81 research outputs found
The Atacama Cosmology Telescope: Two-Season ACTPol Spectra and Parameters
We present the temperature and polarization angular power spectra measured by
the Atacama Cosmology Telescope Polarimeter (ACTPol). We analyze night-time
data collected during 2013-14 using two detector arrays at 149 GHz, from 548
deg of sky on the celestial equator. We use these spectra, and the spectra
measured with the MBAC camera on ACT from 2008-10, in combination with Planck
and WMAP data to estimate cosmological parameters from the temperature,
polarization, and temperature-polarization cross-correlations. We find the new
ACTPol data to be consistent with the LCDM model. The ACTPol
temperature-polarization cross-spectrum now provides stronger constraints on
multiple parameters than the ACTPol temperature spectrum, including the baryon
density, the acoustic peak angular scale, and the derived Hubble constant.
Adding the new data to planck temperature data tightens the limits on damping
tail parameters, for example reducing the joint uncertainty on the number of
neutrino species and the primordial helium fraction by 20%.Comment: 23 pages, 25 figure
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Variations in Nationwide Readmission Patterns after Umbilical Hernia Repair
Up to one in three readmissions occur at a different hospital and are thus missed by current quality metrics. There are no national studies examining 30-day readmission, including to different hospitals, after umbilical hernia repair (UHR). We tested the hypothesis that a large proportion were readmitted to a different hospital, that risk factors for readmission to a different hospital are unique, and that readmission costs differed between the index and different hospitals. The 2013 to 2014 Nationwide Readmissions Database was queried for patients admitted for UHR, and cost was calculated. Multivariate logistic regression identified risk factors for 30-day readmission at index and different hospitals. There were 102,650 admissions for UHR and 8.9 per cent readmissions, of which 15.8 per cent readmissions were to a different hospital. The most common reason for readmission was infection (25.8%). Risk factors for 30-day readmission to any hospital include bowel resection, index admission at a for-profit hospital, Medicare, Medicaid, and Charlson Comorbidity Index ≥ 2. Risk factors for 30-day readmission to a different hospital include elective operation, drug abuse, discharge to a skilled nursing facility, and leaving against medical advice. The median cost of initial admission was higher in those who were readmitted (10,805-11,752 [17,724],
< 0.01). The median cost of readmission was also higher among those readmitted to a different hospital (5497-9227 [16,817],
= 0.02). After UHR, one in six readmissions occur at a different hospital, have unique risk factors, and are costlier. Current hospital benchmarks fail to capture this subpopulation and, therefore, likely underestimate UHR readmissions
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National Analysis of Missed Venous Thromboembolism after Bariatric Surgery: Are We Missing Our Own Complications?
The Atacama Cosmology Telescope: Calibration with WMAP Using Cross-Correlations
We present a new calibration method based on cross-correlations with the Wilkinson Microwave Anisotropy Probe
(WMAP) and apply it to data from the Atacama Cosmology Telescope (ACT). ACT’s observing strategy and mapmaking
procedure allows an unbiased reconstruction of the modes in the maps over a wide range of multipoles. By
directly matching the ACT maps to WMAP observations in the multipole range of 400 < l < 1000, we determine
the absolute calibration with an uncertainty of 2% in temperature. The precise measurement of the calibration error
directly impacts the uncertainties in the cosmological parameters estimated from the ACT power spectra. We also
present a combined map based on ACT and WMAP data that has a high signal-to-noise ratio over a wide range of
multipoles
THE ATACAMA COSMOLOGY TELESCOPE: COSMOLOGY FROM GALAXY CLUSTERS DETECTED VIA THE SUNYAEV-ZEL'DOVICH EFFECT
We present constraints on cosmological parameters based on a sample of Sunyaev-Zel'dovich-selected (SZ-selected) galaxy clusters detected in a millimeter-wave survey by the Atacama Cosmology Telescope. The cluster sample used in this analysis consists of nine optically confirmed high-mass clusters comprising the high-significance end of the total cluster sample identified in 455 deg(2) of sky surveyed during 2008 at 148 GHz. We focus on the most massive systems to reduce the degeneracy between unknown cluster astrophysics and cosmology derived from SZ surveys. We describe the scaling relation between cluster mass and SZ signal with a four-parameter fit. Marginalizing over the values of the parameters in this fit with conservative priors gives sigma(8) = 0.851 +/- 0.115 and omega = -1.14 +/- 0.35 for a spatially flat wCDM cosmological model with Wilkinson Microwave Anisotropy Probe (WMAP) seven-year priors on cosmological parameters. This gives a modest improvement in statistical uncertainty over WMAP seven-year constraints alone. Fixing the scaling relation between the cluster mass and SZ signal to a fiducial relation obtained from numerical simulations and calibrated by X-ray observations, we find sigma(8) = 0.821 +/- 0.044 and omega = -1.05 +/- 0.20. These results are consistent with constraints from WMAP7 plus baryon acoustic oscillations plus Type Ia supernova which give sigma(8) = 0.802 +/- 0.038 and omega = -0.98 +/- 0.053. A stacking analysis of the clusters in this sample compared to clusters simulated assuming the fiducial model also shows good agreement. These results suggest that, given the sample of clusters used here, both the astrophysics of massive clusters and the cosmological parameters derived from them are broadly consistent with current models
Reproducibility Project: Cancer Biology
The Reproducibility Project: Cancer Biology was an initiative to independently replicate selected experiments from a number of high-profile papers in the field of cancer biology. In the end 50 experiments from 23 papers were repeated. The final two outputs from the project recount in detail the challenges the project team encountered while repeating these experiments ('Challenges for assessing replicability in preclinical cancer biology': https://elifesciences.org/articles/67995), and report the results of a meta-analysis that combined the results from all the experiments ('Investigating the replicability of preclinical cancer biology': https://elifesciences.org/articles/71601). The project was a collaboration between the Center for Open Science and Science Exchange with all papers published by eLife
Overview of the medium and high frequency telescopes of the LiteBIRD space mission
LiteBIRD is a JAXA-led Strategic Large-Class mission designed to search for the existence of the primordial gravitational waves produced during the inflationary phase of the Universe, through the measurements of their imprint onto the polarization of the cosmic microwave background (CMB). These measurements, requiring unprecedented sensitivity, will be performed over the full sky, at large angular scales, and over 15 frequency bands from 34 GHz to 448 GHz. The LiteBIRD instruments consist of three telescopes, namely the Low-, Medium-and High-Frequency Telescope (respectively LFT, MFT and HFT). We present in this paper an overview of the design of the Medium-Frequency Telescope (89{224 GHz) and the High-Frequency Telescope (166{448 GHz), the so-called MHFT, under European responsibility, which are two cryogenic refractive telescopes cooled down to 5 K. They include a continuous rotating half-wave plate as the first optical element, two high-density polyethylene (HDPE) lenses and more than three thousand transition-edge sensor (TES) detectors cooled to 100 mK. We provide an overview of the concept design and the remaining specific challenges that we have to face in order to achieve the scientific goals of LiteBIRD
LiteBIRD satellite: JAXA's new strategic L-class mission for all-sky surveys of cosmic microwave background polarization
LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. JAXA selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with its expected launch in the late 2020s using JAXA's H3 rocket. LiteBIRD plans to map the cosmic microwave background (CMB) polarization over the full sky with unprecedented precision. Its main scientific objective is to carry out a definitive search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with an insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. To this end, LiteBIRD will perform full-sky surveys for three years at the Sun-Earth Lagrangian point L2 for 15 frequency bands between 34 and 448 GHz with three telescopes, to achieve a total sensitivity of 2.16 μK-arcmin with a typical angular resolution of 0.5° at 100 GHz. We provide an overview of the LiteBIRD project, including scientific objectives, mission requirements, top-level system requirements, operation concept, and expected scientific outcomes
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