1,128 research outputs found
Understanding the 8 micron vs. Pa-alpha relationship on sub-arcsecond scales in Luminous Infrared Galaxies
This work explores in detail the relation between the 8 micron and the
Pa-alpha emissions for 122 HII regions identified in a sample of 10 low-z LIRGs
with nearly constant metallicity (12 + log (O/H) ~ 8.8). We use Gemini/T-ReCS
high-spatial resolution (<~ 0.4" ~ 120 pc for the average distance of 60 Mpc of
our sample) mid-infrared imaging (at 8.7 micron or 10.3 micron) together with
HST/NICMOS continuum and Pa-alpha images. The LIRG HII regions extend the
L_8micron vs. L_Pa-alpha relation found for HII knots in the high-metallicity
SINGS galaxies by about two orders of magnitude to higher luminosities. Since
the metallicity of the LIRG sample is nearly constant, we can rule out this
effect as a cause for the scatter seen in the relationship. In turn, it is
attributed to two effects: age and PAH features. The L_8micron/L_Pa-alpha
ratio, which varies by a factor of ten for the LIRG HII regions, is reproduced
by a model with instantaneous star formation and ages ranging from ~ 4 to 7.5
Myr. The remaining dispersion around the model predictions for a given age is
probably due to differential contributions of the PAH features (the 8.6 micron,
in our case) to the 8 micron emission from galaxy to galaxy.Comment: 16 pages, 9 figures, accepted for publication in ApJ; paper with
full-resolution figures can be found at:
http://damir.iem.csic.es/extragalactic
Network-Based Methods for Approaching Human Pathologies from a Phenotypic Point of View
Network and systemic approaches to studying human pathologies are helping us to gain insight into the molecular mechanisms of and potential therapeutic interventions for human diseases, especially for complex diseases where large numbers of genes are involved. The complex human pathological landscape is traditionally partitioned into discrete “diseases”; however, that partition is sometimes problematic, as diseases are highly heterogeneous and can differ greatly from one patient to another. Moreover, for many pathological states, the set of symptoms (phenotypes) manifested by the patient is not enough to diagnose a particular disease. On the contrary, phenotypes, by definition, are directly observable and can be closer to the molecular basis of the pathology. These clinical phenotypes are also important for personalised medicine, as they can help stratify patients and design personalised interventions. For these reasons, network and systemic approaches to pathologies are gradually incorporating phenotypic information. This review covers the current landscape of phenotype-centred network approaches to study different aspects of human diseasesThis work was partially funded by The Spanish Ministry of Economy and Competitiveness with European Regional Development Fund [grant numbers PID2019-108096RB-C21 and PID2019-108096RB-C22]; the European Food Safety Authority [grant number GP/EFSA/ENCO/2020/02]; the Andalusian Government with European Regional Development Fund [grant numbers UMA18-
FEDERJA-102 and PAIDI 2020:PY20-00372]; Fundacion Progreso y Salud [grant number PI-0075-2017], also from the Andalusian Government; the Ramón Areces foundation, which funds project for the investigation of rare disease (National call for research on life and material sciences, XIX edition); the University of Malaga (Ayudas del I Plan Propio) and the Institute of Health Carlos III which funds the IMPaCT-Data project. The CIBERER is an initiative from the Institute of Health Carlos III. The conclusions, findings and opinions expressed in this scientific paper reflect only the view of the authors and not the official position of the European Food Safety Authority. Partial funding for open access charge: Universidad de Málag
MeSH indexing based on automatically generated summaries
BACKGROUND: MEDLINE citations are manually indexed at the U.S. National Library of Medicine (NLM) using as reference the Medical Subject Headings (MeSH) controlled vocabulary. For this task, the human indexers read the full text of the article. Due to the growth of MEDLINE, the NLM Indexing Initiative explores indexing methodologies that can support the task of the indexers. Medical Text Indexer (MTI) is a tool developed by the NLM Indexing Initiative to provide MeSH indexing recommendations to indexers. Currently, the input to MTI is MEDLINE citations, title and abstract only. Previous work has shown that using full text as input to MTI increases recall, but decreases precision sharply. We propose using summaries generated automatically from the full text for the input to MTI to use in the task of suggesting MeSH headings to indexers. Summaries distill the most salient information from the full text, which might increase the coverage of automatic indexing approaches based on MEDLINE. We hypothesize that if the results were good enough, manual indexers could possibly use automatic summaries instead of the full texts, along with the recommendations of MTI, to speed up the process while maintaining high quality of indexing results. RESULTS: We have generated summaries of different lengths using two different summarizers, and evaluated the MTI indexing on the summaries using different algorithms: MTI, individual MTI components, and machine learning. The results are compared to those of full text articles and MEDLINE citations. Our results show that automatically generated summaries achieve similar recall but higher precision compared to full text articles. Compared to MEDLINE citations, summaries achieve higher recall but lower precision. CONCLUSIONS: Our results show that automatic summaries produce better indexing than full text articles. Summaries produce similar recall to full text but much better precision, which seems to indicate that automatic summaries can efficiently capture the most important contents within the original articles. The combination of MEDLINE citations and automatically generated summaries could improve the recommendations suggested by MTI. On the other hand, indexing performance might be dependent on the MeSH heading being indexed. Summarization techniques could thus be considered as a feature selection algorithm that might have to be tuned individually for each MeSH heading
The test case of HD26965: difficulties disentangling weak Doppler signals from stellar activity
We report the discovery of a radial velocity signal that can be interpreted
as a planetary-mass candidate orbiting the K dwarf HD26965, with an orbital
period of 42.3640.015 days, or alternatively, as the presence of residual,
uncorrected rotational activity in the data. Observations include data from
HIRES, PFS, CHIRON, and HARPS, where 1,111 measurements were made over 16
years. Our best solution for HD26965 is consistent with a super-Earth that
has a minimum mass of 6.920.79 M orbiting at a distance of
0.2150.008 AU from its host star. We have analyzed the correlation between
spectral activity indicators and the radial velocities from each instrument,
showing moderate correlations that we include in our model. From this analysis,
we recover a 38 day signal, which matches some literature values of the
stellar rotation period. However, from independent Mt. Wilson HK data for this
star, we find evidence for a significant 42 day signal after subtraction of
longer period magnetic cycles, casting doubt on the planetary hypothesis for
this period. Although our statistical model strongly suggests that the 42-day
signal is Doppler in origin, we conclude that the residual effects of stellar
rotation are difficult to fully model and remove from this dataset,
highlighting the difficulties to disentangle small planetary signals and
photospheric noise, particularly when the orbital periods are close to the
rotation period of the star. This study serves as an excellent test case for
future works that aim to detect small planets orbiting `Sun-like' stars using
radial velocity measurements.Comment: 16 pages, 10 figures, 13 tables, accepted for publication in A
EPIC247098361b: a transiting warm Saturn on an eccentric days orbit around a star
We report the discovery of EPIC247098361b using photometric data of the
Kepler K2 satellite coupled with ground-based spectroscopic observations.
EPIC247098361b has a mass of M M, a radius of
R R, and a moderately low equilibrium temperature of
K due to its relatively large star-planet separation of
AU. EPIC247098361b orbits its bright () late F-type host star
in an eccentric orbit () every 11.2 days, and is one of only
four well characterized warm Jupiters having hosts stars brighter than .
We estimate a heavy element content of 20 7 M for
EPIC247098361b, which is consistent with standard models of giant planet
formation. The bright host star of EPIC247098361b makes this system a well
suited target for detailed follow-up observations that will aid in the study of
the atmospheres and orbital evolution of giant planets at moderate separations
from their host stars.Comment: 11 pages, 10 figures, submitted to MNRA
Integral field spectroscopy of nitrogen overabundant blue compact dwarf galaxies
We study the spatial distribution of the physical properties and of oxygen
and nitrogen abundances in three Blue Compact Dwarf Galaxiess (HS 0128+2832, HS
0837+4717 and Mrk 930) with a reported excess of N/O in order to investigate
the nature of this excess and, particularly, if it is associated with
Wolf-Rayet (WR) stars We have observed these BCDs by using PMAS integral field
spectroscopy in the optical spectral range (3700 - 6900 {\AA}), mapping their
physical-chemical properties, using both the direct method and appropriate
strong-line methods. We make a statistical analysis of the resulting
distributions and we compare them with the integrated properties of the
galaxies. Our results indicate that outer parts of the three galaxies are
placed on the "AGN-zone" of the [NII]/H{\alpha} vs. [OIII]/H{\beta} diagnostic
diagram most likely due to a high N/O combined with the excitation structure in
these regions. From the statistical analysis, it is assumed that a certain
property can be considered as spatially homogeneous (or uniform) if a normal
gaussian function fits its distribution in several regions of the galaxy.
Moreover, a disagreement between the integrated properties and the mean values
of the distribution usually appears when a gaussian does not fit the
corresponding distribution. We find that for Mrk 930, the uniformity is found
for all parameters, except for electron density and reddening. The rotation
curve together with the H{\alpha} map and UV images, reveal a perturbed
morphology and possible interacting processes. The N/O is found to be constant
in the three studied objects at spatial scales of the order of several kpc so
we conclude that the number of WR stars estimated from spectroscopy is not
sufficient to pollute the ISM and to produce the observed N/O excess in these
objectsComment: 17 pages, 14 figures, accepted for publication in Astronomy &
Astrophysic
Evaluación de la seguridad estructural de un sistema de seguimiento solar en colombia
An appropriate dimensioning of each component in a tracking solar system is needed to take maximum advantage of the solar panel. This work describes a methodology for the safety of a support structure of a photovoltaic panel with solar tracking, which is integrated into a graphical user interface-GUI written in Matlab®. In a very intuitive manner and through a friendly interactive visual tool, the GUI gathers the basic mechanical parameters that influence the safety factor of the structure, with the possibility to configure several operating conditions of the system. The results were compared to those found using finite element analysis-FEA with SolidWorks®.Para un mayor aprovechamiento de los sistemas de solares, es indispensable un adecuado dimensionamiento de cada uno de los componentes que los conforman. El presente trabajo describe una metodología para la seguridad de una estructura soporte para panel fotovoltaico con seguimiento solar y su integración a una interfaz gráfica de usuario-GUI desarrollada en Matlab®, la cual, de manera didáctica y a través de un entorno visual amigable e interactivo, reúne los parámetros mecánicos básicos que influyen en el factor de seguridad de la estructura, con la opción de adaptarse a las condiciones de operación del sistema. Usando SolidWorks®, se comparan los resultados de factor de seguridad obtenidos versus análisis de elementos finitos (FEA
Damping mechanisms for oscillations in solar prominences
Small amplitude oscillations are a commonly observed feature in
prominences/filaments. These oscillations appear to be of local nature, are
associated to the fine structure of prominence plasmas, and simultaneous flows
and counterflows are also present. The existing observational evidence reveals
that small amplitude oscillations, after excited, are damped in short spatial
and temporal scales by some as yet not well determined physical mechanism(s).
Commonly, these oscillations have been interpreted in terms of linear
magnetohydrodynamic (MHD) waves, and this paper reviews the theoretical damping
mechanisms that have been recently put forward in order to explain the observed
attenuation scales. These mechanisms include thermal effects, through
non-adiabatic processes, mass flows, resonant damping in non-uniform media, and
partial ionization effects. The relevance of each mechanism is assessed by
comparing the spatial and time scales produced by each of them with those
obtained from observations. Also, the application of the latest theoretical
results to perform prominence seismology is discussed, aiming to determine
physical parameters in prominence plasmas that are difficult to measure by
direct means.Comment: 36 pages, 16 figures, Space Science Reviews (accepted
Mapping the cold dust temperatures and masses of nearby Kingfish galaxies with Herschel
Taking advantage of the sensitivity and angular resolution of the Herschel
Space Observatory at far-infrared and submm wavelengths, we aim to characterize
the physical properties of cold dust within nearby galaxies and study the
robustness of the parameters we derive using different modified blackbody
models. For a pilot subsample of the KINGFISH program, we perform 2 temperature
fits of the Spitzer and Herschel photometric data (24 to 500um), with a warm
and a cold component, globally and in each resolution element.At global scales,
we observe ranges of values for beta_c(0.8 to 2.5) and Tc(19.1 to 25.1K).We
compute maps of our parameters with beta fixed or free to test the robustness
of the temperature and dust surface density maps we deduce. When the emissivity
is fixed, we observe temperature gradients as a function of radius.When the
emissivity is fitted as a free parameter, barred galaxies tend to have uniform
fitted emissivities.Gathering resolved elements in a Tc-beta_c diagram
underlines an anti-correlation between the two parameters.It remains difficult
to assess whether the dominant effect is the physics of dust grains, noise, or
mixing along the line of sight and in the beam. We finally observe in both
cases that the dust column density peaks in central regions of galaxies and bar
ends (coinciding with molecular gas density enhancements usually found in these
locations).We also quantify how the total dust mass varies with our assumptions
about the emissivity index as well as the influence of the wavelength coverage
used in the fits. We show that modified blackbody fits using a shallow
emissivity (beta_c < 2.0) lead to significantly lower dust masses compared to
the beta_c < 2.0 case, with dust masses lower by up to 50% if beta_c=1.5 for
instance.The working resolution affects our total dust mass estimates: masses
increase from global fits to spatially-resolved fits.Comment: 26 pages, 12 figures, 4 tables, accepted for publication in MNRAS,
2012 June 2
- …