3,217 research outputs found
A New Empirical Model for the Structural Analysis of Early-type Galaxies and a Critical Review of the Nuker Model
The Nuker law was designed to match the inner few (~3-10) arcseconds of
predominantly nearby (< 30 Mpc) early-type galaxy light-profiles; it was never
intended to describe an entire profile. The Sersic model, on the other hand,
was developed to fit the entire profile; however, due to the presence of
partially depleted galaxy cores, the Sersic model cannot always describe the
very inner region. We have therefore developed a new empirical model consisting
of an inner power-law, a transition region, and an outer Sersic model to
connect the inner and outer structure of elliptical galaxies. Moreover, the
stability of the Nuker model parameters are investigated. Surprisingly, none
are found to be stable quantities; all are shown to vary systematically with a
profile's fitted radial extent, and often by more than 100%. Considering
elliptical galaxies spanning a range of 7.5 magnitudes, the central stellar
density of the underlying host galaxy is observed to increase with galaxy
luminosity until the onset of core formation, detected only in the brightest
elliptical galaxies. We suggest that the so-called ``power-law'' galaxies may
actually be described by the Sersic model over their entire radial range
Scaling relations of cluster elliptical galaxies at z~1.3. Distinguishing luminosity and structural evolution
[Abridged] We studied the size-surface brightness and the size-mass relations
of a sample of 16 cluster elliptical galaxies in the mass range
10^{10}-2x10^{11} M_sun which were morphologically selected in the cluster RDCS
J0848+4453 at z=1.27. Our aim is to assess whether they have completed their
mass growth at their redshift or significant mass and/or size growth can or
must take place until z=0 in order to understand whether elliptical galaxies of
clusters follow the observed size evolution of passive galaxies. To compare our
data with the local universe we considered the Kormendy relation derived from
the early-type galaxies of a local Coma Cluster reference sample and the WINGS
survey sample. The comparison with the local Kormendy relation shows that the
luminosity evolution due to the aging of the stellar content already assembled
at z=1.27 brings them on the local relation. Moreover, this stellar content
places them on the size-mass relation of the local cluster ellipticals. These
results imply that for a given mass, the stellar mass at z~1.3 is distributed
within these ellipticals according to the same stellar mass profile of local
ellipticals. We find that a pure size evolution, even mild, is ruled out for
our galaxies since it would lead them away from both the Kormendy and the
size-mass relation. If an evolution of the effective radius takes place, this
must be compensated by an increase in the luminosity, hence of the stellar mass
of the galaxies, to keep them on the local relations. We show that to follow
the Kormendy relation, the stellar mass must increase as the effective radius.
However, this mass growth is not sufficient to keep the galaxies on the
size-mass relation for the same variation in effective radius. Thus, if we want
to preserve the Kormendy relation, we fail to satisfy the size-mass relation
and vice versa.Comment: Accepted for publication in A&A, updated to match final journal
versio
Adaptive Optics Rest-Frame V-band Imaging of Lyman Break Galaxies at z~3: High-surface Density Disk-like Galaxies ?
In order to reveal the rest-frame V-band morphology of galaxies at z~3, we
conducted AO-assisted K-band imaging observations of z~3 LBGs with Mv*-0.5 to
Mv*+3.0 mag. LBGs brighter than Mv* have larger rHL (0.40") than the fainter
LBGs (0.23") on average, and there is no bright LBGs with a small rHL. The LBGs
brighter than Mv* have red rest-frame U-V colors (average of 0.2 mag) and most
of the fainter LBGs show blue rest-frame U-V colors (average of -0.4 mag). The
K-band peaks of some of the LBGs brighter than K=22.0 mag show significant
shift from those in the optical images. The images of all but one of the LBGs
with K<21.5 mag are fitted well with Sersic profile with n index less than 2,
similar to disk galaxies in the local universe. Assuming that the LBGs have a
disk-shape, we compared their size-luminosity and size-stellar mass relation
with those of z=0 and z=1 disk galaxies. The LBGs are brighter than z=0 and z=1
disk galaxies at the same effective radius. The rest-frame V-band surface
brightness of the LBGs are 2.2-2.9 mag and 1.2-1.9 mag brighter than the disk
galaxies at z=0 and z=1, respectively. The size-stellar mass relation of the
LBGs shows that the effective radii of the LBGs do not depend on their stellar
mass. For the LBGs brighter than Mv*, the average surface stellar mass density
is 3-6 times larger than those of the z=0 and z=1 disk galaxies. We also
examine the profiles of the serendipitously observed DRGs. They are also fitted
with the Sersic profiles with n<2. The implications of the dominance of n<2
population among galaxies at z~3 and the presence of the high surface stellar
mass density disk systems are discussed.Comment: Accepted for publication in Astrophysical Journal Supplement. 38
pages, 26 postscript figures. Original version with high resolution figures
is available from http://www.naoj.org/staff/akiyama/papers/LBG_AO.pd
Triple positive breast cancer. A distinct subtype?
Breast cancer is a heterogeneous disease, and within the HER-2 positive subtype this is highly exemplified by the presence of substantial phenotypical and clinical heterogeneity, mostly related to hormonal receptor (HR) expression. It is well known how HER-2 positivity is commonly associated with a more aggressive tumor phenotype and decreased overall survival and, moreover, with a reduced benefit from endocrine treatment. Preclinical studies corroborate the role played by functional crosstalks between HER-2 and estrogen receptor (ER) signaling in endocrine resistance and, more recently, the activation of ER signaling is emerging as a possible mechanism of resistance to HER-2 blocking agents. Indeed, HER-2 positive breast cancer heterogeneity has been suggested to underlie the variability of response not only to endocrine treatments, but also to HER-2 blocking agents. Among HER-2 positive tumors, HR status probably defines two distinct subtypes, with dissimilar clinical behavior and different sensitivity to anticancer agents. The triple positive subtype, namely, ER/PgR/Her-2 positive tumors, could be considered the subset which most closely resembles the HER-2 negative/HR positive tumors, with substantial differences in biology and clinical outcome. We argue on whether in this subgroup the "standard" treatment may be considered, in selected cases, i.e., small tumors, low tumor burden, high expression of both hormonal receptors, an overtreatment. This article review the existing literature on biologic and clinical data concerning the HER-2/ER/PgR positive tumors, in an attempt to better define the HER-2 subtypes and to optimize the use of HER-2 targeted agents, chemotherapy and endocrine treatments in the various subsets
Intra-varietal variability of Romanesco variety (Vitis vinifera L.)
Most historical sources that describe the presence of Romanesco variety in vine-growing
areas of Lazio Region (Italy) highlighted the variability of morphological traits within the variety.
This partly justifies the presence of different synonyms, true or presumed, reported by many authors
for this grape variety. With the aim of analysing this variability, eight accessions related to the
variety, collected in Lazio Region and grown in the DAFNE grape germplasm collection, have been
characterized over five productive seasons. The ampelographic description was carried out using 50
OIV morphological descriptors and ampelometric analyses were carried out on mature leaves by
SuperAmpelo software. The DNA of the different accessions, extracted from young leaves, was
analyzed using 14 microsatellite loci. Furthermore, at harvest, the grapes of each accession were
sampled to assess main compositive characteristics. Results showed differences among accessions
on some ampelographic descriptors of the mature leaf, of the bunch, and on phenological stages.
Microsatellite profiles allowed for classification of the accessions into three distinct groups.
Qualitative analysis of the berry skin showed differences among accessions in the content of the
main classes of phenolic compounds
The interplay of intrinsic and extrinsic bounded noises in genetic networks
After being considered as a nuisance to be filtered out, it became recently
clear that biochemical noise plays a complex role, often fully functional, for
a genetic network. The influence of intrinsic and extrinsic noises on genetic
networks has intensively been investigated in last ten years, though
contributions on the co-presence of both are sparse. Extrinsic noise is usually
modeled as an unbounded white or colored gaussian stochastic process, even
though realistic stochastic perturbations are clearly bounded. In this paper we
consider Gillespie-like stochastic models of nonlinear networks, i.e. the
intrinsic noise, where the model jump rates are affected by colored bounded
extrinsic noises synthesized by a suitable biochemical state-dependent Langevin
system. These systems are described by a master equation, and a simulation
algorithm to analyze them is derived. This new modeling paradigm should enlarge
the class of systems amenable at modeling.
We investigated the influence of both amplitude and autocorrelation time of a
extrinsic Sine-Wiener noise on: the Michaelis-Menten approximation of
noisy enzymatic reactions, which we show to be applicable also in co-presence
of both intrinsic and extrinsic noise, a model of enzymatic futile cycle
and a genetic toggle switch. In and we show that the
presence of a bounded extrinsic noise induces qualitative modifications in the
probability densities of the involved chemicals, where new modes emerge, thus
suggesting the possibile functional role of bounded noises
Discovery of a new M32-like "Compact Elliptical" galaxy in the halo of the Abell 496 cD galaxy
Aims: ``Compact ellipticals'' are so rare that a search for M32 analogs is
needed to ensure the very existence of this class. Methods: We report here the
discovery of A496cE, a M32 twin in the cluster Abell 496, located in the halo
of the central cD. Results: Based on CFHT and HST imaging we show that the
light profile of A496cE requires a two component fit: a Sersic bulge and an
exponential disc. The spectrum of A496cE obtained with the ESO-VLT
FLAMES/Giraffe spectrograph can be fit by a stellar synthesis spectrum
dominated by old stars, with high values of [Mg/Fe] and velocity dispersion.
Conclusions: The capture of A496cE by the cD galaxy and tidal stripping of most
of its disc are briefly discussed.Comment: 4 pages, 4 figures, accepted for publication in A&A Letter
Identification of immunogenic candidate for new serological tests for Brucella melitensis by a proteomic approach.
Background:
The diagnosis of brucellosis by serological tests is based on antigen suspensions derived from smooth lipopolysaccharide extracts, which can give false-positive results linked to cross-reactivity with other Gram-negative microorganisms, especially Yersinia enterocolitica O:9 and Escherichia coli O157:H7.
Objective:
The objective of the present study was the characterization by proteomic analysis of specific immunogenic proteins not associated with smooth lipopolysaccharide to improve the diagnostic tests used in the ovine brucellosis eradication programs.
Methods:
The serum from a sheep positive to Brucella melitensis was treated to eliminate all antibodies against such lipopolysaccharides and highlight the reaction towards the immunoreactive proteins in western blotting.
Results:
The immunoreactive bands were identified by nLC-MS/MS, and through bioinformatics tools, it was possible to select 12 potential candidates as protein antigens specific for Brucella melitensis.
Conclusion:
The detection of new antigens not subjected to cross-reactivity with other Gram-negative microorganisms can offer additional tools for the serological diagnosis of such diseases
Drug management of atrial fibrillation in light of guidelines and current evidence: an Italian Survey on behalf of Italian Association of Arrhythmology and Cardiac Pacing
AimAtrial fibrillation is a multifaceted disease requiring personalized treatment, in accordance with current ESC guidelines. Despite a wide range of literature, we still have various aspects dividing the opinion of the experts in rate control, rhythm control and thromboembolic prophylaxis. The aim of this survey was to provide a country-wide picture of current practice regarding atrial fibrillation pharmacological management according to a patient's characteristics.MethodsData were collected using an in-person survey that was administered to members of the Italian Association of Arrhythmology and Cardiac Pacing.ResultsWe collected data from 106 physicians, working in 72 Italian hospitals from 15 of 21 regions. Our work evidenced a high inhomogeneity in atrial fibrillation management regarding rhythm control, rate control and thromboembolic prophylaxis in both acute and chronic patients. This element was more pronounced in settings in which literature shows a lack of evidence and, consequently, the indications provided by the guidelines are weak or absent.ConclusionThis National survey evidenced a high inhomogeneity in current approaches adopted for atrial fibrillation management by a sample of Italian cardiologist experts in arrhythmia management. Further studies are needed to explore if these divergences are associated with different long-term outcomes
Choosing the optimal gated window for defining target volume in lung stereotactic ablative radiotherapy
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