122 research outputs found
A dynamically cold disk galaxy in the early Universe
The extreme astrophysical processes and conditions that characterize the
early Universe are expected to result in young galaxies that are dynamically
different from those observed today. This is because the strong effects
associated with galaxy mergers and supernova explosions would lead to most
young star-forming galaxies being dynamically hot, chaotic and strongly
unstable. Here we report the presence of a dynamically cold, but highly
star-forming, rotating disk in a galaxy at redshift () 4.2, when the
Universe was just 1.4 billion years old. Galaxy SPT-S J041839-4751.9 is
strongly gravitationally lensed by a foreground galaxy at , and it
is a typical dusty starburst, with global star-forming and dust properties that
are in agreement with current numerical simulations and observations of its
galaxy population. Interferometric imaging at a spatial resolution of about 60
pc reveals a ratio of rotational-to-random motions of ,
which is at least four times larger than expected from any galaxy evolution
model at this epoch, but similar to the ratios of spiral galaxies in the local
Universe. We derive a rotation curve with the typical shape of nearby massive
spiral galaxies, which demonstrates that at least some young galaxies are
dynamically akin to those observed in the local Universe, and only weakly
affected by extreme physical processes.Comment: Published in Nature on 12 August 2020. The published version is
available at http://www.nature.com/articles/s41586-020-2572-
Detecting low-mass haloes with strong gravitational lensing I: the effect of data quality and lensing configuration
This paper aims to quantify how the lowest halo mass that can be detected with galaxy-galaxy strong gravitational lensing depends on the quality of the observations and the characteristics of the observed lens systems. Using simulated data, we measure the lowest detectable NFW mass at each location of the lens plane, in the form of detailed sensitivity maps. In summary, we find that: (i) the lowest detectable mass Mlow decreases linearly as the signal-to-noise ratio (SNR) increases and the sensitive area is larger when we decrease the noise; (ii) a moderate increase in angular resolution (0.07′′ versus 0.09′′) and pixel scale (0.01′′ versus 0.04′′) improves the sensitivity by on average 0.25 dex in halo mass, with more significant improvement around the most sensitive regions; (iii) the sensitivity to low-mass objects is largest for bright and complex lensed galaxies located inside the caustic curves and lensed into larger Einstein rings (i.e rE ≥ 1.0′′). We find that for the sensitive mock images considered in this work, the minimum mass that we can detect at the redshift of the lens lies between 1.5 × 108 and 3 × 109 M☉. We derive analytic relations between Mlow, the SNR and resolution and discuss the impact of the lensing configuration and source structure. Our results start to fill the gap between approximate predictions and real data and demonstrate the challenging nature of calculating precise forecasts for gravitational imaging. In light of our findings, we discuss possible strategies for designing strong lensing surveys and the prospects for HST, Keck, ALMA, Euclid and other future observations
A three-day forest-bathing retreat enhances positive affect, vitality, optimism, and gratitude: An option for green-care tourism in Italy?
Forest-bathing experiences can be seen as guided recreational activities led by non-clinical trained practitioners in the context of green, slow, and mindful tourism. Notwithstanding its growing practice, there is a lack of research on the psychological benefits which can help support nature-based tourism destination managers in unlocking the potential of this emerging tourism demand. This study will fill in this gap by testing the hypothesis that a three-day forest-bathing retreat, which fits with the most common type of holidays in Europe, will enhance positive affect, vitality, optimism, and gratitude as indicators of hedonic and eudaimonic well-being. Forty-four adults were involved in the residential program and filled-in self-report questionnaires before and after the experience to assess the well-being dimensions considered. Results showed a significant increase for all the assessed variables. We conclude that forest bathing as a mindful tourism practice carried out in natural settings dominated by forests can favor hedonic and eudaimonic well-being, thus becoming a potential source of attractiveness for nature-based touristic destinations, but more transdisciplinary efforts are needed to exploit this potential. In particular, research gaps still exist in Europe on cause-effect relations between forest features and psychological benefits, how forests could be managed to guarantee these benefits to the advantage of a tourism destination, and how tourism and forest management sectors could collaborate in this direction
Subclinical liver fibrosis in patients with idiopathic 1 pulmonary fibrosis.
Background - Data on the presence of subclinical fibrosis across multiple organs in patients with idiopathic lung fibrosis (IPF) are lacking. Our study aimed at investigating through hepatic transient elastography (HTE) the prevalence and clinical impact of subclinical liver fibrosis in a cohort of patients with IPF.
Methods - Patients referred to the Centre for Rare Lung Disease of the University Hospital of Modena (Italy) from March 2012 to February 2013with established diagnosis of IPF and without a documented history of liver diseases were consecutively enrolled and underwent HTE. Based on hepatic stiffness status as assessed through METAVIR score patients were categorized as \u201c with liver fibrosis \u201d (corresponding to a METAVIR score of F1-F4) and \u201c without liver fibrosis\u201d (METAVIR F0). Potential predictors of liver fibrosis were investigated through logistic regression
model among clinical and serological variables. The overall survival (OS) was assessed according to liver fibrosis and multivariate Cox regression analysis was used to identify independent predictors.
Results - In 13 out of 37 patients (35%) with IPF a certain degree of liver fibrosis was documented.No correlation was found between liver stiffness and clinical-functional parameters. OS was lower in patients \u2018 with liver fibrosis\u2019 than in patients \u2018 without liver fibrosis\u2019 (median months 33[23-55] vs. 63[26-94], p=0.038). Patients \u2018 with liver fibrosis\u2019 presented a higher risk of death at seven years as compared to patients \u2018without liver fibrosis\u2019 (HR=2.6, 95%CI[1.003\u20136.7],p= 0.049). Higher level of AST to platelet ratio Index (APRI)was an independent predictor of survival (HR=4.52
95%CI[1.3\u201315.6], p=0.02).
Conclusions - In our cohort, more than one third of IPF patients had concomitant subclinical liver fibrosis that negatively affected OS. These preliminary claims further investigation aimed at clarifying the mechanisms beyond multiorgan fibrosis and its clinical implication in patients with IPF
The rocky road to quiescence: compaction and quenching of quasar host galaxies at z ∼ 2
We resolve the host galaxies of seven gravitationally lensed quasars at
redshift 1.5 to 2.8 using observations with the Atacama Large (sub-)Millimetre
Array. Using a visibility-plane lens modelling technique, we create pixellated
reconstructions of the dust morphology, and CO line morphology and kinematics.
We find that the quasar hosts in our sample can be distinguished into two
types: 1) galaxies characterised by clumpy, extended dust distributions
( kpc) and mean star formation rate surface densities
comparable to sub-mm-selected dusty star-forming galaxies ( M yr kpc); 2) galaxies that have sizes in
dust emission similar to coeval passive galaxies and compact starbursts
( kpc), with high mean star formation rate surface
densities ( 4004500 M yr kpc)
that may be Eddington-limited or super-Eddington. The small size of some quasar
hosts suggests that we observe them at a stage in their transformation into
compact spheroids, where a high density of dynamically unstable gas leads to
efficient star formation and black hole accretion. For the one system where we
probe the mass of the gas reservoir, we find a gas fraction of just and a depletion timescale of Myr, suggesting it is
transitioning into quiescence. In general, we expect that the extreme level of
star formation in the compact quasar host galaxies will rapidly exhaust their
gas reservoirs and could quench with or without help from active galactic
nuclei feedback.Comment: Accepted by MNRAS; 22 page
A microRNA prognostic signature in patients with diffuse intrinsic pontine gliomas through non-invasive liquid biopsy
Diffuse midline gliomas (DMGs) originate in the thalamus, brainstem, cerebellum and spine. This entity includes tumors that infiltrate the pons, called diffuse intrinsic pontine gliomas (DIPGs), with a rapid onset and devastating neurological symptoms. Since surgical removal in DIPGs is not feasible, the purpose of this study was to profile circulating miRNA expression in DIPG patients in an effort to identify a non-invasive prognostic signature with clinical impact. Using a high-throughput platform, miRNA expression was profiled in serum samples collected at the time of MRI diagnosis and prior to radiation and/or systemic therapy from 47 patients enrolled in clinical studies, combining nimotuzumab and vinorelbine with concomitant radiation. With progression-free survival as the primary endpoint, a semi-supervised learning approach was used to identify a signature that was also tested taking overall survival as the clinical endpoint. A signature comprising 13 circulating miRNAs was identified in the training set (n = 23) as being able to stratify patients by risk of disease progression (log-rank p = 0.00014; HR = 7.99, 95% CI 2.38–26.87). When challenged in a separate validation set (n = 24), it confirmed its ability to predict progression (log-rank p = 0.00026; HR = 5.51, 95% CI 2.03–14.9). The value of our signature was also confirmed when overall survival was considered (log-rank p = 0.0021, HR = 4.12, 95% CI 1.57–10.8). We have identified and validated a prognostic marker based on the expression of 13 circulating miRNAs that can shed light on a patient’s risk of progression. This is the first demonstration of the usefulness of nucleic acids circulating in the blood as powerful, easy-to-assay molecular markers of disease status in DIPG. This study provides Class II evidence that a signature based on 13 circulating miRNAs is associated with the risk of disease progression
Missing Dark Matter in the Local Universe
A sample of 11 thousand galaxies with radial velocities V_ LG < 3500 km/s is
used to study the features of the local distribution of luminous (stellar) and
dark matter within a sphere of radius of around 50 Mpc around us. The average
density of matter in this volume, Omega_m,loc=0.08+-0.02, turns out to be much
lower than the global cosmic density Omega_m,glob=0.28+-0.03. We discuss three
possible explanations of this paradox: 1) galaxy groups and clusters are
surrounded by extended dark halos, the major part of the mass of which is
located outside their virial radii; 2) the considered local volume of the
Universe is not representative, being situated inside a giant void; and 3) the
bulk of matter in the Universe is not related to clusters and groups, but is
rather distributed between them in the form of massive dark clumps. Some
arguments in favor of the latter assumption are presented. Besides the two
well-known inconsistencies of modern cosmological models with the observational
data: the problem of missing satellites of normal galaxies and the problem of
missing baryons, there arises another one - the issue of missing dark matter.Comment: 19 pages, 7 figures, 1 table (accepted
Three QSOs acting as strong gravitational lenses
We report the discovery of three new cases of QSOs acting as strong
gravitational lenses on background emission line galaxies: SDSS J0827+5224
(zQSO = 0.293, zs = 0.412), SDSS J0919+2720 (zQSO = 0.209, zs = 0.558), SDSS
J1005+4016 (zQSO = 0.230, zs = 0.441). The selection was carried out using a
sample of 22,298 SDSS spectra displaying at least four emission lines at a
redshift beyond that of the foreground QSO. The lensing nature is confirmed
from Keck imaging and spectroscopy, as well as from HST/WFC3 imaging in the
F475W and F814W filters. Two of the QSOs have face-on spiral host galaxies and
the third is a QSO+galaxy pair. The velocity dispersion of the host galaxies,
inferred from simple lens modeling, is between \sigma_v = 210 and 285 km/s,
making these host galaxies comparable in mass with the SLACS sample of
early-type strong lenses.Comment: 9 pages, 8 figures, accepted for publication in A&
Time Delay Lens Modelling Challenge
In recent years, breakthroughs in methods and data have enabled gravitational
time delays to emerge as a very powerful tool to measure the Hubble constant
. However, published state-of-the-art analyses require of order 1 year of
expert investigator time and up to a million hours of computing time per
system. Furthermore, as precision improves, it is crucial to identify and
mitigate systematic uncertainties. With this time delay lens modelling
challenge we aim to assess the level of precision and accuracy of the modelling
techniques that are currently fast enough to handle of order 50 lenses, via the
blind analysis of simulated datasets. The results in Rung 1 and Rung 2 show
that methods that use only the point source positions tend to have lower
precision () while remaining accurate. In Rung 2, the methods that
exploit the full information of the imaging and kinematic datasets can recover
within the target accuracy () and precision ( per
system), even in the presence of poorly known point spread function and complex
source morphology. A post-unblinding analysis of Rung 3 showed the numerical
precision of the ray-traced cosmological simulations to be insufficient to test
lens modelling methodology at the percent level, making the results difficult
to interpret. A new challenge with improved simulations is needed to make
further progress in the investigation of systematic uncertainties. For
completeness, we present the Rung 3 results in an appendix, and use them to
discuss various approaches to mitigating against similar subtle data generation
effects in future blind challenges.Comment: 23 pages, 12 figures, 6 tables, MNRAS accepte
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