Home blood pressure monitoring improves the diagnosis of hypertension in hemodialysis patients

Using interdialytic ambulatory blood pressure (BP) recordings as the reference standard, we compared the performance of routine, standardized and home BP monitoring in 104 predominantly black patients on chronic hemodialysis for at least 3 months. Dialysis unit BP recordings were averaged over 2 weeks and home BP over 1 week. Awake ambulatory BP of ≥135 mmHg systolic or ≥85 mmHg diastolic was taken as evidence of hypertension. Average awake ambulatory BP was 128.1±21.6/73.5±13.5 mmHg, home BP 141.3±21.9/78.7±11.9 mmHg, standardized pre-dialysis BP 141.7±22.6/74.2±13.5 mmHg and post-dialysis 119.9±20.5/69.1±13.1 mmHg, routine pre-dialysis 145.4±21.8/79.0±13.1 mmHg and post-dialysis 131.5±19.2/72.5±11.4 mmHg. Sixty-three percent of the patients had well-controlled BP by ambulatory BP monitoring and isolated diastolic hypertension was rare (3%). The standard deviation of the differences between ambulatory and routine pre-dialysis BP was 17.6 mmHg, routine post-dialysis was 16.1 mmHg, standardized pre-dialysis was 16.4 mmHg, standardized post-dialysis was 14.1 mmHg, and home BP was 14.2 mmHg. The area under receiver operating characteristic curves was similar for home and standardized BP but lower for routine BP. Home systolic BP of ≥150 mmHg averaged over 1 week had the best combination of sensitivity (80%) and specificity (84.1%) in diagnosing systolic hypertension – present in 94% of the hypertensive dialysis patients. Home BP monitoring is similar to standardized recording of BP in hemodialysis patients. A systolic BP threshold of 150 mmHg at home averaged over 1 week serves as a useful predictor of hypertension diagnosed by ambulatory BP monitoring

Groundwater fluxes and flow paths within coastal barriers: Observations from a large-scale laboratory experiment (BARDEX II)

The dynamics of groundwater at the beach face land�ocean boundary have important implications to the exchange of water, nutrients, and pollutants between the ocean and coastal aquifers, and more subtly, varying groundwater levels may induce differing morphological response at the beach face. As a component of the multi-institution Barrier Dynamics Experiment (BARDEX II), groundwater fluxes and flow paths within a prototype-scale sandy barrier are quantified and reported at the three fundamental spatio-temporal scales (individual waves, the beach face, and total barrier), under controlled wave and water level conditions. A particular feature of the experimental programme was the inclusion of a back-barrier �lagoon�, that via a pump system and an intermediate water reservoir enabled the forcing of contrasting hydraulic gradients across the barrier. It was observed that the groundwater level, flow paths, and fluxes within the beach face region of the sand barrier were predominantly controlled by the action of waves at the beach face, regardless of the overall seaward- or landward-directed barrier-scale hydraulic gradients. In the presence of waves, all tests undertaken to complete this study developed a seaward gradient in this zone under the influence of waves. As a further result of wave forcing at the beach face boundary, localised groundwater flow divides were observed to develop, further partitioning the circulation and flow paths of groundwater within the prototype-scale sand barrier

Precise Tight-binding Description of the Band Structure of MgB2

We present a careful recasting of first-principles band structure calculations for MgB2 in a non-orthogonal sp-tight-binding (TB) basis. Our TB results almost exactly reproduce our full potential linearized augmented plane wave results for the energy bands, the densities of states and the total energies. Our procedure generates transferable Slater-Koster parameters which should be useful for other studies of this important material.Comment: REVTEX, 2 Encapsulated PostScript Figure

Phonon Dispersion Relations in PrBa2Cu3O6+x (x ~ 0.2)

We report measurements of the phonon dispersion relations in non-superconducting, oxygen-deficient PrBa2Cu3O6+x (x ~ 0.2) by inelastic neutron scattering. The data are compared with a model of the lattice dynamics based on a common interaction potential. Good agreement is achieved for all but two phonon branches, which are significantly softer than predicted. These modes are found to arise predominantly from motion of the oxygen ions in the CuO2 planes. Analogous modes in YBa2Cu3O6 are well described by the common interaction potential model.Comment: 4 pages, 3 figures. Minor changes following referees' comment

Geometric Generalisations of SHAKE and RATTLE

A geometric analysis of the Shake and Rattle methods for constrained Hamiltonian problems is carried out. The study reveals the underlying differential geometric foundation of the two methods, and the exact relation between them. In addition, the geometric insight naturally generalises Shake and Rattle to allow for a strictly larger class of constrained Hamiltonian systems than in the classical setting. In order for Shake and Rattle to be well defined, two basic assumptions are needed. First, a nondegeneracy assumption, which is a condition on the Hamiltonian, i.e., on the dynamics of the system. Second, a coisotropy assumption, which is a condition on the geometry of the constrained phase space. Non-trivial examples of systems fulfilling, and failing to fulfill, these assumptions are given

Onset of magnetism in B2 transition metals aluminides

Ab initio calculation results for the electronic structure of disordered bcc Fe(x)Al(1-x) (0.4<x<0.75), Co(x)Al(1-x) and Ni(x)Al(1-x) (x=0.4; 0.5; 0.6) alloys near the 1:1 stoichiometry, as well as of the ordered B2 (FeAl, CoAl, NiAl) phases with point defects are presented. The calculations were performed using the coherent potential approximation within the Korringa-Kohn-Rostoker method (KKR-CPA) for the disordered case and the tight-binding linear muffin-tin orbital (TB-LMTO) method for the intermetallic compounds. We studied in particular the onset of magnetism in Fe-Al and Co-Al systems as a function of the defect structure. We found the appearance of large local magnetic moments associated with the transition metal (TM) antisite defect in FeAl and CoAl compounds, in agreement with the experimental findings. Moreover, we found that any vacancies on both sublattices enhance the magnetic moments via reducing the charge transfer to a TM atom. Disordered Fe-Al alloys are ferromagnetically ordered for the whole range of composition studied, whereas Co-Al becomes magnetic only for Co concentration >0.5.Comment: 11 pages with 9 embedded postscript figures, to be published in Phys.Rev.

First- principle calculations of magnetic interactions in correlated systems

We present a novel approach to calculate the effective exchange interaction parameters based on the realistic electronic structure of correlated magnetic crystals in local approach with the frequency dependent self energy. The analog of ``local force theorem'' in the density functional theory is proven for highly correlated systems. The expressions for effective exchange parameters, Dzialoshinskii- Moriya interaction, and magnetic anisotropy are derived. The first-principle calculations of magnetic excitation spectrum for ferromagnetic iron, with the local correlation effects from the numerically exact QMC-scheme is presented.Comment: 17 pages, 3 Postscript figure

The calibration of the Sudbury Neutrino Observatory using uniformly distributed radioactive sources

The production and analysis of distributed sources of 24Na and 222Rn in the Sudbury Neutrino Observatory (SNO) are described. These unique sources provided accurate calibrations of the response to neutrons, produced through photodisintegration of the deuterons in the heavy water target, and to low energy betas and gammas. The application of these sources in determining the neutron detection efficiency and response of the 3He proportional counter array, and the characteristics of background Cherenkov light from trace amounts of natural radioactivity is described.Comment: 24 pages, 13 figure

X-ray standing wave and reflectometric characterization of multilayer structures

Microstructural characterization of synthetic periodic multilayers by x-ray standing waves have been presented. It has been shown that the analysis of multilayers by combined x-ray reflectometry (XRR) and x-ray standing wave (XSW) techniques can overcome the deficiencies of the individual techniques in microstructural analysis. While interface roughnesses are more accurately determined by the XRR technique, layer composition is more accurately determined by the XSW technique where an element is directly identified by its characteristic emission. These aspects have been explained with an example of a 20 period Pt/C multilayer. The composition of the C-layers due to Pt dissolution in the C-layers, Pt$_{x}$C$_{1-x}$, has been determined by the XSW technique. In the XSW analysis when the whole amount of Pt present in the C-layers is assumed to be within the broadened interface, it l eads to larger interface roughness values, inconsistent with those determined by the XRR technique. Constraining the interface roughness values to those determined by the XRR technique, requires an additional amount of dissolved Pt in the C-layers to expl ain the Pt fluorescence yield excited by the standing wave field. This analysis provides the average composition Pt$_{x}$C$_{1-x}$ of the C-layers .Comment: 12 pages RevTex, 10 eps figures embedde