178 research outputs found
Plant’s gypsum affinity shapes responses to specific edaphic constraints without limiting responses to other general constraints
Aims: Harsh edaphic environments harbor species with different soil affinities. Plant’s responses to specific edaphic constraints may be compromised against responses to prevalent stresses shared with other semi-arid environments. We expect that species with high edaphic affinity may show traits to overcome harsh soil properties, while species with low affinity may respond to environmental constraints shared with arid environments. Methods: We quantified the edaphic affinity of 12 plant species co-occurring in gypsum outcrops and measured traits related to plant responses to specific gypsum constraints (rooting and water uptake depth, foliar accumulation of Ca, S and Mg), and traits related to common constraints of arid environments (water use efficiency, macronutrients foliar content). Results: Plants in gypsum outcrops differed in their strategies to face edaphic limitations. A phylogenetic informed PCA segregated species based on their foliar Ca and S accumulation and greater water uptake depths, associated with plant responses to specific gypsum limitations. Species’ gypsum affinity explained this segregation, but traits related to water or nutrient use efficiency did not contribute substantially to this axis. Conclusions: Plant’s specializations to respond to specific edaphic constraints of gypsum soils do not limit their ability to deal with other non-specific environmental constraints
Apoptosis in hypertensive heart disease: a clinical approach
PURPOSE OF REVIEW: It is widely accepted that there are two principal forms of cell death, namely, necrosis and apoptosis. According to the classical view, necrosis is the major mechanism of cardiomyocyte death in cardiac diseases.
RECENT DEVELOPMENTS: In the past few years observations have been made showing that cardiomyocyte apoptosis occurs in diverse conditions including hypertensive heart disease, and that apoptosis may be a contributing cause of loss and functional abnormalities of cardiomyocytes in this condition.
SUMMARY: This review will summarize recent evidence demonstrating the potential contribution of cardiomyocyte apoptosis to heart failure in hypertensive patients. In addition, some strategies aimed to detect and prevent apoptosis of cardiomyocytes will be considered
Stellar populations of bulges at low redshift
This chapter summarizes our current understanding of the stellar population
properties of bulges and outlines important future research directions.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen
E., Peletier R., Gadotti D., Springer Publishing. 34 pages, 12 figure
DustPedia: Multiwavelength photometry and imagery of 875 nearby galaxies in 42 ultraviolet-microwave bands
Aims. The DustPedia project is capitalising on the legacy of the Herschel Space Observatory, using cutting-edge modelling techniques to study dust in the 875 DustPedia galaxies – representing the vast majority of extended galaxies within 3000 km s-1 that were observed by Herschel. This work requires a database of multiwavelength imagery and photometry that greatly exceeds the scope (in terms of wavelength coverage and number of galaxies) of any previous local-Universe survey.
Methods. We constructed a database containing our own custom Herschel reductions, along with standardised archival observations from GALEX, SDSS, DSS, 2MASS, WISE, Spitzer, and Planck. Using these data, we performed consistent aperture-matched photometry, which we combined with external supplementary photometry from IRAS and Planck.
Results. We present our multiwavelength imagery and photometry across 42 UV-microwave bands for the 875 DustPedia galaxies. Our aperture-matched photometry, combined with the external supplementary photometry, represents a total of 21 857 photometric measurements. A typical DustPedia galaxy has multiwavelength photometry spanning 25 bands. We also present the Comprehensive & Adaptable Aperture Photometry Routine (CAAPR), the pipeline we developed to carry out our aperture-matched photometry. CAAPR is designed to produce consistent photometry for the enormous range of galaxy and observation types in our data. In particular, CAAPR is able to determine robust cross-compatible uncertainties, thanks to a novel method for reliably extrapolating the aperture noise for observations that cover a very limited amount of background. Our rich database of imagery and photometry is being made available to the community
Resolved stellar population properties of PHANGS-MUSE galaxies
Analyzing resolved stellar populations across the disk of a galaxy can
provide unique insights into how that galaxy assembled its stellar mass over
its lifetime. Previous work at ~1 kpc resolution has already revealed common
features in the mass buildup (e.g., inside-out growth of galaxies). However,
even at approximate kpc scales, the stellar populations are blurred between the
different galactic morphological structures such as spiral arms, bars and
bulges. Here we present a detailed analysis of the spatially resolved star
formation histories (SFHs) of 19 PHANGS-MUSE galaxies, at a spatial resolution
of ~100 pc. We show that our sample of local galaxies exhibits predominantly
negative radial gradients of stellar age and [Z/H], consistent with previous
findings, and a radial structure that is primarily consistent with local star
formation, and indicative of inside-out formation. In barred galaxies, we find
flatter [Z/H] gradients along the semi-major axis of the bar than along the
semi-minor axis, as is expected from the radial mixing of material along the
bar. In general, the derived assembly histories of the galaxies in our sample
tell a consistent story of inside-out growth, where low-mass galaxies assembled
the majority of their stellar mass later in cosmic history than high-mass
galaxies. We also show how stellar populations of different ages exhibit
different kinematics, with younger stellar populations having lower velocity
dispersions than older stellar populations at similar galactocentric distances,
which we interpret as an imprint of the progressive dynamical heating of
stellar populations as they age. Finally, we explore how the time-averaged star
formation rate evolves with time, and how it varies across galactic disks. This
analysis reveals a wide variation of the SFHs of galaxy centers and
additionally shows that structural features become less pronounced with age.Comment: 52 pages, 48 figures, accepted for publication in A&
Diagnostic value of cerebrospinal fluid alpha-synuclein seed quantification in synucleinopathies
Several studies have confirmed the α-synuclein real-time quaking-induced conversion (RT-QuIC) assay to have high sensitivity and specificity for Parkinson's disease. However, whether the assay can be used as a robust, quantitative measure to monitor disease progression, stratify different synucleinopathies and predict disease conversion in patients with idiopathic REM sleep behaviour disorder remains undetermined. The aim of this study was to assess the diagnostic value of CSF α-synuclein RT-QuIC quantitative parameters in regard to disease progression, stratification and conversion in synucleinopathies. We performed α-synuclein RT-QuIC in the CSF samples from 74 Parkinson's disease, 24 multiple system atrophy and 45 idiopathic REM sleep behaviour disorder patients alongside 55 healthy controls, analysing quantitative assay parameters in relation to clinical data. α-Synuclein RT-QuIC showed 89% sensitivity and 96% specificity for Parkinson's disease. There was no correlation between RT-QuIC quantitative parameters and Parkinson's disease clinical scores (e.g. Unified Parkinson's Disease Rating Scale motor), but RT-QuIC positivity and some quantitative parameters (e.g. Vmax) differed across the different phenotype clusters. RT-QuIC parameters also added value alongside standard clinical data in diagnosing Parkinson's disease. The sensitivity in multiple system atrophy was 75%, and CSF samples showed longer T50 and lower Vmax compared to Parkinson's disease. All RT-QuIC parameters correlated with worse clinical progression of multiple system atrophy (e.g. change in Unified Multiple System Atrophy Rating Scale). The overall sensitivity in idiopathic REM sleep behaviour disorder was 64%. In three of the four longitudinally followed idiopathic REM sleep behaviour disorder cohorts, we found around 90% sensitivity, but in one sample (DeNoPa) diagnosing idiopathic REM sleep behaviour disorder earlier from the community cases, this was much lower at 39%. During follow-up, 14 of 45 (31%) idiopathic REM sleep behaviour disorder patients converted to synucleinopathy with 9/14 (64%) of convertors showing baseline RT-QuIC positivity. In summary, our results showed that α-synuclein RT-QuIC adds value in diagnosing Parkinson's disease and may provide a way to distinguish variations within Parkinson's disease phenotype. However, the quantitative parameters did not correlate with disease severity in Parkinson's disease. The assay distinguished multiple system atrophy patients from Parkinson's disease patients and in contrast to Parkinson's disease, the quantitative parameters correlated with disease progression of multiple system atrophy. Our results also provided further evidence for α-synuclein RT-QuIC having potential as an early biomarker detecting synucleinopathy in idiopathic REM sleep behaviour disorder patients prior to conversion. Further analysis of longitudinally followed idiopathic REM sleep behaviour disorder patients is needed to better understand the relationship between α-synuclein RT-QuIC signature and the progression from prodromal to different synucleinopathies
Variations in the plane across galactic environments in PHANGS galaxies
There exists some consensus that stellar mass surface density ()
and molecular gas mass surface density () are the main
quantities responsible for locally setting the star formation rate. This
regulation is inferred from locally resolved scaling relations between these
two quantities and the star formation rate surface density (). However, the universality of these relations is debated. Here, we probe
the interplay between these three quantities across different galactic
environments at a spatial resolution of 150 pc. We perform a hierarchical
Bayesian linear regression to find the best set of parameters , , and that describe the star-forming plane conformed by
these quantities, such that , and explore variations in
the determined parameters across galactic environments, focusing our analysis
on the and slopes. We find signs of variations in the
posterior distributions of and across different galactic
environments. Bars show the most negative value of , a sign of longer
depletion times, while spiral arms show the highest among all
environments. We conclude that systematic variations in the interplay of
, and across galactic
environments exist at a spatial resolution of 150 pc, and we interpret these
variations as produced by an additional mechanism regulating the formation of
stars that is not captured by either or . We
find that these variations correlate with changes in the star formation
efficiency across environments, which could be linked to the dynamical state of
the gas that prevents it from collapsing and forming stars, or to changes in
the molecular gas fraction.Comment: 21 pages, 16 figures, accepted for publication in A&
Inner bars also buckle. The MUSE TIMER view of the double-barred galaxy NGC 1291
Double bars are thought to be important features for secular evolution in the central regions of galaxies. However, observational evidence about their origin and evolution is still scarce. We report on the discovery of the first Box/Peanut (B/P) structure in an inner bar detected in the face-on galaxy NGC 1291. We use the integral field data obtained from the MUSE spectrograph within the TIMER project. The B/P structure is detected as bi-symmetric minima of the h_4 moment of the line-of-sight velocity distribution along the major axis of the inner bar, as expected from numerical simulations. Our observations demonstrate that inner bars can follow a similar evolutionary path as outer bars, undergoing buckling instabilities. They also suggest that inner bars are long-lived structures, thus imposing tight constraints to their possible formation mechanisms
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