902 research outputs found
Decaying warm dark matter and neutrino masses
Neutrino masses may arise from spontaneous breaking of ungauged lepton
number. Due to quantum gravity effects the associated Goldstone boson - the
majoron - will pick up a mass. We determine the lifetime and mass required by
cosmic microwave background observations so that the massive majoron provides
the observed dark matter of the Universe. The majoron DDM scenario fits nicely
in models where neutrino masses arise a la seesaw, and may lead to other
possible cosmological implications.Comment: 4 pages, 3 figures. Replaced to match published version. Minor
changes made to address referees' comments. References adde
Impact of general reionization scenarios on extraction of inflationary parameters
Determination of whether the Harrison--Zel'dovich spectrum for primordial
scalar perturbations is consistent with observations is sensitive to
assumptions about the reionization scenario. In light of this result, we
revisit constraints on inflationary models using more general reionization
scenarios. While the bounds on the tensor-to-scalar ratio are largely
unmodified, when different reionization schemes are addressed, hybrid models
are back into the inflationary game. In the general reionization picture, we
reconstruct both the shape and amplitude of the inflaton potential. We find a
broader spectrum of potential shapes when relaxing the simple reionization
restriction. An upper limit of GeV to the amplitude of the potential
is found, regardless of the assumptions on the reionization history.Comment: 10 Pages, 9 figure
Cornering (quasi) degenerate neutrinos with cosmology
In light of the improved sensitivities of cosmological observations, we
examine the status of quasi-degenerate neutrino mass scenarios. Within the
simplest extension of the standard cosmological model with massive neutrinos,
we find that quasi-degenerate neutrinos are severely constrained by present
cosmological data and neutrino oscillation experiments. % % We find that Planck
2018 observations of cosmic microwave background (CMB) anisotropies disfavour
quasi-degenerate neutrino masses at Gaussian 's, while adding
Baryon acoustic oscillations (BAO) data brings the rejection to 5.9's.
% The highest statistical significance with which one would be able to rule out
quasi-degeneracy would arise if the sum of neutrino masses is \meV (the minimum allowed by neutrino oscillation experiments); % indeed a
sensitivity of 15 meV, as expected from a combination of future cosmological
probes, would further improve the rejection level up to 17. % We
discuss the robustness of these projections with respect to assumptions on the
underlying cosmological model, and also compare them with bounds from
decay endpoint and neutrinoless double beta decay studies.Comment: 19 pages, 6 figures, 1 tabl
Regenerative Strategy for Persistent Periprosthetic Leakage around Tracheoesophageal Puncture: Is It an Effective Long-Term Solution?
Autologous tissue-assisted regenerative procedures have been considered effective to close
different types of fistula, including the leakage around tracheoesophageal puncture. The aim of this
study was to retrospectively review 10 years of lipotransfer for persistent periprosthetic leakage
in laryngectomized patients with voice prosthesis. Clinical records of patients who experienced
periprosthetic leakage from December 2009 to December 2019 were reviewed. Patients receiving fat
grafting were included. The leakage around the prosthesis was assessed with a methylene blue test.
Twenty patients experiencing tracheoesophageal fistula enlargement were treated with fat grafting.
At the one-month follow-up, all patients were considered improved with no leakage observed. At six
months, a single injection was sufficient to solve 75% of cases (n 15), whereas 25% (n 5) required a
second procedure. The overall success rate was 80% (n 16). Results remained stable for a follow-up
of 5.54 � 3.97 years. Fat grafting performed around the voice prosthesis, thanks to its volumetric and
regenerative properties, is a valid and lasting option to solve persistent periprosthetic leakage
Sustainable Intensification in Crop-Livestock Systems
Extensive livestock production is the main animal source food system in the Pampas and Campos sub-regions in South America. Beef cattle and sheep convert forage biomass that humans cannot eat into nutrient-dense human-edible foods (meat and milk) and valuable co-products (wool). However, diverse global pressures are acting on Pampas systems including increasing demand for protein sources (food security), climate change, environmental footprint, and competition for land. The integration of small areas of pasture-crop rotations is an alternative for increasing efficiency and sustainable intensification of agroecosystems based on natural grasslands. Rotations led by improved pastures increase the carrying capacity and productivity of traditional Pampas systems, and include crop production (soybean, rice) as an opportunity for farm diversification and resilience. Therefore, mixed crop-livestock systems can feed more people in terms of calories and protein than what is possible with specialized systems. The higher carrying capacity in the area under the rotation may allow less intensive grazing management in larger areas of native grasslands reducing threats to biodiversity. Some of the integrated management practices in crop-livestock systems are perennial pastures to mitigate soil organic carbon losses during cropping, biological nitrogen fixation by legumes, grazing cover crops, crop residue grazing, dual-purpose crops, and harvesting grain and hay for livestock feed. Also, complementary crop and livestock production systems facilitate more efficient nutrient cycling and self-sufficient systems promoting the circular economy concept as a strategic approach toward system sustainability. Key to understanding the potential of mixed crop-livestock systems are productive, environmental, economic, and social factors that determine their performance, as well as trade-offs among them. Development, implementation, maintenance, and analysis of long-term crop-livestock platforms research provides science-based information to address complex biological systems, and to implement innovative public policies at national scale to regulate soil use and to prevent non-sustainable agricultural practices
Inhibition of DNA damage response at telomeres improves the detrimental phenotypes of Hutchinson–Gilford Progeria Syndrome
Hutchinson–Gilford progeria syndrome (HGPS) is a genetic disorder characterized by premature aging features. Cells from HGPS patients express progerin, a truncated form of Lamin A, which perturbs cellular homeostasis leading to nuclear shape alterations, genome instability, heterochromatin loss, telomere dysfunction and premature entry into cellular senescence. Recently, we reported that telomere dysfunction induces the transcription of telomeric non-coding RNAs (tncRNAs) which control the DNA damage response (DDR) at dysfunctional telomeres. Here we show that progerin-induced telomere dysfunction induces the transcription of tncRNAs. Their functional inhibition by sequence-specific telomeric antisense oligonucleotides (tASOs) prevents full DDR activation and premature cellular senescence in various HGPS cell systems, including HGPS patient fibroblasts. We also show in vivo that tASO treatment significantly enhances skin homeostasis and lifespan in a transgenic HGPS mouse model. In summary, our results demonstrate an important role for telomeric DDR activation in HGPS progeroid detrimental phenotypes in vitro and in vivo
A Dynamical Mass Constraint for Pre-Main-Sequence Evolutionary Tracks: The Binary NTT 045251+3016
We present an astrometric/spectroscopic orbital solution for the
pre-main-sequence binary NTT 045251+3016. Our measurements for the primary and
secondary masses are 1.45 +/- 0.19 M_sun and 0.81 +/- 0.09 M_sun, respectively,
and 145 +/- 8 pc for the distance of the system, consistent with prior
estimates for the Taurus-Auriga star-forming region. The evolutionary tracks of
D'Antona & Mazzitelli (1997), Baraffe et al. (1998), and Palla & Stahler (1999)
are tested against these dynamical mass measurements. Due to the intrinsic
color/T_eff variation within the K5 spectral class, each pre-main-sequence
model provides a mass range for the primary. The theoretical mass range derived
from the Baraffe et al. (1998) tracks that use a mixing length parameter
alpha=1.0 is closest to our measured primary mass, deviating between 1.3 and
1.6 sigma. The set of Baraffe et al. (1998) tracks that use alpha=1.9 deviate
between 1.6 and 2.1 sigma from our measured primary mass. The mass range given
by the Palla & Stahler (1999) tracks for the primary star deviate between 1.6
and 2.9 sigma. The D'Antona & Mazzitelli (1997) tracks give a mass range that
deviates by at least 3.0 sigma from our derived primary mass, strongly
suggesting that these tracks are inconsistent with our observation.
Observations of the secondary are less constraining than those of the primary,
but the deviations between the dynamical mass of the secondary and the mass
inferred for the secondary from the various pre-main-sequence tracks mirror the
deviations of the primary star. All of the pre-main-sequence tracks are
consistent with coevality of the components of NTT 045251+3016.Comment: 27 pages, 6 figures, 5 tables -- accepted by A
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