The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Manfred J Muller - One of the best experts on this subject based on the ideXlab platform.
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Phase Angle from bioelectrical impedance analysis population reference values by age sex and body mass index
Journal of Parenteral and Enteral Nutrition, 2006Co-Authors: Anja Bosywestphal, Sandra Danielzik, Ralfpeter Dorhofer, Wiebke Later, Sonja Wiese, Manfred J MullerAbstract:Background: The use of bioelectrical impedance Phase Angle has been recommended as a prognostic tool in the clinical setting, but published reference data bases are discrepant and incomplete (eg, they do not consider body mass index [BMI], and data are lacking for children). Methods: Phase Angle reference values stratified by age, sex, and BMI were generated in a large German data base of 15,605 children and adolescents and 214,732 adults, and the determinants of Phase Angle values were assessed. The reference values were applied to 3 groups of patients and compared with previously published reference values from the United States and Switzerland. Results: Gender and age were the main determinants of Phase Angle in adults, with men and younger subjects having higher Phase Angles. In children and adolescents, age and BMI were the main determinants of Phase Angle. In normal and overweight adults, Phase Angle increased with increasing BMI, but there was an inverse association at a BMI >40 kg/m2. In cirrhosis...
Anja Bosywestphal - One of the best experts on this subject based on the ideXlab platform.
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cutoff percentiles of bioelectrical Phase Angle predict functionality quality of life and mortality in patients with cancer
The American Journal of Clinical Nutrition, 2010Co-Authors: Kristina Norman, Anja Bosywestphal, N Stobaus, Daniela Zocher, Antje Szramek, Ramona Scheufele, C Smoliner, Matthias PirlichAbstract:Background: The bioelectrical Phase Angle has shown predictive potential in various diseases, but general cutoffs are lacking in the clinical setting. Objectives: This study evaluated the prognostic value of the fifth percentile of sex-, age-, and body mass index‐stratified Phase Angle reference values in patients with cancer with respect to nutritional and functional status, quality of life, and 6-mo mortality. In a second step, we also studied the effect of the standardized Phase Angle (with a z score to determine individual deviations from the population average) on these variables. Design: A total of 399 patients with cancer were studied. Phase Angle was obtained with bioelectrical impedance analysis; muscle function was assessed by handgrip strength and peak expiratory flow. Quality of life was determined by the European Organization for Research and Treatment of Cancer questionnaire. Nutritional status was assessed by using Subjective Global Assessment. Survival of patients was documented after 6 mo. Results: Patients with a Phase Angle of less than the fifth reference percentile had significantly lower nutritional and functional status, impaired quality of life (P , 0.0001), and increased mortality (P , 0.001). The standardized Phase Angle emerged as a significant predictor for malnutrition and impaired functional status in generalized linear model regression analyses. It was also a stronger indicator of 6-mo survival than were malnutrition and disease severity in the Cox regression model (P , 0.0001) and according to the receiver operating characteristic curve. Conclusions: The standardized Phase Angle is an independent predictor for impaired nutritional and functional status and survival. The fifth Phase Angle reference percentile is a simple and prognostically relevant cutoff for detection of patients with cancer at risk for these factors. Am J Clin Nutr 2010;92:612‐9.
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Phase Angle from bioelectrical impedance analysis population reference values by age sex and body mass index
Journal of Parenteral and Enteral Nutrition, 2006Co-Authors: Anja Bosywestphal, Sandra Danielzik, Ralfpeter Dorhofer, Wiebke Later, Sonja Wiese, Manfred J MullerAbstract:Background: The use of bioelectrical impedance Phase Angle has been recommended as a prognostic tool in the clinical setting, but published reference data bases are discrepant and incomplete (eg, they do not consider body mass index [BMI], and data are lacking for children). Methods: Phase Angle reference values stratified by age, sex, and BMI were generated in a large German data base of 15,605 children and adolescents and 214,732 adults, and the determinants of Phase Angle values were assessed. The reference values were applied to 3 groups of patients and compared with previously published reference values from the United States and Switzerland. Results: Gender and age were the main determinants of Phase Angle in adults, with men and younger subjects having higher Phase Angles. In children and adolescents, age and BMI were the main determinants of Phase Angle. In normal and overweight adults, Phase Angle increased with increasing BMI, but there was an inverse association at a BMI >40 kg/m2. In cirrhosis...
Richard N Pierson - One of the best experts on this subject based on the ideXlab platform.
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bioelectrical impedance analysis population reference values for Phase Angle by age and sex
The American Journal of Clinical Nutrition, 2005Co-Authors: Maria Cristina G Barbosasilva, Aluisio J D Barros, Jack Wang, Steven B Heymsfield, Richard N PiersonAbstract:Background: Phase Angle is an indicator based on reactance and resistance obtained from bioelectrical impedance analysis (BIA). Although its biological meaning is still not clear, Phase Angle appears to have an important prognostic role. Objective: The aim of this study was to estimate population averages and SDs of Phase Angle that can be used as reference values. Design: BIA and other methods used to evaluate body composition, including hydrodensitometry and total body water, were completed in 1967 healthy adults aged 18-94 y. Phase Angle was calculated directly from body resistance and reactance, and fat mass (FM) was estimated from the combination of weight, hydrodensitometry, and total body water by using the 3-compartment Siri equation. Phase Angle values were compared across categories of sex, age, body mass index (BMI), and percentage FM. Results: Phase Angle was significantly (P < 0.001) smaller in women than in men and was lower with greater age (P < 0.001). Phase Angle increased with an increase in BMI and was significantly inversely associated with percentage fat in men. Phase Angle was significantly predicted from sex, age, BMI, and percentage FM in multiple regression models. Conclusions: Phase Angle differs across categories of sex, age, BMI, and percentage fat. These reference values can serve as a basis for Phase Angle evaluations in the clinical setting.
Christoph Schick - One of the best experts on this subject based on the ideXlab platform.
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Phase Angle correction for TMDSC in the glass-transition region
Thermochimica Acta, 1997Co-Authors: S. Weyer, A. Hensel, Christoph SchickAbstract:Abstract Temperature-modulated DSC (TMDSC) allows the determination of frequency (time) dependent heat capacities. If heat capacity is frequency dependent, for example, in the glass-transition region, one get a Phase Angle between heating rate and heat-flow rate which is related to material intrinsic properties. Because heat does not propagate but flows, the time-consuming heat transfer into the sample yields an additional Phase Angle. This Phase Angle has to be taken into account if one wants to calculate the imaginary part of the complex heat capacity of the sample from the measured Phase Angle. The heat transfer related Phase Angle depends on frequency, heat capacity and heat conductance. In the case of glass-transition, heat capacity and heat conductance may change in the respective temperature interval. A correction for the corresponding Phase Angle is suggested.
Yilu Liu - One of the best experts on this subject based on the ideXlab platform.
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Single-Phase Phase Angle Measurements in Electric Power Systems
IEEE Transactions on Power Systems, 2010Co-Authors: Tao Xia, Yilu LiuAbstract:Computation of Phase Angles using the discrete Fourier transform (DFT) algorithm has been proven to be sufficiently accurate in a variety of power system applications when the input signal is three-Phase voltage and the voltage frequency is near the nominal value. However, the performance of the DFT algorithm in time of the singe-Phase voltage input with a large frequency excursion so far has not been well explored, much less documented. This paper briefly discusses the importance of the synchronized Phase Angle measurement in power systems, and brings up the necessity of research on single-Phase measurement systems. The performance of the DFT algorithm in power system Phase Angle measurements is thoroughly analyzed. Corresponding rectifying methods, including quasi-positive-sequence DFT and offset compensation, are proposed and examined by relevant numerical simulations and necessary laboratory tests. The results of the simulations and tests show a perfect match between the derived equations and the Phase Angle data, and thus verify the effectiveness of the proposed algorithm, which is believed to be able to greatly improve the performance of DFT in the aspect of Phase Angle calculation when severe power system upsets with remarkable frequency excursions are present.
