400 research outputs found
The Search for Extragalactic Lithium Hydride
We have conducted Combined Array for Research in Millimeter-wave Astronomy
(CARMA) observations of LiH, in absorption, toward three quasars. These
quasars, B0218+357, PKS1830-211, and PKS0201+113, have redshifts of z = 0.685 -
3.387\sigma$ detection of LiH
toward B0218+357 with a column density of 1.4x10^{12} cm^{-2} and place an
upper limit on the ^6Li/^7Li ratio of <0.16. LiH was not detected toward any
other source.Comment: 18 pages, 8 figures, accepted for publication in The Astrophysical
Journa
Anisotropic Spin Hamiltonians due to Spin-Orbit and Coulomb Exchange Interactions
This paper contains the details of Phys. Rev. Lett. 73, 2919 (1994) and, to a
lesser extent, Phys. Rev. Lett. 72, 3710 (1994). We treat a Hubbard model which
includes all the 3d states of the Cu ions and the 2p states of the O ions. We
also include spin-orbit interactions, hopping between ground and excited
crystal field states of the Cu ions, and rather general Coulomb interactions.
Our analytic results for the spin Hamiltonian, H, are corroborated by numerical
evaluations of the energy splitting of the ground manifold for two holes on
either a pair of Cu ions or a Cu-O-Cu complex. In the tetragonal symmetry case
and for the model considered, we prove that H is rotationally invariant in the
absence of Coulomb exchange. When Coulomb exchange is present, each bond
Hamiltonian has full biaxial anisotropy, as expected for this symmetry. For
lower symmetry situations, the single bond spin Hamiltonian is anisotropic at
order t**6 for constant U and at order t**2 for nonconstant U. (Constant U
means that the Coulomb interaction between orbitals does not depend on which
orbitals are involved.)Comment: 50 pages, ILATEX Version 2.09 <13 Jun 1989
Physical properties of misfit-layered (Bi,Pb)-Sr-Co-O system: Effect of hole doping into triangular lattice formed by low-spin Co ions
Pb-doping effect on physical properties of misfit-layered (Bi,Pb)-Sr-Co-O
system, in which Co ions form a two-dimensional triangular lattice, was
investigated in detail by electronic transport, magnetization and specific-heat
measurements. Pb doping enhances the metallic behavior, suggesting that
carriers are doped. Pb doping also enhances the magnetic correlation in this
system and increases the magnetic transition temperature. We found the
existence of the short-range magnetic correlation far above the transition
temperature, which seems to induce the spin-glass state coexisting with the
ferromagnetic long-range order at low temperatures. Specific-heat measurement
suggests that the effective mass of the carrier in (Bi,Pb)-Sr-Co-O is not
enhanced so much as reported in NaCoO. Based on these experimental
results, we propose a two-bands model which consists of narrow and
rather broad bands. The observed magnetic property and
magnetotransport phenomena are explained well by this model
Using fractional exhaled nitric oxide (FeNO) to diagnose steroid-responsive disease and guide asthma management in routine care
Acknowledgements We thank Robin Taylor for his informative thinking and publications on FeNO, which have helped to influence and direct the thinking of the authors. Funding Extraction of the real-life dataset was funded by Research in Real Life Limited, the analysis of the dataset and the writing of this manuscript were co-funded (50:50) by Research in Real Life Limited and Aerocrine.Peer reviewedPublisher PD
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An epistatic interaction between pre-natal smoke exposure and socioeconomic status has a significant impact on bronchodilator drug response in African American youth with asthma.
Background: Asthma is one of the leading chronic illnesses among children in the United States. Asthma prevalence is higher among African Americans (11.2%) compared to European Americans (7.7%). Bronchodilator medications are part of the first-line therapy, and the rescue medication, for acute asthma symptoms. Bronchodilator drug response (BDR) varies substantially among different racial/ethnic groups. Asthma prevalence in African Americans is only 3.5% higher than that of European Americans, however, asthma mortality among African Americans is four times that of European Americans; variation in BDR may play an important role in explaining this health disparity. To improve our understanding of disparate health outcomes in complex phenotypes such as BDR, it is important to consider interactions between environmental and biological variables.
Results: We evaluated the impact of pairwise and three-variable interactions between environmental, social, and biological variables on BDR in 233 African American youth with asthma using Visualization of Statistical Epistasis Networks (ViSEN). ViSEN is a non-parametric entropy-based approach able to quantify interaction effects using an information-theory metric known as Information Gain (IG). We performed analyses in the full dataset and in sex-stratified subsets. Our analyses identified several interaction models significantly, and suggestively, associated with BDR. The strongest interaction significantly associated with BDR was a pairwise interaction between pre-natal smoke exposure and socioeconomic status (full dataset IG: 2.78%,
Conclusions: Our study identified novel interaction effects significantly, and suggestively, associated with BDR in African American children with asthma. Notably, we found that all of the interactions identified by ViSEN were pure interaction effects, in that they were not the result of strong main effects on BDR, highlighting the complexity of the network of biological and environmental factors impacting this phenotype. Several associations uncovered by ViSEN would not have been detected using regression-based methods, thus emphasizing the importance of employing statistical methods optimized to detect both additive and non-additive interaction effects when studying complex phenotypes such as BDR. The information gained in this study increases our understanding and appreciation of the complex nature of the interactions between environmental and health-related factors that influence BDR and will be invaluable to biomedical researchers designing future studies
Fermi Large Area Telescope Observations of Gamma-ray Pulsars PSR J1057-5226, J1709-4429, and J1952+3252
The Fermi Large Area Telescope (LAT) data have confirmed the pulsed emission
from all six high-confidence gamma-ray pulsars previously known from the EGRET
observations. We report results obtained from the analysis of 13 months of LAT
data for three of these pulsars (PSR J1057-5226, PSR J1709-4429, and PSR
J1952+3252) each of which had some unique feature among the EGRET pulsars. The
excellent sensitivity of LAT allows more detailed analysis of the evolution of
the pulse profile with energy and also of the variation of the spectral shape
with phase. We measure the cutoff energy of the pulsed emission from these
pulsars for the first time and provide a more complete picture of the emission
mechanism. The results confirm some, but not all, of the features seen in the
EGRET data.Comment: Accepted for publication in ApJ. 45 pages, 12 figures, 11 tables.
Corresponding authors: O. Celik, F. Gargano, T. Reposeur, D.J. Thompso
ITGB5 and AGFG1 variants are associated with severity of airway responsiveness
Background: Airway hyperresponsiveness (AHR), a primary characteristic of asthma, involves increased airway smooth muscle contractility in response to certain exposures. We sought to determine whether common genetic variants were associated with AHR severity. Methods: A genome-wide association study (GWAS) of AHR, quantified as the natural log of the dosage of methacholine causing a 20% drop in FEV1, was performed with 994 non-Hispanic white asthmatic subjects from three drug clinical trials: CAMP, CARE, and ACRN. Genotyping was performed on Affymetrix 6.0 arrays, and imputed data based on HapMap Phase 2, was used to measure the association of SNPs with AHR using a linear regression model. Replication of primary findings was attempted in 650 white subjects from DAG, and 3,354 white subjects from LHS. Evidence that the top SNPs were eQTL of their respective genes was sought using expression data available for 419 white CAMP subjects. Results: The top primary GWAS associations were in rs848788 (P-value 7.2E-07) and rs6731443 (P-value 2.5E-06), located within the ITGB5 and AGFG1 genes, respectively. The AGFG1 result replicated at a nominally significant level in one independent population (LHS P-value 0.012), and the SNP had a nominally significant unadjusted P-value (0.0067) for being an eQTL of AGFG1. Conclusions: Based on current knowledge of ITGB5 and AGFG1, our results suggest that variants within these genes may be involved in modulating AHR. Future functional studies are required to confirm that our associations represent true biologically significant findings
Comparison of the effects of salmeterol/fluticasone propionate with fluticasone propionate on airway physiology in adults with mild persistent asthma
<p>Abstract</p> <p>Background</p> <p>This study compared the effect of inhaled fluticasone propionate (FP) with the combination of salmeterol/fluticasone propionate (SFC) on lung function parameters in patients with mild asthma.</p> <p>Methods</p> <p>Adult patients with mild persistent asthma (≥ 80% predicted FEV<sub>1</sub>) receiving 200–500 μg of BDP or equivalent were randomised to receive either FP 100 μg or SFC 50/100 μg twice daily from a Diskus<sup>® </sup>inhaler for four weeks. The primary outcome was the change from baseline in airway resistance (sRaw) at 12 hrs post dose measured by whole body plethysmography. Impulse oscillometry and spirometry were also performed.</p> <p>Results</p> <p>A comparison of the geometric mean sRaw at 12 hrs post dose in the SFC group to the FP group gave a ratio of 0.76 (0.66 – 0.89, p < 0.001) at week 2 and 0.81 (0.71 – 0.94, p = 0.006) at week 4. Similarly, significant results in favour of SFC for oscillometry measurements of resistance and reactance were observed. FEV<sub>1 </sub>was also significantly superior at week 2 in the SFC group (mean difference 0.16L, 95% CI; 0.03 – 0.28, p = 0.015), but not at week 4 (mean difference 0.17L, 95% CI -0.01 – 0.34, p = 0.060).</p> <p>Conclusion</p> <p>SFC is superior to FP in reducing airway resistance in mild asthmatics with near normal FEV<sub>1 </sub>values. This study provides evidence that changes in pulmonary function in patients with mild asthma are detected more sensitively by plethysmography compared to spirometry</p> <p>Trial registration number</p> <p>NCT00370591.</p
NIOX VERO: Individualized Asthma Management in Clinical Practice
As we move toward an era of precision medicine, novel biomarkers of disease will enable the identification and personalized treatment of new endotypes. In asthma, fractional exhaled nitric oxide (FeNO) serves as a surrogate marker of airway inflammation that often correlates with the presence of sputum eosinophils. The increase in FeNO is driven by an upregulation of inducible nitric oxide synthase (iNOS) by cytokines, which are released as a result of type-2 airway inflammation. Scientific evidence supports using FeNO in routine clinical practice. In steroid-naive patients and in patients with mild asthma, FeNO levels decrease within days after corticosteroid treatment in a dose-dependent fashion and increase after steroid withdrawal. In difficult asthma, FeNO testing correlates with anti-inflammatory therapy compliance. Assessing adherence by FeNO testing can remove the confrontational aspect of questioning a patient about compliance and change the conversation to one of goal setting and ways to improve disease management. However, the most important aspect of incorporating FeNO in asthma management is the reduction in the risk of exacerbations. In a recent primary care study, reduction of exacerbation rates and improved symptom control without increasing overall inhaled corticosteroid (ICS) use were demonstrated when a FeNO-guided anti-inflammatory treatment algorithm was assessed and compared to the standard care. A truly personalized asthma management approach—showing reduction of exacerbation rates, overall use of ICS and neonatal hospitalizations—was demonstrated when FeNO testing was applied as part of the treatment algorithm that managed asthma during pregnancy. The aim of this article is to describe how FeNO and the NIOX VERO® analyzer can help to optimize diagnosis and treatment choices and to aid in the monitoring and improvement of clinical asthma outcomes in children and adults
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