407 research outputs found
Detailed AGB evolutionary models and near infrared colours of intermediate-age stellar populations: Tests on star clusters
We investigate the influence of Asymptotic Giant Branch stars on integrated
colours of star clusters of ages between ~100 Myr and a few gigayears, and
composition typical for the Magellanic Clouds. We use state-of-the-art stellar
evolution models that cover the full thermal pulse phase, and take into account
the influence of dusty envelopes on the emerging spectra. We present an
alternative approach to the usual isochrone method, and compute integrated
fluxes and colours using a Monte Carlo technique that enables us to take into
account statistical fluctuations due to the typical small number of cluster
stars. We demonstrate how the statistical variations in the number of
Asymptotic Giant Branch stars and the temperature and luminosity variations
during thermal pulses fundamentally limit the accuracy of the comparison (and
calibration, for population synthesis models that require a calibration of the
Asymptotic Giant Branch contribution to the total luminosity) with star cluster
integrated photometries. When compared to observed integrated colours of
individual and stacked clusters in the Magellanic Clouds, our predictions match
well most of the observations, when statistical fluctuations are taken into
account, although there are discrepancies in narrow age ranges with some (but
not all) set of observations.Comment: 12 pages, 14 figures, accepted for publication in A&
The Role of Dust in Models of Population Synthesis
We have employed state-of-the-art evolutionary models of low and
intermediate-mass AGB stars, and included the effect of circumstellar dust
shells on the spectral energy distribution (SED) of AGB stars, to revise the
Padua library of isochrones (Bertelli et al. 1994). The major revision involves
the thermally pulsing AGB phase, that is now taken from fully evolutionary
calculations by Weiss & Ferguson (2009). Two libraries of about 600 AGB
dust-enshrouded SEDs each have also been calculated, one for oxygen-rich
M-stars and one for carbon-rich C-stars. Each library accounts for different
values of input parameters like the optical depth {\tau}, dust composition, and
temperature of the inner boundary of the dust shell. These libraries of dusty
AGB spectra have been implemented into a large composite library of theoretical
stellar spectra, to cover all regions of the Hertzsprung-Russell Diagram (HRD)
crossed by the isochrones. With the aid of the above isochrones and libraries
of stellar SEDs, we have calculated the spectro-photometric properties (SEDs,
magnitudes, and colours) of single-generation stellar populations (SSPs) for
six metallicities, more than fifty ages (from 3 Myr to 15 Gyr), and nine
choices of the Initial Mass Function. The new isochrones and SSPs have been
compared to the colour-magnitude diagrams (CMDs) of field populations in the
LMC and SMC, with particular emphasis on AGB stars, and the integrated colours
of star clusters in the same galaxies, using data from the SAGE (Surveying the
Agents of Galaxy Evolution) catalogues. We have also examined the integrated
colours of a small sample of star clusters located in the outskirts of M31. The
agreement between theory and observations is generally good. In particular, the
new SSPs reproduce the red tails of the AGB star distribution in the CMDs of
field stars in the Magellanic Clouds.Comment: Accepted for publication in MNRA
Corrigendum to “A generalization of Iseki\u27s formula”
This corrigendum is written to correct an error in Theorem 1 in [1]
QoL in Southtyrol T1D Pediatric Patients Psycho-social Well-being, Quality of Life, Health Status and Family Conflicts in a South-tyrolean Group of Pediatric Patients with Diabetes Mellitus Type I
Background:Psychological well-being and metabolic control in pediatric patients with diabetes mellitus type I (T1D) could be negatively influenced by adolescence current age, age at the diagnosis, lower economic condition and lower education status and by higher family conflict. However, they reported lower or comparable levels of emotional difficulties compared with normative population.Objective:To understand psycho-social symptoms, quality of life, health status and family conflicts of pediatric patients with T1D in the unique cultural environment of South-Tyrol. The present study has two goals. The first is to understand psychological symptoms and to investigatethe possible risk factors. The second deals with the subgroup of adolescents, comparing their psychological functioning with a healthy control group.Methods:Patients (n=59) with a mean age of 13.19 years (SD=3.26; range 8\u201318) were contacted at the Day Hospital check-ups and self-and proxy-reported questionnaires were administered: CBCL/ YSR, DFCS-R, DQOLY-SF. From this group, 45 patients aged 11\u201318 were matched by gender and age in months with a control group of healthy peers. Results:Glycemic control was severely inadequate and a subgroup of patients showed lower indexes of total competencies and activities performed, especially if they were of poor economic condition and had the illness for a longer duration. The adolescent patients self-reported better psychological functioning than their healthy peers, except for conduct problems. Conclusions:Specific psycho-social interventions should address the dangerous levels of metabolic control indexes and mitigate the patients\u2019 conduct problems
The Opacity of Spiral Galaxy Disks VIII: Structure of the Cold ISM
The quantity of dust in a spiral disk can be estimated using the dust's
typical emission or the extinction of a known source. In this paper, we compare
two techniques, one based on emission and one on absorption, applied on
sections of fourteen disk galaxies. The two measurements reflect, respectively
the average and apparent optical depth of a disk section. Hence, they depend
differently on the average number and optical depth of ISM structures in the
disk. The small scale geometry of the cold ISM is critical for accurate models
of the overall energy budget of spiral disks. ISM geometry, relative
contributions of different stellar populations and dust emissivity are all free
parameters in galaxy Spectral Energy Distribution (SED) models; they are also
sometimes degenerate, depending on wavelength coverage. Our aim is to constrain
typical ISM geometry. The apparent optical depth measurement comes from the
number of distant galaxies seen in HST images through the foreground disk. We
measure the IR flux in images from the {\it Spitzer} Infrared Nearby Galaxy
Survey in the same section of the disk that was covered by HST. A physical
model of the dust is fit to the SED to estimate the dust surface density, mean
temperature, and brightness in these disk sections. The surface density is
subsequently converted into the average optical depth estimate. The two
measurements generally agree. The ratios between the measured average and
apparent optical depths of the disk sections imply optically thin clouds in
these disks. Optically thick disks, are likely to have more than a single cloud
along the line-of-sight.Comment: 31 pages, 5 figures, 4 tables, accepted for publication in A
GALEX UV properties of the polar ring galaxy MCG-05-07-001 and the shell galaxies NGC 1210 and NGC 5329
Systems of shells and polar rings in early-type galaxies are considered "bona
fide" tracers of mass accretion and/or mergers. Their high frequency in low
density environments suggests that such episodes could drive the evolution of
at least a fraction of the early-type galaxy population. Their UV emission is
crucial to test whether these galaxies host ongoing/recent star formation. We
used far and near ultraviolet, optical, near infrared images, HI maps, and line
strength indices to investigate the nuclear and outer regions of the galaxies
as well as the regions where fine structures are present. The GALEX Near (NUV)
and Far UV (FUV) images of MCG-05-07-001 and NGC 1210 show complex tidal tails
and debris structures. The UV morphology of both galaxies appears so different
from the optical one that the early-type classification may not apply. In both
GALEX bands the polar ring of MCG-05-07-001 is the dominant feature, whereas an
extended tidal tail dominates the FUV bands of NGC 1210. In MCG-05-07-001 and
NGC 1210 there is a strong correlation between structures detected in the FUV
and NUV bands and in HI. NGC 5329 does not show evidence of shells in the UV.
We try to constrain the age of the accretion episode or merger which gave rise
to the shells and polar rings with the aid of composite stellar populations
that take the presence of dust into account. The presence of HI in both
MCG-05-07-001 and NGC 1210 argues in favour of wet mergers. Models suggest the
presence of very young stellar populations in MCG-05-07-001: the observations
could be explained in the framework of a conspicuous burst of star formation
that occurred <=1 Gyr ago and involved a large fraction of the galaxy mass. Our
models suggest that also the nuclei of NGC 1210 and NGC 5329 could have been
rejuvenated by an accretion episode about 2-4 Gyr ago. (abridged)Comment: 35 pages, 15 figures, accepted for publication in Astronomy and
Astrophysic
Pleiotropic antitumor effects of the pan-HDAC inhibitor ITF2357 against c-Myc-overexpressing human B-cell non-Hodgkin lymphomas,
Histone deacetylases (HDAC) extensively contribute to the c-Myc oncogenic program, pointing to their inhibition as an effective strategy against c-Myc-overexpressing cancers. We, thus, studied the therapeutic activity of the new-generation pan-HDAC inhibitor ITF2357 (Givinostat®) against c-Myc-overexpressing human B-cell non-Hodgkin lymphomas (B-NHLs). ITF2357 anti-proliferative and pro-apoptotic effects were analyzed in B-NHL cell lines with c-Myc translocations (Namalwa, Raji and DOHH-2), stabilizing mutations (Raji) or post-transcriptional alterations (SU-DHL-4) in relationship to c-Myc modulation. ITF2357 significantly delayed the in vitro growth of all B-NHL cell lines by inducing G1 cell-cycle arrest, eventually followed by cell death. These events correlated with the extent of c-Myc protein, but not mRNA, downregulation, indicating the involvement of post-transcriptional mechanisms. Accordingly, c-Myc-targeting microRNAs let-7a and miR-26a were induced in all treated lymphomas and the cap-dependent translation machinery components 4E-BP1, eIF4E and eIF4G, as well as their upstream regulators, Akt and PIM kinases, were inhibited in function of the cell sensitivity to ITF2357, and, in turn, c-Myc downregulation. In vivo, ITF2357 significantly hampered the growth of Namalwa and Raji xenografts in immunodeficient mice. Noteworthy, its combination with suboptimal cyclophosphamide, achieved complete remissions in most animals and equaled or even exceeded the activity of optimal cyclophosphamide. Collectively, our findings provide the rationale for testing the clinical advantages of adding ITF2357 to current therapies for the still very ominous c-Myc-overexpressing lymphomas. They equally provide the proof-of-concept for its clinical evaluation in rational combination with the promising inhibitors of B-cell receptor and PI3K/Akt/mTOR axis currently in the process of development
Status and challenges for the concept design development of the EU DEMO Plant Electrical System
The EU DEMO Plant Electrical System (PES) main scopes are to supply all the plant electrical loads and to deliver to the Power Transmission Grid (PTG) the net electrical power generated. The studies on the PES during the Pre-Concept Design (PCD) Phase were mainly addressed to understand the possible issues, related to the special features both of the power generated, with respect to a power plant of the same size, and of the power to be supplied to the electrical loads. For this purpose, the approach was to start the design of the different PES components adopting technologies already utilized in fusion experiments and in Nuclear Power Plants (NPP) to verify their applicability and identify possible limits when scaled to the DEMO size and applied to the specific pulsed operating conditions. This work is not completed, however several issues have been already identified related to the pulsed operation of the turbine generator, the large amount of recirculation power, the very high peaks of active power required for the plasma formation and control, the huge reactive power demand, if thyristor converter technology was adopted to supply the superconducting coils, etc.. The paper gives an overview on the features and scope of the PES and its subsystems, on the main achievements during the Pre-Concept Design (PCD) Phase, on the challenges for the development of the conceptual design in the next framework program and on the plan to face them
A Tonnetz Model for pentachords
This article deals with the construction of surfaces that are suitable for
representing pentachords or 5-pitch segments that are in the same class.
It is a generalization of the well known \"Ottingen-Riemann torus for triads of
neo-Riemannian theories. Two pentachords are near if they differ by a
particular set of contextual inversions and the whole contextual group of
inversions produces a Tiling (Tessellation) by pentagons on the surfaces. A
description of the surfaces as coverings of a particular Tiling is given in the
twelve-tone enharmonic scale case.Comment: 27 pages, 12 figure
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