1,070 research outputs found
An improved measurement of baryon acoustic oscillations from the correlation function of galaxy clusters at
We detect the peak of baryon acoustic oscillations (BAO) in the two-point
correlation function of a spectroscopic sample of clusters selected
from the Sloan Digital Sky Survey. Galaxy clusters, as tracers of massive dark
matter haloes, are highly biased structures. The linear bias of the sample
considered in this work, that we estimate from the projected correlation
function, is . Thanks to the high signal in the
cluster correlation function and to the accurate spectroscopic redshift
measurements, we can clearly detect the BAO peak and determine its position,
, with high accuracy, despite the relative paucity of the sample. Our
measurement, , is in good agreement
with previous estimates from large galaxy surveys, and has a similar
uncertainty. The BAO measurement presented in this work thus provides a new
strong confirmation of the concordance cosmological model and demonstrates the
power and promise of galaxy clusters as key probes for cosmological
applications based on large scale structures.Comment: 10 pages, 7 figure, accepted for publication in MNRA
Improved drought tolerance in wheat is required to unlock the production potential of the Brazilian Cerrado.
ABSTRACT Improving rainfed wheat cultivation in central Brazil, where the Cerrado biome (Brazilian savanna) is predominant, remains a bottleneck for future increases in domestic wheat production. In the Cerrado, the limited water availability during the wheat-growing season is an obstacle to increase wheat yield. To address this issue, the physiological and molecular drought response of wheat and the environmental conditions of this region must be better understood. In this review, we characterized the impact of drought on rainfed wheat production in the Cerrado. Based on the peculiarities of this environment, we suggest that certain traits should be prioritized in selection. These traits and their molecular basis are important to raise wheat yields in the Cerrado and also to improve food security in Brazil, one of the top wheat-importing countries in the world
Phenotypical Characters Associated with the Loss of the Seed and the Production of Biomass in \u3ci\u3ePanicum coloratum\u3c/i\u3e var. \u3ci\u3emakarikariense\u3c/i\u3e
Since the beginning of humanity, plants have been manipulated by humans by artificial selection to obtain changes in their characteristics. This progress has been achieved through the domestication of the species. Panicum coloratum is a species of summer perennial grass, megathermic, tolerates waterlogging, cold and slightly saline soils. It is of African origin and used as fodder in various parts of the world. In Argentina around 130.500 hectares are sown, the most widespread varieties are: var. coloratum, and var. makarikariense Goossens. Its characteristics of determined flowering and ununiform ripening within the panicle, added to a very low retention of the seeds after maturation, establish serious difficulties in harvesting quality seeds. Megathermic forage species are good producers in forage quantity and, in turn, possess good quality. The objective of the work was to study the dynamics of seed dehiscence and the forage production of two cultivars of Panicum coloratum var. makarikariense (cv. Kapivera and cv. Bambatsi). The seed fall was evaluated weekly for 70 days between March-May 2017 and 2019 on 15 random inflorescences of each cultivar. Once the seed harvest was completed in May 2017 and 2019, the panicles were cut and the panicle height, panicle length, rachis length, wet weight, dry weight and percentage of dry matter were analyzed. Through a χ² distribution, it was found that there is experimental evidence that indicates that the dynamics of seed fall are different among cultivars. An analysis of main components was carried out in each year under study to simultaneously evaluate all the variables related to biomass, in the two ACPs mentioned there was not a defined grouping of the plants according to the cultivation to which they correspond
Impact of COVID-19 pandemic lockdown on narcolepsy type 1 management
Study Objectives: Narcolepsy type 1 (NT1) is a chronic rare hypersomnia of central origin requiring a combination of behavioral and pharmacological treatments. During the coronavirus disease 2019 (COVID-19) pandemic, in Italy the population was forced into a lockdown. With this study, we aimed to describe the lockdown impact on NT1 symptom management, according to different patients' working schedule. Methods: In the period between 10 April and 15 May 2020, we performed routine follow-up visits by telephone (as recommended during the COVID-19 emergency) to 50 patients >18 years old (40% males) under stable long-term treatment. We divided patients into three groups: unchanged working schedule, forced working/studying at home, and those who lost their job (“lost occupation”). Current sleep–wake habit and symptom severity were compared with prelockdown assessment (six months before) in the three patient groups. Results: At assessment, 20, 22, and eight patients belonged to the unchanged, working/studying at home, and lost occupation groups, respectively. While in the lost occupation group, there were no significant differences compared with prepandemic assessment, the patients with unchanged schedules reported more nocturnal awakenings, and NT1 patients working/studying at home showed an extension of nocturnal sleep time, more frequent daytime napping, improvement of daytime sleepiness, and a significant increase in their body mass index. Sleep-related paralysis/hallucinations, automatic behaviors, cataplexy, and disturbed nocturnal sleep did not differ. Conclusions: Narcolepsy type 1 patients working/studying at home intensified behavioral interventions (increased nocturnal sleep time and daytime napping) and ameliorated daytime sleepiness despite presenting with a slight, but significant, increase of weight
Passive galaxies as tracers of cluster environments at z~2
Even 10 billion years ago, the cores of the first galaxy clusters are often
found to host a characteristic population of massive galaxies with already
suppressed star formation. Here we search for distant cluster candidates at z~2
using massive passive galaxies as tracers. With a sample of ~40
spectroscopically confirmed passive galaxies at 1.3<z<2.1, we tune photometric
redshifts of several thousands passive sources in the full 2 sq.deg. COSMOS
field. This allows us to map their density in redshift slices, probing the
large scale structure in the COSMOS field as traced by passive sources. We
report here on the three strongest passive galaxy overdensities that we
identify in the redshift range 1.5<z<2.5. While the actual nature of these
concentrations is still to be confirmed, we discuss their identification
procedure, and the arguments supporting them as candidate galaxy clusters
(likely mid-10^13 M_sun range). Although this search approach is likely biased
towards more evolved structures, it has the potential to select still rare,
cluster-like environments close to their epoch of first appearance, enabling
new investigations of the evolution of galaxies in the context of structure
growth.Comment: 5 pages, 5 figures; A&A Letters, in pres
New constraints on cosmological parameters and neutrino properties using the expansion rate of the Universe to z~1.75
We have assembled a compilation of observational Hubble parameter
measurements estimated with the differential evolution of cosmic chronometers,
in the redshift range 0<z<1.75. This sample has been used, in combination with
CMB data and with the most recent estimate of the Hubble constant H_0, to
derive new constraints on several cosmological parameters. The new Hubble
parameter data are very useful to break some of the parameter degeneracies
present in CMB-only analysis, and to constrain possible deviations from the
standard (minimal) flat \Lambda CDM model. The H(z) data are especially
valuable in constraining \Omega_k and \Omega_DE in models that allow a
variation of those parameters, yielding constraints that are competitive with
those obtained using Supernovae and/or baryon acoustic oscillations. We also
find that our H(z) data are important to constrain parameters that do no affect
directly the expansion history, by breaking or reducing degeneracies with other
parameters. We find that Nrel=3.45\pm0.33 using WMAP 7-years data in
combination with South Pole Telescope data and our H(z) determinations
(Nrel=3.71\pm0.45 using Atacama Cosmology Telescope data instead of South Pole
Telescope). We exclude Nrel>4 at 95% CL (74% CL) using the same datasets
combinations. We also put competitive limits on the sum of neutrino masses,
\Sigma m_\nu<0.24 eV at 68% confidence level. These results have been proven to
be extremely robust to many possible systematic effects, such as the initial
choice of stellar population synthesis model adopted to estimate H(z) and the
progenitor-bias.Comment: 18 pages, 17 figures, 7 tables, published in JCAP. It is a companion
to Moresco et al. (2012a, http://arxiv.org/abs/1201.3609) and Jimenez et al.
(2012, http://arxiv.org/abs/1201.3608). The H(z) data can be downloaded at
http://www.physics-astronomy.unibo.it/en/research/areas/astrophysics/cosmology-with-cosmic-chronometer
Taxonomic distribution of neoplasia among non-domestic felid species under managed care
As evidenced by numerous case reports from zoos, neoplasia in felids is common, but most reports are limited to Panthera species in North America or Europe. In order to obtain a wider epidemiologic understanding of neoplasia distribution, necropsy records at seven facilities (USA, Mexico, Colombia, Peru, and Brazil) were evaluated. In contrast to others, this study population (195 cases, 16 species), included many non-Panthera felids. Overall neoplasia prevalence was 28.2% (55/195). Panthera species had a higher prevalence of neoplasia than non-Panthera species (52.5%; vs. 13.0%). Lions (66.7%), jaguars (55.0%), and tigers (31.3%) had the highest species-specific prevalence of neoplasia. Neoplasms in Panthera species were more frequently malignant than in non-Panthera (86.1% vs. 55.6%). The systems most commonly a_ected were the reproductive, hematolymphoid, and respiratory. The range of management conditions and more varied genetic backgrounds support a robust taxonomic pattern and suggest that the reported propensity for neoplasia in jaguars may have a genetic basis at a taxonomic level higher than species, as lions and tigers also have high prevalence. Given the high prevalence of neoplasia and high likelihood of malignancy, routine medical exams in all nondomestic felids, but Panthera species in particular, should include thorough assessments of any clinical signs of neoplasia
Restrictions on the lifetime of sterile neutrinos from primordial nucleosynthesis
We analyze the influence of decaying sterile neutrinos with the masses in the
range 1-140 MeV on the primordial Helium-4 abundance, explicitly solving the
Boltzmann equations for all particle species, taking into account neutrino
flavour oscillations, and paying special attention to systematic uncertainties.
We show that the Helium abundance depends only on the sterile neutrino lifetime
and not on the way the active-sterile mixing is distributed between flavours,
and derive an upper bound on the lifetime. We also demonstrate that the recent
results of Izotov & Thuan [arXiv:1001.4440], who find 2sigma higher than
predicted by the standard primordial nucleosynthesis value of Helium-4
abundance, are consistent with the presence in the plasma of sterile neutrinos
with the lifetime 0.01-2 seconds. The decay of these particles perturbs the
spectra of (decoupled) neutrinos and heats photons, changing the ratio of
neutrino to photon energy density, that can be interpreted as extra neutrino
species at the recombination epoch.Comment: 17 pp. + Appendices. Analysis of deuterium bounds and more accurate
account of CMB bounds on Helium-4 is added. Final version to appear in JCA
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