Collective excitation spectrum of a disordered Hubbard model

We study the collective excitation spectrum of a d=3 site-disordered Anderson-Hubbard model at half-filling, via a random-phase approximation (RPA) about broken-symmetry, inhomogeneous unrestricted Hartree-Fock (UHF) ground states. We focus in particular on the density and character of low-frequency collective excitations in the transverse spin channel. In the absence of disorder, these are found to be spin-wave-like for all but very weak interaction strengths, extending down to zero frequency and separated from a Stoner-like band, to which there is a gap. With disorder present, a prominent spin-wave-like band is found to persist over a wide region of the disorder-interaction phase plane in which the mean-field ground state is a disordered antiferromagnet, despite the closure of the UHF single-particle gap. Site resolution of the RPA excitations leads to a microscopic rationalization of the evolution of the spectrum with disorder and interaction strength, and enables the observed localization properties to be interpreted in terms of the fraction of strong local moments and their site-differential distribution.Comment: 25 pages (revtex), 9 postscript figure

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

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 B. References adde

Antiretroviral Therapy, Renal Function among HIV-Infected Tanzanian, Adults, HIV/AIDS, .

Data regarding the outcomes of HIV-infected adults with baseline renal dysfunction who start antiretroviral therapy are conflicting. We followed up a previously-published cohort of HIV-infected adult outpatients in northwest Tanzania who had high prevalence of renal dysfunction at the time of starting antiretroviral therapy (between November 2009 and February 2010). Patients had serum creatinine, proteinuria, microalbuminuria, and CD4(+) T-cell count measured at the time of antiretroviral therapy initiation and at follow-up. We used the adjusted Cockroft-Gault equation to calculate estimated glomerular filtration rates (eGFRs). In this cohort of 171 adults who had taken antiretroviral therapy for a median of two years, the prevalence of renal dysfunction (eGFR <90 mL/min/1.73 m(2)) decreased from 131/171 (76.6%) at the time of ART initiation to 50/171 (29.2%) at the time of follow-up (p<0.001). Moderate dysfunction (eGFR<60 mL/min/1.73 m(2)) decreased from 21.1% at antiretroviral therapy initiation to 1.1% at follow-up (p<0.001), as did the prevalence of microalbuminuria (72% to 44%, p<0.001). Use of tenofovir was not associated with renal dysfunction at follow-up. Mild and moderate renal dysfunction were common in this cohort of HIV-infected adults initiating antiretroviral therapy, and both significantly improved after a median follow-up time of 2 years. Our work supports the renal safety of antiretroviral therapy in African adults with mild-moderate renal dysfunction, suggesting that these regimens do not lead to renal damage in the majority of patients and that they may even improve renal function in patients with mild to moderate renal dysfunction

Proteinuria, CrCl, and Immune Activation in Antiretroviral-Naïve HIV-Infected Subjects

Because both renal disease and immune activation predict progression to AIDS, we evaluated the relationships between dipstick proteinuria ≥1+ [7% of 1012 subjects], CrCl <90mL/min [18% of 1071 subjects], and percentages of peripheral activated CD8 cells (CD8+CD38+HLA-DR+) in antiretroviral-naïve, HIV-infected subjects enrolled into AIDS Clinical Trials Group studies 384 and A5095. Proteinuria, but not CrCl, was associated with higher percentages of CD8+CD38+HLA-DR+ cells [55% vs. 50%; P=0.01], with even more pronounced differences in men and among Blacks and Hispanics. Proteinuria may be a surrogate measure of greater immune activation in HIV-infected patients initiating antiretroviral therapy

Species diversity of Trichoderma in Poland

In the present study, we reinvestigate the diversity of Trichoderma in Poland utilizing a combination of morphological and molecular/phylogenetic methods. A total of 170 isolates were collected from six different substrata at 49 sites in Poland. These were divided among 14 taxa as follows: 110 of 170 Trichoderma isolates were identified to the species level by the analysis of their ITS1, ITS2 rDNA sequences as: T. harzianum (43 isolates), T. aggressivum (35), T. citrinoviride (11), T. hamatum (9), T. virens (6), T. longibrachiatum (4), T. polysporum (1), and T. tomentosum (1); 60 isolates belonging to the Viride clade were identified based on a fragment of the translation-elongation factor 1-alpha (tef1) gene as: T. atroviride (20 isolates), T. gamsii (2), T. koningii (17), T. viridescens (13), T. viride (7), and T. koningiopsis (1). Identifications were made using the BLAST interface in TrichOKEY and TrichoBLAST (http://www.isth.info). The most diverse substrata were soil (nine species per 22 isolates) and decaying wood (nine species per 75 isolates). The most abundant species (25%) isolated from all substrata was T. harzianum

Renal function at the time of a myocardial infarction maintains prognostic value for more than 10 years

<p>Abstract</p> <p>Background</p> <p>Renal function is an important predictor of mortality in patients with myocardial infarction (MI), but changes in the impact over time have not been well described.</p> <p>We examined the importance of renal function by estimated GFR (eGFR) and se-creatinine as an independent long-term prognostic factor.</p> <p>Methods</p> <p>Prospective follow-up of 6653 consecutive MI patients screened for entry in the Trandolapril Cardiac Evaluation (TRACE) study. The patients were analysed by Kaplan-Meier survival analysis, landmark analysis and Cox proportional hazard models. Outcome measure was all-cause mortality.</p> <p>Results</p> <p>An eGFR below 60 ml per minute per 1.73 m², consistent with chronic renal disease, was present in 42% of the patients. We divided the patients into 4 groups according to eGFR. Overall, Cox proportional-hazards models showed that eGFR was a significant prognostic factor in the two groups with the lowest eGFR, hazard ratio 1,72 (confidence interval (CI) 1,56-1,91) in the group with the lowest eGFR. Using the eGFR group with normal renal function as reference, we observed an incremental rise in hazard ratio. We divided the follow-up period in 2-year intervals. Landmark analysis showed that eGFR at the time of screening continued to show prognostic effect until 16 years of follow-up. By multivariable Cox regression analysis, the prognostic effect of eGFR persisted for 12 years and of se-creatinine for 10 years. When comparing the lowest group of eGFR with the group with normal eGFR, prognostic significance was present in the entire period of follow-up with a hazard ratio between 1,97 (CI 1,65-2,35) and 1,35 (CI 0,99-1,84) in the 2-year periods.</p> <p>Conclusions</p> <p>One estimate of renal function is a strong and independent long-term prognostic factor for 10-12 years following a MI.</p