207 research outputs found
Muons in the aftermath of neutron star mergers and their impact on trapped neutrinos
In the upcoming years, present and next-generation gravitational wave
observatories will detect a larger number of binary neutron star (BNS) mergers
with increasing accuracy. In this context, improving BNS merger numerical
simulations is crucial to correctly interpret the data and constrain the
equation of state (EOS) of neutron stars (NSs). State-of-the-art simulations of
BNS mergers do not include muons. However, muons are known to be relevant in
the microphysics of cold NSs and are expected to have a significant role in
mergers, where the typical thermodynamic conditions favour their production.
Our work is aimed at investigating the impact of muons on the merger remnant.
We post-process the outcome of four numerical relativity simulations of BNS
mergers performed with three different baryonic EOSs and two mass ratios
considering the first milliseconds after merger. We compute the abundance
of muons in the remnant and analyse how muons affect the trapped neutrino
component and the fluid pressure. We find that depending on the baryonic EOS,
the net fraction of muons is between and the net fraction of
electrons. Muons change the flavour hierarchy of trapped (anti-)neutrinos such
that deep inside the remnant, muon anti-neutrinos are the most abundant,
followed by electron anti-neutrinos. Finally, muons and trapped neutrinos
modify the neutron-to-proton ratio, affecting the remnant pressure by up to
when compared with calculations neglecting them. This work demonstrates
that muons have a non-negligible effect on the outcome of BNS merger
simulations, and they should be included to improve the accuracy of a
simulation.Comment: 19 pages, 11 figure
Anthocyanins are Key Regulators of Drought Stress Tolerance in Tobacco
Abiotic stresses will be one of the major challenges for worldwide food supply in the near future. Therefore, it is important to understand the physiological mechanisms that mediate plant responses to abiotic stresses. When subjected to UV, salinity or drought stress, plants accumulate specialized metabolites that are often correlated with their ability to cope with the stress. Among them, anthocyanins are the most studied intermediates of the phenylpropanoid pathway. However, their role in plant response to abiotic stresses is still under discussion. To better understand the effects of anthocyanins on plant physiology and morphogenesis, and their implications on drought stress tolerance, we used transgenic tobacco plants (AN1), which over-accumulated anthocyanins in all tissues. AN1 plants showed an altered phenotype in terms of leaf gas exchanges, leaf morphology, anatomy and metabolic profile, which conferred them with a higher drought tolerance compared to the wild-type plants. These results provide important insights for understanding the functional reason for anthocyanin accumulation in plants under stress
Numerical Relativity Simulations of the Neutron Star Merger GW170817: Long-Term Remnant Evolutions, Winds, Remnant Disks, and Nucleosynthesis
We present a systematic numerical-relativity study of the dynamical ejecta,
winds and nucleosynthesis in neutron star merger remnants. Binaries with the
chirp mass compatible with GW170817, different mass ratios, and five
microphysical equations of state (EOS) are simulated with an approximate
neutrino transport and a subgrid model for magnetohydrodynamics turbulence up
to 100 milliseconds postmerger. Spiral density waves propagating from the
neutron star remnant to the disk trigger a wind with mass flux
persisting for the entire simulation as long
as the remnant does not collapse to black hole. This wind has average electron
fraction and average velocity c and thus is a
site for the production of weak -process elements (mass number ).
Disks around long-lived remnants have masses ,
temperatures peaking at MeV near the inner edge, and a
characteristic double-peak distribution in entropy resulting from shocks
propagating through the disk. The dynamical and spiral-wave ejecta computed in
our targeted simulations are not compatible with those inferred from AT2017gfo
using two-components kilonova models. Rather, they indicate that
multi-component kilonova models including disk winds are necessary to interpret
AT2017gfo. The nucleosynthesis in the combined dynamical ejecta and spiral-wave
wind in the comparable-mass long-lived mergers robustly accounts for all the
-process peaks, from mass number to actinides in terms of solar
abundances. Total abundandes are weakly dependent on the EOS, while the mass
ratio affect the production of first peak elements.Comment: 20 pages, 13 figures, 3 table
Identification of low intratumoral gene expression heterogeneity in neuroblastic tumors by genome-wide expression analysis and Game Theory
BACKGROUND. Neuroblastic tumors (NTs) are largely comprised of neuroblastic (Nb) cells with various quantities of Schwannian stromal (SS) cells. NTs show a variable genetic heterogeneity. NT gene expression profiles reported so far have not taken into account the cellular components. The authors reported the genome-wide expression analysis of whole Minors and microdissected Nb and SS cells. METHODS. The authors analyzed gene expression profiles of 10 stroma-poor NTs (NTs-SP) and 9 stroma-rich NTs (NTS-SR) by microarray technology. Nb and SS cells were. isolated by laser microdissection from NTs-SP and NTs-SR and probed with microarrays. Gene expression data were analyzed by the Significance Analysis of Microarrays (SAM) and Game Theory (GT) methods, the latter applied for the first time to microarray data evaluation. RESULTS. SAM identified 84 genes differentially expressed between NTs-SP and NTs-SR, whereas 50 were found by GT. NTs-SP mainly express genes associated with cell replication, nervous system development, and antiapoptotic pathways, whereas NTs-SR express genes of cell-cell communication and apoptosis. Combining SAM and GT, the authors found 16 common genes driving the separation between NTs-SP and NTs-SR. Five genes overexpressed in NTs-SP encode for nuclear proteins (CENPE, EYA1, PBK TOP2A, TFAP2B), whereas only 1 of 11 highly expressed genes in NTs-SR encodes for a nuclear receptor (NR4A2). CONCLUSIONS. The results showed that NT-SP and NT-SR gene signatures differ for a set of genes involved in distinct pathways, and the authors demonstrated a low intratumoral heterogeneity at the mRNA level in both NTs-SP and NTs-SR. The combination of SAM and GT methods may help to better identify gene expression profiling in NTs
Accretion-induced prompt black hole formation in asymmetric neutron star mergers, dynamical ejecta and kilonova signals
We present new numerical relativity results of neutron star mergers with
chirp mass and mass ratios and using
finite-temperature equations of state (EOS), approximate neutrino transport and
a subgrid model for magnetohydrodynamics-induced turbulent viscosity. The EOS
are compatible with nuclear and astrophysical constraints and include a new
microphysical model derived from ab-initio calculations based on the
Brueckner-Hartree-Fock approach. We report for the first time evidence for
accretion-induced prompt collapse in high-mass-ratio mergers, in which the
tidal disruption of the companion and its accretion onto the primary star
determine prompt black hole formation. As a result of the tidal disruption, an
accretion disc of neutron-rich and cold matter forms with baryon masses
, and it is significantly heavier than the remnant discs in
equal-masses prompt collapse mergers. Massive dynamical ejecta of order
also originate from the tidal disruption. They are neutron
rich and expand from the orbital plane with a crescent-like geometry.
Consequently, bright, red and temporally extended kilonova emission is
predicted from these mergers. Our results show that prompt black hole mergers
can power bright electromagnetic counterparts for high-mass-ratio binaries, and
that the binary mass ratio can be in principle constrained from multimessenger
observations.Comment: 20 pages, 21 figures, 4 table
A novel prostate cell type-specific gene signature to interrogate prostate tumor differentiation status and monitor therapeutic response (running title: Phenotypic classification of prostate tumors)
In this study, we extracted prostate cell-specific gene sets (metagenes) to define the epithelial differentiation status of prostate cancers and, using a deconvolution-based strategy, interrogated thousands of primary and metastatic tumors in public gene profiling datasets. We identified a subgroup of primary prostate tumors with low luminal epithelial enrichment (LumElow). LumElow tumors were associated with higher Gleason score and mutational burden, reduced relapse-free and overall survival, and were more likely to progress to castration-resistant prostate cancer (CRPC). Using discriminant function analysis, we generate a predictive 10-gene classifier for clinical implementation. This mini-classifier predicted with high accuracy the luminal status in both primary tumors and CRPCs. Immunohistochemistry for COL4A1, a low- luminal marker, sustained the association of attenuated luminal phenotype with metastatic disease. We found also an association of LumE score with tumor phenotype in genetically engineered mouse models (GEMMs) of prostate cancer. Notably, the metagene approach led to the discovery of drugs that could revert the low luminal status in prostate cell lines and mouse models. This study describes a novel tool to dissect the intrinsic heterogeneity of prostate tumors and provide predictive information on clinical outcome and treatment response in experimental and clinical samples
Prospects for direct detection of black hole formation in neutron star mergers with next-generation gravitational-wave detectors
A direct detection of black hole formation in neutron star mergers would provide invaluable information about matter in neutron star cores and finite temperature effects on the nuclear equation of state. We study black hole formation in neutron star mergers using a set of
190
numerical relativity simulations consisting of long-lived and black-hole-forming remnants. The postmerger gravitational-wave spectrum of a long-lived remnant has greatly reduced power at a frequency
f
greater than
f
peak
, for
f
≳
4
 
 
kHz
, with
f
peak
∈
[
2.5
,
4
]
 
 
kHz
. On the other hand, black-hole-forming remnants exhibit excess power in the same large
f
region and manifest exponential damping in the time domain characteristic of a quasinormal mode. We demonstrate that the gravitational-wave signal from a collapsed remnant is indeed a quasinormal ringing. We report on the opportunity for direct detections of black hole formation with next-generation gravitational-wave detectors such as Cosmic Explorer and Einstein Telescope and set forth the tantalizing prospect of such observations up to a distance of 100 Mpc for an optimally oriented and located source with an SNR of 4
Transcriptional Reprogramming and Novel Therapeutic Approaches for Targeting Prostate Cancer Stem Cells
Prostate cancer is the most common malignancy in men and the second cause of cancer-related deaths in western countries. Despite the progress in the treatment of localized prostate cancer, there is still lack of effective therapies for the advanced forms of the disease. Most patients with advanced prostate cancer become resistant to androgen deprivation therapy (ADT), which remains the main therapeutic option in this setting, and progress to lethal metastatic castration-resistant prostate cancer (mCRPC). Current therapies for prostate cancer preferentially target proliferating, partially differentiated, and AR-dependent cancer cells that constitute the bulk of the tumor mass. However, the subpopulation of tumor-initiating or tumor-propagating stem-like cancer cells is virtually resistant to the standard treatments causing tumor relapse at the primary or metastatic sites. Understanding the pathways controlling the establishment, expansion and maintenance of the cancer stem cell (CSC) subpopulation is an important step toward the development of more effective treatment for prostate cancer, which might enable ablation or exhaustion of CSCs and prevent treatment resistance and disease recurrence. In this review, we focus on the impact of transcriptional regulators on phenotypic reprogramming of prostate CSCs and provide examples supporting the possibility of inhibiting maintenance and expansion of the CSC pool in human prostate cancer along with the currently available methodological approaches. Transcription factors are key elements for instructing specific transcriptional programs and inducing CSC-associated phenotypic changes implicated in disease progression and treatment resistance. Recent studies have shown that interfering with these processes causes exhaustion of CSCs with loss of self-renewal and tumorigenic capability in prostate cancer models. Targeting key transcriptional regulators in prostate CSCs is a valid therapeutic strategy waiting to be tested in clinical trials
Waste Livelihoods Amongst the Poor – Through the Lens of Bricolage
This paper examines two social enterprises and 25+ informal economy micro-entrepreneurs in Kenya who utilize waste materials to generate income, considered through the conceptual lens of bricolage. Waste materials can all be considered as sources of free or discounted materials that in resource-constrained and poor communities might be leveraged to generate income in the absence of employment. This paper explores three key themes that emerge from the research findings, namely the various strategic dimensions of the cases, the networks and social capital they leverage and how these livelihood models relate to various dimensions of bricolage such as improvisation, making do and the process of ‘fiddling’ or recombining resources. The findings also suggest that differing waste livelihoods have different rates of return, or profitability, and differing input requirements of capital, skills and knowledge. The paper also stresses the role of boundary spanning organizations such as NGOs and hybrid/social enterprises
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