561 research outputs found
Urine metabolomic analysis to detect metabolites associated with the development of contrast induced nephropathy.
ObjectiveContrast induced nephropathy (CIN) is a result of injury to the proximal tubules. The incidence of CIN is around 11% for imaging done in the acute care setting. We aim to analyze the metabolic patterns in the urine, before and after dosing with intravenous contrast for computed tomography (CT) imaging of the chest, to determine if metabolomic changes exist in patients who develop CIN.MethodsA convenience sample of high risk patients undergoing a chest CT with intravenous contrast were eligible for enrollment. Urine samples were collected prior to imaging and 4 to 6 hours post imaging. Samples underwent gas chromatography/mass spectrometry profiling. Peak metabolite values were measured and data was log transformed. Significance analysis of microarrays and partial least squares was used to determine the most significant metabolites prior to CT imaging and within subject. Analysis of variance was used to rank metabolites associated with temporal change and CIN. CIN was defined as an increase in serum creatinine level of ≥ 0.5 mg/dL or ≥ 25% above baseline within 48 hours after contrast administration.ResultsWe sampled paired urine samples from 63 subjects. The incidence of CIN was 6/63 (9.5%). Patients without CIN had elevated urinary citric acid and taurine concentrations in the pre-CT urine. Xylulose increased in the post CT sample in patients who developed CIN.ConclusionDifferences in metabolomics patterns in patients who do and do not develop CIN exist. Metabolites may be potential early identifiers of CIN and identify patients at high-risk for developing this condition prior to imaging
Universal recovery maps and approximate sufficiency of quantum relative entropy
The data processing inequality states that the quantum relative entropy
between two states and can never increase by applying the same
quantum channel to both states. This inequality can be
strengthened with a remainder term in the form of a distance between and
the closest recovered state , where
is a recovery map with the property that . We show the existence of an explicit recovery map
that is universal in the sense that it depends only on and the quantum
channel to be reversed. This result gives an alternate,
information-theoretic characterization of the conditions for approximate
quantum error correction.Comment: v3: 24 pages, 1 figure, final version published in Annales Henri
Poincar\'
OSIRIS-REx Touch-And-Go (TAG) Mission Design and Analysis
The Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission is a NASA New Frontiers mission launching in 2016 to rendezvous with the near-Earth asteroid (101955) 1999 RQ36 in late 2018. After several months in formation with and orbit about the asteroid, OSIRIS-REx will fly a Touch-And-Go (TAG) trajectory to the asteroid s surface to obtain a regolith sample. This paper describes the mission design of the TAG sequence and the propulsive maneuvers required to achieve the trajectory. This paper also shows preliminary results of orbit covariance analysis and Monte-Carlo analysis that demonstrate the ability to arrive at a targeted location on the surface of RQ36 within a 25 meter radius with 98.3% confidence
Using [C II] 158 μm Emission from Isolated ISM Phases as a Star Formation Rate Indicator
The brightest observed emission line in many star-forming galaxies is the [C II] 158 μm line, making it detectable up to z ~ 7. In order to better understand and quantify the [C II] emission as a tracer of star formation, the theoretical ratio between the [N II] 205 μm emission and the [C II] 158 μm emission has been employed to empirically determine the fraction of [C II] emission that originates from the ionized and neutral phases of the interstellar medium (ISM). Sub-kiloparsec measurements of the [C II] 158 μm and [N II] 205 μm lines in nearby galaxies have recently become available as part of the Key Insights in Nearby Galaxies: a Far Infrared Survey with Herschel (KINGFISH) and Beyond the Peak programs. With the information from these two far-infrared lines along with the multi-wavelength suite of KINGFISH data, a calibration of the [C II] emission line as a star formation rate (SFR) indicator and a better understanding of the [C II] deficit are pursued. [C II] emission is also compared to polycyclic aromatic hydrocarbon (PAH) emission in these regions to compare photoelectric heating from PAH molecules to cooling by [C II] in the neutral and ionized phases of the ISM. We find that the [C II] emission originating in the neutral phase of the ISM does not exhibit a deficit with respect to the infrared luminosity and is therefore preferred over the [C II] emission originating in the ionized phase of the ISM as an SFR indicator for the normal star-forming galaxies included in this sample
Haloes gone MAD: The Halo-Finder Comparison Project
[abridged] We present a detailed comparison of fundamental dark matter halo
properties retrieved by a substantial number of different halo finders. These
codes span a wide range of techniques including friends-of-friends (FOF),
spherical-overdensity (SO) and phase-space based algorithms. We further
introduce a robust (and publicly available) suite of test scenarios that allows
halo finder developers to compare the performance of their codes against those
presented here. This set includes mock haloes containing various levels and
distributions of substructure at a range of resolutions as well as a
cosmological simulation of the large-scale structure of the universe. All the
halo finding codes tested could successfully recover the spatial location of
our mock haloes. They further returned lists of particles (potentially)
belonging to the object that led to coinciding values for the maximum of the
circular velocity profile and the radius where it is reached. All the finders
based in configuration space struggled to recover substructure that was located
close to the centre of the host halo and the radial dependence of the mass
recovered varies from finder to finder. Those finders based in phase space
could resolve central substructure although they found difficulties in
accurately recovering its properties. Via a resolution study we found that most
of the finders could not reliably recover substructure containing fewer than
30-40 particles. However, also here the phase space finders excelled by
resolving substructure down to 10-20 particles. By comparing the halo finders
using a high resolution cosmological volume we found that they agree remarkably
well on fundamental properties of astrophysical significance (e.g. mass,
position, velocity, and peak of the rotation curve).Comment: 27 interesting pages, 20 beautiful figures, and 4 informative tables
accepted for publication in MNRAS. The high-resolution version of the paper
as well as all the test cases and analysis can be found at the web site
http://popia.ft.uam.es/HaloesGoingMA
Oxidation resistance of graphene-coated Cu and Cu/Ni alloy
The ability to protect refined metals from reactive environments is vital to
many industrial and academic applications. Current solutions, however,
typically introduce several negative effects, including increased thickness and
changes in the metal physical properties. In this paper, we demonstrate for the
first time the ability of graphene films grown by chemical vapor deposition to
protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy
from air oxidation. SEM, Raman spectroscopy, and XPS studies show that the
metal surface is well protected from oxidation even after heating at 200
\degree C in air for up to 4 hours. Our work further shows that graphene
provides effective resistance against hydrogen peroxide. This protection method
offers significant advantages and can be used on any metal that catalyzes
graphene growth
Toxigenic Clostridium difficile colonization among hospitalised adults; risk factors and impact on survival
Objectives: To establish risk factors for Clostridium difficile colonization among hospitalized patients in England.
Methods: Patients admitted to elderly medicine wards at three acute hospitals in England were recruited to a prospective observational study. Participants were asked to provide a stool sample as soon as possible after enrolment and then weekly during their hospital stay. Samples were cultured for C. difficile before ribotyping and toxin detection by PCR. A multivariable logistic regression model of risk factors for C. difficile colonization was fitted from univariable risk factors significant at the p < 0.05 level.
Results: 410/727 participants submitted ≥1 stool sample and 40 (9.8%) carried toxigenic C. difficile in the first sample taken. Ribotype 106 was identified three times and seven other ribotypes twice. No ribotype 027 strains were identified. Independent predictors of colonization were previous C. difficile infection (OR 4.53 (95% C.I. 1.33–15.48) and malnutrition (MUST score ≥2) (OR 3.29 (95% C.I. 1.47–7.35)). Although C. difficile colonised patients experienced higher 90-day mortality, colonization was not an independent risk for death.
Conclusions: In a non-epidemic setting patients who have previously had CDI and have a MUST score of ≥2 are at increased risk of C. difficile colonization and could be targeted for active surveillance to prevent C. difficile transmission
Decision-making of English Netball Superleague umpires: Contextual and dispositional influences
Objectives. The decisions made by officials have a direct bearing on the outcomes of competitive sport contests. In an exploratory study, we examine the interrelationships between the decisions made by elite netball umpires, the potential contextual and environmental influences (e.g., crowd size), and the umpires’ dispositional tendencies – specifically, their propensity to deliberate and ruminate on their decisions.
Design/Method. Filmed footage from 60 England Netball Superleague matches was coded using performance analysis software. We measured the number of decisions made overall, and for home and away teams; league position; competition round; match quarter; and crowd size. Additionally, 10 umpires who officiated in the matches completed the Decision-Specific Reinvestment Scale (DSRS).
Results. Regression analyses predicted that as home teams’ league position improved the number of decisions against away teams increased. A model comprising competition round and average league position of both teams predicted the number of decisions made in matches, but neither variable emerged as a significant predictor. The umpire analyses revealed that greater crowd size was associated with an increase in decisions against away teams. The Decision Rumination factor was strongly negatively related to the number of decisions in Quarters 1 and 3, this relationship was driven by fewer decisions against home teams by umpires who exhibited higher Rumination subscale scores.
Conclusions. These findings strengthen our understanding of contextual, environmental, and dispositional influences on umpires’ decision-making behaviour. The tendency to ruminate upon decisions may explain the changes in decision behaviour in relation to the home team advantage effect
Universal recoverability in quantum information
The quantum relative entropy is well known to obey a monotonicity property (i.e., it does not increase under the action of a quantum channel). Here we present several refinements of this entropy inequality, some of which have a physical interpretation in terms of recovery from the action of the channel. The recovery channel given here is explicit and universal, depending only on the channel and one of the arguments to the relative entropy
Haloes gone MAD: The Halo-Finder Comparison Project
We present a detailed comparison of fundamental dark matter halo properties retrieved by a substantial number of different halo finders. These codes span a wide range of techniques including friends-of-friends, spherical-overdensity and phase-space-based algorithms. We further introduce a robust (and publicly available) suite of test scenarios that allow halo finder developers to compare the performance of their codes against those presented here. This set includes mock haloes containing various levels and distributions of substructure at a range of resolutions as well as a cosmological simulation of the large-scale structure of the universe. All the halo-finding codes tested could successfully recover the spatial location of our mock haloes. They further returned lists of particles (potentially) belonging to the object that led to coinciding values for the maximum of the circular velocity profile and the radius where it is reached. All the finders based in configuration space struggled to recover substructure that was located close to the centre of the host halo, and the radial dependence of the mass recovered varies from finder to finder. Those finders based in phase space could resolve central substructure although they found difficulties in accurately recovering its properties. Through a resolution study we found that most of the finders could not reliably recover substructure containing fewer than 30-40 particles. However, also here the phase-space finders excelled by resolving substructure down to 10-20 particles. By comparing the halo finders using a high-resolution cosmological volume, we found that they agree remarkably well on fundamental properties of astrophysical significance (e.g. mass, position, velocity and peak of the rotation curve). We further suggest to utilize the peak of the rotation curve, vmax, as a proxy for mass, given the arbitrariness in defining a proper halo edg
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