94 research outputs found
The Global Genome Biodiversity Network (GGBN) Data Standard specification
© The Author(s) 2016. Published by Oxford University Press. Page 1 of 11 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. The article attached is the publisher's pdf
13[C]-Urea Breath Test as a Novel Point-of-Care Biomarker for Tuberculosis Treatment and Diagnosis
BACKGROUND: Pathogen-specific metabolic pathways may be detected by breath tests based on introduction of stable isotopically-labeled substrates and detection of labeled products in exhaled breath using portable infrared spectrometers. METHODOLOGY/PRINCIPAL FINDINGS: We tested whether mycobacterial urease activity could be utilized in such a breath test format as the basis of a novel biomarker and diagnostic for pulmonary TB. Sensitized New-Zealand White Rabbits underwent bronchoscopic infection with either Mycobacterium bovis or Mycobacterium tuberculosis. Rabbits were treated with 25 mg/kg of isoniazid (INH) approximately 2 months after infection when significant cavitary lung pathology was present. [(13)C] urea was instilled directly into the lungs of intubated rabbits at selected time points, exhaled air samples analyzed, and the kinetics of delta(13)CO(2) formation were determined. Samples obtained prior to inoculation served as control samples for background (13)CO(2) conversion in the rabbit model. (13)CO(2), from metabolic conversion of [(13)C]-urea by mycobacterial urease activity, was readily detectable in the exhaled breath of infected rabbits within 15 minutes of administration. Analyses showed a rapid increase in the rate of (13)CO(2) formation both early in disease and prior to treatment with INH. Following INH treatment, all evaluable rabbits showed a decrease in the rate of (13)CO(2) formation. CONCLUSIONS/SIGNIFICANCE: Urea breath testing may provide a useful diagnostic and biomarker assay for tuberculosis and for treatment response. Future work will test specificity for M. tuberculosis using lung-targeted dry powder inhalation formulations, combined with co-administering oral urease inhibitors together with a saturating oral dose of unlabeled urea, which would prevent the delta(13)CO(2) signal from urease-positive gastrointestinal organisms
Event-by-event correlations between () hyperon global polarization and handedness with charged hadron azimuthal separation in Au+Au collisions at from STAR
Global polarizations () of () hyperons have been
observed in non-central heavy-ion collisions. The strong magnetic field
primarily created by the spectator protons in such collisions would split the
and global polarizations (). Additionally, quantum chromodynamics (QCD) predicts
topological charge fluctuations in vacuum, resulting in a chirality imbalance
or parity violation in a local domain. This would give rise to an imbalance
() between left- and right-handed
() as well as a charge separation along the magnetic field,
referred to as the chiral magnetic effect (CME). This charge separation can be
characterized by the parity-even azimuthal correlator () and
parity-odd azimuthal harmonic observable (). Measurements of
, , and have not led to definitive
conclusions concerning the CME or the magnetic field, and has not
been measured previously. Correlations among these observables may reveal new
insights. This paper reports measurements of correlation between and
, which is sensitive to chirality fluctuations, and correlation
between and sensitive to magnetic field in Au+Au
collisions at 27 GeV. For both measurements, no correlations have been observed
beyond statistical fluctuations.Comment: 10 pages, 10 figures; paper from the STAR Collaboratio
Hyperon polarization along the beam direction relative to the second and third harmonic event planes in isobar collisions at = 200 GeV
The polarization of and hyperons along the beam
direction has been measured relative to the second and third harmonic event
planes in isobar Ru+Ru and Zr+Zr collisions at = 200 GeV. This
is the first experimental evidence of the hyperon polarization by the
triangular flow originating from the initial density fluctuations. The
amplitudes of the sine modulation for the second and third harmonic results are
comparable in magnitude, increase from central to peripheral collisions, and
show a mild dependence. The azimuthal angle dependence of the
polarization follows the vorticity pattern expected due to elliptic and
triangular anisotropic flow, and qualitatively disagree with most hydrodynamic
model calculations based on thermal vorticity and shear induced contributions.
The model results based on one of existing implementations of the shear
contribution lead to a correct azimuthal angle dependence, but predict
centrality and dependence that still disagree with experimental
measurements. Thus, our results provide stringent constraints on the thermal
vorticity and shear-induced contributions to hyperon polarization. Comparison
to previous measurements at RHIC and the LHC for the second-order harmonic
results shows little dependence on the collision system size and collision
energy.Comment: 6 pages, 5 figures, Published in Physical Review Letter
Observation of the electromagnetic field effect via charge-dependent directed flow in heavy-ion collisions at the Relativistic Heavy Ion Collider
The deconfined quark-gluon plasma (QGP) created in relativistic heavy-ion
collisions enables the exploration of the fundamental properties of matter
under extreme conditions. Non-central collisions can produce strong magnetic
fields on the order of Gauss, which offers a probe into the
electrical conductivity of the QGP. In particular, quarks and anti-quarks carry
opposite charges and receive contrary electromagnetic forces that alter their
momenta. This phenomenon can be manifested in the collective motion of
final-state particles, specifically in the rapidity-odd directed flow, denoted
as . Here we present the charge-dependent measurements of
near midrapidities for , , and
in Au+Au and isobar (Ru+Ru and
Zr+Zr) collisions at 200 GeV, and
in Au+Au collisions at 27 GeV, recorded by the STAR detector at the
Relativistic Heavy Ion Collider. The combined dependence of the signal on
collision system, particle species, and collision centrality can be
qualitatively and semi-quantitatively understood as several effects on
constituent quarks. While the results in central events can be explained by the
and quarks transported from initial-state nuclei, those in peripheral
events reveal the impacts of the electromagnetic field on the QGP. Our data put
valuable constraints on the electrical conductivity of the QGP in theoretical
calculations
Search for the chiral magnetic effect via charge-dependent azimuthal correlations relative to spectator and participant planes in Au+Au collisions at = 200 GeV
The chiral magnetic effect (CME) refers to charge separation along a strong
magnetic field due to imbalanced chirality of quarks in local parity and
charge-parity violating domains in quantum chromodynamics. The experimental
measurement of the charge separation is made difficult by the presence of a
major background from elliptic azimuthal anisotropy. This background and the
CME signal have different sensitivities to the spectator and participant
planes, and could thus be determined by measurements with respect to these
planes. We report such measurements in Au+Au collisions at a nucleon-nucleon
center-of-mass energy of 200 GeV at the Relativistic Heavy-Ion Collider. It is
found that the charge separation, with the flow background removed, is
consistent with zero in peripheral (large impact parameter) collisions. Some
indication of finite CME signals is seen with a significance of 1--3 standard
deviations in mid-central (intermediate impact parameter) collisions.
Significant residual background effects may, however, still be present.Comment: 8 pages, 3 figure
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