2,197 research outputs found
The continuous star formation history of a giant HII region in M101
We present results about the star formation process in the giant HII region
NGC 5471 in the outskirts of M101. From resolved HST/WPFC2 photometry we find
that star formation has been going for the last 70 Myr. We further compare
previous results from integrated infrared-optical photometry with the stellar
resolved CMD and we discuss the star formation properties of this region and
its individual knots, as well as characterizing the different stellar content.
This result has very important consequences in our understanding of the burst
versus continuous star formation activity in spiral galaxies.Comment: 2 pages, 2 figures. Proceeding of the conference From Stars to
Galaxies: Building the pieces to build up the Universe (Venice, Italy
Resolving the age bimodality of galaxy stellar populations on kpc scales
Galaxies in the local Universe are known to follow bimodal distributions in
the global stellar populations properties. We analyze the distribution of the
local average stellar-population ages of 654,053 sub-galactic regions resolved
on ~1-kpc scales in a volume-corrected sample of 394 galaxies, drawn from the
CALIFA-DR3 integral-field-spectroscopy survey and complemented by SDSS imaging.
We find a bimodal local-age distribution, with an old and a young peak
primarily due to regions in early-type galaxies and star-forming regions of
spirals, respectively. Within spiral galaxies, the older ages of bulges and
inter-arm regions relative to spiral arms support an internal age bimodality.
Although regions of higher stellar-mass surface-density, mu*, are typically
older, mu* alone does not determine the stellar population age and a bimodal
distribution is found at any fixed mu*. We identify an "old ridge" of regions
of age ~9 Gyr, independent of mu*, and a "young sequence" of regions with age
increasing with mu* from 1-1.5 Gyr to 4-5 Gyr. We interpret the former as
regions containing only old stars, and the latter as regions where the relative
contamination of old stellar populations by young stars decreases as mu*
increases. The reason why this bimodal age distribution is not inconsistent
with the unimodal shape of the cosmic-averaged star-formation history is that
i) the dominating contribution by young stars biases the age low with respect
to the average epoch of star formation, and ii) the use of a single average age
per region is unable to represent the full time-extent of the star-formation
history of "young-sequence" regions.Comment: 17 pages, 11 figures, MNRAS accepte
Stellar Population gradients in galaxy discs from the CALIFA survey
While studies of gas-phase metallicity gradients in disc galaxies are common,
very little has been done in the acquisition of stellar abundance gradients in
the same regions. We present here a comparative study of the stellar
metallicity and age distributions in a sample of 62 nearly face-on, spiral
galaxies with and without bars, using data from the CALIFA survey. We measure
the slopes of the gradients and study their relation with other properties of
the galaxies. We find that the mean stellar age and metallicity gradients in
the disc are shallow and negative. Furthermore, when normalized to the
effective radius of the disc, the slope of the stellar population gradients
does not correlate with the mass or with the morphological type of the
galaxies. Contrary to this, the values of both age and metallicity at 2.5
scale-lengths correlate with the central velocity dispersion in a similar
manner to the central values of the bulges, although bulges show, on average,
older ages and higher metallicities than the discs. One of the goals of the
present paper is to test the theoretical prediction that non-linear coupling
between the bar and the spiral arms is an efficient mechanism for producing
radial migrations across significant distances within discs. The process of
radial migration should flatten the stellar metallicity gradient with time and,
therefore, we would expect flatter stellar metallicity gradients in barred
galaxies. However, we do not find any difference in the metallicity or age
gradients in galaxies with without bars. We discuss possible scenarios that can
lead to this absence of difference.Comment: 24 pages, 17 figures, accepted for publication in A&
microRNA Expression and Its Association With Disability and Brain Atrophy in Multiple Sclerosis Patients Treated With Glatiramer Acetate.
Background: MicroRNAs are small non-coding RNA that regulate gene expression at a
post-transcriptional level affecting several cellular processes including inflammation,
neurodegeneration and remyelination. Different patterns of miRNAs expression have
been demonstrated in multiple sclerosis compared to controls, as well as in different
courses of the disease. For these reason they have been postulated as promising
biomarkers candidates in multiple sclerosis.
Objective: To correlate serum microRNAs profile expression with disability, cognitive
functioning and brain volume in patients with remitting-relapsing multiple sclerosis.
Methods: Cross-sectional study in relapsing-remitting multiple sclerosis patients treated
with glatiramer acetate. Disability was measured with Expanded Disability Status Scale
(EDSS) and cognitive function was studied with Symbol Digit Modalities Test (SDMT).
Brain volume was analyzed with automatic software NeuroQuant®
.
Results: We found an association between miR.146a.5p (rs:0.434, p=0.03) and miR.9.5p
(rs:0.516, p=0.028) with EDSS; and miR-146a.5p (rs:-0.476, p=0.016) and miR-126.3p
(rs:-0.528, p=0.007) with SDMT. Regarding to the brain volume, miR.9.5p correlated with
thalamus (rs:-0.545, p=0.036); miR.200c.3p with pallidum (rs:-0.68, p=0.002) and
cerebellum (rs:-0.472, p=0.048); miR-138.5p with amygdala (rs:0.73, p=0.016) and
pallidum (rs:0.64, p=0.048); and miR-223.3p with caudate (rs:0.46, p=0.04).
Conclusions: These data support the hypothesis of microRNA as potential biomarkers in
this disease. More studies are needed to validate these results and to better understand
the role of microRNAs in the pathogenesis, monitoring and therapeutic response of
multiple sclerosis.post-print1410 K
Ionized gas kinematics of galaxies in the CALIFA survey I: Velocity fields, kinematic parameters of the dominant component, and presence of kinematically distinct gaseous systems
This work provides an overall characterization of the kinematic behavior of
the ionized gas of the galaxies included in the Calar Alto Legacy Integral
field Area (CALIFA), offering kinematic clues to potential users of this survey
for including kinematical criteria for specific studies. From the first 200
galaxies observed by CALIFA, we present the 2D kinematic view of the 177
galaxies satisfying a gas detection threshold. After removing the stellar
contribution, we used the cross-correlation technique to obtain the radial
velocity of the dominant gaseous component. The main kinematic parameters were
directly derived from the radial velocities with no assumptions on the internal
motions. Evidence of the presence of several gaseous components with different
kinematics were detected by using [OIII] profiles. Most objects in the sample
show regular velocity fields, although the ionized-gas kinematics are rarely
consistent with simple coplanar circular motions. 35% of the objects present
evidence of a displacement between the photometric and kinematic centers larger
than the original spaxel radii. Only 17% of the objects in the sample exhibit
kinematic lopsidedness when comparing receding and approaching sides of the
velocity fields, but most of them are interacting galaxies exhibiting nuclear
activity. Early-type galaxies in the sample present clear photometric-kinematic
misaligments. There is evidence of asymmetries in the emission line profiles
suggesting the presence of kinematically distinct gaseous components at
different distances from the nucleus. This work constitutes the first
determination of the ionized gas kinematics of the galaxies observed in the
CALIFA survey. The derived velocity fields, the reported kinematic
peculiarities and the identification of the presence of several gaseous
components might be used as additional criteria for selecting galaxies for
specific studies.Comment: 38 pages, 16 figures, 4 tables. Paper accepted for publication in A&
Lifestyles, arterial aging, and its relationship with the intestinal and oral microbiota (MIVAS III study): a research protocol for a cross-sectional multicenter study
The microbiota is increasingly recognized as a significant factor in the pathophysiology of many diseases, including cardiometabolic diseases, with lifestyles probably exerting the greatest influence on the composition of the human microbiome. The main objectives of the study are to analyze the association of lifestyles (diet, physical activity, tobacco, and alcohol) with the gut and oral microbiota, arterial aging, and cognitive function in subjects without cardiovascular disease in the Iberian Peninsula. In addition, the study will examine the mediating role of the microbiome in mediating the association between lifestyles and arterial aging as well as cognitive function.Methods and analysisMIVAS III is a multicenter cross-sectional study that will take place in the Iberian Peninsula. One thousand subjects aged between 45 and 74 years without cardiovascular disease will be selected. The main variables are demographic information, anthropometric measurements, and habits (tobacco and alcohol). Dietary patterns will be assessed using a frequency consumption questionnaire (FFQ) and the Mediterranean diet adherence questionnaire. Physical activity levels will be evaluated using the International Physical Activity Questionnaire (IPAQ), Marshall Questionnaire, and an Accelerometer (Actigraph). Body composition will be measured using the Inbody 230 impedance meter. Arterial aging will be assessed through various means, including measuring medium intimate carotid thickness using the Sonosite Micromax, conducting analysis with pulse wave velocity (PWA), and measuring pulse wave velocity (cf-PWV) using the Sphygmocor System. Additional cardiovascular indicators such as Cardio Ankle Vascular Index (CAVI), ba-PWV, and ankle-brachial index (Vasera VS-2000®) will also be examined. The study will analyze the intestinal microbiota using the OMNIgene GUT kit (OMR−200) and profile the microbiome through massive sequencing of the 16S rRNA gene. Linear discriminant analysis (LDA), effect size (LEfSe), and compositional analysis, such as ANCOM-BC, will be used to identify differentially abundant taxa between groups. After rarefying the samples, further analyses will be conducted using MicrobiomeAnalyst and R v.4.2.1 software. These analyses will include various aspects, such as assessing α and β diversity, conducting abundance profiling, and performing clustering analysis.DiscussionLifestyle acts as a modifier of microbiota composition. However, there are no conclusive results demonstrating the mediating effect of the microbiota in the relationship between lifestyles and cardiovascular diseases. Understanding this relationship may facilitate the implementation of strategies for improving population health by modifying the gut and oral microbiota
Transcriptional network analysis in frontal cortex in Lewy body diseases with focus on dementia with Lewy bodies
The present study investigates global transcriptional changes in frontal cortex area 8 in incidental Lewy Body disease (iLBD), Parkinson disease (PD) and Dementia with Lewy bodies (DLB). We identified different co-expressed gene sets associated with disease stages, and gene ontology categories enriched in gene modules and differentially expressed genes including modules or gene clusters correlated to iLBD comprising upregulated dynein genes and taste receptors, and down-regulated innate inflammation. Focusing on DLB, we found modules with genes significantly enriched in functions related to RNA and DNA production, mitochondria and energy metabolism, purine metabolism, chaperone and protein folding system, and synapses and neurotransmission (particularly the GABAergic system). The expression of more than fifty selected genes was assessed with RT-qPCR. Our findings provide, for the first time, evidence of molecular cortical alterations in iLBD and involvement of several key metabolic pathways and gene hubs in DLB which may underlie cognitive impairment and dementia. Key words: Lewy body diseases, dementia with Lewy bodies, cerebral cortex, transcriptome, mitochondria, synapses, neurotransmission, GABA, purine metabolism, chaperones, dynein, axonema, taste receptors
The Mass-Metallicity relation explored with CALIFA: I. Is there a dependence on the star formation rate?
We present the results on the study of the global and local M-Z relation
based on the first data available from the CALIFA survey (150 galaxies). This
survey provides integral field spectroscopy of the complete optical extent of
each galaxy (up to 2-3 effective radii), with enough resolution to separate
individual HII regions and/or aggregations. Nearly 3000 individual HII
regions have been detected. The spectra cover the wavelength range between
[OII]3727 and [SII]6731, with a sufficient signal-to-noise to derive the oxygen
abundance and star-formation rate associated with each region. In addition, we
have computed the integrated and spatially resolved stellar masses (and surface
densities), based on SDSS photometric data. We explore the relations between
the stellar mass, oxygen abundance and star-formation rate using this dataset.
We derive a tight relation between the integrated stellar mass and the
gas-phase abundance, with a dispersion smaller than the one already reported in
the literature (0.07 dex). Indeed, this
dispersion is only slightly larger than the typical error derived for our
oxygen abundances. However, we do not find any secondary relation with the
star-formation rate, other than the one induced due to the primary relation of
this quantity with the stellar mass. We confirm the result using the 3000
individual HII regions, for the corresponding local relations.
Our results agree with the scenario in which gas recycling in galaxies, both
locally and globally, is much faster than other typical timescales, like that
of gas accretion by inflow and/or metal loss due to outflows. In essence,
late-type/disk dominated galaxies seem to be in a quasi-steady situation, with
a behavior similar to the one expected from an instantaneous
recycling/closed-box model.Comment: 19 Pages, 8 figures, Accepted for Publishing in Astronomy and
Astrophysics (A&A
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