130 research outputs found
Electrically controllable magnetism in twisted bilayer graphene
Twisted graphene bilayers develop highly localised states around AA-stacked
regions for small twist angles. We show that interaction effects may induce
either an antiferromagnetic (AF) and a ferromagnetic (F) polarization of said
regions, depending on the electrical bias between layers. Remarkably,
F-polarised AA regions under bias develop spiral magnetic ordering, with a
relative misalignment between neighbouring regions due to a
frustrated antiferromagnetic exchange. This remarkable spiral magnetism emerges
naturally without the need of spin-orbit coupling, and competes with the more
conventional lattice-antiferromagnetic instability, which interestingly
develops at smaller bias under weaker interactions than in monolayer graphene,
due to Fermi velocity suppression. This rich and electrically controllable
magnetism could turn twisted bilayer graphene into an ideal system to study
frustrated magnetism in two dimensions, with interesting potential also for a
range of applications.Comment: 7 pages, 3 figures. Minor correction
Tests of redshift-space distortions models in configuration space for the analysis of the BOSS final data release
Observations of redshift-space distortions in spectroscopic galaxy surveys
offer an attractive method for observing the build-up of cosmological
structure, which depends both on the expansion rate of the Universe and our
theory of gravity. In preparation for analysis of redshift-space distortions
from the Baryon Oscillation Spectroscopic Survey (BOSS) final data release we
compare a number of analytic and phenomenological `streaming' models, specified
in configuration space, to mock catalogs derived in different ways from several
N-body simulations. The galaxies in each mock catalog have properties similar
to those of the higher redshift galaxies measured by BOSS but differ in the
details of how small-scale velocities and halo occupancy are determined. We
find that all of the analytic models fit the simulations over a limited range
of scales while failing at small scales. We discuss which models are most
robust and on which scales they return reliable estimates of the rate of growth
of structure: we find that models based on some form of resummation can fit our
N-body data for BOSS-like galaxies above Mpc well enough to return
unbiased parameter estimates.Comment: 12 pages, 11 figures, matches version accepted by MNRA
The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Angular clustering tomography and its cosmological implications
We investigate the cosmological implications of studying galaxy clustering
using a tomographic approach applied to the final BOSS DR12 galaxy sample,
including both auto- and cross-correlation functions between redshift shells.
We model the signal of the full shape of the angular correlation function,
, in redshift bins using state-of-the-art modelling of
non-linearities, bias and redshift-space distortions. We present results on the
redshift evolution of the linear bias of BOSS galaxies, which cannot be
obtained with traditional methods for galaxy-clustering analysis. We also
obtain constraints on cosmological parameters, combining this tomographic
analysis with measurements of the cosmic microwave background (CMB) and type Ia
supernova (SNIa). We explore a number of cosmological models, including the
standard CDM model and its most interesting extensions, such as
deviations from w_\rm{DE} = -1, non-minimal neutrino masses, spatial
curvature and deviations from general relativity using the growth-index
parametrisation. These results are, in general, comparable to the most
precise present-day constraints on cosmological parameters, and show very good
agreement with the standard model. In particular, combining CMB,
and SNIa, we find a value of w_\rm{DE} consistent with
to a precision better than 5\% when it is assumed to be constant in time, and
better than 6\% when we also allow for a spatially-curved Universe.Comment: 21 pages, 18 figures, accepted for publication MNRAS. The data used
in this analysis is publicly available at
https://sdss3.org/science/boss_publications.ph
Relapses and recurrences in giant cell arteritis: a population-based study of patients with biopsy-proven disease from northwestern Spain
We conducted the present study to determine the incidence of disease flares (relapses and recurrences) in a series of patients with biopsy-proven giant cell arteritis (GCA). We assessed a series of 174 patients who were diagnosed with biopsy-proven GCA, uniformly treated, and followed at the rheumatology division of Hospital Xeral-Calde (Lugo, Spain), the single rheumatology division for a well-defined population. All of them were followed for at least 1 year after the disease diagnosis. Seventy-one (40.8%) experienced relapses or recurrences of the disease. Patients who had relapses or recurrences did not show clinical differences when compared with the remaining biopsy-proven GCA patients. However, the total duration of corticosteroid therapy was significantly longer in those patients who had relapses or recurrences of the disease. The median dose of prednisone and the median duration of corticosteroid treatment at the time of the first relapse were 5 mg/d and 16 months, respectively. Headache (52%) was the most common feature at the time of the first relapse. Polymyalgia rheumatica manifestations occurred in 30% of the patients at that time. However, none of them developed visual loss. Thirty-two patients experienced recurrences of the disease when prednisone dose had been discontinued. The median time from the disease diagnosis to the time of the recurrence was 23 months. The presence of anemia (hemoglobin <12 g/dL) at the time of disease diagnosis was the best predictor of relapses or recurrences of GCA (odds ratio, 2.17; 95% confidence interval, 1.02-4.62; p = 0.04). The results from the present study confirm that relapses and recurrences are frequent in homogenously treated patients with biopsy-proven GCA. A chronic inflammatory response manifested by anemia at the time of disease diagnosis may predict the development of disease flares
POU1F1 transcription factor induces metabolic reprogramming and breast cancer progression via LDHA regulation
Metabolic reprogramming is considered hallmarks of cancer. Aerobic glycolysis in tumors cells has been well-known for almost a century, but specific factors that regulate lactate generation and the effects of lactate in both cancer cells and stroma are not yet well understood. In the present study using breast cancer cell lines, human primary cultures of breast tumors, and immune deficient murine models, we demonstrate that the POU1F1 transcription factor is functionally and clinically related to both metabolic reprogramming in breast cancer cells and fibroblasts activation. Mechanistically, we demonstrate that POU1F1 transcriptionally regulates the lactate dehydrogenase A (LDHA) gene. LDHA catalyzes pyruvate into lactate instead of leading into the tricarboxylic acid cycle. Lactate increases breast cancer cell proliferation, migration, and invasion. In addition, it activates normal-associated fibroblasts (NAFs) into cancer-associated fibroblasts (CAFs). Conversely, LDHA knockdown in breast cancer cells that overexpress POU1F1 decreases tumor volume and [18F]FDG uptake in tumor xenografts of mice. Clinically, POU1F1 and LDHA expression correlate with relapse- and metastasis-free survival. Our data indicate that POU1F1 induces a metabolic reprogramming through LDHA regulation in human breast tumor cells, modifying the phenotype of both cancer cells and fibroblasts to promote cancer progressionThis study was supported by FEDER/Ministerio de Ciencia, Innovación y Universidades- Agencia Estatal de Investigación-PGC2018-100776-B-I00 and from Conselleria de Cultura, Educación e Ordenacion Universitaria (GPC2014/001), AM-O was supported by an FPU grant (Ministerio de Educación—FPU14/00548)S
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS anisotropic galaxy clustering
With the largest spectroscopic galaxy survey volume drawn from the SDSS-III
Baryon Oscillation Spectroscopic Survey (BOSS), we can extract cosmological
constraints from the measurements of redshift and geometric distortions at
quasi-linear scales (e.g. above 50 Mpc). We analyze the broad-range
shape of the monopole and quadrupole correlation functions of the BOSS Data
Release 12 (DR12) CMASS galaxy sample, at the effective redshift , to
obtain constraints on the Hubble expansion rate , the angular-diameter
distance , the normalized growth rate , and the
physical matter density . We obtain robust measurements by
including a polynomial as the model for the systematic errors, and find it
works very well against the systematic effects, e.g., ones induced by stars and
seeing. We provide accurate measurements ,
, , = , , , ,
where is the comoving sound horizon at the drag epoch and
Mpc is the sound scale of the fiducial cosmology used in
this study. The parameters which are not well constrained by our galaxy
clustering analysis are marginalized over with wide flat priors. Since no
priors from other data sets, e.g., cosmic microwave background (CMB), are
adopted and no dark energy models are assumed, our results from BOSS CMASS
galaxy clustering alone may be combined with other data sets, i.e., CMB, SNe,
lensing or other galaxy clustering data to constrain the parameters of a given
cosmological model. The uncertainty on the dark energy equation of state
parameter, , from CMB+CMASS is about 8 per cent. The uncertainty on the
curvature fraction, , is 0.3 per cent. We do not find deviation from
flat CDM.Comment: 15 pages, 11 figures. The latest version matches and the accepted
version by MNRAS. A bug in the first version has been identified and fixed in
the new version. We have redone the analysis with newest data (BOSS DR12
PET study of intravitreal adalimumab pharmacokinetics in a uveitis rat model
X. García-Otero is grateful to the IDIS (Health Research Institute of Santiago de Compostela) for financing his predoctoral research fellowship. C. Mondelo-García, E. Bandín-Vilar and A. Fernández-Ferreiro are grateful to the Carlos III Health Institute for financing their personnel contracts: JR20/00026, CM20/00135 and JR18/00014.S
SDSS-III Baryon Oscillation Spectroscopic Survey data release 12 : galaxy target selection and large-scale structure catalogues
The Baryon Oscillation Spectroscopic Survey (BOSS), part of the Sloan Digital Sky Survey (SDSS) III project, has provided the largest survey of galaxy redshifts available to date, in terms of both the number of galaxy redshifts measured by a single survey, and the effective cosmological volume covered. Key to analysing the clustering of these data to provide cosmological measurements is understanding the detailed properties of this sample. Potential issues include variations in the target catalogue caused by changes either in the targeting algorithm or properties of the data used, the pattern of spectroscopic observations, the spatial distribution of targets for which redshifts were not obtained, and variations in the target sky density due to observational systematics. We document here the target selection algorithms used to create the galaxy samples that comprise BOSS. We also present the algorithms used to create large-scale structure catalogues for the final Data Release (DR12) samples and the associated random catalogues that quantify the survey mask. The algorithms are an evolution of those used by the BOSS team to construct catalogues from earlier data, and have been designed to accurately quantify the galaxy sample. The code used, designated mksample, is released with this paper.Publisher PDFPeer reviewe
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey : measuring DA and H at z = 0.57 from the baryon acoustic peak in the Data Release 9 spectroscopic Galaxy sample
We present measurements of the angular diameter distance to and Hubble parameter at z = 0.57 from the measurement of the baryon acoustic peak in the correlation of galaxies from the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey. Our analysis is based on a sample from Data Release 9 of 264 283 galaxies over 3275 square degrees in the redshift range 0.43 < z < 0.70. We use two different methods to provide robust measurement of the acoustic peak position across and along the line of sight in order to measure the cosmological distance scale. We find DA(0.57) = 1408 ± 45 Mpc and H(0.57) = 92.9 ± 7.8 km s−1 Mpc−1 for our fiducial value of the sound horizon. These results from the anisotropic fitting are fully consistent with the analysis of the spherically averaged acoustic peak position presented in Anderson et al. Our distance measurements are a close match to the predictions of the standard cosmological model featuring a cosmological constant and zero spatial curvature.Publisher PDFPeer reviewe
- …