127 research outputs found
IMF - metallicity: a tight local relation revealed by the CALIFA survey
Variations in the stellar initial mass function (IMF) have been invoked to
explain the spectroscopic and dynamical properties of early-type galaxies.
However, no observations have yet been able to disentangle the physical driver.
We analyse here a sample of 24 early-type galaxies drawn from the CALIFA
survey, deriving in a homogeneous way their stellar population and kinematic
properties. We find that the local IMF is tightly related to the local
metallicity, becoming more bottom-heavy towards metal-rich populations. Our
result, combined with the galaxy mass-metallicity relation, naturally explains
previous claims of a galaxy mass-IMF relation, derived from non-IFU spectra. If
we assume that - within the star formation environment of early-type galaxies -
metallicity is the main driver of IMF variations, a significant revision of the
interpretation of galaxy evolution observables is necessary.Comment: Accepted for publication in ApJL. 6 pages, 4 figure
Assessment of acute-phase protein response associated with the different pathological forms of bovine paratuberculosis
11 páginas, 1 tabla.In this study, the concentrations of two acute-phase proteins (APPs), haptoglobin (Hp)
and serum amyloid A (SAA), were quantitatively assessed in serum samples from cattle naturally
infected with paratuberculosis (PTB). APP profiles were compared across 190 animals classified
according to the different pathological forms associated with infection: uninfected (n = 59), with
focal lesions (n = 73), multifocal lesions (n = 19), and diffuse paucibacillary (n = 11) and diffuse
multibacillary lesions (n = 28). Our results showed a significant increase in both APPs in infected
animals compared to the control group, with differences depending on the type of lesion. Hp and SAA
levels were increased significantly in all infected animals, except in cows with diffuse multibacillary
lesions that showed similar values to non-infected animals. The expression pattern of both APPs
was similar and negatively correlated with the antibody levels against PTB. These results indicate
that the release of Hp and SAA is related to the presence of PTB lesions associated with a high
cell-mediated immune response and a lower bacterial load, suggesting that the pro-inflammatory
cytokines that are associated with these forms are the main stimulus for their synthesis. These
molecules could show some potential to be used as putative biomarkers of PTB infection, particularly
for the identification of subclinical animals showing pathological forms related to latency or resistance
to the development of advanced lesions.This study was funded by grants RTI2018-099496-B-I00 from the Spanish Ministry of Science and
Innovation and LE259/P18 from “Junta de Castilla y León”
Dietary supplemental plant oils reduce methanogenesis from anaerobic microbial fermentation in the rumen
Ruminants contribute to the emissions of greenhouse gases, in particular methane, due to the microbial anaerobic fermentation of feed in the rumen. The rumen simulation technique was used to investigate the effects of the addition of different supplemental plant oils to a high concentrate diet on ruminal fermentation and microbial community composition. The control (CTR) diet was a high-concentrate total mixed ration with no supplemental oil. The other experimental diets were supplemented with olive (OLV), sunflower (SFL) or linseed (LNS) oils at 6%. Rumen digesta was used to inoculate the fermenters, and four fermentation units were used per treatment. Fermentation end-products, extent of feed degradation and composition of the microbial community (qPCR) in digesta were determined. Compared with the CTR diet, the addition of plant oils had no significant (P > 0.05) effect on ruminal pH, substrate degradation, total volatile fatty acids or microbial protein synthesis. Gas production from the fermentation of starch or cellulose were decreased by oil supplementation. Methane production was reduced by 21–28% (P < 0.001), propionate production was increased (P < 0.01), and butyrate and ammonia outputs and the acetate to propionate ratio were decreased (P < 0.001) with oil-supplemented diets. Addition of 6% OLV and LNS reduced (P < 0.05) copy numbers of total bacteria relative to the control. In conclusion, the supplementation of ruminant diets with plant oils, in particular from sunflower or linseed, causes some favorable effects on the fermentation processes. The addition of vegetable oils to ruminant mixed rations will reduce methane production increasing the formation of propionic acid without affecting the digestion of feed in the rumen. Adding vegetable fats to ruminant diets seems to be a suitable approach to decrease methane emissions, a relevant cleaner effect that may contribute to alleviate the environmental impact of ruminant production
Stellar populations of galaxies in the ALHAMBRA survey up to . I. MUFFIT: A Multi-Filter Fitting code for stellar population diagnostics
We present MUFFIT, a new generic code optimized to retrieve the main stellar
population parameters of galaxies in photometric multi-filter surveys, and we
check its reliability and feasibility with real galaxy data from the ALHAMBRA
survey. Making use of an error-weighted -test, we compare the
multi-filter fluxes of galaxies with the synthetic photometry of mixtures of
two single stellar populations at different redshifts and extinctions, to
provide through a Monte Carlo method the most likely range of stellar
population parameters (mainly ages and metallicities), extinctions, redshifts,
and stellar masses. To improve the diagnostic reliability, MUFFIT identifies
and removes from the analysis those bands that are significantly affected by
emission lines. We highlight that the retrieved age-metallicity locus for a
sample of early-type galaxies in ALHAMBRA at different stellar
mass bins are in very good agreement with the ones from SDSS spectroscopic
diagnostics. Moreover, a one-to-one comparison between the redshifts, ages,
metallicities, and stellar masses derived spectroscopically for SDSS and by
MUFFIT for ALHAMBRA reveals good qualitative agreements in all the parameters.
In addition, and using as input the results from photometric-redshift codes,
MUFFIT improves the photometric-redshift accuracy by -, and it
also detects nebular emissions in galaxies, providing physical information
about their strengths. Our results show the potential of multi-filter galaxy
data to conduct reliable stellar population studies with the appropiate
analysis techniques, as MUFFIT.Comment: 31 pages, 18 figures, accepted for publication in A&
Stellar populations of galaxies in the ALHAMBRA survey up to . II. Stellar content of quiescent galaxies within the dust-corrected stellar masscolour and the colourcolour diagrams
Our aim is to determine the distribution of stellar population parameters
(extinction, age, metallicity, and star formation rate) of quiescent galaxies
within the rest-frame stellar masscolour and colourcolour diagrams
corrected for extinction up to . These novel diagrams reduce the
contamination in samples of quiescent galaxies owing to dust-reddened galaxies,
and they provide useful constraints on stellar population parameters. We set
constraints on the stellar population parameters of quiescent galaxies
combining the ALHAMBRA multi-filter photo-spectra with our SED-fitting code
MUFFIT, making use of composite stellar population models. The extinction
obtained by MUFFIT allowed us to remove dusty star-forming (DSF) galaxies from
the sample of red galaxies. The distributions of stellar population
parameters across these rest-frame diagrams are revealed after the dust
correction and are fitted by the LOESS method to reduce uncertainty effects.
Quiescent galaxy samples defined via classical diagrams are typically
contaminated by a % fraction of DSF galaxies. A significant part of the
galaxies in the green valley are actually obscured star-forming galaxies
(%). Consequently, the transition of galaxies from the blue cloud to
the red sequence, and hence the related mechanisms for quenching, seems to be
much more efficient and faster than previously reported. The rest-frame stellar
masscolour and colourcolour diagrams are useful for constraining
the age, metallicity, extinction, and star formation rate of quiescent galaxies
by only their redshift, rest-frame colours, and/or stellar mass. Dust
correction plays an important role in understanding how quiescent galaxies are
distributed in these diagrams and is key to performing a pure selection of
quiescent galaxies via intrinsic colours.Comment: (37 pages, 29 figures, accepted for publication in A&A
HST/ACS observations of shell galaxies: inner shells, shell colours and dust
AIM:Learn more about the origin of shells and dust in early type galaxies.
METHOD: V-I colours of shells and underlying galaxies are derived, using HST
Advanced Camera for Surveys (ACS) data. A galaxy model is made locally in
wedges and subtracted to determine shell profiles and colours. We applied
Voronoi binning to our data to get smoothed colour maps of the galaxies.
Comparison with N-body simulations from the literature gives more insight to
the origin of the shell features. Shell positions and dust characteristics are
inferred from model galaxy subtracted images. RESULT: The ACS images reveal
shells well within the effective radius in some galaxies (at 1.7 kpc in the
case of NGC 5982). In some cases, strong nuclear dust patches prevent detection
of inner shells. Most shells have colours which are similar to the underlying
galaxy. Some inner shells are redder than the galaxy. All six shell galaxies
show out of dynamical equilibrium dust features, like lanes or patches, in
their central regions. Our detection rate for dust in the shell ellipticals is
greater than that found from HST archive data for a sample of normal early-type
galaxies, at the 95% confidence level. CONCLUSIONS: The merger model describes
better the shell distributions and morphologies than the interaction model. Red
shell colours are most likely due to the presence of dust and/or older stellar
populations. The high prevalence and out of dynamical equilibrium morphologies
of the central dust features point towards external influences being
responsible for visible dust features in early type shell galaxies. Inner
shells are able to manifest themselves in relatively old shell systems.Comment: accepted by A&A; 36 Figures, 25 pages. A version with full resolution
Figures can be found here: http://www.astro.rug.nl/~sikkema/shells.p
On the buildup of massive early-type galaxies at z<~1. I- Reconciling their hierarchical assembly with mass-downsizing
Several studies have tried to ascertain whether or not the increase in
abundance of the early-type galaxies (E-S0a's) with time is mainly due to major
mergers, reaching opposite conclusions. We have tested it directly through
semi-analytical modelling, by studying how the massive early-type galaxies with
log(M_*/Msun)>11 at z~0 (mETGs) would have evolved backwards-in-time, under the
hypothesis that each major merger gives place to an early-type galaxy. The
study was carried out just considering the major mergers strictly reported by
observations at each redshift, and assuming that gas-rich major mergers
experience transitory phases of dust-reddened, star-forming galaxies (DSFs).
The model is able to reproduce the observed evolution of the galaxy LFs at
z<~1, simultaneously for different rest-frame bands (B, I, and K) and for
different selection criteria on color and morphology. It also provides a
framework in which apparently-contradictory results on the recent evolution of
the luminosity function (LF) of massive, red galaxies can be reconciled, just
considering that observational samples of red galaxies can be significantly
contaminated by DSFs. The model proves that it is feasible to build up ~50-60%
of the present-day mETG population at z<~1 and to reproduce the observational
excess by a factor of ~4-5 of late-type galaxies at 0.8<z<1 through the
coordinated action of wet, mixed, and dry major mergers, fulfilling global
trends that are in general agreement with mass-downsizing. The bulk of this
assembly takes place during ~1 Gyr elapsed at 0.8<z<1. The model suggests that
major mergers have been the main driver for the observational migration of mass
from the massive-end of the blue galaxy cloud to that of the red sequence in
the last ~8 Gyr.(Abridged)Comment: Accepted for publication in Astronomy & Astrophysics; 21 pages, 8
figures. Minor corrections included, shortened title. Results and conclusions
unchange
Comparación de métodos para el seguimiento de las poblaciones de comadreja Mustela nivalis en ambientes agrícolas
La comadreja Mustela nivalis es un pequeño carnívoro especializado en el consumo de micromamíferos. En la Península Ibérica hay muy poca información sobre esta especie, siendo especialmente interesante el estudio de su papel en la regulación de la dinámica poblacional de los micromamíferos. Algunas especies alcanzan eventualmente elevadas densidades en ambientes agrícolas, generando notable alarma social ya que pueden mermar significativamente la producción agrícola. Cualquier estudio de esta naturaleza requiere de métodos efectivos de seguimiento a largo plazo de las poblaciones de este mustélido.
En este trabajo evaluamos la eficacia y eficiencia de cuatro metodologías para detectar comadrejas en ambientes agrarios: captura en vivo, trampas de huellas, trampas de pelo y cámaras-trampa. El estudio se desarrolló en dos localidades agrícolas de la meseta Castellano-Leonesa. Se hicieron dos muestreos por localidad, en otoño y primavera de 2016/2017. En cada localidad seleccionamos 10 lindes de ~400 m de longitud, donde se instalaron de forma alterna y equidistante: 6 trampas de captura, 2 trampas de huellas, 2 trampas de pelos y 1 cámara-trampa, que estuvieron activos entre 9-10 días. Se usó carne de pollo y topillo Microtus arvalis como cebo.
Se detectó la presencia de comadrejas con alguna de las metodologías en el 38% de las lindes muestreadas (ocupación estimada), con un total de 29 detecciones (13 otoño/16 primavera). El trampeo en vivo detectó la presencia en el 80% de las lindes positivas, las trampas de huella en el 33%, las cámaras-trampa en el 20% y las trampas de pelo en el 6%. La ocupación estimada estuvo relacionada positivamente con las tasas de detección (detecciones/100 trampas-día) del trampeo en vivo y de las trampas de huellas pero no con las de cámaras-trampa y trampas de pelo. Al tener en cuenta el esfuerzo (trampas-día), las trampas de pelo fueron el método menos eficiente para detectar comadrejas. Estos resultados indican que, con esfuerzos similares, las trampas de huellas y las cámaras-trampa pueden ser tan eficaces como el trampeo en vivo para detectar comadrejas en ambientes agrícolas con condiciones similares a las de nuestro estudio.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
Pleural cancer mortality in Spain: time-trends and updating of predictions up to 2020
Background
A total of 2,514,346 metric tons (Mt) of asbestos were imported into Spain from 1906 until the ban on asbestos in 2002. Our objective was to study pleural cancer mortality trends as an indicator of mesothelioma mortality and update mortality predictions for the periods 2011–2015 and 2016–2020 in Spain.Methods
Log-linear Poisson models were fitted to study the effect of age, period of death and birth cohort (APC) on mortality trends. Change points in cohort- and period-effect curvatures were assessed using segmented regression. Fractional power-link APC models were used to predict mortality until 2020. In addition, an alternative model based on national asbestos consumption figures was also used to perform long-term predictions.Results
Pleural cancer deaths increased across the study period, rising from 491 in 1976–1980 to 1,249 in 2006–2010. Predictions for the five-year period 2016–2020 indicated a total of 1,319 pleural cancer deaths (264 deaths/year). Forecasts up to 2020 indicated that this increase would continue, though the age-adjusted rates showed a levelling-off in male mortality from 2001 to 2005, corresponding to the lower risk in post-1960 generations. Among women, rates were lower and the mortality trend was also different, indicating that occupational exposure was possibly the single factor having most influence on pleural cancer mortality.Conclusion
The cancer mortality-related consequences of human exposure to asbestos are set to persist and remain in evidence until the last surviving members of the exposed cohorts have disappeared. It can thus be assumed that occupationally-related deaths due to pleural mesothelioma will continue to occur in Spain until at least 2040.The study was partially supported by a research grant from the Spanish Health Research Fund (FIS PI11/00871) and the HAR2009-07543 project of the Ministry of Science and Innovation. The Department of Labour of the Government of Catalonia provided the asbestos consumption data
- …