58 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
Observing the Evolution of the Universe
How did the universe evolve? The fine angular scale (l>1000) temperature and
polarization anisotropies in the CMB are a Rosetta stone for understanding the
evolution of the universe. Through detailed measurements one may address
everything from the physics of the birth of the universe to the history of star
formation and the process by which galaxies formed. One may in addition track
the evolution of the dark energy and discover the net neutrino mass.
We are at the dawn of a new era in which hundreds of square degrees of sky
can be mapped with arcminute resolution and sensitivities measured in
microKelvin. Acquiring these data requires the use of special purpose
telescopes such as the Atacama Cosmology Telescope (ACT), located in Chile, and
the South Pole Telescope (SPT). These new telescopes are outfitted with a new
generation of custom mm-wave kilo-pixel arrays. Additional instruments are in
the planning stages.Comment: Science White Paper submitted to the US Astro2010 Decadal Survey.
Full list of 177 author available at http://cmbpol.uchicago.ed
The Atacama Cosmology Telescope: CMB Polarization at
We report on measurements of the cosmic microwave background (CMB) and
celestial polarization at 146 GHz made with the Atacama Cosmology Telescope
Polarimeter (ACTPol) in its first three months of observing. Four regions of
sky covering a total of 270 square degrees were mapped with an angular
resolution of . The map noise levels in the four regions are between 11
and 17 K-arcmin. We present TT, TE, EE, TB, EB, and BB power spectra from
three of these regions. The observed E-mode polarization power spectrum,
displaying six acoustic peaks in the range , is an excellent fit
to the prediction of the best-fit cosmological models from WMAP9+ACT and Planck
data. The polarization power spectrum, which mainly reflects primordial plasma
velocity perturbations, provides an independent determination of cosmological
parameters consistent with those based on the temperature power spectrum, which
results mostly from primordial density perturbations. We find that without
masking any point sources in the EE data at , the Poisson tail of
the EE power spectrum due to polarized point sources has an amplitude less than
K at at 95\% confidence. Finally, we report that
the Crab Nebula, an important polarization calibration source at microwave
frequencies, has 8.7\% polarization with an angle of when smoothed with a Gaussian beam.Comment: 16 pages, 15 figures, 5 table
Modelling human choices: MADeM and decision‑making
Research supported by FAPESP 2015/50122-0 and DFG-GRTK 1740/2. RP and AR are also part of the Research, Innovation and Dissemination Center for Neuromathematics FAPESP grant (2013/07699-0). RP is supported by a FAPESP scholarship (2013/25667-8). ACR is partially supported by a CNPq fellowship (grant 306251/2014-0)
Collecting data on patient experience is not enough: they must be used to improve care
The NHS has been collecting data on patients’ experience of care for over 10 years but few providers are systematically using the information to improve services. Angela Coulter and colleagues argue that a national institute of “user” experience should be set up to draw the data together, determine how to interpret the results, and put them into practice
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Deep Learning to Simulate Contrast-enhanced Breast MRI of Invasive Breast Cancer.
Background There is increasing interest in noncontrast breast MRI alternatives for tumor visualization to increase the accessibility of breast MRI. Purpose To evaluate the feasibility and accuracy of generating simulated contrast-enhanced T1-weighted breast MRI scans from precontrast MRI sequences in biopsy-proven invasive breast cancer with use of deep learning. Materials and Methods Women with invasive breast cancer and a contrast-enhanced breast MRI examination that was performed for initial evaluation of the extent of disease between January 2015 and December 2019 at a single academic institution were retrospectively identified. A three-dimensional, fully convolutional deep neural network simulated contrast-enhanced T1-weighted breast MRI scans from five precontrast sequences (T1-weighted non-fat-suppressed [FS], T1-weighted FS, T2-weighted FS, apparent diffusion coefficient, and diffusion-weighted imaging). For qualitative assessment, four breast radiologists (with 3-15 years of experience) blinded to whether the method of contrast was real or simulated assessed image quality (excellent, acceptable, good, poor, or unacceptable), presence of tumor enhancement, and maximum index mass size by using 22 pairs of real and simulated contrast-enhanced MRI scans. Quantitative comparison was performed using whole-breast similarity and error metrics and Dice coefficient analysis of enhancing tumor overlap. Results Ninety-six MRI examinations in 96 women (mean age, 52 years ± 12 [SD]) were evaluated. The readers assessed all simulated MRI scans as having the appearance of a real MRI scan with tumor enhancement. Index mass sizes on real and simulated MRI scans demonstrated good to excellent agreement (intraclass correlation coefficient, 0.73-0.86; P < .001) without significant differences (mean differences, -0.8 to 0.8 mm; P = .36-.80). Almost all simulated MRI scans (84 of 88 [95%]) were considered of diagnostic quality (ratings of excellent, acceptable, or good). Quantitative analysis demonstrated strong similarity (structural similarity index, 0.88 ± 0.05), low voxel-wise error (symmetric mean absolute percent error, 3.26%), and Dice coefficient of enhancing tumor overlap of 0.75 ± 0.25. Conclusion It is feasible to generate simulated contrast-enhanced breast MRI scans with use of deep learning. Simulated and real contrast-enhanced MRI scans demonstrated comparable tumor sizes, areas of tumor enhancement, and image quality without significant qualitative or quantitative differences. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Slanetz in this issue. An earlier incorrect version appeared online. This article was corrected on January 17, 2023
Hepatitis C Virus Heteroduplex Tracking Assay for Genotype Determination Reveals Diverging Genotype 2 Isolates in Italian Hemodialysis Patients
A heteroduplex tracking assay (HTA) was developed for genetic analyses of the hepatitis C virus (HCV) using single-stranded probes from the core (C)/E1 region. Nucleotide sequencing of reverse transcriptase (RT)-PCR products from 15 Italian dialysis patients confirmed the specificity and accuracy of the HTA genotyping method, which identified 5 of 15 (33.3%) 1b, 7 of 15 (46.7%) 3a, and 3 of 15 (20%) type 2 infections. The genotypes of an additional 12 HCV antibody-positive blood donors from different geographical locations were also in agreement with the genotypes determined by the Inno-LiPA HCV II kit (Innogenetics) and/or restriction fragment length polymorphism (RFLP). Isolates which had between 35 to 40% nucleotide divergence from control subtype 1a, 1b, 2a, 2b, or 3a standards could be typed. Surprisingly, HTA detected one 1b-2 coinfection which was missed by DNA sequencing. Three samples that were designated non-2a or 2b type 2 by HTA were found to be type 2a by both RFLP and direct nucleotide sequencing of the 5′ untranslated region. The genetic distance between patient type 2 and control 2a, 2b, and 2c isolates indicated that a new subtype was present in the population being studied. Serotyping (RIBA serotyping strip immunoblot assay kit) of 23 dialysis patients showed that the genotype could be determined in 6 of 8 (75%) C/E1 RT-PCR-negative and 15 of 23 (65.2%) RT-PCR-positive samples, indicating that the two tests complement each other
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