy sample from the Kilo Degree Survey Data
Release 3. The k-Nearest Neighbour technique is adapted to take into account
the probability density functions (PDFs) of photometric redshifts in our
calculations. This algorithm was tested on simulated KiDS tiles, showing its
capability of recovering the relation between galaxy colour, luminosity and
local environment. The characterization of the galaxy environment in G3C groups
shows systematically steeper density contrasts for more massive groups. The red
galaxy fraction gradients in these groups is evident for most of group mass
bins. The density contrast of red galaxies is systematically higher at group
centers when compared to blue galaxy ones. In addition, distinct group center
definitions are used to show that our results are insensitive to center
definitions. These results confirm the galaxy evolution scenario which
environmental mechanisms are responsible for a slow quenching process as
galaxies fall into groups and clusters, resulting in a smooth observed colour
gradients in galaxy systems.Comment: 14 pages, Accepted to MNRA
Left atrial trajectory impairment in hypertrophic cardiomyopathy disclosed by geometric morphometrics and parallel transport
The analysis of full Left Atrium (LA) deformation and whole LA deformational trajectory in time has been poorly investigated and, to the best of our knowledge, seldom discussed in patients with Hypertrophic Cardiomyopathy. Therefore, we considered 22 patients with Hypertrophic Cardiomyopathy (HCM) and 46 healthy subjects, investigated them by three-dimensional Speckle Tracking Echocardiography, and studied the derived landmark clouds via Geometric Morphometrics with Parallel Transport. Trajectory shape and trajectory size were different in Controls versus HCM and their classification powers had high AUC (Area Under the Receiving Operator Characteristic Curve) and accuracy. The two trajectories were much different at the transition between LA conduit and booster pump functions. Full shape and deformation analyses with trajectory analysis enabled a straightforward perception of pathophysiological consequences of HCM condition on LA functioning. It might be worthwhile to apply these techniques to look for novel pathophysiological approaches that may better define atrio-ventricular interaction
Photometric validation of a model independent procedure to extract galaxy clusters
By means of CCD photometry in three bands (Gunn g, r, i) we investigate the
existence of 12 candidate clusters extracted via a model independent peak
finding algorithm (\cite{memsait}) from DPOSS data. The derived color-magnitude
diagrams allow us to confirm the physical nature of 9 of the cluster
candidates, and to estimate their photometric redshifts. Of the other
candidates, one is a fortuitous detection of a true cluster at z~0.4, one is a
false detection and the last is undecidable on the basis of the available data.
The accuracy of the photometric redshifts is tested on an additional sample of
8 clusters with known spectroscopic redshifts. Photometric redshifts turn out
to be accurate within z~0.01 (interquartile range).Comment: A&A in pres
A comparison of acute phase proteins and traditional risk factors as markers of combined plaque and intima-media thickness and plaque density in carotid and femoral arteries
AbstractObjectives: to test the hypothesis that some acute phase proteins may be better independent predictors of objective measures of arterial wall impairment than traditional risk factors. Design: cross-sectional study. Materials and Methods: C-reactive protein (CRP), fibrinogen, C3 complement and traditional risk factors were measured in 288 men aged 55-64 years, randomly chosen from the local registry lists. By ultrasound assessment of the bifurcations of carotid and femoral arteries, maximum combined plaque/intima-media thickness (CPIMTmax) and mean plaque density (MPD, in a grey scale from 0 to 255) were also measured. Results: in multivariate analysis only traditional risk factors remained associated with the overall CPIMTmax: smoking (r = 0.35, p < 0.0001), cholesterol (r = 0.23, p = 0.0001), age (r = 0.22, p = 0.0002), glucose (r = 0.18, p = 0.002) and systolic blood pressure (r = 0.13, p = 0.02). However, with regard to carotid disease only, fibrinogen was the strongest covariate of CPIMT (r = 0.18, p = 0.002). The overall MPD was independently associated with CRP (r = 0.25, p = 0.0008), physical activity (r = 0.19, p = 0.009), triglycerides (r = â0.18, p = 0.02) and body mass index (r = 0.15, p = 0.04). CRP was mainly associated with femoral MPD, while triglycerides were the major (inverse) covariate of carotid MPD. Conclusions: traditional risk factors are the main determinants of CPIMTmax, although fibrinogen seems to play a role in carotids. CRP was associated with high density femoral plaques. Finally, no acute phase protein was independently associated with low density, potentially vulnerable, plaques.Eur J Vasc Endovasc Surg 26, 81-87 (2003
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