2,289 research outputs found

    Estimation of renal function by CKD-EPI versus MDRD in a cohort of HIV-infected patients: a cross-sectional analysis

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    Background: Accurately determining renal function is essential for clinical management of HIV patients. Classically, it has been evaluated by estimating glomerular filtration rate (eGFR) with the MDRD-equation, but today there is evidence that the new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation has greater diagnostic accuracy. To date, however, little information exists on patients with HIV-infection. This study aimed to evaluate eGFR by CKD-EPI vs. MDRD equations and to stratify renal function according to KDIGO guidelines. Methods: Cross-sectional, single center study including adult patients with HIV-infection. Results: Four thousand five hundred three patients with HIV-infection (864 women19%) were examined. Median age was 45 years (IQR 37-52), and median baseline creatinine was 0.93 mg/dL (IQR 0.82-1.05). A similar distribution of absolute measures of eGFR was found using both formulas (p = 0.548). Baseline median eGFR was 95.2 and 90.4 mL/min/ 1.73 m(2) for CKD-EPI and MDRD equations (p 90 mL/min/1.73 m(2)) in 73% patients and '' mild reduced GFR '' (60-89 mL/min/1.73 m(2)) in 24.3% of the patients, formerly classified as >60 mL/min/1.73 m(2) with MDRD. Conclusions: There was good correlation between CKD-EPI and MDRD. Estimating renal function using CKD-EPI equation allowed better staging of renal function and should be considered the method of choice. CKD-EPI identified a significant proportion of patients (24%) with mild reduced GFR (60-89 mL/min/1.73 m(2)).Red de SidaInstituto de Salud Carlos III, Madrid, SpainEuropean Regional Development Fund (ERDF)Univ Fed Sao Paulo, Kidney Transplant Div, Hosp Rim, Sao Paulo, BrazilUniv Barcelona, Hosp Clin IDIBAPS, Nephrol & Renal Transplantat Serv, Barcelona, SpainHosp Clin Barcelona, Biomed Diag Ctr, Core Lab, Barcelona, SpainHosp Olot, Internal Med Serv, Girona, SpainUniv Girona, Dept Med Sci, Girona, SpainUniv Barcelona, Hosp Clin IDIBAPS, Infect Dis Serv, Barcelona, SpainUniv Fed Sao Paulo, Kidney Transplant Div, Hosp Rim, Sao Paulo, BrazilRed de Sida: RD12/0017/0001Instituto de Salud Carlos III, Madrid, Spain: INT15/00168Web of Scienc

    VLA H53alpha radio recombination line observations of the ultraluminous infrared galaxy Arp 220

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    We present high angular resolution (0.7'') observations made with the Very Large Array (VLA) of the radio recombination line (RRL) H53alpha and radio continuum emission at 43 GHz from the ultraluminous infrared galaxy (ULIRG) Arp 220. The 43 GHz continuum emission shows a compact structure (~2'') with two peaks separated by ~1'', the East (E) and West (W) components, that correspond to each galactic nucleus of the merger. The spectral indices for both the E and W components, using radio continuum images at 8.3 and 43 GHz are typical of synchrotron emission (alpha ~ -1.0). Our 43 GHz continuum and H53alpha line observations confirm the flux densities predicted by the models proposed by Anantharamaiah et al. This agreement with the models implies the presence of high-density (~ 100,000 cm^-3) compact HII regions (~ 0.1 pc) in Arp 220. The integrated H53alpha line emission is stronger toward the non-thermal radio continuum peaks, which are also coincident with the peaks of molecular emission of the H2CO. The coincidence between the integrated H53alpha and the H2CO maser line emission suggests that the recent star forming regions, traced by the high density gas, are located mainly in regions that are close to the two radio continuum peaks. A velocity gradient of ~ 0.30 km/s/pc in the H53alpha RRL is observed toward the E component and a second velocity gradient of ~ 0.15 km/s/pc is detected toward the W component. The orientations of these velocity gradients are in agreement with previous CO, HI and OH observations. The kinematics of the high-density ionized gas traced by the H53alpha line are consistent with two counter rotating disks as suggested by the CO and HI observations.Comment: The original version was published in the ApJ,633,198,2005. This new version is submitted with the corrected velocity scal

    Raphtory: The temporal graph engine for Rust and Python

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    Raphtory is a platform for building and analysing temporal networks. The library includes methods for creating networks from a variety of data sources; algorithms to explore their structure and evolution; and an extensible GraphQL server for deployment of applications built on top. Raphtory’s core engine is built in Rust, for efficiency, with Python interfaces, for ease of use. Raphtory is developed by network scientists, with a background in Physics, Applied Mathematics, Engineering and Computer Science, for use across academia and industry

    Mean Field Approximations and Multipartite Thermal Correlations

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    The relationship between the mean-field approximations in various interacting models of statistical physics and measures of classical and quantum correlations is explored. We present a method that allows us to bound the total amount of correlations (and hence entanglement) in a physical system in thermal equilibrium at some temperature in terms of its free energy and internal energy. This method is first illustrated using two qubits interacting through the Heisenberg coupling, where entanglement and correlations can be computed exactly. It is then applied to the one dimensional Ising model in a transverse magnetic field, for which entanglement and correlations cannot be obtained by exact methods. We analyze the behavior of correlations in various regimes and identify critical regions, comparing them with already known results. Finally, we present a general discussion of the effects of entanglement on the macroscopic, thermodynamical features of solid-state systems. In particular, we exploit the fact that a dd dimensional quantum system in thermal equilibrium can be made to corresponds to a d+1 classical system in equilibrium to substitute all entanglement for classical correlations.Comment: 17 pages, 6 figure

    Renyi Entropy of the XY Spin Chain

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    We consider the one-dimensional XY quantum spin chain in a transverse magnetic field. We are interested in the Renyi entropy of a block of L neighboring spins at zero temperature on an infinite lattice. The Renyi entropy is essentially the trace of some power α\alpha of the density matrix of the block. We calculate the asymptotic for LL \to \infty analytically in terms of Klein's elliptic λ\lambda - function. We study the limiting entropy as a function of its parameter α\alpha. We show that up to the trivial addition terms and multiplicative factors, and after a proper re-scaling, the Renyi entropy is an automorphic function with respect to a certain subgroup of the modular group; moreover, the subgroup depends on whether the magnetic field is above or below its critical value. Using this fact, we derive the transformation properties of the Renyi entropy under the map αα1\alpha \to \alpha^{-1} and show that the entropy becomes an elementary function of the magnetic field and the anisotropy when α\alpha is a integer power of 2, this includes the purity trρ2tr \rho^2. We also analyze the behavior of the entropy as α0\alpha \to 0 and \infty and at the critical magnetic field and in the isotropic limit [XX model].Comment: 28 Pages, 1 Figur

    Quantum Entanglement in Second-quantized Condensed Matter Systems

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    The entanglement between occupation-numbers of different single particle basis states depends on coupling between different single particle basis states in the second-quantized Hamiltonian. Thus in principle, interaction is not necessary for occupation-number entanglement to appear. However, in order to characterize quantum correlation caused by interaction, we use the eigenstates of the single-particle Hamiltonian as the single particle basis upon which the occupation-number entanglement is defined. Using the proper single particle basis, we discuss occupation-number entanglement in important eigenstates, especially ground states, of systems of many identical particles. The discussions on Fermi systems start with Fermi gas, Hatree-Fock approximation, and the electron-hole entanglement in excitations. The entanglement in a quantum Hall state is quantified as -fln f-(1-f)ln(1-f), where f is the proper fractional part of the filling factor. For BCS superconductivity, the entanglement is a function of the relative momentum wavefunction of the Cooper pair, and is thus directly related to the superconducting energy gap. For a spinless Bose system, entanglement does not appear in the Hatree-Gross-Pitaevskii approximation, but becomes important in the Bogoliubov theory.Comment: 11 pages. Journal versio

    Cherenkov Telescope Array Data Management

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    Very High Energy gamma-ray astronomy with the Cherenkov Telescope Array (CTA) is evolving towards the model of a public observatory. Handling, processing and archiving the large amount of data generated by the CTA instruments and delivering scientific products are some of the challenges in designing the CTA Data Management. The participation of scientists from within CTA Consortium and from the greater worldwide scientific community necessitates a sophisticated scientific analysis system capable of providing unified and efficient user access to data, software and computing resources. Data Management is designed to respond to three main issues: (i) the treatment and flow of data from remote telescopes; (ii) "big-data" archiving and processing; (iii) and open data access. In this communication the overall technical design of the CTA Data Management, current major developments and prototypes are presented.Comment: 8 pages, 2 figures, In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589
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