10 research outputs found
Acute kidney injury and acute kidney disease in high-dose cisplatin-treated head and neck cancer
Background: In locally advanced head and neck squamous cell carcinoma (LA-SCCHN) at least 200mg/m2 (standard dose 300 mg/m2) of cisplatin concomitant with radiotherapy represents the standard of care, both in postoperative and conservative settings. Nevertheless, high dose administration every 3 weeks is often replaced with low dose weekly cisplatin to avoid toxicities like kidney injury, though often failing to reach the therapeutic dose. Our aim was to investigate the incidence of renal impairment in the real-life setting, integrating high dose cisplatin with adequate supportive therapy, and to explore both Acute Kidney Injury (AKI) and Acute Kidney Disease (AKD), a recently described clinical renal syndrome that encompasses functional alterations of the kidney lasting fewer than 3 months. Methods: One hundred and nine consecutive patients affected by LA-SCCHN and treated with at least a cumulative dosage of 200 mg/m2 of cisplatin concomitant with radiotherapy were enrolled in this prospective observational study. Results: AKI was reported in 12.8% of patients, 50% of whom were stage 1 (KDIGO criteria), while 25.7% of the cohort developed AKD. Patients with baseline estimated Glomerular Filtration Rate (eGFR) < 90 ml/min showed a higher incidence of AKD (36.2% vs 17.7%). Hypertension, baseline eGFR, and therapy with Renin-angiotensin-aldosterone system inhibitors proved to be significant factors associated with both AKI and AKD. Conclusion: AKI and AKD are not rare complications of high-dose cisplatin, but an appropriate prevention strategy and accurate monitoring of patients during treatment could lead to a reduction of the burden of these conditions
Looking into the faintEst WIth MUSE (LEWIS): on the nature of ultra-diffuse galaxies in the Hydra-I cluster.I. Project description and preliminary results
Looking into the faintEst WIth MUSE (LEWIS) is an ESO large observing
programme aimed at obtaining the first homogeneous integral-field spectroscopic
survey of 30 extremely low-surface brightness (LSB) galaxies in the Hydra I
cluster of galaxies, with MUSE at ESO-VLT. The majority of LSB galaxies in the
sample (22 in total) are ultra-diffuse galaxies (UDGs). The distribution of
systemic velocities Vsys ranges between 2317 km/s and 5198 km/s and is centred
on the mean velocity of Hydra I (Vsys = 3683 46 km/s). Considering the
mean velocity and the velocity dispersion of the cluster, 17 out of 20 targets
are confirmed cluster members. To assess the quality of the data and
demonstrate the feasibility of the science goals, we report the preliminary
results obtained for one of the sample galaxies, UDG11. For this target, we
derived the stellar kinematics, including the 2-dimensional maps of
line-of-sight velocity and velocity dispersion, constrained age and
metallicity, and studied the globular cluster (GC) population hosted by the
UDG. Results are compared with the available measurements for UDGs and dwarf
galaxies in literature. By fitting the stacked spectrum inside one effective
radius, we find that UDG11 has a velocity dispersion km/s,
it is old ( Gyr), metal-poor ([M/H]=-1.170.11 dex) and has a total
dynamical mass-to-light ratio M, comparable to those observed for
classical dwarf galaxies. The spatially resolved stellar kinematics maps
suggest that UDG11 does not show a significant velocity gradient along either
major or minor photometric axes. We find two GCs kinematically associated with
UDG11. The estimated total number of GCs in UDG11, corrected for the
spectroscopic completeness limit, is , which
corresponds to a GC specific frequency of .Comment: Accepted for publication in Astronomy and Astrophysic
Galaxy populations in the Hydra i cluster from the VEGAS survey:I. Optical properties of a large sample of dwarf galaxies
At ~50 Mpc, the Hydra I cluster of galaxies is among the closest cluster in
the z=0 Universe, and an ideal environment to study dwarf galaxy properties in
a cluster environment. We exploit deep imaging data of the Hydra I cluster to
construct a new photometric catalog of dwarf galaxies in the cluster core,
which is then used to derive properties of the Hydra I cluster dwarf galaxies
population as well as to compare with other clusters. Moreover, we investigate
the dependency of dwarf galaxy properties on their surrounding environment. The
new Hydra I dwarf catalog contains 317 galaxies with luminosity between
-18.5<<-11.5 mag, a semi-major axis larger than ~200 pc (a=0.84 arcsec),
of which 202 are new detections, previously unknown dwarf galaxies in the Hydra
I central region. We estimate that our detection efficiency reaches 50% at the
limiting magnitude =-11.5 mag, and at the mean effective surface
brightness =26.5 mag/. We present the standard
scaling relations for dwarf galaxies and compare them with other nearby
clusters. We find that there are no observational differences for dwarfs
scaling relations in clusters of different sizes. We study the spatial
distribution of galaxies, finding evidence for the presence of substructures
within half the virial radius. We also find that mid- and high-luminosity
dwarfs (<-14.5 mag) become on average redder toward the cluster center,
and that they have a mild increase in with increasing clustercentric
distance, similar to what is observed for the Fornax cluster. No clear
clustercentric trends are reported with surface brightness and S\'ersic index.
Considering galaxies in the same magnitude-bins, we find that for high and
mid-luminosity dwarfs (<-13.5 mag) the g-r color is redder for the
brighter surface brightness and higher S\'ersic n index objects.Comment: Accepted for publication in A&A. 25 pages, 21 figure
Development of SEM Metallography for the Study of the Mg-MgH2 Phase Transformation
The study of sorption reactions of metal hydrides is the subject of numerous researches in connection with the development of a safe technology for hydrogen storage, and MgH2, in particular, is one of the most promising materials. Several efforts have been already carried out in order to understand the kinetic mechanisms involved in the MgH2 decomposition which is at the basis of H2 release. However, the role of additives and induced structural defects on the sorption cycles is not clear yet. With the purpose of supporting the reaction analysis we have developed an experimental protocol for the metallographic examination at high spatial resolution of partially desorbed MgH2 powders. In particular, this procedure allows cross-sectional analysis of powders embedded into conductive matrix, while the observation method produces a different contrast among metallic Mg, MgH2 and additive particles made of heavier materials.Materials and Technology for Hydrogen Storage : November 26-30, 2007
Galaxy populations in the Hydra I cluster from the VEGAS survey:I. optical properties of a large sample of dwarf galaxies
Abstract
Context: Due to their relatively low stellar mass content and diffuse nature, the evolution of dwarf galaxies can be strongly affected by their environment. Analyzing the properties of the dwarf galaxies over a wide range of luminosities, sizes, morphological types, and environments, we can obtain insights about their evolution. At âŒ50 Mpc, the Hydra I cluster of galaxies is among the closest cluster in the zâââ0 Universe, and an ideal environment to study dwarf galaxy properties in a cluster environment.
Aims: We exploit deep imaging data of the Hydra I cluster to construct a new photometric catalog of dwarf galaxies in the cluster core, which is then used to derive properties of the Hydra I cluster dwarf galaxy population as well as to compare it with other clusters. Moreover, we investigate the dependency of dwarf galaxy properties on their surrounding environment.
Methods: The new wide-field g- and r-band images of the Hydra I cluster obtained with the OmegaCAM camera on the VLT Survey Telescope (VST) in the context of the VST Early-type GAlaxy Survey (VEGAS) were used to study the dwarf galaxy population in the Hydra I cluster core down to r-band magnitude Mrâ=ââ11.5 mag. We used an automatic detection tool to identify dwarf galaxies from a âŒ1 degÂČ field centered on the Hydra I core, covering almost half of the cluster virial radius. The photometric pipeline was used to estimate the principal photometric parameters for all targets. Scaling relations and visual inspection were used to assess the cluster membership and construct a new dwarf galaxy catalog. Finally, based on the new catalog, we studied the structural (SĂ©rsic index n, effective radius Re, and axis ratio) and photometric (colors and surface brightness) properties of the dwarf galaxies, also investigating how they vary as a function of clustercentric distance.
Results: The new Hydra I dwarf catalog contains 317 galaxies with a luminosity between â18.5â<âMrâ<ââ11.5 mag, a semi-major axis larger than âŒ200 pc (aâ=â0.84âł), of which 202 are new detections, and previously unknown dwarf galaxies in the Hydra I central region. We estimate that our detection efficiency reaches 50% at the limiting magnitude Mrâ=ââ11.5 mag, and at the mean effective surface brightness ÎŒÌe,râ=â26.5 mag arcsecâ2. We present the standard scaling relations for dwarf galaxies, which are color-magnitude, size-luminosity, and SĂ©rsic n-magnitude relations, and compare them with other nearby clusters. We find that there are no observational differences for dwarfs scaling relations in clusters of different sizes. We study the spatial distribution of galaxies, finding evidence for the presence of substructures within half the virial radius. We also find that mid- and high-luminosity dwarfs (Mrâ<ââ14.5 mag) become, on average, redder toward the cluster center, and that they have a mild increase in Re with increasing clustercentric distance, similar to what is observed for the Fornax cluster. No clear clustercentric trends are reported for surface brightness and SĂ©rsic index. Considering galaxies in the same magnitude bins, we find that for high and mid-luminosity dwarfs (Mrâ<ââ13.5 mag), the gâ
ââ
r color is redder for the brighter surface brightness and higher SĂ©rsic n index objects. This finding is consistent with the effects of harassment and/or partial gas stripping