2,859 research outputs found
Ab-initio calculation of the binding energy with the Hybrid Multideterminant scheme
We perform an ab-initio calculation for the binding energy of using
the CD-Bonn 2000 NN potential renormalized with the Lee-Suzuki method. The
many-body approach to the problem is the Hybrid Multideterminant method. The
results indicate a binding energy of about , within a few hundreds KeV
uncertainty. The center of mass diagnostics are also discussed.Comment: 18 pages with 3 figures. More calculations added, to be published in
EPJ
Scaling relations of the colour-detected cluster RzCS 052 at z=1.016 and of some other high redshift clusters
We report on the discovery of the z=1.016 cluster RzCS 052 using a modified
red sequence method, followup spectroscopy and X-ray imaging. This cluster has
a velocity dispersion of 710+-150 km/s, a virial mass of 4.0e14 Msol (based on
21 spectroscopically confirmed members) and an X-ray luminosity of (0.68+-
0.47)e44 ergs/s in the [1-4] keV band. This optically selected cluster appears
to be of richness class 3 and to follow the known L_X-sigma_v relation for high
redshift X-ray selected clusters. Using these data, we find that the halo
occupation number for this cluster is only marginally consistent with what
expected assuming a self-similar evolution of cluster scaling relations,
suggesting perhaps a break of them at z~1. We also rule out a strong galaxy
merging activity between z=1 and today. Finally, we present a Bayesian approach
to measuring cluster velocity dispersions and X-ray luminosities in the
presence of a background: we critically reanalyze recent claims for X-ray
underluminous clusters using these techniques and find that the clusters can be
accommodated within the existing L_X -sigma_v relation.Comment: MNRAS, in pres
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
The Luminosity Function of 81 Abell Clusters from the CRoNaRio catalogues
We present the composite luminosity function (hereafter LF) of galaxies for
81 Abell clusters studied in our survey of the Northern Hemisphere, using DPOSS
data processed by the CRoNaRio collaboration. The derived LF is very accurate
due to the use of homogeneous data both for the clusters and the control fields
and to the local estimate of the background, which takes into account the
presence of large-scale structures and of foreground clusters and groups. The
global composite LF is quite flat down to has a slope
with minor variations from blue to red filters, and
mag ( km s Mpc) in the
and filters, respectively (errors are detailed in the text). We find a
significant difference between rich and poor clusters thus arguing in favour of
a dependence of the LF on the properties of the environment.Comment: 8 pages, 5 figures. Contribution to the IAP 2000 Conference
"Constructing the Universe with Clusters of Galaxies", Paris, July 200
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
Rapid and MR-Independent IK1 activation by aldosterone during ischemia-reperfusion
In ST elevation myocardial infarction (STEMI) context, clinical studies have shown the deleterious
effect of high aldosterone levels on ventricular arrhythmia occurrence and cardiac
mortality. Previous in vitro reports showed that during ischemia-reperfusion, aldosterone
modulates K+ currents involved in the holding of the resting membrane potential (RMP).
The aim of this study was to assess the electrophysiological impact of aldosterone on IK1
current during myocardial ischemia-reperfusion. We used an in vitro model of “border zone”
using right rabbit ventricle and standard microelectrode technique followed by cell-attached
recordings from freshly isolated rabbit ventricular cardiomyocytes. In microelectrode experiments,
aldosterone (10 and 100 nmol/L, n=7 respectively) increased the action potential
duration (APD) dispersion at 90% between ischemic and normoxic zones (from 95±4ms to
116±6 ms and 127±5 ms respectively, P<0.05) and reperfusion-induced sustained premature
ventricular contractions occurrence (from 2/12 to 5/7 preparations, P<0.05). Conversely,
potassium canrenoate 100 nmol/L and RU 28318 1 μmol/l alone did not affect AP
parameters and premature ventricular contractions occurrence (except Vmax which was
decreased by potassium canrenoate during simulated-ischemia). Furthermore, aldosterone
induced a RMP hyperpolarization, evoking an implication of a K+ current involved in the
holding of the RMP. Cell-attached recordings showed that aldosterone 10 nmol/L quickly
activated (within 6.2±0.4 min) a 30 pS K+-selective current, inward rectifier, with pharmacological
and biophysical properties consistent with the IK1 current (NPo =1.9±0.4 in control vs
NPo=3.0±0.4, n=10, P<0.05). These deleterious effects persisted in presence of RU 28318,
a specific MR antagonist, and were successfully prevented by potassium canrenoate, a non
specific MR antagonist, in both microelectrode and patch-clamp recordings, thus indicating
a MR-independent IK1 activation. In this ischemia-reperfusion context, aldosterone induced
rapid and MR-independent deleterious effects including an arrhythmia substrate (increased
APD90 dispersion) and triggered activities (increased premature ventricular contractions
occurrence on reperfusion) possibly related to direct IK1 activation
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
“Bit Standard”- Bitcoin between reality and risks of a “halfway-money”
This work provides an explanation of the market underlying the evolution due to modern technologies and technical advances, especially in transactions. In this regard, the authors specify the aspect related to the creation of virtual currencies like bitcoin that can circulate thanks to the Blockchain system through miners\u2019 work. The authors consider areas related to the warnings on the use and exchange of virtual currencies. The aim is to conceptualize in a graphical way the current operational transaction in bitcoin through the existing exchange platforms. The authors try to attest the fickleness of the disintermediation ideal founding Bitcoin. The analysis purposed could be interesting and useful to provide a kind of interpretation of the phenomenon and a general overview about Bitcoin system
The Determination of Nuclear Level Densities from Experimental Information -
A novel Information Theory based method for determining the density of states
from prior information is presented. The energy dependence of the density of
states is determined from the observed number of states per energy interval and
model calculations suggest that the method is sufficiently reliable to
calculate the thermal properties of nuclei over a reasonable temperature range.Comment: 7 pages + 6 eps figures, REVTEX 3.
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