413 research outputs found
Microalbuminuria associated with indicators of inflammatory activity in an HIV-positive population
Background. The survival of human immunodeficiency virus (HIV)-infected patients has increased significantly since the introduction of combination antiretroviral therapy, leading to the development of important long-term complications including cardiovascular disease (CVD) and renal disease. Microalbuminuria, an indicator of glomerular injury, is associated with an increased risk of progressive renal deterioration, CVD and mortality. However, the prevalence of microalbuminuria has barely been investigated in HIV-infected individuals
Magnetic susceptibility, exchange interactions and spin-wave spectra in the local spin density approximation
Starting from exact expression for the dynamical spin susceptibility in the
time-dependent density functional theory a controversial issue about exchange
interaction parameters and spin-wave excitation spectra of itinerant electron
ferromagnets is reconsidered. It is shown that the original expressions for
exchange integrals based on the magnetic force theorem (J. Phys. F14 L125
(1984)) are optimal for the calculations of the magnon spectrum whereas static
response function is better described by the ``renormalized'' magnetic force
theorem by P. Bruno (Phys. Rev. Lett. 90, 087205 (2003)). This conclusion is
confirmed by the {\it ab initio} calculations for Fe and Ni.Comment: 12 pages, 2 figures, submitted to JPC
INK JET PROCESSING OF METALLIC NANOPARTICLE SUSPENSIONS FOR ELECTRONIC CIRCUITRY FABRICATION
ABSTRACT A novel approach in creating circuit electrodes with features as fine as 100 µm is demonstrated using a single 38 µm diameter orifice, piezoelectrically driven print head to deposit metallic nanoparticle suspensions. The suspensions consist of gold particles of ~20 nm diameter suspended in toluene solvent. The amount of gold nanoparticles present in the suspension is 30% wt. Inductor and capacitor electrode patterns are deposited onto a glass substrate and thermally processed at 300°C for 15 minutes to drive off the solvent and allow the nanoparticles to sinter, thereby yielding a conductive path with a resistivity of O(10 -7 ) Ω m
Magnetic properties of the three-dimensional Hubbard model at half filling
We study the magnetic properties of the 3d Hubbard model at half-filling in
the TPSC formalism, previously developed for the 2d model. We focus on the
N\'eel transition approached from the disordered side and on the paramagnetic
phase. We find a very good quantitative agreement with Dynamical Mean-Field
results for the isotropic 3d model. Calculations on finite size lattices also
provide satisfactory comparisons with Monte Carlo results up to the
intermediate coupling regime. We point out a qualitative difference between the
isotropic 3d case, and the 2d or anisotropic 3d cases for the double occupation
factor. Even for this local correlation function, 2d or anisotropic 3d cases
are out of reach of DMF: this comes from the inability of DMF to account for
antiferromagnetic fluctuations, which are crucial.Comment: RevTex, 9 pages +10 figure
Disorder-enhanced delocalization and local-moment quenching in a disordered antiferromagnet
The interplay of disorder and spin-fluctuation effects in a disordered
antiferromagnet is studied. In the weak-disorder regime (W \le U), while the
energy gap decreases rapidly with disorder, the sublattice magnetization,
including quantum corrections, is found to remain essentially unchanged in the
strong correlation limit. Magnon energies and Neel temperature are enhanced by
disorder in this limit. A single paradigm of disorder-enhanced delocalization
qualitatively accounts for all these weak disorder effects. Vertex corrections
and magnon damping, which appear only at order (W/U)^4, are also studied. With
increasing disorder a crossover is found at W \sim U, characterized by a rapid
decrease in sublattice magnetization due to quenching of local moments, and
formation of spin vacancies. The latter suggests a spin-dilution behavior,
which is indeed observed in softened magnon modes, lowering of Neel
temperature, and enhanced transverse spin fluctuations.Comment: 12 pages, includes 8 postscript figures. To appear in Physical Review
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Prevalence of Kidney Disease in HIV-Infected and Uninfected Rwandan Women
Background: In the United States, HIV-related kidney disease disproportionately affects individuals of African descent; however, there are few estimates of kidney disease prevalence in Africa. We evaluated the prevalence of kidney disease among HIV-infected and uninfected Rwandan women. Methods: The Rwandan Women's Interassociation Study and Assessment prospectively enrolled 936 women. Associations with estimated glomerular filtration rate (eGFR)<60 mL/min/1.73 m and proteinuria were assessed in separate logistic regression models. Results: Among 891 non-pregnant women with available data, 2.4% had an eGFR<60 mL/min/1.73 m (calculated by the Modification of Diet in Renal Disease equation, MDRD eGFR) and 8.7% had proteinuria 1+. The prevalence of decreased eGFR varied markedly depending on the estimating method used, with the highest prevalence by Cockcroft-Gault. Regardless of the method used to estimate GFR, the proportion with decreased eGFR or proteinuria did not differ significantly between HIV-infected and -uninfected women in unadjusted analysis. After adjusting for age and blood pressure, HIV infection was associated with significantly higher odds of decreased MDRD eGFR but not proteinuria. Conclusion: In a well-characterized cohort of Rwandan women, HIV infection was associated with decreased MDRD eGFR. The prevalence of decreased eGFR among HIV-infected women in our study was lower than that previously reported in African-Americans and in other Central and East African HIV populations, although there was substantial variability depending on the equation used to estimate GFR. Future studies are needed to optimize GFR estimates and to determine the impact of antiretroviral therapy on kidney disease in this population
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A new 14 GHz Electron-Cyclotron-Resonance Ion Source (ECRIS) for the heavy ion accelerator facility ATLAS
A 14 GHz Electron-Cyclotron-Resonance Ion Source (ECRIS) has been designed and built at Argonne National Laboratory. The source is a modification of the AECR at Berkeley and incorporates the latest results from ECR developments to produce intense beams of highly charged ions, including an improved magnetic confinement of the plasma electrons with an axial mirror ratio of 3.5. The aluminum plasma chamber and extraction electrode as well as a biased disk on axis at the microwave injection side donates additional electrons to the plasma, making use of the large secondary electron yield from aluminum oxide. The source is capable of ECR plasma heating using two different frequencies simultaneously to increase the electron energy gain for the production of high charge states. The main design goal is to produce several e{mu}A of at least {sup 238}U{sup 35+} in order to accelerate the beam to coulomb-barrier energies without further stripping. First charge state distributions for gaseous elements have been measured and 210 e{mu}A {sup 16}O{sup 7+} has been achieved. A normalized 90% emittance from 0.1 to 0.2 {pi} mm{sm_bullet}mrad for krypton and oxygen beam has been found
Symmetry breaking in the Hubbard model at weak coupling
The phase diagram of the Hubbard model is studied at weak coupling in two and
three spatial dimensions. It is shown that the Neel temperature and the order
parameter in d=3 are smaller than the Hartree-Fock predictions by a factor of
q=0.2599. For d=2 we show that the self-consistent (sc) perturbation series
bears no relevance to the behavior of the exact solution of the Hubbard model
in the symmetry-broken phase. We also investigate an anisotropic model and show
that the coupling between planes is essential for the validity of
mean-field-type order parameters
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A new 14 GHz electron-cyclotron-resonance ion source (ECRIS) for the heavy ion accelerator facility ATLAS: a status report
A new 14 GHz ECRIS has been designed and built over the last 2 years. The source, a modification of the Berkeley AECR, incorporates the latest results from ECR developments to produce intense beams of highly charged ions, i.e., an improved electron confinement with an axial magnetic mirror ratio of 3.5 and a radial magnetic field inside the plasma chamber of 1.0 T. The aluminium plasma chamber and extraction electrode as well as a biased disk on axis at the microwave injection side donate additional electrons to the plasma, making use of the large secondary electron yield from Al oxide. Slots in the plasma chamber allow for radial pumping which increases the AECR performance. The source will also be capable of additional ECR plasma heating using two frequencies simultaneously to increase the electron energy gain for producing high charge states. To be able to deliver usable intensities of the heaviest ion beams, the design will also allow for axial access for metal evaporation ovens and solid material samples using plasma sputtering. Main design goal is to produce several e{mu}A of U{sup 34+} in order to obtain Coulomb- barrier energies from ATLAS without further stripping
Association between high-dose erythropoiesis-stimulating agents, inflammatory biomarkers, and soluble erythropoietin receptors
<p>Abstract</p> <p>Background</p> <p>High-dose erythropoiesis-stimulating agents (ESA) for anemia of chronic kidney disease (CKD) have been associated with adverse clinical outcomes and do not always improve erythropoiesis. We hypothesized that high-dose ESA requirement would be associated with elevated inflammatory biomarkers, decreased adipokines, and increased circulating, endogenous soluble erythropoietin receptors (sEpoR).</p> <p>Methods</p> <p>A cross-sectional cohort of anemic 32 CKD participants receiving ESA were enrolled at a single center and cytokine profiles, adipokines, and sEpoR were compared between participants stratified by ESA dose requirement (usual-dose darbepoetin-α (< 1 μg/kg/week) and high-dose (≥1 μg/kg/week)).</p> <p>Results</p> <p>Baseline characteristics were similar between groups; however, hemoglobin was lower among participants on high-dose (1.4 μg/kg/week) vs usual-dose (0.5 μg/kg/week) ESA.</p> <p>In adjusted analyses, high-dose ESA was associated with an increased odds for elevations in c-reactive protein and interleukin-6 (p < 0.05 for both). There was no correlation between high-dose ESA and adipokines. Higher ESA dose correlated with higher levels of sEpoR (r<sub>s </sub>= 0.39, p = 0.03). In adjusted analyses, higher ESA dose (per μcg/kg/week) was associated with a 53% greater odds of sEpoR being above the median (p < 0.05).</p> <p>Conclusion</p> <p>High-dose ESA requirement among anemic CKD participants was associated with elevated inflammatory biomarkers and higher levels of circulating sEpoR, an inhibitor of erythropoiesis. Further research confirming these findings is warranted.</p> <p>Trial registration</p> <p>Clinicaltrials.gov <a href="http://www.clinicaltrials.gov/ct2/show/NCT00526747">NCT00526747</a></p
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