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

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    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

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    [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 ?

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    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?

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    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.)

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    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

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    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: (i)(i) the Michaelis-Menten approximation of noisy enzymatic reactions, which we show to be applicable also in co-presence of both intrinsic and extrinsic noise, (ii)(ii) a model of enzymatic futile cycle and (iii)(iii) a genetic toggle switch. In (ii)(ii) and (iii)(iii) 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

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    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.

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    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

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    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
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