Search results for "phase angle"
showing 10 items of 25 documents
Bioelectrical characteristics of type 1 and type 2 diabetic subjects with reference to body water compartments.
1998
Since bioelectrical characteristics correspond well to body water compartments, this study investigated bioelectrical differences between type 1 and type 2 diabetic subjects that could reflect differences in body water compartments. We investigated cross-sectionally 612 adult subjects, classified into 10 groups according to sex and disease (control, obese normal glucose tolerant, non-obese type 2 diabetes, obese type 2 diabetes, type 1 diabetes). Resistance (R), reactance (Xc) and phase angle (PA) were measured (800 microA - 50 kHz alternating current). The bioelectrical vector was obtained by plotting R and Xc normalized for height (ht), it is easily identified on the basis of the length (…
Effect of influenza-induced fever on human bioimpedance values.
2015
Background and Aims Bioelectrical impedance analysis (BIA) is a widely used technique to assess body composition and nutritional status. While bioelectrical values are affected by diverse variables, there has been little research on validation of BIA in acute illness, especially to understand prognostic significance. Here we report the use of BIA in acute febrile states induced by influenza. Methods Bioimpedance studies were conducted during an H1N1 influenza A outbreak in Venezuelan Amerindian villages from the Amazonas. Measurements were performed on 52 subjects between 1 and 40 years of age, and 7 children were re-examined after starting Oseltamivir treatment. Bioelectrical Impedance Vec…
Reliability and variability of bioimpedance measures in normal adults: Effects of age, gender, and body mass
2003
This study aimed to analyze the reliability and evaluate the causes of variability of bioimpedance parameters. Direct measures were analyzed because they are not affected by inappropriate prediction models. Resistance (R), reactance (Xc), and phase angle (PA) were determined at three fixed frequencies (5, 50, and 100 kHz) in 653 normal Germans (244 males and 409 females), aged 20-90 years, using a phase-sensitive whole-body tetrapolar bioimpedance analyzer (BIA 2000-M, Data Input, Germany). From these values, six bioimpedance ratios were calculated (R(5)/R(50), R(5)/R(100), Xc(5)/Xc(50), Xc(5)/Xc(100), PA(5)/PA(50), and PA(5)/PA(100)). Reliability of duplicate measurements, as determined by…
Thermal inertia mapping from NOAA-AVHRR data
1998
Abstract This paper presents a method to retrieve thermal inertia from NOAA-AVHRR data. The method, based on Xue and Cracknell's model (1992), involves using the phase angle information of the diurnal surface temperature change. The method needs three different NOAA overpasses of the same area throughout a single diurnal cycle. To apply this method we present a methodology that takes into account satellite calibrations, viewing geometry and correction of atmospheric effects. The advantage is that it does not need other data than the ones supplied by the satellite. Finally, we present the preliminary results obtained using the proposed method and the methodology for AVHRR data over the Iberi…
Study ofJ/ψ→pp¯andJ/ψ→nn¯
2012
The decays J/psi -> p (p) over bar and J/psi -> n (n) over bar have been investigated with a sample of 225.2 x 10(6) J/psi events collected with the BESIII detector at the BEPCII e(+)e(-) collider. The branching fractions are determined to be B(J/psi -> p (p) over bar) = (2.112 +/- 0.004 +/- 0.031 x 10(-3) and B(J/psi -> n (n) over bar) =(2.07 +/- 0.01 +/- 0.17) x 10(-3). Distributions of the angle theta between the proton or antineutron and the beam direction are well described by the form 1 + alpha cos(2)theta, and we find alpha = 0.595 +/- 0.012 +/- 0.015 for J/psi -> p (p) over bar and alpha = 0.50 +/- 0.04 +/- 0.21 for J/psi -> n (n) over bar. Our branching- fraction results suggest a …
Airborne measurement of hot spot reflectance signatures
2004
The so-called hot spot is a fine directional signature of the surface reflectance observed for phase angles close to zero. In this paper, we analyze and discuss several such signatures acquired from the airborne POLDER and HyMap instruments during the DAISEX'99 campaign over agricultural crops. The observed signatures are very similar to those acquired from space at a resolution of several tens of kilometers [J. Geophys. Res. 107 (2002)], which provides further evidence that the hot spot is a scale-free feature. The hot spots can be fitted by a two-parameter function (amplitude and width) of the phase angle derived from canopy radiative transfer modeling. The model predicts that the amplitu…
A Multiplicity result for a class of strongly indefinite asymptotically linear second order systems
2010
We prove a multiplicity result for a class of strongly indefinite nonlinear second order asymptotically linear systems with Dirichlet boundary conditions. The key idea for the proof is to bring together the classical shooting method and the Maslov index of the linear Hamiltonian systems associated to the asymptotic limits of the given nonlinearity.
Uncertainty evaluation in power measurements with commercial data acquisition boards
2011
The paper deals with the metrological characterization of a digital wattmeter developed by using a personal computer, a shunt, two commercial data acquisition boards and commercial software. The uncertainty of the active power measurements is assessed individually characterizing the voltage channel, the current channel and the phase displacement measurement between the two channels. In particular, the uncertainty on the voltage and current rms measurements is evaluated by using an already proposed approach based on the Monte Carlo method and on the usage of five parameters, while the uncertainty on the phase angle is experimentally estimated. In order to validate the proposed approach for t…
An extension of the fractional model for construction of asphalt binder master curve
2015
Knowledge and prediction of viscoelastic behaviour of asphalt binder is of great interest in order to design asphalt mixtures for civil construction of road and airports with good performances. The capability of a fractional model – requiring a very limited number of parameters – to describe and predict the linear viscoelastic behaviour of asphalt binder subjected to sinusoidal oscillations is investigated. Experimental data of complex modulus, |G*|, and phase angle, δ, are used to validate the proposed constitutive model. Based on the proposed extension of a fractional model, complex modulus isotherms for a range of frequencies can be created simply starting from isochronals at frequency v…
Rheological Behaviors of Waste Polyethylene Modified Asphalt Binder: Statistical Analysis of Interlaboratory Testing Results
2023
This article investigated the effect of waste polyethylene (PE) on the modified asphalt binders' rheological behavior from a statistical point of view. The interlaboratory testing results from the RILEM Technical Committee 279 Valorization of Waste and Secondary Materials for Roads Task Group 1 were used for this purpose. First, an unaged 70/100 penetration graded neat binder was selected as the reference material. Next, a single 5 % content of waste PE additives (PE-pellets and PE-shreds) was mixed with a 95 % neat binder to prepare two PE modified binders. Then, dynamic shear rheometer-based temperature-frequency sweep tests were performed over a wide range of temperatures and frequencies…