1,679 research outputs found
Atrial fibrillation impairs the diagnostic performance of cardiac natriuretic peptides in dyspneic patients. results from the BACH Study (Biomarkers in ACute Heart Failure)
Objectives: The purpose of this study was to assess the impact of atrial fibrillation (AF) on the performance of mid-region amino terminal pro-atrial natriuretic peptide (MR-proANP) in comparison with the B-type peptides (BNP and NT-proBNP) for diagnosis of acute heart failure (HF) in dyspneic patients. Background: The effects of AF on the diagnostic and prognostic performance of MR-proANP in comparison with the B type natriuretic peptides have not been previously reported. Methods: A total of 1,445 patients attending the emergency department with acute dyspnea had measurements taken of MR-proANP, BNP, and NT-proBNP values on enrollment to the BACH trial and were grouped according to presence or absence of AF and HF. Results: AF was present in 242 patients. Plasma concentrations of all three peptides were lowest in those with neither AF nor HF and AF without HF was associated with markedly increased levels (p < 0.00001). HF with or without AF was associated with a significant further increment (p < 0.00001 for all three markers). Areas under receiver operator characteristic curves (AUCs) for discrimination of acute HF were similar and powerful for all peptides without AF (0.893 to 0.912; all p < 0.001) with substantial and similar reductions (0.701 to 0.757) in the presence of AF. All 3 peptides were independently prognostic but there was no interaction between any peptide and AF for prediction of all-cause mortality. Conclusions: AF is associated with increased plasma natriuretic peptide (MR-proANP, BNP and NT-proBNP) levels in the absence of HF. The diagnostic performance of all three peptides is impaired by AF. This warrants consideration of adjusted peptide thresholds for diagnostic use in AF and mandates the continued search for markers free of confounding by AF
Achieving enhanced gain in photorefractive polymers by eliminating electron contributions using large bias fields
Photorefractive polymers have been extensively studied for over two decades and have found applications in holographic displays and optical image processing. The complexity of these materials arises from multiple charge contributions, for example, leading to the formation of competing photorefractive gratings. It has been recently shown that in a photorefractive polymer at relatively moderate applied electric fields the primary charge carriers (holes) establish an initial grating, followed by a subsequent competing grating (electrons) resulting in a decreased two-beam coupling and diffraction efficiencies. In this paper, it is shown that with relatively large sustainable bias fields, the two-beam coupling efficiency is enhanced owing to a decreased electron contribution. These results also explain the cause of dielectric breakdown experienced under large bias fields. Our conclusions are supported by self-pumped transient two-beam coupling and photocurrent measurements as a function of applied bias fields at different wavelengths
Semiclassical Extremal Blackholes
Extremal black holes are studied in a two dimensional model motivated by a
dimensional reduction from four dimensions. Their quantum corrected geometry is
calculated semiclassically and a mild singularity is shown to appear at the
horizon.
Extensions of the geometry past the horizon are not unique but there are
continuations free from malevolent singularities. A few comments are made about
the relevance of these results to four dimensions and to the study of black
hole entropy and information loss.Comment: 16 pages, 2 figures upon request, CALT-68-1833 - (new version
corrects omissions in previous list of references
Geometry dominated fluid adsorption on sculptured substrates
Experimental methods allow the shape and chemical composition of solid
surfaces to be controlled at a mesoscopic level. Exposing such structured
substrates to a gas close to coexistence with its liquid can produce quite
distinct adsorption characteristics compared to that occuring for planar
systems, which may well play an important role in developing technologies such
as super-repellent surfaces or micro-fluidics. Recent studies have concentrated
on adsorption of liquids at rough and heterogeneous substrates and the
characterisation of nanoscopic liquid films. However, the fundamental effect of
geometry has hardly been addressed. Here we show that varying the shape of the
substrate can exert a profound influence on the adsorption isotherms allowing
us to smoothly connect wetting and capillary condensation through a number of
novel and distinct examples of fluid interfacial phenomena. This opens the
possibility of tailoring the adsorption properties of solid substrates by
sculpturing their surface shape.Comment: 6 pages, 4 figure
Language and cultural capital in school experience of Polish children in Scotland
This article addresses the complex relationship between migration and education in the context of recent intra-European labour mobility. It considers how this mobility impacts the education and life chances of migrant students attending schools in Scotland, UK. By examining the experiences of Polish migrant children and youth at schools in Scotland, the article engages with the issues of language, cultural capital transferability and social positioning. Drawing on qualitative data from 65 in-depth interviews with school children aged 5–17 years, their parents and teachers, as well as observations in the contexts of school and home, the article points to a range of factors affecting the transition of migrant pupils to new schools and social environments
Irreversible Quantum Mechanics in the Neutral K-System
The neutral Kaon system is used to test the quantum theory of resonance
scattering and decay phenomena. The two dimensional Lee-Oehme-Yang theory with
complex Hamiltonian is obtained by truncating the complex basis vector
expansion of the exact theory in Rigged Hilbert space. This can be done for K_1
and K_2 as well as for K_S and K_L, depending upon whether one chooses the
(self-adjoint, semi-bounded) Hamiltonian as commuting or non-commuting with CP.
As an unexpected curiosity one can show that the exact theory (without
truncation) predicts long-time 2 pion decays of the neutral Kaon system even if
the Hamiltonian conserves CP.Comment: 36 pages, 1 PostScript figure include
Time invariance violating nuclear electric octupole moments
The existence of a nuclear electric octupole moment (EOM) requires both
parity and time invariance violation. The EOMs of odd nuclei that are
induced by a particular T- and P-odd interaction are calculated. We compare
such octupole moments with the collective EOMs that can occur in nuclei having
a static octupole deformation. A nuclear EOM can induce a parity and time
invariance violating atomic electric dipole moment, and the magnitude of this
effect is calculated. The contribution of a nuclear EOM to such a dipole moment
is found, in most cases, to be smaller than that of other mechanisms of atomic
electric dipole moment production.Comment: Uses RevTex, 25 page
Aging in humid granular media
Aging behavior is an important effect in the friction properties of solid
surfaces. In this paper we investigate the temporal evolution of the static
properties of a granular medium by studying the aging over time of the maximum
stability angle of submillimetric glass beads. We report the effect of several
parameters on these aging properties, such as the wear on the beads, the stress
during the resting period, and the humidity content of the atmosphere. Aging
effects in an ethanol atmosphere are also studied. These experimental results
are discussed at the end of the paper.Comment: 7 pages, 9 figure
Comparison of Meat Composition from Offspring of Cloned and Conventionally Produced Boars
This study compares the meat composition of the offspring from boars produced by somatic cell nuclear transfer (n = 4) to that of the offspring from conventionally produced boars (n = 3). In total, 89 commercial gilts were artificially inseminated and 61 progressed to term and farrowed. All of the resulting piglets were housed and raised identically under standard commercial settings and slaughtered upon reaching market weight. Loin samples were taken from each slaughtered animal and shipped offsite for meat composition analysis. In total, loin samples from 404 animals (242 from offspring of clones and 162 from controls) were analyzed for 58 different parameters generating 14,036 and 9396 data points from offspring of clones and the controls, respectively. Values for controls were used to establish a range for each parameter. Ten percent was then added to the maximum and subtracted from the minimum of the control range, and all results within this range were considered clinically irrelevant. Of the 14,036 data points from the offspring of clones, only three points were found outside the clinically irrelevant range, two of which were within the range established by the USDA National Nutrient Database for Standard Reference, Release 18, 2005. The only outlier was the presence of Eicosadienoic acid (C20:2) in one sample which is typically present in minute quantities in pork; no reference data were found regarding this fatty acid in the USDA National Nutrient Database. In conclusion, these data indicated that meat from the offspring of clones was not chemically different than meat from controls and therefore supported the case for the safety of meat from the offspring of clones
Performance of two Askaryan Radio Array stations and first results in the search for ultra-high energy neutrinos
Ultra-high energy neutrinos are interesting messenger particles since, if
detected, they can transmit exclusive information about ultra-high energy
processes in the Universe. These particles, with energies above
, interact very rarely. Therefore, detectors that
instrument several gigatons of matter are needed to discover them. The ARA
detector is currently being constructed at South Pole. It is designed to use
the Askaryan effect, the emission of radio waves from neutrino-induced cascades
in the South Pole ice, to detect neutrino interactions at very high energies.
With antennas distributed among 37 widely-separated stations in the ice, such
interactions can be observed in a volume of several hundred cubic kilometers.
Currently 3 deep ARA stations are deployed in the ice of which two have been
taking data since the beginning of the year 2013. In this publication, the ARA
detector "as-built" and calibrations are described. Furthermore, the data
reduction methods used to distinguish the rare radio signals from overwhelming
backgrounds of thermal and anthropogenic origin are presented. Using data from
only two stations over a short exposure time of 10 months, a neutrino flux
limit of is
calculated for a particle energy of 10^{18}eV, which offers promise for the
full ARA detector.Comment: 21 pages, 34 figures, 1 table, includes supplementary materia
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