491 research outputs found
An empirical calibration of Lick indices using Milky Way Globular Clusters
To provide an empirical calibration relation in order to convert Lick indices
into abundances for the integrated light of old, simple stellar populations for
a large range in the observed [Fe/H] and [alpha/Fe]. This calibration
supersedes the previously adopted ones because it is be based on the real
abundance pattern of the stars instead of the commonly adopted metallicity
scale derived from the colours. We carried out a long-slit spectroscopic study
of 23 Galactic globular cluster for which detailed chemical abundances in stars
have been recently measured. The line-strength indices, as coded by the Lick
system and by Serven et al. (2005), were measured in low-resolution integrated
spectra of the GC light. The results were compared to average abundances and
abundance ratios in stars taken from the compilation by Pritzl et al. (2005) as
well as to synthetic models. Fe-related indices grow linearly as a function of
[Fe/H] for [Fe/H]>-2. Mg-related indices respond in a similar way to [Mg/H]
variations, however Mgb turns out to be a less reliable metallicity indicator
for [Z/H]<-1.5 . Despite the known Mg overabundance with respect to Fe in GC
stars, it proved impossible to infer a mean [Mg/Fe] for integrated spectra that
correlates with the resolved stars properties, because the sensitivity of the
indices to [Mg/Fe] is smaller at lower metallicities. We present empirical
calibrations for Ca, TiO, Ba and Eu indices as well as the measurements of
H_alpha and NaD.Comment: 16 pages, 15 figures, to appear on A&
La recuperación del patio en la arquitectura doméstica mudéjar. Restauraciones en el Albaicín de Granada en los últimos treinta años
Once the focal point of Mudejar houses in Granada, the courtyard is one of the elements that have undergone most transformation in the process of architectural evolution.
The renewed use of these domestic structures as a result of refurbishment for new or similar purposes with respect to their original use has inspired a wide range of very different interventions on the unifying element of the courtyard.
In a study of a large sample of seventy homes which have been subject to restoration over the last thirty years in Granada, we analysed the intervention methodologies employed, the criteria defined and the construction processes of restoration and conservation.
This has yielded a historical perspective of the sample in terms of how the restoration of Mudejar courtyards has evolved in Granada, encompassing stylistic reinterpretations in the earliest stages to the contemporary criteria of authenticity and architectural reinterpretation in recent interventions.El patio, como núcleo central de la casa mudéjar granadina ha sido uno de los elementos que ha sufrido más transformaciones en los procesos de evolución arquitectónica.
La revalorización de estas arquitecturas domésticas a través de su rehabilitación para nuevos o análogos usos respecto a los originales, ha motivado intervenciones de muy diferente índole sobre el elemento centralizador del patio.
A partir del estudio de una muestra significativa de setenta viviendas intervenidas en los últimos treinta años en Granada, analizamos las metodologías de actuación, los criterios definidos y los procesos constructivos de restauración y conservación.
De este modo se obtiene una visión de conjunto diacrónica de la evolución del proceso restaurador en Granada sobre esta tipología, que abarca desde las reinterpretaciones en estilo en las etapas más tempranas a los criterios de autenticidad y de reinterpretación arquitectónica desde la contemporaneidad para las actuaciones más actuales
Risk-taking attitudes of people who seek health care: An exploratory approach through lottery games using generalized estimating equations
Background: The characterization of the risk-taking attitude of individuals may be useful for planning health care interventions. It has been attempted to study expressions of risk-taking attitude and evaluate characteristics of a standard lottery game in a population that seeks health care to elicit these attitudes. Methods: Multicentric cross-sectional study. Demographic and socioe-conomic characteristics, quality of life (EuroQol-5D), and health risk behaviors were collected from 662 users of 23 health centers selected by random sampling. Risk-taking attitude was evaluated by means of a self-evaluation scale and two lotteries games (L1 and L2; L2 included the possibility of economic losses). Generalized estimating equations (GEE) explicative models were used to evaluate the variability of risk-taking attitude. Results: Nineteen percent out of interviewed people (CI95%: 15.6-22.6%) expressed a high risk appetite, but only 10.0% (CI95% 7.0 to 13.0) were classified as risk-seeking by L2. It was found association between increased risk appetite and having a better perception of health status (0.110. CI95%: 0.007-0.212) or a higher income (0.010. CI95%: 0.017-0.123) or smoking status (0.059. CI95%: 0.004-0.114). Being Spanish was associated with lower risk appetite (-0.105. CI95%: -0.005 -0.205), as being over 65 (-0.031. CI95%:- 0.061- -0.001) or a woman (-0.038. CI95%:-0.064- -0.012). The intraclass correlation coefficient for self-evaluation scale was 0.511 (95% CI: 0.372 to 0.629), 0.571 (95% CI: 0.441-0.678) for L1 and 0.349 (95% CI: 0.186-0.493) for L2. Conclusions: People who seek health care express certain inclination to risk, but this feature is attenuated when methodologies involving losses are used. Risk appetite seems greater in young people, males, people with better health, or more income, and in immigrants. Lottery games such as the proposed ones are a simple and useful tool to estimate individuals'' inclination to risk
A case of feline gastrointestinal eosinophilic sclerosing fibroplasia associated with phycomycetes
Feline gastrointestinal eosinophilic sclerosing fibroplasia (FGESF) is a recently described inflammatory condition of domestic cats with unknown aetiology. A proportion of cases of FGESF are associated with bacteria, but antibiotic treatment is ineffective. It has been hypothesized that genetically predisposed cats may develop FGESF in response to the introduction of bacteria or other antigens into the intestinal wall. A 9- month-old male Persian cat presented with a history of marked acute haematemesis. A mass (10 cm diameter) was detected within the pylorus and proximal duodenum and this was not surgically accessible. On necropsy examination the duodenal wall was seen to be markedly thickened with extensive mucosal ulceration. Microscopically, there were haphazardly oriented trabecular bands of dense eosinophilic collagen,separated by wide, clear areas containing variable numbers of fibroblasts, eosinophils, mast cells, neutrophils,macrophages, lymphocytes and plasma cells. Numerous pleomorphic, non-parallel walled, sparsely septate hyphae, characteristic of phycomycetes, were present within the collagen matrix. Colonies of gram-positive and gram-negative rods were also present within the lesion. This is the first description of FGESF with intralesional fungi
The link between the masses and central stellar populations of S0 galaxies
Using high signal-to-noise ratio VLT/FORS2 long-slit spectroscopy, we have
studied the properties of the central stellar populations and dynamics of a
sample of S0 galaxies in the Fornax Cluster. The central absorption-line
indices in these galaxies correlate well with the central velocity dispersions
(Sigma0) in accordance with what previous studies found for elliptical
galaxies. However, contrary to what it is usually assumed for cluster
ellipticals, the observed correlations seem to be driven by systematic age and
alpha-element abundance variations, and not changes in overall metallicity. We
also found that the observed scatter in the Index-Sigma0 relations can be
partially explained by the rotationally-supported nature of these systems.
Indeed, even tighter correlations exist between the line indices and the
maximum circular velocity of the galaxies. This study suggests that the
dynamical mass is the physical property driving these correlations, and for S0
galaxies such masses have to be estimated assuming a large degree of rotational
support. The observed trends imply that the most massive S0s have the shortest
star-formation timescales and the oldest stellar populations.Comment: 21 pages, 17 figures, 9 tables, accepted for publication in MNRA
MEGASTAR - III. Stellar parameters and data products for DR1 late-type stars
© The Authors 2023. This work is part of the grants I+D+i RTI2018-096188-B-I00 and PID2019-107408GB-C41, which have been funded by Ministerio de Ciencia e Innovación and Agencia Estatal de Investigación (MCIN/AEI/10.13039/501100011033). It has been also partially funded by FRACTAL, INAOE and CIEMAT. S.R.B. thanks the financial support by MCIN/AEI/10.13039/501100011033 (contract FJC 2020-045785-I) and NextGeneration EU/PRTR and MIU (UNI/551/2021) through a Margarita Salas grant. This work is based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos, in the island of La Palma. This work is based on data obtained with MEGARA instrument, funded by European Regional Development Funds (ERDF), through Programa Operativo Canarias FEDER 2014-2020. The authors thank the support given by Dr. Antonio Cabrera and Dr. Daniel Reverte, GTC Operations Group staff, during the preparation and execution of the observations at the GTC. This research made use of Astropy (Astropy Collaboration et al. 2018), a community-developed core Python package for Astronomy. This research has made use of the SIMBAD database and the VizieR catalogue access tool, CDS, Strasbourg, France (DOI: 10.26093/cds/vizier). The original description of the VizieR service was published in A&AS 143, 23. This work has made use of data from the European Space Agency (ESA) mission Gaia (https: //www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos. esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. We are very grateful to the reviewer whose comments and suggestions have helped to improve the manuscript.MEGARA is the optical integral field and multi-object spectrograph at the Gran Telescopio Canarias. We have created MEGASTAR, an empirical library of stellar spectra obtained using MEGARA at high resolution R = 20 000 (FWHM), available in two wavelength ranges: one centered in Hα, from 6420 to 6790 Å and the other centered in the Ca ii triplet, from 8370 to 8885 Å (HR-R and HR-I VPH-grating configurations). In this work, we use MEGASTAR spectra, combination of these two short wavelength intervals, to estimate the stellar parameters namely effective temperature, surface gravity and metallicity (and their associated errors) for a sample of 351 MEGASTAR members with spectral types earlier than B2. We have applied a χ^(2) technique by comparing MEGASTAR data to theoretical stellar models. For those stars with stellar parameters derived in the literature, we have obtained a good agreement between those published parameters and ours. Besides the stellar parameters, we also provide several products like the rectified spectra, radial velocities and stellar indices for this sample of stars. In a near future, we will use MEGASTAR spectra and their derived stellar parameters to compute stellar population evolutionary synthesis models, which will contribute to a better interpretation of star clusters and galaxies spectra obtained with MEGARA.Depto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasTRUEMinisterio de Ciencia e InnovaciónAgencia Estatal de InvestigaciónFRACTALNextGeneration EU/PRTR and MIU through a Margarita Salas grantEuropean Regional Development Funds (ERDF), through Programa Operativo Canarias FEDER 2014-2020INAOECIEMATpu
A multiwavelength approach to the SFR estimation in galaxies at intermediate redshifts
We use a sample of 7 starburst galaxies at intermediate redshifts (z ~ 0.4
and z ~ 0.8) with observations ranging from the observed ultraviolet to 1.4
GHz, to compare the star formation rate (SFR) estimators which are used in the
different wavelength regimes. We find that extinction corrected Halpha
underestimates the SFR, and the degree of this underestimation increases with
the infrared luminosity of the galaxies. Galaxies with very different levels of
dust extinction as measured with SFR(IR)/SFR(Halpha, uncorrected for
extinction) present a similar attenuation A[Halpha], as if the Balmer lines
probed a different region of the galaxy than the one responsible for the bulk
of the IR luminosity for large SFRs. In addition, SFR estimates derived from
[OII]3727 match very well those inferred from Halpha after applying the
metallicity correction derived from local galaxies. SFRs estimated from the UV
luminosities show a dichotomic behavior, similar to that previously reported by
other authors in galaxies at z <~ 0.4. Here we extend this result up to z ~
0.8. Finally, one of the studied objects is a luminous compact galaxy (LCG)
that may be suffering similar dust-enshrouded star formation episodes. These
results highlight the relevance of quantifying the actual L(IR) of LCGs, as
well as that of a much larger and generic sample of luminous infrared galaxies,
which will be possible after the launch of SIRTF.Comment: Accepted for publication in The Astrophysical Journa
The stellar population histories of early-type galaxies. III. The Coma Cluster
We present stellar population parameters of twelve early-type galaxies (ETGs)
in the Coma Cluster based on spectra obtained using the Low Resolution Imaging
Spectrograph on the Keck II Telescope. Our data allow us to examine in detail
the zero-point and scatter in their stellar population properties. Our ETGs
have SSP-equivalent ages of on average 5-8 Gyr with the models used here, with
the oldest galaxies having ages of ~10 Gyr old. This average age is identical
to the mean age of field ETGs. Our ETGs span a large range in velocity
dispersion but are consistent with being drawn from a population with a single
age. Specifically, ten of the twelve ETGs are consistent within their formal
errors of having the same age, 5.2+/-0.2 Gyr, over a factor of more than 750 in
mass. We therefore find no evidence for downsizing of the stellar populations
of ETGs in the core of the Coma Cluster. We suggest that Coma Cluster ETGs may
have formed the majority of their mass at high redshifts but suffered small but
detectable star formation events at z~0.1-0.3. Previous detections of
'downsizing' from stellar populations of local ETGs may not reflect the same
downsizing seen in lookback studies of RSGs, as the young ages of the local
ETGs represent only a small fraction of their total masses. (abridged)Comment: 49 pages, 20 figures (19 EPS, 1 JPEG). MNRAS, in press. For version
with full resolution of Fig. 1 see
http://www.astro.rug.nl/~sctrager/coma.pdf; for Table 2, see
http://www.astro.rug.nl/~sctrager/coma_table2.pdf; for Table B3, see
http://www.astro.rug.nl/~sctrager/coma_tableB3.pd
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