221 research outputs found
Updated theoretical Period-Age and Period-Age-Color relations for Galactic Classical Cepheids: an application to the Gaia DR2 sample
Updated evolutionary and pulsational model predictions are combined in order
to interpret the properties of Galactic Classical Cepheids in the Gaia Data
Release 2. In particular, the location of the instability strip boundaries and
the analytical relations connecting pulsation periods to the intrinsic stellar
parameters are combined with evolutionary tracks to derive reliable and
accurate period-age, and the first theoretical period-age-color relations in
the Gaia bands for a solar chemical abundance pattern (=, =).
The adopted theoretical framework takes into account possible variations in the
mass-luminosity relation for the core helium-burning stage as due to changes in
the core convective overshooting and/or mass loss efficiency, as well as the
impact on the instability strip boundaries due to different assumptions for
superadiabatic convection efficiency. The inferred period-age and
period-age-color relations are applied to a selected sample of both fundamental
and first overtone Gaia Cepheids, and individual ages for the various adopted
theoretical scenarios are derived. The retrieved age distributions confirm that
a variation in the efficiency of superadiabatic convection in the pulsational
model computations has a negligible effect, whereas a brighter Mass-Luminosity
relation, as produced by mild overshooting, rotation or mass loss, implies
significantly older age predictions. Moreover, older Cepheids are found at
larger Galactocentric distances, while first overtone Cepheids are found to be
systematically older than the fundamental ones. The comparison with independent
age distribution analysis in literature supports the predictive capability of
current theoretical framework.Comment: 14 pages, 11 figures, 8 tables, accepted for publication in MNRA
Chapter Mapping of the risk of coastal erosion for two case studies: Pianosa island (Tuscany) and Piscinas (Sardinia)
This study focuses on the use of remote sensing to generate coastal erosion risk maps for Pianosa Island (Tuscany) and Piscinas dune system (Sardinia). The method made use of both ancillary and satellite data (Sentinel-2), in addition to SAR images (COSMO SkyMed and Sentinel-1B). TOA radiance products were atmospherically corrected and processed using Sen2Coral and BOMBER in order to map different marine substrates and bathymetry. The coastal erosion risk maps have been generated based on these output and the results confirm that the coasts of these sites don’t have coastal erosion problems
Effects of treatment for acromegaly on Bone Mineral Density (BMD): is Pegvisomant protective on lumbar BMD?
The abstract deals with the different effects of treatments for acromegaly on bon
The Physician's Gender Influences the Results of the Diagnostic Workup for Erectile Dysfunction
Impact of segmentation and discretization on radiomic features in 68Ga-DOTA-TOC PET/CT images of neuroendocrine tumor
OBJECTIVE: To identify the impact of segmentation methods and intensity discretization on radiomic features (RFs) extraction from 68Ga-DOTA-TOC PET images in patients with neuroendocrine tumors.METHODS: Forty-nine patients were retrospectively analyzed. Tumor contouring was performed manually by four different operators and with a semi-automatic edge-based segmentation (SAEB) algorithm. Three SUVmax fixed thresholds (20, 30, 40%) were applied. Fifty-one RFs were extracted applying two different intensity rescale factors for gray-level discretization: one absolute (AR60 = SUV from 0 to 60) and one relative (RR = min-max of the VOI SUV). Dice similarity coefficient (DSC) was calculated to quantify segmentation agreement between different segmentation methods. The impact of segmentation and discretization on RFs was assessed by intra-class correlation coefficients (ICC) and the coefficient of variance (COVL). The RFs' correlation with volume and SUVmax was analyzed by calculating Pearson's correlation coefficients.RESULTS: DSC mean value was 0.75 ± 0.11 (0.45-0.92) between SAEB and operators and 0.78 ± 0.09 (0.36-0.97), among the four manual segmentations. The study showed high robustness (ICC >0.9): (a) in 64.7% of RFs for segmentation methods using AR60, improved by applying SUVmax threshold of 40% (86.5%); (b) in 50.9% of RFs for different SUVmax thresholds using AR60; and (c) in 37% of RFs for discretization settings using different segmentation methods. Several RFs were not correlated with volume and SUVmax.CONCLUSIONS: RFs robustness to manual segmentation resulted higher in NET 68Ga-DOTA-TOC images compared to 18F-FDG PET/CT images. Forty percent SUVmax thresholds yield superior RFs stability among operators, however leading to a possible loss of biological information. SAEB segmentation appears to be an optimal alternative to manual segmentation, but further validations are needed. Finally, discretization settings highly impacted on RFs robustness and should always be stated
Period-Age-Metallicity and Period-Age-Color-Metallicity relations for Classical Cepheids: an application to the Gaia EDR3 sample
Based on updated pulsation models for Classical Cepheids, computed for
various assumptions about the metallicity and helium abundance, roughly
representative of pulsators in the Small Magellanic Cloud (= and
=), Large Magellanic Cloud (= and =), and M31
(= and =), and self-consistent updated evolutionary
predictions, we derived Period-Age and multi-band Period-Age-Color relations
that also take into account variations in the Mass-Luminosity relation. These
results, combined with those previously derived for Galactic Cepheids, were
used to investigate the metallicity effect when using these variables as age
indicators. In particular, we found that a variation in the metal abundance
affects both the slope and the zero point of the above-mentioned relations. The
new relations were applied to a sample of Gaia Early Data Release 3 Classical
Cepheids. The retrieved distribution of the individual ages confirms that a
brighter Mass-Luminosity relation produces older ages and that First Overtone
pulsators are found to be concentrated towards older ages with respect to the
Fundamental ones at a fixed Mass-Luminosity relation. Moreover, the inclusion
of a metallicity term in the Period-Age and Period-Age-Color relations slightly
modifies the predicted ages. In particular, the age distribution of the
selected sample of Galactic Cepheids is found to be shifted towards slightly
older values, when the F-mode canonical relations are considered, with respect
to the case at a fixed solar chemical composition. A marginally opposite
dependence can be found in the noncanonical F-mode and canonical FO-mode cases
Whole-Genome Sequencing Characterization of Virulence Profiles of Listeria monocytogenes Food and Human Isolates and In Vitro Adhesion/Invasion Assessment
none13sìListeria monocytogenes (Lm) is the causative agent of human listeriosis. Lm strains have
different virulence potential. For this reason, we preliminarily characterised via Whole-Genome
Sequencing (WGS) some Lm strains for their key genomic features and virulence-associated determinants,
assigning the clonal complex (CC). Moreover, the ability of the same strains to adhere to and
invade human colon carcinoma cell line Caco-2, evaluating the possible correspondence with their
genetic virulence profile, was also assessed. The clinical strains typed belonged to clonal complex
(CC)1, CC31, and CC101 and showed a very low invasiveness. The Lm strains isolated from food
were assigned to CC1, CC7, CC9, and CC121. All CC1 carried the hypervirulence pathogenicity
island LIPI-3 in addition to LIPI-1. Premature stop codons in the inlA gene were found only in Lm of
food origin belonging to CC9 and CC121. The presence of LIPI2_inlII was observed in all the CCs
except CC1. The CC7 strain, belonging to an epidemic cluster, also carried the internalin genes inlG
and inlL and showed the highest level of invasion. In contrast, the human CC31 strain lacked the
lapB and vip genes and presented the lowest level of invasiveness. In Lm, the genetic determinants
of hypo- or hypervirulence are not necessarily predictive of a cell adhesion and/or invasion ability
in vitro. Moreover, since listeriosis results from the interplay between host and virulence features of
the pathogen, even hypovirulent clones are able to cause infection in immunocompromised people.openGiuditta Fiorella Schiavano * , Collins Njie Ateba , Annalisa Petruzzelli , Veronica Mele ,
Giulia Amagliani , Fabrizia Guidi , Mauro De Santi , Francesco Pomilio , Giuliana Blasi ,
Antonietta Gattuso , Stefania Di Lullo , Elena Rocchegiani, Giorgio BrandiSchiavano, GIUDITTA FIORELLA; Njie Ateba, Collins; Petruzzelli, Annalisa; Mele, Veronica; Amagliani, Giulia; Guidi, Fabrizia; DE SANTI, Mauro; Pomilio, Francesco; Blasi, Giuliana; Gattuso, Antonietta; Di Lullo, Stefania; Rocchegiani, Elena; Brandi, Giorgi
Engagement of CD99 activates distinct programs in Ewing sarcoma and macrophages
Ewing sarcoma (EWS) is the second most common pediatric bone tumor. The EWS tumor microenvironment is largely recognized as immune-cold, with macrophages being the most abundant immune cells and their presence associated with worse patient prognosis. Expression of CD99 is a hallmark of EWS cells, and its targeting induces inhibition of EWS tumor growth through a poorly understood mechanism. In this study, we analyzed CD99 expression and functions on macrophages and investigated whether the concomitant targeting of CD99 on both tumor and macrophages could explain the inhibitory effect of this approach against EWS. Targeting CD99 on EWS cells downregulated expression of the "don't eat-me" CD47 molecule but increased levels of the "eat-me" phosphatidyl serine and calreticulin molecules on the outer leaflet of the tumor cell membrane, triggering phagocytosis and digestion of EWS cells by macrophages. In addition, CD99 ligation induced reprogramming of undifferentiated M0 macrophages and M2-like macrophages toward the inflammatory M1-like phenotype. These events resulted in the inhibition of EWS tumor growth. Thus, this study reveals what we believe to be a previously unrecognized function of CD99, which engenders a virtuous circle that delivers intrinsic cell death signals to EWS cells, favors tumor cell phagocytosis by macrophages, and promotes the expression of various molecules and cytokines, which are pro-inflammatory and usually associated with tumor regression. This raises the possibility that CD99 may be involved in boosting the antitumor activity of macrophages
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