22 research outputs found
Gravitational waves HI intensity mapping: cosmological and astrophysical applications
Two of the most rapidly growing observables in cosmology and astrophysics are
gravitational waves (GW) and the neutral hydrogen (HI) distribution. In this
work, we investigate the cross-correlation between resolved gravitational wave
detections and HI signal from intensity mapping (IM) experiments. By using a
tomographic approach with angular power spectra, including all projection
effects, we explore possible applications of the combination of the Einstein
Telescope and the SKAO intensity mapping surveys. We focus on three main
topics: \textit{(i)} statistical inference of the observed redshift
distribution of GWs; \textit{(ii)} constraints on dynamical dark energy models
as an example of cosmological studies; \textit{(iii)} determination of the
nature of the progenitors of merging binary black holes, distinguishing between
primordial and astrophysical origin. Our results show that: \textit{(i)} the GW
redshift distribution can be calibrated with good accuracy at low redshifts,
without any assumptions on cosmology or astrophysics, potentially providing a
way to probe astrophysical and cosmological models; \textit{(ii)} the
constrains on the dynamical dark energy parameters are competitive with IM-only
experiments, in a complementary way and potentially with less systematics;
\textit{(iii)} it will be possible to detect a relatively small abundance of
primordial black holes within the gravitational waves from resolved mergers.
Our results extend towards the promising field of
multi-tracing cosmology and astrophysics, which has the major advantage of
allowing scientific investigations in ways that would not be possible by
looking at single observables separately.Comment: 36 pages, 7 figures, 1 tabl
Intensity and anisotropies of the stochastic Gravitational Wave background from merging compact binaries in galaxies
We investigate the isotropic and anisotropic components of the Stochastic
Gravitational Wave Background (SGWB) originated from unresolved merging compact
binaries in galaxies. We base our analysis on an empirical approach to galactic
astrophysics that allows to follow the evolution of individual systems. We then
characterize the energy density of the SGWB as a tracer of the total matter
density, in order to compute the angular power spectrum of anisotropies with
the Cosmic Linear Anisotropy Solving System (CLASS) public code in full
generality. We obtain predictions for the isotropic energy density and for the
angular power spectrum of the SGWB anisotropies, and study the prospect for
their observations with advanced Laser Interferometer Gravitational-Wave and
Virgo Observatories and with the Einstein Telescope. We identify the
contributions coming from different type of sources (binary black holes, binary
neutron stars and black hole-neutron star) and from different redshifts. We
examine in detail the spectral shape of the energy density for all types of
sources, comparing the results for the two detectors. We find that the power
spectrum of the SGWB anisotropies behaves like a power law on large angular
scales and drops at small scales: we explain this behaviour in terms of the
redshift distribution of sources that contribute most to the signal, and of the
sensitivities of the two detectors. Finally, we simulate a high resolution full
sky map of the SGWB starting from the power spectra obtained with CLASS and
including Poisson statistics and clustering properties.Comment: 35 pages, 12 figure
Ultra-High recovery Multi-Effect Distillation for nearly-liquid discharge desalination
The availability of water is still one of the most important factors for the growth and sustainability of a country. Although many countries have free access to an inexhaustible source of water, the sea, this source cannot, as it is, be used for human purposes. To face this problem, desalination has been proposed for fresh water production, though the limitation in recovery of conventional RO plants and the generation of a waste brine effluent pose some issues of actual sustainability. Multiple Effect Distillation (MED) has been proposed in this work to be coupled with a NanoFiltration unit in order to dramatically enhance the conversion ratio of the process, thus reducing the brine volume produced.
A 2-effects MED pilot plant, with a capacity of about 1.5 m3/d, has been installed as part of the treatment chain of the Watermining project, within the premises of the power station of the island of Lampedusa (Sicily, Italy) and is fully powered by waste heat at 70-80°C from the diesel engines of the power station.
Several operating conditions were investigated using real saline stream produced as a permeate of the NF unit. A recovery ratio above 80% has been achieved and an effluent brine conductivity between 250 and 300 mS/cm was produced, which is close to the saturation in NaCl, thus being excellent for being sent into evaporative ponds. A temperature between 40°C and 55°C has been maintained in the evaporator, suitable for integration with very low temperature waste heat sources. In all cases the distillate productivity and the conductivity of the produced water were maintained close the nominal values, with the latter typically ranging between 10 and 20 μs/cm
Polycomb proteins control proliferation and transformation independently of cell cycle checkpoints by regulating DNA replication
The ability of PRC1 and PRC2 to promote proliferation is a main feature that links polycomb (PcG) activity to cancer. PcGs silence the expression of the tumour suppressor locus Ink4a/Arf, whose products positively regulate pRb and p53 functions. Enhanced PcG activity is a frequent feature of human tumours, and PcG inhibition has been proposed as a strategy for cancer treatment. However, the recurrent inactivation of pRb/p53 responses in human cancers raises a question regarding the ability of PcG proteins to affect cellular proliferation independently from this checkpoint. Here we demonstrate that PRCs regulate cellular proliferation and transformation independently of the Ink4a/Arf-pRb-p53 pathway. We provide evidence that PRCs localize at replication forks, and that loss of their function directly affects the progression and symmetry of DNA replication forks. Thus, we have identified a novel activity by which PcGs can regulate cell proliferation independently of major cell cycle restriction checkpoints. \ua92014 Macmillan Publishers Limited. All rights reserved
Keeping the Centromere under Control: A Promising Role for DNA Methylation
International audienc
Polycomb Complex PRC1 Preserves Intestinal Stem Cell Identity by Sustaining Wnt/beta-Catenin Transcriptional Activity
Polycomb repressive complexes (PRCs) are among the most important gatekeepers of establishing and maintaining cell identity in metazoans. PRC1, which plays a dominant role in this context, executes its functions via multiple subcomplexes, which all contribute to H2AK119 mono-ubiquitination (H2Aubq). Despite our comprehensive knowledge of PRC1-dependent H2Aubq in embryonic stem cells and during early development, its role in adult stem cells still remains poorly characterized. Here we show that PRC1 activity is required for the integrity of the intestinal epithelium, regulating stem cell self-renewal via a cell-autonomous mechanism that is independent from Cdkn2a expression. By dissecting the PRC1-dependent transcription program in intestinal stem cells, we demonstrate that PRC1 represses a large number of non-lineage-specific transcription factors that directly affect beta-catenin/Tcf transcriptional activity. Our data reveal that PRC1 preserves Wnt/beta-catenin activity in adult stem cells to maintain intestinal homeostasis and supports tumor formation induced by the constitutive activation of this pathway
Phosphorylation of CENP-A on serine 7 does not control centromere function
International audienc
High angular resolution diffusion imaging in a child with autism spectrum disorder and comparison with his unaffected identical twin
In recent years, the use of brain diffusion MRI has led to the hypothesis that children with autism spectrum disorder (ASD) show abnormally connected brains. We used the model of disease-discordant identical twins to test the hypothesis that higher-order diffusion MRI protocols are able to detect abnormal connectivity in a single subject
CENP-A chromatin prevents replication stress at centromeres to avoid structural aneuploidy
Chromosome segregation relies on centromeres, yet their repetitive DNA is often prone to aberrant rearrangements under pathological conditions. Factors that maintain centromere integrity to prevent centromere-associated chromosome translocations are unknown. Here, we demonstrate the importance of the centromere-specific histone H3 variant CENP-A in safeguarding DNA replication of alpha-satellite repeats to prevent structural aneuploidy. Rapid removal of CENP-A in S phase, but not other cell-cycle stages, caused accumulation of R loops with increased centromeric transcripts, and interfered with replication fork progression. Replication without CENP-A causes recombination at alpha-satellites in an R loop-dependent manner, unfinished replication, and anaphase bridges. In turn, chromosome breakage and translocations arise specifically at centromeric regions. Our findings provide insights into how specialized centromeric chromatin maintains the integrity of transcribed noncoding repetitive DNA during S phase