409 research outputs found
A comprehensive study of reported high metallicity giant HII regions. I. Detailed abundance analysis
We present long-slit observations in the optical and near infrared of
fourteen HII regions in the spiral galaxies: NGC 628, NGC 925, NGC 1232 and NGC
1637, all of them reported to have solar or oversolar abundances according to
empirical calibrations. For seven of the observed regions, ion-weighted
temperatures from optical forbidden auroral to nebular line ratios have been
obtained and for six of them, the oxygen abundances derived by standard methods
turn out to be significantly lower than solar. The other one, named CDT1 in NGC
1232, shows an oxygen abundance of 12+log(O/H) = 8.95+-0.20 and constitutes, to
the best of our knowledge, the first high metallicity HII region for which
accurate line temperatures, and hence elemental abundances, have been derived.
For the rest of the regions no line temperature measurements could be made
and the metallicity has been determined by means of both detailed
photoionisation modelling and the sulphur abundance parameter S_23. Only one of
these regions shows values of O_23 and S_23 implying a solar or oversolar
metallicity.
According to our analysis, only two of the observed regions can therefore be
considered as of high metallicity. The two of them fit the trends previously
found in other high metallicity HII regions, i.e. N/O and S/O abundance ratios
seem to be higher and lower than solar respectively.Comment: Accepted for publication by MNRA
Short-Term Energy Demand Forecast in Hotels Using Hybrid Intelligent Modeling
This paper is the extension of the conference paper: Casteleiro-Roca, J.-L.; Gómez-González, J.F.;
Calvo-Rolle, J.L.; Jove, E.; Quintián, H.; Acosta Martín, J.F.; Gonzalez Perez, S.; Gonzalez Diaz, B.;
Calero-Garcia, F. and Méndez-Perez, J.A. Prediction of the Energy Demand of a Hotel Using an Artificial
Intelligence-Based Model. In Proceedings of the 13th International Conference, Hybrid Artificial Intelligent
Systems (HAIS), Oviedo, Spain, 20–22 June 2018.[Abstract] The hotel industry is an important energy consumer that needs efficient energy management
methods to guarantee its performance and sustainability. The new role of hotels as prosumers
increases the difficulty in the design of these methods. Also, the scenery is more complex as renewable
energy systems are present in the hotel energy mix. The performance of energy management systems
greatly depends on the use of reliable predictions for energy load. This paper presents a new
methodology to predict energy load in a hotel based on intelligent techniques. The model proposed
is based on a hybrid intelligent topology implemented with a combination of clustering techniques
and intelligent regression methods (Artificial Neural Network and Support Vector Regression).
The model includes its own energy demand information, occupancy rate, and temperature as inputs.
The validation was done using real hotel data and compared with time-series models. Forecasts
obtained were satisfactory, showing a promising potential for its use in energy management systems
in hotel resortsFundación CajaCanarias; grant number PR70575
CARACTERIZACIÓN DE LA COMUNICACIÓN ORGANIZACIONAL EN LAS MEDIANAS EMPRESAS DE LA CIUDAD DE SOGAMOSO EN BOYACÁ, COLOMBIA
En la actualidad, para la gran mayoría de empresas de la ciudad de Sogamoso, la comunicación organizacional viene siendo un factor incidente en el desempeño empresarial, pero además de buscar la transmisión de información, debe también ser una clave del éxito en la gerencia moderna. Para lo cual, el presente artículo presenta los resultados más relevantes de la investigación hecha a 27 empresas de diferentes sectores empresariales de la ciudad de Sogamoso en Colombia, donde se caracterizaron los aspectos fundamentales de la comunicación organizacional; para el diseño metodológico se utilizó el tipo descriptivo y explicativo, utilizando una encuesta estructurada que se aplicó a los gerentes de dichas organizaciones encontrándose los elementos y medios de comunicación organizacional más utilizados en estos sectores empresariales
Precision abundance analysis of bright HII galaxies
We present high signal-to-noise spectrophotometric observations of seven
luminous HII galaxies. The observations have been made with the use of a
double-arm spectrograph which provides spectra with a wide wavelength coverage,
from 3400 to 10400\AA free of second order effects, of exactly the same region
of a given galaxy. These observations are analysed applying a methodology
designed to obtain accurate elemental abundances of oxygen, sulphur, nitrogen,
neon, argon and iron in the ionized gas. Four electron temperatures and one
electron density are derived from the observed forbidden line ratios using the
five-level atom approximation. For our best objects errors of 1% in
t_e([OIII]), 3% in t_e([OII]) and 5% in t_e([SIII]) are achieved with a
resulting accuracy of 7% in total oxygen abundances, O/H.
The ionisation structure of the nebulae can be mapped by the theoretical
oxygen and sulphur ionic ratios, on the one side, and the corresponding
observed emission line ratios, on the other -- the \eta and \eta' plots --. The
combination of both is shown to provide a means to test photo-ionisation model
sequences currently applied to derive elemental abundances in HII galaxies.Comment: 24 pages, 8 figures, accepted by MNRA
Mid-IR Luminosities and UV/Optical Star Formation Rates at z<1.4
UV continuum and mid-IR emission constitute two widely used star formation
indicators at intermediate and high redshifts. We study 2430 galaxies with
z<1.4 in the Extended Groth Strip with MIPS 24 mic observations from FIDEL,
spectroscopy from DEEP2, and UV, optical, and near-IR photometry from AEGIS.
The data are coupled with stellar population models and Bayesian SED fitting to
estimate dust-corrected SFRs. In order to probe the dust heating from stellar
populations of various ages, the derived SFRs were averaged over various
timescales--from 100 Myr for "current" SFR to 1--3 Gyr for long-timescale SFRs.
These SED-based UV/optical SFRs are compared to total infrared luminosities
extrapolated from 24 mic observations. We find that for the blue, actively star
forming galaxies the correlation between the IR luminosity and the UV/optical
SFR shows a decrease in scatter when going from shorter to longer SFR-averaging
timescales. We interpret this as the greater role of intermediate age stellar
populations in heating the dust than what is typically assumed. This holds over
the entire redshift range. Many so-called green valley galaxies are simply
dust-obscured actively star-forming galaxies. However, there exist 24
mic-detected galaxies, some with L>10^11 L_sun, yet with little current star
formation. For them a reasonable amount of dust absorption of stellar light is
sufficient to produce the observed levels of IR. In our sample optical and
X-ray AGNs do not contribute on average more than ~50% to the mid-IR
luminosity, and we see no evidence for a large population of "IR excess"
galaxies (Abridged).Comment: Accepted for publication in ApJ. Content identical to arXiv version
1. No color figure
Exploiting the therapeutic potential of ready-to-use drugs: Repurposing antibiotics against amyloid aggregation in neurodegenerative diseases
Neurodegenerative diseases are chronic and progressive disorders that affect specific regions of the brain, causing gradual disability and suffering that results in a complete inability of patients to perform daily functions. Amyloid aggregation of specific proteins is the most common biological event that is responsible for neuronal death and neurodegeneration in various neurodegenerative diseases. Therapeutic agents capable of interfering with the abnormal aggregation are required, but traditional drug discovery has fallen short. The exploration of new uses for approved drugs provides a useful alternative to fill the gap between the increasing incidence of neurodegenerative diseases and the long-term assessment of classical drug discovery technologies. Drug re-profiling is currently the quickest possible transition from bench to bedside. In this way, experimental evidence shows that some antibiotic compounds exert neuroprotective action through anti-aggregating activity on disease-associated proteins. The finding that many antibiotics can cross the blood-brain barrier and have been used for several decades without serious toxic effects makes them excellent candidates for therapeutic switching towards neurological disorders. The present review is, to our knowledge, the first extensive evaluation and analysis of the anti-amyloidogenic effect of different antibiotics on well-known disease-associated proteins. In addition, we propose a common structural signature derived from the antiaggregant antibiotic molecules that could be relevant to rational drug discovery.Fil: Socias, Sergio Benjamin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: González Lizarraga, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Avila, Cesar Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Vera Ocampo, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Acuña, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; Argentina. Centre National de la Recherche Scientifique; Francia. Universite de la Sorbona Nouvelle; FranciaFil: Sepúlveda Díaz, Julia E.. Universite de la Sorbona Nouvelle; Francia. Centre National de la Recherche Scientifique; FranciaFil: del Bel Belluz Guimaraes, Elaine. Universidade de Sao Paulo; BrasilFil: Raisman Vozari, Rita. Universite de la Sorbona Nouvelle; Francia. Centre National de la Recherche Scientifique; FranciaFil: Chehin, Rosana Nieves. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; Argentin
High resolution spectroscopy of the BCD galaxy Haro 15: II. Chemodynamics
We present a detailed study of the physical properties of the nebular
material in four star-forming knots of the blue compact dwarf galaxy Haro 15.
Using long-slit and echelle spectroscopy obtained at Las Campanas Observatory,
we study the physical conditions (electron density and temperatures), ionic and
total chemical abundances of several atoms, reddening and ionization structure,
for the global flux and for the different kinematical components. The latter
was derived by comparing the oxygen and sulphur ionic ratios to their
corresponding observed emission line ratios (the and ' plots) in
different regions of the galaxy. Applying the direct method or empirical
relationships for abundance determination, we perform a comparative analysis
between these regions. The similarities found in the ionization structure of
the different kinematical components implies that the effective temperatures of
the ionizing radiation fields are very similar in spite of some small
differences in the ionization state of the different elements. Therefore the
different gaseous kinematical components identified in each star forming knot
are probably ionized by the same star cluster. However, the difference in the
ionizing structure of the two knots with knot A showing a lower effective
temperature than knot B, suggests a different evolutionary stage for them
consistent with the presence of an older and more evolved stellar population in
the first.Comment: 21 pages, 6 figures, 8 tables, accepted by MNRA
Fluorescent excitation of Balmer lines in gaseous nebulae: case D
(abridged) Non-ionizing stellar continua are a source of photons for
continuum pumping in the hydrogen Lyman transitions. In the environments where
these transitions are optically thick, deexcitation occurs through higher
series lines, so that the flux in these lines has a fluorescent contribution in
addition to recombination; in particular, Balmer emissivities are
systematically enhanced above case B. The effectiveness of such mechanism in
HII regions and the adequacy of photoionization models as a tool to study it
are the two main focuses of this work. We find that photoionization models of H
II regions illuminated by low-resolution population synthesis models
significantly overpredict the fluorescent contribution to the Balmer lines.
Conversely, photoionization models in which the non-ionizing part of the
continuum is omitted or is not transferred underpredict the fluorescent
contribution to the Balmer lines, producing a bias of similar amplitude in the
opposite direction. In this paper, we carry out realistic estimations of the
fluorescent Balmer intensity and discuss the variations to be expected as the
simulated observational setup and the stellar population's parameters are
varied. In all the cases explored, we find that fluorescent excitation provides
a significant contribution. We also show that differential fluorescent
enhancement may produce line-of-sight differences in the Balmer decrement,
mimicking interstellar extinction. Fluorescent excitation emerges from our
study as a small but important mechanism for the enhancement of Balmer lines,
which should be taken into account in the abundance analysis of photoionized
regions, particularly in the case of high-precision applications such as the
determination of primordial helium.Comment: 49 pages, 14 figures. AAS Latex. Accepted for publication in the
Astrophysical Journa
A characterization of ASAS-SN core-collapse supernova environments with VLT+MUSE: I. Sample selection, analysis of local environments, and correlations with light curve properties
The analysis of core-collapse supernova (CCSN) environments can provide
important information on the life cycle of massive stars and constrain the
progenitor properties of these powerful explosions. The MUSE instrument at the
VLT enables detailed local environment constraints of the progenitors of large
samples of CCSNe. Using a homogeneous SN sample from the ASAS-SN survey has
enabled us to perform a minimally biased statistical analysis of CCSN
environments. We analyze 111 galaxies observed by MUSE that hosted 112 CCSNe
detected or discovered by the ASAS-SN survey between 2014 and 2018. The
majority of the galaxies were observed by the the AMUSING survey. Here we
analyze the immediate environment around the SN locations and compare the
properties between the different CCSN types and their light curves. We used
stellar population synthesis and spectral fitting techniques to derive physical
parameters for all HII regions detected within each galaxy, including the star
formation rate (SFR), H equivalent width (EW), oxygen abundance, and
extinction. We found that stripped-envelope (SE) SNe occur in environments with
a higher median SFR, H EW, and oxygen abundances than SNe II and SNe
IIn/Ibn. The distributions of SNe II and IIn are very similar, indicating that
these events explode in similar environments. For the SESNe, SNe Ic have higher
median SFRs, H EWs, and oxygen abundances than SNe Ib. SNe IIb have
environments with similar SFRs and H EWs to SNe Ib, and similar oxygen
abundances to SNe Ic. We also show that the postmaximum decline rate, , of
SNe II correlates with the H EW, and that the luminosity and the
parameter of SESNe correlate with the oxygen abundance,
H EW, and SFR at their environments. This suggests a connection between
the explosion mechanisms of these events to their environment properties
Abundance determination of multiple star-forming regions in the HII galaxy SDSS J165712.75+321141.4
We analyze high signal-to-noise spectrophotometric observations acquired
simultaneously with TWIN, a double-arm spectrograph, from 3400 to 10400 \AA of
three star-forming regions in the HII galaxy SDSS J165712.75+321141.4. We have
measured four line temperatures: Te([OIII]), Te([SIII]), Te([OII]), and
Te([SII]), with high precision, rms errors of order 2%, 5%, 6% and 6%,
respectively, for the brightest region, and slightly worse for the other two.
The temperature measurements allowed the direct derivation of ionic abundances
of oxygen, sulphur, nitrogen, neon and argon.
We have computed CLOUDY tailor-made models which reproduce the O2+ measured
thermal and ionic structures within the errors in the three knots, with
deviations of only 0.1 dex in the case of O+ and S2+ ionic abundances. In the
case of the electron temperature and the ionic abundances of S+/H+, we find
major discrepancies which could be consequence of the presence of colder
diffuse gas. The star formation history derived using STARLIGHT shows a similar
age distribution of the ionizing population among the three star-forming
regions. This fact suggests a similar evolutionary history which is probably
related to a process of interaction with a companion galaxy that triggered the
star formation in the different regions almost at the same time. The hardness
of the radiation field mapped through the use of the softness parameter
is the same within the observational errors for all three regions, implying
that the equivalent effective temperature of the radiation fields are very
similar for all the studied regions of the galaxy, in spite of some small
differences in the ionization state of different elements.Comment: 18 pages, 10 figures, accepted by MNRA
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