103 research outputs found
One special question to start with: can HIF/NFkB be a target in inflammation?
Hypoxia and Inflammation are strictly interconnected with important consequences at clinical and therapeutic level. While cell and tissue damage due to acute hypoxia mostly leads to cell necrosis, in chronic hypoxia, cells that are located closer to vessels are able to survive adapting their phenotype through the expression of a number of genes, including proinflammatory receptors for alarmins. These receptors are activated by alarmins released by necrotic cells and generate signals for master transcription factors such as NFkB, AP1, etc. which control hundreds of genes for innate immunity and damage repair. Clinical consequences of chronic inflammatory reparative response activation include cell and tissue remodeling, damage in the primary site and, the systemic involvement of distant organs and tissues. Thus every time a tissue environment becomes stably hypoxic, inflammation can be activated followed by chronic damage and cell death or repair with vessel proliferation and fibrosis. This pathway can occur in cancer, myocardial infarction and stroke, diabetes, obesity, neurodegenerative diseases, chronic and autoimmune diseases and age-related diseases. Interestingly, proinflammatory gene expression can be observed earlier in hypoxic tissue cells and, in addition, in activated resident or recruited leukocytes. Herewith, the reciprocal relationships between hypoxia and inflammation will be shortly reviewed to underline the possible therapeutic targets to control hypoxia-related inflammation in a number of epidemiologically important human diseases and conditions
Specific star-formation and the relation to stellar mass from 0<z<2 as seen in the far-infrared at 70 and 160mu
We use the Spitzer Wide-area InfraRed Extragalactic Legacy Survey (SWIRE) to
explore the specific star-formation activity of galaxies and their evolution
near the peak of the cosmic far-infrared (FIR) background at 70 and 160um. We
use a stacking analysis to determine the mean FIR properties of well defined
subsets of galaxies at flux levels well below the FIR catalogue detection
limits of SWIRE and other Spitzer surveys. We tabulate the contribution of
different subsets of galaxies to the FIR background at 70um and 160um. These
long wavelengths provide a good constraint on the bolometric, obscured
emission. The large area provides good constraints at low z and in finer
redshift bins than previous work. At all redshifts we find that the specific
FIR Luminosity (sLFIR) decreases with increasing mass, following a trend
L_FIR/M* propto M_* ^beta with beta =-0.38\pm0.14. This is a more continuous
change than expected from the {Delucia2007} semi-analytic model suggesting
modifications to the feedback prescriptions. We see an increase in the sLFIR by
about a factor of ~100 from 0<z<2 and find that the sLFIR evolves as
(1+z)^alpha with alpha=4.4\pm0.3 for galaxies with 10.5 < log M*/Msun < 12.
This is considerably steeper than the {Delucia2007} semi-analytic model (alpha
\sim 2.5). When separating galaxies into early and late types on the basis of
the optical/IR spectral energy distributions we find that the decrease in sLFIR
with stellar mass is stronger in early type galaxies (beta ~ -0.46), while late
type galaxies exhibit a flatter trend (beta \sim -0.15). The evolution is
strong for both classes but stronger for the early type galaxies. The early
types show a trend of decreasing strength of evolution as we move from lower to
higher masses while the evolution of the late type galaxies has little
dependence on stellar mass. We suggest that in late-type galaxies we are seeing
a consistently declining sSFR..Comment: v2 Update doesn't change the content of the paper, but now includes
data files for the plots Fig 5-13 (all.plotdat, spi.plotdat and ell.plotdat
on arXiv package
The evolution of the rest-frame J- and H-band luminosity function of galaxies to z=3.5
We present the rest-frame J- and H-band luminosity function (LF) of field
galaxies, based on a deep multi-wavelength composite sample from the MUSYC,
FIRES and FIREWORKS survey public catalogues, covering a total area of 450
arcmin^2. The availability of flux measurements in the Spitzer IRAC 3.6, 4.5,
5.8, and 8 um channels allows us to compute absolute magnitudes in the
rest-frame J and H bands up to z=3.5 minimizing the dependence on the stellar
evolution models. We compute the LF in the four redshift bins 1.5<z<2.0,
2.0<z<2.5, 2.5<z<3.0 and 3.0<z<3.5. Combining our results with those already
available at lower redshifts, we find that (1) the faint end slope is
consistent with being constant up to z=3.5, with alpha=-1.05+/-0.03 for the
rest-frame J band and alpha=-1.15+/-0.02 for the rest-frame H band; (2) the
normalization phi* decreases by a factor of 6 between z=0 and z~1.75 and by a
factor 3 between z~1.75 and z=3.25; (3) the characteristic magnitude M* shows a
brightening from z=0 to z~2 followed by a slow dimming to z=3.25. We finally
compute the luminosity density (LD) in both rest-frame J and H bands. The
analysis of our results together with those available in the literature shows
that the LD is approximately constant up to z~1, and it then decreases by a
factor of 6 up to z=3.5.Comment: 14 pages, 12 figures. MNRAS accepte
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&
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
Detailed modelling of a large sample of Herschel sources in the Lockman Hole: identification of cold dust and of lensing candidates through their anomalous SEDs
We have studied in detail a sample of 967 SPIRE sources with 5σ detections at 350 and 500 μm and associations with Spitzer-SWIRE 24 μm galaxies in the HerMES-Lockman survey area, fitting theirmid- and far-infrared, and submillimetre, spectral energy distributions (SEDs) in an automatic search with a set of six infrared templates. For almost 300 galaxies,we havemodelled their SEDs individually to ensure the physicality of the fits. We confirm the need for the new cool and cold cirrus templates, and also of the young starburst template, introduced in earlier work. We also identify 109 lensing candidates via their anomalous SEDs and provide a set of colour–redshift constraints which allow lensing candidates to be identified from combined Herschel and Spitzer data. The picture that emerges of the submillimetre galaxy population is complex, comprising ultraluminous and hyperluminous starbursts, lower luminosity galaxies dominated by interstellar dust emission, lensed galaxies and galaxies with surprisingly cold (10–13 K) dust. 11 per cent of 500 μm selected sources are lensing candidates. 70 per cent of the unlensed sources are ultraluminous infrared galaxies and 26 per cent are hyperluminous. 34 per cent are dominated by optically thin interstellar dust (‘cirrus’) emission, but most of these are due to cooler dust than is characteristic of our Galaxy. At the highest infrared luminosities we see SEDs dominated by M82, Arp 220 and young starburst types, in roughly equal proportions
Unveiling the oldest and most massive galaxies at very high redshift
(Abridged) This work explores the existence of high redshift massive galaxies
unveiled with Spitzer+IRAC, but missed by conventional selection techniques
based on optical and near-infrared observations. To this end, we use the
multi-wavelength imaging data available for the GOODS-South field, and select a
flux-limited sample from the IRAC 3.6um image to m(AB)<23.26. We confine our
study to the galaxies undetected by the optical HST+ACS imaging and close to
the detection limit of the K-band image (K>23.5 AB). Our selection unveiled 20
galaxies on which we performed a detailed photometric analysis. For each
galaxy, we built an SED based on optical-to-8um photometry to estimate the
photo-z and to derive the main galaxies physical properties. The majority of
the sample sources show degenerate/bimodal solutions for the photometric
redshifts (Abridged). These can either be heavily dust-enshrouded (Av~2-4)
starbursts at 210^12 Lsun, or massive
post-starburst galaxies in the redshift interval 4<z<9 with stellar masses of
10^11 Msun. One galaxy, the only source in our sample with both an X-ray and a
24um detection, might be an extremely massive object at z~8 detected during a
post-starburst phase with concomitant QSO activity (although a lower-z solution
is not excluded). Our investigation of Spitzer-selected galaxies with very red
SEDs and completely undetected in the optical reveals a potential population of
massive galaxies at z>4 which appear to include significant AGN emissions.
These sources may be the oldest stellar systems at z~4. These, previously
unrecognized, optically obscured objects might provide an important
contribution to the massive-end (M>10^11 sun) of the high-z stellar mass
function and they would almost double it (Abridged).Comment: Accepted for publication in Astronomy and Astrophysic
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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