142 research outputs found
Line temperatures and elemental abundances in HII galaxies
We present long-slit spectrophotometric observations in the red and near
infrared of 12 HII galaxies. The spectral range includes the sulphur lines
[SII] at wavelengths 6716, 6731 angstroms and [SIII] at 6312 angstroms and
9069, 9532 angstroms. For all of the observed galaxies, at least three
ion-weighted temperatures from forbidden auroral to nebular line ratios have
been obtained and the relations between the different line temperatures have
been discussed. It is found that, for some objects, the [OII] temperatures
derived from those of [OIII] through the use of photo-ionisation models,
without taking into account the effect of density, can lead to a significant
underestimate of the O+/H+ ionic abundance and hence of the total oxygen
abundance.Comment: 16 pages, 11 Postscript figures. Accepted for publication by MNRA
An empirical calibration of sulphur abundance in ionised gaseous nebulae
We have derived an empirical calibration of the abundance of S/H as a
function of the S23 parameter, defined using the bright sulphur lines of [SII]
and SIII]. Contrary to what is the case for the widely used O parameter,
the calibration remains single valued up to the abundance values observed in
the disk HII regions. The calibration is based on a large sample of nebulae for
which direct determinations of electron temperatures exist and the sulphur
chemical abundances can be directly derived. ICFs, as derived from the [SIV]
10.52 emission line (ISO observations), are shown to be well reproduced
by Barker's formula for a value of alpha = 2.5. At any rate, only about 30% of
the objects in the sample require ICFs larger than 1.2. The use of the proposed
calibration opens the possibility of performing abundance analysis with red to
IR spectroscopic data using S/H as a metallicity tracer.Comment: 9 pages, 5 figures. Accepted for publication by Astronomy &
Astrophysic
Optical and mid-infrared neon abundance determinations in star-forming regions
We employed observational spectroscopic data of star-forming regions compiled
from the literature and photoionization models to analyse the neon ionic
abundances obtained using both optical and mid-infrared emission-lines.
Comparing Ne++/H+ ionic abundances from distinct methods, we found that, in
average, the abundances obtained via IR emission-lines are higher than those
obtained via optical lines by a factor of 4. Photoionization models with
abundance variations along the radius of the hypothetical nebula provide a
possible explanation for a large part of the difference between ionic
abundances via optical and infrared emission-lines. Ionization Correction
Factor (ICF) for the neon is obtained from direct determinations of ionic
fractions using infrared emission-lines. A constant Ne/O ratio (logNe/O \approx
-0.70) for a large range of metallicity, independently of the ICF used to
compute the neon total abundance is derived.Comment: 17 pages, 14 figures, accepted by MNRA
X-rays as dominant excitation mechanism of [Fe ii] and H2 emission lines in active galaxies
We investigate the excitation mechanisms of near-infrared [Fe ii] and H2
emission lines observed in Active Galactic Nuclei (AGNs). We built a
photoionization model grid considering a two-component continuum, one accounts
for the Big Bump component peaking at 1Ryd and another represents the X-ray
source that dominates the continuum emission at high energies. Photoionization
models considering as ionizing source a spectral energy distribution obtained
from photometric data of the Sy 2 Mrk 1066 taken from the literature were
considered. Results of these models were compared with a large sample of
observational long-slit and Integral field Unit (IFU) spectroscopy data of the
nuclear region for a sample of active objects. We found that the correlation
between the observational [Fe ii]{\lambda}1.2570 {\mu}m/Pa{\beta} vs.
H2{\lambda}2.1218 {\mu}m/Br{\gamma} is well reproduced by our models as well as
the relationships that involve the H2 emission line ratios observed in the
spectroscopic data.We conclude that the heating by X-rays produced by active
nuclei can be considered a common and very important mechanism of excitation of
[Fe ii] and H2.Comment: 10 pages, 9 figures, accepted by MNRA
Hospital Virtual: Sistema de información clínica y telecuidado de pacientes VIH/SIDA basado en tecnologías Web 2.0
Este artículo describe el desarrollo de un nuevo sistema de información clínica y telecuidado de pacientes VIH/SIDA que se encuentra implantado en rutina clínica dentro del Servicio de Enfermedades Infecciosas del Hospital Clínic de Barcelona. El proyecto surge ante la necesidad de unificar el sistema de información departamental del servicio y un sistema de telemedicina instalado en el hospital en 2004. Para ello se han diseñado e implementado nuevas bases de datos y dos sistemas específicos para uso de profesionales y pacientes. Además, se ha realizado una integración con el Sistema de Información del Hospital (HIS) permitiendo el acceso a todos los datos requeridos de los pacientes desde una única aplicación. Este nuevo sistema está al servicio de más de 70 profesionales sanitarios que realizan una media de 150 consultas al día disponiendo de información clínica de más de 8000 pacientes
Influence of air temperature on drying kinetics and antioxidant potential of olive pomace
This work aims to evaluate the influence of olive pomace drying (a solid by-product of the olive oil industry)
on both antioxidant potential and drying kinetics. The two main fractions of olive pomace (pits, PI
and pulps + peels, P + P) were characterized by image analysis and density measurement. The drying process
was analyzed in experiments carried out at different temperatures (from 50 to 150 C) and mathematically
described from the diffusion and Weibull models. The antioxidant potential of the extracts
(ethanol water 80:20 v/v, 22 ± 1 C, 170 rpm for 24 h) obtained from the dry product was analyzed by
measuring the total phenolic content and antioxidant capacity and the main polyphenols were quantified
by HPLC DAD/MS MS.
The drying behavior of olive pomace was well described by considering the diffusion in the PI and P + P
fractions separately and the influence of temperature on effective moisture diffusivities was quantified by
an Arrhenius type equation. The antioxidant potential was only mildly influenced by the drying temperature.
However, long drying times at the highest temperature tested (150 C) significantly (p < 0.05)
increased the antioxidant potentialThe authors acknowledge the Generalitat Valenciana (PROMETEO/2010/062 and PROMETEO/2012/007) and Ministerio de Economia y Competitividad (AGL2011-29857-C03-04) for their financial support and the Ministerio de Educacion, Cultura y Deporte of Spain for the financing through the Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion.Ahmad-Qasem Mateo, MH.; Barrajón Catalán, E.; Micol, V.; Cárcel Carrión, JA.; García Pérez, JV. (2013). Influence of air temperature on drying kinetics and antioxidant potential of olive pomace. Journal of Food Engineering. 119(3):516-524. https://doi.org/10.1016/j.jfoodeng.2013.06.027S516524119
- …