1,940 research outputs found
EBEX: A balloon-borne CMB polarization experiment
EBEX is a NASA-funded balloon-borne experiment designed to measure the
polarization of the cosmic microwave background (CMB). Observations will be
made using 1432 transition edge sensor (TES) bolometric detectors read out with
frequency multiplexed SQuIDs. EBEX will observe in three frequency bands
centered at 150, 250, and 410 GHz, with 768, 384, and 280 detectors in each
band, respectively. This broad frequency coverage is designed to provide
valuable information about polarized foreground signals from dust. The
polarized sky signals will be modulated with an achromatic half wave plate
(AHWP) rotating on a superconducting magnetic bearing (SMB) and analyzed with a
fixed wire grid polarizer. EBEX will observe a patch covering ~1% of the sky
with 8' resolution, allowing for observation of the angular power spectrum from
\ell = 20 to 1000. This will allow EBEX to search for both the primordial
B-mode signal predicted by inflation and the anticipated lensing B-mode signal.
Calculations to predict EBEX constraints on r using expected noise levels show
that, for a likelihood centered around zero and with negligible foregrounds,
99% of the area falls below r = 0.035. This value increases by a factor of 1.6
after a process of foreground subtraction. This estimate does not include
systematic uncertainties. An engineering flight was launched in June, 2009,
from Ft. Sumner, NM, and the long duration science flight in Antarctica is
planned for 2011. These proceedings describe the EBEX instrument and the North
American engineering flight.Comment: 12 pages, 9 figures, Conference proceedings for SPIE Millimeter,
Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V
(2010
KURVS: The outer rotation curve shapes and dark matter fractions of star-forming galaxies
We present first results from the KMOS Ultra-deep Rotation Velocity Survey
(KURVS), aimed at studying the outer rotation curves shape and dark matter
content of 22 star-forming galaxies at . These galaxies represent
`typical' star-forming discs at , being located within the
star-forming main sequence and stellar mass-size relation with stellar masses
log. We extract
individual rotation curves out to 4 times the effective radius, on average, or
kpc. Most rotation curves are flat or rising between three- and
six-disc scale radii. Only three objects with dispersion-dominated dynamics
() have declining outer rotation curves at more
than 5 significance. After accounting for seeing and pressure support,
the nine rotation-dominated discs with have
average dark matter fractions of at the effective radius, similar
to local discs. Together with previous observations of star-forming galaxies at
cosmic noon, our measurements suggest a trend of declining dark matter fraction
with increasing stellar mass and stellar mass surface density at the effective
radius. Simulated EAGLE galaxies are in quantitative agreement with
observations up to log, and over-predict the dark matter fraction of galaxies with higher
mass surface densities by a factor of . We conclude that the dynamics
of typical rotationally-supported discs at is dominated by dark
matter from effective radius scales, in broad agreement with cosmological
models. The tension with observations at high stellar mass surface density
suggests that the prescriptions for baryonic processes occurring in the most
massive galaxies (such as bulge growth and quenching) need to be reassessed.Comment: 23 pages, 9 figures. Resubmitted to MNRAS after addressing the
referee's comments. Abstract slightly modified to compile with the arXiv
formattin
The association between indwelling urinary catheter use in the elderly and urinary tract infection in acute care
BACKGROUND: The use of indwelling urinary catheters (IUCs) is thought to be the most significant risk factor for developing nosocomial urinary tract infections (UTIs). However, it is unclear how many elderly patients have preexisting bacteriuria prior to IUC placement. The purpose of this study was to determine 1) the frequency and appropriateness of IUC use in the Emergency Department (ED) in elderly patients admitted to our acute care hospital, 2) the percentage of elderly patients with an IUC who were discharged from the hospital with a diagnosis of UTI, 3) the percentage of patients with IUCs who were diagnosed and treated for UTI in the ED or who had admission bacteriuria ≥10(5 )organisms/ml indicating preexisting UTI, and 4) the percentage of patients with no indication of UTI on admission who had inappropriately placed IUCs and subsequently were diagnosed with a UTI. METHODS: Retrospective chart review. Chi square used to test significance of differences in proportions. RESULTS: Seventy three percent of patients who received an IUC in the ED were elderly (≥65 years old). During the study period, 277 elderly patients received an IUC prior to admission. Of these, 77 (28%) were diagnosed with UTI during their hospitalization. Fifty three (69%) of those diagnosed with a UTI by discharge either had the UTI diagnosed in the ED or had bacteriuria ≥10(5 )organisms/ml prior to IUC placement. Of the 24 elderly patients who developed a catheter-associated UTI (i.e., 9% of the elderly population who received an IUC), 11 of the IUCs were placed inappropriately. Thus, 4% of elderly patients with no indication of UTI on admission who received an inappropriate IUC in the ED had a primary or secondary diagnosis of UTI by discharge. The overall rate of nosocomial UTI due to an inappropriately placed IUC was the same in males and females. CONCLUSION: This study indicates that the strong association between IUC use and UTI may be partly explained by the high prevalence of preexisting UTI prior to IUC placement. Further prospective studies are needed to clarify the true risk vs benefit ratio for IUC use in acutely ill elderly patients
Quantifying intra-tumoral genetic heterogeneity of glioblastoma toward precision medicine using MRI and a data-inclusive machine learning algorithm
Glioblastoma (GBM) is one of the most aggressive and lethal human cancers.
Intra-tumoral genetic heterogeneity poses a significant challenge for
treatment. Biopsy is invasive, which motivates the development of non-invasive,
MRI-based machine learning (ML) models to quantify intra-tumoral genetic
heterogeneity for each patient. This capability holds great promise for
enabling better therapeutic selection to improve patient outcomes. We proposed
a novel Weakly Supervised Ordinal Support Vector Machine (WSO-SVM) to predict
regional genetic alteration status within each GBM tumor using MRI. WSO-SVM was
applied to a unique dataset of 318 image-localized biopsies with spatially
matched multiparametric MRI from 74 GBM patients. The model was trained to
predict the regional genetic alteration of three GBM driver genes (EGFR,
PDGFRA, and PTEN) based on features extracted from the corresponding region of
five MRI contrast images. For comparison, a variety of existing ML algorithms
were also applied. The classification accuracy of each gene was compared
between the different algorithms. The SHapley Additive exPlanations (SHAP)
method was further applied to compute contribution scores of different contrast
images. Finally, the trained WSO-SVM was used to generate prediction maps
within the tumoral area of each patient to help visualize the intra-tumoral
genetic heterogeneity. This study demonstrated the feasibility of using MRI and
WSO-SVM to enable non-invasive prediction of intra-tumoral regional genetic
alteration for each GBM patient, which can inform future adaptive therapies for
individualized oncology.Comment: 36 pages, 8 figures, 3 table
Identification of clusters of investors from their real trading activity in a financial market
We use statistically validated networks, a recently introduced method to
validate links in a bipartite system, to identify clusters of investors trading
in a financial market. Specifically, we investigate a special database allowing
to track the trading activity of individual investors of the stock Nokia. We
find that many statistically detected clusters of investors show a very high
degree of synchronization in the time when they decide to trade and in the
trading action taken. We investigate the composition of these clusters and we
find that several of them show an over-expression of specific categories of
investors.Comment: 25 pages, 5 figure
The Astropy Problem
The Astropy Project (http://astropy.org) is, in its own words, "a community
effort to develop a single core package for Astronomy in Python and foster
interoperability between Python astronomy packages." For five years this
project has been managed, written, and operated as a grassroots,
self-organized, almost entirely volunteer effort while the software is used by
the majority of the astronomical community. Despite this, the project has
always been and remains to this day effectively unfunded. Further, contributors
receive little or no formal recognition for creating and supporting what is now
critical software. This paper explores the problem in detail, outlines possible
solutions to correct this, and presents a few suggestions on how to address the
sustainability of general purpose astronomical software
SDSS-IV MaNGA IFS Galaxy Survey—Survey Design, Execution, and Initial Data Quality
The MaNGA Survey (Mapping Nearby Galaxies at Apache Point Observatory) is one of three core programs in the Sloan Digital Sky Survey IV. It is obtaining integral field spectroscopy for 10,000 nearby galaxies at a spectral resolution of R ~ 2000 from 3622 to 10354 Å. The design of the survey is driven by a set of science requirements on the precision of estimates of the following properties: star formation rate surface density, gas metallicity, stellar population age, metallicity, and abundance ratio, and their gradients; stellar and gas kinematics; and enclosed gravitational mass as a function of radius. We describe how these science requirements set the depth of the observations and dictate sample selection. The majority of targeted galaxies are selected to ensure uniform spatial coverage in units of effective radius (Re) while maximizing spatial resolution. About two-thirds of the sample is covered out to 1.5Re (Primary sample), and one-third of the sample is covered to 2.5Re (Secondary sample). We describe the survey execution with details that would be useful in the design of similar future surveys. We also present statistics on the achieved data quality, specifically the point-spread function, sampling uniformity, spectral resolution, sky subtraction, and flux calibration. For our Primary sample, the median r-band signal-to-noise ratio is ~70 per 1.4 Å pixel for spectra stacked between 1R e and 1.5Re. Measurements of various galaxy properties from the first-year data show that we are meeting or exceeding the defined requirements for the majority of our science goals
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in
operation since July 2014. This paper describes the second data release from
this phase, and the fourteenth from SDSS overall (making this, Data Release
Fourteen or DR14). This release makes public data taken by SDSS-IV in its first
two years of operation (July 2014-2016). Like all previous SDSS releases, DR14
is cumulative, including the most recent reductions and calibrations of all
data taken by SDSS since the first phase began operations in 2000. New in DR14
is the first public release of data from the extended Baryon Oscillation
Spectroscopic Survey (eBOSS); the first data from the second phase of the
Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2),
including stellar parameter estimates from an innovative data driven machine
learning algorithm known as "The Cannon"; and almost twice as many data cubes
from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous
release (N = 2812 in total). This paper describes the location and format of
the publicly available data from SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken (both
targeting and observation details) and processed for scientific use. The SDSS
website (www.sdss.org) has been updated for this release, and provides links to
data downloads, as well as tutorials and examples of data use. SDSS-IV is
planning to continue to collect astronomical data until 2020, and will be
followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14
happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov
2017 (this is the "post-print" and "post-proofs" version; minor corrections
only from v1, and most of errors found in proofs corrected
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