957 research outputs found
Preliminary effects of fertilization on ecochemical soil condition in mature spruce stands experiencing dieback in the Beskid Śla̧ski and Żywiecki Mountains, Poland
In recent years, there has been the phenomena of spruce dieback in Europe. Significant areas of spruce low mortality now cover both sides of the Polish southern border. We evaluated ecochemical parameters influencing the heavy dieback occurring in mature spruce stands in the Polish Carpathian Mountains. Dolomite, magnesite and serpentinite fertilizers were applied to experimental plots located in 100-year-old stands in the autumn of 2008. The experimental plots were located in the mid-elevational forest zone (900-950 m) on two nappes of the flysch Carpathians: Magura (Ujsoły Forest District) and Silesian (Wisła Forest District). The saturation of the studied soils demonstrates moderate resilience of soils in Wisła Forest District in relation to acid load and high flexibility of the Ujsoły soils. After application of the fertilizers, an increase of Mg, Ca and Mb was noted in the soil solution, determined in the overlaying highly acidic organic horizons through the ion-exchange buffering mechanism of highly protonated functional groups with high buffering capacity. Magnesium concentration increased following fertilization, presenting a potential improvement of forest growth capacity without the hazard of adverse side effects of liming. Aluminium stress in old spruce is unlikely, while trees in the control plots in Wisła Forest District may already be sensitive to aluminium stress. Serpentinite fertilization improved the supply of soils in magnesium without causing significant changes in the pH of the soil. Such changes in the pH were found in dolomite and magnesite fertilizer. © The Author(s) 2014
MUSE observations of the giant low surface brightness galaxy Malin 1: Numerous HII regions, star formation rate, metallicity, and dust attenuation
Giant low-surface brightness (GLSB) galaxies are an extreme class of objects
with very faint and extended gas-rich disks. Malin 1 is the largest GLSB galaxy
known to date, but its formation is still poorly understood. We use VLT/MUSE
IFU spectroscopic observations of Malin 1 to reveal, for the first time, the
presence of H emission distributed across numerous regions along its
disk, up to radial distances of 100 kpc. We made an estimate of the dust
attenuation using the Balmer decrement and found that Malin 1 has a mean
H attenuation of 0.36 mag. We observe a steep decline in the star
formation rate surface density () within the inner 20 kpc,
followed by a shallow decline in the extended disk. Similarly, the gas phase
metallicity we estimated shows a steep gradient in the inner 20 kpc, followed
by a flattening of the metallicity in the extended disk with a relatively high
value of 0.6 . We found that the normalized abundance gradient
of the inner disk is similar to values found in normal galaxies but with an
extreme value in the extended disk. A comparison of the star formation rate
surface density and gas surface density shows that, unlike normal disk galaxies
or other LSBs, Malin 1 exhibits a very low star formation efficiency. Owing to
the detection of emission lines over a large part of the disk of Malin 1, this
work sheds light on the star formation processes in this unique galaxy,
highlighting its extended star-forming disk, dust attenuation, almost flat
metallicity distribution in the outer disk, and exceptionally low
star-formation efficiency. Our findings contribute to a more detailed
understanding of the formation of the giant disk of Malin 1 and also constrain
possible proposed scenarios on the nature of GLSB galaxies in general.Comment: 12 pages, 9 figures, accepted for publication in A&
Preliminary Effects of Fertilization on Ecochemical Soil Condition in Mature Spruce Stands Experiencing Dieback in the Beskid Śląski and Żywiecki Mountains, Poland
Late percutaneous coronary intervention for an occluded infarct-related artery in patients with preserved infarct zone viability: A pooled analysis of cardiovascular magnetic resonance studies
Background: The results of clinical trials assessing the effect of late opening of infarct-related artery (IRA) on left ventricular ejection fraction (LVEF) and size in stable patients are equivocal, which may be related to the fact that the presence of viability was not a requirement for randomization in these trials. The aim of the study was to assess the influence of late percutaneous coronary intervention (PCI) with optimal medical therapy (OMT) vs. OMT alone on cardiac function and remodeling in patients presenting infarct zone with preserved viability on cardiovascular magnetic resonance (CMR).Methods: The analysis included pooled data of 43 patients from 3 randomized studies. All patients underwent CMR before randomization, but only in 1 previously unpublished study was preserved viability required for randomization to treatment. Follow-up CMR was performed after 6–12 months.Results: Late PCI with OMT led to improved LVEF (+5 ± 7% vs. –1 ± 6%, p = 0.005), decreased left ventricular end-systolic volume (–11 ± 19 mL vs. 12 ± 40 mL, p = 0.02) and a trend towards a decrease in end-diastolic volume (–7 ± 27 mL vs. 15 ± 47 mL, p = 0.07) in comparison to OMT alone. Increased LVEF and decreased left ventricular volumes were observed after the analysis was restricted to patients with left anterior descending artery (LAD) occlusion.Conclusions: In patients with the presence of infarct zone viability, OMT with late PCI for an occluded IRA (particularly LAD) is associated with improvement of left ventricular systolic function and size over OMT alone
The VIMOS Public Extragalactic Redshift Survey (VIPERS). Exploring the dependence of the three-point correlation function on stellar mass and luminosity at 0.5<z<1.1
The three-point correlation function (3PCF) is a powerful probe to
investigate the clustering of matter in the Universe in a complementary way
with respect to lower-order statistics, providing additional information with
respect to the two-point correlation function and allowing us to shed light on
biasing, nonlinear processes, and deviations from Gaussian statistics. In this
paper, we analyse the first data release of the VIMOS Public Extragalactic
Redshift Survey (VIPERS), determining the dependence of the three-point
correlation function on luminosity and stellar mass at . We
exploit the VIPERS Public Data Release 1, consisting of more than 50,000
galaxies with B-band magnitudes in the range and stellar masses in the range
. We measure both the
connected 3PCF and the reduced 3PCF in redshift space, probing different
configurations and scales, in the range [Mpc/h]. We find a
significant dependence of the reduced 3PCF on scales and triangle shapes, with
stronger anisotropy at larger scales ( Mpc/h) and an almost flat trend
at smaller scales, Mpc/h. Massive and luminous galaxies present a
larger connected 3PCF, while the reduced 3PCF is remarkably insensitive to
magnitude and stellar masses in the range we explored. These trends, already
observed at low redshifts, are confirmed for the first time to be still valid
up to , providing support to the hierarchical scenario for which massive
and bright systems are expected to be more clustered. The possibility of using
the measured 3PCF to provide independent constraints on the linear galaxy bias
has also been explored, showing promising results in agreement with other
probes.Comment: 12 pages, 11 figures, 2 tables, accepted for publication in A&
Multiwavelength dissection of a massive heavily dust-obscured galaxy and its blue companion at z∼2
Aims. We study a system of two galaxies, Astarte and Adonis, at z ∼ 2. At this time, the Universe was undergoing the peak of its star formation activity. Astarte is a dusty star-forming galaxy at the massive end of the main sequence (MS), and Adonis is a less massive companion galaxy that is bright in the ultraviolet and has an optical spectroscopic redshift. We investigate whether this ultramassive galaxy is quenching, and whether it has always been on the MS of star-forming galaxies.
Methods. We used the code CIGALE to model the spectral energy distribution. The code relies on the energetic balance between the ultraviolet and the infrared. We derived some of the key physical properties of Astarte and Adonis, mainly their star formation rates (SFRs), stellar masses, and dust luminosities. We inspected the variation of the physical parameters depending on the assumed dust-attenuation law. We also estimated the molecular gas mass of Astarte from its CO emission, using different αCO and transition ratios (r31), and we discuss the implication of the various assumptions on the gas-mass derivation.
Results. We find that Astarte exhibits a MS-like star formation activity, and Adonis is undergoing a strong starburst phase. The molecular gas mass of Astarte is far lower than the gas fraction of typical star-forming galaxies at z = 2. This low gas content and high SFR result in a depletion time of 0.22 ± 0.07 Gyr, which is slightly shorter than expected for a MS galaxy at this redshift. The CO luminosity relative to the total infrared luminosity suggests a MS-like activity when we assume a galactic conversion factor and a low transition ratio. The SFR of Astarte is on the same order when different attenuation laws are used, unlike its stellar mass, which increases when shallow attenuation laws are used (∼1 × 1011 M⊙ assuming a Calzetti relation, versus ∼4 × 1011 M⊙ assuming a shallow attenuation law). We discuss these properties and suggest that Astarte might be experiencing a recent decrease in star formation activity and is quenching through the MS following a starburst epoch
The VIMOS Public Extragalactic Redshift Survey (VIPERS): PCA-based automatic cleaning and reconstruction of survey spectra
Identifying spurious reduction artefacts in galaxy spectra is a challenge for
large surveys. We present an algorithm for identifying and repairing residual
spurious features in sky-subtracted galaxy spectra with application to the
VIPERS survey. The algorithm uses principal component analysis (PCA) applied to
the galaxy spectra in the observed frame to identify sky line residuals
imprinted at characteristic wavelengths. We further model the galaxy spectra in
the rest-frame using PCA to estimate the most probable continuum in the
corrupted spectral regions, which are then repaired. We apply the method to
90,000 spectra from the VIPERS survey and compare the results with a subset
where careful editing was performed by hand. We find that the automatic
technique does an extremely good job in reproducing the time-consuming manual
cleaning and does it in a uniform and objective manner across a large data
sample. The mask data products produced in this work are released together with
the VIPERS second public data release (PDR-2).Comment: Find the VIPERS data release at http://vipers.inaf.i
The VIMOS Public Extragalactic Redshift Survey (VIPERS): On the correct recovery of the count-in-cell probability distribution function
We compare three methods to measure the count-in-cell probability density
function of galaxies in a spectroscopic redshift survey. From this comparison
we found that when the sampling is low (the average number of object per cell
is around unity) it is necessary to use a parametric method to model the galaxy
distribution. We used a set of mock catalogues of VIPERS, in order to verify if
we were able to reconstruct the cell-count probability distribution once the
observational strategy is applied. We find that in the simulated catalogues,
the probability distribution of galaxies is better represented by a Gamma
expansion than a Skewed Log-Normal. Finally, we correct the cell-count
probability distribution function from the angular selection effect of the
VIMOS instrument and study the redshift and absolute magnitude dependency of
the underlying galaxy density function in VIPERS from redshift to .
We found very weak evolution of the probability density distribution function
and that it is well approximated, independently from the chosen tracers, by a
Gamma distribution.Comment: 14 pages, 11 figures, 2 table
The VIMOS Public Extragalactic Redshift Survey (VIPERS): A quiescent formation of massive red-sequence galaxies over the past 9 Gyr
We explore the evolution of the Colour-Magnitude Relation (CMR) and
Luminosity Function (LF) at 0.4<z<1.3 from the VIMOS Public Extragalactic
Redshift Survey (VIPERS) using ~45,000 galaxies with precise spectroscopic
redshifts down to i'_AB<22.5 over ~10.32 deg^2 in two fields. From z=0.5 to
z=1.3 the LF and CMR are well defined for different galaxy populations and
M^*_B evolves by ~1.04(1.09)+/-0.06(0.10) mag for the total (red) galaxy
sample. We compare different criteria for selecting early-type galaxies (ETGs):
(1) fixed cut in rest-frame (U-V) colours, (2) evolving cut in (U-V) colours,
(3) rest-frame (NUV-r')-(r'-K) colour selection, and (4) SED classification.
Regardless of the method we measure a consistent evolution of the red-sequence
(RS). Between 0.4<z<1.3 we find a moderate evolution of the RS intercept of
Delta(U-V)=0.28+/-0.14 mag, favouring exponentially declining star formation
(SF) histories with SF truncation at 1.7<=z<=2.3. Together with the rise in the
ETG number density by 0.64 dex since z=1, this suggests a rapid build-up of
massive galaxies (M>10^11 M_sun) and expeditious RS formation over a short
period of ~1.5 Gyr starting before z=1. This is supported by the detection of
ongoing SF in ETGs at 0.9<z<1.0, in contrast with the quiescent red stellar
populations of ETGs at 0.5<z<0.6. There is an increase in the observed CMR
scatter with redshift, two times larger than in galaxy clusters and at variance
with theoretical models. We discuss possible physical mechanisms that support
the observed evolution of the red galaxy population. Our findings point out
that massive galaxies have experienced a sharp SF quenching at z~1 with only
limited additional merging. In contrast, less-massive galaxies experience a mix
of SF truncation and minor mergers which build-up the low- and
intermediate-mass end of the CMR.Comment: 27 pages, 21 figures, accepted for publication in A&
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