61 research outputs found
Uso del móvil: Estudio de los hábitos de uso del móvil en la comunidad universitaria y del desarrollo de conductas características de las adicciones
Residual strain scanning of alumina-based ceramic composites by neutron diffraction
The objective of this work is to non-destructively determine the residual stress profile in the bulk of two characteristic types of alumina-based composites, with the aim of improving their durability and structural integrity
The Atacama Cosmology Telescope: Galactic Dust Structure and the Cosmic PAH Background in Cross-correlation with WISE
We present a cross-correlation analysis between resolution total
intensity and polarization observations from the Atacama Cosmology Telescope
(ACT) at 150 and 220 GHz and 15 mid-infrared photometry from the Wide-field
Infrared Survey Explorer (WISE) over 107 12.512.5 patches
of sky. We detect a spatially isotropic signal in the WISEACT
cross power spectrum at 30 significance that we interpret as the
correlation between the cosmic infrared background at ACT frequencies and
polycyclic aromatic hydrocarbon (PAH) emission from galaxies in WISE, i.e., the
cosmic PAH background. Within the Milky Way, the Galactic dust spectra are
generally well-described by power laws in over the range 1010, but there is evidence both for variability in the power law index and
for non-power law behavior in some regions. We measure a positive correlation
between WISE total intensity and ACT -mode polarization at 10006000 at 3 in each of 35 distinct 100 deg regions
of the sky, suggesting alignment between Galactic density structures and the
local magnetic field persists to sub-parsec physical scales in these regions.
The distribution of amplitudes in this range across all 107 regions
is biased to positive values, while there is no evidence for such a bias in the
spectra. This work constitutes the highest- measurements of the
Galactic dust spectrum to date and indicates that cross-correlation with
high-resolution mid-infrared measurements of dust emission is a promising tool
for constraining the spatial statistics of dust emission at millimeter
wavelengths.Comment: 20 pages, 14 figures, submitted to Ap
The Atacama Cosmology Telescope: Extragalactic Point Sources in the Southern Surveys at 150, 220 and 280 GHz observed between 2008-2010
We present a multi-frequency, multi-epoch catalog of extragalactic sources.
The catalog is based on 150, 220 and 280 GHz observations carried out in 2008,
2009 and 2010 using the Millimeter Bolometric Array Camera on the Atacama
Cosmology Telescope. We also present and release 280 GHz maps from 2008 and
2010. The catalog contains 695 sources, found in a sky area of
square degrees. It is obtained by cross-matching sources found in 11
sub-catalogs, one for each season and frequency band. Also include are co-added
data from and square degrees using 2 and 3 years of
overlapping observations. We divide the sources into two populations,
synchrotron and dusty emitters, based on their spectral behavior in the 150-220
GHz frequency range. We find 374 synchrotron sources and 321 dusty source
candidates. Cross-matching with catalogs from radio to X-ray results in 264
synchrotron sources (71%) and 89 dusty sources (28%) with counterparts,
suggesting that 232 dusty candidates are not in existing catalogs. We study the
variability and number counts of each population. In the case of synchrotron
sources, we find year-to-year variability up to 60%, with a mean value around
35%. As expected, we find no evidence of dusty source variability. Our number
counts generally agree with previous measurements and models, except for dusty
sources at 280 GHz where some models overestimate our results. We also
characterize the spectral energy distribution of a dusty star-forming galaxy,
ACT-S J065207-551605, using our data and higher frequency observations.Comment: 24 pages, 16 figures, for associated data products see
https://lambda.gsfc.nasa.gov/product/act/act_prod_table.htm
Studying the effects of multiple invasive mammals on Cory’s shearwater nest survival
The most common invasive mammals—mice, rats, and cats—have been introduced to islands around the world, where they continue to negatively affect native biodiversity. The eradication of those invasive mammals has had positive effects on many species of seabirds. However, the removal of one invasive mammal species may result in abundance changes of other species due to trophic and competitive interactions among species. Understanding the overall impact of several invasive species is a key challenge when evaluating the possible effects of eradication programmes. Here we assess the influence of the three most common invasive mammals on nest survival of Cory’s shearwater (Calonectris diomedea). We monitored six breeding colonies over 3 years and measured the activity of mice, rats and cats to examine the influence of invasive mammals on nest survival. We found that nest survival showed a similar temporal trend in all years, with lowest weekly survival probabilities shortly after chicks hatched. Cats were identified as major predators of chicks, but no measure of colony-specific cat activity was able to adequately explain variation in shearwater nest survival. Nest survival was on average 0.38 (95 % confidence interval 0.20–0.53) and varied among colonies as well as over time. We found a small positive influence of rats on nest survival, which may indicate that the presence of small rodents as alternative prey may reduce cat predation of chicks. Our findings suggest that the eradication of rodents alone may exacerbate the adverse effects of cats on shearwater nest survival.This work was included in the project LIFE07 NAT/P/000649 ‘Safe Islands for Seabirds’, coordinated by the Portuguese Society for the Study of Birds and co-financed by the European Commission.Peer Reviewe
The Simons Observatory: Galactic Science Goals and Forecasts
Observing in six frequency bands from 27 to 280 GHz over a large sky area,
the Simons Observatory (SO) is poised to address many questions in Galactic
astrophysics in addition to its principal cosmological goals. In this work, we
provide quantitative forecasts on astrophysical parameters of interest for a
range of Galactic science cases. We find that SO can: constrain the frequency
spectrum of polarized dust emission at a level of
and thus test models of dust composition that predict that in
polarization differs from that measured in total intensity; measure the
correlation coefficient between polarized dust and synchrotron emission with a
factor of two greater precision than current constraints; exclude the
non-existence of exo-Oort clouds at roughly 2.9 if the true fraction is
similar to the detection rate of giant planets; map more than 850 molecular
clouds with at least 50 independent polarization measurements at 1 pc
resolution; detect or place upper limits on the polarization fractions of
CO(2-1) emission and anomalous microwave emission at the 0.1% level in select
regions; and measure the correlation coefficient between optical starlight
polarization and microwave polarized dust emission in patches for all
lines of sight with cm. The goals and
forecasts outlined here provide a roadmap for other microwave polarization
experiments to expand their scientific scope via Milky Way astrophysics.Comment: Submitted to AAS journals. 33 pages, 10 figure
The Atacama Cosmology Telescope: Mitigating the impact of extragalactic foregrounds for the DR6 CMB lensing analysis
We investigate the impact and mitigation of extragalactic foregrounds for the
CMB lensing power spectrum analysis of Atacama Cosmology Telescope (ACT) data
release 6 (DR6) data. Two independent microwave sky simulations are used to
test a range of mitigation strategies. We demonstrate that finding and then
subtracting point sources, finding and then subtracting models of clusters, and
using a profile bias-hardened lensing estimator, together reduce the fractional
biases to well below statistical uncertainties, with the inferred lensing
amplitude, , biased by less than . We also show
that another method where a model for the cosmic infrared background (CIB)
contribution is deprojected and high frequency data from Planck is included has
similar performance. Other frequency-cleaned options do not perform as well,
incurring either a large noise cost, or resulting in biased recovery of the
lensing spectrum. In addition to these simulation-based tests, we also present
null tests performed on the ACT DR6 data which test for sensitivity of our
lensing spectrum estimation to differences in foreground levels between the two
ACT frequencies used, while nulling the CMB lensing signal. These tests pass
whether the nulling is performed at the map or bandpower level. The
CIB-deprojected measurement performed on the DR6 data is consistent with our
baseline measurement, implying contamination from the CIB is unlikely to
significantly bias the DR6 lensing spectrum. This collection of tests gives
confidence that the ACT DR6 lensing measurements and cosmological constraints
presented in companion papers to this work are robust to extragalactic
foregrounds.Comment: Companion paper to Qu et al and Madhavacheril et a
Thermo-Mechanical Treatment Effects on Stress Relaxation and Hydrogen Embrittlement of Cold-Drawn Eutectoid Steels
The effects of the temperature and stretching levels used in the stress-relieving treatment of cold-drawn eutectoid steel wires are evaluated with the aim of improving the stress relaxation behavior and the resistance to hydrogen embrittlement. Five industrial treatments are studied, combining three temperatures (330, 400, and 460 °C) and three stretching levels (38, 50 and 64% of the rupture load). The change of the residual stress produced by the treatments is taken into consideration to account for the results. Surface residual stresses allow us to explain the time to failure in standard hydrogen embrittlement test
Exploring cosmic origins with CORE: Gravitational lensing of the CMB
Lensing of the CMB is now a well-developed probe of large-scale clustering
over a broad range of redshifts. By exploiting the non-Gaussian imprints of
lensing in the polarization of the CMB, the CORE mission can produce a clean
map of the lensing deflections over nearly the full-sky. The number of high-S/N
modes in this map will exceed current CMB lensing maps by a factor of 40, and
the measurement will be sample-variance limited on all scales where linear
theory is valid. Here, we summarise this mission product and discuss the
science that it will enable. For example, the summed mass of neutrinos will be
determined to an accuracy of 17 meV combining CORE lensing and CMB two-point
information with contemporaneous BAO measurements, three times smaller than the
minimum total mass allowed by neutrino oscillations. In the search for B-mode
polarization from primordial gravitational waves with CORE, lens-induced
B-modes will dominate over instrument noise, limiting constraints on the
gravitational wave power spectrum amplitude. With lensing reconstructed by
CORE, one can "delens" the observed polarization internally, reducing the
lensing B-mode power by 60%. This improves to 70% by combining lensing and CIB
measurements from CORE, reducing the error on the gravitational wave amplitude
by 2.5 compared to no delensing (in the null hypothesis). Lensing measurements
from CORE will allow calibration of the halo masses of the 40000 galaxy
clusters that it will find, with constraints dominated by the clean
polarization-based estimators. CORE can accurately remove Galactic emission
from CMB maps with its 19 frequency channels. We present initial findings that
show that residual Galactic foreground contamination will not be a significant
source of bias for lensing power spectrum measurements with CORE. [abridged
Evolution after Anti-TNF Discontinuation in Patients with Inflammatory Bowel Disease: A Multicenter Long-Term Follow-Up Study
OBJECTIVES:The aims of this study were to assess the risk of relapse after discontinuation of anti-tumor necrosis factor (anti-TNF) drugs in patients with inflammatory bowel disease (IBD), to identify the factors associated with relapse, and to evaluate the overcome after retreatment with the same anti-TNF in those who relapsed.METHODS:This was a retrospective, observational, multicenter study. IBD patients who had been treated with anti-TNFs and in whom these drugs were discontinued after clinical remission was achieved were included.RESULTS:A total of 1, 055 patients were included. The incidence rate of relapse was 19% and 17% per patient-year in Crohn''s disease and ulcerative colitis patients, respectively. In both Crohn''s disease and ulcerative colitis patients in deep remission, the incidence rate of relapse was 19% per patient-year. The treatment with adalimumab vs. infliximab (hazard ratio (HR)=1.29; 95% confidence interval (CI)=1.01-1.66), elective discontinuation of anti-TNFs (HR=1.90; 95% CI=1.07-3.37) or discontinuation because of adverse events (HR=2.33; 95% CI=1.27-2.02) vs. a top-down strategy, colonic localization (HR=1.51; 95% CI=1.13-2.02) vs. ileal, and stricturing behavior (HR=1.5; 95% CI=1.09-2.05) vs. inflammatory were associated with a higher risk of relapse in Crohn''s disease patients, whereas treatment with immunomodulators after discontinuation (HR=0.67; 95% CI=0.51-0.87) and age (HR=0.98; 95% CI=0.97-0.99) were protective factors. None of the factors were predictive in ulcerative colitis patients. Retreatment of relapse with the same anti-TNF was effective (80% responded) and safe.CONCLUSIONS:The incidence rate of inflammatory bowel disease relapse after anti-TNF discontinuation is relevant. Some predictive factors of relapse after anti-TNF withdrawal have been identified. Retreatment with the same anti-TNF drug was effective and safe
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