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Sample records for impedance analysis bia

  1. [Abdomen specific bioelectrical impedance analysis (BIA) methods for evaluation of abdominal fat distribution].

    Science.gov (United States)

    Ida, Midori; Hirata, Masakazu; Hosoda, Kiminori; Nakao, Kazuwa

    2013-02-01

    Two novel bioelectrical impedance analysis (BIA) methods have been developed recently for evaluation of intra-abdominal fat accumulation. Both methods use electrodes that are placed on abdominal wall and allow evaluation of intra-abdominal fat area (IAFA) easily without radiation exposure. Of these, "abdominal BIA" method measures impedance distribution along abdominal anterior-posterior axis, and IAFA by BIA method(BIA-IAFA) is calculated from waist circumference and the voltage occurring at the flank. Dual BIA method measures impedance of trunk and body surface at the abdominal level and calculates BIA-IAFA from transverse and antero-posterior diameters of the abdomen and the impedance of trunk and abdominal surface. BIA-IAFA by these two BIA methods correlated well with IAFA measured by abdominal CT (CT-IAFA) with correlatipn coefficient of 0.88 (n = 91, p abdominal adiposity in clinical study and routine clinical practice of metabolic syndrome and obesity.

  2. Use of electrocardiogram (ECG) electrodes for Bioelectrical Impedance Analysis (BIA)

    International Nuclear Information System (INIS)

    Caicedo-Eraso, J C; González-Correa, C H; González-Correa, C A

    2012-01-01

    BIA is a safe, noninvasive, portable and relatively inexpensive method of estimating body composition that is practical and suitable for individual use and large-scale studies. However, the cost of the electrodes recommended by some BIA manufacturers is too high for developing countries; where very often the long and complicated process of importation reduces the time they can be used. The purpose of this study was to evaluate the use of two types of ECG electrodes (2290 and 2228 by 3M ® ) in BIA measurements to decrease the costs of the test. The results showed that the 2228 ECG electrodes can be used in BIA measurements for adult's body composition assessment. These electrodes are available in the domestic market and their costs are 92% lower than the electrodes recommended by manufacturer. The results show a new cost-benefit relation for BIA method and make this a more accessible tool for individual tests, large-scale researches and studies in the community.

  3. Preliminary bioelectrical impedance analysis (BIA) equation for body composition assessment in young females from Colombia

    International Nuclear Information System (INIS)

    Caicedo, J C; González-Correa, C H; González-Correa, C A

    2013-01-01

    A previous study showed that reported BIA equations for body composition are not suitable for Colombian population. The purpose of this study was to develop and validate a preliminary BIA equation for body composition assessment in young females from Colombia, using hydrodensitometry as reference method. A sample of 30 young females was evaluated. Inclusion and exclusion criteria were defined to minimize the variability of BIA. Height, weight, BIA, residual lung volume (RV) and underwater weight (UWW) were measured. A preliminary BIA equation was developed (r 2 = 0.72, SEE = 2.48 kg) by stepwise multiple regression with fat-free mass (FFM) as dependent variable and weight, height and impedance measurements as independent variables. The quality of regression was evaluated and a cross-validation against 50% of sample confirmed that results obtained with the preliminary BIA equation is interchangeable with results obtained with hydrodensitometry (r 2 = 0.84, SEE = 2.62 kg). The preliminary BIA equation can be used for body composition assessment in young females from Colombia until a definitive equation is developed. The next step will be increasing the sample, including a second reference method, as deuterium oxide dilution (D 2 O), and using multi-frequency BIA (MF-BIA). It would also be desirable to develop equations for males and other ethnic groups in Colombia.

  4. Bioelectrical impedance analysis (BIA) equations validation against hydrodensitometry in a Colombian population

    International Nuclear Information System (INIS)

    Caicedo-Eraso, J C; Gonzalez-Correa, C A; Gonzalez-Correa, C H

    2013-01-01

    Several studies have shown that the accuracy of BIA results depends of ethnicity, age, gender, hormonal and genetic variations and, so far, there are not specific equations for Colombian population. The purpose was to evaluate reported BIA equations to determine their usefulness in body composition assessment in young females from Colombia using hydrodensitometry as the reference method. A sample of 30 young females was evaluated. Inclusion and exclusion criteria were defined to minimize the variability of BIA. Height, weight, multi-frequency BIA, residual lung volume (RV) and underwater weight (UWW) were measured. Five BIA equations met the inclusion criteria of this study. Three equations overestimated and two equations underestimated body fat (BF). Paired Student t-test and Bland and Altman analysis (p<0.05) showed significant differences in four BIA equations. However, all standard error of estimate (SEE) to BF was greater than 2.7 kg. This study showed that the five selected BIA equations are not valid for estimation of body composition in young females from Colombia. It is recommended to develop BIA equations to improve BF fat assessment in our population.

  5. Bioelectrical impedance analysis (BIA) for sarcopenic obesity (SO) diagnosis in young female subjects

    International Nuclear Information System (INIS)

    González-Correa, C H; Caicedo-Eraso, J C; Villada-Gomez J S

    2013-01-01

    Sarcopenia is defined as a loss of muscle mass depending of ageing and affecting physical function (definition A). A new definition considers excluding mass reduction criterion (definition B). Obesity is pandemic and occurs at all ages. Sarcopenic obesity (SO) implies both processes. The purpose of this study was to compare the results obtained after applying these 2 definitions in 66 aged 22 ± 2.8 years overweight or obese young college women. Percentage body fat (%BF) and skeletal mass index (SMI) were estimated by BIA, muscle function by handgrip strength test (HGS) and physical performance by Harvard step test (HST). There were 9.1% and 90.9% overweight or obese subjects. Twenty nine subjects (43.9%) had decreased HGS and 22 (33.3%) had impaired physical performance. One obese subject (1.5%) met the criteria for sarcopenic obesity by definition A and 9 (13.6%) by definition B. Although a linear regression (α 2 = 0.094, 0.037 and 0.275 respectively) it was observed a tendency for HGS, HST and SMI deterioration when %BF increases. However, other confounding factors must be investigated. Probably as the population gets more obese, the problematic of SO will be found earlier in life.

  6. Multi-frequency bioelectrical impedance analysis (BIA) compared to magnetic resonance imaging (MRI) for estimation of fat-free mass in colorectal cancer patients treated with chemotherapy

    DEFF Research Database (Denmark)

    Palle, Stine Skov; Tang Møllehave, Line; Kadkhoda, Zahra Taheri

    2016-01-01

    during the course of their treatments. Objective: To examine relationships between single cross-sectional thighs magnetic resonance imaging (MRI), skeletal muscle mass (SM) as reference and multi-frequency bioelectrical impedance analysis (BIA) fat free mass (FFM) in patients with colorectal cancer...... undergoing chemotherapy. Design: In an observational, prospective study we examine the relationships between single cross-sectional thighs MRI (T1-weighted (1.5 T) SM compared to FFM BIA (8-electrodes multi-frequency Tanita MC780MA)) and FFM skin-fold thickness (ST) (4-points (Harpenden, Skinfold Caliper......)) and SM equation for non-obese persons from Lee et al. 2000 (L2000) (based on age, height, weight, sex and race). FFM and SM (kg) were calculated based on either area (MRI) or weight. Results: 18 CRC patients (10 males and 8 females) with mean (SD) age 67 yr (6) were measured at baseline, and 13 were...

  7. Smart Multi-Frequency Bioelectrical Impedance Spectrometer for BIA and BIVA Applications.

    Science.gov (United States)

    Harder, Rene; Diedrich, Andre; Whitfield, Jonathan S; Buchowski, Macie S; Pietsch, John B; Baudenbacher, Franz J

    2016-08-01

    Bioelectrical impedance analysis (BIA) is a noninvasive and commonly used method for the assessment of body composition including body water. We designed a small, portable and wireless multi-frequency impedance spectrometer based on the 12 bit impedance network analyzer AD5933 and a precision wide-band constant current source for tetrapolar whole body impedance measurements. The impedance spectrometer communicates via Bluetooth with mobile devices (smart phone or tablet computer) that provide user interface for patient management and data visualization. The export of patient measurement results into a clinical research database facilitates the aggregation of bioelectrical impedance analysis and biolectrical impedance vector analysis (BIVA) data across multiple subjects and/or studies. The performance of the spectrometer was evaluated using a passive tissue equivalent circuit model as well as a comparison of body composition changes assessed with bioelectrical impedance and dual-energy X-ray absorptiometry (DXA) in healthy volunteers. Our results show an absolute error of 1% for resistance and 5% for reactance measurements in the frequency range of 3 kHz to 150 kHz. A linear regression of BIA and DXA fat mass estimations showed a strong correlation (r(2)=0.985) between measures with a maximum absolute error of 6.5%. The simplicity of BIA measurements, a cost effective design and the simple visual representation of impedance data enables patients to compare and determine body composition during the time course of a specific treatment plan in a clinical or home environment.

  8. Bioelectrical impedance analysis--part I

    DEFF Research Database (Denmark)

    Kyle, Ursula G; Bosaeus, Ingvar; De Lorenzo, Antonio D

    2004-01-01

    The use of bioelectrical impedance analysis (BIA) is widespread both in healthy subjects and patients, but suffers from a lack of standardized method and quality control procedures. BIA allows the determination of the fat-free mass (FFM) and total body water (TBW) in subjects without significant...

  9. Muscle development in healthy children evaluated by bioelectrical impedance analysis.

    Science.gov (United States)

    Uchiyama, Tomoka; Nakayama, Takahiro; Kuru, Satoshi

    2017-02-01

    This study aimed to use bioelectrical impedance analysis (BIA) to generate a new muscle density index (MDI), the MDI_BIA, to evaluate muscle development, and to demonstrate the changes that occur in the BIA-based muscle cross-sectional area index (MCAI_BIA) that accompany growth. We also sought to determine the traceability of chronological changes in the MDI_BIA and MCAI_BIA. Healthy children (n=112) aged 8.68±3.16years (0.33-14.00years) underwent bioelectrical impedance (BI) measurements of their upper arms, thighs, and lower legs. The MDI_BIA and MCAI_BIA were calculated, and cross-sectional investigations were conducted into the changes in these indices that accompanied growth. Data collected after 1.10±0.08years from 45 participants determined the traceability of the chronological changes in the MDI_BIA and MCAI_BIA. The MDI_BIA and MCAI_BIA were significantly positively correlated with age and height at all locations (Pchildren, and they showed significant chronological increases. Hence, these indices could be used to represent muscle development and muscle mass increases. BIA is non-invasive, convenient, and economical and it may be useful in evaluating muscle development and muscle cross-sectional areas in children. Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  10. Bioelectrical impedance analysis to estimate body composition in surgical and oncological patients: a systematic review

    NARCIS (Netherlands)

    Haverkort, E. B.; Reijven, P. L. M.; Binnekade, J. M.; de van der Schueren, M. A. E.; Earthman, C. P.; Gouma, D. J.; de Haan, R. J.

    2015-01-01

    Bioelectrical impedance analysis (BIA) is a commonly used method for the evaluation of body composition. However, BIA estimations are subject to uncertainties.The aim of this systematic review was to explore the variability of empirical prediction equations used in BIA estimations and to evaluate

  11. Feasibility of bioelectrical impedance analysis in persons with severe intellectual and visual disabilities

    NARCIS (Netherlands)

    Havinga-Top, Thamar; Waninge, Aly; van der Schans, Cees; Jager, Harriët

    2015-01-01

    Background: Body composition measurements provide importanti nformation about physical fitness and nutritional status. People with severe intellectual and visual disabilities (SIVD) have an increased risk for altered body composition. Bioelectrical impedance analysis (BIA) has been evidenced as a

  12. Feasibility of bioelectrical impedance analysis in persons with severe intellectual and visual disabilities

    NARCIS (Netherlands)

    Havinga-Top, A. M.; Waninge, A.; van der Schans, C. P.; Jager-Wittenaar, H.

    2015-01-01

    Background: Body composition measurements provide important information about physical fitness and nutritional status. People with severe intellectual and visual disabilities (SIVD) have an increased risk for altered body composition. Bioelectrical impedance analysis (BIA) has been evidenced as a

  13. BIOELECTRICAL IMPEDANCE VECTOR ANALYSIS IDENTIFIES SARCOPENIA IN NURSING HOME RESIDENTS

    Science.gov (United States)

    Loss of muscle mass and water shifts between body compartments are contributing factors to frailty in the elderly. The body composition changes are especially pronounced in institutionalized elderly. We investigated the ability of single-frequency bioelectrical impedance analysis (BIA) to identify b...

  14. Validation of bioelectrical-impedance analysis as a measurement of change in body composition in obesity

    International Nuclear Information System (INIS)

    Kushner, R.F.; Kunigk, A.; Alspaugh, M.; Andronis, P.T.; Leitch, C.A.; Schoeller, D.A.

    1990-01-01

    The bioelectrical-impedance-analysis (BIA) method accurately measures body composition in weight-stable subjects. This study validates the use of BIA to measure change in body composition. Twelve obese females underwent weight loss at a mean rate of 1.16 kg/wk. Body composition was measured by deuterium oxide dilution (D2O), BIA, and skinfold anthropometry (SFA) at baseline and at 5% decrements in weight. Highly significant correlations were obtained between D2O and BIA (r = 0.971) and between D2O and SFA (r = 0.932). Overall, BIA predicted change in fat-free mass with greater accuracy (to 0.4 kg) and precision (+/- 1.28 kg) than did anthropometry (to 0.8 kg and +/- 2.58 kg, respectively). We conclude that BIA is a useful clinical method for measuring change in body composition

  15. Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets

    Directory of Open Access Journals (Sweden)

    Raquel D. Langer

    2016-03-01

    Full Text Available Background: Bioelectrical Impedance Analysis (BIA is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. Methods: A total of 396 males, Brazilian Army cadets, aged 17–24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM estimation, and dual-energy X-ray absorptiometry (DXA as a reference method. Student’s t-test (for paired sample, linear regression analysis, and Bland–Altman method were used to test the validity of the BIA equations. Results: Predictive BIA equations showed significant differences in FFM compared to DXA (p < 0.05 and large limits of agreement by Bland–Altman. Predictive BIA equations explained 68% to 88% of FFM variance. Specific BIA equations showed no significant differences in FFM, compared to DXA values. Conclusion: Published BIA predictive equations showed poor accuracy in this sample. The specific BIA equations, developed in this study, demonstrated validity for this sample, although should be used with caution in samples with a large range of FFM.

  16. Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets.

    Science.gov (United States)

    Langer, Raquel D; Borges, Juliano H; Pascoa, Mauro A; Cirolini, Vagner X; Guerra-Júnior, Gil; Gonçalves, Ezequiel M

    2016-03-11

    Bioelectrical Impedance Analysis (BIA) is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM) estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. A total of 396 males, Brazilian Army cadets, aged 17-24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM estimation, and dual-energy X-ray absorptiometry (DXA) as a reference method. Student's t-test (for paired sample), linear regression analysis, and Bland-Altman method were used to test the validity of the BIA equations. Predictive BIA equations showed significant differences in FFM compared to DXA (p FFM variance. Specific BIA equations showed no significant differences in FFM, compared to DXA values. Published BIA predictive equations showed poor accuracy in this sample. The specific BIA equations, developed in this study, demonstrated validity for this sample, although should be used with caution in samples with a large range of FFM.

  17. Does bioelectrical impedance analysis accurately estimate the condition of threatened and endangered desert fish species?

    Science.gov (United States)

    Dibble, Kimberly L.; Yard, Micheal D.; Ward, David L.; Yackulic, Charles B.

    2017-01-01

    Bioelectrical impedance analysis (BIA) is a nonlethal tool with which to estimate the physiological condition of animals that has potential value in research on endangered species. However, the effectiveness of BIA varies by species, the methodology continues to be refined, and incidental mortality rates are unknown. Under laboratory conditions we tested the value of using BIA in addition to morphological measurements such as total length and wet mass to estimate proximate composition (lipid, protein, ash, water, dry mass, energy density) in the endangered Humpback Chub Gila cypha and Bonytail G. elegans and the species of concern Roundtail Chub G. robusta and conducted separate trials to estimate the mortality rates of these sensitive species. Although Humpback and Roundtail Chub exhibited no or low mortality in response to taking BIA measurements versus handling for length and wet-mass measurements, Bonytails exhibited 14% and 47% mortality in the BIA and handling experiments, respectively, indicating that survival following stress is species specific. Derived BIA measurements were included in the best models for most proximate components; however, the added value of BIA as a predictor was marginal except in the absence of accurate wet-mass data. Bioelectrical impedance analysis improved the R2 of the best percentage-based models by no more than 4% relative to models based on morphology. Simulated field conditions indicated that BIA models became increasingly better than morphometric models at estimating proximate composition as the observation error around wet-mass measurements increased. However, since the overall proportion of variance explained by percentage-based models was low and BIA was mostly a redundant predictor, we caution against the use of BIA in field applications for these sensitive fish species.

  18. The use of bioelectrical impedance analysis for body composition in epidemiological studies

    DEFF Research Database (Denmark)

    Böhm, A; Heitmann, B L

    2013-01-01

    BACKGROUND/OBJECTIVES: Bioelectrical impedance analysis (BIA) is a relatively simple, inexpensive and non-invasive technique to measure body composition and is therefore suitable in field studies and larger surveys. SUBJECTS/METHODS: We performed an overview of BIA-derived body fat percentages (BF......%) from 55 published studies of healthy populations aged 6-80 years. In addition, the relationship between body mass index (BMI) and body composition is documented in the context of BIA as a good alternative to closely differentiate which composition of the body better relates to the risk...

  19. Bioelectrical impedance analysis for bovine milk: Preliminary results

    Science.gov (United States)

    Bertemes-Filho, P.; Valicheski, R.; Pereira, R. M.; Paterno, A. S.

    2010-04-01

    This work reports the investigation and analysis of bovine milk quality by using biological impedance measurements using electrical impedance spectroscopy (EIS). The samples were distinguished by a first chemical analysis using Fourier transform midinfrared spectroscopy (FTIR) and flow citometry. A set of milk samples (100ml each) obtained from 17 different cows in lactation with and without mastitis were analyzed with the proposed technique using EIS. The samples were adulterated by adding distilled water and hydrogen peroxide in a controlled manner. FTIR spectroscopy and flow cytometry were performed, and impedance measurements were made in a frequency range from 500Hz up to 1MHz with an implemented EIS system. The system's phase shift was compensated by measuring saline solutions. It was possible to show that the results obtained with the Bioelectrical Impedance Analysis (BIA) technique may detect changes in the milk caused by mastitis and the presence of water and hydrogen peroxide in the bovine milk.

  20. Fat-free mass prediction equations for bioelectric impedance analysis compared to dual energy X-ray absorptiometry in obese adolescents: a validation study

    NARCIS (Netherlands)

    Hofsteenge, G.H.; Chin A Paw, M.J.M.; Weijs, P.J.M.

    2015-01-01

    Background: In clinical practice, patient friendly methods to assess body composition in obese adolescents are needed. Therefore, the bioelectrical impedance analysis (BIA) related fat-free mass (FFM) prediction equations (FFM-BIA) were evaluated in obese adolescents (age 11-18 years) compared to

  1. The Effect of an Acute After-School Exercise Bout on Percentage of Body Fat Using Leg-to-Leg Bioelectrical Impedance Analysis in Children

    Science.gov (United States)

    Andreacci, Joseph L.; Dixon, Curt B.; Rompolski, Krista; VanGorden, Kelly M.

    2008-01-01

    Bioelectrical impedance analysis (BIA) is a fast, easy to administer, and relatively inexpensive method of evaluating body composition. Due to the ease of operation, interest in using BIA to estimate percentage of body fat (%BF) has grown, especially in settings where body composition assessments are often performed without the benefit of…

  2. Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management

    Directory of Open Access Journals (Sweden)

    Ahyoung Choi

    2015-09-01

    Full Text Available Current bioelectric impedance analysis (BIA systems are often large, cumbersome devices which require strict electrode placement on the user, thus inhibiting mobile capabilities. In this work, we developed a handheld BIA device that measures impedance from multiple frequencies (5 kHz~200 kHz with four contact electrodes and evaluated the BIA device against standard body composition analysis systems: a dual-energy X-ray absorptiometry (DXA system (GE Lunar Prodigy, GE Healthcare, Buckinghamshire, UK and a whole-body BIA system (InBody S10, InBody, Co. Ltd, Seoul, Korea. In the study, 568 healthy participants, varying widely in body mass index, age, and gender, were recruited at two research centers: the Samsung Medical Center (SMC in South Korea and the Pennington Biomedical Research Center (PBRC in the United States. From the measured impedance data, we analyzed individual body fat and skeletal muscle mass by applying linear regression analysis against target reference data. Results indicated strong correlations of impedance measurements between the prototype pathways and corresponding InBody S10 electrical pathways (R = 0.93, p < 0.0001. Additionally, body fat estimates from DXA did not yield significant differences (p > 0.728 (paired t-test, DXA mean body fat 29.45 ± 10.77 kg, estimated body fat 29.52 ± 12.53 kg. Thus, this portable BIA system shows a promising ability to estimate an individual’s body composition that is comparable to large stationary BIA systems.

  3. Estimation of total body water by bioelectrical impedance analysis

    International Nuclear Information System (INIS)

    Kushner, R.F.; Schoeller, D.A.

    1986-01-01

    Total body water (TBW) measured by bioelectrical impedance analysis (BIA) was directly compared with deuterium-isotope dilution in a total of 58 subjects. First, sex-specific and group equations were developed by multiple regression analysis in (10 each) obese and nonobese men and women. Height/resistive impedance was the most significant variable used to predict deuterium-dilution space (D2O-TBW) and, combined with weight, yielded R = 0.99 and SE of estimate = 1.75 L. Equations predicted D2O-TBW equally well for obese and nonobese subjects. Second, the equations were prospectively tested in a heterogeneous group of 6 males and 12 females. Sex-specific equations predicted D2O-TBW with good correlation coefficients (0.96 and 0.93), total error (2.34 and 2.89 L), and a small difference between mean predicted and measured D2O-TBW (-1.4 +/- 2.05 and -0.48 +/- 2.83 L). BIA predicts D2O-TBW more accurately than weight, height, and/or age. A larger population is required to validate the applicability of our equations

  4. Validity of bioelectrical impedance analysis in estimation of fat-free mass in colorectal cancer patients.

    Science.gov (United States)

    Ræder, Hanna; Kværner, Ane Sørlie; Henriksen, Christine; Florholmen, Geir; Henriksen, Hege Berg; Bøhn, Siv Kjølsrud; Paur, Ingvild; Smeland, Sigbjørn; Blomhoff, Rune

    2018-02-01

    Bioelectrical impedance analysis (BIA) is an accessible and cheap method to measure fat-free mass (FFM). However, BIA estimates are subject to uncertainty in patient populations with altered body composition and hydration. The aim of the current study was to validate a whole-body and a segmental BIA device against dual-energy X-ray absorptiometry (DXA) in colorectal cancer (CRC) patients, and to investigate the ability of different empiric equations for BIA to predict DXA FFM (FFM DXA ). Forty-three non-metastatic CRC patients (aged 50-80 years) were enrolled in this study. Whole-body and segmental BIA FFM estimates (FFM whole-bodyBIA , FFM segmentalBIA ) were calculated using 14 empiric equations, including the equations from the manufacturers, before comparison to FFM DXA estimates. Strong linear relationships were observed between FFM BIA and FFM DXA estimates for all equations (R 2  = 0.94-0.98 for both devices). However, there were large discrepancies in FFM estimates depending on the equations used with mean differences in the ranges -6.5-6.8 kg and -11.0-3.4 kg for whole-body and segmental BIA, respectively. For whole-body BIA, 77% of BIA derived FFM estimates were significantly different from FFM DXA , whereas for segmental BIA, 85% were significantly different. For whole-body BIA, the Schols* equation gave the highest agreement with FFM DXA with mean difference ±SD of -0.16 ± 1.94 kg (p = 0.582). The manufacturer's equation gave a small overestimation of FFM with 1.46 ± 2.16 kg (p FFM DXA (0.17 ± 1.83 kg (p = 0.546)). Using the manufacturer's equation, no difference in FFM estimates was observed (-0.34 ± 2.06 kg (p = 0.292)), however, a clear proportional bias was detected (r = 0.69, p FFM compared to DXA using the optimal equation. In a population of non-metastatic CRC patients, mostly consisting of Caucasian adults and with a wide range of body composition measures, both the whole-body BIA and segmental BIA device

  5. V-dotO2max prediction from multi-frequency bioelectrical impedance analysis

    International Nuclear Information System (INIS)

    Stahn, Alexander; Strobel, Günther; Terblanche, Elmarie

    2008-01-01

    Bioelectrical impedance analysis (BIA) has been shown to be highly related to skeletal muscle mass and blood volume, both of which are important determinants of maximal oxygen uptake (V-dotO 2max ). The aim of the present study was therefore to investigate the ability of whole-body and segmental multi-frequency BIA to improve current nonexercise V-dotO 2max prediction models. Data for V-dotO 2max (mL min −1 ), anthropometry, self-reported physical activity (PA-R) and BIA were collected in 115 men and women. Multiple linear regression analysis (MLR) was used to develop the most parsimonious prediction model. Segmental BIA was not superior to whole-body measurements. Correlation coefficients between V-dotO 2max and resistance indices were significantly higher at 500 kHz compared to 50 kHz (p 2max (r = 0.89). After adjusting for age, gender and PA-R, MLR revealed that the inclusion of intracellular resistance index was slightly, but significantly (p 2max ( −1 ). In short, whole-body BIA marginally improves the accuracy of nonexercise V-dotO 2max prediction models and its advantage is most pronounced in individuals with particularly low V-dotO 2max

  6. Validity of bioelectrical impedance analysis to assess fat−free mass in head and neck cancer patients : an exploratory study

    NARCIS (Netherlands)

    Jager-Wittenaar, Harriët; Dijkstra, Pieter; Earthman, Carrie; Krijnen, Wim; Langendijk, Johannes A.; van der Laan, Bernard; Pruim, Jan; Roodenburg, Jan

    2013-01-01

    Assessment and monitoring of fat-free mass (FFM) is of clinical importance, because FFM is reflective of body cell mass, the total mass of protein-rich, metabolically active cells which is affected during malnutrition and therefore related to clinical outcome. Bioelectrical impedance analysis (BIA)

  7. Development of bioelectrical impedance analysis-based equations for estimation of body composition in postpartum rural Bangladeshi women.

    Science.gov (United States)

    Shaikh, Saijuddin; Schulze, Kerry J; Kurpad, Anura; Ali, Hasmot; Shamim, Abu Ahmed; Mehra, Sucheta; Wu, Lee S-F; Rashid, Mahbubar; Labrique, Alain B; Christian, Parul; West, Keith P

    2013-02-28

    Equations for predicting body composition from bioelectrical impedance analysis (BIA) parameters are age-, sex- and population-specific. Currently there are no equations applicable to women of reproductive age in rural South Asia. Hence, we developed equations for estimating total body water (TBW), fat-free mass (FFM) and fat mass in rural Bangladeshi women using BIA, with ²H₂O dilution as the criterion method. Women of reproductive age, participating in a community-based placebo-controlled trial of vitamin A or β-carotene supplementation, were enrolled at 19·7 (SD 9·3) weeks postpartum in a study to measure body composition by ²H₂O dilution and impedance at 50 kHz using multi-frequency BIA (n 147), and resistance at 50 kHz using single-frequency BIA (n 82). TBW (kg) by ²H2O dilution was used to derive prediction equations for body composition from BIA measures. The prediction equation was applied to resistance measures obtained at 13 weeks postpartum in a larger population of postpartum women (n 1020). TBW, FFM and fat were 22·6 (SD 2·7), 30·9 (SD 3·7) and 10·2 (SD 3·8) kg by ²H₂O dilution. Height²/impedance or height²/resistance and weight provided the best estimate of TBW, with adjusted R² 0·78 and 0·76, and with paired absolute differences in TBW of 0·02 (SD 1·33) and 0·00 (SD 1·28) kg, respectively, between BIA and ²H₂O. In the larger sample, values for TBW, FFM and fat were 23·8, 32·5 and 10·3 kg, respectively. BIA can be an important tool for assessing body composition in women of reproductive age in rural South Asia where poor maternal nutrition is common.

  8. Impedance analysis of subwoofer systems

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    The electrical impedance of four low-frequency loudspeaker systems is analyzed. The expression for this impedance is obtained directly from the acoustical analogous circuit. Formulas are derived for calculating the small-signal parameters from the frequencies of impedance minima and maxima of two

  9. The diagnostic accuracy of multi-frequency bioelectrical impedance analysis in diagnosing dehydration after stroke

    Science.gov (United States)

    Kafri, Mohannad W.; Myint, Phyo Kyaw; Doherty, Danielle; Wilson, Alexander Hugh; Potter, John F.; Hooper, Lee

    2013-01-01

    Background Non-invasive methods for detecting water-loss dehydration following acute stroke would be clinically useful. We evaluated the diagnostic accuracy of multi-frequency bioelectrical impedance analysis (MF-BIA) against reference standards serum osmolality and osmolarity. Material/Methods Patients admitted to an acute stroke unit were recruited. Blood samples for electrolytes and osmolality were taken within 20 minutes of MF-BIA. Total body water (TBW%), intracellular (ICW%) and extracellular water (ECW%), as percentages of total body weight, were calculated by MF-BIA equipment and from impedance measures using published equations for older people. These were compared to hydration status (based on serum osmolality and calculated osmolarity). The most promising Receiver Operating Characteristics curves were plotted. Results 27 stroke patients were recruited (mean age 71.3, SD10.7). Only a TBW% cut-off at 46% was consistent with current dehydration (serum osmolality >300 mOsm/kg) and TBW% at 47% impending dehydration (calculated osmolarity ≥295–300 mOsm/L) with sensitivity and specificity both >60%. Even here diagnostic accuracy of MF-BIA was poor, a third of those with dehydration were wrongly classified as hydrated and a third classified as dehydrated were well hydrated. Secondary analyses assessing diagnostic accuracy of TBW% for men and women separately, and using TBW as a percentage of lean body mass showed some promise, but did not provide diagnostically accurate measures across the population. Conclusions MF-BIA appears ineffective at diagnosing water-loss dehydration after stroke and cannot be recommended as a test for dehydration, but separating assessment by sex, and using TBW as a percentage of lean body weight may warrant further investigation. PMID:23839255

  10. Evaluation of body composition in COPD patients using multifrequency bioelectrical impedance analysis

    Directory of Open Access Journals (Sweden)

    de Blasio F

    2016-09-01

    Full Text Available Francesca de Blasio,1 Francesco de Blasio,2,3 Giulia Miracco Berlingieri,2 Andrea Bianco,3,4 Marta La Greca,1 Frits M E Franssen,5 Luca Scalfi1 1Department of Public Health, Medical School, “Federico II” University of Naples, 2Respiratory Medicine and Pulmonary Rehabilitation Section, Clinic Center, Private Hospital, Naples, 3Department of Medicine and Health Sciences “V Tiberio”, University of Molise, Campobasso, 4Department of Cardio-Thoracic and Respiratory Sciences, Second University of Naples, Naples, Italy; 5Department of Research and Education, CIRO, Horn, the NetherlandsBackground: Multifrequency bioelectrical impedance analysis (MF-BIA is a technique that measures body impedance (Z at different frequencies (5, 10, 50, 100, and 250 kHz. Body composition may be estimated using empirical equations, which include BIA variables or, alternatively, raw BIA data may provide direct information on water distribution and muscle quality.Objectives: To compare raw MF-BIA data between COPD patients and controls and to study their relationship with respiratory and functional parameters in COPD patients.Methods: MF-BIA was performed (Human Im-Touch analyzer in 212 COPD patients and 115 age- and BMI-matched controls. Fat-free mass (FFM and fat mass were estimated from BIA data, and low- to high-frequency (5 kHz/250 kHz impedance ratio was calculated. Physical fitness, lung function and respiratory muscle strength were also assessed in COPD patients.Results: After adjusting for age, weight, and body mass index, FFM and the 5/250 impedance ratio were lower in COPD patients (P<0.001 and were negatively affected by disease severity. In both male and female patients, the 5/250 impedance ratio was significantly correlated mainly with age (r=−0.316 and r=−0.346, respectively. Patients with a 5/250 impedance ratio below median value had lower handgrip strength (P<0.001, 6-minute walk distance (P<0.005, respiratory muscle strength (P<0.005, forced

  11. Bioelectrical impedance analysis for diagnosing sarcopenia and cachexia: what are we really estimating?

    Science.gov (United States)

    Gonzalez, Maria Cristina; Heymsfield, Steven B

    2017-04-01

    As reference methods are not available for identifying low skeletal muscle mass in clinical practice, the European Group on Sarcopenia in Older People the Asian Working Group for Sarcopenia and the International Consensus for Cancer Cachexia guidelines accept bioelectrical impedance analysis (BIA) as an option for sarcopenia and cachexia assessment. Using different BIA equations, several components that represent 'muscularity' can be assessed. Total skeletal muscle mass or appendicular skeletal muscle mass normalized in relation to height (skeletal muscle mass index or appendicular skeletal muscle index, respectively) is the most common term used in the consensus. These terms are similar, but they should not be used as synonymous. Both terms can be used to define sarcopenia, but adequate equations and cut-off values should be used according to the studied population. However, there is a disagreement between the sarcopenia definition assessed by using BIA from the European Group on Sarcopenia in Older People and Cachexia Consensus, and this can lead to an overestimation of sarcopenia and, consequently, cachexia. An effort should be made to standardize the terminology employed by the Societies to define low muscularity and sarcopenia by using BIA. Future validation studies may show the need for specific cut-off values for each population using this method. © 2017 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

  12. Hydration in advanced cancer: can bioelectrical impedance analysis improve the evidence base? A systematic review of the literature.

    Science.gov (United States)

    Nwosu, Amara Callistus; Mayland, Catriona R; Mason, Stephen R; Khodabukus, Andrew F; Varro, Andrea; Ellershaw, John E

    2013-09-01

    Decisions surrounding the administration of clinically assisted hydration to patients dying of cancer can be challenging because of the limited understanding of hydration in advanced cancer and a lack of evidence to guide health care professionals. Bioelectrical impedance analysis (BIA) has been used to assess hydration in various patient groupings, but evidence for its use in advanced cancer is limited. To critically appraise existing methods of hydration status assessment in advanced cancer and review the potential for BIA to assess hydration in advanced cancer. Searches were carried out in four electronic databases. A hand search of selected peer-reviewed journals and conference abstracts also was conducted. Studies reporting (de)hydration assessment (physical examination, biochemical measures, symptom assessment, and BIA) in patients with advanced cancer were included. The results highlight how clinical examination and biochemical tests are standard methods of assessing hydration, but limitations exist with these methods in advanced cancer. Furthermore, there is disagreement over the evidence for some commonly associated symptoms with dehydration in cancer. Although there are limitations with using BIA alone to assess hydration in advanced cancer, analysis of BIA raw measurements through the method of bioelectrical impedance vector analysis may have a role in this population. The benefits and burdens of providing clinically assisted hydration to patients dying of cancer are unclear. Bioelectrical impedance vector analysis shows promise as a hydration assessment tool but requires further study in advanced cancer. Innovative methodologies for research are required to add to the evidence base and ultimately improve the care for the dying. Copyright © 2013 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved.

  13. Accuracy of Bioelectrical Impedance Analysis in Estimated Longitudinal Fat-Free Mass Changes in Male Army Cadets.

    Science.gov (United States)

    Langer, Raquel D; Matias, Catarina N; Borges, Juliano H; Cirolini, Vagner X; Páscoa, Mauro A; Guerra-Júnior, Gil; Gonçalves, Ezequiel M

    2018-03-26

    Bioelectrical impedance analysis (BIA) is a practical and rapid method for making a longitudinal analysis of changes in body composition. However, most BIA validation studies have been performed in a clinical population and only at one moment, or point in time (cross-sectional study). The aim of this study is to investigate the accuracy of predictive equations based on BIA with regard to the changes in fat-free mass (FFM) in Brazilian male army cadets after 7 mo of military training. The values used were determined using dual-energy X-ray absorptiometry (DXA) as a reference method. The study included 310 male Brazilian Army cadets (aged 17-24 yr). FFM was measured using eight general predictive BIA equations, with one equation specifically applied to this population sample, and the values were compared with results obtained using DXA. The student's t-test, adjusted coefficient of determination (R2), standard error of estimation (SEE), Lin's approach, and the Bland-Altman test were used to determine the accuracy of the predictive BIA equations used to estimate FFM in this population and between the two moments (pre- and post-moment). The FFM measured using the nine predictive BIA equations, and determined using DXA at the post-moment, showed a significant increase when compared with the pre-moment (p FFM changes in the army cadets between the two moments in a very similar way to the reference method (DXA). However, only the one BIA equation specific to this population showed no significant differences in the FFM estimation between DXA at pre- and post-moment of military routine. All predictive BIA equations showed large limits of agreement using the Bland-Altman approach. The eight general predictive BIA equations used in this study were not found to be valid for analyzing the FFM changes in the Brazilian male army cadets, after a period of approximately 7 mo of military training. Although the BIA equation specific to this population is dependent on the amount of

  14. Application of bioelectrical impedance analysis in prediction of light kid carcass and muscle chemical composition.

    Science.gov (United States)

    Silva, S R; Afonso, J; Monteiro, A; Morais, R; Cabo, A; Batista, A C; Guedes, C M; Teixeira, A

    2018-06-01

    Carcass data were collected from 24 kids (average live weight of 12.5±5.5 kg; range 4.5 to 22.4 kg) of Jarmelista Portuguese native breed, to evaluate bioelectrical impedance analysis (BIA) as a technique for prediction of light kid carcass and muscle chemical composition. Resistance (Rs, Ω) and reactance (Xc, Ω), were measured in the cold carcasses with a single frequency bioelectrical impedance analyzer and, together with impedance (Z, Ω), two electrical volume measurements (VolA and VolB, cm2/Ω), carcass cold weight (CCW), carcass compactness and several carcass linear measurements were fitted as independent variables to predict carcass composition by stepwise regression analysis. The amount of variation explained by VolA and VolB only reached a significant level (Pcarcass fat weight (0.814⩽R 2⩽0.862; Pcarcass fat weight (combined with carcass length, CL; R 2=0.943; Pcarcass composition.

  15. Hand-to-Hand Model for Bioelectrical Impedance Analysis to Estimate Fat Free Mass in a Healthy Population.

    Science.gov (United States)

    Lu, Hsueh-Kuan; Chiang, Li-Ming; Chen, Yu-Yawn; Chuang, Chih-Lin; Chen, Kuen-Tsann; Dwyer, Gregory B; Hsu, Ying-Lin; Chen, Chun-Hao; Hsieh, Kuen-Chang

    2016-10-21

    This study aimed to establish a hand-to-hand (HH) model for bioelectrical impedance analysis (BIA) fat free mass (FFM) estimation by comparing with a standing position hand-to-foot (HF) BIA model and dual energy X-ray absorptiometry (DXA); we also verified the reliability of the newly developed model. A total of 704 healthy Chinese individuals (403 men and 301 women) participated. FFM (FFM DXA ) reference variables were measured using DXA and segmental BIA. Further, regression analysis, Bland-Altman plots, and cross-validation (2/3 participants as the modeling group, 1/3 as the validation group; three turns were repeated for validation grouping) were conducted to compare tests of agreement with FFM DXA reference variables. In male participants, the hand-to-hand BIA model estimation equation was calculated as follows: FFM m HH = 0.537 h²/Z HH - 0.126 year + 0.217 weight + 18.235 ( r ² = 0.919, standard estimate of error (SEE) = 2.164 kg, n = 269). The mean validated correlation coefficients and limits of agreement (LOAs) of the Bland-Altman analysis of the calculated values for FFM m HH and FFM DXA were 0.958 and -4.369-4.343 kg, respectively, for hand-to-foot BIA model measurements for men; the FFM (FFM m HF ) and FFM DXA were 0.958 and -4.356-4.375 kg, respectively. The hand-to-hand BIA model estimating equation for female participants was FFM F HH = 0.615 h²/Z HH - 0.144 year + 0.132 weight + 16.507 ( r ² = 0.870, SEE = 1.884 kg, n = 201); the three mean validated correlation coefficient and LOA for the hand-to-foot BIA model measurements for female participants (FFM F HH and FFM DXA ) were 0.929 and -3.880-3.886 kg, respectively. The FFM HF and FFM DXA were 0.942 and -3.511-3.489 kg, respectively. The results of both hand-to-hand and hand-to-foot BIA models demonstrated similar reliability, and the hand-to-hand BIA models are practical for assessing FFM.

  16. Hand-to-Hand Model for Bioelectrical Impedance Analysis to Estimate Fat Free Mass in a Healthy Population

    Directory of Open Access Journals (Sweden)

    Hsueh-Kuan Lu

    2016-10-01

    Full Text Available This study aimed to establish a hand-to-hand (HH model for bioelectrical impedance analysis (BIA fat free mass (FFM estimation by comparing with a standing position hand-to-foot (HF BIA model and dual energy X-ray absorptiometry (DXA; we also verified the reliability of the newly developed model. A total of 704 healthy Chinese individuals (403 men and 301 women participated. FFM (FFMDXA reference variables were measured using DXA and segmental BIA. Further, regression analysis, Bland–Altman plots, and cross-validation (2/3 participants as the modeling group, 1/3 as the validation group; three turns were repeated for validation grouping were conducted to compare tests of agreement with FFMDXA reference variables. In male participants, the hand-to-hand BIA model estimation equation was calculated as follows: FFMmHH = 0.537 h2/ZHH − 0.126 year + 0.217 weight + 18.235 (r2 = 0.919, standard estimate of error (SEE = 2.164 kg, n = 269. The mean validated correlation coefficients and limits of agreement (LOAs of the Bland–Altman analysis of the calculated values for FFMmHH and FFMDXA were 0.958 and −4.369–4.343 kg, respectively, for hand-to-foot BIA model measurements for men; the FFM (FFMmHF and FFMDXA were 0.958 and −4.356–4.375 kg, respectively. The hand-to-hand BIA model estimating equation for female participants was FFMFHH = 0.615 h2/ZHH − 0.144 year + 0.132 weight + 16.507 (r2 = 0.870, SEE = 1.884 kg, n = 201; the three mean validated correlation coefficient and LOA for the hand-to-foot BIA model measurements for female participants (FFMFHH and FFMDXA were 0.929 and −3.880–3.886 kg, respectively. The FFMHF and FFMDXA were 0.942 and −3.511–3.489 kg, respectively. The results of both hand-to-hand and hand-to-foot BIA models demonstrated similar reliability, and the hand-to-hand BIA models are practical for assessing FFM.

  17. Prediction of fat-free mass by bioelectrical impedance analysis in older adults from developing countries: a cross-validation study using the deuterium dilution method

    International Nuclear Information System (INIS)

    Mateo, H. Aleman; Romero, J. Esparza; Valencia, M.E.

    2010-01-01

    Objective: Several limitations of published bioelectrical impedance analysis (BIA) equations have been reported. The aims were to develop in a multiethnic, elderly population a new prediction equation and cross- validate it along with some published BIA equations for estimating fat-free mass using deuterium oxide dilution as the reference method. Design and setting: Cross-sectional study of elderly from five developing countries. Methods: Total body water (TBW) measured by deuterium dilution was used to determine fat-free mass (FFM) in 383 subjects. Anthropometric and BIA variables were also measured. Only 377 subjects were included for the analysis, randomly divided into development and cross-validation groups after stratified by gender. Stepwise model selection was used to generate the model and Bland Altman analysis was used to test agreement. Results: FFM = 2.95 - 3.89 (Gender) + 0.514 (Ht2/Z) + 0.090 (Waist) + 0.156 (Body weight). The model fit parameters were an R2, total F-Ratio, and the SEE of 0.88, 314.3, and 3.3, respectively. None of the published BIA equations met the criteria for agreement. The new BIA equation underestimated FFM by just 0.3 kg in the cross-validation sample. The mean of the difference between FFM by TBW and the new BIA equation were not significantly different; 95% of the differences were between the limits of agreement of -6.3 to 6.9 kg of FFM. There was no significant association between the mean of the differences and their averages (r= 0.008 and p= 0.2). Conclusions:This new BIA equation offers a valid option compared with some of the current published BIA equations to estimate FFM in elderly subjects from five developing countries. (Authors)

  18. The Impact of Feet Callosities, Arm Posture, and Usage of Electrolyte Wipes on Body Composition by Bioelectrical Impedance Analysis in Morbidly Obese Adults.

    Science.gov (United States)

    Roekenes, Jessica; Strømmen, Magnus; Kulseng, Bård; Martins, Catia

    2015-01-01

    This study evaluated the impact of feet callosities, arm posture, and use of electrolyte wipes on body composition measurements by bioelectrical impedance analysis (BIA) in morbidly obese adults. 36 morbidly obese patients (13 males, aged 28-70 years, BMI 41.6 ± 4.3 kg/m2) with moderate/severe feet callosities participated in this study. Body composition (percent body fat (%BF)) was measured while fasting using multi-frequency BIA (InBody 720®), before and after removal of callosities, with and without InBody® electrolyte wipes and custom-built auxiliary pads (to assess arm posture impact). Results from BIA were compared to air displacement plethysmography (ADP, BodPod®). Median %BF was significantly higher with auxiliary pads than without (50.1 (interquartile range 8.2) vs. 49.3 (interquartile range 9.1); p interquartile range 9.1) vs. 50.0 (interquartile range 7.9); NS) or use of wipes (49.6 (interquartile range 8.5) vs. 49.3 (interquartile range 9.1); NS). No differences in %BF were found between BIA and ADP (49.1 (IQR: 8.9) vs. 49.3 (IQR: 9.1); NS). Arm posture has a significant impact on %BF assessed by BIA, contrary to the presence of feet callosities and use of electrolyte wipes. Arm posture standardization during BIA for body composition assessment is, therefore, recommended. © 2015 S. Karger GmbH, Freiburg.

  19. Estimation of prevalence of sarcopenia by using a new bioelectrical impedance analysis in Chinese community-dwelling elderly people.

    Science.gov (United States)

    Wang, Hui; Hai, Shan; Cao, Li; Zhou, Jianghua; Liu, Ping; Dong, Bi-Rong

    2016-12-28

    The aim of the present study was to validate the usefulness of the new octapolar multifrequency bioelectrical impedance analysis (BIA) for assessment of appendicular skeletal muscle mass (ASM) by comparing it with that of dual-energy X-ray absorptiometry (DXA) and to investigate the prevalence of sarcopenia in Chinese community-dwelling elderly according to Asian Working Group for Sarcopenia (AWGS) definition. A cross-sectional study was conducted in communities of Chengdu, China. A total of 944 community-dwelling elderly adults aged ≥60 years were included. ASM was measured by using DXA as a criterion method to validate a standing eight-electrode multifrequency BIA (InBody 720), followed by a further estimation of the prevalence of sarcopenia according the AWGS definition. In the Bland-Altman analysis, no significant difference was found between DXA and BIA based on the ASM measurements. The prevalence of AWGS-defined sarcopenia was 12.5% in the elderly women and 8.2% in the elderly men. BIA is suitable for body composition monitoring (ASM) in elderly Chinese as a fast, noninvasive, and convenient method; therefore, it may be a better choice in large epidemiological studies in the Chinese population. The prevalence of AWGS-defined sarcopenia was approximately 10.4% and increased with age in the Chinese community-dwelling elderly in this study.

  20. Bioelectrical impedance vector analysis (BIVA for measuring the hydration status in young elite synchronized swimmers.

    Directory of Open Access Journals (Sweden)

    Marta Carrasco-Marginet

    Full Text Available The assessment of body hydration is a complex process, and no measurement is valid for all situations. Bioelectrical impedance vector analysis (BIVA has emerged as a relatively novel technique for assessing hydration status in sports. We applied BIVA a to determine hydration changes evoked by an intense synchronized swimming (SS training session; b to characterize the sample of young elite swimmers in relation with a nonathletic reference population; and c to generate its 50%, 75% and 95% percentiles of the bioelectrical variables.Forty-nine elite SS female swimmers of two age categories, comen (Co: 13.9 ± 0.9 years, n = 34 and junior (Jr: 16.3 ± 0.6 years, n = 15, performed a long, high intensity training session. Body mass (BM and bioelectrical variables (R, resistance; Xc, reactance; PA, phase angle; and Z, impedance module were assessed pre- and post-training. BIVA was used to characterize 1 the distribution pattern of the bioelectrical vector (BIA vector for both age groups, and 2 pre- to post-training BIA vector migration. Bioelectrical variables were also correlated with BM change values.Most swimmers were mostly located outside the 75% and some beyond the 95% percentile of the bioelectrical tolerance ellipses of the general population. The BIA vector showed statistically significant differences in both Co (T2 = 134.7, p = 0.0001 and Jr (T2 = 126.2, p < 0.001. Both groups were also bioelectrically different (T2 = 17.6, p < 0.001. After the training session, a decrease in BM (p = 0.0001 and an increase in BIA variables (p = 0.01 was observed. BIVA also showed a significant pre-post vector migration both in Co (T2 = 82.1; p < 0.001 and Jr (T2 = 41.8; p < 0.001. No correlations were observed between BM changes and bioelectrical variables.BIVA showed specific bioelectrical characteristics in young elite SS athletes. Considering the decrease in BM and the migration of the BIA vector, we conclude that the homeostatic hydration status of these

  1. Feasibility of bioelectrical impedance analysis in persons with severe intellectual and visual disabilities.

    Science.gov (United States)

    Havinga-Top, A M; Waninge, A; van der Schans, C P; Jager-Wittenaar, H

    2015-12-01

    Body composition measurements provide important information about physical fitness and nutritional status. People with severe intellectual and visual disabilities (SIVD) have an increased risk for altered body composition. Bioelectrical impedance analysis (BIA) has been evidenced as a reliable and non-invasive method to asses body composition in healthy persons and various patient populations; however, currently, there is no feasible method available to determine body composition in people with SIVD. In this study, therefore, we aimed to assess the feasibility of BIA measurements in persons with SIVD. In 33 participants with SIVD and Gross Motor Functioning Classification System (GMFCS) Scale I, II, III, or IV, two BIA measurements were sequentially performed employing Resistance and Reactance in Ohm and fat-free mass (FFM) in kg as outcome variables, utilizing the Bodystat(®) QuadScan 4000. Feasibility was considered sufficient if ≥ 80% of the first measurement was performed successfully. Agreement between two repeated measurements was determined by using the paired t-test and Intraclass Correlation Coefficient (ICC; two way random, absolute agreement). Bland-Altman analyses were utilized to determine limits of agreement (LOAs) and systematic error. Agreement was considered acceptable if LOAs were feasible in persons with SIVD. Although these results require confirmation in a more extensive sample of persons with SIVD, the findings of this study are an important first step in the assessment of applicability of BIA measurements for non-invasive monitoring of physical fitness and nutritional status of persons with SIVD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Lipid and moisture content modeling of amphidromous Dolly Varden using bioelectrical impedance analysis

    Science.gov (United States)

    Stolarski, J.T.; Margraf, F.J.; Carlson, J.G.; Sutton, T.M.

    2014-01-01

    The physiological well-being or condition of fish is most commonly estimated from aspects of individual morphology. However, these metrics may be only weakly correlated with nutritional reserves stored as lipid, the primary form of accumulated energy in fish. We constructed and evaluated bioelectrical impedance analysis (BIA) models as an alternative method of assessing condition in amphidromous Dolly Varden Salvelinus malma collected from nearshore estuarine and lotic habitats of the Alaskan Arctic. Data on electrical resistance and reactance were collected from the lateral and ventral surfaces of 192 fish, and whole-body percent lipid and moisture content were determined using standard laboratory methods. Significant inverse relationships between temperature and resistance and reactance prompted the standardization of these data to a constant temperature using corrective equations developed herein. No significant differences in resistance or reactance were detected among spawning and nonspawning females after accounting for covariates, suggesting that electrical pathways do not intersect the gonads. Best-fit BIA models incorporating electrical variables calculated from the lateral and ventral surfaces produced the strongest associations between observed and model-predicted estimates of proximate content. These models explained between 6% and 20% more of the variability in laboratory-derived estimates of proximate content than models developed from single-surface BIA data and 32% more than models containing only length and weight data. While additional research is required to address the potential effects of methodological variation, bioelectrical impedance analysis shows promise as a way to provide high-quality, minimally invasive estimates of Dolly Varden lipid or moisture content in the field with only small increases in handling time.

  3. The comparative evaluation of patients′ body dry weight under hemodialysis using two methods: Bioelectrical impedance analysis and conventional method

    Directory of Open Access Journals (Sweden)

    Neda Alijanian

    2012-01-01

    Full Text Available Background: Dry weight (DW is an important concept related to patients undergoing hemodialysis. Conventional method seems to be time consuming and operator dependent. Bio impedance analysis (BIA is a new and simple method reported to be an accurate way for estimating DW. In this study, we aimed to compare the conventional estimation of DW with measuring DW by BIA. Materials and Methods: This study involved 130 uremic patients, performed in Isfahan, Iran. DW was calculated by both conventional (CDW and BIA (BIADW method and results were compared based on different grouping factors including sex, underlying cause of renal failure (RF (diabetic RF and non-diabetic RF, body mass index (BMI status, and sessions of hemodialysis. We also calculated the difference between DWs of 2 methods (DW diff = CDW-BIADW. Results: The mean of BIADW was significantly lower than CDW (57.20 ± 1.82 vs 59.36 ± 1.77, P value < 0.001. After grouping cases according to the underlying cause, BMI, sex, and dialysis sessions BIADW was significantly lower than CDW. Conclusion: Based on the combination of problems with CDW measurement which are corrected by BIA, and more clinical reliability of CDW, we concluded that although conventional method is a time-consuming and operator-dependent way to assess DW, DW could be estimated by combining both of these methods by finding the mathematic correlation between these methods.

  4. Study of Body Composition by Impedance Analysis

    Science.gov (United States)

    González-Solís, J. L.; Vargas-Luna, M.; Sosa-Aquino, M.; Bernal-Alvarado, J.; Gutiérrez-Juárez, G.; Huerta-Franco, R.; Sanchis-Sabater, A.

    2002-08-01

    This work presents a set of impedance measurements and preliminary results on the analysis of body composition using impedance spectroscopy. This study is made using a pork meat sample and spectra from fat and flesh region were independently obtained using the same electrodes array. From these measurements, and theoretical considerations, it is possible to explain the behavior of the composite sample flesh-fat-flesh and, fitting the electrical parameters of the model, it shows the plausibility of a physical and quantitative application to human corporal composition.

  5. Wavelet analysis of the impedance cardiogram waveforms

    Science.gov (United States)

    Podtaev, S.; Stepanov, R.; Dumler, A.; Chugainov, S.; Tziberkin, K.

    2012-12-01

    Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt)max) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.

  6. Wavelet analysis of the impedance cardiogram waveforms

    International Nuclear Information System (INIS)

    Podtaev, S; Stepanov, R; Dumler, A; Chugainov, S; Tziberkin, K

    2012-01-01

    Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt) max ) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.

  7. Impedance analysis on organic ultrathin layers

    Energy Technology Data Exchange (ETDEWEB)

    Bom, Sidhant; Wagner, Veit [Jacobs University Bremen, School of Engineering and Science, Campus Ring 8, 28759 Bremen (Germany)

    2008-07-01

    Impedance spectroscopy is a standard technique for thin film analysis to obtain important information as thicknesses, diffusion properties of mobile ions and leakage currents. The measured electrical impedance of a sample is modeled by a physical equivalent circuit of resistors and capacitors. In the present work this information is obtained as a function of frequency also for ultrathin organic layers in the monolayer regime. A series of semiconducting and insulating polymers (regioregular poly-3-hexylthiophene (rr-P3HT), polymethylmethacrylate (PMMA)) and self assembled monolayers (octadecyltrichlorosilane (OTS), hexamethyldisilazane (HMDS), thiolated phospholipids) were deposited either on highly n-doped silicon wafers or on gold surfaces. E.g. ultrathin layers were obtained by dip coating a silicon wafer in rr-P3HT solution in chloroform. The thickness of 2 nm determined for this system by impedance measurement agrees well with the atomic force microscopy analysis and corresponds to a single layer of polymer chains. The leakage current is seen as an ohmic contribution at low frequencies and allows a systematic optimization of process parameters. In summary, impedance spectroscopy allows very fast and convenient analysis of thin organic layers even down to the monolayer regime.

  8. Prevalence of malnutrition and validation of bioelectrical impedance analysis for the assessment of body composition in patients with systemic sclerosis.

    Science.gov (United States)

    Spanjer, Moon J; Bultink, Irene E M; de van der Schueren, Marian A E; Voskuyl, Alexandre E

    2017-06-01

    The aims were to assess the prevalence of malnutrition and to validate bioelectrical impedance analysis (BIA) against whole-body DXA for the assessment of body composition in patients with SSc. Malnutrition was defined as BMI 10% in combination with a fat-free mass index (FFMI) 70 years). Body composition was assessed in 72 patients with whole-body DXA (Hologic, Discovery A) and BIA (Bodystat Quadscan 400). The manufacturer's equation and the Geneva equation were used to estimate FFM and fat mass. The agreement between BIA and whole-body DXA was assessed with Bland-Altman analysis and intraclass correlation coefficient. Malnutrition was found in 8.3% (n = 6) and low FFMI in 20.8% (n = 15) of patients. The mean difference in FFM between BIA and DXA applying the Geneva equation was 0.02 ( s . d . 2.4) kg, intraclass correlation coefficient 0.97 (95% CI: 0.95, 0.98). Limits of agreement were ±4.6 kg. The manufacturer's equation was less adequate to predict FFM. This study shows a relatively low prevalence of malnutrition in comparison with other studies, but a high prevalence of low FFMI, underlining the necessity of measuring body composition in SSc patients with a standardized and validated method. A good validity of BIA in determining FFM was found at a group level, while at an individual level the FFM may vary by 4.6 kg. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  9. Feasibility and acceptability of a self-measurement using a portable bioelectrical impedance analysis, by the patient with chronic heart failure, in acute decompensated heart failure.

    Science.gov (United States)

    Huguel, Benjamin; Vaugrenard, Thibaud; Saby, Ludivine; Benhamou, Lionel; Arméro, Sébastien; Camilleri, Élise; Langar, Aida; Alitta, Quentin; Grino, Michel; Retornaz, Frédérique

    2018-06-01

    Chronic heart failure (CHF) is a major public health matter. Mainly affecting the elderly, it is responsible for a high rate of hospitalization due to the frequency of acute heart failure (ADHF). This represents a disabling pathology for the patient and very costly for the health care system. Our study is designed to assess a connected and portable bioelectrical impedance analysis (BIA) that could reduce these hospitalizations by preventing early ADHF. This prospective study included patients hospitalized in cardiology for ADHF. Patients achieved 3 self-measurements using the BIA during their hospitalization and answered a questionnaire evaluating the acceptability of this self-measurement. The results of these measures were compared with the clinical, biological and echocardiographic criteria of patients at the same time. Twenty-three patients were included, the self-measurement during the overall duration of the hospitalization was conducted autonomously by more than 80% of the patients. The acceptability (90%) for the use of the portable BIA was excellent. Some correlations were statistically significant, such as the total water difference to the weight difference (p=0.001). There were common trends between the variation of impedance analysis measures and other evaluation criteria. The feasibility and acceptability of a self-measurement of bioelectrical impedance analysis by the patient in AHF opens up major prospects in the management of monitoring patients in CHF. The interest of this tool is the prevention of ADHF leading to hospitalization or re-hospitalizations now requires to be presented by new studies.

  10. Fat-free mass prediction equations for bioelectric impedance analysis compared to dual energy X-ray absorptiometry in obese adolescents: a validation study.

    Science.gov (United States)

    Hofsteenge, Geesje H; Chinapaw, Mai J M; Weijs, Peter J M

    2015-10-15

    In clinical practice, patient friendly methods to assess body composition in obese adolescents are needed. Therefore, the bioelectrical impedance analysis (BIA) related fat-free mass (FFM) prediction equations (FFM-BIA) were evaluated in obese adolescents (age 11-18 years) compared to FFM measured by dual-energy x-ray absorptiometry (FFM-DXA) and a new population specific FFM-BIA equation is developed. After an overnight fast, the subjects attended the outpatient clinic. After measuring height and weight, a full body scan by dual-energy x-ray absorptiometry (DXA) and a BIA measurement was performed. Thirteen predictive FFM-BIA equations based on weight, height, age, resistance, reactance and/or impedance were systematically selected and compared to FFM-DXA. Accuracy of FFM-BIA equations was evaluated by the percentage adolescents predicted within 5% of FFM-DXA measured, the mean percentage difference between predicted and measured values (bias) and the Root Mean Squared prediction Error (RMSE). Multiple linear regression was conducted to develop a new BIA equation. Validation was based on 103 adolescents (60% girls), age 14.5 (sd1.7) years, weight 94.1 (sd15.6) kg and FFM-DXA of 56.1 (sd9.8) kg. The percentage accurate estimations varied between equations from 0 to 68%; bias ranged from -29.3 to +36.3% and RMSE ranged from 2.8 to 12.4 kg. An alternative prediction equation was developed: FFM = 0.527 * H(cm)(2)/Imp + 0.306 * weight - 1.862 (R(2) = 0.92, SEE = 2.85 kg). Percentage accurate prediction was 76%. Compared to DXA, the Gray equation underestimated the FFM with 0.4 kg (55.7 ± 8.3), had an RMSE of 3.2 kg, 63% accurate prediction and the smallest bias of (-0.1%). When split by sex, the Gray equation had the narrowest range in accurate predictions, bias, and RMSE. For the assessment of FFM with BIA, the Gray-FFM equation appears to be the most accurate, but 63% is still not at an acceptable accuracy level for obese adolescents. The new equation appears to

  11. Assessment of fat-free mass from bioelectrical impedance analysis in obese women with Prader-Willi syndrome.

    Science.gov (United States)

    Bedogni, Giorgio; Grugni, Graziano; Tringali, Gabriella; Agosti, Fiorenza; Sartorio, Alessandro

    2015-01-01

    Fat-free mass (FFM) is lower in obese subjects with Prader-Willi syndrome (PWS) than in obese subjects without PWS. FFM prediction equations developed in non-PWS subjects may, thus, not work in PWS subjects. To test whether the estimation of FFM from bioelectrical impedance analysis (BIA) in PWS subjects requires population-specific equations. Using dual-energy X-ray absorptiometry, this study measured FFM in 27 PWS and 56 non-PWS obese women and evaluated its association with the impedance index at 50 kHz (ZI50), i.e. the ratio between squared height and whole-body impedance at 50 kHz. At the same level of ZI50, PWS women had a lower FFM than non-PWS women. However, when PWS-specific equations were used, FFM was accurately estimated at the population level. An equation employing a dummy variable coding for PWS status was able to explain 85% of the variance of FFM with a root mean squared error of 3.3 kg in the pooled sample (n = 83). Population-specific equations are needed to estimate FFM from BIA in obese PWS women.

  12. [Evaluation of nutritional Status in lung cancer using bio electrical impedance analysis and mini nutritional assessment].

    Science.gov (United States)

    Daghfous, Hafaoua; El Ayeb, Wejdène; Alouane, Leila; Tritar, Fatma

    2014-12-01

    Malnutrition and cachexia were a frequent problem in lung cancer and increases the risks of morbidity and mortality in these patients. Bioelectrical impedance analysis (BIA) is easy, non-invasive and reproducible method that can be performed. Evaluate nutritional status in patients with primary lung cancer by Mini Nutritional Assessment (MNA), BIA and anthropometric values (weight, arm and calf circumferences) and correlate the nutritional parameters to severity of cancer and histopathology. The nutritional status of 73 cases of primary lung cancer was evaluated by anthropometric parameters, MNA test and impedencemetrie Results: According to body mass index (BMI), malnutrition, overweight and obesity were noted in 34,2%, 13,7% and 5,5%. According to BMI, free-fat mass index (FFMI) and fat mass index (FMI), the investigations occurred malnutrition and depletion of muscle in respectively 19,2% and 23,3% of cases. Fat depletion was noted in 21,9%. Overweight and obesity were detected in 6,8% and 5,5% of cases. Assessment by MNA, revealed that 28,7% of patients were already malnourished and 49,3% of patients were at risk of malnutrition. A significant correlation existed between the score of MNA and arm and calf circumferences, FFMI and FMI. FMI was significantly lower in group of patients with small lung carcinoma. Only FFMI allows early detection of malnutrition in cancer patients overestimated by measuring BMI and arm circumference was the better indicator of depletion of muscle.

  13. The additional value of bioelectrical impedance analysis-derived muscle mass as a screening tool in geriatric assessment for fall prevention.

    Science.gov (United States)

    Van Puyenbroeck, Karolien; Roelandts, Lieven; Van Deun, Thomas; Van Royen, Paul; Verhoeven, Veronique

    2012-01-01

    The decline in skeletal muscle in old age is a factor in the development of functional limitations. The objective of this study was to assess if there is a correlation between muscle mass based on bioelectrical impedance analysis (BIA) detection and the fall incidence in nursing home residents and to examine the risk factors for falling in nursing home residents. This prospective cohort study was part of a longitudinal study on nutritional issues in 52 nursing homes in Antwerp (Belgium) from October 2007 to April 2008. Two hundred and seventy-six people aged 65 years and older were included. Each subject was assessed with BIA, the timed get-up-and-go test, the Katz score, the Mini Nutritional Assessment - Short Form and the 36-Item Short Form Health Survey. The primary outcome parameter was fall incidence during the study. The prevalence of sarcopenia varied from 24.3 to 81.5% depending on which definition was used. No association was found between BIA-derived muscle mass and fall incidence. Logistic regression analysis showed that gait speed (odds ratio 1.029; p = 0.003) and mental health (odds ratio 0.981; p = 0.015) are significantly associated with fall incidence in nursing homes. A receiver operating characteristic curve showed that none of the BIA-derived muscle parameters are good predictors of the risk of falling. This study shows that there is no association between sarcopenia based on BIA and fall incidence and that BIA-derived muscle mass has no additional value in predicting fall incidents compared to the timed get-up-and-go test. Copyright © 2012 S. Karger AG, Basel.

  14. Impedance Based Analysis and Design of Harmonic Resonant Controller for a Wide Range of Grid Impedance

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede

    2014-01-01

    This paper investigates the effect of grid impedance variation on harmonic resonant current controllers for gridconnected voltage source converters by means of impedance-based analysis. It reveals that the negative harmonic resistances tend to be derived from harmonic resonant controllers...... in the closed-loop output admittance of converter. Such negative resistances may interact with the grid impedance resulting in steady state error or unstable harmonic compensation. To deal with this problem, a design guideline for harmonic resonant controllers under a wide range of grid impedance is proposed...

  15. Impedance analysis of acupuncture points and pathways

    International Nuclear Information System (INIS)

    Teplan, Michal; Kukucka, Marek; Ondrejkovicová, Alena

    2011-01-01

    Investigation of impedance characteristics of acupuncture points from acoustic to radio frequency range is addressed. Discernment and localization of acupuncture points in initial single subject study was unsuccessfully attempted by impedance map technique. Vector impedance analyses determined possible resonant zones in MHz region.

  16. Making the invisible visible: bioelectrical impedance analysis demonstrates unfavourable body composition in rheumatoid arthritis patients in clinical practice.

    Science.gov (United States)

    Konijn, N P C; van Tuyl, L H D; Bultink, I E M; Lems, W F; Earthman, C P; van Bokhorst-de van der Schueren, M A E

    2014-01-01

    To examine differences between the assessment of body composition by body mass index (BMI) and bioelectrical impedance analysis (BIA) in patients with rheumatoid arthritis (RA). The body composition of RA patients was assessed during their visit to the outpatient department of a Dutch academic hospital using BMI, fat-free mass index (FFMI), and fat mass index (FMI). FFMI and FMI were determined by single-frequency BIA. Sixty-five consecutive RA patients (83% women, mean age 58 years, median disease duration 7 years) with moderately active disease [mean Disease Activity Score using 28 joint counts (DAS28) = 3.40; mean Rheumatoid Arthritis Disease Activity Index (RADAI) score = 3.49] and moderate disability [mean Health Assessment Questionnaire (HAQ) score = 0.87] were included. Based on BMI, 2% of our study population were underweight, 45% had a healthy body composition, and 54% were overweight or obese. Based on BIA, 18% of the patients showed a low FFMI and 74% had a high or very high FMI. Low FFMI was found in 44% of the women with a normal BMI, and high FMI was found in 40% of the women and 75% of the men with a normal BMI. A high frequency of unfavourable body composition, predominantly reduced FFMI and elevated FMI, was found in a cohort of RA patients with moderately active disease, turning BMI into an unreliable method for assessment of body composition in RA. BIA, however, might be the preferred method to assess FFMI and FMI in RA patients in clinical practice, as it is easy to use and relatively inexpensive.

  17. MVAC Submarine cable, impedance measurements and analysis

    DEFF Research Database (Denmark)

    Arentsen, Martin Trolle; Expethit, Adrian; Pedersen, Morten Virklund

    2017-01-01

    influence the losses. Secondly, cable parameters such as component impedances, positive-, zero-sequence impedances and losses are measured for varying currents and frequencies. Zero sequence is measured for two setups, one with armour grounded, and with armour open to match CIGREs formula assumption......-sequence impedance is found between the measurements and the CIGRÉ formulas. It is concluded that the formulas are not accurate for the specific cable under test....

  18. Validation of two portable bioelectrical impedance analyses for the assessment of body composition in school age children.

    Directory of Open Access Journals (Sweden)

    Li-Wen Lee

    Full Text Available Bioelectrical impedance analysis (BIA is a convenient and child-friendly method for longitudinal analysis of changes in body composition. However, most validation studies of BIA have been performed on adult Caucasians. The present cross-sectional study investigated the validity of two portable BIA devices, the Inbody 230 (BIA8MF and the Tanita BC-418 (BIA8SF, in healthy Taiwanese children.Children aged 7-12 years (72 boys and 78 girls were recruited. Body composition was measured by the BIA8SF and the BIA8MF. Dual X-ray absorptiometry (DXA was used as the reference method.There were strong linear correlations in body composition measurements between the BIA8SF and DXA and between the BIA8MF and DXA. Both BIAs underestimated fat mass (FM and percentage body fat (%BF relative to DXA in both genders The degree of agreement in lean body mass (LBM, FM, and %BF estimates was higher between BIA8MF and DXA than between BIA8SF and DXA. The Lin's concordance correlation coefficient (ρc for LBM8MF met the criteria of substantial to perfect agreement whereas the ρc for FM8MF met the criteria of fair to substantial agreement. Bland-Altman analysis showed a clinically acceptable agreement between LBM measures by BIA8MF and DXA. The limit of agreement in %BF estimation by BIA and DXA were wide and the errors were clinically important. For the estimation of ALM, BIA8SF and BIA8MF both provided poor accuracy.For all children, LBM measures were precise and accurate using the BIA8MF whereas clinically significant errors occurred in FM and %BF estimates. Both BIAs underestimated FM and %BF in children. Thus, the body composition results obtained using the inbuilt equations of the BIA8SF and BIA8MF should be interpreted with caution, and high quality validation studies for specific subgroups of children are required prior to field research.

  19. Comparison of Body Fat Results from 4 Bioelectrical Impedance Analysis Devices vs. Air Displacement Plethysmography in American Adolescent Wrestlers

    Directory of Open Access Journals (Sweden)

    Melissa M. Montgomery

    2017-10-01

    Full Text Available Background: Accurate and accessible methods of body composition are necessary to ensure health and safety of wrestlers during competition. The most valid and reliable instruments are expensive and relatively inaccessible to high school wrestlers; therefore, more practical technology is needed. Objective: To compare body fat percentage (BF% results from 4 bioelectrical impedance analysis (BIA devices to those from air displacement plethysmography (ADP in adolescent wrestlers. Methodology: 134 adolescent male and female wrestlers (1.72±0.9 m, 66.8±14.3 kg, 15.6±1.1 yrs. were tested for hydration and then completed 4 body composition tests with different BIA devices and one with Bod Pod. Relative and absolute agreement were assessed between each BIA device and ADP on a single day. Results: When compared with ADP, all devices demonstrated excellent reliability (ICC (2,1 range: 0.88-0.94, but questionable measurement error (SEM range: 2.3-3.6 %BF. Bland-Altman plots revealed that each bioelectrical impedance device we tested over-estimated body fat percent in high school wrestlers (range: 0.8-3.6 %BF and demonstrated wide 95% limits of agreement (range: 15.0-20.8 %BF compared to ADP. Conclusions: The devices investigated demonstrated reasonable measurement accuracy. However, wide margins of error of each device were noted. Caution should be taken when assessing adolescent wrestlers with lower amounts of body fat, as it may result in failing to identify those who do not meet the minimum body fat percentage for competition. The governing bodies should use the research data in the decision-making process regarding appropriate devices for use in their weight management programs.

  20. Utility of Volume Assessment Using Bioelectrical Impedance Analysis in Critically Ill Patients Receiving Continuous Renal Replacement Therapy: A Prospective Observational Study

    Directory of Open Access Journals (Sweden)

    Ki Hyun Park

    2017-08-01

    Full Text Available Background Fluid overload prior to continuous renal replacement therapy (CRRT is an important prognostic factor. Thus, precise evaluation of fluid status is necessary to treat such patients. In this study, we investigated whether fluid assessment using bioelectrical impedance analysis (BIA can predict outcomes in critically ill patients requiring CRRT. Methods A prospective observational study was performed in patients who were admitted to the intensive care unit and who required CRRT. BIA was conducted before CRRT; then, the ratio of extracellular water to total body water (ECW/TBW was derived to estimate volume status. Results A total of 31 patients treated with CRRT were included. There were 18 men (58.1%, and the median age was 67 years (interquartile range, 51 to 78 years. Fourteen patients (45.2% died within 28 days after CRRT initiation. Patients were divided into 16 with ECW/TBW ≥0.41 and 15 with ECW/TBW <0.41. Survival rate within 28 days was different between the two groups (P = 0.044. Cox regression analysis revealed a relationship between ECW/TBW ≥0.41 and 28-day mortality, but it was not statistically significant (hazard ratio, 3.0; 95% confidence interval, 0.9 to 9.8; P = 0.061. Lastly, the area under the curve of ECW/TBW for 28-day mortality was analyzed. The area under the curve of ECW/TBW was 0.73 (95% confidence interval, 0.54 to 0.92, and this was significant (P = 0.037. Conclusions Fluid status can be assessed using BIA in critically ill patients requiring CRRT, and BIA can predict mortality. Further large trials are needed to confirm the usefulness of BIA in critically ill patients.

  1. Modeling and Grid impedance Variation Analysis of Parallel Connected Grid Connected Inverter based on Impedance Based Harmonic Analysis

    DEFF Research Database (Denmark)

    Kwon, JunBum; Wang, Xiongfei; Bak, Claus Leth

    2014-01-01

    This paper addresses the harmonic compensation error problem existing with parallel connected inverter in the same grid interface conditions by means of impedance-based analysis and modeling. Unlike the single grid connected inverter, it is found that multiple parallel connected inverters and grid...... impedance can make influence to each other if they each have a harmonic compensation function. The analysis method proposed in this paper is based on the relationship between the overall output impedance and input impedance of parallel connected inverter, where controller gain design method, which can...

  2. Impedance Analysis of SOGI-FLL-Based Grid Synchronization

    DEFF Research Database (Denmark)

    Yi, Hao; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    The latest research has pointed out that the Phase-Locked Loop (PLL) plays an important role in shaping the impedance of grid-connected converters, yet most of the works so far merely focus on the synchronous reference-frame PLL. Alternatively, this letter presents the impedance analysis...

  3. Analysis and design of complex impedance transforming marchand baluns

    DEFF Research Database (Denmark)

    Michaelsen, Rasmus Schandorph; Johansen, Tom Keinicke; Tamborg, Kjeld M.

    2014-01-01

    A new type of Marchand balun is presented in this paper, which has the property of complex impedance transformation. To allow the Marchand balun to transform between arbitrary complex impedances, three reactances should be added to the circuit. A detailed analysis of the circuit gives the governing...

  4. BMI or BIA: Is Body Mass Index or Body Fat Mass a Better Predictor of Cardiovascular Risk in Overweight or Obese Children and Adolescents? A German/Austrian/Swiss Multicenter APV Analysis of 3,327 Children and Adolescents.

    Science.gov (United States)

    Bohn, Barbara; Müller, Manfred James; Simic-Schleicher, Gunter; Kiess, Wieland; Siegfried, Wolfgang; Oelert, Monika; Tuschy, Sabine; Berghem, Stefan; Holl, Reinhard W

    2015-01-01

    Body fat (BF) percentiles for German children and adolescents have recently been published. This study aims to evaluate the association between bioelectrical impedance analysis (BIA)-derived BF and cardiovascular risk factors and to investigate whether BF is better suited than BMI in children and adolescents. Data of 3,327 children and adolescents (BMI > 90th percentile) were included. Spearman's correlation and receiver operating characteristics (ROCs) were applied determining the associations between BMI or BF and cardiovascular risk factors (hypertension, dyslipidemia, elevated liver enzymes, abnormal carbohydrate metabolism). Area under the curve (AUC) was calculated to predict cardiovascular risk factors. A significant association between both obesity indices and hypertension was present (all p risk factors. BF significantly predicted hypertension (AUC = 0.61), decreased HDL-cholesterol (AUC = 0.58), elevated LDL-cholesterol (AUC = 0.59), elevated liver enzymes (AUC = 0.61) (all p risk factors, no significant differences between BMI and BF were observed. BIA-derived BF was not superior to BMI to predict cardiovascular risk factors in overweight or obese children and adolescents.

  5. The novel application of artificial neural network on bioelectrical impedance analysis to assess the body composition in elderly

    Science.gov (United States)

    2013-01-01

    Background This study aims to improve accuracy of Bioelectrical Impedance Analysis (BIA) prediction equations for estimating fat free mass (FFM) of the elderly by using non-linear Back Propagation Artificial Neural Network (BP-ANN) model and to compare the predictive accuracy with the linear regression model by using energy dual X-ray absorptiometry (DXA) as reference method. Methods A total of 88 Taiwanese elderly adults were recruited in this study as subjects. Linear regression equations and BP-ANN prediction equation were developed using impedances and other anthropometrics for predicting the reference FFM measured by DXA (FFMDXA) in 36 male and 26 female Taiwanese elderly adults. The FFM estimated by BIA prediction equations using traditional linear regression model (FFMLR) and BP-ANN model (FFMANN) were compared to the FFMDXA. The measuring results of an additional 26 elderly adults were used to validate than accuracy of the predictive models. Results The results showed the significant predictors were impedance, gender, age, height and weight in developed FFMLR linear model (LR) for predicting FFM (coefficient of determination, r2 = 0.940; standard error of estimate (SEE) = 2.729 kg; root mean square error (RMSE) = 2.571kg, P < 0.001). The above predictors were set as the variables of the input layer by using five neurons in the BP-ANN model (r2 = 0.987 with a SD = 1.192 kg and relatively lower RMSE = 1.183 kg), which had greater (improved) accuracy for estimating FFM when compared with linear model. The results showed a better agreement existed between FFMANN and FFMDXA than that between FFMLR and FFMDXA. Conclusion When compared the performance of developed prediction equations for estimating reference FFMDXA, the linear model has lower r2 with a larger SD in predictive results than that of BP-ANN model, which indicated ANN model is more suitable for estimating FFM. PMID:23388042

  6. Impedance analysis of nanostructured iridium oxide electrocatalysts

    International Nuclear Information System (INIS)

    Sunde, Svein; Lervik, Ingrid Anne; Tsypkin, Mikhail; Owe, Lars-Erik

    2010-01-01

    Impedance data were collected for nanostructured iridium oxide (NIROF) at potentials below those at which the oxygen evolution reaction commences. The measurements included thin oxide films covered by a protective Nafion TM layer and thicker composite Nafion TM -oxide electrodes. The time constants for the low-frequency diffusion process were approximately the same for both types of electrodes, indicating diffusion in individual particles in the porous electrode rather than across the film. The diffusion process involves trapping of the diffusion species. The impedance data indicated that there were no significant variations in conductivity of the oxides with potential, as opposed to what appears to be the case for anodically formed iridium oxide films (AIROF). This is interpreted to reflect differences in electronic structure between NIROF and AIROF.

  7. Bioelectrical impedance analysis of bovine milk fat

    Science.gov (United States)

    Veiga, E. A.; Bertemes-Filho, P.

    2012-12-01

    Three samples of 250ml at home temperature of 20°C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.

  8. Bioelectrical impedance analysis of bovine milk fat

    Energy Technology Data Exchange (ETDEWEB)

    Veiga, E A; Bertemes-Filho, P [Department of Electrical Eng., State University of Santa Catarina, Joinville (Brazil)

    2012-12-20

    Three samples of 250ml at home temperature of 20 Degree-Sign C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.

  9. Bioelectrical impedance analysis of bovine milk fat

    International Nuclear Information System (INIS)

    Veiga, E A; Bertemes-Filho, P

    2012-01-01

    Three samples of 250ml at home temperature of 20°C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.

  10. Morphotectonic control of the Białka drainage basin (Central Carpathians: Insights from DEM and morphometric analysis.

    Directory of Open Access Journals (Sweden)

    Wołosiewicz Bartosz

    2016-06-01

    Full Text Available The Białka river valley is directly related to a deep NNW-SSE oriented fault zone. According to the results of previous morphometric analyses, the Białka drainage basin is one of the most tectonically active zones in the Central Carpathians. It is also located within an area of high seismic activity.

  11. Fat mass to fat-free mass ratio reference values from NHANES III using bioelectrical impedance analysis.

    Science.gov (United States)

    Xiao, J; Purcell, S A; Prado, C M; Gonzalez, M C

    2017-10-06

    Low fat-free mass (FFM) or high fat mass (FM) are abnormal body composition phenotypes associated with morbidity. These conditions in combination lead to worse health outcomes, and can be identified by a high FM/FFM ratio. Here, we developed sex, age, and body mass index (BMI) stratified, population-based FM/FFM reference values using bioelectrical impedance analysis (BIA) measurements. White, non-Hispanic individuals aged 18-90 years old with data for weight, stature and BIA resistance measures from the third National Health and Nutrition Examination Survey (NHANES) III were included. Previously validated and sex-specific BIA prediction equations were used to calculate FM and FFM. FM/FFM values were generated at 5th, 50th and 95th percentiles for each sex, age (18-39.9, 40-59.9, 60-69.9 and 70-90 years), and BMI category (underweight, normal weight, overweight, class I/II and class III obesity). A total of 6372 individuals who had estimated FM and FFM values were identified (3366 females, 3006 males). Median values of FM/FFM were 0.24 and 0.40 for young (≤39.9 years) males and females with normal BMI, and 0.34 for males and 0.59 for females who were overweight. For elderly individuals aged >70 years, median FM/FFM for males and females were respectively 0.28 and 0.45 for those with normal BMI, and 0.37 and 0.61 for those in the overweight category. These FM/FFM reference values provide information on body composition characteristics that account for age, sex and BMI, which can be useful to identify individuals at risk for body composition abnormalities. Copyright © 2017 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  12. Effect of the ethinylestradiol/norelgestromin contraceptive patch on body composition. Results of bioelectrical impedance analysis in a population of Italian women

    Directory of Open Access Journals (Sweden)

    Bruni Vincenzina

    2008-08-01

    Full Text Available Abstract Background As weight gain is one of the most frequently cited reasons for not using and for discontinuing hormonal contraceptives, in an open-label, single-arm, multicentre clinical study we evaluated the effect of the ethinylestradiol/norelgestromin contraceptive patch (EVRA, Janssen-Cilag International, Belgium on body composition using bioelectrical impedance analysis (BIA. Methods Body weight and impedance vector components (resistance (R and reactance (Xc, at 50 kHz frequency, Akern-RJL Systems analyzer were recorded before entry, after 1, 3 and 6 months in 182 Italian healthy women aged 29 yr (18 to 45, and with BMI 21.8 kg/m2 (16 to 31. Total body water (TBW was estimated with a BIA regression equation. Vector BIA was performed with the RXc mean graph method and the Hotelling's T2 test for paired and unpaired data. Results After 6 months body weight increased by 0.64 kg (1.1% and TBW increased by 0.51 L (1.7%. The pattern of impedance vector displacement indicated a small increase in soft tissue hydration (interstitial gel fluid. Body composition changes did not significantly differ among groups of previous contraceptive methods. Arterial blood pressure did not significantly change over time. Conclusion After 6 months of treatment with the ethinylestradiol/norelgestromin contraceptive patch we found a minimal, clinically not relevant, increase in body weight less than 1 kg that could be attributed to an adaptive interstitial gel hydration. This fluctuation is physiological as confirmed by the lack of any effect on blood pressure. This could be useful in increasing women's choice, acceptability and compliance of the ethinylestradiol/norelgestromin contraceptive patch.

  13. Is bioelectrical impedance accurate for use in large epidemiological studies?

    Directory of Open Access Journals (Sweden)

    Merchant Anwar T

    2008-09-01

    Full Text Available Abstract Percentage of body fat is strongly associated with the risk of several chronic diseases but its accurate measurement is difficult. Bioelectrical impedance analysis (BIA is a relatively simple, quick and non-invasive technique, to measure body composition. It measures body fat accurately in controlled clinical conditions but its performance in the field is inconsistent. In large epidemiologic studies simpler surrogate techniques such as body mass index (BMI, waist circumference, and waist-hip ratio are frequently used instead of BIA to measure body fatness. We reviewed the rationale, theory, and technique of recently developed systems such as foot (or hand-to-foot BIA measurement, and the elements that could influence its results in large epidemiologic studies. BIA results are influenced by factors such as the environment, ethnicity, phase of menstrual cycle, and underlying medical conditions. We concluded that BIA measurements validated for specific ethnic groups, populations and conditions can accurately measure body fat in those populations, but not others and suggest that for large epdiemiological studies with diverse populations BIA may not be the appropriate choice for body composition measurement unless specific calibration equations are developed for different groups participating in the study.

  14. Validity of bioelectrical impedance measurement in predicting fat-free mass of Chinese children and adolescents.

    Science.gov (United States)

    Wang, Lin; Hui, Stanley Sai-chuen; Wong, Stephen Heung-sang

    2014-11-15

    The current study aimed to examine the validity of various published bioelectrical impedance analysis (BIA) equations in estimating FFM among Chinese children and adolescents and to develop BIA equations for the estimation of fat-free mass (FFM) appropriate for Chinese children and adolescents. A total of 255 healthy Chinese children and adolescents aged 9 to 19 years old (127 males and 128 females) from Tianjin, China, participated in the BIA measurement at 50 kHz between the hand and the foot. The criterion measure of FFM was also employed using dual-energy X-ray absorptiometry (DEXA). FFM estimated from 24 published BIA equations was cross-validated against the criterion measure from DEXA. Multiple linear regression was conducted to examine alternative BIA equation for the studied population. FFM estimated from the 24 published BIA equations yielded high correlations with the directly measured FFM from DEXA. However, none of the 24 equations was statistically equivalent with the DEXA-measured FFM. Using multiple linear regression and cross-validation against DEXA measurement, an alternative prediction equation was determined as follows: FFM (kg)=1.613+0.742×height (cm)2/impedance (Ω)+0.151×body weight (kg); R2=0.95; SEE=2.45 kg; CV=6.5, 93.7% of the residuals of all the participants fell within the 95% limits of agreement. BIA was highly correlated with FFM in Chinese children and adolescents. When the new developed BIA equations are applied, BIA can provide a practical and valid measurement of body composition in Chinese children and adolescents.

  15. Nutrition Status Parameters and Hydration Status by Bioelectrical Impedance Vector Analysis Were Associated With Lung Function Impairment in Children and Adolescents With Cystic Fibrosis.

    Science.gov (United States)

    Hauschild, Daniela Barbieri; Barbosa, Eliana; Moreira, Emilia Addison Machado; Ludwig Neto, Norberto; Platt, Vanessa Borges; Piacentini Filho, Eduardo; Wazlawik, Elisabeth; Moreno, Yara Maria Franco

    2016-06-01

    (1) To compare nutrition and hydration status between a group of children/adolescents with cystic fibrosis (CFG; n = 46; median age, 8.5 years) and a control group without cystic fibrosis (CG). (2) To examine the association of nutrition and hydration status with lung function in the CFG. A cross-sectional study. Nutrition screening, anthropometric parameters, and bioelectrical impedance analysis (BIA) were assessed. The z scores for body mass index for age, height for age, mid upper arm circumference, triceps and subscapular skinfold thickness, mid upper arm muscle area, resistance/height, and reactance/height were calculated. Bioelectrical impedance vector analysis was conducted. Forced expiratory volume in 1 second hydration status were associated with lung function. © 2016 American Society for Parenteral and Enteral Nutrition.

  16. Randomized trial of bioelectrical impedance analysis versus clinical criteria for guiding ultrafiltration in hemodialysis patients: effects on blood pressure, hydration status, and arterial stiffness.

    Science.gov (United States)

    Onofriescu, Mihai; Mardare, Nicoleta Genoveva; Segall, Liviu; Voroneanu, Luminiţa; Cuşai, Claudiu; Hogaş, Simona; Ardeleanu, Serban; Nistor, Ionuţ; Prisadă, Octavian Viorel; Sascău, Radu; Covic, Adrian

    2012-04-01

    Chronic fluid overload is common in maintenance hemodialysis (HD) patients and is associated with severe cardiovascular complications, such as arterial hypertension, left ventricular hypertrophy, congestive heart failure, and arrhythmia. Therefore, a crucial target of HD is to achieve the so-called dry weight; however, the best way to assess fluid status and dry weight is still unclear. Dry weight is currently determined in most dialysis units on a clinical basis, and it is commonly defined as the lowest body weight a patient can tolerate without developing intra-dialytic or inter-dialytic hypotension or other symptoms of dehydration. One of the most promising methods that have emerged in recent years is bioelectrical impedance analysis (BIA), which estimates body composition, including hydration status, by measuring the body's resistance and reactance to electrical current. Our objective was to study the effect BIA-guided versus clinical-guided ultrafiltration on various cardiovascular disease risk factors and markers in HD patients. We included 135 HD patients from a single center in a prospective study, aiming to compare the long-term (12 months) effect of BIA-based versus clinical-based assessment of dry weight on blood pressure (BP), pulse wave velocity (PWV), and serum N-terminal fragment of B-type natriuretic peptide (NT-proBNP). The body composition was measured using the portable whole-body multifrequency BIA device, Body Composition Monitor-BCM(®) (Fresenius Medical Care, Bad Homburg, Germany). In the "clinical" group there were no changes in BP, body mass index (BMI), and body fluids. The PWV increased from 7.9 ± 2.5 to 9.2 ± 3.6 m/s (P = 0.002), whereas serum NT-proBNP decreased from 5,238 to 3,883 pg/ml (P = 0.05). In the "BIA" group, BMI and body volumes also did not change; however, there was a significant decrease in both systolic BP, from 144.6 ± 14.7 to 135.3 ± 17.8 mmHg (P < 0.001), and diastolic BP, from 79.5 ± 9.7 to 73.2 ± 11.1 mmHg (P

  17. The validity and accuracy in foot-to-foot bioelectrical impedance ...

    African Journals Online (AJOL)

    owner

    2011-04-18

    Apr 18, 2011 ... impedance analysis measuring models referenced by dual-energy ... The ZF-F value was 481.85 ± 63.37 ohm in male and ... BIA method to predict the body composition such as ... position have been published, the comparison of various ..... Bioimpedance analysis: evaluation of leg-to-leg system based.

  18. Application of Vertical Electrodes in Microfluidic Channels for Impedance Analysis

    Directory of Open Access Journals (Sweden)

    Qiang Li

    2016-05-01

    Full Text Available This paper presents a microfluidic device with electroplated vertical electrodes in the side walls for impedance measurement. Based on the proposed device, the impedance of NaCl solutions with different concentrations and polystyrene microspheres with different sizes was measured and analyzed. The electroplating and SU-8-PDMS (SU-8-poly(dimethylsiloxane bonding technologies were firstly integrated for the fabrication of the proposed microfluidic device, resulting in a tightly three-dimensional structure for practical application. The magnitude of impedance of the tested solutions in the frequency range of 1 Hz to 100 kHz was analyzed by the Zennium electrochemical workstation. The results show that the newly designed microfluidic device has potential for impedance analysis with the advantages of ease of fabrication and the integration of 3D electrodes in the side walls. The newly designed impedance sensor can distinguish different concentrations of polystyrene microspheres and may have potential for cell counting in biological areas. By integrating with other techniques such as dielectrophoresis (DEP and biological recognition technology, the proposed device may have potential for the assay to identify foodborne pathogen bacteria.

  19. An impact analysis of the fault impedance on voltage sags

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Alessandro Candido Lopes [CELG - Companhia Energetica de Goias, Goiania, GO (Brazil). Generation and Transmission. System' s Operation Center], E-mail: alessandro.clr@celg.com.br; Batista, Adalberto Jose [Federal University of Goias (UFG), Goiania, GO (Brazil)], E-mail: batista@eee.ufg.br; Leborgne, Roberto Chouhy [Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)], E-mail: rcl@ece.ufrgs.br; Emiliano, Pedro Henrique Mota, E-mail: ph@phph.com.br

    2009-07-01

    This paper presents an impact analysis of the fault impedance, in terms of its module and angle, on voltage sags caused by faults. Symmetrical and asymmetrical faults are simulated, at transmission and distribution lines, by using a frequency-domain fault simulation software called ANAFAS. Voltage sags are monitored at buses where sensitive end-users are connected. In order to overcome some intrinsic limitations of this software concerning its automatic execution for several cases, a computational tool was developed in Java programming language. This solution allows the automatic simulation of cases including the effect of the fault position, the fault type, and the proper fault impedance. The main conclusion is that the module and angle of the fault impedance can have a significant influence on voltage sag depending on the fault characteristics. (author)

  20. Validation of bioelectrical impedance analysis in Ethiopian adults with HIV

    DEFF Research Database (Denmark)

    Hegelund, Maria H; Wells, Jonathan C; Girma, Tsinuel

    2017-01-01

    in populations of different ethnic origin and health status. The aim of the present study was to test the validity of BIA in Ethiopian antiretroviral-naive HIV patients. BIA was validated against the 2H dilution technique by comparing fat-free mass (FFM) measured by the two methods using paired t tests and Bland...... % were underweight with a BMI below 18·5 kg/m2. There were no differences in FFM between the methods. Overall, BIA slightly underestimated FFM by 0·1 kg (-0·1, 95 % CI -0·3, 0·2 kg). The Bland-Altman plot indicated acceptable agreement with an upper limit of agreement of 4·5 kg and a lower limit...... of agreement of -4·6 kg, but with a small correlation between the mean difference and the average FFM. BIA slightly overestimated FFM at low values compared with the 2H dilution technique, while it slightly underestimated FFM at high values. In conclusion, BIA proved to be valid in this population and may...

  1. [Comparison BMC assessed by dual-energy X-ray absorptiometry and multi-frequency bioelectrical impedance in Chinese overweight and obesity adults].

    Science.gov (United States)

    Wang, Zhenghe; Fu, Lianguo; Yang, Yide; Wang, Shuo; Ma, Jun

    2016-05-01

    To compare consistency of Body Mineral Content (BMC, kg) assessed by Multi-frequency Bioelectrical Impedance Analysis ( MF-BIA) and Dual Energy X-ray Absorptiometry (DXA) measurement, providing evidence for MF-BIA accurate application in Chinese overweight/obese adults. A total of 1323 overweight/obesity adults aged 22-55 years were recruited voluntarily. All the subjects received the measurement of BMC both using MF-BIA and DXA. To evaluate the agreement of BMC measured by MF-BIA and DXA using interclass correlation coefficients (ICC), then establish correction prediction models. The mean difference of BMC between two methods was significant different with 0, overweight male subgroup was 0.28 kg, and 0.38 kg for obesity male, 0.24 kg for overweight female and 0.36 kg for obesity female, respectively (P BMC between MF-BIA and DXA measurement were statistically significant in all subgroups (P BMC (DXA method) = -0.297 + 1.005 x BMC (MF-BIA method). Obese male population: BMC (DXA method) =0.302 + 0.799 x BMC (MF-BIA method). Overweight female groups: BMC (DXA method) = 0.780 + 0.598 x BMC (MF-BIA method). Obese female group: BMC (DXA method) = 0.755 + 0.597 x BMC (MF-BIA method). Upon examination, correction prediction models were better. Co The correlation and agreement of BMC measured by BIA and DXA are weak in Chinese overweight/obese adults. Therefore, consideration should be given to BMC measured by BIA method in Chinese overweight/obese adults. It should be corrected or adjusted to reduce errors compared with DXA method.

  2. Estimativa da massa muscular esquelética em mulheres idosas: validade da impedância bioelétrica Validity of bioelectrical impedance analysis for the estimation of skeletal muscle mass in elderly women

    Directory of Open Access Journals (Sweden)

    Cassiano Ricardo Rech

    2010-04-01

    Full Text Available O presente estudo tem como objetivos: a verificar a concordância entre os métodos da impedância bioelétrica (BIA e da absortometria radiológica de dupla energia (DXA para a estimativa da massa muscular esquelética (MME; e b analisar o poder preditivo de variáveis antropométricas e da BIA para a predição da MME em idosas. Foram avaliadas 120 mulheres (60 a 81 anos, residentes na região Sul do Brasil. Mensuraram-se as variáveis antropométricas (massa corporal e estatura; a resistência e hidratação dos tecidos livres de gordura foram medidas pela técnica da BIA tetrapolar (Biodinamics - BF-310, e pela DXA de corpo inteiro (Lunar Prodigy DF + 14319 Radiation e software 7.52.002 DPX-L. A diferença entre os métodos foi verificada pelo teste t pareado, análise dos resíduos e o coeficiente de correlação. O valor preditivo das variáveis antropométricas e de BIA foi verificado pela regressão linear múltipla, adotando nível de significância de p 0,01. Observou-se que a BIA subestimou em média 0,8kg (IC95%: -3,7; 2,0kg a MME, quando comparada com a DXA. Foi observada alta correlação entre os métodos (r² = 0,75; p The objectives of the present study were: a to determine the agreement between bioelectrical impedance analysis (BIA and dual-energy X-ray absorptiometry (DXA for the estimation of skeletal muscle mass (SMM, and b to analyze the predictive power of anthropometric variables and BIA for the prediction of SMM in elderly women. A total of 120 women (60 to 81 years, living in the southern region of Brazil, were studied. Anthropometric variables (body weight and height were measured. Resistance and hydration of fat-free tissues were measured by tetrapolar BIA (Biodynamics, BF-310 and by whole-body DXA (Lunar Prodigy DF + 14319 Radiation and DPX-L software, version 7.52.002. Differences between methods were determined using the paired t-test, analysis of residuals and correlation coefficient. The predictive value of the

  3. Phase angle assessment by bioelectrical impedance analysis and its predictive value for malnutrition risk in hospitalized geriatric patients.

    Science.gov (United States)

    Varan, Hacer Dogan; Bolayir, Basak; Kara, Ozgur; Arik, Gunes; Kizilarslanoglu, Muhammet Cemal; Kilic, Mustafa Kemal; Sumer, Fatih; Kuyumcu, Mehmet Emin; Yesil, Yusuf; Yavuz, Burcu Balam; Halil, Meltem; Cankurtaran, Mustafa

    2016-12-01

    Phase angle (PhA) value determined by bioelectrical impedance analysis (BIA) is an indicator of cell membrane damage and body cell mass. Recent studies have shown that low PhA value is associated with increased nutritional risk in various group of patients. However, there have been only a few studies performed globally assessing the relationship between nutritional risk and PhA in hospitalized geriatric patients. The aim of the study is to evaluate the predictive value of the PhA for malnutrition risk in hospitalized geriatric patients. One hundred and twenty-two hospitalized geriatric patients were included in this cross-sectional study. Comprehensive geriatric assessment tests and BIA measurements were performed within the first 48 h after admission. Nutritional risk state of the patients was determined with NRS-2002. Phase angle values of the patients with malnutrition risk were compared with the patients that did not have the same risk. The independent variables for predicting malnutrition risk were determined. SPSS version 15 was utilized for the statistical analyzes. The patients with malnutrition risk had significantly lower phase angle values than the patients without malnutrition risk (p = 0.003). ROC curve analysis suggested that the optimum PhA cut-off point for malnutrition risk was 4.7° with 79.6 % sensitivity, 64.6 % specificity, 73.9 % positive predictive value, and 73.9 % negative predictive value. BMI, prealbumin, PhA, and Mini Mental State Examination Test scores were the independent variables for predicting malnutrition risk. PhA can be a useful, independent indicator for predicting malnutrition risk in hospitalized geriatric patients.

  4. Total and Segmental Body Composition Examination in Collegiate Football Players Using Multifrequency Bioelectrical Impedance Analysis and Dual X-ray Absorptiometry.

    Science.gov (United States)

    Raymond, Christiana J; Dengel, Donald R; Bosch, Tyler A

    2018-03-01

    Raymond, CJ, Dengel, DR, and Bosch, TA. Total and segmental body composition examination in collegiate football players using multifrequency bioelectrical impedance analysis and dual X-ray absorptiometry. J Strength Cond Res 32(3): 772-782, 2018-The current study examined the influence of player position on the agreement between multifrequency bioelectrical impedance analysis (MfBIA) and dual X-ray absorptiometry (DXA) when assessing total and segmental percent body fat (BF%), fat mass (FM), and fat-free mass (FFM) in National Collegiate Athletic Association Division I collegiate football athletes. Forty-four male collegiate athletes (age = 19 ± 1 year; height = 1.9 ± 1.0 m; and body mass = 106.4 ± 18.8 kg) participated. Player positions included: offensive linemen (OL; n = 7), tight ends (TE; n = 4), wide receivers (WR; n = 9), defensive linemen (DL; n = 6), defensive backs (DB; n = 8), linebackers (LB; n = 6), and running backs (RB; n = 4). Total and segmental body composition measured using MfBIA were compared with values obtained using DXA. Compared with DXA, MfBIA underestimated BF% (3.0 ± 3.8%), total FM (2.5 ± 4.3 kg), arm FM (0.4 ± 0.8 kg), arm FFM (1.4 ± 0.9 kg), leg FM (2.8 ± 2.0 kg), and leg FFM (5.4 ± 2.4 kg) (all p FFM (-2.4 ± 4.5 kg) (p FFM), ±3.83 kg (leg FM), ±4.62 kg (leg FFM), and ±8.83 kg (total FFM). No significant differences were observed between devices for trunk FM (-0.3 ± 3.0 kg; p = 0.565) and trunk FFM (0.4 ± 2.4 kg; p = 0.278), with LOAs of ±5.92 and ±4.69 kg, respectively. Player position significantly affected all between-device mean body composition measurement differences (adjusted p ≤ 0.05), with OL demonstrating the greatest effect on each variable. Therefore, MfBIA does not seem accurate in examining between-player body composition in college football players.

  5. Impedance Analysis of Silicon Nanowire Lithium Ion Battery Anodes

    KAUST Repository

    Ruffo, Riccardo

    2009-07-02

    The impedance behavior of silicon nanowire electrodes has been investigated to understand the electrochemical process kinetics that influences the performance when used as a high-capacity anode in a lithium ion battery. The ac response was measured by using impedance spectroscopy in equilibrium conditions at different lithium compositions and during several cycles of charge and discharge in a half cell vs. metallic lithium. The impedance analysis shows the contribution of both surface resistance and solid state diffusion through the bulk of the nanowires. The surface process is dominated by a solid electrolyte layer (SEI) consisting of an inner, inorganic insoluble part and several organic compounds at the outer interface, as seen by XPS analysis. The surface resistivity, which seems to be correlated with the Coulombic efficiency of the electrode, grows at very high lithium contents due to an increase in the inorganic SEI thickness. We estimate the diffusion coefficient of about 2 × 10 -10 cm 2/s for lithium diffusion in silicon. A large increase in the electrode impedance was observed at very low lithium compositions, probably due to a different mechanism for lithium diffusion inside the wires. Restricting the discharge voltage to 0.7 V prevents this large impedance and improves the electrode lifetime. Cells cycled between 0.07 and 0.70 V vs. metallic lithium at a current density of 0.84 A/g (C/5) showed good Coulombic efficiency (about 99%) and maintained a capacity of about 2000 mAh/g after 80 cycles. © 2009 American Chemical Society.

  6. Influence of acute consumption of caffeine vs. placebo over Bia-derived measurements of body composition: a randomized, double-blind, crossover design.

    Science.gov (United States)

    Williamson, Cassie M; Nickerson, Brett S; Bechke, Emily E; McLester, Cherilyn N; Kliszczewicz, Brian M

    2018-01-01

    Bioelectrical impedance analysis (BIA) is often used to estimate total body water (TBW), intracellular body water (ICW), extracellular body water (ECW), and body fat percentage (BF%). A common restriction for BIA analysis is abstinence from caffeine 12-h prior to testing. However, research has yet to determine whether the consumption of caffeine influences BIA testing results. The purpose of this study was to determine if the consumption of caffeine influences BIA-derived BF% and body water values in habitual caffeine users. Twenty apparently healthy males (26.6 ± 4.1 years) identified as habitual caffeine consumers (≥ one 95 mg serving per day ≥ four days per week) participated in this study. Participants came to the lab on three occasions, the first visit serving as the control (CON) with no supplementation. The remaining two visits were performed in a randomized double-blind, cross-over fashion. Participants consumed 200 mg of dextrose (PLA) or caffeine (CAF) in capsule form. During each visit, seven multi-frequency BIA measurements were conducted before (PRE) and after (15-min, 30-min, 45-min, 60-min, 75-min, 90-min) consumption. Repeated measures ANOVA revealed BF% for CAF was lower than the CON and PLA conditions at PRE and 15-min ( p  Caffeine consumption in habitual users produced trivial changes in TBW, ECW, ICW, or BF%. Therefore, the pre-testing guidelines for caffeine consumption may not be necessary in habitual caffeine consumers.

  7. ON THE ANALYSIS OF IMPEDANCE-DRIVEN REVERSE FLOW DYNAMICS

    Directory of Open Access Journals (Sweden)

    LEE V. C.-C.

    2017-02-01

    Full Text Available Impedance pump is a simple valve-less pumping mechanism, where an elastic tube is joined to a more rigid tube, at both ends. By inducing a periodic asymmetrical compression on the elastic tube will produce a unidirectional flow within the system. This pumping concept offers a low energy, low noise alternative, which makes it an effective driving mechanism, especially for micro-fluidic systems. In addition, the wave-based mechanism through which pumping occurs infers many benefits in terms of simplicity of design and manufacturing. Adjustment of simple parameters such as the excitation frequencies or compression locations will reverse the direction of flow, providing a very versatile range of flow outputs. This paper describes the experimental analysis of such impedance-driven flow with emphasis on the dynamical study of the reverse flow in open-loop environment. In this study, tapered section with converging steps is introduced at both ends of the elastic tube to amplify the magnitude of reverse flow. Study conducted shows that the reverse peak flow is rather significant with estimate of 23% lower than the forward peak flow. The flow dynamics on the other hand has shown to exhibit different characteristics as per the forward peak flow. The flow characteristics is then studied and showed that the tapered sections altered the impedance within the system and hence induce a higher flow in the reverse direction.

  8. Utilization of BIA-Derived Bone Mineral Estimates Exerts Minimal Impact on Body Fat Estimates via Multicompartment Models in Physically Active Adults.

    Science.gov (United States)

    Nickerson, Brett S; Tinsley, Grant M

    2018-03-21

    The purpose of this study was to compare body fat estimates and fat-free mass (FFM) characteristics produced by multicompartment models when utilizing either dual energy X-ray absorptiometry (DXA) or single-frequency bioelectrical impedance analysis (SF-BIA) for bone mineral content (BMC) in a sample of physically active adults. Body fat percentage (BF%) was estimated with 5-compartment (5C), 4-compartment (4C), 3-compartment (3C), and 2-compartment (2C) models, and DXA. The 5C-Wang with DXA for BMC (i.e., 5C-Wang DXA ) was the criterion. 5C-Wang using SF-BIA for BMC (i.e., 5C-Wang BIA ), 4C-Wang DXA (DXA for BMC), 4C-Wang BIA (BIA for BMC), and 3C-Siri all produced values similar to 5C-Wang DXA (r > 0.99; total error [TE] FFM characteristics (i.e., FFM density, water/FFM, mineral/FFM, and protein/FFM) for 5C-Wang DXA and 5C-Wang BIA were each compared with the "reference body" cadavers of Brozek et al. 5C-Wang BIA FFM density differed significantly from the "reference body" in women (1.103 ± 0.007 g/cm 3 ; p FFM and mineral/FFM were significantly lower in men and women when comparing 5C-Wang DXA and 5C-Wang BIA with the "reference body," whereas protein/FFM was significantly higher (all p ≤ 0.001). 3C-Lohman BIA and 3C-Lohman DXA produced error similar to 2C models and DXA and are therefore not recommended multicompartment models. Although more advanced multicompartment models (e.g., 4C-Wang and 5C-Wang) can utilize BIA-derived BMC with minimal impact on body fat estimates, the increased accuracy of these models over 3C-Siri is minimal. Copyright © 2018 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.

  9. Can abdominal bioelectrical impedance refine the determination of visceral fat from waist circumference?

    International Nuclear Information System (INIS)

    Watson, S; Blundell, H L; Evans, W D; Griffiths, H; Newcombe, R G; Rees, D A

    2009-01-01

    Ryo et al (2005 Diabetes Care 28 451–3) reported a new method for measuring the visceral fat area (VFA) by combining abdominal bioelectrical impedance analysis (BIA) with measurement of waist circumference (WC), but very few methodological details were provided. Furthermore, the study did not test the use of WC alone as an indicator of VFA even though others had previously reported a strong correlation. We sought to determine the optimal measurement technique and analysis for measuring VFA by abdominal BIA and WC. 18 volunteers (age 23–64 years) underwent measurement of WC, abdominal impedance (Bodystat 500 four-electrode system) and a single cross-sectional CT scan at the umbilicus. VFA derived using WC 3 and measurements of abdominal impedance from electrode pairs sited at the flank predicted the value of VFA measured by CT with correlation r = 0.904 (p 1.9 alone, without involving BIA at all, provided a similar correlation (r = 0.923). Our small preliminary study shows that abdominal BIA is potentially a practicable non-invasive technique for measurement of VFA but casts doubt on whether it adds any value to the use of WC alone. Larger studies are now required to test this finding. (note)

  10. Cross-mode bioelectrical impedance analysis in a standing position for estimating fat-free mass validated against dual-energy x-ray absorptiometry.

    Science.gov (United States)

    Huang, Ai-Chun; Chen, Yu-Yawn; Chuang, Chih-Lin; Chiang, Li-Ming; Lu, Hsueh-Kuan; Lin, Hung-Chi; Chen, Kuen-Tsann; Hsiao, An-Chi; Hsieh, Kuen-Chang

    2015-11-01

    Bioelectrical impedance analysis (BIA) is commonly used to assess body composition. Cross-mode (left hand to right foot, Z(CR)) BIA presumably uses the longest current path in the human body, which may generate better results when estimating fat-free mass (FFM). We compared the cross-mode with the hand-to-foot mode (right hand to right foot, Z(HF)) using dual-energy x-ray absorptiometry (DXA) as the reference. We hypothesized that when comparing anthropometric parameters using stepwise regression analysis, the impedance value from the cross-mode analysis would have better prediction accuracy than that from the hand-to-foot mode analysis. We studied 264 men and 232 women (mean ages, 32.19 ± 14.95 and 34.51 ± 14.96 years, respectively; mean body mass indexes, 24.54 ± 3.74 and 23.44 ± 4.61 kg/m2, respectively). The DXA-measured FFMs in men and women were 58.85 ± 8.15 and 40.48 ± 5.64 kg, respectively. Multiple stepwise linear regression analyses were performed to construct sex-specific FFM equations. The correlations of FFM measured by DXA vs. FFM from hand-to-foot mode and estimated FFM by cross-mode were 0.85 and 0.86 in women, with standard errors of estimate of 2.96 and 2.92 kg, respectively. In men, they were 0.91 and 0.91, with standard errors of the estimates of 3.34 and 3.48 kg, respectively. Bland-Altman plots showed limits of agreement of -6.78 to 6.78 kg for FFM from hand-to-foot mode and -7.06 to 7.06 kg for estimated FFM by cross-mode for men, and -5.91 to 5.91 and -5.84 to 5.84 kg, respectively, for women. Paired t tests showed no significant differences between the 2 modes (P > .05). Hence, cross-mode BIA appears to represent a reasonable and practical application for assessing FFM in Chinese populations. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Analysis of activity in swine producers group based on agricultural producers association in Biała district

    Directory of Open Access Journals (Sweden)

    Damian Knecht

    2013-03-01

    Full Text Available The process of pigs producer groups formation in Poland is quite dynamic. Currently on the pork market 181 groups operate, which includes about 4000 swine producers. The aim of this study was to characterize the activities of the Agricultural Producers Association in Biała District. The research tool was a personal questionnaire and the research sample consisted of 30 farmers. It has been shown that after joining the producers group, the investigated households reported an increase in sales volume and improved the flock production parameters. Majority of the respondents were not satisfied with the cooperation with meat processing companies.

  12. Impedance analysis of the PEP-II vacuum chamber

    International Nuclear Information System (INIS)

    Ng, C.K.; Weiland, T.

    1995-05-01

    The PEP-II high energy ring (HER) vacuum chamber consists of a copper tube with periodically spaced pumping slots. The impedance of the vacuum chamber due to the slots is analyzed. Both narrow-band and broadband impedances are considered as well as longitudinal and transverse components thereof. It is found that although the broad-band impedance is tolerable, the narrow-band impedance may exceed the instability limit given by the natural damping with no feedback system on. Traveling wave modes in the chamber are the major source of this high value narrow-band impedance. We also study the dependences of the impedance on the slot length and the geometrical cross section

  13. New reference values for body composition by bioelectrical impedance analysis in the general population: results from the UK Biobank.

    Science.gov (United States)

    Franssen, Frits M E; Rutten, Erica P A; Groenen, Miriam T J; Vanfleteren, Lowie E; Wouters, Emiel F M; Spruit, Martijn A

    2014-06-01

    Low fat-free mass (FFM) is a risk factor for morbidity and mortality in elderly and patient populations. Therefore, measurement of FFM is important in nutritional assessment. Bioelectrical impedance analysis (BIA) is a convenient method to assess FFM and FFM index (FFMI; FFM/height(2)). Although reference values have been established for individuals with normal body weight, no specific cutoff values are available for overweight and obese populations. Also, limited studies accounted for the age-related decline in FFM. To determine BMI- and age-specific reference values for abnormal low FFM(I) in white-ethnic men and women free of self-reported disease from the general population. The UK Biobank is a prospective epidemiological study of the general population from the United Kingdom. Individuals in the age category 45 to 69 years were analyzed. In addition to body weight, FFM and FFMI were measured using a Tanita BC-418MA. Also, self-reported chronic conditions and ethnic background were registered, and lung function was assessed using spirometry. After exclusion of all individuals with missing data, nonwhite ethnicity, self-reported disease, body mass index (BMI) less than 14 or 36 kg/m(2) or higher, and/or an obstructive lung function, reference values for FFM and FFMI were derived from 186,975 individuals (45.9% men; age: 56.9 ± 6.8 years; BMI: 26.5 ± 3.6 kg/m(2); FFMI 18.3 ± 2.4 kg/m(2)). FFM and FFMI were significantly associated with BMI and decreased with age. Percentiles 5, 10, 25, 50, 75, 90, and 95 were calculated for FFM, FFMI, and fat mass (index), after stratification for gender, age, and BMI. Using the UK Biobank dataset, new reference values for body composition assessed with BIA were determined in white-ethnic men and women aged 45 to 69 years. Because these reference values are BMI specific, they are of broad interest for overweight and obese populations. Copyright © 2014 American Medical Directors Association, Inc. Published by Elsevier Inc. All

  14. Impedance Analysis of Silicon Nanowire Lithium Ion Battery Anodes

    KAUST Repository

    Ruffo, Riccardo; Hong, Seung Sae; Chan, Candace K.; Huggins, Robert A.; Cui, Yi

    2009-01-01

    The impedance behavior of silicon nanowire electrodes has been investigated to understand the electrochemical process kinetics that influences the performance when used as a high-capacity anode in a lithium ion battery. The ac response was measured

  15. Impedance Synthesis Based Vibration Analysis of Geared Transmission System

    Directory of Open Access Journals (Sweden)

    Yafeng Ren

    2017-01-01

    Full Text Available The severity of gear noise response depends on the sensitivity of geared rotor system dynamics to the transmission error. As gearbox design trending towards lighter weight and lower noise, the influence of housing compliance on system dynamic characteristics cannot be ignored. In this study, a gear-shaft-bearing-housing coupled impedance model is proposed to account for the effect of housing compliance on the vibration of geared transmission system. This proposed dynamic model offers convenient modeling, efficient computing, and ability to combine computed parameters with experimental ones. The numerical simulations on system dynamic characteristics are performed for both a rigid housing configuration and a flexible one. Natural frequencies, dynamic mesh forces, and dynamic bearing reaction loads are computed, and the housing compliance contribution on system dynamic characteristics is analyzed. Results show that increasing housing compliance will decrease the system natural frequencies and will affect the dynamic bearing reaction loads significantly but have very little influence on the dynamic mesh force. Also, the analysis shows that bearing stiffness has significant influence on the degree of housing contribution on system dynamic characteristics.

  16. Prediction of fat-free body mass from bioelectrical impedance among 9- to 11-year-old Swedish children

    DEFF Research Database (Denmark)

    Nielsen, Birgit Marie; Dencker, M; Ward, L

    2007-01-01

    AIM: Predictive equations for estimating body composition from bioelectrical impedance analysis (BIA) among Scandinavian children are lacking. In the present study, equations for estimation of fat-free body mass (FFM) and lean tissue mass (LTM) were developed and cross-validated from BIA using dual...... linear regression and cross-validated against DXA measurements of body composition. RESULTS: FFM was predicted from BIA and anthropometric variables with an adjusted R(2)= 0.95 and root mean square error (RMSE) = 0.84 kg, and LTM was predicted with an adjusted R(2)= 0.95 and RMSE = 0.87 kg. Cross......-validation revealed a mean RMSE = 0.95 kg FFM and a mean RMSE = 0.96 kg LTM. Prediction of body composition from equations developed in previous literature was mixed when applied to the present cohort of children. CONCLUSIONS: FFM and LTM are predicted with sufficient accuracy at the population level. We recommend...

  17. Two port network analysis for three impedance based oscillators

    KAUST Repository

    Said, Lobna A.

    2011-12-01

    Two-port network representations are applied to analyze complex networks which can be dissolved into sub-networks connected in series, parallel or cascade. In this paper, the concept of two-port network has been studied for oscillators. Three impedance oscillator based on two port concept has been analyzed using different impedance structures. The effect of each structure on the oscillation condition and the frequency of oscillation have been introduced. Two different implementations using MOS and BJT have been introduced. © 2011 IEEE.

  18. Impedance-Based High Frequency Resonance Analysis of DFIG System in Weak Grids

    DEFF Research Database (Denmark)

    Song, Yipeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    Resonance (SSR). However, the High Frequency Resonance (HFR) of DFIG systems due to the impedance interaction between DFIG system and parallel compensated weak network is often overlooked. This paper thus investigates the impedance characteristics of DFIG systems for the analysis of HFR. The influences...

  19. Ethnic variability in body size, proportions and composition in children aged 5 to 11 years: is ethnic-specific calibration of bioelectrical impedance required?

    Directory of Open Access Journals (Sweden)

    Simon Lee

    Full Text Available Bioelectrical Impedance Analysis (BIA has the potential to be used widely as a method of assessing body fatness and composition, both in clinical and community settings. BIA provides bioelectrical properties, such as whole-body impedance which ideally needs to be calibrated against a gold-standard method in order to provide accurate estimates of fat-free mass. UK studies in older children and adolescents have shown that, when used in multi-ethnic populations, calibration equations need to include ethnic-specific terms, but whether this holds true for younger children remains to be elucidated. The aims of this study were to examine ethnic differences in body size, proportions and composition in children aged 5 to 11 years, and to establish the extent to which such differences could influence BIA calibration.In a multi-ethnic population of 2171 London primary school-children (47% boys; 34% White, 29% Black African/Caribbean, 25% South Asian, 12% Other detailed anthropometric measurements were performed and ethnic differences in body size and proportion were assessed. Ethnic differences in fat-free mass, derived by deuterium dilution, were further evaluated in a subsample of the population (n = 698. Multiple linear regression models were used to calibrate BIA against deuterium dilution.In children < 11 years of age, Black African/Caribbean children were significantly taller, heavier and had larger body size than children of other ethnicities. They also had larger waist and limb girths and relatively longer legs. Despite these differences, ethnic-specific terms did not contribute significantly to the BIA calibration equation (Fat-free mass = 1.12+0.71*(height2/impedance+0.18*weight.Although clear ethnic differences in body size, proportions and composition were evident in this population of young children aged 5 to 11 years, an ethnic-specific BIA calibration equation was not required.

  20. BMI or BIA: Is Body Mass Index or Body Fat Mass a Better Predictor of Cardiovascular Risk in Overweight or Obese Children and Adolescents?

    Directory of Open Access Journals (Sweden)

    Barbara Bohn

    2015-04-01

    Full Text Available Background: Body fat (BF percentiles for German children and adolescents have recently been published. This study aims to evaluate the association between bioelectrical impedance analysis(BIA-derived BF and cardiovascular risk factors and to investigate whether BF is better suited than BMI in children and adolescents. Methods: Data of 3,327 children and adolescents (BMI > 90th percentile were included. Spearman's correlation and receiver operating characteristics (ROCs were applied determining the associations between BMI or BF and cardiovascular risk factors (hypertension, dyslipidemia, elevated liver enzymes, abnormal carbohydrate metabolism. Area under the curve (AUC was calculated to predict cardiovascular risk factors. Results: A significant association between both obesity indices and hypertension was present (all p Conclusion: BIA-derived BF was not superior to BMI to predict cardiovascular risk factors in overweight or obese children and adolescents.

  1. A dielectrophoresis-impedance method for protein detection and analysis

    Science.gov (United States)

    Mohamad, Ahmad Sabry; Hamzah, Roszymah; Hoettges, Kai F.; Hughes, Michael Pycraft

    2017-01-01

    Dielectrophoresis (DEP) has increasingly been used for the assessment of the electrical properties of molecular scale objects including proteins, DNA, nanotubes and nanowires. However, whilst techniques have been developed for the electrical characterisation of frequency-dependent DEP response, biomolecular study is usually limited to observation using fluorescent markers, limiting its applicability as a characterisation tool. In this paper we present a label-free, impedance-based method of characterisation applied to the determination of the electrical properties of colloidal protein molecules, specifically Bovine Serum Albumin (BSA). By monitoring the impedance between electrodes as proteins collect, it is shown to be possible to observe multi-dispersion behaviour. A DEP dispersion exhibited at 400 kHz is attributable to the orientational dispersion of the molecule, whilst a second, higher-frequency dispersion is attributed to a Maxwell-Wagner type dispersion; changes in behaviour with medium conductivity suggest that this is strongly influenced by the electrical double layer surrounding the molecule.

  2. Assessment of body composition by segmental bioelectrical impedance method in Japanese college athletes : focus on the different characteristic of sports

    OpenAIRE

    村松, 愛梨奈; 乙木, 幸道; 井川, 正治

    2013-01-01

    The purpose of this study was to clarify a characteristic of body composition of limbs in Japanese athletes by the segmental bioelectric impedance analysis (S-BIA) method. The subjects were 131 college athletes (baseball, volleyball, handball, combined competition, wrestling, soft tennis, swimming; athletes group) and 107 healthy college students (control group). The items of measurement were body height, body weight, BMI, percent of body fat (%FAT), skeletal muscle mass (SMM). We measured %F...

  3. The French National Authority for Health (HAS) Guidelines for Conducting Budget Impact Analyses (BIA).

    Science.gov (United States)

    Ghabri, Salah; Autin, Erwan; Poullié, Anne-Isabelle; Josselin, Jean Michel

    2018-04-01

    Budget impact analysis (BIA) provides short- and medium-term estimates on changes in budgets and health outcomes resulting from the adoption of new health interventions. The purpose of this study is to present the newly developed French National Authority for Health (HAS) guidelines on budget impact analysis as follows: process, literature review, recommendations and comparisons with other guidelines. The development process of the HAS guidelines included a literature review (search dates: January 2000 to June 2016), a retrospective investigation of BIA previously submitted to HAS, a public consultation, international expert reviews and approval from the HAS Board and the Economic and Public Health Evaluation Committee of HAS. Documents identified in the literature review included 12 national guidelines, 5 recommendations for good practices developed by national and international society of health economics and 14 methodological publications including recommendations for conducting BIA. Based on its research findings, HAS developed its first BIA guidelines, which include recommendations on the following topics: BIA definition, perspective, populations, time horizon, compared scenarios, budget impact models, costing, discounting, choice of clinical data, reporting of results and uncertainty exploration. It is expected that the HAS BIA guidelines will enhance the usefulness, quality and transparency of BIA submitted by drug manufacturers to HAS. BIA is becoming an essential part of a comprehensive economic assessment of healthcare interventions in France, which also includes cost-effectiveness analysis and equity of access to healthcare.

  4. A dielectrophoresis-impedance method for protein detection and analysis

    Directory of Open Access Journals (Sweden)

    Ahmad Sabry Mohamad

    2017-01-01

    Full Text Available Dielectrophoresis (DEP has increasingly been used for the assessment of the electrical properties of molecular scale objects including proteins, DNA, nanotubes and nanowires. However, whilst techniques have been developed for the electrical characterisation of frequency-dependent DEP response, biomolecular study is usually limited to observation using fluorescent markers, limiting its applicability as a characterisation tool. In this paper we present a label-free, impedance-based method of characterisation applied to the determination of the electrical properties of colloidal protein molecules, specifically Bovine Serum Albumin (BSA. By monitoring the impedance between electrodes as proteins collect, it is shown to be possible to observe multi-dispersion behaviour. A DEP dispersion exhibited at 400 kHz is attributable to the orientational dispersion of the molecule, whilst a second, higher-frequency dispersion is attributed to a Maxwell-Wagner type dispersion; changes in behaviour with medium conductivity suggest that this is strongly influenced by the electrical double layer surrounding the molecule.

  5. Analysis of Human Fibroadenomas Using Three-Dimensional Impedance Maps

    Science.gov (United States)

    Dapore, Alexander J.; King, Michael R.; Harter, Josephine; Sarwate, Sandhya; Oelze, Michael L.; Zagzebski, James A.; Do, Minh N.; Hall, Timothy J.

    2012-01-01

    Three-dimensional impedance maps (3DZMs) are virtual volumes of acoustic impedance values constructed from histology to represent tissue microstructure acoustically. From the 3DZM, the ultrasonic backscattered power spectrum can be predicted and model based scatterer properties, such as effective scatterer diameter (ESD), can be estimated. Additionally, the 3DZM can be exploited to visualize and identify possible scattering sites, which may aid in the development of more effective scattering models to better represent the ultrasonic interaction with underlying tissue microstructure. In this study, 3DZMs were created from a set of human fibroadenoma samples. ESD estimates were made assuming a fluid-filled sphere form factor model from 3DZMs of volume 300 × 300 × 300 µm. For a collection of 33 independent human fibroadenoma tissue samples, the ESD was estimated to be 111 ± 40.7 µm. The 3DZMs were then investigated visually to identify possible scattering sources which conformed to the estimated model scatterer dimensions. This estimation technique allowed a better understanding of the spatial distribution and variability of the estimates throughout the volume. PMID:21278015

  6. Analytical Model for High Impedance Fault Analysis in Transmission Lines

    Directory of Open Access Journals (Sweden)

    S. Maximov

    2014-01-01

    Full Text Available A high impedance fault (HIF normally occurs when an overhead power line physically breaks and falls to the ground. Such faults are difficult to detect because they often draw small currents which cannot be detected by conventional overcurrent protection. Furthermore, an electric arc accompanies HIFs, resulting in fire hazard, damage to electrical devices, and risk with human life. This paper presents an analytical model to analyze the interaction between the electric arc associated to HIFs and a transmission line. A joint analytical solution to the wave equation for a transmission line and a nonlinear equation for the arc model is presented. The analytical model is validated by means of comparisons between measured and calculated results. Several cases of study are presented which support the foundation and accuracy of the proposed model.

  7. An integrated microfluidic analysis microsystems with bacterial capture enrichment and in-situ impedance detection

    Science.gov (United States)

    Liu, Hai-Tao; Wen, Zhi-Yu; Xu, Yi; Shang, Zheng-Guo; Peng, Jin-Lan; Tian, Peng

    2017-09-01

    In this paper, an integrated microfluidic analysis microsystems with bacterial capture enrichment and in-situ impedance detection was purposed based on microfluidic chips dielectrophoresis technique and electrochemical impedance detection principle. The microsystems include microfluidic chip, main control module, and drive and control module, and signal detection and processing modulet and result display unit. The main control module produce the work sequence of impedance detection system parts and achieve data communication functions, the drive and control circuit generate AC signal which amplitude and frequency adjustable, and it was applied on the foodborne pathogens impedance analysis microsystems to realize the capture enrichment and impedance detection. The signal detection and processing circuit translate the current signal into impendence of bacteria, and transfer to computer, the last detection result is displayed on the computer. The experiment sample was prepared by adding Escherichia coli standard sample into chicken sample solution, and the samples were tested on the dielectrophoresis chip capture enrichment and in-situ impedance detection microsystems with micro-array electrode microfluidic chips. The experiments show that the Escherichia coli detection limit of microsystems is 5 × 104 CFU/mL and the detection time is within 6 min in the optimization of voltage detection 10 V and detection frequency 500 KHz operating conditions. The integrated microfluidic analysis microsystems laid the solid foundation for rapid real-time in-situ detection of bacteria.

  8. Change in fat-free mass assessed by bioelectrical impedance, total body potassium and dual energy X-ray absorptiometry during prolonged weight loss

    DEFF Research Database (Denmark)

    Hendel, H W; Gotfredsen, A; Højgaard, L

    1996-01-01

    ). These measurements were compared with bioimpedance analysis (BIA) by applying 11 predictive BIA equations published in the literature. Predictive equations for the present study population were developed, with the use of fat-free mass (FFM) as assessed by TBK and DXA as references in multiple regression analysis....... The results of the BIA equations varied widely; FFM was generally overestimated by BIA as compared with DXA and TBK before and after weight loss. During weight loss, the FFM did not change, as estimated by DXA (1.3 +/- 2.3 kg, p > 0.05) and TBK (0.9 +/- 2.9 kg, p > 0.05). The recorded change in impedance (R......) was also insignificant. Three BIA equations from the literature, which were not specific for the degree of obesity in the present study group, predicted changes in FFM (from 0.5 + 3.6 to 2.4 +/- 4.4kg, p > 0.05) that were comparable with those estimated by the reference methods. Eight equations from...

  9. Study of the dopamine effect into cell solutions by impedance analysis

    Science.gov (United States)

    Paivana, G.; Apostolou, T.; Kaltsas, G.; Kintzios, S.

    2017-11-01

    Electrochemical Impedance Spectroscopy (EIS) has become a technique that is frequently used for biological assays. Impedance is defined as a complex - valued generalization of resistance and varies depending on its use per application field. In health sciences, bioimpedance is widely used as non-invasive and low cost alternative in many medical areas that provides valuable information about health status. This work focuses on assessing the effects of a bioactive substance applied to immobilized cells. Dopamine was used as a stimulant in order to implement impedance analysis with a specific type of cells. Dopamine constitutes one of the most important catecholamine neurotransmitters in both the mammalian central and peripheral nervous systems. The main purpose is to extract calibration curves at different frequencies with known dopamine concentrations in order to describe the behavior of cells applied to dopamine using an impedance measurement device. For comparison purposes, non-immobilized cells were tested for the same dopamine concentrations.

  10. Estimation of body fat from anthropometry and bioelectrical impedance in Native American children.

    Science.gov (United States)

    Lohman, T G; Caballero, B; Himes, J H; Davis, C E; Stewart, D; Houtkooper, L; Going, S B; Hunsberger, S; Weber, J L; Reid, R; Stephenson, L

    2000-08-01

    Obesity, as measured by body mass index, is highly prevalent in Native American children, yet there are no valid equations to estimate total body fatness for this population. This study was designed to develop equations to estimate percentage body fat from anthropometry and bioelectrical impedance as a critical part of Pathways, a multi-site study of primary prevention of obesity in Native American children. Percentage fat was estimated from deuterium oxide dilution in 98 Native American children (Pima/Maricopa, Tohono O'odham and White Mountain Apache tribes) between 8 and 11 y of age. The mean fat content (38.4%+/-8. 1%) was calculated assuming the water content of the fat-free body was 76%. Initial independent variables were height, weight, waist circumference, six skinfolds and whole-body resistance and reactance from bioelectrical impedance (BIA). Using all-possible-subsets regressions with the Mallows C (p) criterion, and with age and sex included in each regression model, waist circumference, calf and biceps skinfolds contributed least to the multiple regression analysis. The combination of weight, two skinfolds (any two out of the four best: triceps, suprailiac, subscapular and abdomen) and bioelectrical impedance variables provided excellent predictability. Equations without BIA variables yielded r2 almost as high as those with BIA variables. The recommended equation predicts percentage fat with a root mean square error=3.2% fat and an adjusted r2=0.840. The combination of anthropometry and BIA variables can be used to estimate total body fat in field studies of Native American children. The derived equation yields considerably higher percentage fat values than other skinfold equations in children.

  11. Application of impedance spectroscopy method for analysis of benzanol fuels

    Directory of Open Access Journals (Sweden)

    Mamykin A. V.

    2015-06-01

    Full Text Available The authors have developed a method for express control of three component «gasoline-alcohol-water» fuel mixtures based on the spectral impedance investigation of benzanol mixture in the frequency range of 500 Hz — 10 kHz. A correlation dependence between the dielectric constant and the specific resistance of the fuel mixture on content of ethanol and water in the mixture has been found. On the basis of this dependence a calibration nomogram to quantify the gasoline and water-alcohol components content in the test benzanol fuel in the actual range of concentrations has been formed. The nomogram allows determining the water-alcohol and gasoline parts in the analyzed fuel with an error of no more than 1% vol., while the strength of water-alcohol solution is determined with an error of no more than 0.8% vol. The obtained nomogram can also give information about critical water content in the benzanol fuel to prevent its eventual phase separation. It is shown that the initial component composition of different gasoline brands has no significant effect on the electrical characteristics of the studied benzanol fuels, which makes the evaluation of alcohol and water content in the fuel sufficiently accurate. for practical applications.

  12. Coupling of impedance functions to nuclear reactor building for soil-structure interaction analysis

    International Nuclear Information System (INIS)

    Danisch, R.; Delinic, K.; Trbojevic, V.M.

    1991-01-01

    Finite element model of a nuclear reactor building is coupled to complex soil impedance functions and soil-structure-interaction analysis is carried out in frequency domain. In the second type of analysis applied in this paper, soil impedance functions are used to evaluate equivalent soil springs and dashpots of soil. These are coupled to the structure model in order to carry out the time marching analysis. Three types of soil profiles are considered: hard, medium and soft. Results of two analyzes are compared on the same structural model. Equivalent soil springs and dashpots are determined using new method based on the least square approximation. (author)

  13. Hybrid Microfluidic Platform for Multifactorial Analysis Based on Electrical Impedance, Refractometry, Optical Absorption and Fluorescence

    Directory of Open Access Journals (Sweden)

    Fábio M. Pereira

    2016-10-01

    Full Text Available This paper describes the development of a novel microfluidic platform for multifactorial analysis integrating four label-free detection methods: electrical impedance, refractometry, optical absorption and fluorescence. We present the rationale for the design and the details of the microfabrication of this multifactorial hybrid microfluidic chip. The structure of the platform consists of a three-dimensionally patterned polydimethylsiloxane top part attached to a bottom SU-8 epoxy-based negative photoresist part, where microelectrodes and optical fibers are incorporated to enable impedance and optical analysis. As a proof of concept, the chip functions have been tested and explored, enabling a diversity of applications: (i impedance-based identification of the size of micro beads, as well as counting and distinguishing of erythrocytes by their volume or membrane properties; (ii simultaneous determination of the refractive index and optical absorption properties of solutions; and (iii fluorescence-based bead counting.

  14. An experimental applications of impedance measurements by spectral analysis to electrochemistry and corrosion

    International Nuclear Information System (INIS)

    Castro, E.B.; Vilche, J.R.; Milocco, R.H.

    1984-01-01

    An impedance measurement system based on the spectral analysis of excitation and response signals was implemented using a pseudo-random binary sequence in the generation of the electrical perturbation signal. The spectral density functions were estimated through finite Fourier transforms of the original time history records by fast computation of Fourier series. Experimental results obtained using the FFT algorithm in the developed impedance measurement system which covers a wide frequency range, 10 KHz >= f >= 1 mHz, are given both for dummy cells representing conventional electric circuits in electrochemistry and corrosion systems and for the Fe/acidic chloride solution interfaces under different polarization conditions. (C.L.B.) [pt

  15. Impedance characteristics of DFIGs considering the impacts of DFIG numbers and its application on SSR analysis

    Science.gov (United States)

    You, J. J.; Ning, W. Y.; Jiang, H.; Dong, Y. X.; Liu, H.; Li, Y.

    2017-05-01

    Sub-synchronous resonance (SSR) occurred in the power system with both Doubly Fed Induction Generators (DFIGs) and series-compensated lines. There have been several papers focusing on the analysis of such SSR phenomenon. To the authors’ knowledge, the impacts of DFIG numbers are seldom considered in existing papers. In this paper, the impedance characteristics of DFIGs under different numbers are analyzed. Then the relationship between DFIG numbers and SSR characteristics is discussed. The contributions to be included in the paper are as following: 1) the impedance of N DFIGs is roughly equal to 1/N of the impedance of one DFIG. 2) The SSR risk of system is related with both the numbers of DFIGs and the parameters of the series-compensated lines.

  16. Modelling of passive films: complementarity and applicability to the electrochemical impedance spectroscopy analysis

    International Nuclear Information System (INIS)

    Boissy, Clement; Normand, Bernard

    2013-01-01

    A review of the published models to describe the passivation of metallic materials is proposed. The objective is to illustrate the importance of the selection of a model considering their complementarity. The discussion is based on an analysis to assess whether the mass transport in the film must be taken into account or not in the modelling of the electrochemical impedance. (authors)

  17. A model-based prognostic approach to predict interconnect failure using impedance analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Dae Il; Yoon, Jeong Ah [Dept. of System Design and Control Engineering. Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2016-10-15

    The reliability of electronic assemblies is largely affected by the health of interconnects, such as solder joints, which provide mechanical, electrical and thermal connections between circuit components. During field lifecycle conditions, interconnects are often subjected to a DC open circuit, one of the most common interconnect failure modes, due to cracking. An interconnect damaged by cracking is sometimes extremely hard to detect when it is a part of a daisy-chain structure, neighboring with other healthy interconnects that have not yet cracked. This cracked interconnect may seem to provide a good electrical contact due to the compressive load applied by the neighboring healthy interconnects, but it can cause the occasional loss of electrical continuity under operational and environmental loading conditions in field applications. Thus, cracked interconnects can lead to the intermittent failure of electronic assemblies and eventually to permanent failure of the product or the system. This paper introduces a model-based prognostic approach to quantitatively detect and predict interconnect failure using impedance analysis and particle filtering. Impedance analysis was previously reported as a sensitive means of detecting incipient changes at the surface of interconnects, such as cracking, based on the continuous monitoring of RF impedance. To predict the time to failure, particle filtering was used as a prognostic approach using the Paris model to address the fatigue crack growth. To validate this approach, mechanical fatigue tests were conducted with continuous monitoring of RF impedance while degrading the solder joints under test due to fatigue cracking. The test results showed the RF impedance consistently increased as the solder joints were degraded due to the growth of cracks, and particle filtering predicted the time to failure of the interconnects similarly to their actual timesto- failure based on the early sensitivity of RF impedance.

  18. Avo analysis in the high impedance reservoir of Chuchupa Field

    International Nuclear Information System (INIS)

    Cediel Mauricio; Almanza Ovidio; Montes Luis

    2012-01-01

    The technique of bright spot as a direct indicator of hydrocarbons has been widely used since the work of Ostrander (1984), particularly in gas fields. Located at north of Colombia, the Chuchupa field has produced gas continuously during 30 years, but despite the coverage with 2D seismic, amplitude anomalies associated with gas accumulation have not been observed. In order to find the relationships between the amplitude information and the gas accumulation, an AVO analysis was performed to describe the seismic reservoir response. The raw data of a 2D seismic line that crosses the field from East to West and a well log data set were used. In a first approach the seismic response was modeled using well logs, so a comparative analysis between the furnished synthetic seismograms and the real CDP gathers was done. The results indicated that the reservoirs top is represented by a low amplitude peak which decreases when the offset increases but whose phase remains unchanged. In the well, where the reservoir has 100% gas saturation, a high correlation between the synthetic and real CDP gathers was observed. In a second approach, anomalous clustered points in the IV quadrant were discriminated through intercept versus gradient cross plot analysis. A weak Class-I anomaly was identified, which could not be observed in stacked sections and hence it should be analyzed using pre-stack data.

  19. Analysis of smart beams with piezoelectric elements using impedance matrix and inverse Laplace transform

    International Nuclear Information System (INIS)

    Li, Guo-Qing; Miao, Xing-Yuan; Hu, Yuan-Tai; Wang, Ji

    2013-01-01

    A comprehensive study on smart beams with piezoelectric elements using an impedance matrix and the inverse Laplace transform is presented. Based on the authors’ previous work, the dynamics of some elements in beam-like smart structures are represented by impedance matrix equations, including a piezoelectric stack, a piezoelectric bimorph, an elastic straight beam or a circular curved beam. A further transform is applied to the impedance matrix to obtain a set of implicit transfer function matrices. Apart from the analytical solutions to the matrices of smart beams, one computation procedure is proposed to obtained the impedance matrices and transfer function matrices using FEA. By these means the dynamic solution of the elements in the frequency domain is transformed to that in Laplacian s-domain and then inversely transformed to time domain. The connections between the elements and boundary conditions of the smart structures are investigated in detail, and one integrated system equation is finally obtained using the symbolic operation of TF matrices. A procedure is proposed for dynamic analysis and control analysis of the smart beam system using mode superposition and a numerical inverse Laplace transform. The first example is given to demonstrate building transfer function associated impedance matrices using both FEA and analytical solutions. The second example is to verify the ability of control analysis using a suspended beam with PZT patches under close-loop control. The third example is designed for dynamic analysis of beams with a piezoelectric stack and a piezoelectric bimorph under various excitations. The last example of one smart beam with a PPF controller shows the applicability to the control analysis of complex systems using the proposed method. All results show good agreement with the other results in the previous literature. The advantages of the proposed methods are also discussed at the end of this paper. (paper)

  20. Differences in body composition measured using the bioelectrical impedance analysis with steel and gel electrodes – on an example of professional fencers

    Directory of Open Access Journals (Sweden)

    Olga Mizera

    2018-03-01

    Full Text Available Introduction: Regular assessment of body composition in athletes is a key element of their nutritional status and general condition monitoring. Purpose: Analysis of differences in the impedance (I and body composition measurements performed by the use of analyzers with a constant current frequency of 50 kHz with steel and gel electrodes. Material and methods: Analysis were performed in experienced fencers by the use of analyzers: Tanita BC418MA (aT with steel electrodes (eT and Akern BIA101ASE (aA with gel electrodes (eA, eL, eT. During the first stage of the study in 48 athletes I, fat mass (FM and fat free mass (FFM were measured using aA with eB in a supine position and after 3 min using aT with eT in a standing position. Then 10 fencers were randomly selected. For them measurements were performed after 10, 13 and 16 min in a supine position using eA, eL, eB and then after 3 min in a standing one using eT. Intrinsic impedance of the 3 types of gel electrodes (eA, eL, eB were measured using aA. Results: The first stage. Differences in I, FM and FFM between eT and aA were observed (women: 101.4±52.2Ω, 1.2±2.1kg, -1.2±2.1kg, men: 98.8±27.5Ω, 1.1±1.5kg, -1.1±1.5kg, respectively. The second stage. In the subsequent measurements, differences in I were observed (women: eL-eA 3.8±1.8Ω, eB-eA 26.1±8.0Ω, eT-eA 154.4±40.6Ω;, men: of -0.7±9.4Ω, 11.1±9.2Ω, 107±36.3Ω, respectively. In both subgroups along with the increase in I, FM also increased, while  FFM decreased. Intrinsic impedance of the applied gel electrodes was measured and the differences between the results were reported (eL-eA 41.1±22.0Ω, eB-eL 138.4±20.7Ω, eB-eA 179.5Ω. As the intrinsic impedance of gel electrodes increased, an increase in the whole body I was observed. Conclusion: It seems that the observed differences in the whole body impedance were not only a simple effect of changes in a body position but they might have also been related to the intrinsic

  1. Analysis of Conductor Impedances Accounting for Skin Effect and Nonlinear Permeability

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, M P; Ong, M M; Brown, C G; Speer, R D

    2011-07-20

    It is often necessary to protect sensitive electrical equipment from pulsed electric and magnetic fields. To accomplish this electromagnetic shielding structures similar to Faraday Cages are often implemented. If the equipment is inside a facility that has been reinforced with rebar, the rebar can be used as part of a lighting protection system. Unfortunately, such shields are not perfect and allow electromagnetic fields to be created inside due to discontinuities in the structure, penetrations, and finite conductivity of the shield. In order to perform an analysis of such a structure it is important to first determine the effect of the finite impedance of the conductors used in the shield. In this paper we will discuss the impedances of different cylindrical conductors in the time domain. For a time varying pulse the currents created in the conductor will have different spectral components, which will affect the current density due to skin effects. Many construction materials use iron and different types of steels that have a nonlinear permeability. The nonlinear material can have an effect on the impedance of the conductor depending on the B-H curve. Although closed form solutions exist for the impedances of cylindrical conductors made of linear materials, computational techniques are needed for nonlinear materials. Simulations of such impedances are often technically challenging due to the need for a computational mesh to be able to resolve the skin depths for the different spectral components in the pulse. The results of such simulations in the time domain will be shown and used to determine the impedances of cylindrical conductors for lightning current pulses that have low frequency content.

  2. Improvement of nutritional status as assessed by multifrequency BIA during 15 weeks of refeeding in adolescent girls with anorexia nervosa.

    Science.gov (United States)

    Mika, Claudia; Herpertz-Dahlmann, Beate; Heer, Martina; Holtkamp, Kristian

    2004-11-01

    In patients with anorexia nervosa (AN), an assessment of changes in body composition and nutritional status is crucial for adequate nutritional management during refeeding therapies. Phase-sensitive multifrequency bioelectrical impedance analysis (BIA) is an inexpensive and noninvasive technique with which to determine nutritional status and body composition. We investigated 21 female adolescents with AN (initial BMI 15.5 +/- 1.1 kg/m(2)) 4 times between wk 3 and 15 of inpatient refeeding and 19 normal-weight, age-matched female controls. From wk 3 to 15, BMI, fat mass, body cell mass (BCM), total body water (TBW), intracellular water (ICW) but not extracellular mass (ECM), and extracellular water (ECW) increased significantly. Reactance (Xc), phase angle (PhA), and the ECM/BCM index as parameters of nutritional status improved significantly in patients and no longer differed from controls in wk 15, although the BMI of patients was significantly lower than those of controls. Changes in the ECM/BCM index were due to accretion of BCM, which was associated with an increase of ICW. Multifrequency phase-sensitive BIA seems to be a promising tool for the assessment of changes in nutritional status and body composition in patients with AN. An individually determined and controlled hyperenergetic diet as part of a multidimensional, interdisciplinary treatment program for eating disorders seems to quickly improve the nutritional status of AN patients.

  3. Determination of bone mineral volume fraction using impedance analysis and Bruggeman model

    Energy Technology Data Exchange (ETDEWEB)

    Ciuchi, Ioana Veronica; Olariu, Cristina Stefania, E-mail: oocristina@yahoo.com; Mitoseriu, Liliana, E-mail: lmtsr@uaic.ro

    2013-11-20

    Highlights: • Mineral volume fraction of a bone sample was determined. • Dielectric properties for bone sample and for the collagen type I were determined by impedance spectroscopy. • Bruggeman effective medium approximation was applied in order to evaluate mineral volume fraction of the sample. • The computed values were compared with ones derived from a histogram test performed on SEM micrographs. -- Abstract: Measurements by impedance spectroscopy and Bruggeman effective medium approximation model were employed in order to determine the mineral volume fraction of dry bone. This approach assumes that two or more phases are present into the composite: the matrix (environment) and the other ones are inclusion phases. A fragment of femur diaphysis dense bone from a young pig was investigated in its dehydrated state. Measuring the dielectric properties of bone and its main components (hydroxyapatite and collagen) and using the Bruggeman approach, the mineral volume filling factor was determined. The computed volume fraction of the mineral volume fraction was confirmed by a histogram test analysis based on the SEM microstructures. In spite of its simplicity, the method provides a good approximation for the bone mineral volume fraction. The method which uses impedance spectroscopy and EMA modeling can be further developed by considering the conductive components of the bone tissue as a non-invasive in situ impedance technique for bone composition evaluation and monitoring.

  4. Bioelectrical impedance analysis to define an excess of body fat: evaluation in patients with psoriasis.

    Science.gov (United States)

    Galluzzo, M; Talamonti, M; Perino, F; Servoli, S; Giordano, D; Chimenti, S; De Simone, C; Peris, K

    2017-06-01

    There is strong evidence that obesity is closely associated with psoriasis. However, data on body composition are lacking in psoriasis. The purpose of this study were to investigate the body composition in psoriasis patients using bioelectrical impedance analysis and to correlate the bioelectrical impedance data with disease severity and laboratory parameters. Anthropometric measurements and bioelectrical impedance analyses were performed on patients with psoriasis, naïve to any systemic treatment, who attended the outpatient clinics of two University centers. Data of 164 adult patients were analyzed. Compared to men, women had several significantly higher bioelectrical impedance parameters including reactance, fat mass% and adipose tissue%. The values of adipose tissue were positively correlated only with patients age (p = .021) and age at disease onset (p = .0006), but not with disease severity. In addition, we observed that the use of BMI cutoffs allowed to categorize 36.7% of women and 19.2% of men as obese, while fat mass% showed that 53.3% of women and 48.1% of men were obese. In our study, psoriasis is been associated with a high fat mass%. We suggest that screening for body fat distribution in psoriatic patients might be useful to identify early obesity-related disease.

  5. Determination of bone mineral volume fraction using impedance analysis and Bruggeman model

    International Nuclear Information System (INIS)

    Ciuchi, Ioana Veronica; Olariu, Cristina Stefania; Mitoseriu, Liliana

    2013-01-01

    Highlights: • Mineral volume fraction of a bone sample was determined. • Dielectric properties for bone sample and for the collagen type I were determined by impedance spectroscopy. • Bruggeman effective medium approximation was applied in order to evaluate mineral volume fraction of the sample. • The computed values were compared with ones derived from a histogram test performed on SEM micrographs. -- Abstract: Measurements by impedance spectroscopy and Bruggeman effective medium approximation model were employed in order to determine the mineral volume fraction of dry bone. This approach assumes that two or more phases are present into the composite: the matrix (environment) and the other ones are inclusion phases. A fragment of femur diaphysis dense bone from a young pig was investigated in its dehydrated state. Measuring the dielectric properties of bone and its main components (hydroxyapatite and collagen) and using the Bruggeman approach, the mineral volume filling factor was determined. The computed volume fraction of the mineral volume fraction was confirmed by a histogram test analysis based on the SEM microstructures. In spite of its simplicity, the method provides a good approximation for the bone mineral volume fraction. The method which uses impedance spectroscopy and EMA modeling can be further developed by considering the conductive components of the bone tissue as a non-invasive in situ impedance technique for bone composition evaluation and monitoring

  6. Hardware Design of Tuber Electrical Resistance Tomography System Based on the Soil Impedance Test and Analysis

    OpenAIRE

    Liu Shuyi; Deng Xiang; Jiang Zili; Tang Yu

    2016-01-01

    The hardware design of tuber electrical resistance tomography (TERT) system is one of the key research problems of TERT data acquisition system. The TERT system can be applied to the tuber growth process monitoring in agriculture, i.e., the TERT data acquisition system can realize the real imaging of tuber plants in soil. In TERT system, the imaging tuber and soil multiphase medium is quite complexity. So, the impedance test and analysis of soil multiphase medium is very important to the desi...

  7. Detection of thoracic vascular structures by electrical impedance tomography: a systematic assessment of prominence peak analysis of impedance changes.

    Science.gov (United States)

    Wodack, K H; Buehler, S; Nishimoto, S A; Graessler, M F; Behem, C R; Waldmann, A D; Mueller, B; Böhm, S H; Kaniusas, E; Thürk, F; Maerz, A; Trepte, C J C; Reuter, D A

    2018-02-28

    Electrical impedance tomography (EIT) is a non-invasive and radiation-free bedside monitoring technology, primarily used to monitor lung function. First experimental data shows that the descending aorta can be detected at different thoracic heights and might allow the assessment of central hemodynamics, i.e. stroke volume and pulse transit time. First, the feasibility of localizing small non-conductive objects within a saline phantom model was evaluated. Second, this result was utilized for the detection of the aorta by EIT in ten anesthetized pigs with comparison to thoracic computer tomography (CT). Two EIT belts were placed at different thoracic positions and a bolus of hypertonic saline (10 ml, 20%) was administered into the ascending aorta while EIT data were recorded. EIT images were reconstructed using the GREIT model, based on the individual's thoracic contours. The resulting EIT images were analyzed pixel by pixel to identify the aortic pixel, in which the bolus caused the highest transient impedance peak in time. In the phantom, small objects could be located at each position with a maximal deviation of 0.71 cm. In vivo, no significant differences between the aorta position measured by EIT and the anatomical aorta location were obtained for both measurement planes if the search was restricted to the dorsal thoracic region of interest (ROIs). It is possible to detect the descending aorta at different thoracic levels by EIT using an intra-aortic bolus of hypertonic saline. No significant differences in the position of the descending aorta on EIT images compared to CT images were obtained for both EIT belts.

  8. Change in fat-free mass assessed by bioelectrical impedance, total body potassium and dual energy X-ray absorptiometry during prolonged weight loss

    DEFF Research Database (Denmark)

    Hendel, H W; Gotfredsen, A; Højgaard, L

    1996-01-01

    A total of 16 obese women (body mass index (BMI) 30-43 kg m(-2)) participated in a weight reduction study. Before and after a weight loss of 11.7 +/- 7.4 kg (mean +/- SD), body composition was assessed by dual energy X-ray absorptiometry (DXA), and total body potassium counting (TBK). These measu......A total of 16 obese women (body mass index (BMI) 30-43 kg m(-2)) participated in a weight reduction study. Before and after a weight loss of 11.7 +/- 7.4 kg (mean +/- SD), body composition was assessed by dual energy X-ray absorptiometry (DXA), and total body potassium counting (TBK......). These measurements were compared with bioimpedance analysis (BIA) by applying 11 predictive BIA equations published in the literature. Predictive equations for the present study population were developed, with the use of fat-free mass (FFM) as assessed by TBK and DXA as references in multiple regression analysis....... The results of the BIA equations varied widely; FFM was generally overestimated by BIA as compared with DXA and TBK before and after weight loss. During weight loss, the FFM did not change, as estimated by DXA (1.3 +/- 2.3 kg, p > 0.05) and TBK (0.9 +/- 2.9 kg, p > 0.05). The recorded change in impedance (R...

  9. Electrochemical Impedance Spectroscopic Analysis of RuO2 Based Thick Film pH Sensors

    International Nuclear Information System (INIS)

    Manjakkal, Libu; Djurdjic, Elvira; Cvejin, Katarina; Kulawik, Jan; Zaraska, Krzysztof; Szwagierczak, Dorota

    2015-01-01

    The conductimetric interdigitated thick film pH sensors based on RuO 2 were fabricated and their electrochemical reactions with solutions of different pH values were studied by electrochemical impedance spectroscopy (EIS) technique. The microstructural properties and composition of the sensitive films were examined by scanning electron microscopy, X-ray energy dispersive spectroscopy and Raman spectroscopy. The EIS analysis of the sensor was carried out in the frequency range 10 mHz–2 MHz for pH values of test solutions 2–12. The electrical parameters of the sensor were found to vary with changing pH. The conductance and capacitance of the film were distinctly dependent on pH in the low frequency range. The Nyquist and Bode plots derived from the impedance data for the metal oxide thick film pH sensor provided information about the underlying electrochemical reactions

  10. Electrochemical Characterization and Degradation Analysis of Large SOFC Stacks by Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Mosbæk, Rasmus Rode; Hjelm, Johan; Barfod, R.

    2013-01-01

    As solid oxide fuel cell (SOFC) technology is moving closer to a commercial break through, lifetime limiting factors, and methods to measure the “state-of-health” of operating cells and stacks are becoming of increasing interest. This requires application of advanced methods for detailed...... electrochemical characterization during operation. An experimental stack with low ohmic resistance from Topsoe Fuel Cell A/S was characterized in detail using electrochemical impedance spectroscopy (EIS). An investigation of the optimal geometrical placement of the current feeds and voltage probes was carried out...... with hydrogen as fuel with 52% fuel utilization and constant current load (0.2 A cm–2) at 750 °C. Stack interconnects were coated with six different coatings to prevent chromium poisoning on the cathode side. Four repeating units (RUs) with different coatings were selected for detailed impedance analysis. EIS...

  11. Multivariate analysis of electrical impedance spectra for relaxed and contracted skeletal muscle

    International Nuclear Information System (INIS)

    Zagar, T; Krizaj, D

    2008-01-01

    Four-electrode impedance spectra of relaxed and contracted muscle biceps brachii were analyzed in an adult human subject over the frequency range from 300 Hz to 75 kHz. A feasibility of the principal component analysis of bioimpedance measurement for the evaluation of skeletal muscle contractile state was examined. The principal components score plots show a data grouping of the impedance spectra from the two muscle groups. The classification was performed using a soft independent modeling of class analogy (SIMCA) method. The data set comprised 32 samples (16 samples of contracted muscle and 16 samples of relaxed muscle). The leave-one-out test of the classification yields about 80% of correctly classified samples (11 samples for contracted and 15 samples for relaxed muscle)

  12. Role of radiation damping in the impedance function approach to soil-structure interaction analysis

    International Nuclear Information System (INIS)

    1980-05-01

    This report was prepared at the request of the Lawrence Livermore Laboratory (LLL) to provide background information for analyzing soil-structure interaction by the frequency-independent impedance function approach. LLL is conducting such analyses as part of its seismic review of selected operating plants under the Systematic Evaluation Program for the US Nuclear Regulatory Commission. The analytical background and basic assumptionsof the impedance function theory are briefly reviewed, and the role of radiation damping in soil-structure interaction analysis is discussed. The validity of modeling soil-structure interaction by using frequency-independent functions is evaluated based on data from several field tests. Finally, the recommended procedures for performing soil-structure interaction analyses are discussed with emphasis on the modal superposition method

  13. Hardware Design of Tuber Electrical Resistance Tomography System Based on the Soil Impedance Test and Analysis

    Directory of Open Access Journals (Sweden)

    Liu Shuyi

    2016-01-01

    Full Text Available The hardware design of tuber electrical resistance tomography (TERT system is one of the key research problems of TERT data acquisition system. The TERT system can be applied to the tuber growth process monitoring in agriculture, i.e., the TERT data acquisition system can realize the real imaging of tuber plants in soil. In TERT system, the imaging tuber and soil multiphase medium is quite complexity. So, the impedance test and analysis of soil multiphase medium is very important to the design of sensitive array sensor subsystem and signals processing circuits. In the paper, the soil impedance test experimental is described and the results are analysed. The data acquisition hardware system is designed based on the result of soil medium impedance test and analysis. In the hardware design, the switch control chip ADG508, the instrumentation amplifier AD620 and programmable amplifier AD526 are employed. In the meantime, the phase locked loop technique for signal demodulation is introduced. The initial data collection is given and discussed under the conditions of existing plant tuber and no existing plant tuber. Conclusions of the hardware design of TERT system are presented.

  14. Bioelectrical impedance analysis for the prediction of hot carcass weight in buffalo calf

    Directory of Open Access Journals (Sweden)

    Leopoldo Iannuzzi

    2010-01-01

    Full Text Available Twenty young buffalo male calves were fed ad libitum with a total mix ration and with vitamin-mineral integration for 14 months. Seven days before slaughter, the animals were weighed and bioelectrical impedance measurements were collected in live animals. Physical and chemical characteristics were assessed on the Longissimus dorsi muscle after slaughter. Correlations and regression equations were calculated to determine the possible use of bioelectrical impedance for evaluating hot carcass weight. Bioelectrical impedance analysis at different frequencies, simple correlation and analysis of regression were examined for all the data collected, supporting the possibility of hot carcass weight prediction with equation at multifrequency. The results show that, probably due to the variability in animal live weight, the distribution of the colour parameters was not normally distributed. Moreover, using different frequencies of resistance and reactance, hot carcass weight in buffalo may be predicted with the following equation: Y=98.47–8.84(Rs100KHz+4.41(Rs1000 KHz-116.27(Xc5 KHz+51.04(Xc50 KHz+20.30(Xc100 KHz-33.92(Xc500 KHz+9.01(Xc1000 KHz±ε (Adjusted R Square value of .907 and SE of 5.728 However, further studies are required to improve the technique also in buffalo, after standardization of the method.

  15. Uncertainty and sensitivity analysis of electro-mechanical impedance based SHM system

    International Nuclear Information System (INIS)

    Rosiek, M; Martowicz, A; Uhl, T

    2010-01-01

    The paper deals with the application of uncertainty and sensitivity analysis performed for FE simulations for electro-mechanical impedance based SHM system. The measurement of electro-mechanical impedance allows to follow changes of mechanical properties of monitored construction. Therefore it can be effectively applied to conclude about presence of damage. Coupled FE simulations have been carried out for simultaneous consideration of both structural dynamics and piezoelectric properties of a simple beam with bonded transducer. Several indexes have been used to assess the damage growth. In the paper the results obtained with both deterministic and stochastic simulations are shown and discussed. First, the relationship between size of introduced damage and its indexes has been studied. Second, ranges of variation of selected model properties have been assumed to find relationships between them and damage indexes. The most influential parameters have been found. Finally, the overall propagation of considered uncertainty has been assessed and related histograms plotted to discuss effectiveness and robustness of tested damage indexes based on the measurement of electro-mechanical impedance.

  16. Fast and sensitive detection of foodborne pathogen using electrochemical impedance analysis, urease catalysis and microfluidics.

    Science.gov (United States)

    Chen, Qi; Wang, Dan; Cai, Gaozhe; Xiong, Yonghua; Li, Yuntao; Wang, Maohua; Huo, Huiling; Lin, Jianhan

    2016-12-15

    Early screening of pathogenic bacteria is a key to prevent and control of foodborne diseases. In this study, we developed a fast and sensitive bacteria detection method integrating electrochemical impedance analysis, urease catalysis with microfluidics and using Listeria as model. The Listeria cells, the anti-Listeria monoclonal antibodies modified magnetic nanoparticles (MNPs), and the anti-Listeria polyclonal antibodies and urease modified gold nanoparticles (AuNPs) were incubated in a fluidic separation chip with active mixing to form the MNP-Listeria-AuNP-urease sandwich complexes. The complexes were captured in the separation chip by applying a high gradient magnetic field, and the urea was injected to resuspend the complexes and hydrolyzed under the catalysis of the urease on the complexes into ammonium ions and carbonate ions, which were transported into a microfluidic detection chip with an interdigitated microelectrode for impedance measurement to determine the amount of the Listeria cells. The capture efficiency of the Listeria cells in the separation chip was ∼93% with a shorter time of 30min due to the faster immuno-reaction using the active magnetic mixing. The changes on both impedance magnitude and phase angle were demonstrated to be able to detect the Listeria cells as low as 1.6×10(2)CFU/mL. The detection time was reduced from original ∼2h to current ∼1h. The recoveries of the spiked lettuce samples ranged from 82.1% to 89.6%, indicating the applicability of this proposed biosensor. This microfluidic impedance biosensor has shown the potential for online, automatic and sensitive bacteria separation and detection. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Structural damage identification using piezoelectric impedance measurement with sparse inverse analysis

    Science.gov (United States)

    Cao, Pei; Qi, Shuai; Tang, J.

    2018-03-01

    The impedance/admittance measurements of a piezoelectric transducer bonded to or embedded in a host structure can be used as damage indicator. When a credible model of the healthy structure, such as the finite element model, is available, using the impedance/admittance change information as input, it is possible to identify both the location and severity of damage. The inverse analysis, however, may be under-determined as the number of unknowns in high-frequency analysis is usually large while available input information is limited. The fundamental challenge thus is how to find a small set of solutions that cover the true damage scenario. In this research we cast the damage identification problem into a multi-objective optimization framework to tackle this challenge. With damage locations and severities as unknown variables, one of the objective functions is the difference between impedance-based model prediction in the parametric space and the actual measurements. Considering that damage occurrence generally affects only a small number of elements, we choose the sparsity of the unknown variables as another objective function, deliberately, the l 0 norm. Subsequently, a multi-objective Dividing RECTangles (DIRECT) algorithm is developed to facilitate the inverse analysis where the sparsity is further emphasized by sigmoid transformation. As a deterministic technique, this approach yields results that are repeatable and conclusive. In addition, only one algorithmic parameter, the number of function evaluations, is needed. Numerical and experimental case studies demonstrate that the proposed framework is capable of obtaining high-quality damage identification solutions with limited measurement information.

  18. Increased abdominal fat levels measured by bioelectrical impedance are associated with histological lesions of nonalcoholic steatohepatitis.

    Science.gov (United States)

    Margariti, Aikaterini; Kontogianni, Meropi D; Tileli, Nafsika; Georgoulis, Michael; Deutsch, Melanie; Zafeiropoulou, Rodessa; Tiniakos, Dina; Manios, Yannis; Pectasides, Dimitrios; Papatheodoridis, George V

    2015-08-01

    Abdominal fat is considered to play an important role in nonalcoholic fatty liver disease (NAFLD), although it is not adequately studied because abdominal fat levels cannot be estimated easily. In this study, associations between abdominal obesity, as assessed by abdominal bioelectrical impedance analysis (BIA), and the characteristics of patients with NAFLD were explored. Seventy-four consecutive NAFLD patients who underwent measurement of abdominal fat levels by BIA were included. Levels of abdominal fat 12.5 or less and more than 12.5 were considered to be average and increased, respectively. The mean±SD BMI was 30±4 kg/m and the mean abdominal fat levels were 16±5, whereas 26% of patients had average abdominal fat levels. Patients with average compared with those with increased abdominal fat levels were more frequently women (50 vs. 12%, P=0.001), had lower BMI (27±3 vs. 31±4 kg/m, Pabdominal fat levels (78 vs. 38%, P=0.030) and in patients with BMI 30 or more compared with less than 30 kg/m (87 vs. 48%, P=0.033), but similar in patients with increased or normal waist circumference (67 vs. 56%, P=0.693). Average levels of abdominal fat, as assessed by abdominal BIA, are mainly present in female patients with NAFLD and are associated with a lower degree of insulin resistance. Increased abdominal fat as assessed by BIA and obesity seem to represent strong risk factors for histological steatohepatitis.

  19. A LabVIEW-based electrical bioimpedance spectroscopic data interpreter (LEBISDI) for biological tissue impedance analysis and equivalent circuit modelling

    KAUST Repository

    Bera, Tushar Kanti

    2016-12-05

    impedance analysis for electrical impedance-based tissue characterization, health analysis and disease diagnosis.

  20. A LabVIEW-based electrical bioimpedance spectroscopic data interpreter (LEBISDI) for biological tissue impedance analysis and equivalent circuit modelling

    KAUST Repository

    Bera, Tushar Kanti; Jampana, Nagaraju; Lubineau, Gilles

    2016-01-01

    impedance analysis for electrical impedance-based tissue characterization, health analysis and disease diagnosis.

  1. Effect of Intravenous Infusion Solutions on Bioelectrical Impedance Spectroscopy.

    Science.gov (United States)

    Yap, Jason; Rafii, Mahroukh; Azcue, Maria; Pencharz, Paul

    2017-05-01

    Bioelectrical impedance (BIA) is often used to measure body fluid spaces and thereby body composition. However, in acute animal studies, we found that impedance was driven by the saline content of intravenous (IV) fluids and not by the volume. The aim of the study was to investigate the effect of 3 different fluids acutely administered on the change in impedance, specifically resistance (R). Nine healthy adults participated in 3 treatment (0.9% saline, 5% dextrose, and a mixture of 0.3% saline + 3.3% dextrose) experiments on nonconsecutive days. They all received 1 L of one of the treatments intravenously over a 1-hour period. Repeated BIA measurements were performed prior to IV infusion and then every 5 minutes for the 1-hour infusion period, plus 3 more measurements up to 15 minutes after the completion of the infusion. The change in R in the 0.9% saline infusion experiment was significantly lower than that of the glucose and mixture treatment ( P < .001). Bioelectrical impedance spectroscopy and BIA measure salt rather than the volume changes over the infusion period. Hence, in patients receiving IV fluids, BIA of any kind (single frequency or multifrequency) cannot be used to measure body fluid spaces or body composition.

  2. Single- and multi-frequency bioelectrical impedance analyses to analyse body composition in maintenance haemodialysis patients: comparison with dual-energy x-ray absorptiometry

    International Nuclear Information System (INIS)

    Donadio, C; Halim, A Ben; Caprio, F; Grassi, G; Khedr, B; Mazzantini, M

    2008-01-01

    The aim of this study was to evaluate the adequacy of single-frequency (sf-BIA) and multi-frequency bioelectrical impedance analyses (mf-BIA), in comparison with dual-energy x-ray absorptiometry (DXA), to evaluate body composition in maintenance haemodialysis (MHD) patients. Body composition of 27 adult MHD patients (9 f, 18 m), BMI 17.5–34.4 kg m −2 , was examined with DXA and BIA, with two different sf-BIA and 1 mf-BIA analysers. Biochemical markers of nutritional status and adequacy of dialytic treatment were also determined. Fat mass (FM) estimated by the different BIA analysers was found to be slightly but significantly higher than FM measured by DXA. In contrast, fat-free mass (FFM) obtained with BIA was found to be slightly but significantly lower than FFM DXA. No significant differences were found between LBM-DXA (that is FFM-DXA minus bone mass) and the different FFM BIA. The lowest mean prediction error versus DXA values was found with sf1BIA. In any case, a close correlation was found between all BIA values and DXA values, particularly for FFM. Furthermore, FFM and LBM results were significantly correlated with serum creatinine, which in MHD patients is an indicator of muscle mass. These results indicate that BIA can be used to evaluate body composition in MHD patients

  3. Evaluation of segmental body composition by gender in obese children using bioelectric impedance analysis method

    Directory of Open Access Journals (Sweden)

    İhsan Çetin

    2015-12-01

    Full Text Available Objective: In this study, it was aimed to evaluate segmental body composition of children diagnosed with obesity using bioelectrical impedance analysis method in terms of different gender. Methods: 48 children, aged between 6-15 years, 21 of whom were boys while 27 were girls, diagnosed with obesity in Erciyes University Medical Faculty Department of Pediatric Endocrinology Outpatient Clinic were included in our study from April to June in 2011. Those over 95 percentile were defined as obese group. Tanita BC-418 device was used to analyze the body composition. Results: As a result of bioelectrical impedance analysis, lean body mass and body muscle mass were found to be statistically significantly higher in obese girls compared with obese boys. However, lean mass of the left arm, left leg muscle mass and basal metabolic rate were found to be statistically significantly lower in obese girls compared with obese boys. Conclusion: Consequently, it may be suggest that segmental analysis, where gender differences are taken into account, can provide proper exercise pattern and healthy way of weight loss in children for prevention of obesity and associated diseases including obesity and type 2 diabetics and cardiovascular diseases.

  4. Bias Voltage-Dependent Impedance Spectroscopy Analysis of Hydrothermally Synthesized ZnS Nanoparticles

    Science.gov (United States)

    Dey, Arka; Dhar, Joydeep; Sil, Sayantan; Jana, Rajkumar; Ray, Partha Pratim

    2018-04-01

    In this report, bias voltage-dependent dielectric and electron transport properties of ZnS nanoparticles were discussed. ZnS nanoparticles were synthesized by introducing a modified hydrothermal process. The powder XRD pattern indicates the phase purity, and field emission scanning electron microscope image demonstrates the morphology of the synthesized sample. The optical band gap energy (E g = 4.2 eV) from UV measurement explores semiconductor behavior of the synthesized material. The electrical properties were performed at room temperature using complex impedance spectroscopy (CIS) technique as a function of frequency (40 Hz-10 MHz) under different forward dc bias voltages (0-1 V). The CIS analysis demonstrates the contribution of bulk resistance in conduction mechanism and its dependency on forward dc bias voltages. The imaginary part of the impedance versus frequency curve exhibits the existence of relaxation peak which shifts with increasing dc forward bias voltages. The dc bias voltage-dependent ac and dc conductivity of the synthesized ZnS was studied on thin film structure. A possible hopping mechanism for electrical transport processes in the system was investigated. Finally, it is worth to mention that this analysis of bias voltage-dependent dielectric and transport properties of as-synthesized ZnS showed excellent properties for emerging energy applications.

  5. The relationship between bioelectrical impedance phase angle and subjective global assessment in advanced colorectal cancer

    OpenAIRE

    Gupta, Digant; Lis, Christopher G; Dahlk, Sadie L; King, Jessica; Vashi, Pankaj G; Grutsch, James F; Lammersfeld, Carolyn A

    2008-01-01

    Abstract Background Bioelectrical Impedance (BIA) derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA) is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. Methods We evaluated a case series of 73 stages III and IV colorectal cancer patients. Patients were classified as ei...

  6. Impedance analysis of GPCR-mediated changes in endothelial barrier function: overview and fundamental considerations for stable and reproducible measurements.

    Science.gov (United States)

    Stolwijk, Judith A; Matrougui, Khalid; Renken, Christian W; Trebak, Mohamed

    2015-10-01

    The past 20 years has seen significant growth in using impedance-based assays to understand the molecular underpinning of endothelial and epithelial barrier function in response to physiological agonists and pharmacological and toxicological compounds. Most studies on barrier function use G protein-coupled receptor (GPCR) agonists which couple to fast and transient changes in barrier properties. The power of impedance-based techniques such as electric cell-substrate impedance sensing (ECIS) resides in its ability to detect minute changes in cell layer integrity label-free and in real-time ranging from seconds to days. We provide a comprehensive overview of the biophysical principles, applications, and recent developments in impedance-based methodologies. Despite extensive application of impedance analysis in endothelial barrier research, little attention has been paid to data analysis and critical experimental variables, which are both essential for signal stability and reproducibility. We describe the rationale behind common ECIS data presentation and interpretation and illustrate practical guidelines to improve signal intensity by adapting technical parameters such as electrode layout, monitoring frequency, or parameter (resistance versus impedance magnitude). Moreover, we discuss the impact of experimental parameters, including cell source, liquid handling, and agonist preparation on signal intensity and kinetics. Our discussions are supported by experimental data obtained from human microvascular endothelial cells challenged with three GPCR agonists, thrombin, histamine, and sphingosine-1-phosphate.

  7. [Resting metabolic rate estimated by bioelectrical impedance analysis and its determinants in maintenance hemodialysis patients].

    Science.gov (United States)

    Da, J J; Peng, H Y; Lin, X; Shen, Y; Zhao, J Q; He, S; Zha, Y

    2018-03-27

    Objective: To explore the level of resting energy expenditure (REE) estimated by bioelectrical impedance analysis and the association of resting metabolic rate (RMR) with clinical related factors, and provide new ideas for improving protein energy wasting (PEW) in maintenance hemodialysis (MHD) patients. Methods: Seven hundred and sixty-five subjects receiving MHD between July 2015 and September 2016 in 11 hemodialysis centers in Guizhou province were enrolled in this cross-sectional study. Bioelectrical impedance analysis was used to measure RMR and body composition, such as lean body mass, fat mass and body cell mass (BCM). Baseline characteristics, routine blood test indexes and biochemical data of hemodialysis patients were collected. The level of RMR and body composition in hemodialysis patients was compared by gender grouping. Then the patients were divided into four groups according to the cutoff value of RMR quartile. Spearman correlation analysis and multiple linear regression analysis were used to analyze the relationships between RMR and clinical related factors. Results: The average age of MHD patients was (54.96±15.78) years and the duriation of dialysis was (42.3±9.0) months. The level of RMR in male patients (474 cases, 61.96%) was significantly higher than that in female patients [1 591(1 444, 1 764) kcal/d vs 1 226 (1 104, 1 354) kcal/d, P lean body mass ( P =0.193). Multiple linear regression analysis showed that RMR was positively correlated with body surface area (β=0.817) and lactate dehydrogenase (LDH) (β=0.198), and negatively correlated with age (β=-0.141), all P maintenance hemodialysis are associated with lactate dehydrogenase level, which may become a new index to evaluate energy consumption.

  8. Impedance measures in analysis and characterization of multistable structures subjected to harmonic excitation

    Science.gov (United States)

    Harne, Ryan L.; Goodpaster, Benjamin A.

    2018-01-01

    Structural components susceptible to adverse, post-buckled dynamic behaviors have long challenged the success of applications requiring lightweight, slender curved structures, while researchers have begun to leverage such bistable systems in emerging applications for novel energy attenuation and shape-changing properties. To expedite development and deployment of these built-up platforms containing post-buckled constituents, efficient approaches are required to complement time-consuming full-field models in the prediction of the near- and far-from-equilibrium dynamics. This research meets the need by introducing a semi-analytical model framework to enable the characterization of steady-state responses in multi degree-of-freedom (DOF) and multistable structural systems subjected to harmonic excitation. In so doing, the pathway for assessing impedance measures is created here so as to identify how energy travels and returns within built-up multistable structures. Verified by simulations and qualitatively validated by experiments, the analysis is shown to accurately reproduce both near- and far-from-equilibrium responses including different classes of energetic snap-through dynamics that only exist in such multistable structures. A first look at the impedance measures of different dynamic regimes reveals a connection between damping in multistable structures and the sustainability of far-from-equilibrium oscillations.

  9. Real-time impedance analysis of silica nanowire toxicity on epithelial breast cancer cells.

    Science.gov (United States)

    Alexander, Frank A; Huey, Eric G; Price, Dorielle T; Bhansali, Shekhar

    2012-12-21

    Silica nanowires have great potential for usage in the development of highly sensitive in vivo biosensors used for biomarker monitoring. However, careful analysis of nanowire toxicity is required prior to placing these sensors within the human body. This paper describes a real-time and quantitative analysis of nanowire cytotoxicity using impedance spectroscopy; improving upon studies that have utilized traditional endpoint assays. Silica nanowires were grown using the vapor liquid solid (VLS) method, mixed with Dulbecco's Modified Eagle Medium (DMEM) and exposed to Hs578T epithelial breast cancer cells at concentrations of 0 μg ml(-1), 1 μg ml(-1), 50 μg ml(-1) and 100 μg ml(-1). Real-time cellular responses to silica nanowires confirm that while not cytotoxic, silica nanowires at high concentrations (≥50 μg ml(-1)) are toxic to cells, and also suggest that cell death is due to mechanical disturbances of high numbers of nanowires.

  10. Design and Development of a Portable WiFi enabled BIA device

    International Nuclear Information System (INIS)

    Kriz'aj, D; Baloh, M; Zagar, T; Brajkovic, R

    2013-01-01

    A bioimpedance device (BIA) for evaluation of sarcopenia – age related muscle mass loss – is designed, developed and evaluated. The requirements were based on lightweight design, flexible and user enabled incorporation of measurement protocols and WiFi protocol for remote device control, full internet integration and fast development and usage of measurement protocols. The current design is based on usage of a microcontroller with integrated AD/DA converters. The prototype system was assembled and the operation and connectivity to different handheld devices and laptop computers was successfully tested. The designed BIA device can be accessed using TCP sockets and once the connection is established the data transfer runs successfully at the specified speed. The accuracy of currently developed prototype is about 5% for the impedance modulus and 5 deg. for the phase for the frequencies below 20 kHz with an unfiltered excitation signal and no additional amplifiers employed.

  11. BMI or BIA: Is Body Mass Index or Body Fat Mass a Better Predictor of Cardiovascular Risk in Overweight or Obese Children and Adolescents?

    Science.gov (United States)

    Bohn, Barbara; Müller, Manfred James; Simic-Schleicher, Gunter; Kiess, Wieland; Siegfried, Wolfgang; Oelert, Monika; Tuschy, Sabine; Berghem, Stefan; Holl, Reinhard W.

    2015-01-01

    Background Body fat (BF) percentiles for German children and adolescents have recently been published. This study aims to evaluate the association between bioelectrical impedance analysis(BIA)-derived BF and cardiovascular risk factors and to investigate whether BF is better suited than BMI in children and adolescents. Methods Data of 3,327 children and adolescents (BMI > 90th percentile) were included. Spearman's correlation and receiver operating characteristics (ROCs) were applied determining the associations between BMI or BF and cardiovascular risk factors (hypertension, dyslipidemia, elevated liver enzymes, abnormal carbohydrate metabolism). Area under the curve (AUC) was calculated to predict cardiovascular risk factors. Results A significant association between both obesity indices and hypertension was present (all p correlation with BMI was stronger (r = 0.22) compared to BF (r = 0.13). There were no differences between BMI and BF regarding their correlation with other cardiovascular risk factors. BF significantly predicted hypertension (AUC = 0.61), decreased HDL-cholesterol (AUC = 0.58), elevated LDL-cholesterol (AUC = 0.59), elevated liver enzymes (AUC = 0.61) (all p < 0.0001), and elevated triglycerides (AUC = 0.57, p < 0.05), but not abnormal carbohydrate metabolism (AUC = 0.54, p = 0.15). For the prediction of cardiovascular risk factors, no significant differences between BMI and BF were observed. Conclusion BIA-derived BF was not superior to BMI to predict cardiovascular risk factors in overweight or obese children and adolescents. PMID:26087841

  12. Electrochemical impedance spectroscopy of supercapacitors: A novel analysis approach using evolutionary programming

    Science.gov (United States)

    Oz, Alon; Hershkovitz, Shany; Tsur, Yoed

    2014-11-01

    In this contribution we present a novel approach to analyze impedance spectroscopy measurements of supercapacitors. Transforming the impedance data into frequency-dependent capacitance allows us to use Impedance Spectroscopy Genetic Programming (ISGP) in order to find the distribution function of relaxation times (DFRT) of the processes taking place in the tested device. Synthetic data was generated in order to demonstrate this technique and a model for supercapacitor ageing process has been obtained.

  13. Harmonic Active Filtering and Impedance-based Stability Analysis in Offshore Wind Power Plants

    DEFF Research Database (Denmark)

    Dhua, Debasish; Yang, Guangya; Zhang, Zhe

    2017-01-01

    installation and provides effectively similar functionality as passive filters. This work is focused on harmonic propagation studies in wind power plants, power quality evaluation at the point of connection and harmonic mitigation by active filtering. Finally, an impedance-based stability analysis......Nowadays, to eliminate harmonics injected by the wind turbines in offshore wind power plants there is a need to install passive filters. Moreover, the passive filters are not adaptive to harmonic profile changes due to topology changes, grid loading etc. Therefore, active filters in wind turbines...... are proposed as a flexible harmonic mitigation measure. The motivation of this study is to explore the possibility of embedding active filtering in wind turbine grid-side converters without having to change the system electrical infrastructure. The active filtering method can prevent additional equipment...

  14. Percent body fat and BMI in indigenous and mestizo children from South, Centre and North Mexico derived from bioimpedance analysis (BIA) and deuterium oxide dilution

    International Nuclear Information System (INIS)

    Valencia, Mauro E; Ramirez-Lopez, Erik; Ramos-Salas, Je; Bourges, Hector; Espinoza, Teresa

    2014-01-01

    Full text: Background. Body mass index (BMI) is an international standard to evaluate nutritional status but has the inability to distinguish fat mass from fat free mass, especially with regards to ethnicity. Mexico is the eight country in ethnic diversity in the world. The changes in fat mass and fat free mass offers the possibility to evaluate the effects of intervention programs in shorter periods. Objective. The purpose of the present study was to investigate the relationship between body composition and anthropometric characteristics of indigenous and mestizo Mexican children. Subject and Methods. A total of 1618 male and female indigenous (n = 498) and mestizo (n = 1120) children 7-9 years, were selected by stratified multiple stage cluster sampling. Indigenous groups and States were: Tarahumaras (Chihuahua), Mayos (Sonora), Nahuas (Puebla), Otomíes (Hidalgo), Tzotziles (Chiapas) and Mayas (Yucatan Peninsula). Mestizos form the same regions were included. Fat free mass and fat mass were obtained from a previously reported BIA cross validated equation using deuterium oxide dilution from 339 children from the same population, groups and regions. Results. The indigenous groups had 18.5 + 5.9 % fat compared to 23.5 + 8.4 in the mestizos (p<0.0001). Nahuas had the lowest % fat (p<0.0001) with 16.5 + 5.7, compared to Mayos, Tarahumaras and Mayas that had 18.6 + 6.2, 19.0 + 6.3 and 18.0 + 6.5 respectively. Mestizos form the Centre, North, and South had the highest levels of % body fat (p<0.001) with 25.4 + 7.7, 21.9 + 8.2, and 20.5 + 7.8, respectively. In indigenous children (n = 498) the 5th percentile (95% CI) corresponded to 9 (8,10) % body fat, while for Mestizos (n = 1120), the 5th percentile was 10 (9,11). Using this percentile, only one third of the children approximately of both groups would be classified as thin by WHO and IOTF classifications. Conclusion. Indigenous children had lower body fat than mestizos, however, the relationship of BMI to % body fat

  15. Combined evaluation of nutrition and hydration in dialysis patients with bioelectrical impedance vector analysis (BIVA).

    Science.gov (United States)

    Piccoli, Antonio; Codognotto, Marta; Piasentin, Paola; Naso, Agostino

    2014-08-01

    Body hydration changes continuously in hemodialysis patients. The Subjective Global Assessment (SGA) is used for the nutritional evaluation but it does not allow a direct evaluation of hydration. Bioelectrical impedance vector analysis (BIVA) is very sensitive to hydration. The potential of the combined evaluation of hydration and nutrition with SGA and BIVA is still lacking. Observational cross-sectional study on 130 (94 Male) uremic patients undergoing chronic hemodialysis three times a week. Nutritional status was evaluated with the SGA. Each subject was classified as SGA-A (normal nutritional status), SGA-B (moderate malnutrition), or SGA-C (severe malnutrition). Body hydration was evaluated with BIVA. The two vector components resistance (R) and reactance (Xc) were normalized by the subject's height and standardized as bivariate Z-score, i.e. Z(R) and Z(Xc). Undernutrition influenced impedance vector distribution both before and after a dialysis session. In pre-dialysis, the mean vector of SGA A was inside the 50% tolerance ellipse. In SGA B and C, Z(R) was increased and Z(Xc) decreased, indicating a progressive loss of soft tissue mass. Fluid removal with dialysis increased both Z(R) and Z(Xc) in SGA A and B but not in C. With ROC curve analysis on the slope of increase, we found the cutoff value of 27.8° below which undernutrition was present, either moderate or severe. The area under the ROC curve was 77.7° (95% CI 69.5-84.5, P hydration in each SGA category can be detected with BIVA. Copyright © 2013 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  16. The relationship between nocturnal polyuria and the distribution of body fluid: assessment by bioelectric impedance analysis.

    Science.gov (United States)

    Torimoto, Kazumasa; Hirayama, Akihide; Samma, Shoji; Yoshida, Katsunori; Fujimoto, Kiyohide; Hirao, Yoshihiko

    2009-01-01

    Increased nocturnal urinary volume is closely associated with nocturia. We investigated the relationship between nocturnal polyuria and the variation of body fluid distribution during the daytime using bioelectric impedance analysis. A total of 34 men older than 60 years were enrolled in this study. A frequency volume chart was recorded. Nocturnal polyuria was defined as a nocturnal urine volume per 24-hour production of greater than 0.35 (the nocturnal polyuria index). Bioelectric impedance analysis was performed 4 times daily at 8 and 11 a.m., and 5 and 9 p.m. using an InBody S20 body composition analyzer (BioSpace, Seoul, Korea). A significant difference was found in mean +/- SEM 24-hour urine production per fat-free mass between the groups with and without nocturnal polyuria (17.8 +/- 1.4 vs 7.7 +/- 0.9 ml/kg). The increase in fluid in the legs compared with the volume at 8 a.m. was significantly larger at 5 p.m., while there was no difference in the arms or trunk. Nocturnal urine volume significantly correlated with the difference in fluid volume in the legs (r = 0.527, p = 0.0019) and extracellular fluid volume (r = 0.3844, p = 0.0248) between the volumes at 8 a.m. and 9 p.m. Overproduction of urine per fat-free mass leads to nocturnal polyuria. Extracellular fluid accumulates as edema in the legs during the day in patients with nocturnal polyuria. The volume of accumulated extracellular fluid correlates with nocturnal urine volume. We suggest that leg edema is the source of nocturnal urine volume and decreasing edema may cure nocturnal polyuria.

  17. Automated impedance-manometry analysis detects esophageal motor dysfunction in patients who have non-obstructive dysphagia with normal manometry

    NARCIS (Netherlands)

    Nguyen, N. Q.; Holloway, R. H.; Smout, A. J.; Omari, T. I.

    2013-01-01

    Background  Automated integrated analysis of impedance and pressure signals has been reported to identify patients at risk of developing dysphagia post fundoplication. This study aimed to investigate this analysis in the evaluation of patients with non-obstructive dysphagia (NOD) and normal

  18. Impedance Scaling and Impedance Control

    International Nuclear Information System (INIS)

    Chou, W.; Griffin, J.

    1997-06-01

    When a machine becomes really large, such as the Very Large Hadron Collider (VLHC), of which the circumference could reach the order of megameters, beam instability could be an essential bottleneck. This paper studies the scaling of the instability threshold vs. machine size when the coupling impedance scales in a ''normal'' way. It is shown that the beam would be intrinsically unstable for the VLHC. As a possible solution to this problem, it is proposed to introduce local impedance inserts for controlling the machine impedance. In the longitudinal plane, this could be done by using a heavily detuned rf cavity (e.g., a biconical structure), which could provide large imaginary impedance with the right sign (i.e., inductive or capacitive) while keeping the real part small. In the transverse direction, a carefully designed variation of the cross section of a beam pipe could generate negative impedance that would partially compensate the transverse impedance in one plane

  19. Density-viscosity product of small-volume ionic liquid samples using quartz crystal impedance analysis.

    Science.gov (United States)

    McHale, Glen; Hardacre, Chris; Ge, Rile; Doy, Nicola; Allen, Ray W K; MacInnes, Jordan M; Bown, Mark R; Newton, Michael I

    2008-08-01

    Quartz crystal impedance analysis has been developed as a technique to assess whether room-temperature ionic liquids are Newtonian fluids and as a small-volume method for determining the values of their viscosity-density product, rho eta. Changes in the impedance spectrum of a 5-MHz fundamental frequency quartz crystal induced by a water-miscible room-temperature ionic liquid, 1-butyl-3-methylimiclazolium trifluoromethylsulfonate ([C4mim][OTf]), were measured. From coupled frequency shift and bandwidth changes as the concentration was varied from 0 to 100% ionic liquid, it was determined that this liquid provided a Newtonian response. A second water-immiscible ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C4mim][NTf2], with concentration varied using methanol, was tested and also found to provide a Newtonian response. In both cases, the values of the square root of the viscosity-density product deduced from the small-volume quartz crystal technique were consistent with those measured using a viscometer and density meter. The third harmonic of the crystal was found to provide the closest agreement between the two measurement methods; the pure ionic liquids had the largest difference of approximately 10%. In addition, 18 pure ionic liquids were tested, and for 11 of these, good-quality frequency shift and bandwidth data were obtained; these 12 all had a Newtonian response. The frequency shift of the third harmonic was found to vary linearly with square root of viscosity-density product of the pure ionic liquids up to a value of square root(rho eta) approximately 18 kg m(-2) s(-1/2), but with a slope 10% smaller than that predicted by the Kanazawa and Gordon equation. It is envisaged that the quartz crystal technique could be used in a high-throughput microfluidic system for characterizing ionic liquids.

  20. Impedance analysis of a disk-type SOFC using doped lanthanum gallate under power generation

    Science.gov (United States)

    Kato, Tohru; Nozaki, Ken; Negishi, Akira; Kato, Ken; Monma, Akihiko; Kaga, Yasuo; Nagata, Susumu; Takano, Kiyonami; Inagaki, Toru; Yoshida, Hiroyuki; Hosoi, Kei; Hoshino, Koji; Akbay, Taner; Akikusa, Jun

    Impedance measurements were carried out under practical power generation conditions in a disk-type SOFC, which may be utilized as a small-scale power generator. The tested cell was composed of doped lanthanum gallate (La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ) as the electrolyte, Sm 0.5Sr 0.5CoO 3 as the cathode electrode and Ni/Ce 0.8Sm 0.2O 2 cermet as the anode electrode. The cell impedance was measured between 10 mHz and 10 kHz by varying the fuel utilization and gas flow rate and plotted in complex impedance diagrams. The observed impedance shows a large semi-circular pattern on the low frequency side. The semi-circular impedance, having a noticeably low characteristic frequency between 0.13 and 0.4 Hz, comes from the change in gas composition, originally caused by the cell reaction. The change in impedance with the fuel utilization (load current) and the gas flow rate agreed qualitatively well with the theoretical predictions from a simulation. This impedance was dominant under high fuel-utilization power-generation conditions. The impedance, which described the activation polarizations in the electrode reactions, was comparatively small and scarcely changed with the change in fuel utilization (load current) and gas flow rate.

  1. Body composition measures of obese adolescents by the deuterium oxide dilution method and by bioelectrical impedance

    Directory of Open Access Journals (Sweden)

    C.M.M. Resende

    2011-11-01

    Full Text Available The objectives of the present study were to describe and compare the body composition variables determined by bioelectrical impedance (BIA and the deuterium dilution method (DDM, to identify possible correlations and agreement between the two methods, and to construct a linear regression model including anthropometric measures. Obese adolescents were evaluated by anthropometric measures, and body composition was assessed by BIA and DDM. Forty obese adolescents were included in the study. Comparison of the mean values for the following variables: fat body mass (FM; kg, fat-free mass (FFM; kg, and total body water (TBW; % determined by DDM and by BIA revealed significant differences. BIA overestimated FFM and TBW and underestimated FM. When compared with data provided by DDM, the BIA data presented a significant correlation with FFM (r = 0.89; P < 0.001, FM (r = 0.93; P < 0.001 and TBW (r = 0.62; P < 0.001. The Bland-Altman plot showed no agreement for FFM, FM or TBW between data provided by BIA and DDM. The linear regression models proposed in our study with respect to FFM, FM, and TBW were well adjusted. FFM obtained by DDM = 0.842 x FFM obtained by BIA. FM obtained by DDM = 0.855 x FM obtained by BIA + 0.152 x weight (kg. TBW obtained by DDM = 0.813 x TBW obtained by BIA. The body composition results of obese adolescents determined by DDM can be predicted by using the measures provided by BIA through a regression equation.

  2. Mediated oxidation of hydroquinone on poly(N-ethylcarbazole): Analysis of transport and kinetic phenomena by impedance techniques

    Energy Technology Data Exchange (ETDEWEB)

    Deslouis, C.; Tribollet, B. (Physique des Liquides et Electrochimie Lab., Univ. Pierre et Marie Curie, 75 - Paris (France)); Musiani, M.M. (Ist. di Polarografia ed Elettrochimica Preparativa del CNR, Padua (Italy))

    1990-09-01

    The oxidation of hydroquinone on Pt electrodes modified by electrosynthesized p-ethylcarbazole is studied in 5 M HClO{sub 4}. Electrohydrodynamical and a.c. impedance measurements yield the redox capacitance of the film and electron diffusivity D{sub E} with reasonable dependence on the thickness. D{sub E} values near to 10{sup -7} cm{sup 2} s{sup -1} confirm the average conductivity of this polymer. Change-transfer resistances in agreement with {alpha}=0.5 are measured. These results {alpha} posteriori justify the hypotheses put forward when developing the theoretical impedance model used for the analysis of the data. (orig.).

  3. 25 CFR 170.801 - What is the BIA Road Maintenance Program?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false What is the BIA Road Maintenance Program? 170.801 Section... ROADS PROGRAM BIA Road Maintenance § 170.801 What is the BIA Road Maintenance Program? The BIA Road... subpart contains a list of activities that are eligible for funding under the BIA road maintenance program. ...

  4. Impedance Analysis of the Conditioning of PBI–Based Electrode Membrane Assemblies for High Temperature PEM Fuel Cells

    DEFF Research Database (Denmark)

    Araya, Samuel Simon; Vang, Jakob Rabjerg; Andreasen, Søren Juhl

    2013-01-01

    This work analyses the conditioning of single fuel cell assemblies based on different membrane electrode assembly (MEA) types, produced by different methods. The analysis was done by means of electrochemical impedance spectroscopy, and the changes in the fitted resistances of the all the tested...

  5. Funkcje białek bakteriofagowych

    Directory of Open Access Journals (Sweden)

    Ewa Brzozowska

    2011-01-01

    Full Text Available Bakteriofagi (fagi stanowią naturalny czynnik regulujący liczebność populacji bakteryjnych w przyrodzie. Zainteresowanie bakteriofagami ciągle wzrasta ze względu na ich ogromną liczebność w naturalnym środowisku, a tym samym wpływ na funkcjonowanie organizmów żywych oraz zastosowanie w terapii przeciwko patogennym bakteriom opornym na stosowane antybiotyki. Za swoistość i za zjadliwość fagów wobec bakterii odpowiadają białka wchodzące w skład cząstki fagowej. Białkami tymi są adhezyny rozpoznające receptory na komórkach gospodarzy oraz enzymy degradujące określone struktury ściany komórkowej lub otoczki bakterii. Inne białka fagowe pełnią funkcję strukturalną, wchodząc w skład kapsydów. Białka te chronią fagowy kwas nukleinowy oraz umożliwiają przekazanie wirusowego genomu do wnętrza komórki bakteryjnej, a tym samym odpowiadają za proces infekcji i namnażania fagów potomnych. Enzymy fagowe są ważną grupą białek, które degradują struktury ścian i otoczek bakteryjnych od zewnętrznej, a także od wewnętrznej strony komórki gospodarza. Są to enzymy lityczne hydrolizujące komponenty cukrowe oraz białkowe. Bliższe poznanie natury bakteriofagów oraz pojawienie się lekooporności wśród patogennych bakterii, spowodowało wzrost zainteresowania fagami, jako czynnikami leczniczymi. Bakteriofagi coraz częściej wykorzystywane są także w innych dziedzinach życia człowieka. Testowano je nie tylko w terapii roślin, zwierząt i ludzi, ale także zaproponowano ich użycie do odkażania żywności i środowiska.

  6. Impedance cardiography: a comparison of cardiac output vs waveform analysis for assessing left ventricular systolic dysfunction.

    Science.gov (United States)

    DeMarzo, Arthur P; Kelly, Russell F; Calvin, James E

    2007-01-01

    Early detection of asymptomatic left ventricular systolic dysfunction (LVSD) is beneficial in managing heart failure. Recent studies have cast doubt on the usefulness of cardiac output as an indicator of LVSD. In impedance cardiography (ICG), the dZ/dt waveform has a systolic wave called the E wave. This study looked at measurements of the amplitude and area of the E wave compared with ICG-derived cardiac output, stroke volume, cardiac index, and stroke index as methods of assessing LVSD. ICG data were obtained from patients (n=26) admitted to a coronary care unit. Clinical LVSD severity was stratified into 4 groups (none, mild, moderate, and severe) based on echocardiography data and standard clinical assessment by a cardiologist blinded to ICG data. Statistical analysis showed that the E wave amplitude and area were better indicators of the level of LVSD than cardiac output, stroke volume, cardiac index, or stroke index. ICG waveform analysis has potential as a simple point-of-care test for detecting LVSD in asymptomatic patients at high risk for developing heart failure and for monitoring LVSD in patients being treated for heart failure.

  7. Quantitative impedance analysis of solid ionic conductors: Effects of electrode polarization

    Czech Academy of Sciences Publication Activity Database

    Patil, D.; Shimakawa, K.; Zima, Vítězslav; Wágner, T.

    2014-01-01

    Roč. 115, č. 14 (2014), "143707-1"-"143707-6" ISSN 0021-8979 Institutional support: RVO:61389013 Keywords : impedance * conductivity * ion conductors Subject RIV: CA - Inorganic Chemistry Impact factor: 2.183, year: 2014

  8. Electrode impedance analysis of chronic tungsten microwire neural implants: understanding abiotic vs. biotic contributions

    Directory of Open Access Journals (Sweden)

    Viswanath eSankar

    2014-05-01

    Full Text Available Changes in biotic and abiotic factors can be reflected in the complex impedance spectrum of the microelectrodes chronically implanted into the neural tissue. The recording surface of the tungsten electrode in vivo undergoes abiotic changes due to recording site corrosion and insulation delamination as well as biotic changes due to tissue encapsulation as a result of the foreign body immune response. We reported earlier that large changes in electrode impedance measured at 1 kHz were correlated with poor electrode functional performance, quantified through electrophysiological recordings during the chronic lifetime of the electrode. There is a need to identity the factors that contribute to the chronic impedance variation. In this work, we use numerical simulation and regression to equivalent circuit models to evaluate both the abiotic and biotic contributions to the impedance response over chronic implant duration. COMSOL® simulation of abiotic electrode morphology changes provide a possible explanation for the decrease in the electrode impedance at long implant duration while biotic changes play an important role in the large increase in impedance observed initially.

  9. Simulation Analysis of Transmission-Line Impedance Transformers for Petawatt-Class Pulsed Power Accelerators

    International Nuclear Information System (INIS)

    Hu Yixiang; Qiu Aici; Sun Fengju; Huang Tao; Cong Peitian; Wang Liangping; Zeng Jiangtao; Li Yan; Zhang Xinjun; Lei Tianshi

    2011-01-01

    Based on the transmission line code TLCODE, a 1D circuit model for a transmission-line impedance transformer was developed and the simulation results were compared with those in the literature. The model was used to quantify the efficiencies of voltage-transport, energy-transport and power-transport for a transmission-line impedance transformer as functions of ψ (the ratio of the output impedance to the input impedance of the transformer) and Γ (the ratio of the pulse width to the one-way transit time of the transformer) under a large scale of m (the coefficient of the generalized exponential impedance profile). Simulation results suggest that with the increase in Γ, from 0 to ∞, the power transport efficiency first increases and then decreases. The maximum power transport efficiency can reach 90% or even higher for an exponential impedance profile (m = 1). With a consideration of dissipative loss in the dielectric and electrodes of the transformer, two representative designs of the water-insulated transformer are investigated for the next generation of petawatt-class z-pinch drivers. It is found that the dissipative losses in the electrodes are negligibly small, below 0.1%, but the dissipative loss in the water dielectric is about 1% to 4%. (fusion engineering)

  10. Comparison of body fat in Brazilian adult females by bioelectrical impedance analysis

    International Nuclear Information System (INIS)

    Altamir, Vaz; Frère, Slaets Annie France; Leonardo, López Ramírez

    2012-01-01

    Body-fat is essential for human body, provided that its amount is at healthy levels. If in-excess body-fat is deleterious, its lack is otherwise also harmful. Estimated percent body-fat performed with commercially available devices measuring bioimpedance have many advantages, such as easy measurement and low cost. However, these measurements are based on standard models and equations that are not disclosed by manufacturers, and this leads to questioning the validity of these estimates for Brazilian females. The aim of this study was to compare electrical tetrapolar and octapolar impedance results obtained with commercially available equipment: Maltron BF-906 and OMRON 510-W. Data analysis involved descriptive and inferential statistics. Devices used in this study to estimate body fat quantity have not shown any significant differences in results; this is a major issue when selecting equipment based on three factors: study focus, available financial resources, and target population. Results obtained from the two devices have not shown any significant differences, which lead to the conclusion that either device may be reliably used.

  11. Alterations in body fluid content can be detected by bioelectrical impedance analysis.

    Science.gov (United States)

    Scheltinga, M R; Jacobs, D O; Kimbrough, T D; Wilmore, D W

    1991-05-01

    The electrical resistance across the whole body and its segments to the conduction of a weak alternating current was determined in human subjects under three different conditions: (1) during bed rest, (2) during infusion of 1 liter of saline, and (3) during donation of 1 unit of blood. During bed rest, extracellular and total body water were measured by dilution of bromide and heavy water, respectively. Electrical resistance obtained from electrodes placed on proximal portions of extremities ("proximal resistance") accounted for less than 50% of that determined by electrodes positioned on routinely used portions of a hand and foot ("whole body resistance"). Following saline infusion, resistance determined from the whole body and all its segments fell (P less than 0.001); the magnitude of the drop in both proximal and whole body resistance was inversely related to the volume of total body water (TBW) (r = -0.82, P less than 0.002, and r = -0.73, P less than 0.01, respectively). In contrast, blood donation was associated with significantly increased resistance at both measurement sites. TBW predicted from anthropometrics was inversely related to both proximal (r = -0.90, P less than 0.001) and whole body resistance (r = -0.75, P less than 0.001). Bioelectrical impedance analysis is a simple technique which may be useful in monitoring minimal alterations in TBW. Furthermore, altered fluid status may be predicted more accurately by changes in proximal resistance compared to changes in traditionally used whole body resistance.

  12. Electrochemical Impedance Analysis of a PEDOT:PSS-Based Textile Energy Storage Device

    Directory of Open Access Journals (Sweden)

    Ida Nuramdhani

    2017-12-01

    Full Text Available A textile-based energy storage device with electroactive PEDOT:PSS (poly(3,4-ethylenedioxythiophene/poly(4-styrenesulfonate polymer functioning as a solid-state polyelectrolyte has been developed. The device was fabricated on textile fabric with two plies of stainless-steel electroconductive yarn as the electrodes. In this study, cyclic voltammetry and electrochemical impedance analysis were used to investigate ionic and electronic activities in the bulk of PEDOT:PSS and at its interfaces with stainless steel yarn electrodes. The complex behavior of ionic and electronic origins was observed in the interfacial region between the conductive polymer and the electrodes. The migration and diffusion of the ions involved were confirmed by the presence of the Warburg element with a phase shift of 45° (n = 0.5. Two different equivalent circuit models were found by simulating the model with the experimental results: (QR(QR(QR for uncharged and (QR(QR(Q(RW for charged samples. The analyses also showed that the further the distance between electrodes, the lower the capacitance of the cell. The distribution of polymer on the cell surface also played important role to change the capacitance of the device. The results of this work may lead to a better understanding of the mechanism and how to improve the performance of the device.

  13. Bioelectrical impedance vector analysis for evaluating zinc supplementation in prepubertal and healthy children

    Directory of Open Access Journals (Sweden)

    Márcia Marília Gomes Dantas

    2015-09-01

    Full Text Available Background: The prevalence of abnormal nutritional status has increased in children and adolescents. Nutritional assessment is important for monitoring the health and nutritional status. Bioelectrical impedance vector analysis (BIVA combines changes in tissue hydration and structure and body composition that can be assessed. Objectives: The objective of this study was to use BIVA to evaluate nutritional status in 60 prepubertal children, aged between 8 and 9 years, supplemented with zinc, to detect possible changes in body composition. Design: We performed a randomized, controlled, triple-blind study. The children were divided into the control group (CG; sorbitol 10%, n=29 or the experimental group (EG; 10 mg Zn/day, n=31, and the duration of the experiment was 3 months. Anthropometric assessments were performed for all of the children. Results: The body mass index-for-age increased after oral zinc supplementation in the EG (p=0.005. BIVA indicated that the CG demonstrated a tendency for dehydration and decreased soft tissue and the EG demonstrated a tendency for increased soft tissue, primarily the fat-free mass. After analyses of BIVA ellipses, we observed that this method could detect improvements in body composition in healthy children supplemented with zinc. Conclusions: These results suggest that BIVA could be an auxiliary method for studying a small population undergoing zinc intervention.

  14. Correlation between ultrafiltration rate and phase angle measured by BIA in chronic kidney disease patients on regular hemodialysis

    Science.gov (United States)

    Nasution, B. R.; Lubis, A. R.

    2018-03-01

    Chronic Kidney Disease (CKD) patients with regular hemodialysis have high rates of morbidity and mortality that may be related to the hemodynamic effects of rapid UFR and low PhA value. In this study, we investigated whether high UFR is associated with a low value of PhA thus indirectly affect the risk of morbidity and mortality. UFR and Bioelectrical Impedance Analysis (BIA) examination on 92 subjects were recorded shortly after HD and analyzed by using Pearson correlation test. Multivariate analysis was also conducted to identify several factors that can affect the value of Phase angle. The number of HD regular CKD patients with PhA<4 based on the division of the UFR (cc/kg/h) <10, 10-13, ≥ 13, respectively were3, 10 and 6, whereas patients with ≥ 4 PhA <10, 10-13, ≥ 13respectively were 60, 11, and 2. The results showed a significant relationship between UFR with PhA. In CKD patients with regular HD, UFR has aninverse relationship with the value of PhA. After multivariate analysis, the UFR and the etiology of HD are still significantly affect the value of PhA. UFR optimal value in patients with CKD with regular HD is <10 cc/kg/h.

  15. Automated impedance-manometry analysis detects esophageal motor dysfunction in patients who have non-obstructive dysphagia with normal manometry.

    Science.gov (United States)

    Nguyen, N Q; Holloway, R H; Smout, A J; Omari, T I

    2013-03-01

    Automated integrated analysis of impedance and pressure signals has been reported to identify patients at risk of developing dysphagia post fundoplication. This study aimed to investigate this analysis in the evaluation of patients with non-obstructive dysphagia (NOD) and normal manometry (NOD/NM). Combined impedance-manometry was performed in 42 patients (27F : 15M; 56.2 ± 5.1 years) and compared with that of 24 healthy subjects (8F : 16M; 48.2 ± 2.9 years). Both liquid and viscous boluses were tested. MATLAB-based algorithms defined the median intrabolus pressure (IBP), IBP slope, peak pressure (PP), and timing of bolus flow relative to peak pressure (TNadImp-PP). An index of pressure and flow (PFI) in the distal esophagus was derived from these variables. Diagnoses based on conventional manometric assessment: diffuse spasm (n = 5), non-specific motor disorders (n = 19), and normal (n = 11). Patients with achalasia (n = 7) were excluded from automated impedance-manometry (AIM) analysis. Only 2/11 (18%) patients with NOD/NM had evidence of flow abnormality on conventional impedance analysis. Several variables derived by integrated impedance-pressure analysis were significantly different in patients as compared with healthy: higher PNadImp (P < 0.01), IBP (P < 0.01) and IBP slope (P < 0.05), and shorter TNadImp_PP (P = 0.01). The PFI of NOD/NM patients was significantly higher than that in healthy (liquid: 6.7 vs 1.2, P = 0.02; viscous: 27.1 vs 5.7, P < 0.001) and 9/11 NOD/NM patients had abnormal PFI. Overall, the addition of AIM analysis provided diagnoses and/or a plausible explanation in 95% (40/42) of patients who presented with NOD. Compared with conventional pressure-impedance assessment, integrated analysis is more sensitive in detecting subtle abnormalities in esophageal function in patients with NOD and normal manometry. © 2012 Blackwell Publishing Ltd.

  16. Design and performance analysis of position-based impedance control for an electrohydrostatic actuation system

    Directory of Open Access Journals (Sweden)

    Yongling FU

    2018-03-01

    Full Text Available Electrohydrostatic actuator (EHA is a type of power-by-wire actuator that is widely implemented in the aerospace industry for flight control, landing gears, thrust reversers, thrust vector control, and space robots. This paper presents the development and evaluation of position-based impedance control (PBIC for an EHA. Impedance control provides the actuator with compliance and facilitates the interaction with the environment. Most impedance control applications utilize electrical or valve-controlled hydraulic actuators, whereas this work realizes impedance control via a compact and efficient EHA. The structures of the EHA and PBIC are firstly introduced. A mathematical model of the actuation system is established, and values of its coefficients are identified by particle swarm optimization. This model facilitates the development of a position controller and the selection of target impedance parameters. A nonlinear proportional-integral position controller is developed for the EHA to achieve the accurate positioning requirement of PBIC. The controller compensates for the adverse effect of stiction, and a position accuracy of 0.08 mm is attained. Various experimental results are presented to verify the applicability of PBIC to the EHA. The compliance of the actuator is demonstrated in an impact test. Keywords: Actuation system, Aerospace, Electrohydrostatic actuator, Force control, Nonlinear dynamics, Particle swarm optimization, Position control

  17. Electrochemical impedance spectroscopy analysis of a thin polymer film-based micro-direct methanol fuel cell

    Science.gov (United States)

    Schulz, Tobias; Weinmüller, Christian; Nabavi, Majid; Poulikakos, Dimos

    A single cell micro-direct methanol fuel cell (micro-DMFC) was investigated using electrochemical impedance spectroscopy. The electrodes consisted of thin, flexible polymer (SU8) film microchannel structures fabricated in-house using microfabrication techniques. AC impedance spectroscopy was used to separate contributions to the overall cell polarization from the anode, cathode and membrane. A clear distinction between the different electrochemical phenomena occurring in the micro-DMFC, especially the distinction between double layer charging and Faradaic reactions was shown. The effect of fuel flow rate, temperature, and anode flow channel structure on the impedance of the electrode reactions and membrane/electrode double layer charging were investigated. Analysis of impedance data revealed that the performance of the test cell was largely limited by the presence of intermediate carbon monoxide in the anode reaction. Higher temperatures increase cell performance by enabling intermediate CO to be oxidized at much higher rates. The results also revealed that serpentine anode flow microchannels show a lower tendency to intermediate CO coverage and a more stable cell behavior than parallel microchannels.

  18. Impedance-spectroscopy analysis and piezoelectric properties of Pb2KNb5O15 ceramics

    International Nuclear Information System (INIS)

    Rao, K. Sambasiva; Murali Krishna, P.; Swarna Latha, T.; Madhava Prasad, D.

    2006-01-01

    Preparation, dielectric, piezoelectric, hysteresis, impedance spectroscopy and AC conductivity studies in the Pb 0.8 K 0.4 Nb 2 O 6 ferroelectric ceramic have been presented. The Pb 1-x K 2x Nb 2 O 6 (PKN) characterized for ferroelectric and impedance spectroscopy studies from room temperature to 600 deg. C. The sample shows a single phase with orthorhombic structure from X-ray diffraction studies. The Cole-Cole plots and electric modulus plots at different temperatures are drawn. The results obtained from the impedance spectroscopy are analyzed, to understand the conductivity behavior of PKN. The piezoelectric constant, d 33 , has been found to be 75 x 10 -12 C/N

  19. Prevalence of rheumatoid cachexia assessed by bioelectrical impedance vector analysis and its relation with physical function.

    Science.gov (United States)

    Santillán-Díaz, Cira; Ramírez-Sánchez, Noemi; Espinosa-Morales, Rolando; Orea-Tejeda, Arturo; Llorente, Luis; Rodríguez-Guevara, Gerardo; Castillo-Martínez, Lilia

    2018-03-01

    Rheumatoid arthritis (RA) patients frequently have changes in their body composition, with a decrease in muscle mass and an increase in fat mass, a syndrome that is termed rheumatoid cachexia (RC). The prevalence of this nutritional alteration is not well known; there is as yet no consensus, seeing as it depends on the methods, techniques, and cutoff points that are used for its diagnosis. The main aim of this study was to identify RC through assessment by bioelectrical impedance vector analysis (BIVA) and its association with metabolic causes, physical function, and the main disease status, among others. The prevalence of RC was identified in those subjects who fell outside the right lower quadrant of the reference curve of RXc graph of BIVA. Clinical, anthropometric, biochemical and physical activity, emotional status, and diet markers were also evaluated. Ninety-four patients were included (92.55% women). The prevalence of RC assessed by BIVA was 21.28%. BIVA-cachexia patients had a lesser value of handgrip strength vs. patients without BIVA-cachexia 10.2 kg (7.2-13.4) vs. 14.7 kg (9.6-19), p = 0.0062. Disability and folic acid with methotrexate consumption are related to BIVA-cachexia ((OR 4.69, 95% CI 1.33, 16.54, p = 0.016) and (OR 0.19, 95%CI 0.058, 0.651, p = 0.008), respectively). BIVA could represent a valuable tool to assess presence of RC. It is important that RA patients have physical therapy to improve their nutritional status.

  20. Electrochemical bond cleavage in pesticide ioxynil. Kinetic analysis by voltammetry and impedance spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Sokolová, R.; Giannarelli, S.; Fanelli, N.; Pospíšil, Lubomír

    2017-01-01

    Roč. 49, SI C (2017), s. 134-138 ISSN 0324-1130 Institutional support: RVO:61388963 Keywords : electrochemical impedance spectroscopy * rate constant * self-protonation * faradaic phase angle * halogen cleavage * EC processes fitting Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 0.238, year: 2016

  1. Electrochemical bond cleavage in pesticide ioxynil. Kinetic analysis by voltammetry and impedance spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Sokolová, Romana; Giannarelli, S.; Fanelli, N.; Pospíšil, Lubomír

    2017-01-01

    Roč. 49, C (2017), s. 134-138 ISSN 0324-1130 R&D Projects: GA ČR(CZ) GA14-05180S Institutional support: RVO:61388955 Keywords : electrochemical impedance spectroscopy * rate constant * self-protonation Subject RIV: CG - Electrochemistry OBOR OECD: Physical chemistry Impact factor: 0.238, year: 2016

  2. Bio-impedance analysis for appendicular skeletal muscle mass assessment in (pre-) frail elderly people

    NARCIS (Netherlands)

    Baar, van H.; Hulshof, P.J.M.; Tieland, C.A.B.; Groot, de C.P.G.M.

    2015-01-01

    Background & aims Screening populations for skeletal muscle mass (SMM) is important for early detection of sarcopenia. Our aim was to develop an age specific bio-impedance (BI) prediction equation for the assessment of appendicular skeletal muscle mass (ASMM) in (pre-) frail elderly people aged

  3. Impedance-based Analysis of DC Link Control in Voltage Source Rectifiers

    DEFF Research Database (Denmark)

    Lu, Dapeng; Wang, Xiongfei; Blaabjerg, Frede

    2018-01-01

    This paper analyzes the dynamics influences of the outer dc link control in the voltage source rectifiers based on the impedance model. The ac-dc interactions are firstly presented by means of full order small signal model in dq frame, which shows the input voltage and load condition are the two...

  4. Application of the Method of Auxiliary Sources for the Analysis of Electromagnetic Scattering by Impedance Spheres

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza; Breinbjerg, Olav

    2002-01-01

    The Method of Auxiliary Sources (MAS) is applied to 3D scattering problems involving spherical impedance scatterers. The MAS results are compared with the reference spherical wave expansion (SWE) solution. It is demonstrated that good agreement is achieved between the MAS and SWE results....

  5. Impedance budget and beam stability analysis of the Fermilab Main Injector

    International Nuclear Information System (INIS)

    Martens, M.A.; Ng, K.Y.

    1993-05-01

    The impedance budget of the Fermilab Main Injector (MI) is estimated, which includes the contributions from the resistive walls, bellows, rf cavities, steps, Lambertsons, etc. Beam stability during ramping and bunch coalescence is analyzed. The transverse resistive-wall coupled bunch growth is found to be somewhat worse than the situation in the Main Ring (MR)

  6. Fast BIA-amperometric determination of isoniazid in tablets.

    Science.gov (United States)

    Quintino, Maria S M; Angnes, Lúcio

    2006-09-26

    This paper proposes a new, fast and precise method to analyze isoniazid based on the electrochemical oxidation of the analyte at a glassy carbon electrode in 0.1M NaOH. The quantification was performed utilizing amperometry associated with batch injection analysis (BIA) technique. Fast sequential analysis (60 determinations h(-1)) in an unusually wide linear dynamic range (from 2.5 x 10(-8) to 1.0 x 10(-3)M), with high sensitivity and low limits of detection (4.1 x 10(-9)M) and quantification (1.4 x 10(-8)M), was achieved. Such characteristics allied to a good repeatability of the current responses (relative standard deviation of 0.79% for 30 measurements), were explored for the specific determination of isoniazid in isoniazid-rifampin tablet.

  7. 25 CFR 103.14 - Can BIA request additional information?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Can BIA request additional information? 103.14 Section 103.14 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR FINANCIAL ACTIVITIES LOAN GUARANTY, INSURANCE, AND INTEREST SUBSIDY How a Lender Obtains a Loan Guaranty or Insurance Coverage § 103.14 Can BIA...

  8. Large polaron tunneling, magnetic and impedance analysis of magnesium ferrite nanocrystallite

    Energy Technology Data Exchange (ETDEWEB)

    Mahato, Dev K., E-mail: drdevkumar@yahoo.com [Department of Physics, National Institute of Technology Patna, Patna 800 005 (India); Majumder, Sumit [Department of Physics, Jadavpur University, Kolkata 700032 (India); Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Banerjee, S. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)

    2017-08-15

    Graphical abstract: The diffraction peaks corresponding to the planes (111), (220), (311), (222), (400), (422), (511), (440), (620), (533) and (444) provide a clear evidence for the formation of spinel structure of the ferrites. The lattice parameter ‘a’ determined as 8.392 Å matches well with JCPDS (73-2410) file for MgFe{sub 2}O{sub 4.} The volume of the unit cell is 591.012 Å{sup 3}. The crystallite size of the synthesized powder estimated from X-ray peak broadening of (311) highest intensity diffraction peak using Scherer formula was 56.4 nm. - Highlights: • Both the grain and grain boundaries contribution to conductivity of the Mg-ferrite has been observed. • Polydispersive nature of the material is checked using Cole – Cole relation. • The ac conductivity of magnesium ferrite followed σ{sub ac} ∝ ω{sup n} dependence. • The variation of the exponent ‘n’ with temperature suggests that overlapping large polaron tunnelling is the dominant conduction mechanism. • The superparamagnetic behavior of this Mg-ferrite has been observed for sample S1 annealed at 500 °C. - Abstract: Single phase MgFe{sub 2}O{sub 4} (MFO) ferrite was prepared through sol-gel auto-combustion route. The Rietveld analysis of X-ray patterns reveals that our samples are single phase. The increase in average particle size with annealing temperature and formation of nanoparticle agglomerates is observed in MgFe{sub 2}O{sub 4}. The structural morphology of the nanoparticles is studied using Scanning Electron Microscopy (SEM). Formation of spinel structure is confirmed using Fourier transform infrared spectroscopy (FTIR). The Zero-Field-Cooled (ZFC) and Field-Cooled (FC) magnetization measurements show the maximum irreversibility at 700 °C annealing temperature. The formation of a maximum at blocking temperature, T{sub B}∼ 180 K for sample annealed at 500 °C in the ZFC curve shows the superparamagnetic behavior of the sample. The increase of saturation magnetism (M

  9. Impact of hemodialysis on dual X-ray absorptiometry, bioelectrical impedance measurements, and anthropometry

    DEFF Research Database (Denmark)

    Abrahamsen, Bo; Hansen, T B; Høgsberg, I M

    1996-01-01

    ), bioelectrical impedance analysis (BIA), and simple anthropometry in 19 patients (9 women and 10 men, mean age 46 y) before and after hemodialysis, removing 0.9-4.3 L (x: 2.8L) of ultrafiltrate. The reduction in fat-free mass (FFM) measured by DXA was highly correlated with the ultrafiltrate, as determined...... by the reduction in gravimetric weight (r = 0.975, P FFM reductions (r = 0.66, P ..., was estimated to be 0.6% lower after dialysis. None of the simple anthropometric measurements correlated significantly with the reduction in FFM. In an unmodified clinical setting, DXA appears to be superior to other simple noninvasive methods for determining body composition, particularly when the emphasis...

  10. Analysis and Design of an Energy Regenerative Snubber for Magnetically Coupled Impedance Source Converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Abdelhakim, Ahmed; Siwakoti, Yam

    2018-01-01

    Magnetically coupled impedance source (MCIS) converters are prone to high voltage spikes across the inverter bridge (or dc-link) due to the presence of leakage and stray inductances in the high frequency loop. The problem manifolds because of a shoot-through state in impedance source converters......, but the solutions are not generic (i.e. structure-oriented) and they are quite lossy with intuitive modification in the circuit itself, resulting in significant changes in the performance of the power converter (e.g. increase in components stresses). To address this concern, a general passive regenerative inductor......-capacitor-diode (L-C-D) snubber is presented in this paper for all MCIS converters without any modification in the original circuit. The proposed circuit rechannel the leakage energy of the coupled magnetics and feedback it to input or network itself, which does not only avoid extreme voltage spikes across...

  11. Analysis of Magnetically-Coupled Impedance Source Three-Phase Four-Switch Inverters

    DEFF Research Database (Denmark)

    Li, Kerui; Abdelhakim, Ahmed; Yang, Yongheng

    2017-01-01

    In this paper, magnetically-coupled impedance source (MCIS) three-phase four-switch inverters are introduced for renewable energy applications. This inverter utilizes two single-phase MCIS inverters to obtain a three-phase output, where less component-count is achieved in order to reduce the inve......In this paper, magnetically-coupled impedance source (MCIS) three-phase four-switch inverters are introduced for renewable energy applications. This inverter utilizes two single-phase MCIS inverters to obtain a three-phase output, where less component-count is achieved in order to reduce...... the inverter volume. On the other hand, as a result of the reduced number of switches, the proposed inverter suffers from higher voltage stresses. The MCIS inverters are first reviewed. Then, the modulation and operation principle of the MCIS three-phase inverter topology are introduced before sizing...

  12. Numerical analysis on effective electric field penetration depth for interdigital impedance sensor

    International Nuclear Information System (INIS)

    Kim, Chon-ung; Jong, Hakchol; Ro, Cholwu; Pak, Gilhung; Im, Songil; Li, Guofeng; Li, Jie; Song, Yunho

    2013-01-01

    Interdigital (finger-like) electrodes are widely used for electrical impedance and capacitance tomography of composite dielectric materials and complex insulating structures. Because of their advantages, they are now effectively introduced as capacitance sensors into a variety of industrial branches, agriculture, medical science, biological engineering, military branches, etc. In order to effectively apply the so-called interdigital impedance sensors in practice, of great importance is to optimize the sensor design parameters such as the electric field penetration depth, signal strength and so on. The general design principles of the interdigital capacitance sensor have been discussed for a long time by many researchers. However, there is no consensus on the definition of the effective electric field penetration depth of interdigital electrode. This paper discusses how to determine the effective electric field penetration depth of interdigital sensor on the basis of the refractive principle of electric field intensity and the FEM analyses of electric field distribution and capacitance for the sensor model.

  13. Development of an Algorithm for Automatic Analysis of the Impedance Spectrum Based on a Measurement Model

    Science.gov (United States)

    Kobayashi, Kiyoshi; Suzuki, Tohru S.

    2018-03-01

    A new algorithm for the automatic estimation of an equivalent circuit and the subsequent parameter optimization is developed by combining the data-mining concept and complex least-squares method. In this algorithm, the program generates an initial equivalent-circuit model based on the sampling data and then attempts to optimize the parameters. The basic hypothesis is that the measured impedance spectrum can be reproduced by the sum of the partial-impedance spectra presented by the resistor, inductor, resistor connected in parallel to a capacitor, and resistor connected in parallel to an inductor. The adequacy of the model is determined by using a simple artificial-intelligence function, which is applied to the output function of the Levenberg-Marquardt module. From the iteration of model modifications, the program finds an adequate equivalent-circuit model without any user input to the equivalent-circuit model.

  14. Diffusion and Gas Conversion Analysis of Solid Oxide Fuel Cells at Loads via AC Impedance

    Directory of Open Access Journals (Sweden)

    Robert U. Payne

    2011-01-01

    Full Text Available Impedance measurements were conducted under practical load conditions in solid oxide fuel cells of differing sizes. For a 2 cm2 button cell, impedance spectra data were separately measured for the anode, cathode, and total cell. Improved equivalent circuit models are proposed and applied to simulate each of measured impedance data. Circuit elements related to the chemical and physical processes have been added to the total-cell model to account for an extra relaxation process in the spectra not measured at either electrode. The processes to which elements are attributed have been deduced by varying cell temperature, load current, and hydrogen concentration. Spectra data were also obtained for a planar stack of five 61 cm2 cells and the individual cells therein, which were fitted to a simplified equivalent circuit model of the total button cell. Similar to the button cell, the planar cells and stack exhibit a pronounced low-frequency relaxation process, which has been attributed to concentration losses, that is, the combined effects of diffusion and gas conversion. The simplified total-cell model approximates well the dynamic behavior of the SOFC cells and the whole stack.

  15. Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry.

    Science.gov (United States)

    Rae, L S; Vankan, D M; Rand, J S; Flickinger, E A; Ward, L C

    2016-06-01

    Thirty-five healthy, neutered, mixed breed dogs were used to determine the ability of multifrequency bioelectrical impedance analysis (MFBIA) to predict accurately fat-free mass (FFM) in dogs using dual energy X-ray absorptiometry (DXA)-measured FFM as reference. A second aim was to compare MFBIA predictions with morphometric predictions. MFBIA-based predictors provided an accurate measure of FFM, within 1.5% when compared to DXA-derived FFM, in normal weight dogs. FFM estimates were most highly correlated with DXA-measured FFM when the prediction equation included resistance quotient, bodyweight, and body condition score. At the population level, the inclusion of impedance as a predictor variable did not add substantially to the predictive power achieved with morphometric variables alone; in individual dogs, impedance predictors were more valuable than morphometric predictors. These results indicate that, following further validation, MFBIA could provide a useful tool in clinical practice to objectively measure FFM in canine patients and help improve compliance with prevention and treatment programs for obesity in dogs. Copyright © 2016. Published by Elsevier Ltd.

  16. 25 CFR 170.803 - What facilities are eligible under the BIA Road Maintenance Program?

    Science.gov (United States)

    2010-04-01

    ... AND WATER INDIAN RESERVATION ROADS PROGRAM BIA Road Maintenance § 170.803 What facilities are eligible under the BIA Road Maintenance Program? (a) The following public transportation facilities are eligible for maintenance under the BIA Road Maintenance Program: (1) BIA transportation facilities listed in...

  17. 25 CFR 170.804 - How is BIA's Road Maintenance Program related to the IRR Program?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false How is BIA's Road Maintenance Program related to the IRR... WATER INDIAN RESERVATION ROADS PROGRAM BIA Road Maintenance § 170.804 How is BIA's Road Maintenance Program related to the IRR Program? The following chart illustrates how BIA's Road Maintenance Program is...

  18. Effects of diabetes and gender on mechanical properties of the arterial system in rats: aortic impedance analysis.

    Science.gov (United States)

    Chang, Kuo-Chu; Hsu, Kwan-Lih; Tseng, Yung-Zu

    2003-01-01

    We determined the effects of diabetes and gender on the physical properties of the vasculature in streptozotocin (STZ)-treated rats based on the aortic input impedance analysis. Rats given STZ 65 mg/kg i.v. were compared with untreated age-matched controls. Pulsatile aortic pressure and flow signals were measured and were then subjected to Fourier transformation for the analysis of aortic input impedance. Wave transit time was determined using the impulse response function of the filtered aortic input impedance spectra. Male but not female diabetic rats exhibited an increase in cardiac output in the absence of any significant changes in arterial blood pressure, resulting in a decline in total peripheral resistance. However, in each gender group, diabetes contributed to an increase in wave reflection factor, from 0.47 +/- 0.04 to 0.84 +/- 0.03 in males and from 0.46 +/- 0.03 to 0.81 +/- 0.03 in females. Diabetic rats had reduced wave transit time, at 18.82 +/- 0.60 vs 21.34 +/- 0.51 msec in males and at 19.63 +/- 0.37 vs 22.74 +/- 0.57 msec in females. Changes in wave transit time and reflection factor indicate that diabetes can modify the timing and magnitude of the wave reflection in the rat arterial system. Meanwhile, diabetes produced a fall in aortic characteristic impedance from 0.023 +/- 0.002 to 0.009 +/- 0.001 mmHg/min/kg/ml in males and from 0.028 +/- 0.002 to 0.014 +/- 0.001 mmHg/min/kg/ml in females. With unaltered aortic pressure, both the diminished aortic characteristic impedance and wave transit time suggest that the muscle inactivation in diabetes may occur in aortas and large arteries and may cause a detriment to the aortic distensibility in rats with either sex. We conclude that only rats with male gender diabetes produce a detriment to the physical properties of the resistance arterioles. In spite of male or female gender, diabetes decreases the aortic distensibility and impairs the wave reflection phenomenon in the rat arterial system.

  19. An analysis of electrical impedance tomography with applications to Tikhonov regularization

    KAUST Repository

    Jin, Bangti

    2012-01-16

    This paper analyzes the continuum model/complete electrode model in the electrical impedance tomography inverse problem of determining the conductivity parameter from boundary measurements. The continuity and differentiability of the forward operator with respect to the conductivity parameter in L p-norms are proved. These analytical results are applied to several popular regularization formulations, which incorporate a priori information of smoothness/sparsity on the inhomogeneity through Tikhonov regularization, for both linearized and nonlinear models. Some important properties, e.g., existence, stability, consistency and convergence rates, are established. This provides some theoretical justifications of their practical usage. © EDP Sciences, SMAI, 2012.

  20. Sensitivity analysis of magnetic field measurements for magnetic resonance electrical impedance tomography (MREIT)

    DEFF Research Database (Denmark)

    Göksu, Cihan; Scheffler, Klaus; Ehses, Philipp

    2017-01-01

    Purpose: Clinical use of magnetic resonance electrical impedance tomography (MREIT) still requires significant sensitivity improvements. Here, the measurement of the current-induced magnetic field (DBz,c) is improved using systematic efficiency analyses and optimization of multi-echo spin echo...... (MESE) and steady-state free precession free induction decay (SSFP-FID) sequences. Theory and Methods: Considering T1, T2, and T 2 relaxation in the signal-to-noise ratios (SNRs) of the MR magnitude images, the efficiency of MESE and SSFP-FID MREIT experiments, and its dependence on the sequence...

  1. Impedance analysis of DNA and DNA-drug interactions on thin mercury film electrodes

    Czech Academy of Sciences Publication Activity Database

    Hasoň, Stanislav; Dvořák, Jakub; Jelen, František; Vetterl, Vladimír

    2002-01-01

    Roč. 32, č. 2 (2002), s. 167-179 ISSN 1040-8347 R&D Projects: GA AV ČR IAA4004901; GA AV ČR IAA4004002; GA AV ČR IBS5004107 Grant - others:GA FRVŠ(XC) G40583; GA FRVŠ(XC) F40564 Institutional research plan: CEZ:AV0Z5004920 Keywords : electrochemical impedance spectroscopy * intercalators * DNA at electrode surface Subject RIV: BO - Biophysics Impact factor: 2.074, year: 2002

  2. An analysis of electrical impedance tomography with applications to Tikhonov regularization

    KAUST Repository

    Jin, Bangti; Maass, Peter

    2012-01-01

    This paper analyzes the continuum model/complete electrode model in the electrical impedance tomography inverse problem of determining the conductivity parameter from boundary measurements. The continuity and differentiability of the forward operator with respect to the conductivity parameter in L p-norms are proved. These analytical results are applied to several popular regularization formulations, which incorporate a priori information of smoothness/sparsity on the inhomogeneity through Tikhonov regularization, for both linearized and nonlinear models. Some important properties, e.g., existence, stability, consistency and convergence rates, are established. This provides some theoretical justifications of their practical usage. © EDP Sciences, SMAI, 2012.

  3. Validity of segmental bioelectrical impedance analysis for estimating fat-free mass in children including overweight individuals.

    Science.gov (United States)

    Ohta, Megumi; Midorikawa, Taishi; Hikihara, Yuki; Masuo, Yoshihisa; Sakamoto, Shizuo; Torii, Suguru; Kawakami, Yasuo; Fukunaga, Tetsuo; Kanehisa, Hiroaki

    2017-02-01

    This study examined the validity of segmental bioelectrical impedance (BI) analysis for predicting the fat-free masses (FFMs) of whole-body and body segments in children including overweight individuals. The FFM and impedance (Z) values of arms, trunk, legs, and whole body were determined using a dual-energy X-ray absorptiometry and segmental BI analyses, respectively, in 149 boys and girls aged 6 to 12 years, who were divided into model-development (n = 74), cross-validation (n = 35), and overweight (n = 40) groups. Simple regression analysis was applied to (length) 2 /Z (BI index) for each of the whole-body and 3 segments to develop the prediction equations of the measured FFM of the related body part. In the model-development group, the BI index of each of the 3 segments and whole body was significantly correlated to the measured FFM (R 2 = 0.867-0.932, standard error of estimation = 0.18-1.44 kg (5.9%-8.7%)). There was no significant difference between the measured and predicted FFM values without systematic error. The application of each equation derived in the model-development group to the cross-validation and overweight groups did not produce significant differences between the measured and predicted FFM values and systematic errors, with an exception that the arm FFM in the overweight group was overestimated. Segmental bioelectrical impedance analysis is useful for predicting the FFM of each of whole-body and body segments in children including overweight individuals, although the application for estimating arm FFM in overweight individuals requires a certain modification.

  4. 3-D seismic response analysis of liquid-tank-foundation system by using BEM-FEM-impedance function combination

    International Nuclear Information System (INIS)

    Cho, Eu-Kyeong; Park, Jung-Il; Lee, Jong-Rim

    1995-01-01

    A new analytic scheme to resolve the liquid-soil-structure interaction problem in cylindrical liquid storage tanks on the deformable soil is presented. Boundary elements and finite elements are combined to simulate the liquid-structure coupling effect while tuned foundation impedance functions (TFIF's) are representing the motion of the rigid foundation block on the flexible soil. Because the coupled dynamic system is expressed explicitly in terms of mass and stiffness, the developed scheme is applicable to any standard dynamic analysis methodologies. (author)

  5. Sensitivity analysis of an impedance void distribution in annular and bubbly flow: A theoretical study

    International Nuclear Information System (INIS)

    Lemonnier, H.; Nakach, R.; Favreau, C.; Selmer-Olsen, S.

    1989-01-01

    Impedance void meters are frequently used to measure area-averaged void fraction in pipes. This is primarily due to two reasons: first, this method is non-intrusive since the measurement can be done from electrodes flush mounted in the walls, and second, the signal processing equipment is simple. Impedance probes may be calibrated by using a pressure drop measurement or quick closing valves system and low attention is generally paid to void distribution effects. It can be proved that in annular flow, the departure from radial symmetry has a strong influence on the measured mean film thickness. This can be easily demonstrated by solving the Laplace equation for the electrical potential by simple analytical methods. When some spatial symmetry conditions are encountered, it is possible to calculate directly the conductance of the two-phase medium without calculating completely the potential. A solution of this problem by using the separation of variable technique is also presented. There, the main difficulty is due to the mixity of the boundary conditions: the boundary condition is both Neumann and Dirichlet type on the same coordinate curve. This formulation leads to a non-separable problem which is solved by truncating an infinite algebraic set of linear equations. (orig.)

  6. Measurement of transient two-phase flow velocity using statistical signal analysis of impedance probe signals

    International Nuclear Information System (INIS)

    Leavell, W.H.; Mullens, J.A.

    1981-01-01

    A computational algorithm has been developed to measure transient, phase-interface velocity in two-phase, steam-water systems. The algorithm will be used to measure the transient velocity of steam-water mixture during simulated PWR reflood experiments. By utilizing signals produced by two, spatially separated impedance probes immersed in a two-phase mixture, the algorithm computes the average transit time of mixture fluctuations moving between the two probes. This transit time is computed by first, measuring the phase shift between the two probe signals after transformation to the frequency domain and then computing the phase shift slope by a weighted least-squares fitting technique. Our algorithm, which has been tested with both simulated and real data, is able to accurately track velocity transients as fast as 4 m/s/s

  7. Fatigue properties and impedance analysis of potassium sodium niobate-strontium titanate transparent ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhiyong; Fan, Huiqing; Lei, Shenhui; Wang, Ju; Tian, Hailin [Northwestern Polytechnical University, State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Xi' an (China)

    2016-10-15

    Highly transparent ferroelectric ceramics based on 0.9K{sub 0.5}Na{sub 0.5}NbO{sub 3}-0.1SrTiO{sub 3} were prepared using a pressure-less solid-state sintering method without using hot isostatic pressing and spark plasma sintering. An independence electromechanical response of bipolar switching cycles (S{sub 33} only degraded 3.2 % up to 10{sup 7} cycles) was presented in this transparent ceramics, which indicated an extremely stable property under electric field. From impedance spectroscopy and X-ray photoelectron spectroscopy analyses, it was concluded that such optical transparency and fatigue-resistant behaviors were mainly attributed to the lower density of oxygen vacancies in the ceramics. (orig.)

  8. Analysis of mobile ionic impurities in polyvinylalcohol thin films by thermal discharge current and dielectric impedance spectroscopy

    Directory of Open Access Journals (Sweden)

    M. Egginger

    2012-12-01

    Full Text Available Polyvinylalcohol (PVA is a water soluble polymer frequently applied in the field of organic electronics for insulating thin film layers. By-products of PVA synthesis are sodium acetate ions which contaminate the polymer material and can impinge on the electronic performance when applied as interlayer dielectrics in thin film transistors. Uncontrollable voltage instabilities and unwanted hysteresis effects are regularly reported with PVA devices. An understanding of these effects require knowledge about the electronic dynamics of the ionic impurities and their influence on the dielectric properties of PVA. Respective data, which are largely unknown, are being presented in this work. Experimental investigations were performed from room temperature to 125°C on drop-cast PVA films of three different quality grades. Data from thermal discharge current (TDC measurements, polarization experiments, and dielectric impedance spectroscopy concurrently show evidence of mobile ionic carriers. Results from TDC measurements indicate the existence of an intrinsic, build-in electric field of pristine PVA films. The field is caused by asymmetric ionic double layer formation at the two different film-interfaces (substrate/PVA and PVA/air. The mobile ions cause strong electrode polarization effects which dominate dielectric impedance spectra. From a quantitative electrode polarization analysis of isothermal impedance spectra temperature dependent values for the concentration, the mobility and conductivity together with characteristic relaxation times of the mobile carriers are given. Also shown are temperature dependent results for the dc-permittivity and the electronic resistivity. The obtained results demonstrate the feasibility to partly remove contaminants from a PVA solution by dialysis cleaning. Such a cleaning procedure reduces the values of ion concentration, conductivity and relaxation frequency.

  9. Impedance spectroscopic and dielectric analysis of Ba0.7Sr0.3TiO3 thin films

    International Nuclear Information System (INIS)

    Rouahi, A.; Kahouli, A.; Sylvestre, A.; Defaÿ, E.; Yangui, B.

    2012-01-01

    Highlights: ► The material exhibits the contribution of both grain and grain boundaries in the electric response of Ba 0.7 Sr 0.3 TiO 3 . ► The plot of normalized complex dielectric modulus and impedance as a function of frequency exhibits both short and long-range conduction in the film. ► The frequency dependence of ac conductivity exhibits a polaron hopping mechanism with activation energy of 0.38 eV. ► The complex dielectric modulus analysis confirmed the presence of a non-Debye type of conductivity relaxation deduced from the KWW function. - Abstract: Polycrystalline Ba 0.7 Sr 0.3 TiO 3 thin film with Pt/BST/Pt/TiO 2 /SiO 2 structure was prepared by ion beam sputtering. The film was post annealed at 700 °C. The dielectric and electric modulus properties were studied by impedance spectroscopy over a wide frequency range [0.1–10 5 Hz] at different temperatures [175–350 °C]. The Nyquist plots (Z″ vs . Z′) show the contribution of both grain and grain boundaries at higher temperature on the electric response of BST thin films. Moreover, the resistance of grains decreases with the rise in temperature and the material exhibits a negative temperature coefficient of resistance. The electric modulus plot indicates the non-Debye type of dielectric relaxation. The values of the activation energy computed from both plots of Z″ and M″ are 0.86 eV and 0.81 eV respectively, which reveals that the species responsible for conduction are the same. The scaling behavior of M ″ /M ″ max shows the temperature independent nature of relaxation time. The plot of normalized complex dielectric modulus and impedance as a function of frequency exhibits both short and long-range conduction in the film.

  10. Analysis of Different Series-Parallel Connection Modules for Dye-Sensitized Solar Cell by Electrochemical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Jung-Chuan Chou

    2016-01-01

    Full Text Available The internal impedances of different dye-sensitized solar cell (DSSC models were analyzed by electrochemical impedance spectrometer (EIS with an equivalent circuit model. The Nyquist plot was built to simulate the redox reaction of internal device at the heterojunction. It was useful to analyze the component structure and promote photovoltaic conversion efficiency of DSSC. The impedance of DSSC was investigated and the externally connected module assembly was constructed utilizing single cells on the scaled-up module. According to the experiment results, the impedance was increased with increasing cells connected in series. On the contrary, the impedance was decreased with increasing cells connected in parallel.

  11. Species of lichenized and allied fungi new to Białowieża Large Forest (NE Poland

    Directory of Open Access Journals (Sweden)

    Krystyna Czyżewska

    2014-08-01

    Full Text Available The paper presents 38 species of lichenized and allied fungi new to Białowieża Large Forest. 24 taxa of lichenized Ascomycota and 14 taxa of lichenicolous and saprobic fungi are the result of the analysis of collected materials as well as additional field studies.

  12. Role of turbulent flow seawater in the corrosion enhancement of an Al–Zn–Mg alloy: an electrochemical impedance spectroscopy (EIS analysis of oxygen reduction reaction (ORR

    Directory of Open Access Journals (Sweden)

    Marcela C. Quevedo

    2018-04-01

    Full Text Available The effect of flow on the corrosion of Al–14 wt% Zn–8 wt% Mg alloy in aerated synthetic seawater at ambient temperature was studied using a rotating cylinder electrode (RCE under turbulent regime conditions by means of electrochemical impedance spectroscopy (EIS. The overall electrochemical corrosion process was found to be strongly influenced by the oxygen mass transfer process under turbulent flow conditions on the cathodic kinetics, driving to a significant increase in corrosion rate.At corrosion potential, Ecorr value, contributions from the anodic and cathodic processes involved were observed in the impedance diagrams. Instead, at a cathodic potential of −1.2 V (sce, impedance measurements proved the predominance of the mass-transfer process for oxygen. A primary analysis of the impedance plots allowed to confirm such situation. Keywords: Aluminum alloy, Corrosion, EIS, Flow, Oxygen, Mass transfer, Rotating cylinder electrode, Seawater

  13. Impedance-based analysis and study of phase sensitivity in slow-wave two-beam accelerators

    International Nuclear Information System (INIS)

    Wurtele, J.S.; Whittum, D.H.; Sessler, A.M.

    1992-06-01

    This paper presents a new formalism which makes the analysis and understanding of both the relativistic klystron (RK) and the standing-wave free-electron laser (SWFEL) two-beam accelerator (TBA) available to a wide audience of accelerator physicists. A ''coupling impedance'' for both the RK and SWFEWL is introduced, which can include realistic cavity features, such as beam and vacuum ports, in a simple manner. The RK and SWFEL macroparticle equations, which govern the energy and phase evolution of successive bunches in the beam, are of identical form, differing only by multiplicative factors. Expressions are derived for the phase and amplitude sensitivities of the TBA schemes to errors (shot-to-shot jitter) in current and energy. The analysis allows, for the first time, relative comparisons of the RK and the SWFEL TBAs

  14. Assessment of body fat proportion by means of bioelectrical impedance in athletic boys aged 7 to 18 years with respect to specific types of instruments

    Directory of Open Access Journals (Sweden)

    Sigmund Martin

    2015-07-01

    Full Text Available BACKGROUND: Bioelectrical impedance (BIA seems an appropriate method for basic diagnostics of body composition in a practical environment. This is a non-time consuming non-invasive method that provides a high degree of response relevance. However, the values identifi ed by the BIA method are susceptible to a number of factors, which need to be taken into account during the investigation stage and interpretation of the results. One of the signifi cant factors infl uencing the outcomes of measurement is the instrument factor.OBJECTIVE: The objective of the present comparative survey was to analyse the proportions of body fat by means of the BIA hand-to-leg method and BIA leg-to-leg method in a sample of athletic individuals aged 7 to 18 years.METHODS: The survey included a total of 178 ice-hockey players aged 7 to 18 years. The proportion of body fat analysed by means of the BIA hand-to-leg method was measured by the Tanita BC-418 MA instrument. For the purposes of the BIA leg-to-leg method the Tanita BF-350 instrument was used (Tanita, Japan. Both instruments work at a frequency of 50 kHz.RESULTS: The percentage of body fat established by the BIA leg-to-leg method (M = 13.5%; SD = 4.8 indicated signifi cantly lower values of fat percentage than the values measured by the BIA hand-to-leg method (M = 17.1%; SD = 4.3. The overall diff erence represents an average value of 3.6% (standard mode; p < .001; d = 0.8. Regarding the monitored age categories the observed diff erences are in the range of 3.1–4.7% (p < .001; d = 0.7–1.2.CONCLUSION: The present study compares the proportions of body fat by means of the BIA leg-to-leg method and BIA hand-to-leg method in athletic boys aged 7 to 18 years. The results measured by the BIA leg-to-leg method signifi cantly undervalue the proportion of body fat in comparison with the BIA hand-to-leg method. The instrument factor and age factor represented signifi - cant variables infl uencing the results of the

  15. New Application of Bioelectrical Impedance Analysis by the Back Propagation Artificial Neural Network Mathematically Predictive Model of Tissue Composition in the Lower Limbs of Elderly People

    Directory of Open Access Journals (Sweden)

    Tsang-Pai Liu

    2012-03-01

    Conclusion: In summary, the greater predictive accuracy and precision made the application of BIA with the BP–ANN mathematical model more feasible for the clinical measurement of FM and FFM in the lower limbs of elderly people.

  16. In-situ analysis of microwave conductivity and impedance spectroscopy for evaluation of charge carrier dynamics at interfaces

    Science.gov (United States)

    Choi, Wookjin; Inoue, Junichi; Tsutsui, Yusuke; Sakurai, Tsuneaki; Seki, Shu

    2017-11-01

    A unique concerted analysis comprising non-contact microwave conductivity measurements and impedance spectroscopy was developed to simultaneously assess the charge carrier mobility and injection barriers. The frequency dependence of the microwave conductivity as well as the electrical current was analyzed by applying sinusoidal voltage to determine the equivalent circuit parameters. Based on the temperature dependence of the circuit parameters, the energy of the injection barrier was estimated to be 0.4 eV with the Richardson-Schottky model, and the band-like transport was confirmed with the negative temperature coefficient with the β value of 1.4 in the intra-layer conduction of C8-BTBT. In contrast, the increase in the resistance of the C8-BTBT layer with decreasing temperature implied the occurrence of hopping-like transport in the inter-layer conduction of C8-BTBT.

  17. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...... and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key...... features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding...

  18. Impedance source power electronic converters

    CERN Document Server

    Liu, Yushan; Ge, Baoming; Blaabjerg, Frede; Ellabban, Omar; Loh, Poh Chiang

    2016-01-01

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding control methods. Presents the latest power conversion solutions that aim to advance the role of pow...

  19. Alternating current impedance spectroscopic analysis of biofunctionalized vertically-aligned silica nanospring surface for biosensor applications

    Science.gov (United States)

    Timalsina, Yukta P.

    In this dissertation, a process of vertically-aligned (silica) nanosprings (VANS) based biosensor development is presented. Alternating current (AC) impedance spectroscopy has been used to analyze sensor response as a function of saline phosphate (SP) buffer and biological solutions. The sensor is a parallel plate capacitor consisting of two glass substrates coated with indium tin oxide (ITO), where the VANS [or randomly-aligned nanosprings (RANS)] grown on one substrate serve as the dielectric spacer layer. The response of a VANS device as a function of ionic concentration in SP buffer was examined and an equivalent circuit model was developed. The results demonstrated that VANS sensors exhibited greater sensitivity to the changes in SP concentration relative to the ITO sensors, which serve as controls. The biofunctionalized VANS surface via physisorption and the cross-linker method demonstrates the repeatability, specificity, and selectivity of the binding. The physisorption of biotinylated immunoglobulin G (B-IgG) onto the VANS surface simplifies the whole sensing procedure for the detection of glucose oxidase, since the avidin-conjugated glucose oxidase (Av-GOx) can directly be immobilized on the B-IgG. The cross linker method involves the covalent attachment of antibodies onto the functionalized VANS surface via imine bond. The experiments revealed that the VANS sensor response is solely the result of the interaction of target molecule i.e. mouse IgG with the probe layer, i.e. goat antimouse IgG (GalphaM IgG). It was determined that VANS-based sensors exhibit a greater magnitude of change between successive bio-layers relative to the controls above 100 Hz, which indicates that the addition of biomolecules inhibits the diffusion of ions and changes the effective dielectric response of the VANS via biomolecular polarization. The study of ionic transport in nanosprings suggested that conductance follows a scaling law. It was demonstrated that a VANS-based device

  20. Electromagnetic Scattering Analysis of Coated Conductors With Edges Using the Method of Auxiliary Sources (MAS) in Conjunction With the Standard Impedance Boundary Condition (SIBC)

    DEFF Research Database (Denmark)

    Anastassiu, H.T.; D.I.Kaklamani, H.T.; Economou, D.P.

    2002-01-01

    A novel combination of the method of auxiliary sources (MAS) and the standard impedance boundary condition (SIBC) is employed in the analysis of transverse magnetic (TM) plane wave scattering from infinite, coated, perfectly conducting cylinders with square cross sections. The scatterer is initia......A novel combination of the method of auxiliary sources (MAS) and the standard impedance boundary condition (SIBC) is employed in the analysis of transverse magnetic (TM) plane wave scattering from infinite, coated, perfectly conducting cylinders with square cross sections. The scatterer...

  1. The use of bioelectrical impedance analysis to estimate total body water in young children with cerebral palsy.

    Science.gov (United States)

    Bell, Kristie L; Boyd, Roslyn N; Walker, Jacqueline L; Stevenson, Richard D; Davies, Peter S W

    2013-08-01

    Body composition assessment is an essential component of nutritional evaluation in children with cerebral palsy. This study aimed to validate bioelectrical impedance to estimate total body water in young children with cerebral palsy and determine best electrode placement in unilateral impairment. 55 young children with cerebral palsy across all functional ability levels were included. Height/length was measured or estimated from knee height. Total body water was estimated using a Bodystat 1500MDD and three equations, and measured using the gold standard, deuterium dilution technique. Comparisons were made using Bland Altman analysis. For children with bilateral impairment, the Fjeld equation estimated total body water with the least bias (limits of agreement): 0.0 L (-1.4 L to 1.5 L); the Pencharz equation produced the greatest: 2.7 L (0.6 L-4.8 L). For children with unilateral impairment, differences between measured and estimated total body water were lowest on the unimpaired side using the Fjeld equation 0.1 L (-1.5 L to 1.6 L)) and greatest for the Pencharz equation. The ability of bioelectrical impedance to estimate total body water depends on the equation chosen. The Fjeld equation was the most accurate for the group, however, individual results varied by up to 18%. A population specific equation was developed and may enhance the accuracy of estimates. Australian New Zealand Clinical Trials Registry (ANZCTR) number: ACTRN12611000616976. Copyright © 2012 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  2. 23 CFR 661.55 - How are BIA and Tribal owned IRR bridges inspected?

    Science.gov (United States)

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false How are BIA and Tribal owned IRR bridges inspected? 661... AND TRAFFIC OPERATIONS INDIAN RESERVATION ROAD BRIDGE PROGRAM § 661.55 How are BIA and Tribal owned IRR bridges inspected? BIA and Tribally owned IRR bridges are inspected in accordance with 25 CFR part...

  3. 25 CFR 170.2 - What is the IRR Program and BIA Road Maintenance Program policy?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false What is the IRR Program and BIA Road Maintenance Program... and BIA Road Maintenance Program policy? (a) It is the policy of the Secretary of the Interior and the... designed to enable Indian tribes to participate in all contractible IRR and BIA Road Maintenance programs...

  4. The added value of quantitative analysis of on-therapy impedance-pH parameters in distinguishing refractory non-erosive reflux disease from functional heartburn.

    Science.gov (United States)

    Frazzoni, M; Conigliaro, R; Mirante, V G; Melotti, G

    2012-02-01

    By analysis of symptom-reflux association, endoscopy-negative refractory heartburn can be related to acid/non-acid refluxes with impedance-pH monitoring. Unfortunately, patients frequently do not report symptoms during the test. We aimed to assess the contribution of quantitative analysis of impedance-pH parameters added to symptom-reflux association in evaluating patients with endoscopy-negative heartburn refractory to high-dose proton pump inhibitor therapy. The symptom association probability (SAP), the symptom index (SI), the esophageal acid exposure time and the number of distal and proximal refluxes were assessed at on-therapy impedance-pH monitoring. Relationships with hiatal hernia and manometric findings were also evaluated. Eighty patients were prospectively studied. Refractory heartburn was more frequently related to reflux by a positive SAP/SI and/or abnormal impedance-pH parameters (52/80 cases) (65%) than by a positive SAP/SI only (38/80 cases) (47%) (P = 0.038). In patients with refractory non-erosive reflux disease (NERD) defined by a positive SAP/SI and/or abnormal impedance-pH parameters, the prevalence of hiatal hernia was significantly higher (56%vs 21%, P = 0.007) and the mean lower esophageal sphincter tone was significantly lower (18.7 vs 25.8 mmHg, P = 0.005) than in those (35%) with reflux-unrelated, i.e., functional heartburn (FH). On the contrary, no significant difference was observed subdividing patients according to a positive SAP/SI only. Quantitative analysis of impedance-pH parameters added to symptom-reflux association allows a subdivision of refractory-heartburn patients into refractory NERD and FH which is substantiated by pathophysiological findings and which restricts the diagnosis of FH to one third of cases. © 2011 Blackwell Publishing Ltd.

  5. Electrochemical impedance spectroscopy analysis with a symmetric cell for LiCoO2 cathode degradation correlated with Co dissolution

    Directory of Open Access Journals (Sweden)

    Hiroki Nara

    2016-04-01

    Full Text Available Static degradation of LiCoO2 cathodes is a problem that hinders accurate analysis using our developed separable symmetric cell. Therefore, in this study we investigate the static degradation of LiCoO2 cathodes in separable symmetric cells by electrochemical impedance spectroscopy (EIS and inductively coupled plasma analyses. EIS measurements of LiCoO2 cathodes are conducted in various electrolytes, with different anions and with or without HF and/or H2O. This allows us to determine the static degradation of LiCoO2 cathodes relative to their increase of charge transfer resistance. The increase of the charge transfer resistance of the LiCoO2 cathodes is attributed to cobalt dissolution from the active material of LiCoO2. Cobalt dissolution from LiCoO2 is revealed to occur even at low potential in the presence of HF, which is generated from LiPF6 and H2O. The results indicate that avoidance of HF generation is important for the analysis of lithium-ion battery electrodes by using the separable cell. These findings reveal the condition to achieve accurate analysis by EIS using the separable cell.

  6. Relationship between Height-Weight Difference Index and Body-Fat Percentage Estimated by Bioelectrical Impedance Analysis in Thai Adults

    Directory of Open Access Journals (Sweden)

    Kanokkarn Juntaping

    2017-01-01

    Full Text Available Introduction. The height-weight difference index (HWDI is a new indicator for evaluating obesity status. While body-fat percentage (BF% is considered to be the most accurate obesity evaluation tool, it is a more expensive method and more difficult to measure than the others. Objective. Our objectives were to find the relationship between HWDI and BF% and to find a BF% prediction model from HWDI in relation to age and gender. Method. Bioelectrical impedance analysis was used to measure BF% in 2,771 healthy adult Thais. HWDI was calculated as the difference between height and weight. Pearson’s correlation coefficient was used to assess the relationship between HWDI and BF%. Multiple linear and nonlinear regression analysis were used to construct the BF% prediction model. Results. HWDI and BF% were found to be inverse which related to a tendency toward a linear relationship. Results of a multivariate linear regression analysis, which included HWDI and age as variables in the model, predicted BF% to be 34.508 − 0.159 (HWDI + 0.161 (age for men and 53.35 − 0.265 (HWDI + 0.132 (age for women. Conclusions. The prediction model provides an easy-to-use obesity evaluation tool that should help awareness of underweight and obesity conditions.

  7. Photoanode Thickness Optimization and Impedance Spectroscopic Analysis of Dye-Sensitized Solar Cells based on a Carbazole-Containing Ruthenium Dye

    Science.gov (United States)

    Choi, Jongwan; Kim, Felix Sunjoo

    2018-03-01

    We studied the influence of photoanode thickness on the photovoltaic characteristics and impedance responses of the dye-sensitized solar cells based on a ruthenium dye containing a hexyloxyl-substituted carbazole unit (Ru-HCz). As the thickness of photoanode increases from 4.2 μm to 14.8 μm, the dye-loading amount and the efficiency increase. The device with thicker photoanode shows a decrease in the efficiency due to the higher probability of recombination of electron-hole pairs before charge extraction. We also analyzed the electron-transfer and recombination characteristics as a function of photoanode thickness through detailed electrochemical impedance spectroscopy analysis.

  8. Advances In Impedance Theory

    International Nuclear Information System (INIS)

    Stupakov, G.

    2009-01-01

    We review recent progress in the following areas of the impedance theory: calculation of impedance of tapers and small angle collimators; optical approximation and parabolic equation for the high-frequency impedance; impedance due to resistive inserts in a perfectly conducting pipe.

  9. Body fat measurement by bioelectrical impedance and air displacement plethysmography: a cross-validation study to design bioelectrical impedance equations in Mexican adults

    Directory of Open Access Journals (Sweden)

    Valencia Mauro E

    2007-08-01

    Full Text Available Abstract Background The study of body composition in specific populations by techniques such as bio-impedance analysis (BIA requires validation based on standard reference methods. The aim of this study was to develop and cross-validate a predictive equation for bioelectrical impedance using air displacement plethysmography (ADP as standard method to measure body composition in Mexican adult men and women. Methods This study included 155 male and female subjects from northern Mexico, 20–50 years of age, from low, middle, and upper income levels. Body composition was measured by ADP. Body weight (BW, kg and height (Ht, cm were obtained by standard anthropometric techniques. Resistance, R (ohms and reactance, Xc (ohms were also measured. A random-split method was used to obtain two samples: one was used to derive the equation by the "all possible regressions" procedure and was cross-validated in the other sample to test predicted versus measured values of fat-free mass (FFM. Results and Discussion The final model was: FFM (kg = 0.7374 * (Ht2 /R + 0.1763 * (BW - 0.1773 * (Age + 0.1198 * (Xc - 2.4658. R2 was 0.97; the square root of the mean square error (SRMSE was 1.99 kg, and the pure error (PE was 2.96. There was no difference between FFM predicted by the new equation (48.57 ± 10.9 kg and that measured by ADP (48.43 ± 11.3 kg. The new equation did not differ from the line of identity, had a high R2 and a low SRMSE, and showed no significant bias (0.87 ± 2.84 kg. Conclusion The new bioelectrical impedance equation based on the two-compartment model (2C was accurate, precise, and free of bias. This equation can be used to assess body composition and nutritional status in populations similar in anthropometric and physical characteristics to this sample.

  10. Prediction of fat-free body mass from bioelectrical impedance and anthropometry among 3-year-old children using DXA

    DEFF Research Database (Denmark)

    Ejlerskov, Katrine Tschentscher; Jensen, Signe Marie; Christensen, Line B

    2014-01-01

    For 3-year-old children suitable methods to estimate body composition are sparse. We aimed to develop predictive equations for estimating fat-free mass (FFM) from bioelectrical impedance (BIA) and anthropometry using dual-energy X-ray absorptiometry (DXA) as reference method using data from 99......-validation approach. Prediction error of FFM was 3.0% for both equations (root mean square error: 360 and 356 g, respectively). The derived equations produced BIA-based prediction of FFM and FM near DXA scan results. We suggest that the predictive equations can be applied in similar population samples aged 2-4 years...

  11. Noise and ac impedance analysis of ion transfer kinetics at the micro liquid/liquid interface

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Oksana; Holub, Karel; Mareček, Vladimír

    2015-01-01

    Roč. 56, JUL 2015 (2015), s. 43-45 ISSN 1388-2481 R&D Projects: GA ČR GA13-04630S Institutional support: RVO:61388955 Keywords : noise analysis * liquid/liquid interface * ion transfer kinetics Subject RIV: CG - Electrochemistry Impact factor: 4.569, year: 2015

  12. FEM Analysis of Beam-coupling Impedance and RF Contacts Criticality on the LHC UA9 Piezo Goniometer

    CERN Document Server

    Danisi, A; Passarelli, A; Masi, A; Losito, R; Salvant, B

    2014-01-01

    The UA9 piezo-goniometer has been designed to guarantee micro-radians-accuracy angular positioning of a silicon crystal for a crystal collimation experiment in the LHC, and to minimize the impact on the LHC beam coupling impedance. This paper presents a Finite Element Method (FEM) study of the device, in both parking and operational positions, to evaluate its impact on the LHC impedance budget. In addition, the shielding contribution of the RF gaskets has been carefully evaluated, with the objective to assess the consequences for operation in case of their failure. A final word is drawn on the overall device impedance criticality.

  13. Analysis of low-dimensional radio-frequency impedance-based cardio-synchronous waveforms for biometric authentication.

    Science.gov (United States)

    Venugopalan, Shreyas; Savvides, Marios; Griofa, Marc O; Cohen, Ken

    2014-08-01

    Over the past two decades, there have been a lot of advances in the field of pattern analyses for biomedical signals, which have helped in both medical diagnoses and in furthering our understanding of the human body. A relatively recent area of interest is the utility of biomedical signals in the field of biometrics, i.e., for user identification. Seminal work in this domain has already been done using electrocardiograph (ECG) signals. In this paper, we discuss our ongoing work in using a relatively recent modality of biomedical signals-a cardio-synchronous waveform measured using a Radio-Frequency Impedance-Interrogation (RFII) device for the purpose of user identification. Compared to an ECG setup, this device is noninvasive and measurements can be obtained easily and quickly. Here, we discuss the feasibility of reducing the dimensions of these signals by projecting onto various subspaces while still preserving interuser discriminating information. We compare the classification performance using classical dimensionality reduction methods such as principal component analysis (PCA), independent component analysis (ICA), random projections, with more recent techniques such as K-SVD-based dictionary learning. We also report the reconstruction accuracies in these subspaces. Our results show that the dimensionality of the measured signals can be reduced by 60 fold while maintaining high user identification rates.

  14. Association of phase angle on bioelectrical impedance analysis and dialysis frequency with survival of chronic hemodialysis patients

    Science.gov (United States)

    Muzasti, R. A.; Lubis, H. R.

    2018-03-01

    Phase angle, a parameter by Bioelectrical Impedance Analysis, can detect body composition changes, so it can be used as a prognostic indicator in some chronic conditions. This study was for determining the relationship between PhA and hemodiálisis frequency with the survival of chronic hemodiálisis patients. This longitudinal retrospective study involved 173 chronic hemodiálisis patients at Rasyida Renal Hospital. The Kaplan-Meier method is used to determine the survival. Cox proportional hazard analysis is used to determine which variables significantly increase mortality. During the study period, 89 patients underwent hemodiálysis 3x a week (4 hours/session), and 84 patients underwent HD 2x a week (5 hours/session). Demographic and clinical characteristics in both groups were similar. There was no difference in PhA value in groups of 3x a week and group 2x a week (4.02 ± 1.13 vs 4.25 ± 1.12). Patients with twice a week hemodiálisis had a shorter survival than the 3x week group (35.14 ± 2.76 vs 38.62 ± 3.03) although it was not statistically significant (p = 0.126).

  15. Comparison of body fat using various bioelectrical impedance analyzers in university students

    Directory of Open Access Journals (Sweden)

    Petr Kutáč

    2015-12-01

    Full Text Available Background: At present, the portfolio of devices using the bioelectrical impedance (BIA method is continuously expanding as a result of the wide use of this method in the field as measurements by this method are fast and staff training is simple and reasonably priced. Nonetheless, the problem is that despite using the same method, bioimpedance analyzers can differ in many parameters. They use different electric current frequencies, a different number of electrodes and the electric current may be conducted through different parts of the body.Objective: The main objective of the study is to compare and evaluate the differences of values of the analysis of the body fat of university students measured by BIA analyzers that differ in the applied electric current frequency, number of electrodes and flow of the electric current through the individual body parts.Methods: The research included 125 participants (70 male and 55 female. The measurements were taken by the following analyzers: Tanita 418 MA, InBody 720, InBody R20 and Omron BF 300.Results: The differences in the mean values of the body fat representation between the used analyzers in men ranged from 0.1 to 3.4% and from 0.0 to 2.4 kg, in women from 0.5 to 6.5% and from 0.4 to 3.8 kg in relation to the used analyzer.Conclusions: In men with regular physical activity, the values measured by InBody R20 were statistically and practically different. The analyzer measured higher values that other analyzers. In women, there were statistically and practically significant differences in the values measured by Omron BF 300. This analyzer measured lower values than other analyzers.

  16. Bioelectrical impedance phase angle in clinical practice: implications for prognosis in stage IIIB and IV non-small cell lung cancer

    Directory of Open Access Journals (Sweden)

    Grutsch James F

    2009-01-01

    Full Text Available Abstract Background A frequent manifestation of advanced lung cancer is malnutrition, timely identification and treatment of which can lead to improved patient outcomes. Bioelectrical impedance analysis (BIA is an easy-to-use and non-invasive technique to evaluate changes in body composition and nutritional status. We investigated the prognostic role of BIA-derived phase angle in advanced non-small cell lung cancer (NSCLC. Methods A case series of 165 stages IIIB and IV NSCLC patients treated at our center. The Kaplan Meier method was used to calculate survival. Cox proportional hazard models were constructed to evaluate the prognostic effect of phase angle, independent of stage at diagnosis and prior treatment history. Results 93 were males and 72 females. 61 had stage IIIB disease at diagnosis while 104 had stage IV. The median phase angle was 5.3 degrees (range = 2.9 – 8. Patients with phase angle 5.3 had 12.4 months (95% CI: 10.5 to 18.7; n = 84; (p = 0.02. After adjusting for age, stage at diagnosis and prior treatment history we found that every one degree increase in phase angle was associated with a relative risk of 0.79 (95% CI: 0.64 to 0.97, P = 0.02. Conclusion We found BIA-derived phase angle to be an independent prognostic indicator in patients with stage IIIB and IV NSCLC. Nutritional interventions targeted at improving phase angle could potentially lead to an improved survival in patients with advanced NSCLC.

  17. 25 CFR 170.808 - Can BIA Road Maintenance Program funds be used to improve IRR transportation facilities?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Can BIA Road Maintenance Program funds be used to improve... THE INTERIOR LAND AND WATER INDIAN RESERVATION ROADS PROGRAM BIA Road Maintenance § 170.808 Can BIA Road Maintenance Program funds be used to improve IRR transportation facilities? No. BIA Road...

  18. Power Flow Analysis for Low-Voltage AC and DC Microgrids Considering Droop Control and Virtual Impedance

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay Kumar; Savaghebi, Mehdi

    2017-01-01

    In the low-voltage (LV) ac microgrids (MGs), with a relatively high R/X ratio, virtual impedance is usually adopted to improve the performance of droop control applied to distributed generators (DGs). At the same time, LV dc MG using virtual impedance as droop control is emerging without adequate...... power flow studies. In this paper, power flow analyses for both ac and dc MGs are formulated and implemented. The mathematical models for both types of MGs considering the concept of virtual impedance are used to be in conformity with the practical control of the DGs. As a result, calculation accuracy...... is improved for both ac and dc MG power flow analyses, comparing with previous methods without considering virtual impedance. Case studies are conducted to verify the proposed power flow analyses in terms of convergence and accuracy. Investigation of the impact to the system of internal control parameters...

  19. Bioelectrical impedance and visceral fat: a comparison with computed tomography in adults and elderly

    International Nuclear Information System (INIS)

    Eickemberg, Michaela; Roriz, Anna Karla Carneiro; Fontes, Gardenia Abreu Vieira; Sampaio, Lilian Ramos

    2013-01-01

    Objective: To evaluate the association between electrical bioimpedance analysis (BIA) and visceral fat (VF) in adult and elderly patients. Subjects and methods: This was a cross-sectional study, with a sample of 191 subjects (52% women, 49% elderly) stratified by sex, age and body mass. Computerized tomography (VF area) and BIA (percentage of total body fat (%TBF-BIA), phase angle, reactance and resistance) data were generated. Statistical analysis was based on Pearson's Correlation Coefficient, Anova, Pearson's Chi-square, and ROC curves. Results: VF areas ≥ 130 cm 2 were more prevalent among the elderly and among men. Adult females showed a stronger correlation between GV and %TBF-BIA. The other groups showed similar results and statistically significant correlations. Correlations between GV and phase angle were weak and not statistically significant. ROC Curves analyzes showed the following %TBF-BIA, which identified excess VF: for male subjects: 21.5% (adults) and 24.25% (elderly); for female subjects: 35.05% (adults) and 38.45% (elderly) with sensitivity of 78.6%, 82.1%, 83.3%, and 66.7%, and specificity of 70.6%, 62.5%, 79.1%, and 69%, respectively. Conclusion: BIA was found to have satisfactory sensitivity and specificity to predict VF; however, other devices and other techniques should be investigated to improve VF prediction. (author)

  20. Impedance Based Analysis of DFIG Stator Current Unbalance and Distortion Suppression Strategies

    DEFF Research Database (Denmark)

    Song, Yipeng; Zhou, Dao; Blaabjerg, Frede

    2016-01-01

    The control strategies of Doubly Fed Induction Generator (DFIG) system output current unbalance and distortion suppression have been well investigated in detail, with the implementation of two kinds of resonant regulators, i.e., conventional Resonance (R) regulator or Vector Proportional Integral...... reshaping though the introduction of R and VPI regulator. It is pointed out that, when implemented in the DFIG system output current unbalance and distortion suppression, the VPI regulator (equivalent to the combination of virtual positive inductor and virtual positive resistor) has two advantages over R...... regulator (equivalent to the combination of virtual positive resistor and virtual negative inductor), i.e., better high order harmonic distortion suppression. The theoretical analysis and MATLAB simulation results have validated the correctness of this conclusion....

  1. Single Frequency Impedance Analysis on Reduced Graphene Oxide Screen-Printed Electrode for Biomolecular Detection.

    Science.gov (United States)

    Rajesh; Singal, Shobhita; Kotnala, Ravinder K

    2017-10-01

    A biofunctionalized reduced graphene oxide (rGO)-modified screen-printed carbon electrode (SPCE) was constructed as an immunosensor for C-reactive protein (CRP) detection, a biomarker released in early stage acute myocardial infarction. A different approach of single frequency analysis (SFA) study was utilized for the biomolecular sensing, by monitoring the response in phase angle changes obtained at an optimized frequency resulting from antigen-antibody interactions. A set of measurements were carried out to optimize a frequency where a maximum change in phase angle was observed, and in this case, we found it at around 10 Hz. The bioelectrode was characterized by contact angle measurements, scanning electron microscopy, and electrochemical techniques. A concentration-dependent response of immunosensor to CRP with the change in phase angle, at a fixed frequency of 10 Hz, was found to be in the range of 10 ng mL -1 to 10 μg mL -1 in PBS and was fit quantitative well with the Hill-Langmuir equation. Based on the concentration-response data, the dissociation constant (K d ) was found to be 3.5 nM (with a Hill coefficient n = 0.57), which indicated a negative cooperativity with high anti-CRP (antibody)-CRP (antigen) binding at the electrode surface. A low-frequency analysis of sensing with an ease of measurement on a disposable electroactive rGO-modified electrode with high selectivity and sensitivity makes it a potential tool for biological sensors.

  2. The potential of classic and specific bioelectrical impedance vector analysis for the assessment of sarcopenia and sarcopenic obesity

    Directory of Open Access Journals (Sweden)

    Marini E

    2012-12-01

    Full Text Available Elisabetta Marini,1 Roberto Buffa,1 Bruno Saragat,1 Alessandra Coin,2 Elena Debora Toffanello,2 Linda Berton,2 Enzo Manzato,2 Giuseppe Sergi21Department of Environmental and Life Sciences, University of Cagliari, Italy; 2Department of Medicine-DIMED, Geriatrics Section, University of Padua, ItalyPurpose: The aim of this paper is to investigate whether bioelectrical impedance vector analysis (BIVA can be a suitable technique for the assessment of sarcopenia. We also investigate the potential use of specific BIVA as an indicator of sarcopenic obesity.Subjects and methods: The sample comprised 207 free-living elderly individuals of both sexes, aged 65 to 93 years. Anthropometric and bioelectrical measurements were taken according to standard criteria. The “classic” and “specific” BIVA procedures, which respectively correct bioelectrical values for body height and body geometry, were used. Dual energy X-ray absorptiometry (DXA was used as the reference method for identifying sarcopenic and obese sarcopenic individuals. Bioelectrical and DXA values were compared using Student’s t-test and Hotelling’s T2 test, as well as Pearson’s correlation coefficient.Results: According to classic BIVA, sarcopenic individuals of both sexes showed higher values of resistance/height (R/H; p < 0.01 and impedance/height (Z/H; p < 0.01, and a lower phase angle (p < 0.01. Similarly, specific BIVA showed significant differences between sarcopenic and nonsarcopenic individuals (men: T2 = 15.7, p < 0.01; women: T2 = 10.7, p < 0.01, with the sarcopenic groups showing a lower specific reactance and phase angle. Phase angle was positively correlated with the skeletal muscle mass index (men: r = 0.52, p < 0.01; women: r = 0.31, p < 0.01. Specific BIVA also recognized bioelectrical differences between sarcopenic and sarcopenic obese men (T2 = 13.4, p < 0.01, mainly due to the higher values of specific R in sarcopenic obese individuals.Conclusion: BIVA detected

  3. Cold vacuum chamber for diagnostics: Analysis of the measurements at the Diamond Light Source and impedance bench measurements

    Science.gov (United States)

    Voutta, R.; Gerstl, S.; Casalbuoni, S.; Grau, A. W.; Holubek, T.; Saez de Jauregui, D.; Bartolini, R.; Cox, M. P.; Longhi, E. C.; Rehm, G.; Schouten, J. C.; Walker, R. P.; Migliorati, M.; Spataro, B.

    2016-05-01

    The beam heat load is an important input parameter needed for the cryogenic design of superconducting insertion devices. Theoretical models taking into account the different heating mechanisms of an electron beam to a cold bore predict smaller values than the ones measured with several superconducting insertion devices installed in different electron storage rings. In order to measure and possibly understand the beam heat load to a cold bore, a cold vacuum chamber for diagnostics (COLDDIAG) has been built. COLDDIAG is equipped with temperature sensors, pressure gauges, mass spectrometers as well as retarding field analyzers which allow to measure the beam heat load, total pressure, and gas content as well as the flux of particles hitting the chamber walls. COLDDIAG was installed in a straight section of the Diamond Light Source (DLS). In a previous paper the experimental equipment as well as the installation of COLDDIAG in the DLS are described [S. Gerstl et al., Phys. Rev. ST Accel. Beams 17, 103201 (2014)]. In this paper we present an overview of all the measurements performed with COLDDIAG at the DLS and their detailed analysis, as well as impedance bench measurements of the cold beam vacuum chamber performed at the Karlsruhe Institute of Technology after removal from the DLS. Relevant conclusions for the cryogenic design of superconducting insertion devices are drawn from the obtained results.

  4. Cold vacuum chamber for diagnostics: Analysis of the measurements at the Diamond Light Source and impedance bench measurements

    Directory of Open Access Journals (Sweden)

    R. Voutta

    2016-05-01

    Full Text Available The beam heat load is an important input parameter needed for the cryogenic design of superconducting insertion devices. Theoretical models taking into account the different heating mechanisms of an electron beam to a cold bore predict smaller values than the ones measured with several superconducting insertion devices installed in different electron storage rings. In order to measure and possibly understand the beam heat load to a cold bore, a cold vacuum chamber for diagnostics (COLDDIAG has been built. COLDDIAG is equipped with temperature sensors, pressure gauges, mass spectrometers as well as retarding field analyzers which allow to measure the beam heat load, total pressure, and gas content as well as the flux of particles hitting the chamber walls. COLDDIAG was installed in a straight section of the Diamond Light Source (DLS. In a previous paper the experimental equipment as well as the installation of COLDDIAG in the DLS are described [S. Gerstl et al., Phys. Rev. ST Accel. Beams 17, 103201 (2014]. In this paper we present an overview of all the measurements performed with COLDDIAG at the DLS and their detailed analysis, as well as impedance bench measurements of the cold beam vacuum chamber performed at the Karlsruhe Institute of Technology after removal from the DLS. Relevant conclusions for the cryogenic design of superconducting insertion devices are drawn from the obtained results.

  5. Variant allele frequency enrichment analysis in vitro reveals sonic hedgehog pathway to impede sustained temozolomide response in GBM.

    Science.gov (United States)

    Biswas, Nidhan K; Chandra, Vikas; Sarkar-Roy, Neeta; Das, Tapojyoti; Bhattacharya, Rabindra N; Tripathy, Laxmi N; Basu, Sunandan K; Kumar, Shantanu; Das, Subrata; Chatterjee, Ankita; Mukherjee, Ankur; Basu, Pryiadarshi; Maitra, Arindam; Chattopadhyay, Ansuman; Basu, Analabha; Dhara, Surajit

    2015-01-21

    Neoplastic cells of Glioblastoma multiforme (GBM) may or may not show sustained response to temozolomide (TMZ) chemotherapy. We hypothesize that TMZ chemotherapy response in GBM is predetermined in its neoplastic clones via a specific set of mutations that alter relevant pathways. We describe exome-wide enrichment of variant allele frequencies (VAFs) in neurospheres displaying contrasting phenotypes of sustained versus reversible TMZ-responses in vitro. Enrichment of VAFs was found on genes ST5, RP6KA1 and PRKDC in cells showing sustained TMZ-effect whereas on genes FREM2, AASDH and STK36, in cells showing reversible TMZ-effect. Ingenuity pathway analysis (IPA) revealed that these genes alter cell-cycle, G2/M-checkpoint-regulation and NHEJ pathways in sustained TMZ-effect cells whereas the lysine-II&V/phenylalanine degradation and sonic hedgehog (Hh) pathways in reversible TMZ-effect cells. Next, we validated the likely involvement of the Hh-pathway in TMZ-response on additional GBM neurospheres as well as on GBM patients, by extracting RNA-sequencing-based gene expression data from the TCGA-GBM database. Finally, we demonstrated TMZ-sensitization of a TMZ non-responder neurosphere in vitro by treating them with the FDA-approved pharmacological Hh-pathway inhibitor vismodegib. Altogether, our results indicate that the Hh-pathway impedes sustained TMZ-response in GBM and could be a potential therapeutic target to enhance TMZ-response in this malignancy.

  6. Malnutrition in remission of childhood cancers as assessed by bioelectric impedance analysis

    Directory of Open Access Journals (Sweden)

    M. V. Konovalova

    2014-07-01

    Full Text Available The results of our cross-sectional bioimpedance study of children aged 7–17 years cured of cancer during follow-up (patients’ group, n = 552, remission time range 0–15 years and of age-matched healthy controls (n = 1,500 show significant intergroup differences in body height and body composition parameters. The most pronounced alterations in the patients’ group were observed in standardized values of phase angle reflecting a sharp decrease in the percentage of metabolically active body cell mass in fat-free mass. Malnutrition, judged from the prevalence of obesity and low phase angle, was observed in 52.7 % of our patients reaching a maximum of 76.8 % in a subgroup of children with CNS tumors. In view of known association that exists between malnutrition and reduced tolerance to chemotherapy, increased susceptibility to infections and adverse outcomes rate, we recommend using bioimpedance analysis in remission of childhood cancers in order to monitoring and timely correction of nutritional state as well as for prevention of delayed cardiovascular risks.

  7. Malnutrition in remission of childhood cancers as assessed by bioelectric impedance analysis

    Directory of Open Access Journals (Sweden)

    M. V. Konovalova

    2012-01-01

    Full Text Available The results of our cross-sectional bioimpedance study of children aged 7–17 years cured of cancer during follow-up (patients’ group, n = 552, remission time range 0–15 years and of age-matched healthy controls (n = 1,500 show significant intergroup differences in body height and body composition parameters. The most pronounced alterations in the patients’ group were observed in standardized values of phase angle reflecting a sharp decrease in the percentage of metabolically active body cell mass in fat-free mass. Malnutrition, judged from the prevalence of obesity and low phase angle, was observed in 52.7 % of our patients reaching a maximum of 76.8 % in a subgroup of children with CNS tumors. In view of known association that exists between malnutrition and reduced tolerance to chemotherapy, increased susceptibility to infections and adverse outcomes rate, we recommend using bioimpedance analysis in remission of childhood cancers in order to monitoring and timely correction of nutritional state as well as for prevention of delayed cardiovascular risks.

  8. A comparison between handgrip strength, upper limb fat free mass by segmental bioelectrical impedance analysis (SBIA) and anthropometric measurements in young males

    International Nuclear Information System (INIS)

    Gonzalez-Correa, C H; Caicedo-Eraso, J C; Varon-Serna, D R

    2013-01-01

    The mechanical function and size of a muscle may be closely linked. Handgrip strength (HGS) has been used as a predictor of functional performing. Anthropometric measurements have been made to estimate arm muscle area (AMA) and physical muscle mass volume of upper limb (ULMMV). Electrical volume estimation is possible by segmental BIA measurements of fat free mass (SBIA-FFM), mainly muscle-mass. Relationship among these variables is not well established. We aimed to determine if physical and electrical muscle mass estimations relate to each other and to what extent HGS is to be related to its size measured by both methods in normal or overweight young males. Regression analysis was used to determine association between these variables. Subjects showed a decreased HGS (65.5%), FFM, (85.5%) and AMA (74.5%). It was found an acceptable association between SBIA-FFM and AMA (r 2 = 0.60) and poorer between physical and electrical volume (r 2 = 0.55). However, a paired Student t-test and Bland and Altman plot showed that physical and electrical models were not interchangeable (pt 2 = 0.07) and electrical (r 2 = 0.192) ULMMV showing that muscle mass quantity does not mean muscle strength. Other factors influencing HGS like physical training or nutrition require more research.

  9. The investigation of the some body parameters of obese and (obese+diabetes) patients with using bioelectrical impedance analysis techniques

    Science.gov (United States)

    Yerlikaya, Emrah; Karageçili, Hasan; Aydin, Ruken Zeynep

    2016-04-01

    Obesity is a key risk for the development of hyperglycemia, hypertension, hyperlipidemia, insulin resistance and is totally referred to as the metabolic disorders. Diabetes mellitus, a metabolic disorder, is related with hyperglycemia, altered metabolism of lipids, carbohydrates and proteins. The minimum defining characteristic feature to identify diabetes mellitus is chronic and substantiated elevation of circulating glucose concentration. In this study, it is aimed to determine the body composition analyze of obese and (obese+diabetes) patients.We studied the datas taken from three independent groups with the body composition analyzer instrument. The body composition analyzer calculates body parameters, such as body fat ratio, body fat mass, fat free mass, estimated muscle mass, and base metabolic rate on the basis of data obtained by Dual Energy X-ray Absorptiometry using Bioelectrical Impedance Analysis. All patients and healthy subjects applied to Siirt University Medico and their datas were taken. The Statistical Package for Social Sciences version 21 was used for descriptive data analysis. When we compared and analyzed three groups datas, we found statistically significant difference between obese, (obese+diabetes) and control groups values. Anova test and tukey test are used to analyze the difference between groups and to do multiple comparisons. T test is also used to analyze the difference between genders. We observed the statistically significant difference in age and mineral amount p<0.00 between (diabetes+obese) and obese groups. Besides, when these patient groups and control group were analyzed, there were significant difference between most parameters. In terms of education level among the illiterate and university graduates; fat mass kg, fat percentage, internal lubrication, body mass index, water percentage, protein mass percentage, mineral percentage p<0.05, significant statistically difference were observed. This difference especially may result

  10. Reference Centile Curves for Body Fat Percentage, Fat-free Mass, Muscle Mass and Bone Mass Measured by Bioelectrical Impedance in Asian Indian Children and Adolescents.

    Science.gov (United States)

    Chiplonkar, Shashi; Kajale, Neha; Ekbote, Veena; Mandlik, Rubina; Parthasarathy, Lavanya; Borade, Ashwin; Patel, Pinal; Patel, Prerna; Khadilkar, Vaman; Khadilkar, Anuradha

    2017-12-15

    To create gender-specific percentile curves for percent body fat (%BF) by Bio electrical Impedance Analysis (BIA) for screening adiposity and risk of hypertension in Indian children and generate reference curves for percent fat-free mass (%FFM), muscle mass (%LM) and bone mineral content (BMC) by using bioelectrical impedance. Secondary analysis of data from previous multicenter cross-sectional studies. Private schools from five regions of India. A random sample of 3850 healthy school children (2067 boys) (5-17 yr) from private schools in five major Indian cities. Anthropometry, blood pressure (BP) and body composition were measured by bioelectrical impedance. Reference curves were generated by the LMS method. %BF, %FFM, %LM, BMC and BP. Median %BF increased by 6% from 5 to 13 years of age and declined (around 2%) up to 17 years in boys. In girls, %BF increased by 8% from 5 to 14 years and thereafter declined by 3%. Based upon the risk of hypertension, the new cut-offs of 75th and 85th percentile of %BF were proposed for detecting over fatness and excess fatness in children. Median %FFM was 90% at 5 yrs and decreased till 12 years, and then showed a slight increase to 84% at 17 yrs in boys. In girls, it was 86% at 5 yrs and decreased till 15 yrs, and plateaued at 71.8% at 17 yrs. Reference curves for percent body fat for Indian children would be useful to screen children for health risk in clinical set up.

  11. Discordance between bioelectrical impedance vector analysis and the new ESPEN definition of malnutrition for the diagnosis of hospital malnutrition.

    Science.gov (United States)

    Dehesa-López, Edgar; Martínez-Felix, Jesús Israel; Ruiz-Ramos, Arturo; Atilano-Carsi, Ximena

    2017-04-01

    No universally accepted diagnostic criteria for malnutrition are available to date. The aim was to assess the concordance for the diagnosis of hospital malnutrition between the bioelectrical impedance vector analysis (BIVA) and the new definition of malnutrition proposed by the European Society for Clinical Nutrition and Metabolism (ESPEN). A total of 140 adult hospitalized patients were included. The malnutrition risk was assessed by the Nutritional Risk Screening. The ESPEN malnutrition criteria (body mass index (BMI) malnutrition was diagnosed using the BIVA method. Diagnostic concordance between the BIVA and the new ESPEN definition was assessed with the Kappa coefficient. The malnutrition prevalence was higher with the BIVA vs ESPEN definition (22.1% vs 13.6%) in the global population and was similar (12.8% vs 12.1%) in the population at risk of malnutrition. The diagnostic performance of the BIVA was acceptable, with higher sensitivity in patients with fluid overload (FO) and more specificity in euvolemic patients. Diagnostic concordance between the BIVA and the ESPEN definition was poor for the global population (kappa = 0.56) and the population at risk of malnutrition (kappa = 0.67) but was acceptable in patients with FO (kappa = 0.78). However, the discordant BIVA+/ESPEN- patients classified as false positives for BIVA showed clinical and body composition data (low FFMI, low phase angle) consistent with malnutrition. According to the clinical and bioelectrical characteristics of the discordant BIVA+/ESPEN- patients, the BIVA could perform better that the new ESPEN definition for the diagnosis of hospital malnutrition, which should be confirmed with other studies. Copyright © 2017 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

  12. Dielectric relaxation and ac conduction in γ-irradiated UHMWPE/MWCNTs nano composites: Impedance spectroscopy analysis

    International Nuclear Information System (INIS)

    Maqbool, Syed Asad; Mehmood, Malik Sajjad; Mukhtar, Saqlain Saqib; Baluch, Mansoor A.; Khan, Shamim; Yasin, Tariq; Khan, Yaqoob

    2017-01-01

    The dielectric behavior of γ-irradiated ultra-high molecular weight polyethylene (UHMWPE) and its nano composites (NCs) with γ-ray modified multi wall carbon nano tubes (γ-MWCNTs) and MWCNTs had been studied using impedance spectroscopy. The study had been carried out in the frequency range of 20–2 MHz at room temperature. All samples (pure and NCs) were prepared in the form of sheets and irradiated with γ-dose of 50 kGy and 100 kGy, respectively. The comprehensive analysis of results revealed that resistivity of UHMWPE for conduction decreased on irradiation and incorporation of MWCNTs (whether γ ray modified or un-modified) due to the radiation induced damage and conductive networks induced by MWCNTs. At low frequency range a significant increase in the dielectric constant had been observed because of irradiation and addition of MWNCTs. The trend of loss tangent and ac conductivity for each investigated sample depended on resistivity offered and had a decreasing trend as a function of frequency. Moreover, dissipation factor increased with the incorporation of MWNCTs and irradiation from 0.12 to 0.22. In addition to this, non-frequency dependent static dielectric constant was also found to increase with irradiation and incorporation of MWCNTs. The relaxation time was found to increase from 1.2 to 4.3 ms due to hindrance offered by radiation induced mutual cross linking of PE chains and polymer-MWNCTs bindings. - Highlights: • The resistivity for conduction in pristine UHMWPE is decreased with γ-irradiation. • Conduction in PE/MWCNTs nanocomposites increased due to MWCNTs addition. • Static dielectric constant of UHMWPE increased with γ-irradiation. • Static dielectric constant of UHMWPE increased due to MWCNTs incorporation.

  13. Dielectric properties, impedance analysis and modulus behavior of CaTiO{sub 3} ceramic prepared by solid state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Y.J., E-mail: yjeng_86@hotmail.com [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hassan, J., E-mail: jumiah@science.upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, M., E-mail: mansor@science.upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2013-09-15

    Highlights: •A single phase orthorhombic CaTiO{sub 3} structure with sub-micron grains is produced. •The frequency exponent ‘s’ is temperature dependent and explained by CBH model. •The dielectric constant and loss tangent are frequency and temperature dependent. •The modulus plot reveals the presence of thermally activated dielectric relaxation. •Cole-cole plot reveals two primary relaxation processes exist in the sample. -- Abstract: Calcium titanate (CaTiO{sub 3}) with the general formula for perovskites, ABO{sub 3}, is of technological importance, particularly with regard to dielectric properties. In this work, CaTiO{sub 3} ceramic material was prepared by the conventional solid state reaction method. The dielectric properties, impedance characteristics and modulus behavior of the CaTiO{sub 3} ceramic material sintered at 1240 °C were investigated in the frequency range of 10{sup −2}–10{sup 6} Hz and temperature range of 100–250 °C. The XRD analysis of the sintered CaTiO{sub 3} shows that it is an orthorhombic structure with lattice parameters a = 5.4398 Å, b = 7.6417 Å, and c = 5.3830 Å. The FESEM micrograph shows a significant difference in grain size distribution ranging from 0.26 to 2.32 μm. The AC conductivity, σ{sub AC}, is found to increase with increasing temperature within the frequency range of 10{sup −2}–10{sup 6} Hz confirming the hopping of electrons to be the conduction mechanism. Due to the decreasing values of the frequency exponent s with increasing temperature, the results of the σ{sub AC} are discussed using the correlated barrier height (CBH) model. For dielectric studies, the dielectric constant, ε′ is found to decrease with increasing frequency. In the whole temperature range of 100–250 °C, high and low frequency plateau are observed. Each converges at high frequency (>10{sup 5} Hz) for all the temperatures. The frequency dependence of loss tangent, tan δ, decreases with rise in temperature, with the

  14. Impedance-Based Stability Analysis in Grid Interconnection Impact Study Owing to the Increased Adoption of Converter-Interfaced Generators

    Directory of Open Access Journals (Sweden)

    Youngho Cho

    2017-09-01

    Full Text Available This study investigates the emerging harmonic stability concerns to be addressed by grid planners in generation interconnection studies, owing to the increased adoption of renewable energy resources connected to the grid via power electronic converters. The wideband and high-frequency electromagnetic transient (EMT characteristics of these converter-interfaced generators (CIGs and their interaction with the grid impedance are not accurately captured in the typical dynamic studies conducted by grid planners. This paper thus identifies the desired components to be studied and subsequently develops a practical process for integrating a new CIG into a grid with the existing CIGs. The steps of this process are as follows: the impedance equation of a CIG using its control dynamics and an interface filter to the grid, for example, an LCL filter (inductor-capacitor-inductor type, is developed; an equivalent impedance model including the existing CIGs nearby and the grid observed from the point of common coupling are derived; the system stability for credible operating scenarios is assessed. Detailed EMT simulations validate the accuracy of the impedance models and stability assessment for various connection scenarios. By complementing the conventional EMT simulation studies, the proposed analytical approach enables grid planners to identify critical design parameters for seamlessly integrating a new CIG and ensuring the reliability of the grid.

  15. A comparison and accuracy analysis of impedance-based temperature estimation methods for Li-ion batteries

    NARCIS (Netherlands)

    Beelen, H.P.G.J.; Raijmakers, L.H.J.; Donkers, M.C.F.; Notten, P.H.L.; Bergveld, H.J.

    2016-01-01

    In order to guarantee safe and proper use of Lithium-ion batteries during operation, an accurate estimate of the battery temperature is of paramount importance. Electrochemical Impedance Spectroscopy (EIS) can be used to estimate the battery temperature and several EIS-based temperature estimation

  16. Application of the Method of Auxiliary Sources for the Analysis of Plane-Wave Scattering by Impedance Spheres

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza; Breinbjerg, Olav

    2002-01-01

    The Method of Auxiliary Sources (MAS) is applied to 3D scattering problems involving spherical impedance scatterers. The MAS results are compared with the reference spherical wave expansion (SWE) solution. It is demonstrated that good agreement is achieved between the MAS and SWE results....

  17. Relationship between body fat percentage determined by bioelectrical impedance analysis and metabolic risk factors in Syrian male adolescents (18–19 years

    Directory of Open Access Journals (Sweden)

    Al-Bachir Mahfouz

    2017-03-01

    Full Text Available The association between increasing obesity and metabolic syndrome among adolescent and the adverse consequences in adulthood including type-2 diabetes and coronary heart disease is well documented. The main objectives of this study were to evaluate the major metabolic risk factors and some clinical important parameters in Syrian male adolescents (18-19 years old, and to assess the correlations between BF% determined by BIA-man prediction equation and metabolic risk factors in the same group. The correlations between body fat percentage (BF% based on BIA-man predictive equations, blood pressure, fasting blood sugar (FBS, cholesterol (Chol, low density lipoprotein cholesterol (LDL-C, high density lipoprotein cholesterol (HDL-C, triglycerides (TG, Hematocrit (Ht, and hemoglobin (Hb in 1596 healthy Syrian adolescents aged 18-19 years and the mean values of these parameters were examined. Data showed that, DBP, Chol, TG, LDL and TG/HDL-C were significantly (p<0.05 higher in overweight and obese subjects in compression to normal weight cases. Whereas, SBP, FBS and Ht were significantly (p<0.05 higher in obese subjects in compression to normal weight. However, all measured variable related to metabolic syndrome risk factors increased with increasing the BF% determined by BIA-man. The present study suggests that % BF by BIA-man is a good predictor of metabolic risks factors for Syrian adolescents.

  18. High temperature impedance spectroscopy of barium stannate

    Indian Academy of Sciences (India)

    ... differential thermal analysis, thermogravimetric analysis and Fourier transform infrared techniques. Electrical properties were studied using a.c. impedance spectroscopy technique in the temperature range of 50–650 °C and frequency range of 10 Hz–13 MHz. The complex impedance plots at temperature ≥ 300 °C show ...

  19. Gender differences and age-related changes in body fat mass in Tibetan children and teenagers: an analysis by the bioelectrical impedance method.

    Science.gov (United States)

    Zhang, Hai-Long; Fu, Qiang; Li, Wen-Hui; Liu, Su-Wei; Zhong, Hua; Duoji, Bai-Ma; Zhang, Mei-Zhi; Lv, Po; Xi, Huan-Jiu

    2015-01-01

    We aimed to obtain the fat base value and the fat distribution characteristics of Tibetan children and teenagers by estimating their body fat content with the bioelectrical impedance method. We recruited 1427 healthy children and teenagers by a stratified cluster sampling method. By using bioelectrical impedance analysis, we obtained various values relevant to fat. We found that total body fat mass and the fat mass of various body parts increased with age in boys and girls. Yet there were no differences between age groups until 11 years. However, fat mass increased quickly between 11 and 18 years, and significant differences were seen between adolescent boys and girls; all fat indices were higher in girls than in boys (pfat in Tibetan children and teenagers in Tibet is related to age and gender related hormone secretion, which reflects the physiological characteristics in different developmental stages.

  20. Tekst (dźwiękowy Mirona Białoszewskiego

    Directory of Open Access Journals (Sweden)

    Andrzej Hejmej

    2007-08-01

    Full Text Available The paper focuses on the interaction between the visual text and sound-text in the works of Miron Białoszewski, especially in his Separate Theatre. In this case, considerations on the subject of textuality show a relation between Białoszewskim linguistics experiments and contemporary sound poetry. In essence, the sound poetry as an artistic practice (particularly, the sound poetry of Bernard Heidsieck appears to be an important and inspiring context for interpretation of Białoszewskim text. Finally, based on the problem of sound-text, many similarities are found between Miron Białoszewski and Bernard Heidsieck.

  1. Analysis of specification of an electrode type sensor equivalent circuit on the base of impedance spectroscopy simulation

    International Nuclear Information System (INIS)

    Ogurtsov, V I; Mathewson, A; Sheehan, M M

    2005-01-01

    Simulation of electrochemical impedance spectroscopy (EIS) based on a LabVIEW model of a complex impedance measuring system in the frequency domain has been investigated to specify parameters of Randle's equivalent circuit, which is ordinarily used for electrode sensors. The model was based on a standard system for EIS instrumentation and consisted of a sensor modelled by Randle's equivalent circuit, a source of harmonic frequency sweep voltage applied to the sensor and a transimpedance amplifier, which transformed the sensor current to voltage. It provided impedance spectroscopy data for different levels of noise, modelled by current and voltage equivalent noise sources applied to the amplifier input. The noise influence on Randle's equivalent circuit specification was analysed by considering the behaviour of the approximation error. Different metrics including absolute, relative, semilogarithmic and logarithmic based distance between complex numbers on a complex plane were considered and compared to one another for evaluating this error. It was shown that the relative and logarithmic based metrics provide more reliable results for the determination of circuit parameters

  2. Analysis of specification of an electrode type sensor equivalent circuit on the base of impedance spectroscopy simulation

    Energy Technology Data Exchange (ETDEWEB)

    Ogurtsov, V I; Mathewson, A; Sheehan, M M [Tyndall National Institute, Lee Maltings, Prospect Row, Cork (Ireland)

    2005-01-01

    Simulation of electrochemical impedance spectroscopy (EIS) based on a LabVIEW model of a complex impedance measuring system in the frequency domain has been investigated to specify parameters of Randle's equivalent circuit, which is ordinarily used for electrode sensors. The model was based on a standard system for EIS instrumentation and consisted of a sensor modelled by Randle's equivalent circuit, a source of harmonic frequency sweep voltage applied to the sensor and a transimpedance amplifier, which transformed the sensor current to voltage. It provided impedance spectroscopy data for different levels of noise, modelled by current and voltage equivalent noise sources applied to the amplifier input. The noise influence on Randle's equivalent circuit specification was analysed by considering the behaviour of the approximation error. Different metrics including absolute, relative, semilogarithmic and logarithmic based distance between complex numbers on a complex plane were considered and compared to one another for evaluating this error. It was shown that the relative and logarithmic based metrics provide more reliable results for the determination of circuit parameters.

  3. Nonsynchronous Noncommensurate Impedance Transformers

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Kim, K

    2012-01-01

    Nonsynchronous noncommensurate impedance transformers consist of a combination of two types of transmission lines: transmission lines with a characteristic impedance equal to the impedance of the source, and transmission lines with a characteristic impedance equal to the load. The practical...... advantage of such transformers is that they can be constructed using sections of transmission lines with a limited variety of characteristic impedances. These transformers also provide comparatively compact size in applications where a wide transformation ratio is required. This paper presents the data...... matrix approach and experimentally verified by synthesizing a 12-section nonsynchronous noncommensurate impedance transformer. The measured characteristics of the transformer are compared to the characteristics of a conventional tapered line transformer....

  4. FDTD modeling of thin impedance sheets

    Science.gov (United States)

    Luebbers, Raymond J.; Kunz, Karl S.

    1991-01-01

    Thin sheets of resistive or dielectric material are commonly encountered in radar cross section calculations. Analysis of such sheets is simplified by using sheet impedances. In this paper it is shown that sheet impedances can be modeled easily and accurately using Finite Difference Time Domain (FDTD) methods.

  5. Impedance of a nanoantenna

    International Nuclear Information System (INIS)

    Greffet, Jean-Jacques; Laroche, Marine; Marquier, Francois

    2009-01-01

    We introduce a generalized definition of the impedance of a nanoantenna that can be applied to any system. We also introduce a definition of the impedance of a two level system. Using this framework, we establish a link between the electrical engineering and the quantum optics picture of light emission.

  6. RHIC injection kicker impedance

    International Nuclear Information System (INIS)

    Mane, V.; Peggs, S.; Trbojevic, D.; Zhang, W.

    1995-01-01

    The longitudinal impedance of the RHIC injection kicker is measured using the wire method up to a frequency of 3 GHz. The mismatch between the 50 ohm cable and the wire and pipe system is calibrated using the TRL calibration algorithm. Various methods of reducing the impedance, such as coated ceramic pipe and copper strips are investigated

  7. Is the Routine Use of Impedance Analysis for the Diagnosis of Gastro-Esophageal Reflux Disease More Expensive than Conventional pH Monitoring? Cost Analysis of Two Procedures.

    Science.gov (United States)

    Törer, Nurkan; Aytaç, Özgür

    2017-06-01

    Conventional 24-h pH monitoring is the gold standard for the diagnosis of non-erosive, non-acidic gastro-esophageal reflux disease. Multichannel Intraluminal Impedance (MII) analysis markedly improves diagnostic accuracy of non-erosive, non-acidic gastro-esophageal reflux disease. However, MII catheters are more expensive than standard catheters. This study aimed to determine the rates of acid or non-acid reflux and by making a retrospective projection, to predict the costs of two algorithms. We retrospectively reviewed the medical data of 102 patients who presented to our hospital with suspected non-erosive GERD and underwent 24 h impedance/pH-monitoring. Demographic characteristics, Demeester scores, number of reflux episodes, and results of impedance analysis were recorded. According to these data, cost was calculated either for the scenario in which impedance measurement was performed solely or following a negative conventional pH monitoring. Thirty-seven of all 102 patients (36.3 %) had a Demeester score greater than 14.7. These patients were assigned as group 1 (acid reflux). The impedance analysis of the remaining 65 patients detected 34 patients (33.3 %) to have more than 50 reflux episodes over a period of 24 h and assigned as Group 2, and 31 patients (30.4 %) had no reflux (group 3). The cost of the single- step algorithm using MII catheter was calculated as $15,300, while the total cost of two-step scenario would have been predicted as $16,890. Our study showed that an initial conventional pH monitoring can make the diagnosis of GERD in only one third of the patients with suspected non-erosive GERD. In nearly two-thirds of patients, however, repeated procedures and use of impedance catheters are needed. It is clear that this algorithm has certain drawbacks with regard to cost, patient comfort, and workforce loss.

  8. 43 CFR 30.128 - What happens if an error in BIA's estate inventory is alleged?

    Science.gov (United States)

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false What happens if an error in BIA's estate... INDIAN PROBATE HEARINGS PROCEDURES Judicial Authority and Duties § 30.128 What happens if an error in BIA's estate inventory is alleged? This section applies when, during a probate proceeding, an interested...

  9. 25 CFR 171.310 - Can I use water delivered by BIA for livestock purposes?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Can I use water delivered by BIA for livestock purposes? 171.310 Section 171.310 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER IRRIGATION OPERATION AND MAINTENANCE Water Use § 171.310 Can I use water delivered by BIA for livestock...

  10. 25 CFR 166.901 - How will the BIA select an agriculture intern?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false How will the BIA select an agriculture intern? 166.901... PERMITS Agriculture Education, Education Assistance, Recruitment, and Training § 166.901 How will the BIA select an agriculture intern? (a) The purpose of the agriculture intern program is to ensure the future...

  11. 25 CFR 171.305 - Will BIA provide leaching service to me?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Will BIA provide leaching service to me? 171.305 Section... OPERATION AND MAINTENANCE Water Use § 171.305 Will BIA provide leaching service to me? (a) We may provide you leaching service if: (1) You submit a written plan that documents how soil salinity limits your...

  12. 76 FR 4369 - Interim Deputation Agreements; Interim BIA Adult Detention Facility Guidelines

    Science.gov (United States)

    2011-01-25

    ... Deputation Agreements are effective on January 25, 2011. FOR FURTHER INFORMATION CONTACT: Charles Addington... http://www.bia.gov/WhoWeAre/BIA/OJS/index.htm . The documents were the subject of tribal consultation in November and December 2010. The Office of Justice Services continues consultation on the Tribal...

  13. 25 CFR 170.401 - What is BIA's role in transportation planning?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false What is BIA's role in transportation planning? 170.401... RESERVATION ROADS PROGRAM Planning, Design, and Construction of Indian Reservation Roads Program Facilities Transportation Planning § 170.401 What is BIA's role in transportation planning? Except as provided in § 170.402...

  14. Rietveld and impedance analysis of cold and hot rolled duplex and lean duplex steels for application in paper and pulp industry

    Energy Technology Data Exchange (ETDEWEB)

    Esteves, Luiza; Lins, Vanessa de Freitas Cunha, E-mail: luizaeq@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Quimica; Paiva, Paulo Renato Perdigao [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET), Belo Horizonte, MG (Brazil); Viana, Adolfo Kalergis do Nascimento [APERAM South America, Timoteo, MG (Brazil)

    2017-01-15

    In this study, X-Ray Diffraction (XRD) and Rietveld Refinement were performed to identify and quantify the ferrite and austenite phase of cold and hot rolled duplex stainless steels (UNS S31803) and lean duplex stainless steels (UNS S32304). Electrochemical impedance spectroscopy (EIS) was applied to evaluate the chemical behavior of duplex and lean duplex stainless steels in white, green, and black liquors of paper and pulp industry. Rietveld analysis results showed a higher austenite content than the standard limit for duplex steels in the hot rolled condition. The hot rolling condition plays a major role in improving corrosion resistance in white liquor mainly for the lean duplex steel. (author)

  15. Rietveld and impedance analysis of cold and hot rolled duplex and lean duplex steels for application in paper and pulp industry

    International Nuclear Information System (INIS)

    Esteves, Luiza; Lins, Vanessa de Freitas Cunha; Viana, Adolfo Kalergis do Nascimento

    2017-01-01

    In this study, X-Ray Diffraction (XRD) and Rietveld Refinement were performed to identify and quantify the ferrite and austenite phase of cold and hot rolled duplex stainless steels (UNS S31803) and lean duplex stainless steels (UNS S32304). Electrochemical impedance spectroscopy (EIS) was applied to evaluate the chemical behavior of duplex and lean duplex stainless steels in white, green, and black liquors of paper and pulp industry. Rietveld analysis results showed a higher austenite content than the standard limit for duplex steels in the hot rolled condition. The hot rolling condition plays a major role in improving corrosion resistance in white liquor mainly for the lean duplex steel. (author)

  16. Sensitivity analysis of an impedance void meter to the void distribution in annular flow: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Lemonnier, H.; Nakach, R.; Favreau, C.; Selmer-Olsen, S. (CEA Centre d' Etudes Nucleaires de Grenoble, 38 (France). Service d' Etudes Thermohydrauliques)

    1991-04-01

    Impedance void meters are frequently used to measure the are-averaged void fraction in pipes. This is primarily for two reasons: firstly, this method is non-instrusive since the measurement can be made by electrodes flush mounted in the walls, and secondly, the signal processing equipment is simple. Impedance probes may be calibrated by using a pressure drop measurement or a quick closing valve system. In general, little attention is paid to void distribution effects. It can be proved that in annular flow, the departure from radial symmetry has a strong influence on the measured mean film thickness. This can be easily demonstrated by solving the Laplace equation for the electrical potential by simple analytical methods. When some spatial symmetry conditions are encountered, it is possible to calculate directly the conductance of the two-phase medium without a complete calculation of the potential. A solution of this problem by using the separation of variables technique is also presented. The main difficulty with this technique is the mixed nature of the boundary conditions: the boundary condition is both of Neumann and of Drichlet type on the same coordinate curve. This formulation leads to a non-separable problem, which is solved by truncating an infinite algebraic set of linear equations. The results, although strictly valid in annular flow, may give the correct trends when applied to bubbly flow. Finally, the theory provides an error estimate and a design criterion to improve the probe reliability. (orig.).

  17. Sensitivity analysis of an impedance void meter to the void distribution in annular flow: A theoretical study

    International Nuclear Information System (INIS)

    Lemonnier, H.; Nakach, R.; Favreau, C.; Selmer-Olsen, S.

    1991-01-01

    Impedance void meters are frequently used to measure the are-averaged void fraction in pipes. This is primarily for two reasons: firstly, this method is non-instrusive since the measurement can be made by electrodes flush mounted in the walls, and secondly, the signal processing equipment is simple. Impedance probes may be calibrated by using a pressure drop measurement or a quick closing valve system. In general, little attention is paid to void distribution effects. It can be proved that in annular flow, the departure from radial symmetry has a strong influence on the measured mean film thickness. This can be easily demonstrated by solving the Laplace equation for the electrical potential by simple analytical methods. When some spatial symmetry conditions are encountered, it is possible to calculate directly the conductance of the two-phase medium without a complete calculation of the potential. A solution of this problem by using the separation of variables technique is also presented. The main difficulty with this technique is the mixed nature of the boundary conditions: the boundary condition is both of Neumann and of Drichlet type on the same coordinate curve. This formulation leads to a non-separable problem, which is solved by truncating an infinite algebraic set of linear equations. The results, although strictly valid in annular flow, may give the correct trends when applied to bubbly flow. Finally, the theory provides an error estimate and a design criterion to improve the probe reliability. (orig.)

  18. Directed weighted network structure analysis of complex impedance measurements for characterizing oil-in-water bubbly flow.

    Science.gov (United States)

    Gao, Zhong-Ke; Dang, Wei-Dong; Xue, Le; Zhang, Shan-Shan

    2017-03-01

    Characterizing the flow structure underlying the evolution of oil-in-water bubbly flow remains a contemporary challenge of great interests and complexity. In particular, the oil droplets dispersing in a water continuum with diverse size make the study of oil-in-water bubbly flow really difficult. To study this issue, we first design a novel complex impedance sensor and systematically conduct vertical oil-water flow experiments. Based on the multivariate complex impedance measurements, we define modalities associated with the spatial transient flow structures and construct modality transition-based network for each flow condition to study the evolution of flow structures. In order to reveal the unique flow structures underlying the oil-in-water bubbly flow, we filter the inferred modality transition-based network by removing the edges with small weight and resulting isolated nodes. Then, the weighted clustering coefficient entropy and weighted average path length are employed for quantitatively assessing the original network and filtered network. The differences in network measures enable to efficiently characterize the evolution of the oil-in-water bubbly flow structures.

  19. 25 CFR 170.614 - Can a tribe receive funds before BIA publishes the notice of funding availability?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Can a tribe receive funds before BIA publishes the notice... Contracts and Agreements Under Isdeaa § 170.614 Can a tribe receive funds before BIA publishes the notice of funding availability? A tribe can receive funds before BIA publishes the notice of funding availability...

  20. The Analysis and Structuring of the Causes Impeding the Introduction of Advanced Technologies for Exchange Grain Trading

    Directory of Open Access Journals (Sweden)

    Vinnychenko Olena V

    2015-03-01

    Full Text Available In the article the main causes impeding the development and introduction of advanced technologies for grain trading on commodity exchanges in Ukraine have been identified and structured. The generalization of existing shortcomings in operation of the domestic commodity exchanges has served the basis for the model, within which there were built: a directed graph of correlations between the above mentioned shortcomings in the operation of exchanges, the matrix of dependency and reachability. The causes have been identified and structured, the main ones being determined, which, in turn, makes it possible to carry out the correct sequence of actions and emphasize the primary issues requiring priority solutions at making management decisions in order to promote the grain exchange market. The suggested approach clearly shows the correlation between the existing causes and sequence of their elimination.

  1. Calibration of bioelectrical impedance analysis for body composition assessment in Ethiopian infants using air-displacement plethysmography

    DEFF Research Database (Denmark)

    Christensen, Rasmus Wibæk; Kæstel, Pernille; Skov, R.

    2015-01-01

    and noninvasive method for assessing BC. However, very little research has been conducted in low- and middle-income populations, where efforts to prevent or treat malnutrition in early life are a public health priority. We aimed to develop equations for predicting fat-free mass (FFM) and fat mass (FM) based......, age and an impedance index (L(2)/Z50) were predictors. Prediction equations were developed using stepwise multiple linear regression and the accuracy was evaluated with a 10-fold cross-validation approach. RESULTS: A linear regression model based on body weight, age and sex predicted FFM, estimated...... model fit for predicting FFM compared with a model already comprising weight, sex and age. CONCLUSIONS: The derived equations predicted FFM with acceptable accuracy and may be used in future field surveys, epidemiological studies and clinical trials conducted in similar sub-Saharan African population...

  2. Impedance and Collective Effects

    CERN Document Server

    Metral, E; Rumolo, R; Herr, W

    2013-01-01

    This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Chapter '4 Impedance and Collective Effects' with the content: 4 Impedance and Collective Effects Introduction 4.1 Space Charge 4.2 Wake Fields and Impedances 4.3 Coherent Instabilities 4.4 Landau Damping 4.5 Two-Stream Effects (Electron Cloud and Ions) 4.6 Beam-Beam Effects 4.7 Numerical Modelling

  3. Bioelectrical impedance vectorial analysis and nutritional status of older women according. 10.5007/1980-0037.2011v13n6p415

    Directory of Open Access Journals (Sweden)

    Sandra Maria Lima Ribeiro

    2011-11-01

    Full Text Available The objective of the present study was to compare and discuss the nutritional status of older women according to different categories of BMI. Additionally, the study was aimed at introducing the bioelectrical impedance vector analysis (BIVA as a tool to assess the nutritional status. Thirty-two women (60 years or older, physically independent, and with moderate level of physical activity were divided into three groups according toBMI classification: G1 (BMI28 Kg/ m2. The following variables were analyzed as indicators of nutritional status: body mass and height to calculate BMI, waist circumference (WC, hip circumference (HC, waisthipratio (WHR, bioelectrical impedance (BIVA, resting energy expenditure (REE, biochemical markers of nutritional status (glucose, total cholesterol, and fractions, IGF-1, and leptin. The groups were compared using ANOVA and the Hotelling’s T 2 test for vector analysis. The main findings based on vector displacement showed lower reactance and higher resistance in G1. G3 showed the highest values of CC and leptin, and also lower REE. Therefore, higher BMI suggested at the same time higher cell mass and higher risk of developing chronic diseases. In turn, lower BMI values suggested reduced fat-free body mass. These results confirm the search for specific classification of BMI for the elderly and suggest the BIVA as a viable alternative in physical and nutritional assessment.

  4. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-01-01

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible

  5. 23 CFR 661.35 - What percentage of IRRBP funding is available for use on BIA and Tribally owned IRR bridges, and...

    Science.gov (United States)

    2010-04-01

    ... BIA and Tribally owned IRR bridges, and non-BIA owned IRR bridges? 661.35 Section 661.35 Highways... RESERVATION ROAD BRIDGE PROGRAM § 661.35 What percentage of IRRBP funding is available for use on BIA and Tribally owned IRR bridges, and non-BIA owned IRR bridges? (a) Up to 80 percent of the available funding...

  6. Electrical Impedance Tomography Technology

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal for the Electrical Impedance Tomography Technology (EITT) project is to develop a reliable portable, lightweight device providing two-dimensional...

  7. Impedance and component heating

    CERN Document Server

    Métral, E; Mounet, N; Pieloni, T; Salvant, B

    2015-01-01

    The impedance is a complex function of frequency, which represents, for the plane under consideration (longitudinal, horizontal or vertical), the force integrated over the length of an element, from a “source” to a “test” wave, normalized by their charges. In general, the impedance in a given plane is a nonlinear function of the test and source transverse coordinates, but it is most of the time sufficient to consider only the first few linear terms. Impedances can influence the motion of trailing particles, in the longitudinal and in one or both transverse directions, leading to energy loss, beam instabilities, or producing undesirable secondary effects such as excessive heating of sensitive components at or near the chamber wall, called beam-induced RF heating. The LHC performance limitations linked to impedances encountered during the 2010-2012 run are reviewed and the currently expected situation during the HL-LHC era is discussed.

  8. The LEP impedance model

    Energy Technology Data Exchange (ETDEWEB)

    Zotter, B [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    This report describes a number of measurements and computations of the impedance of the Large Electron Positron collider LEP at CERN. The work has been performed over several years, together with D. Brandt, K. Cornelis, A. Hofmann, G. Sabbi and many others. The agreement between measurements of single bunch instabilities on the machine and computer simulations is in general excellent and gives confidence in the impedance model used. (author)

  9. CSR Impedance for Non-Ultrarelativistic Beams

    International Nuclear Information System (INIS)

    Li, Rui; Tsai, Cheng Y.

    2015-09-01

    For the analysis of the coherent synchrotron radiation (CSR)-induced microbunching gain in the low energy regime, such as when a high-brightness electron beam is transported through a low-energy merger in an energy-recovery linac (ERL) design, it is necessary to extend the CSR impedance expression in the ultrarelativistic limit to the non-ultrarelativistic regime. This paper presents our analysis of CSR impedance for general beam energies.

  10. Electrical impedance tomography: topology optimization

    International Nuclear Information System (INIS)

    Miranda, Lenine Campos

    2013-01-01

    The Electrical Impedance Tomography (EIT) is a study of body parts who use electric current. Is studied through computers resistance or conductivity of these parts, producing an image used for medical diagnosis. A body is wrapped in a blanket placed with small electrodes and receivers of electric current, potential difference. Based on data obtained from a series of measurements at the electrodes, one by one, sending and receiving, you can perform a numerical phantom, where each 'voxel' of the image formed computationally represents the impedance of biological tissue. In Brazil, studies on electrical impedance tomography (EIT) has not yet started. Such equipment are measured tensions - potential difference - between each electrode / sensor one by one, as a way to Simple Combinatorial Analysis. The sequence and the way it is measured strains are in the final image quality. Finite Element Method Interactive, whose algorithm is based on Dialectical Method. We use an initial function with the objective of maximizing the data quantitatively, for better qualitative analysis. Topology Optimization methods are used to improve the image reconstruction. Currently the study is quite primitive related to the theory that shows how to power the new science studied. The high quality images requires a difficulty in obtaining. This work is not intended for detailed for analysis in any tissue or organ specific, but in general terms. And the formation of the 2D image. 3D need a reconstructor to part. (author)

  11. Electrical and impedance spectroscopy analysis of sol-gel derived spin coated Cu2ZnSnS4 solar cell

    Science.gov (United States)

    Gupta, Goutam Kumar; Garg, Ashish; Dixit, Ambesh

    2018-01-01

    We carried out electrical and impedance studies on solution derived Al:ZnO/ZnO/CdS/Cu2ZnSnS4/Mo/Glass multilayered solar cell structures to understand their impact on photovoltaic performance. The Cu2ZnSnS4 layer is synthesized on a molybdenum (Mo) coated soda lime glass substrate as an absorber and characterized intensively to optimize the absorber physical properties. The optimized Cu2ZnSnS4 is p-type with 5.8 × 1017 cm-3 hole carrier concentration. The depletion width of the junction is around 20.5 nm and the diffusion capacitance is ˜35.5 nF for these devices. We observed relatively large minority carrier life time ˜23 μs for these structures using open voltage decay analysis. The measured Cu2ZnSnS4/MoS2 and Cu2ZnSnS4/CdS interface resistances are 7.6 kΩ and 12.5 kΩ, respectively. The spatial inhomogeneities are considered and the corresponding resistance is ˜11.4 kΩ. The impedance measurements suggest that in conjunction with series resistance ˜350 Ω, the interface and spatial inhomogeneity resistances also give a significant contribution to the photovoltaic performance.

  12. Application of bioelectrical impedance vector analysis (BIVA in dogs: a preliminary study on gender-related differences

    Directory of Open Access Journals (Sweden)

    Rebecca Ricci

    2010-01-01

    Full Text Available In this preliminary study, BIVA has been performed on 17 healthy Italian Hound dogs, 10 males (M and 7 females (F, in order to verify if gender-related differences can be detected. Only in F higher reactance (Xc values (F: 46.4 vs M: 37.7, P<0.05 and a significant negative correlation (-0.80, P<0.05 between BCS and resistance (R values were detected. 50%, 75% and 95% tolerance ellipses were calculated both in M and F using average Xc and R values standardized for withers height. Probably due to the low number of subjects used in the present study, the variability of the individual vector distribution (F: 79.6 vs M: 53.0Ohm/m, as well as the mean impedance vector lengtht (F: 548.2 vs M: 498.9Ohm/m, were similar in F and M. The gender-related difference in phase angle values was not significant (F: 0.168 vs M: 0.157, P=ns. In conclusion, the use of BIVA in dogs indicated differences between males and females which should be confirmed by a larger number of subjects.

  13. Three-dimensional forward solver and its performance analysis for magnetic resonance electrical impedance tomography (MREIT) using recessed electrodes

    International Nuclear Information System (INIS)

    Lee, Byung Il; Oh, Suk Hoon; Woo, Eung Je; Lee, Soo Yeol; Cho, Min Hyoung; Kwon, Ohin; Seo, Jin Keun; Lee, June-Yub; Baek, Woon Sik

    2003-01-01

    In magnetic resonance electrical impedance tomography (MREIT), we try to reconstruct a cross-sectional resistivity (or conductivity) image of a subject. When we inject a current through surface electrodes, it generates a magnetic field. Using a magnetic resonance imaging (MRI) scanner, we can obtain the induced magnetic flux density from MR phase images of the subject. We use recessed electrodes to avoid undesirable artefacts near electrodes in measuring magnetic flux densities. An MREIT image reconstruction algorithm produces cross-sectional resistivity images utilizing the measured internal magnetic flux density in addition to boundary voltage data. In order to develop such an image reconstruction algorithm, we need a three-dimensional forward solver. Given injection currents as boundary conditions, the forward solver described in this paper computes voltage and current density distributions using the finite element method (FEM). Then, it calculates the magnetic flux density within the subject using the Biot-Savart law and FEM. The performance of the forward solver is analysed and found to be enough for use in MREIT for resistivity image reconstructions and also experimental designs and validations. The forward solver may find other applications where one needs to compute voltage, current density and magnetic flux density distributions all within a volume conductor

  14. Impedance spectroscopic analysis of composite electrode from activated carbon/conductive materials/ruthenium oxide for supercapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Taer, E.; Awitdrus,; Farma, R. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Physics, Faculty of Mathematics and Natural Sciences, University of Riau, 28293 Pekanbaru, Riau (Indonesia); Deraman, M., E-mail: madra@ukm.my; Talib, I. A.; Ishak, M. M.; Omar, R.; Dolah, B. N. M.; Basri, N. H.; Othman, M. A. R. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Kanwal, S. [ICCBS, H.E.J. Research Institute of Chemistry, University of Karachi, 75270 Karachi (Pakistan)

    2015-04-16

    Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H{sub 2}SO{sub 4} electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g{sup −1} respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g{sup −1}, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.

  15. The missing indels: an estimate of indel variation in a human genome and analysis of factors that impede detection

    Science.gov (United States)

    Jiang, Yue; Turinsky, Andrei L.; Brudno, Michael

    2015-01-01

    With the development of High-Throughput Sequencing (HTS) thousands of human genomes have now been sequenced. Whenever different studies analyze the same genome they usually agree on the amount of single-nucleotide polymorphisms, but differ dramatically on the number of insertion and deletion variants (indels). Furthermore, there is evidence that indels are often severely under-reported. In this manuscript we derive the total number of indel variants in a human genome by combining data from different sequencing technologies, while assessing the indel detection accuracy. Our estimate of approximately 1 million indels in a Yoruban genome is much higher than the results reported in several recent HTS studies. We identify two key sources of difficulties in indel detection: the insufficient coverage, read length or alignment quality; and the presence of repeats, including short interspersed elements and homopolymers/dimers. We quantify the effect of these factors on indel detection. The quality of sequencing data plays a major role in improving indel detection by HTS methods. However, many indels exist in long homopolymers and repeats, where their detection is severely impeded. The true number of indel events is likely even higher than our current estimates, and new techniques and technologies will be required to detect them. PMID:26130710

  16. Impedance analysis of PbS colloidal quantum dot solar cells with different ZnO nanowire lengths

    Science.gov (United States)

    Fukuda, Takeshi; Takahashi, Akihiro; Wang, Haibin; Takahira, Kazuya; Kubo, Takaya; Segawa, Hiroshi

    2018-03-01

    The photoconversion efficiency of colloidal quantum dot (QD) solar cells has been markedly improved by optimizing the surface passivation and device structure, and details of device physics are now under investigation. In this study, we investigated the resistance and capacitance components at the ZnO/PbS-QD interface and inside a PbS-QD layer by measuring the impedance spectrum while the interface area was controlled by changing the ZnO nanowire length. By evaluating the dependence of optical intensity and DC bias voltage on the ZnO nanowire length, only the capacitance was observed to be influenced by the interface area, and this indicates that photoinduced carriers are generated at the surface of PbS-QD. In addition, since the capacitance is proportional to the surface area of the QD, the interface area can be evaluated from the capacitance. Finally, photovoltaic performance was observed to increase with increasing ZnO nanowire length owing to the large interface area, and this result is in good agreement with the capacitance measurement.

  17. Tapping mode microwave impedance microscopy

    KAUST Repository

    Lai, K.

    2009-01-01

    We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately simulated by the finite-element analysis and the result agrees quantitatively to the experimental data on a series of thin-film dielectric samples. The tapping mode microwave imaging is also superior to the contact mode in that the thermal drift in a long time scale is totally eliminated and an absolute measurement on the dielectric properties is possible. We demonstrated tapping images on working nanodevices, and the data are consistent with the transport results. © 2009 American Institute of Physics.

  18. Validity of Standing Posture Eight-electrode Bioelectrical Impedance to Estimate Body Composition in Taiwanese Elderly

    Directory of Open Access Journals (Sweden)

    Ling-Chun Lee

    2014-09-01

    Conclusion: The results of this study showed that the impedance index and LST in the whole body, upper limbs, and lower limbs derived from DXA findings were highly correlated. The LST and BF% estimated by BIA8 in whole body and various body segments were highly correlated with the corresponding DXA results; however, BC-418 overestimates the participants' appendicular LST and underestimates whole body BF%. Therefore, caution is needed when interpreting the results of appendicular LST and whole body BF% estimated for elderly adults.

  19. Impeded Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Joachim; Liu, Jia [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Slatyer, Tracy R. [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States); Wang, Xiao-Ping [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Xue, Wei [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

    2016-12-12

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  20. Impeded Dark Matter

    International Nuclear Information System (INIS)

    Kopp, Joachim; Liu, Jia; Slatyer, Tracy R.; Wang, Xiao-Ping; Xue, Wei

    2016-01-01

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  1. Evaluation of the Trajectory Sensitivity Analysis of the DFIG Control Parameters in Response to Changes in Wind Speed and the Line Impedance Connection to the Grid DFIG

    Directory of Open Access Journals (Sweden)

    Mehdi Fooladgar

    2015-01-01

    Full Text Available Economic and environmental conditions often make large stations and transmission lines, restrictions are placed. Small and medium-sized production units connected to existing systems as a strategy is in progress. These units are usually near the center of the load placed and distributed generators (DG famous are the DG are allowed types vary, such as induction generators rack squirrel-connected wind turbines, generators fed induction double mounted wind turbines, fuel cells connected to the system by power electronic converters or synchronous generator connected to the turbine combustion [10]. This way sensitivity analysis in systems of distributed generation (DG is assessed. It is shown that the method can detect the effect of control parameters listed wind turbine connected to a double-fed induction generator (DFIG Badoou the impedance of the changing the speed of on the stability of the transmission line useful system invested. The control parameters of the importance of influencing the behavior of DFIG are divided.

  2. Validity of impedance-based predictions of total body water as measured by 2H dilution in African HIV/AIDS outpatients

    International Nuclear Information System (INIS)

    Diouf, Adama; Idohou Dossou, Nicole; Wade, Salimata; Gartner, Agnes; Sanon, Dominique Alexis; Bluck, Les; Wright, Antony

    2009-01-01

    Measurements of body composition are crucial in identifying HIV-infected patients at risk of malnutrition. No information is available on the validity of indirect body composition methods in African HIV-infected outpatients. Our aim was to test the validity of fifteen published equations, developed in whites, African-Americans and/or Africans who were or not HIV-infected, for predicting total body water (TBW) from bioelectrical impedance analysis (BIA) in HIV-infected patients. The second aim was to develop specific predictive equations. Thirty-four HIV-infected patients without antiretroviral treatment and oedema at the beginning of the study (age 39 (SD 7) years, BMI 18.7 (SD 3.7) kg/m2, TBW 30.4 (SD 7.2 kg) were measured at inclusion then 3 and 6 months later. In the resulting eighty-eight measurements, we compared TBW values predicted from BIA to those measured by 2H dilution. Range of bias values was 0.1-4.3, and errors showed acceptable values (2.2-3.4 kg) for fourteen equations and a high value (10.4) for one equation. Two equations developed in non-HIV-infected subjects showed non-significant bias and could be used in African HIV-infected patients. In the other cases, poor agreement indicated a lack of validity. Specific equations developed from our sample showed a higher precision of TBW prediction when using resistance at 1000kHz (1.7kg) than at 50kHz (2.3kg), this latter precision being similar to that of the valid published equations (2.3 and 2.8kg). The valid published or developed predictive equations should be cross-validated in large independent samples of African HIV-infected patients. (Authors)

  3. Are ethnic and gender specific equations needed to derive fat free mass from bioelectrical impedance in children of South asian, black african-Caribbean and white European origin? Results of the assessment of body composition in children study.

    Directory of Open Access Journals (Sweden)

    Claire M Nightingale

    Full Text Available BACKGROUND: Bioelectrical impedance analysis (BIA is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. METHODS: Cross-sectional study of children aged 8-10 years in London Primary schools including 325 South Asians, 250 black African-Caribbeans and 289 white Europeans with measurements of height, weight and arm-leg impedance (Z; Bodystat 1500. Total body water was estimated from deuterium dilution and converted to FFM. Multilevel models were used to derive three types of equation {A: FFM = linear combination(height+weight+Z; B: FFM = linear combination(height(2/Z; C: FFM = linear combination(height(2/Z+weight}. RESULTS: Ethnicity and gender were important predictors of FFM and improved model fit in all equations. The models of best fit were ethnicity and gender specific versions of equation A, followed by equation C; these provided accurate assessments of ethnic differences in FFM and FM. In contrast, the use of generic equations led to underestimation of both the negative South Asian-white European FFM difference and the positive black African-Caribbean-white European FFM difference (by 0.53 kg and by 0.73 kg respectively for equation A. The use of generic equations underestimated the positive South Asian-white European difference in fat mass (FM and overestimated the positive black African-Caribbean-white European difference in FM (by 4.7% and 10.1% respectively for equation A. Consistent results were observed when the equations were applied to a large external data set. CONCLUSIONS: Ethnic- and gender-specific equations for predicting FFM from BIA provide better estimates of ethnic differences in FFM and FM in children, while generic equations

  4. Are ethnic and gender specific equations needed to derive fat free mass from bioelectrical impedance in children of South asian, black african-Caribbean and white European origin? Results of the assessment of body composition in children study.

    Science.gov (United States)

    Nightingale, Claire M; Rudnicka, Alicja R; Owen, Christopher G; Donin, Angela S; Newton, Sian L; Furness, Cheryl A; Howard, Emma L; Gillings, Rachel D; Wells, Jonathan C K; Cook, Derek G; Whincup, Peter H

    2013-01-01

    Bioelectrical impedance analysis (BIA) is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM) from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. Cross-sectional study of children aged 8-10 years in London Primary schools including 325 South Asians, 250 black African-Caribbeans and 289 white Europeans with measurements of height, weight and arm-leg impedance (Z; Bodystat 1500). Total body water was estimated from deuterium dilution and converted to FFM. Multilevel models were used to derive three types of equation {A: FFM = linear combination(height+weight+Z); B: FFM = linear combination(height(2)/Z); C: FFM = linear combination(height(2)/Z+weight)}. Ethnicity and gender were important predictors of FFM and improved model fit in all equations. The models of best fit were ethnicity and gender specific versions of equation A, followed by equation C; these provided accurate assessments of ethnic differences in FFM and FM. In contrast, the use of generic equations led to underestimation of both the negative South Asian-white European FFM difference and the positive black African-Caribbean-white European FFM difference (by 0.53 kg and by 0.73 kg respectively for equation A). The use of generic equations underestimated the positive South Asian-white European difference in fat mass (FM) and overestimated the positive black African-Caribbean-white European difference in FM (by 4.7% and 10.1% respectively for equation A). Consistent results were observed when the equations were applied to a large external data set. Ethnic- and gender-specific equations for predicting FFM from BIA provide better estimates of ethnic differences in FFM and FM in children, while generic equations can misrepresent these ethnic differences.

  5. Are Ethnic and Gender Specific Equations Needed to Derive Fat Free Mass from Bioelectrical Impedance in Children of South Asian, Black African-Caribbean and White European Origin? Results of the Assessment of Body Composition in Children Study

    Science.gov (United States)

    Nightingale, Claire M.; Rudnicka, Alicja R.; Owen, Christopher G.; Donin, Angela S.; Newton, Sian L.; Furness, Cheryl A.; Howard, Emma L.; Gillings, Rachel D.; Wells, Jonathan C. K.; Cook, Derek G.; Whincup, Peter H.

    2013-01-01

    Background Bioelectrical impedance analysis (BIA) is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM) from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. Methods Cross-sectional study of children aged 8–10 years in London Primary schools including 325 South Asians, 250 black African-Caribbeans and 289 white Europeans with measurements of height, weight and arm-leg impedance (Z; Bodystat 1500). Total body water was estimated from deuterium dilution and converted to FFM. Multilevel models were used to derive three types of equation {A: FFM = linear combination(height+weight+Z); B: FFM = linear combination(height2/Z); C: FFM = linear combination(height2/Z+weight)}. Results Ethnicity and gender were important predictors of FFM and improved model fit in all equations. The models of best fit were ethnicity and gender specific versions of equation A, followed by equation C; these provided accurate assessments of ethnic differences in FFM and FM. In contrast, the use of generic equations led to underestimation of both the negative South Asian-white European FFM difference and the positive black African-Caribbean-white European FFM difference (by 0.53 kg and by 0.73 kg respectively for equation A). The use of generic equations underestimated the positive South Asian-white European difference in fat mass (FM) and overestimated the positive black African-Caribbean-white European difference in FM (by 4.7% and 10.1% respectively for equation A). Consistent results were observed when the equations were applied to a large external data set. Conclusions Ethnic- and gender-specific equations for predicting FFM from BIA provide better estimates of ethnic differences in FFM and FM in children, while generic equations can

  6. Estimation of body composition depends on applied device in patients undergoing major abdominal surgery

    NARCIS (Netherlands)

    Haverkort, Elizabeth B.; Binnekade, Jan M.; de van der Schueren, Marian A. E.; Gouma, Dirk J.; de Haan, Rob J.

    2015-01-01

    Bioelectrical impedance analysis (BIA) is a method used to estimate body compartments such as fat-free mass (FFM) and fat mass (FM). Two BIA devices, a single-frequency BIA (SF-BIA) device and a bioimpedance spectroscopy (BIS) approach, were compared to evaluate their reliability and to study

  7. Estimation of Body Composition Depends on Applied Device in Patients Undergoing Major Abdominal Surgery

    NARCIS (Netherlands)

    Haverkort, E.B.; Binnekade, J.M.; van Bokhorst-de van der Schueren, M.A.E.; Gouma, D.J.; de Haan, R.J.

    2015-01-01

    Background: Bioelectrical impedance analysis (BIA) is a method used to estimate body compartments such as fat-free mass (FFM) and fat mass (FM). Two BIA devices, a single-frequency BIA (SF-BIA) device and a bioimpedance spectroscopy (BIS) approach, were compared to evaluate their reliability and to

  8. Impedance of accelerator components

    International Nuclear Information System (INIS)

    Corlett, J.N.

    1996-05-01

    As demands for high luminosity and low emittance particle beams increase, an understanding of the electromagnetic interaction of these beams with their vacuum chamber environment becomes more important in order to maintain the quality of the beam. This interaction is described in terms of the wake field in time domain, and the beam impedance in frequency domain. These concepts are introduced, and related quantities such as the loss factor are presented. The broadband Q = 1 resonator impedance model is discussed. Perturbation and coaxial wire methods of measurement of real components are reviewed

  9. Superconducting active impedance converter

    International Nuclear Information System (INIS)

    Ginley, D.S.; Hietala, V.M.; Martens, J.S.

    1993-01-01

    A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductors allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology. 12 figures

  10. Impedance analysis of oxygen reduction in Au nanoparticles; Analisis por impedancia de la reduccion de oxigeno sobre nanoparticulas de Au

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez-Huerta, G.; Ramos-Sanchez, G. [Cinvestav-IPN, Mexico, D.F. (Mexico)]. E-mail: gervazkez@gmail.com; Antano-Lopez, R. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S. C., Pedro Escobedo, Queretaro (Mexico); Solorza-Feria, O. [Cinvestav-IPN, Mexico, D.F. (Mexico)

    2009-09-15

    Nanometric-sized ({approx}5nm) Au particles were synthesized using the chemical reduction of AuCl{sub 3} with NaBH{sub 4}. The Au particles were analyzed with x-ray diffraction (XRD), finding that the particles are highly crystalline, with a face-centered cubic (FCC) structure. The impedance spectrums obtained in 0.5M H{sub 2}SO{sub 4} solution saturated with O{sub 2}, at potentials greater than 0.38 V vs NHE, show one single temperature constant associated with the reduction in O{sub 2} on Au particles, producing hydrogen peroxide (O{sub 2} +2H{sup +} + 2e{sup -} =H{sub 2}O{sub 2}). At potentials less than 0.38 V, a second constant temperature appears associated with a second process, that is, the reduction of H{sub 2}O{sub 2} to H{sub 2}O. [Spanish] Particulas de Au con tamano nanometrico ({approx}5nm) fueron sintetizadas a partir de la reduccion quimica del AuCl{sub 3} con NaBH{sub 4}. Las particulas de Au fueron analizadas con difraccion de rayos X (XRD), se encontro que las particulas son altamente cristalinas, con una estructura cubica centrada en las caras (FCC). Los espectros de impedancia obtenidos en solucion 0.5M H{sub 2}SO{sub 4} saturada con O{sub 2}, a potenciales mayores de 0.38 V vs NHE muestran una sola constante de tiempo, asociada a la reduccion de O{sub 2} sobre las particulas de Au, dando como producto peroxido de hidrogeno (O{sub 2} +2H{sup +} + 2e{sup -} =H{sub 2}O{sub 2}). A potenciales menores de 0.38 V aparece una segunda constante de tiempo, asociada a un segundo proceso, i.e. la reduccion del H{sub 2}O{sub 2} a H{sub 2}O.

  11. BIA and DOD Schools: Student Achievement and Other Characteristics Often Differ from Public Schools

    National Research Council Canada - National Science Library

    2001-01-01

    ...) and the Department of Defense (DOD) school systems. Unlike public schools, where federal funding constitutes a small portion of total resources, the BIA and DOD school systems depend almost entirely on federal funds...

  12. BIA AND DOD SCHOOLS: Student Achievement and Other Characteristics Often Differ from Public Schools

    National Research Council Canada - National Science Library

    2001-01-01

    ...) and the Department of Defense (DOD) school systems. Unlike public schools, where federal funding constitutes a small portion of total resources, the BIA and DOD school systems depend almost entirely on federal funds...

  13. Using open source accelerometer analysis to assess physical activity and sedentary behaviour in overweight and obese adults.

    Science.gov (United States)

    Innerd, Paul; Harrison, Rory; Coulson, Morc

    2018-04-23

    Physical activity and sedentary behaviour are difficult to assess in overweight and obese adults. However, the use of open-source, raw accelerometer data analysis could overcome this. This study compared raw accelerometer and questionnaire-assessed moderate-to-vigorous physical activity (MVPA), walking and sedentary behaviour in normal, overweight and obese adults, and determined the effect of using different methods to categorise overweight and obesity, namely body mass index (BMI), bioelectrical impedance analysis (BIA) and waist-to-hip ratio (WHR). One hundred twenty adults, aged 24-60 years, wore a raw, tri-axial accelerometer (Actigraph GT3X+), for 3 days and completed a physical activity questionnaire (IPAQ-S). We used open-source accelerometer analyses to estimate MVPA, walking and sedentary behaviour from a single raw accelerometer signal. Accelerometer and questionnaire-assessed measures were compared in normal, overweight and obese adults categorised using BMI, BIA and WHR. Relationships between accelerometer and questionnaire-assessed MVPA (Rs = 0.30 to 0.48) and walking (Rs = 0.43 to 0.58) were stronger in normal and overweight groups whilst sedentary behaviour were modest (Rs = 0.22 to 0.38) in normal, overweight and obese groups. The use of WHR resulted in stronger agreement between the questionnaire and accelerometer than BMI and BIA. Finally, accelerometer data showed stronger associations with BMI, BIA and WHR (Rs = 0.40 to 0.77) than questionnaire data (Rs = 0.24 to 0.37). Open-source, raw accelerometer data analysis can be used to estimate MVPA, walking and sedentary behaviour from a single acceleration signal in normal, overweight and obese adults. Our data supports the use of WHR to categorise overweight and obese adults. This evidence helps researchers obtain more accurate measures of physical activity and sedentary behaviour in overweight and obese populations.

  14. Impedance spectroscopic and dielectric analysis of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rouahi, A. [Grenoble Electrical Engineering Laboratory (G2E Lab), CNRS, University of Grenoble (UJF), 25 Rue des Martyrs, BP 166, 38042 Grenoble Cedex 9 (France); Laboratory of Materials, Organization and Properties (LMOP), Campus Universities, El Manar, 2092 Tunis (Tunisia); Kahouli, A., E-mail: kahouli.kader@yahoo.fr [Grenoble Electrical Engineering Laboratory (G2E Lab), CNRS, University of Grenoble (UJF), 25 Rue des Martyrs, BP 166, 38042 Grenoble Cedex 9 (France); Laboratory of Materials, Organization and Properties (LMOP), Campus Universities, El Manar, 2092 Tunis (Tunisia); Sylvestre, A., E-mail: alain.sylvestre@grenoble.cnrs.fr [Grenoble Electrical Engineering Laboratory (G2E Lab), CNRS, University of Grenoble (UJF), 25 Rue des Martyrs, BP 166, 38042 Grenoble Cedex 9 (France); Defaye, E. [CEA-LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Yangui, B. [Laboratory of Materials, Organization and Properties (LMOP), Campus Universities, El Manar, 2092 Tunis (Tunisia)

    2012-07-15

    Highlights: Black-Right-Pointing-Pointer The material exhibits the contribution of both grain and grain boundaries in the electric response of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3}. Black-Right-Pointing-Pointer The plot of normalized complex dielectric modulus and impedance as a function of frequency exhibits both short and long-range conduction in the film. Black-Right-Pointing-Pointer The frequency dependence of ac conductivity exhibits a polaron hopping mechanism with activation energy of 0.38 eV. Black-Right-Pointing-Pointer The complex dielectric modulus analysis confirmed the presence of a non-Debye type of conductivity relaxation deduced from the KWW function. - Abstract: Polycrystalline Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} thin film with Pt/BST/Pt/TiO{sub 2}/SiO{sub 2} structure was prepared by ion beam sputtering. The film was post annealed at 700 Degree-Sign C. The dielectric and electric modulus properties were studied by impedance spectroscopy over a wide frequency range [0.1-10{sup 5} Hz] at different temperatures [175-350 Degree-Sign C]. The Nyquist plots (Z Double-Prime vs . Z Prime ) show the contribution of both grain and grain boundaries at higher temperature on the electric response of BST thin films. Moreover, the resistance of grains decreases with the rise in temperature and the material exhibits a negative temperature coefficient of resistance. The electric modulus plot indicates the non-Debye type of dielectric relaxation. The values of the activation energy computed from both plots of Z Double-Prime and M Double-Prime are 0.86 eV and 0.81 eV respectively, which reveals that the species responsible for conduction are the same. The scaling behavior of M{sup Double-Prime }/M{sup Double-Prime }{sub max} shows the temperature independent nature of relaxation time. The plot of normalized complex dielectric modulus and impedance as a function of frequency exhibits both short and long-range conduction in the film.

  15. 22 Cases of BIA-ALCL: Awareness and Outcome Tracking from the Italian Ministry of Health.

    Science.gov (United States)

    Antonella, Campanale; Rosaria, Boldrini; Marcella, Marletta

    2017-09-13

    To date, 359 cases of anaplastic large cell lymphoma in women with breast implants (BIA-ALCL) worldwide have been reported out of more than 10 million implanted patients but Health Care Authorities suspect this is a possible underestimation and the limited number of cases makes it difficult to clarify its etiology. The General Directorate of Medical Devices and Pharmaceutical Services of the Italian Ministry of Health (IMoH) has examined and studied the Italian BIA-ALCL cases, and the aim of this study is to report on the knowledge and experience gained on this new emerging disease. An official document has been diffused by the IMoH to all the Italian medical associations, aiming at encouraging all physicians to notify each BIA-ALCL case through the compilation of a specific on-line form. A retrospective study has been performed on the notified BIA-ALCL cases collected in the IMoH's database named DISPOVIGILANCE. Research on DISPOVIGILANCE gives back a list of 22 Italian BIA-ALCL cases. The patients' mean age was 49.6 years (range 30 -71). The average time to the onset of the symptoms was 6.8 years (range 1-22). The average time to the diagnosis was 7.8 years (range 4 -22). The estimated incidence of the Italian BIA-ALCL cases related to 2015 is 2.8 per 100.000 patients. The BIA-ALCL pathogenesis remains unknown. The Italian Ministry of Health, together with scientific associations and other Competent Authorities worldwide, is working on the BIA-ALCL issue to increase awareness and knowledge of this disease by healthcare professionals.

  16. Książka o getcie białostockim

    DEFF Research Database (Denmark)

    Kerszman, Gustaw

    2014-01-01

    Remarks about the book: Rafael Rajzner, Henry R. Lew: Losy nieopowiedziane. Zagłada Żydów białostockich 1939-1945 (Żydowski Instytut Historyczny im. E. Ringelbluma : Warszawa 2013)......Remarks about the book: Rafael Rajzner, Henry R. Lew: Losy nieopowiedziane. Zagłada Żydów białostockich 1939-1945 (Żydowski Instytut Historyczny im. E. Ringelbluma : Warszawa 2013)...

  17. Dielectric, ferroelectrics properties and impedance spectroscopy analysis of the [(Na0.535K0.4800.966Li0.058](Nb0.90Ta0.10O3-based lead-free ceramics

    Directory of Open Access Journals (Sweden)

    M. Saidi

    2015-03-01

    Full Text Available Polycrystalline of [(Na0.535K0.4800.966Li0.058](Nb0.90Ta0.10O3 samples were prepared using the high-temperature solid-state reaction technique. X-ray diffraction (XRD analysis indicates the formation of a single-phase with orthorhombic structure. AC impedance plots were used as tool to analyze the electrical behavior of the sample as a function of frequency at different temperatures. The AC impedance studies revealed the presence of grain effect, from 425°C onwards. Complex impedance analysis indicated non-Debye type dielectric relaxation. The Nyquist plot showed the negative temperature coefficient of resistance (NTCR characteristic of NKLNT. The AC conductivity results were used to correlate with the barrier hopping (CBH model to evaluate the binding energy (Wm, the minimum hopping distance (Rmin, the density of states at Fermi level (N(Ef, and the activation energy of the compound.

  18. Body composition analysis and adipocytokine concentrations in haemodialysis patients: abdominal fat gain as an additional cardiovascular risk factor.

    Science.gov (United States)

    González, Elena; Díez, Juan J; Pérez Torres, Almudena; Bajo, María Auxiliadora; Del Peso, Gloria; Sánchez-Villanueva, Rafael; Grande, Cristina; Rodríguez, Olaia; Coronado, Mónica; Gómez Candela, Carmen; Díaz-Almirón, Mariana; Iglesias, Pedro; Selgas, Rafael

    Abdominal fat and its increment over time in particular has become a cardiovascular risk factor in uraemic patients. To analyse changes in abdominal fat in haemodialysis patients over one year and study their possible correlation with the variation in adipocytokine serum levels. As a secondary objective, we tried to validate the data obtained by bioelectrical impedance analysis (BIA) with data obtained by dual X-ray absorptiometry (DXA). A prospective one-year study was performed in 18 patients on haemodialysis (HD). In each patient, body composition by BIA and DXA was estimated at baseline and after one year. Several adipocytokine and biochemical parameters were determined. A significant increase in phase angle [4.8° (4.1-5.6) vs. 5.2° (4.4-5.8), Pfat measured by DXA [1.00 (0.80-1.26) vs. 1.02 (0.91-1.30), Pfat mass measured by BIA, as well as the abdominal fat percentage estimated by DXA, was found (Pfat mass over time, especially in the abdomen, evidenced by an increased A/G ratio. These findings might explain the increased cardiovascular risk in these patients. Copyright © 2016 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.

  19. Impedance and electric modulus analysis of Sm-modified Pb(Zr{sub 0.55}Ti{sub 0.45}){sub 1-x/4}O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ranjan, Rajiv [Department of Physics, J. Co-operative College, Kolhan University, Jharkhand 831036 (India); Kumar, Rajiv [Department of Physics, J. Worker' s College, Kolhan University, Jharkhand 831012 (India); Kumar, Nawnit [Department of Physics and Meteorology, IIT Kharagpur, West Bengal 721302 (India); Behera, Banarji [School of Physics, Sambalpur University, Jyoti Vihar, Bula 768019, Orissa (India); Choudhary, R.N.P., E-mail: crnpfl@gmail.com [Department of Physics, ITER, S.O.A. University, Bhubaneswar 751 013, Orissa (India)

    2011-06-02

    Highlights: > The PSZT ceramics with samarium were prepared by solid-state reaction technique. > Bulk resistive contribution is found to decrease with the increase in temperature. > PSZT ceramics exhibit NTCR type behavior usually found in semiconductors. > Modulus plots show the presence of grain boundary along with bulk contributions. > Impedance analysis has confirmed the presence of non-Debye type of relaxation. - Abstract: The polycrystalline ceramic samples of Pb{sub 1-x}Sm{sub x}(Zr{sub 0.55}Ti{sub 0.45}){sub 1-x/4}O{sub 3} (x = 0.00, 0.03, 0.06 and 0.09) were prepared by solid-state reaction technique at high temperature. Electric impedance (Z) and modulus (M) properties of the materials have been investigated within a wide range of temperature and frequency using complex impedance spectroscopy (CIS) technique. The complex impedance analysis has suggested the presence of mostly bulk resistive (grain) contributions in the materials. This bulk resistance is found to decrease with the increase in temperature. It indicates that the PSZT compounds exhibit a typical negative temperature coefficient of resistance (NTCR) behavior. The bulk contribution also exhibits an increasing trend with the increase in Sm{sup 3+} substitution to PZT. The complex modulus plots have confirmed the presence of grain (bulk) as well as grain boundary contributions in the materials. Both the complex impedance and modulus studies have suggested the presence of non-Debye type of relaxation in the materials.

  20. Ratio of muscle mass to fat mass assessed by bioelectrical impedance analysis is significantly correlated with liver fat accumulation in patients with type 2 diabetes mellitus.

    Science.gov (United States)

    Kurinami, Noboru; Sugiyama, Seigo; Morita, Ayami; Yoshida, Akira; Hieshima, Kunio; Miyamoto, Fumio; Kajiwara, Keizo; Jinnouch, Katsunori; Jinnouchi, Tomio; Jinnouchi, Hideaki

    2018-05-01

    Obesity and ectopic fat accumulation are important conditions of type 2 diabetes mellitus (T2DM). Our aim was to determine whether bioelectrical impedance body composition analysis combined with blood test results could estimate liver ectopic fat accumulation in patients with treatment-naïve T2DM. Subjects were 119 untreated T2DM patients. Computed tomography scans were performed to calculate the liver to spleen attenuation ratio (L/S ratio) as a measure of liver fat accumulation, with excess liver fat accumulation defined as an L/S ratio analysis using InBody770. The Nagelkerke R 2 test showed that the muscle mass/fat mass ratio (muscle/fat ratio) was the most suitable variable among anthropometric factors and body component indexes for estimating liver fat accumulation. The muscle/fat ratio was significantly correlated with the L/S ratio (ρ = 0.4386, P analysis showed that the muscle/fat ratio (odds ratio 0.40, 95% confidence interval 0.22-0.73, P ratio 1.06, 95% confidence interval 1.02-1.10, P analysis, the cutoff value of the muscle/fat ratio for excess liver fat accumulation was 2.34. In patients with treatment-naïve T2DM, the muscle/fat ratio and ALT are useful for estimating the presence of excess liver fat accumulation in daily clinical practice. Copyright © 2018. Published by Elsevier B.V.

  1. Tapping mode microwave impedance microscopy

    KAUST Repository

    Lai, K.; Kundhikanjana, W.; Peng, H.; Cui, Y.; Kelly, M. A.; Shen, Z. X.

    2009-01-01

    We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately

  2. SSC kicker impedances

    International Nuclear Information System (INIS)

    Colton, E.P.; Wang, T.F.

    1985-01-01

    The longitudinal and transverse complex impedances Z/sub l//n and Z/sub t/, respectively, have been calculated for both the SSC injection and abort kickers. The calculations assumed that no attempt was made to shield the beam from the kickers. We took the injection and abort kickers to be as specified. The injection kickers were ferrite with a single-turn design, and the abort kickers were of a ''window-frame design'' with tape wound cores

  3. A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Galigekere, Veda Prakash

    2016-01-01

    A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance S...

  4. Acoustic impedances of ear canals measured by impedance tube

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2007-01-01

    During hearing sensitivity tests, the sound field is commonly generated by an earphone placed on a subject ear. One of the factors that can affect the sound transmission in the ear is the acoustic impedance of the ear canal. Its importance is related to the contribution of other elements involved...... in the transmission such as the earphone impedance. In order to determine the acoustic impedances of human ear canals, the standardized method for measurement of complex impedances used for the measurement of the audiometric earphone impedances is applied. It is based on the transfer function between two microphone...... locations in an impedance tube. The end of the tube representing the measurement plane is placed at the ear canal entrance. Thus, the impedance seen from the entrance inward is measured on 25 subjects. Most subjects participated in the previous measurement of the ratio between the pressures at the open...

  5. Chest electrical impedance tomography examination, data analysis, terminology, clinical use and recommendations: Consensus statement of the TRanslational EIT developmeNt stuDy group

    NARCIS (Netherlands)

    Frerichs, I. (Inéz); M.B.P. Amato (Marcelo); A.H. van Kaam (Anton); Tingay, D.G. (David G.); Zhao, Z. (Zhanqi); Grychtol, B. (Bartlomiej); Bodenstein, M. (Marc); Gagnon, H. (Hervé); S.H. Bohm; Teschner, E. (Eckhard); O. Stenqvist (Ola); Mauri, T. (Tommaso); Torsani, V. (Vinicius); Camporota, L. (Luigi); Schibler, A. (Andreas); Wolf, G.K. (Gerhard K.); D.A.M.P.J. Gommers (Diederik); S. Leonhardt (Steffen); Adler, A. (Andy); Fan, E. (Eddy); Lionheart, W.R.B. (William R.B.); Riedel, T. (Thomas); Rimensberger, P.C. (Peter C.); Suarez, F. (Fernando); Weiler, S.N. (Sipmann Norbert); H. Wrigge (Hermann)

    2017-01-01

    textabstractElectrical impedance tomography (EIT) has undergone 30 years of development. Functional chest examinations with this technology are considered clinically relevant, especially for monitoring regional lung ventilation in mechanically ventilated patients and for regional pulmonary function

  6. Chest electrical impedance tomography examination, data analysis, terminology, clinical use and recommendations: Consensus statement of the TRanslational EIT developmeNt stuDy group

    NARCIS (Netherlands)

    Frerichs, I. (Inéz); M.B.P. Amato (Marcelo); A.H. van Kaam (Anton); Tingay, D.G. (David G.); Zhao, Z. (Zhanqi); Grychtol, B. (Bartlomiej); Bodenstein, M. (Marc); Gagnon, H. (Hervé); S.H. Bohm; Teschner, E. (Eckhard); O. Stenqvist (Ola); Mauri, T. (Tommaso); Torsani, V. (Vinicius); Camporota, L. (Luigi); Schibler, A. (Andreas); Wolf, G.K. (Gerhard K.); D.A.M.P.J. Gommers (Diederik); S. Leonhardt (Steffen); Adler, A. (Andy); Fan, E. (Eddy); Lionheart, W.R.B. (William R.B.); Riedel, T. (Thomas); Rimensberger, P.C. (Peter C.); Sipmann, F.S. (Fernando Suarez); Weiler, N. (Norbert); H. Wrigge (Hermann)

    2016-01-01

    textabstractElectrical impedance tomography (EIT) has undergone 30 years of development. Functional chest examinations with this technology are considered clinically relevant, especially for monitoring regional lung ventilation in mechanically ventilated patients and for regional pulmonary function

  7. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J S [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)

  8. X-ray photoelectron spectroscopic and electrochemical impedance spectroscopic analysis of RuO_2-Ta_2O_5 thick film pH sensors

    International Nuclear Information System (INIS)

    Manjakkal, Libu; Cvejin, Katarina; Kulawik, Jan; Zaraska, Krzysztof; Socha, Robert P.; Szwagierczak, Dorota

    2016-01-01

    The paper reports on investigation of the pH sensing mechanism of thick film RuO_2-Ta_2O_5 sensors by using X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Interdigitated conductimetric pH sensors were screen printed on alumina substrates. The microstructure and elemental composition of the films were examined by scanning electron microscopy and energy dispersive spectroscopy. The XPS studies revealed the presence of Ru ions at different oxidation states and the surface hydroxylation of the sensing layer increasing with increasing pH. The EIS analysis carried out in the frequency range 10 Hz–2 MHz showed that the electrical parameters of the sensitive electrodes in the low frequency range were distinctly dependent on pH. The charge transfer and ionic exchange occurring at metal oxide-solution interface were indicated as processes responsible for the sensing mechanism of thick film RuO_2-Ta_2O_5 pH sensors. - Highlights: • Conductimetric pH sensors with RuO_2-Ta_2O_5 thick film electrodes were developed. • Microstructure and elemental composition of the films were examined by SEM and EDX. • Sensing film composition and hydroxylation were studied by XPS as a function of pH. • Electrochemical reactions at oxide-solution interface were analyzed by EIS method. • Impact of solution pH, electrode composition and sintering temperature was studied.

  9. Chest electrical impedance tomography examination, data analysis, terminology, clinical use and recommendations: consensus statement of the TRanslational EIT developmeNt stuDy group.

    Science.gov (United States)

    Frerichs, Inéz; Amato, Marcelo B P; van Kaam, Anton H; Tingay, David G; Zhao, Zhanqi; Grychtol, Bartłomiej; Bodenstein, Marc; Gagnon, Hervé; Böhm, Stephan H; Teschner, Eckhard; Stenqvist, Ola; Mauri, Tommaso; Torsani, Vinicius; Camporota, Luigi; Schibler, Andreas; Wolf, Gerhard K; Gommers, Diederik; Leonhardt, Steffen; Adler, Andy

    2017-01-01

    Electrical impedance tomography (EIT) has undergone 30 years of development. Functional chest examinations with this technology are considered clinically relevant, especially for monitoring regional lung ventilation in mechanically ventilated patients and for regional pulmonary function testing in patients with chronic lung diseases. As EIT becomes an established medical technology, it requires consensus examination, nomenclature, data analysis and interpretation schemes. Such consensus is needed to compare, understand and reproduce study findings from and among different research groups, to enable large clinical trials and, ultimately, routine clinical use. Recommendations of how EIT findings can be applied to generate diagnoses and impact clinical decision-making and therapy planning are required. This consensus paper was prepared by an international working group, collaborating on the clinical promotion of EIT called TRanslational EIT developmeNt stuDy group. It addresses the stated needs by providing (1) a new classification of core processes involved in chest EIT examinations and data analysis, (2) focus on clinical applications with structured reviews and outlooks (separately for adult and neonatal/paediatric patients), (3) a structured framework to categorise and understand the relationships among analysis approaches and their clinical roles, (4) consensus, unified terminology with clinical user-friendly definitions and explanations, (5) a review of all major work in thoracic EIT and (6) recommendations for future development (193 pages of online supplements systematically linked with the chief sections of the main document). We expect this information to be useful for clinicians and researchers working with EIT, as well as for industry producers of this technology. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  10. A Systematic Content Analysis of Policy Barriers Impeding Access to Opioid Medication in Central and Eastern Europe: Results of ATOME.

    Science.gov (United States)

    Larjow, Eugenia; Papavasiliou, Evangelia; Payne, Sheila; Scholten, Willem; Radbruch, Lukas

    2016-01-01

    Reliable access to opioid medication is critical to delivering effective pain management, adequate treatment of opioid dependence, and quality palliative care. However, more than 80% of the world population is estimated to be inadequately treated for pain because of difficulties in accessing opioids. Although barriers to opioid access are primarily associated with restrictive laws, regulations, and licensing requirements, a key problem that significantly limits opioid access relates to policy constraints. To identify and explore policy barriers to opioid access in 12 Eastern and Central European countries involved in the Access to Opioid Medication in Europe project, funded by the European Community's Seventh Framework (FP7/2007-2013, no. 222994) Programme. A systematic content analysis of texts retrieved from documents (e.g., protocols of national problem analyses, strategic planning worksheets, and executive summaries) compiled, reviewed, approved, and submitted by either the Access to Opioid Medication in Europe consortium or the national country teams (comprising experts in pain management, harm reduction, and palliative care) between September 2011 and April 2014 was performed. Twenty-five policy barriers were identified (e.g., economic crisis, bureaucratic issues, lack of training initiatives, stigma, and discrimination), classified under four predetermined categories (financial/economic aspects and governmental support, formularies, education and training, and societal attitudes). Key barriers related to issues of funding allocation, affordability, knowledge, and fears associated with opioids. Reducing barriers and improving access to opioids require policy reform at the governmental level with a set of action plans being formulated and concurrently implemented and aimed at different levels of social, education, and economic policy change. Copyright © 2016 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

  11. Análise clínica e biomecânica do efeito do diclofenaco sódico na consolidação da fratura da tíbia no rato Clinical and biomechanical analysis of the effect of diclofenac sodium in tibial fracture healing in rats

    Directory of Open Access Journals (Sweden)

    Sérgio Swain Müller

    2004-12-01

    Full Text Available Os AINH (Antiinflamatórios não hormonais são agentes utilizados na prática clínica que interferem no processo inflamatório pela inibição da síntese de prostaglandinas e tromboxanos. Alguns trabalhos experimentais investigaram sua ação no processo de consolidação de fraturas, por meio de estudos clínicos e histológicos, sendo escassas as análises biomecânicas. Nesse estudo foram utilizados 20 ratos da linhagem Wistar, divididos aleatoriamente em dois grupos iguais: grupo A (controle e grupo B (tratado com diclofenaco sódico. Em ambos os grupos foram realizadas fraturas abertas, após perfuração, na tíbia direita. A administração da droga foi via intramuscular, dose única diária, por 28 dias. Os animais foram pesados semanalmente. Após o sacrifício as tíbias foram dissecadas, pesadas e submetidas a ensaio biomecânico de flexão analisando-se carga máxima, deformação e coeficiente de rigidez. Observou-se que no grupo tratado com AINH não houve aumento do peso corpóreo a partir da segunda semana e as tíbias fraturadas foram mais pesadas. Neste grupo o calo ósseo suportou menor carga máxima, apresentando maior deformação e menor coeficiente de rigidez. Nos animais tratados, o osso não fraturado também se mostrou menos rígido. Concluiu-se, nas condições estudadas, que o DS alterou o processo de consolidação e o metabolismo ósseo, levando a retardo na maturação do calo e menor rigidez do osso intacto, respectivamente.The antinflammatories are agents utilized on clinical practice that interfere on inflammatory process by synthesis inhibition of prostaglandin and tromboxanes. Some experimental studies investigated their action on the fractures consolidation process, through clinical and histological studies, as the biomechanical analyses are scarce. In this study, 20 (twenty Wistar pedigree rats were used, aleatory divided into two groups: A group (control and B group (treated with diclofenac. In both

  12. LIA longitudinal coupling impedance

    International Nuclear Information System (INIS)

    Faltens, A.

    1980-01-01

    The beam generated fields enter into the problems of waveform generation and longitudinal stability. In the former, provision must be made for the longitudinally defocusing forces due to the space charge and the beam loading effects on the accelerating voltage due to the current of a presumably known bunch. In the latter, the concern is for the growth of unintentional perturbations to unacceptably large values through the interaction of the charge and current fluctuations with the rest of the beam and the surrounding structures. These beam generated electric fields may be related to the beam current through a coupling impedance

  13. RF impedance measurement calibration

    International Nuclear Information System (INIS)

    Matthews, P.J.; Song, J.J.

    1993-01-01

    The intent of this note is not to explain all of the available calibration methods in detail. Instead, we will focus on the calibration methods of interest for RF impedance coupling measurements and attempt to explain: (1). The standards and measurements necessary for the various calibration techniques. (2). The advantages and disadvantages of each technique. (3). The mathematical manipulations that need to be applied to the measured standards and devices. (4). An outline of the steps needed for writing a calibration routine that operated from a remote computer. For further details of the various techniques presented in this note, the reader should consult the references

  14. 25 CFR Appendix A to Subpart G - List of Activities Eligible for Funding Under BIA Transportation Facility Maintenance Program

    Science.gov (United States)

    2010-04-01

    ... Transportation Facility Maintenance Program A Appendix A to Subpart G Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER INDIAN RESERVATION ROADS PROGRAM BIA Road Maintenance Pt. 170... Transportation Facility Maintenance Program The following activities are eligible for BIA Transportation Facility...

  15. 25 CFR 170.807 - What must BIA include when it develops an IRR Transportation Facilities Maintenance Management...

    Science.gov (United States)

    2010-04-01

    ... Transportation Facilities Maintenance Management System? 170.807 Section 170.807 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER INDIAN RESERVATION ROADS PROGRAM BIA Road Maintenance § 170.807 What must BIA include when it develops an IRR Transportation Facilities Maintenance Management System...

  16. 25 CFR 103.39 - When will BIA refuse to pay all or part of a lender's claim?

    Science.gov (United States)

    2010-04-01

    ... to liquidate loan collateral, and: (1) The lender has not made a reasonable effort to liquidate all... from collateral liquidation proceeds applied to the loan balance; or (e) The lender has otherwise... ACTIVITIES LOAN GUARANTY, INSURANCE, AND INTEREST SUBSIDY Default and Payment by BIA § 103.39 When will BIA...

  17. 25 CFR 171.420 - Can I dispose of sewage, trash, or other refuse on a BIA irrigation project?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Can I dispose of sewage, trash, or other refuse on a BIA... AND WATER IRRIGATION OPERATION AND MAINTENANCE Irrigation Facilities § 171.420 Can I dispose of sewage, trash, or other refuse on a BIA irrigation project? No. Sewage, trash, or other refuse are considered...

  18. Electrical impedance tomography

    Science.gov (United States)

    Lobo, Beatriz; Hermosa, Cecilia; Abella, Ana

    2018-01-01

    Continuous assessment of respiratory status is one of the cornerstones of modern intensive care unit (ICU) monitoring systems. Electrical impedance tomography (EIT), although with some constraints, may play the lead as a new diagnostic and guiding tool for an adequate optimization of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and of end-expiratory lung volume (EELV) and contribute to titrate positive end-expiratory pressure (PEEP)/tidal volume combinations. It may also quantify gains (recruitment) and losses (overdistention or derecruitment), granting a more realistic evaluation of different ventilator modes or recruitment maneuvers, and helping in the identification of responders and non-responders to such maneuvers. Moreover, EIT also contributes to the management of life-threatening lung diseases such as pneumothorax, and aids in guiding fluid management in the critical care setting. Lastly, assessment of cardiac function and lung perfusion through electrical impedance is on the way. PMID:29430443

  19. 25 CFR 115.422 - As a custodial parent, the legal guardian, the person who BIA has recognized as having control...

    Science.gov (United States)

    2010-04-01

    ... BIA has recognized as having control and custody of the minor, or an emancipated minor, what are your... BIA has recognized as having control and custody of the minor, or an emancipated minor, what are your... legal guardian, the person who BIA has recognized as having control and custody of the minor, or an...

  20. Impedance Spectroscopy of Dielectrics and Electronic Conductors

    DEFF Research Database (Denmark)

    Bonanos, Nikolaos; Pissis, Polycarpos; Macdonald, J. Ross

    2013-01-01

    Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property, such as admi......Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property......, such as admittance or dielectric constant - as a function of frequency and comparing the results with expectations based on physical, chemical, and microstructural models. This article reviews the principles and practical aspects of the technique, the representations of the results, the analysis of data......, and procedures for the correction of measurement errors. The applications of impedance spectroscopy are illustrated with examples from electroceramics and polymer-based dielectric systems. The way in which the technique is applied to the two classes of materials is compared with reference to the different models...

  1. Impedance of the PEP-II DIP screen

    Energy Technology Data Exchange (ETDEWEB)

    Ng, C -K [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Weiland, T

    1996-08-01

    The vacuum chamber of a storage ring normally consists of periodically spaced pumping slots. The longitudinal impedance of slots are analyzed in this paper. It is found that although the broad-band impedance is tolerable, the narrow-band impedance, as a consequence of the periodicity of the slots, may exceed the stability limit given by natural damping with no feedback system on. Based on this analysis, the PEP-II distributed-ion-pump (DIP) screen uses long grooves with hidden holes cut halfway to reduce both the broad-band and narrow-band impedances. (author)

  2. Impedance of the PEP-II DIP screen

    International Nuclear Information System (INIS)

    Ng, C.K.; Weiland, T.

    1995-09-01

    The vacuum chamber of a storage ring normally consists of periodically spaced pumping slots. The longitudinal impedance of slots are analyzed in this paper. It is found that although the broad-band impedance is tolerable, the narrow-band impedance, as a consequence of the periodicity of the slots, may exceed the stability limit given by natural damping with no feedback system on. Based on this analysis, the PEP-II distributed-ion-pump (DIP) screen uses long grooves with hidden holes cut halfway to reduce both the broad-band and narrow-band impedances

  3. Microwave Impedance Measurement for Nanoelectronics

    Directory of Open Access Journals (Sweden)

    M. Randus

    2011-04-01

    Full Text Available The rapid progress in nanoelectronics showed an urgent need for microwave measurement of impedances extremely different from the 50Ω reference impedance of measurement instruments. In commonly used methods input impedance or admittance of a device under test (DUT is derived from measured value of its reflection coefficient causing serious accuracy problems for very high and very low impedances due to insufficient sensitivity of the reflection coefficient to impedance of the DUT. This paper brings theoretical description and experimental verification of a method developed especially for measurement of extreme impedances. The method can significantly improve measurement sensitivity and reduce errors caused by the VNA. It is based on subtraction (or addition of a reference reflection coefficient and the reflection coefficient of the DUT by a passive network, amplifying the resulting signal by an amplifier and measuring the amplified signal as a transmission coefficient by a common vector network analyzer (VNA. A suitable calibration technique is also presented.

  4. Literatura białoruska w Polsce po roku 1989. O potrzebie tworzenia bazy literackiej

    Directory of Open Access Journals (Sweden)

    Grażyna Charytoniuk-Michiej

    2014-12-01

    Full Text Available Belarusian literature in Poland after 1989. About the necessity of developing a literature database Speaking about Belarusian literature in Poland we focus on fiction, its translation into Polish and the study of literature. The existence of the Belarusian literature in Poland in the post-war period is indicated by the following bibliographies: a bibliography of translations for the period 1945–1994 (G. Charytoniuk, Literatura białoruska w Polsce. Bibliografia przekładów za lata 1945–1994, Białystok 1996 and a subject bibliography for the period 1945–1998 (G. Charytoniuk, Polskie białorutenika literackie. Bibliografia przedmiotowa 1945–1998, Białystok 1998. The new political, economical and social conditions in Poland after 1989 have had an influence on the situation of the Belarusian literature. In addition to the existing departments some new university departments and scientific branches have been organized. Their aim is to realize new scientific projects connected with the Belarusian literature in Poland and Belarus. A lot of nongovernment organizations (funds, partnerships, associations have been organized not only in Bialystok region, but also in the other parts of the country. A new publishing market has been established which has focused on the modern literature of Central and Eastern Europe including Belarusian literature. The Internet also plays an important role in popularization of the Belarusian literature. That literature has been included in the database of the National library (Przewodnik Bibliograficzny, Bibliografia Zawartości Czasopism, regional libraries (Bibliografia województwa podlaskiego and the digital library (Polska Bibliografia Literacka. The information is searched by institutional scientific depositories and digital libraries. The considerable part of the information has not been registered in the bibliographic database. In this situation it is necessary to develop an integral literature

  5. NOTE: Impedance magnetocardiogram

    Science.gov (United States)

    Kandori, Akihiko; Miyashita, Tsuyoshi; Suzuki, Daisuke; Yokosawa, Koichi; Tsukada, Keiji

    2001-02-01

    We have developed an impedance magnetocardiogram (IMCG) system to detect the change of magnetic field corresponding to changes in blood volume in the heart. A low magnetic field from the electrical activity of the human heart - the so-called magnetocardiogram (MCG) - can be simultaneously detected by using this system. Because the mechanical and electrical functions in the heart can be monitored by non-invasive and non-contact measurements, it is easy to observe the cardiovascular functions from an accurate sensor position. This system uses a technique to demodulate induced current in a subject. A flux-locked circuit of a superconducting quantum interference device has a wide frequency range (above 1 MHz) because a constant current (40 kHz) is fed through the subject. It is shown for the first time that the system could measure IMCG signals at the same time as MCG signals.

  6. Synthesis of adaptive impedance control for bipedal robot mechanisms

    OpenAIRE

    Petrović Milena; Rodić Aleksandar

    2008-01-01

    The paper describes the impedance algorithm in locomotion of humanoid robot with proposed parameter modulation depending on the gate phase. The analysis shows influence of walking speed and foot elevation on regulator's parameters. Chosen criterion cares for footpath tracking and needed energy for that way of walking. The experiments give recommendation for impedance regulator tuning.

  7. Bioelectrical impedance and visceral fat: a comparison with computed tomography in adults and elderly; Bioimpedancia eletrica e gordura visceral: uma comparacao com a tomografia computadorizada em adultos e idosos

    Energy Technology Data Exchange (ETDEWEB)

    Eickemberg, Michaela [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Roriz, Anna Karla Carneiro [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Fontes, Gardenia Abreu Vieira [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Sampaio, Lilian Ramos [Universidade Federal de Sao Paulo (Unifesp), Sao Paulo, SP (Brazil)

    2013-05-01

    Objective: To evaluate the association between electrical bioimpedance analysis (BIA) and visceral fat (VF) in adult and elderly patients. Subjects and methods: This was a cross-sectional study, with a sample of 191 subjects (52% women, 49% elderly) stratified by sex, age and body mass. Computerized tomography (VF area) and BIA (percentage of total body fat (%TBF-BIA), phase angle, reactance and resistance) data were generated. Statistical analysis was based on Pearson's Correlation Coefficient, Anova, Pearson's Chi-square, and ROC curves. Results: VF areas {>=} 130 cm{sup 2} were more prevalent among the elderly and among men. Adult females showed a stronger correlation between GV and %TBF-BIA. The other groups showed similar results and statistically significant correlations. Correlations between GV and phase angle were weak and not statistically significant. ROC Curves analyzes showed the following %TBF-BIA, which identified excess VF: for male subjects: 21.5% (adults) and 24.25% (elderly); for female subjects: 35.05% (adults) and 38.45% (elderly) with sensitivity of 78.6%, 82.1%, 83.3%, and 66.7%, and specificity of 70.6%, 62.5%, 79.1%, and 69%, respectively. Conclusion: BIA was found to have satisfactory sensitivity and specificity to predict VF; however, other devices and other techniques should be investigated to improve VF prediction. (author)

  8. Bioelectrical impedance and visceral fat: a comparison with computed tomography in adults and elderly; Bioimpedancia eletrica e gordura visceral: uma comparacao com a tomografia computadorizada em adultos e idosos

    Energy Technology Data Exchange (ETDEWEB)

    Eickemberg, Michaela [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Roriz, Anna Karla Carneiro [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Fontes, Gardenia Abreu Vieira [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Sampaio, Lilian Ramos [Universidade Federal de Sao Paulo (Unifesp), Sao Paulo, SP (Brazil)

    2013-05-01

    Objective: To evaluate the association between electrical bioimpedance analysis (BIA) and visceral fat (VF) in adult and elderly patients. Subjects and methods: This was a cross-sectional study, with a sample of 191 subjects (52% women, 49% elderly) stratified by sex, age and body mass. Computerized tomography (VF area) and BIA (percentage of total body fat (%TBF-BIA), phase angle, reactance and resistance) data were generated. Statistical analysis was based on Pearson's Correlation Coefficient, Anova, Pearson's Chi-square, and ROC curves. Results: VF areas {>=} 130 cm{sup 2} were more prevalent among the elderly and among men. Adult females showed a stronger correlation between GV and %TBF-BIA. The other groups showed similar results and statistically significant correlations. Correlations between GV and phase angle were weak and not statistically significant. ROC Curves analyzes showed the following %TBF-BIA, which identified excess VF: for male subjects: 21.5% (adults) and 24.25% (elderly); for female subjects: 35.05% (adults) and 38.45% (elderly) with sensitivity of 78.6%, 82.1%, 83.3%, and 66.7%, and specificity of 70.6%, 62.5%, 79.1%, and 69%, respectively. Conclusion: BIA was found to have satisfactory sensitivity and specificity to predict VF; however, other devices and other techniques should be investigated to improve VF prediction. (author)

  9. Isocratic and gradient impedance plot analysis and comparison of some recently introduced large size core-shell and fully porous particles.

    Science.gov (United States)

    Vanderheyden, Yoachim; Cabooter, Deirdre; Desmet, Gert; Broeckhoven, Ken

    2013-10-18

    The intrinsic kinetic performance of three recently commercialized large size (≥4μm) core-shell particles packed in columns with different lengths has been measured and compared with that of standard fully porous particles of similar and smaller size (5 and 3.5μm, respectively). The kinetic performance is compared in both absolute (plot of t0 versus the plate count N or the peak capacity np for isocratic and gradient elution, respectively) and dimensionless units. The latter is realized by switching to so-called impedance plots, a format which has been previously introduced (as a plot of t0/N(2) or E0 versus Nopt/N) and has in the present study been extended from isocratic to gradient elution (where the impedance plot corresponds to a plot of t0/np(4) versus np,opt(2)/np(2)). Both the isocratic and gradient impedance plot yielded a very similar picture: the clustered impedance plot curves divide into two distinct groups, one for the core-shell particles (lowest values, i.e. best performance) and one for the fully porous particles (highest values), confirming the clear intrinsic kinetic advantage of core-shell particles. If used around their optimal flow rate, the core-shell particles displayed a minimal separation impedance that is about 40% lower than the fully porous particles. Even larger gains in separation speed can be achieved in the C-term regime. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Fluid management in the intensive care unit: bioelectrical impedance vector analysis as a tool to assess hydration status and optimal fluid balance in critically ill patients.

    Science.gov (United States)

    Basso, Flavio; Berdin, Giovanna; Virzì, Grazia Maria; Mason, Giacomo; Piccinni, Pasquale; Day, Sonya; Cruz, Dinna N; Wjewodzka, Marzena; Giuliani, Anna; Brendolan, Alessandra; Ronco, Claudio

    2013-01-01

    Fluid balance disorders are a relevant risk factor for morbidity and mortality in critically ill patients. Volume assessment in the intensive care unit (ICU) is thus of great importance, but there are currently few methods to obtain an accurate and timely assessment of hydration status. Our aim was to evaluate the hydration status of ICU patients via bioelectric impedance vector analysis (BIVA) and to investigate the relationship between hydration and mortality. We evaluated 280 BIVA measurements of 64 patients performed daily in the 5 days following their ICU admission. The observation period ranged from a minimum of 72 h up to a maximum of 120 h. We observed the evolution of the hydration status during the ICU stay in this population, and analyzed the relationship between mean and maximum hydration reached and mortality--both in the ICU and at 60 days--using logistic regression. A state of overhydration was observed in the majority of patients (70%) on admission, which persisted during the ICU stay. Patients who required continuous renal replacement therapy (CRRT) were more likely to be overhydrated starting from the 2nd day of observation. Logistic regression showed a strong and significant correlation between mean/maximum hydration reached and mortality, both independently and correcting for severity of prognosis. Fluid overload measured by BIVA is a frequent condition in critically ill patients--whether or not they undergo CRRT--and a significant predictor of mortality. Hence, hydration status should be considered as an additional prognosticator in the clinical management of the critically ill patient. (i) On the day of ICU admittance, patients showed a marked tendency to overhydration (>70% of total). This tendency was more pronounced in patients on CRRT. (ii) Hyperhydration persisted during the ICU stay. Patients who underwent CRRT showed significantly higher hyperhydration from the 2nd day of hospitalization. (iii) Nonsurvivors showed worse hyperhydration

  11. The relationship between bioelectrical impedance phase angle and subjective global assessment in advanced colorectal cancer

    Directory of Open Access Journals (Sweden)

    Grutsch James F

    2008-06-01

    Full Text Available Abstract Background Bioelectrical Impedance (BIA derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. Methods We evaluated a case series of 73 stages III and IV colorectal cancer patients. Patients were classified as either well-nourished or malnourished using the SGA. BIA was conducted on all patients and phase angle was calculated. The correlation between phase angle and SGA was studied using Spearman correlation coefficient. Receiver Operating Characteristic curves were estimated using the non-parametric method to determine the optimal cut-off levels of phase angle. Results Well-nourished patients had a statistically significantly higher (p = 0.005 median phase angle score (6.12 as compared to those who were malnourished (5.18. The Spearman rank correlation coefficient between phase angle and SGA was found to be 0.33 (p = 0.004, suggesting better nutritional status with higher phase angle scores. A phase angle cut-off of 5.2 was 51.7% sensitive and 79.5% specific whereas a cut-off of 6.0 was 82.8% sensitive and 54.5% specific in detecting malnutrition. Interestingly, a phase angle cut-off of 5.9 demonstrated high diagnostic accuracy in males who had failed primary treatment for advanced colorectal cancer. Conclusion Our study suggests that bioimpedance phase angle is a potential nutritional indicator in advanced colorectal cancer. Further research is needed to elucidate the optimal cut-off levels of phase angle that can be incorporated into the oncology clinic for better nutritional evaluation and management.

  12. Short-circuit impedance measurement

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Nielsen, Arne Hejde; Poulsen, Niels Kjølstad

    2003-01-01

    Methods for estimating the short-circuit impedance in the power grid are investigated for various voltage levels and situations. The short-circuit impedance is measured, preferably from naturally occurring load changes in the grid, and it is shown that such a measurement system faces different...

  13. Impedance models in time domain

    NARCIS (Netherlands)

    Rienstra, S.W.

    2005-01-01

    Necessary conditions for an impedance function are derived. Methods available in the literature are discussed. A format with recipe is proposed for an exact impedance condition in time domain on a time grid, based on the Helmholtz resonator model. An explicit solution is given of a pulse reflecting

  14. Intraesophageal impedance monitoring: clinical studies

    NARCIS (Netherlands)

    Conchillo Armendáriz, J.M.

    2007-01-01

    Electrical impedance (Z) between two electrodes is the ratio between applied voltage (U) and resulting current (I). In electrical impedance monitoring the resistance to electrical flow in an alternating current circuit is measured. Multichannel esophageal monitoring can be measured by using an

  15. Modeling code-interactions in bilingual word recognition: Recent empirical studies and simulations with BIA+

    NARCIS (Netherlands)

    Lam, K.J.Y.; Dijkstra, A.F.J.

    2010-01-01

    Daily conversations contain many repetitions of identical and similar word forms. For bilinguals, the words can even come from the same or different languages. How do such repetitions affect the human word recognition system? The Bilingual Interactive Activation Plus (BIA+) model provides a

  16. Agreement Between Bioelectrical Impedance and Dual-Energy X-Ray Absorptiometry to Track Changes in Fat-Free Mass After Resistance Training in Older Women.

    Science.gov (United States)

    Nascimento, Matheus A; Silva, Danilo R P; Ribeiro, Alex S; Pina, Fábio L C; Gerage, Aline M; Gobbo, Luís A; Mayhew, Jerry L; Cyrino, Edilson S

    2018-05-23

    Nascimento, MA, Silva, DRP, Ribeiro, AS, Pina, FLC, Gerage, AM, Gobbo, LA, Mayhew, JL, and Cyrino, ES. Agreement between bioelectrical impedance and dual-energy x-ray absorptiometry to track changes in fat-free mass after resistance training in older women. J Strength Cond Res XX(X): 000-000, 2018-The aim of our study was to compare the agreement between bioelectrical impedance (BIA) and dual-energy X-ray absorptiometry (DXA) to track changes on fat-free mass (FFM) after a resistance training (RT) program in older women. Forty-three older women (65.2 ± 4.6 years, 59.5 ± 9.2 kg, 156.4 ± 6.0 cm, 24.3 ± 3.3 kg·m) participated in a RT intervention (12 weeks, 8 exercises, 2 sets, 10-15 repetitions, 3 nonconsecutive days per week). Fat-free mass changes were determined by a single-frequency BIA device (EQ1), 6 BIA prediction equations for older women (EQ2, EQ3, EQ4, EQ5, EQ6, and EQ7), and DXA. At pretraining, 3 equations overpredicted, and 3 underpredicted DXA FFM (F = 244.63, p FFM (F = 176.25, p FFM (0.65 ± 0.82 kg; p FFM. Low correlations between FFM and equation change values suggest that single-frequency BIA-derived equations may not provide sufficient accuracy to track changes in FFM after 12 weeks of RT in older women.

  17. Modern Trends in Imaging XI: Impedance Measurements in the Biomedical Sciences

    Directory of Open Access Journals (Sweden)

    Frederick D. Coffman

    2012-01-01

    Full Text Available Biological organisms and their component organs, tissues and cells have unique electrical impedance properties. Impedance properties often change with changes in structure, composition, and metabolism, and can be indicative of the onset and progression of disease states. Over the past 100 years, instruments and analytical methods have been developed to measure the impedance properties of biological specimens and to utilize these measurements in both clinical and basic science settings. This chapter will review the applications of impedance measurements in the biomedical sciences, from whole body analysis to impedance measurements of single cells and cell monolayers, and how cellular impedance measuring instruments can now be used in high throughput screening applications.

  18. Microfluidic Impedance Flow Cytometry Enabling High-Throughput Single-Cell Electrical Property Characterization

    Science.gov (United States)

    Chen, Jian; Xue, Chengcheng; Zhao, Yang; Chen, Deyong; Wu, Min-Hsien; Wang, Junbo

    2015-01-01

    This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1) early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2) microfluidic impedance flow cytometry with enhanced sensitivity; (3) microfluidic impedance and optical flow cytometry for single-cell analysis and (4) integrated point of care system based on microfluidic impedance flow cytometry. We examine the advantages and limitations of each technique and discuss future research opportunities from the perspectives of both technical innovation and clinical applications. PMID:25938973

  19. Theoretical analysis and simulation study of low-power CMOS electrochemical impedance spectroscopy biosensor in 55 nm deeply depleted channel technology for cell-state monitoring

    Science.gov (United States)

    Itakura, Keisuke; Kayano, Keisuke; Nakazato, Kazuo; Niitsu, Kiichi

    2018-01-01

    We present an impedance-detection complementary metal oxide semiconductor (CMOS) biosensor circuit for cell-state observation. The proposed biosensor can measure the expected impedance values encountered by a cell-state observation measurement system within a 0.1-200 MHz frequency range. The proposed device is capable of monitoring the intracellular conditions necessary for real-time cell-state observation, and can be fabricated using a 55 nm deeply depleted channel CMOS process. Operation of the biosensor circuit with 0.9 and 1.7 V supply voltages is verified via a simulated program with integrated circuit emphasis (SPICE) simulation. The power consumption is 300 µW. Further, the standby power consumption is 290 µW, indicating that this biosensor is a low-power instrument suitable for use in Internet of Things (IoT) devices.

  20. Analysis of electrical and thermal stress effects on PCBM:P3HT solar cells by photocurrent and impedance spectroscopy modeling

    DEFF Research Database (Denmark)

    Torto, Lorenzo; Rizzo, Antonio; Cester, Andrea

    2017-01-01

    We investigated the effects of electrical stress and thermal storage by means of photocurrent, Impedance Spectroscopy and Open Circuit Voltage Decay models. The electrical stress damages only the active layer, by reducing the generation rate, the polaron separation probability and the carrier...... lifetime. The thermal stress also degrades the anode interface. This reflects on the appearance of an inflection in the I-V photocurrent shape close to the operative region....

  1. Analysis of x-ray diffraction pattern and complex plane impedance plot of polypyrrole/titanium dioxide nanocomposite: A simulation study

    Science.gov (United States)

    Ravikiran, Y. T.; Vijaya Kumari, S. C.

    2013-06-01

    To innovate the properties of Polypyrrole/Titanium dioxide (PPy/TiO2) nanocomposite further, it has been synthesized by chemical polymerization technique. The nanostructure and monoclinic phase of the prepared composite have been confirmed by simulating the X-ray diffraction pattern (XRD). Also, complex plane impedance plot of the composite has been simulated to find equivalent resistance capacitance circuit (RC circuit) and numerical values of R and C have been predicted.

  2. Archives of Voivodship Committee of Polish United Workers’ Party in Biała Podlaska

    Directory of Open Access Journals (Sweden)

    Dariusz Magier

    2010-12-01

    Full Text Available Documentation generated by the communist party after World War II constituted the part of Polish archival heritage. However, Party’s archives were not supervised by nationalarchival network. At the beginning they were storehouses of acts, and since 1955 they had been taken over by propaganda sections of voivodship committees of PZPR (Polish United Workers’ Party and later transformed into the archives of voivodship committees of the Party. The task to preserve documentation generated by the structures of the communist party in Poland was subsequently supervised by: Party HistoryInstitute at KC PZPR (Central Committee of Polish United Workers’ Party, Archives of KC PZPR, and since 1971 Central Archives of KC PZPR. Together with the archives of voivodship committees the net with its own regulations, staff and archival methodology was created. This article gives a detailed description of the activity of the organizational unit,that is the archives of the voivodship committee of the communist party. One of the smallest committees existing in Poland, a provincial Voivodship Committee of PZPR in Biała Podlaska, which operated from 1975 to 1990, serves as an example. The article discusses the reporting structure, handing-over, analysis and preservation of acts, means of recording, premises, system of training and control as well as characterizes the role of a supervisor of the Party’s voidovdship committee Archives played in the archives and chancery.

  3. Determination of beam coupling impedance in the frequency domain

    Energy Technology Data Exchange (ETDEWEB)

    Niedermayer, Uwe

    2016-07-01

    simulations always contain simplifications, therefore they have to be confirmed by dedicated measurements. However, the beam coupling impedance of a single accelerator component cannot be measured directly. Therefore, a dedicated RF-laboratory was established at GSI, in order to measure broadband beam coupling impedances on the bench by means of the wire method, i.e. without beam. A detailed analysis of measurement methods is given by comparison of analytical, numerical, and measurement results for simplified accelerator devices. One conclusion is, that also the bench measurements have to be validated by dedicated electromagnetic simulations. The thesis closes with selected impedance induced effects on the beam revolving in the synchrotron and relevant impedance results for the future SIS-100 synchrotron for the FAIR project at GSI.

  4. Advanced impedance modeling of solid oxide electrochemical cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Hjelm, Johan

    2014-01-01

    Impedance spectroscopy is a powerful technique for detailed study of the electrochemical and transport processes that take place in fuel cells and electrolysis cells, including solid oxide cells (SOCs). Meaningful analysis of impedance measurements is nontrivial, however, because a large number...... techniques to provide good guesses for the modeling parameters, like transforming the impedance data to the distribution of relaxation times (DRT), together with experimental parameter sensitivity studies, is the state-of-the-art approach to achieve good EC model fits. Here we present new impedance modeling...... electrode and 2-D gas transport models which have fewer unknown parameters for the same number of processes, (ii) use of a new model fitting algorithm, “multi-fitting”, in which multiple impedance spectra are fit simultaneously with parameters linked based on the variation of measurement conditions, (iii...

  5. Hybrid-Source Impedance Networks

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    Hybrid-source impedance networks have attracted attention among researchers because of their flexibility in performing buck-boost energy conversion. To date, three distinct types of impedance networks can be summarized for implementing voltage-type inverters with another three types summarized...... for current-type inverters. These impedance networks can in principle be combined into two generic network entities, before multiple of them can further be connected together by applying any of the two proposed generalized cascading concepts. The resulting two-level and three-level inverters implemented using...

  6. Small Signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2014-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterized by the mechanical resonance between the mass of the diaphragm and the compliance of its suspension which vary...... from driver to driver. Therefore, a loudspeaker emulator capable of adjusting its impedance to that of a given driver is desired for measurement purposes. This paper proposes a loudspeaker emulator circuit for small signals. Simulations and experimental results are compared and show that it is possible...... to emulate the loudspeaker impedance with an electric circuit and that its resonance frequency can be changed by tuning two resistors....

  7. 25 CFR 170.805 - What are the local, tribal, and BIA roles in transportation facility maintenance?

    Science.gov (United States)

    2010-04-01

    ... transportation facility maintenance? 170.805 Section 170.805 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER INDIAN RESERVATION ROADS PROGRAM BIA Road Maintenance § 170.805 What are the local... Road Maintenance dollars. ...

  8. 25 CFR 10.11 - How would someone detained or incarcerated, or their representative, get the BIA policies and...

    Science.gov (United States)

    2010-04-01

    ... are used for operations or maintenance programs, the BIA's policies, standards, and procedures will be... physical or mental condition of the person at time of incarceration. In these cases, the Inmate Handbook...

  9. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-08-31

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible to establish quantitative links between electrochemical kinetics and materials properties, even when systems are unstable with time. After a brief review of the method, this paper summarizes recent results analyzing the effects of Sr segregation in thin-film LSC electrodes. © The Electrochemical Society.

  10. A massa gorda de risco afeta a capacidade aeróbia de jovens adolescentes

    Directory of Open Access Journals (Sweden)

    Luís Massuça

    2013-12-01

    Full Text Available OBJETIVO: Estudar o comportamento do sexo e os efeitos da idade e da massa gorda sobre a capacidade aeróbia de jovens adolescentes. MÉTODOS: Os 621 estudantes do ensino secundário participantes no estudo (14 aos 17 anos; feminino: n = 329, idade, 15,84 ± 0,92 anos; masculino: n = 292, idade, 15,82 ± 0,87 anos foram avaliados em duas categorias: morfologia (altura, peso e % massa gorda - %MG e aptidão física (capacidade aeróbia. As medições antropométricas foram realizadas de acordo com o protocolo descrito por Marfell-Jones e a %MG foi calculada por bioimpedância. A avaliação da capacidade aeróbia foi realizada com o teste aeróbio de corrida - PACER, e VO2máx relativo foi calculado utilizando a equação de Léger. Os resultados das avaliações foram classificados de acordo com os valores normativos das tabelas de referência da bateria de testes FITNESSGRAM® As técnicas estatísticas utilizadas foram: 1 cálculo de frequências; 2 teste t de Student para amostras independentes; e 3 ANOVA two-way seguida do teste post-hoc HSD de Bonferroni. RESULTADOS: 1 existem diferenças significativas entre sexos no que se refere à %MG e ao VO2máx; 2 durante a adolescência, o VO2máx estabiliza nos rapazes e sofre um declínio nas moças; 3 independentemente do sexo, a classe de %MG e a idade cronológica têm um efeito significativo sobre a capacidade aeróbia; e 4 em jovens adolescentes, com %MG de risco, a redução da %MG para níveis saudáveis parece resultar na melhoria da capacidade aeróbia. CONCLUSÃO: O impacto da %MG na capacidade aeróbia, reforça a importância da educação física escolar na promoção da saúde cardiovascular.

  11. Analysis and application of impedance polar diagram and zstrike rose diagram of magnetotellurics data in southern part of the Wayang Windu geothermal field

    Science.gov (United States)

    Rohayat, O. R.; Wicaksono, R. A.; Daud, Y.

    2018-03-01

    In this study, we determined the main direction of geoelectric strike in the southern part of the Wayang Windu geothermal field using magnetotellurics (MT) data. The strike direction was obtained by analyzing data using impedance polar and Zstrike rose diagram. We investigated 51 MT data at different sites of the southern part of the Wayang Windu geothermal field. Determination of geoelectric strike direction is important since the strike is the rotation references in MT data processing. Our findings had pointed out that the geoelectric strike direction in this study area is in accordance with the direction of geological structure and has a good correlation with structures delineated from 3D MT inversion model.

  12. IMPEDANCE SPECTROSCOPY OF POLYCRYSTALLINE TIN DIOXIDE FILMS

    Directory of Open Access Journals (Sweden)

    D. V. Adamchuck

    2016-01-01

    Full Text Available The aim of this work is the analysis of the influence of annealing in an inert atmosphere on the electrical properties and structure of non-stoichiometric tin dioxide films by means of impedance spectroscopy method. Non-stoichiometric tin dioxide films were fabricated by two-step oxidation of metallic tin deposited on the polycrystalline Al2O3 substrates by DC magnetron sputtering. In order to modify the structure and stoichiometric composition, the films were subjected to the high temperature annealing in argon atmosphere in temperature range 300–800 °С. AC-conductivity measurements of the films in the frequency range 20 Hz – 2 MHz were carried out. Variation in the frequency dependencies of the real and imaginary parts of the impedance of tin dioxide films was found to occur as a result of high-temperature annealing. Equivalent circuits for describing the properties of films with various structure and stoichiometric composition were proposed. Possibility of conductivity variation of the polycrystalline tin dioxide films as a result of аnnealing in an inert atmosphere was demonstrated by utilizing impedance spectroscopy. Annealing induces the recrystallization of the films, changing in their stoichiometry as well as increase of the sizes of SnO2 crystallites. Variation of electrical conductivity and structure of tin dioxide films as a result of annealing in inert atmosphere was confirmed by X-ray diffraction analysis. Analysis of the impedance diagrams of tin dioxide films was found to be a powerful tool to study their electrical properties. 

  13. DETERMINAÇÃO RÁPIDA E SIMPLES DE CITRATO DE SILDENAFILA (VIAGRA® E GENÉRICOS EMPREGANDO ELETRODO IMPRESSO DE CARBONO EM SISTEMAS FIA E BIA COM DETECÇÃO AMPEROMÉTRICA

    Directory of Open Access Journals (Sweden)

    Rafael S. Backes

    Full Text Available This work presents two amperometric methods for Sildenafil Citrate (SC determination in erectile dysfunction drugs (Viagra® and Generics, using Batch Injection Analysis (BIA and Flow Injection Analysis (FIA systems with a cell for Screen Printed Electrodes (SPE. In Britton- Robinson buffer solution (pH 2, the SC presented an irreversible anodic peak at around +1.0 V vs. Ag pseudo-reference electrode, using five different working electrodes of commercial SPE. The carbon SPE (unmodified was selected as the best working electrode, providing good sensitivity, precision and low-cost. The SC amperometric detection for two proposed methods was performed at +1.1 V. The best conditions for SC determination by hydrodynamic systems were obtained through injection volumes of 50 and 150 µL at flow rates of 100 and 75 µL s-1, for BIA and FIA respectively. In these conditions, BIA system showed the best sensitivity (0.188 µA mol-1 L and theoretical analytical frequency (360 h-1 for SC determination. The repeatability studies were similar for both systems with relative standard deviation of approximately 3.0%. The SC analyses in pharmaceutical samples obtained by two proposed methods were compared to HPLC-UV method.

  14. Impedance/modulus analysis of sol-gel Ba{sub x}Sr{sub 1-x}TiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Saif, Alaeddin A.; Poopalan, P. [University Malaysia Perlis, Perlis (Malaysia)

    2010-12-15

    Perovskite-structure-type sol-gel barium-strontium-titanate (BST) thin films with molar formula Ba{sub x}Sr{sub 1-x}TiO{sub 3} (x = 0.5, 0.6, 0.7, and 0.8) have been successfully fabricated as Al/BST/Pt capacitors. In order to study the role of the grain size in the conduction mechanisms, we present atomic force microscopy (AFM) results. The impedance and the electric modulus of Ba{sub x}Sr{sub 1-x}TiO{sub 3} thin films have been analyzed in order to correlate the effect of the film regional processes on the conduction mechanism. The impedance and the electric modulus complex planes show three overlapping regions as response for the bulk, the grain boundary and the film/electrode interface mechanisms, and an equivalent circuit has been proposed for each mechanism. The conduction mechanism resulting from the bulk and the grain boundaries is discussed; the results show that the grain boundaries have less effect on the conduction mechanism than the bulk.

  15. Physiological analysis of the effects of rikkunshito on acid and non-acid gastroesophageal reflux using pH-multichannel intraluminal impedance monitoring.

    Science.gov (United States)

    Kawahara, Hisayoshi; Tazuke, Yuko; Soh, Hideki; Yoneda, Akihiro; Fukuzawa, Masahiro

    2014-09-01

    To clarify the effects of rikkunshito on acid reflux, non-acid reflux, and esophageal clearance in patients with gastroesophageal reflux disease (GERD). We enrolled seven patients with vomiting and/or stridor (median 6 years; 1 month-17 years), with a percent total time of esophageal pH reflux index) over 4.0%. Rikkunshito (TJ-43; Tsumura Co, Tokyo, Japan) was given in three divided doses before meals. We retrospectively investigated its efficacy using pH-multichannel intraluminal impedance before and 7 (6-10) days after starting treatment. Statistical analyses were conducted using Wilcoxon signed-rank test. In the pH analyses alone, the median number of acid reflux episodes >5 min (14 versus 10, p = 0.046) and median acid-clearance time (184 versus 134 s, p = 0.03) decreased significantly, although median decrease in reflux index did not reach significance (16.0 versus 17.9%, p = 0.06). In the combined impedance and pH analyses, the median number (36 versus 36, p = 0.03) and median duration (1.9 versus 1.1%, p = 0.046) of acid reflux decreased significantly; non-acid reflux and bolus clearance time did not change. Rikkunshito effectively reduced acid reflux, but not esophageal clearance, in patients with GERD.

  16. Microwave impedance imaging on semiconductor memory devices

    Science.gov (United States)

    Kundhikanjana, Worasom; Lai, Keji; Yang, Yongliang; Kelly, Michael; Shen, Zhi-Xun

    2011-03-01

    Microwave impedance microscopy (MIM) maps out the real and imaginary components of the tip-sample impedance, from which the local conductivity and dielectric constant distribution can be derived. The stray field contribution is minimized in our shielded cantilever design, enabling quantitative analysis of nano-materials and device structures. We demonstrate here that the MIM can spatially resolve the conductivity variation in a dynamic random access memory (DRAM) sample. With DC or low-frequency AC bias applied to the tip, contrast between n-doped and p-doped regions in the dC/dV images is observed, and p-n junctions are highlighted in the dR/dV images. The results can be directly compared with data taken by scanning capacitance microscope (SCM), which uses unshielded cantilevers and resonant electronics, and the MIM reveals more information of the local dopant concentration than SCM.

  17. MD 349: Impedance Localization with AC-dipole

    CERN Document Server

    Biancacci, Nicolo; Metral, Elias; Salvant, Benoit; Papotti, Giulia; Persson, Tobias Hakan Bjorn; Tomas Garcia, Rogelio; CERN. Geneva. ATS Department

    2016-01-01

    The purpose of this MD is to measure the distribution of the transverse impedance of the LHC by observing the phase advance variation with intensity between the machine BPMs. Four injected bunches with different intensities are excited with an AC dipole and the turn by turn data is acquired from the BPM system. Through post-processing analysis the phase variation along the machine is depicted and, from this information, first conclusions of the impedance distribution can be drawn.

  18. Impedance Characterisation of the SPS Wire Scanner

    CERN Document Server

    AUTHOR|(CDS)2091911; Prof. Sillanpää, Mika

    As a beam diagnostic tool, the SPS wire scanner interacts with the proton bunches traversing the vacuum pipes of the Super Proton Synchrotron particle accelerator. Following the interaction, the bunches decelerate or experience momentum kicks off-axis and couple energy to the cavity walls, resonances and to the diagnostic tool, the scanning wire. The beam coupling impedance and, in particular, the beam induced heating of the wire motivate the characterisation and redesign of the SPS wire scanner. In this thesis, we characterise RF-wise the low frequency modes of the SPS wire scanner. These have the highest contribution to the impedance. We measure the cavity modes in terms of resonance frequency and quality factor by traditional measurement techniques and data analysis. We carry out a 4-port measurement to evaluate the beam coupling to the scanning wire, that yields the spectral heating power. If combined with the simulations, one is able to extract the beam coupling impedance and deduce the spectral dissipa...

  19. Y-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Loh, Poh Chiang; Blaabjerg, Frede

    2014-01-01

    This letter introduces a new versatile Y-shaped impedance network for realizing converters that demand a very high-voltage gain, while using a small duty ratio. To achieve that, the proposed network uses a tightly coupled transformer with three windings, whose obtained gain is presently not matched...... by existing networks operated at the same duty ratio. The proposed impedance network also has more degrees of freedom for varying its gain, and hence, more design freedom for meeting requirements demanded from it. This capability has been demonstrated by mathematical derivation, and proven in experiment...

  20. How the Inductive Voltage Adder (IVA) output impedance affects impedance dynamics of a Self-Magnetic Pinch (SMP) diode

    Science.gov (United States)

    Renk, Timothy; Simpson, Sean; Webb, Timothy; Mazarakis, Michael; Kiefer, Mark

    2016-10-01

    The SMP diode, fielded on the RITS-6 (3.5-8.5 MV) IVA accelerator at Sandia National Laboratories, produces a focused electron beam (transmission line (MITL) center conductors, of 40 and 80 ohms flow impedance. We have operated in-situ heating and discharge-cleaning hardware in the load region, in order to address the tendency of some shots to undergo premature impedance (Z) collapse, defined as a fall in impedance beyond that due to normal movement of electrode plasmas that reduces the effective A-K gap. The goal of heating/cleaning was to reduce the volume of evolving gases near the A-K gap. Despite clear evidence that the cleaning techniques removed the proton portion of beam current, we observed no consistent increase in diode impedance (ZDIODE). This forced an examination of the role that the IVA flow impedance has on ZDIODE. A preliminary conclusion is that ZDIODE should be at least 1.5 times the flow impedance before ZDIODE is a parameter independent of flow impedance. This has implications for SMP as a load for a IVA, since ZDIODE >100 ohms has not been consistently demonstrated. Data analysis is ongoing, and latest results will be reported. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  1. Entrance and Exit CSR Impedance for Non-Ultrarelativistic Beam

    Energy Technology Data Exchange (ETDEWEB)

    Li, Rui; Tsai, Cheng Ying [SLAC National Accelerator Lab., Menlo Park, CA (United States); Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2017-05-01

    For a high-brightness electron beam being transported through beamlines involving bending systems, the coherent synchrotron radiation (CSR) and longitudinal space charge (LSC) interaction could often cause microbunching instability. The semi-analytical Vlasov solver for microbunching gain* depends on the impedances for the relevant collective effects. The existing results for CSR impedances are usually obtained for the ultrarelativistic limit. To extend the microbunching analysis to cases of low energies, such as the case of an ERL merger, or to density modulations at extremely small wavelength, it is necessary to extend the impedance analysis to the non-ultrarelativistic regime. In this study, we present the impedance analysis for the transient CSR interaction in the non-ultrarelativistic regime, for transients including both entrance to and exit from a magnetic dipole. These impedance results will be compared to their ultra-relativistic counterparts**, and the corresponding wakefield obtained from the impedance for low-energy beams will be compared with the existing results of transient CSR wakefield for general beam energies***.

  2. Unified Impedance Model of Grid-Connected Voltage-Source Converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Harnefors, Lennart; Blaabjerg, Frede

    2018-01-01

    This paper proposes a unified impedance model of grid-connected voltage-source converters for analyzing dynamic influences of the Phase-Locked Loop (PLL) and current control. The mathematical relations between the impedance models in the different domains are first explicitly revealed by means...... of complex transfer functions and complex space vectors. A stationary (αβ-) frame impedance model is then proposed, which not only predicts the stability impact of the PLL, but reveals also its frequency coupling effect explicitly. Furthermore, the impedance shaping effect of the PLL on the current control...... results and theoretical analysis confirm the effectiveness of the stationary-frame impedance model....

  3. Low profile conformal antenna arrays on high impedance substrate

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    This book presents electromagnetic (EM) design and analysis of dipole antenna array over high impedance substrate (HIS). HIS is a preferred substrate for low-profile antenna design, owing to its unique boundary conditions. Such substrates permit radiating elements to be printed on them without any disturbance in the radiation characteristics. Moreover HIS provides improved impedance matching, enhanced bandwidth, and increased broadside directivity owing to total reflection from the reactive surface and high input impedance. This book considers different configurations of HIS for array design on planar and non-planar high-impedance surfaces. Results are presented for cylindrical dipole, printed dipole, and folded dipole over single- and double-layered square-patch-based HIS and dogbone-based HIS. The performance of antenna arrays is analyzed in terms of performance parameters such as return loss and radiation pattern. The design presented shows acceptable return loss and mainlobe gain of radiation pattern. Thi...

  4. Baltic Sea coastal erosion; a case study from the Jastrzębia Góra region

    Directory of Open Access Journals (Sweden)

    Uścinowicz Grzegorz

    2014-12-01

    Full Text Available The coastline in the Jastrzębia Góra area can be divided into three major zones of general importance: a beach and barrier section, a cliff section, and a section protected by a heavy hydrotechnical construction. These areas are characterised by a diverse geology and origin, and hence different vulnerability to erosion. In addition, observations have demonstrated a different pace of erosion within each zone. Based on the results obtained by remote sensing methods (analysis of aerial photographs and maps, it has been determined that the coastline in the barrier area, i.e., to the west of Jastrzębia Góra, moved landwards by about 130 m, in a period of 100 years, and 80 m over about 50 years. A smaller displacement of the shoreline could be observed within the cliff. Between the middle of the twentieth and the start of the twenty-first centuries the shore retreated by about 25 m. However, in recent years, an active landslide has led to the displacement of the uppermost part of the cliff locally up to 25 m. Another issue is, functioning since 2000, a heavy hydrotechnical construction which has been built in order to protect the most active part of the cliff. The construction is not stable and its western part, over a distance of 50 m, has moved almost 2 m vertically downwards and c. 2.5 m horizontally towards the sea in the past two years. This illustrates that the erosional factor does not comprise only marine abrasion, but also involves land-based processes determined by geology and hydrogeology. Changes in the shoreline at the beach and barrier part are constantly conditioned by rising sea levels, the slightly sloping profile of the sea floor and low elevation values of the backshore and dune areas. Cliffs are destroyed by mass wasting and repetitive storm surges that are responsible for the removal of the colluvium which protects the coast from adverse wave effects. Presumably, mass movements combined with groundwater outflow from the cliff

  5. Cytotoxicity evaluation of nanoclays in human epithelial cell line A549 using high content screening and real-time impedance analysis

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Navin K. [Trinity College Dublin, Department of Clinical Medicine, Institute of Molecular Medicine (Ireland); Moore, Edward; Blau, Werner [Trinity College Dublin, School of Physics (Ireland); Volkov, Yuri [Trinity College Dublin, Department of Clinical Medicine, Institute of Molecular Medicine (Ireland); Ramesh Babu, P., E-mail: babup@tcd.ie [Trinity College Dublin, Centre for Research on Adaptive Nanostructures and Nanodevices (Ireland)

    2012-09-15

    Continuously expanding use of products containing nanoclays for wide range of applications have raised public concerns about health and safety. Although the products containing nanoclays may not be toxic, it is possible that nanomaterials may come in contact with humans during handling, manufacture, or disposal, and cause adverse health impact. This necessitates biocompatibility evaluation of the commonly used nanoclays. Here, we investigated the cytotoxic effects of platelet (Bentone MA, ME-100, Cloisite Na{sup +}, Nanomer PGV, and Delite LVF) and tubular (Halloysite, and Halloysite MP1) type nanoclays on cultured human lung epithelial cells A549. For the first time with this aim, we employed a cell-based automated high content screening in combination with real-time impedance sensing. We demonstrate varying degree of dose- and time-dependent cytotoxic effects of both nanoclay types. Overall, platelet structured nanoclays were more cytotoxic than tubular type. A low but significant level of cytotoxicity was observed at 25 {mu}g/mL of the platelet-type nanoclays. A549 cells exposed to high concentration (250 {mu}g/mL) of tubular structured nanoclays showed inhibited cell growth. Confocal microscopy indicated intracellular accumulation of nanoclays with perinuclear localization. Results indicate a potential hazard of nanoclay-containing products at significantly higher concentrations, which warrant their further biohazard assessment on the actual exposure in humans.

  6. Cytotoxicity evaluation of nanoclays in human epithelial cell line A549 using high content screening and real-time impedance analysis

    International Nuclear Information System (INIS)

    Verma, Navin K.; Moore, Edward; Blau, Werner; Volkov, Yuri; Ramesh Babu, P.

    2012-01-01

    Continuously expanding use of products containing nanoclays for wide range of applications have raised public concerns about health and safety. Although the products containing nanoclays may not be toxic, it is possible that nanomaterials may come in contact with humans during handling, manufacture, or disposal, and cause adverse health impact. This necessitates biocompatibility evaluation of the commonly used nanoclays. Here, we investigated the cytotoxic effects of platelet (Bentone MA, ME-100, Cloisite Na + , Nanomer PGV, and Delite LVF) and tubular (Halloysite, and Halloysite MP1) type nanoclays on cultured human lung epithelial cells A549. For the first time with this aim, we employed a cell-based automated high content screening in combination with real-time impedance sensing. We demonstrate varying degree of dose- and time-dependent cytotoxic effects of both nanoclay types. Overall, platelet structured nanoclays were more cytotoxic than tubular type. A low but significant level of cytotoxicity was observed at 25 μg/mL of the platelet-type nanoclays. A549 cells exposed to high concentration (250 μg/mL) of tubular structured nanoclays showed inhibited cell growth. Confocal microscopy indicated intracellular accumulation of nanoclays with perinuclear localization. Results indicate a potential hazard of nanoclay-containing products at significantly higher concentrations, which warrant their further biohazard assessment on the actual exposure in humans.

  7. 25 CFR 161.610 - What will BIA do if livestock is not removed when a permit expires or is cancelled?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false What will BIA do if livestock is not removed when a permit expires or is cancelled? 161.610 Section 161.610 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF... will BIA do if livestock is not removed when a permit expires or is cancelled? If the livestock is not...

  8. 25 CFR 1000.68 - May non-BIA bureaus provide technical assistance to a Tribe/Consortium in drafting its planning...

    Science.gov (United States)

    2010-04-01

    ... Financial Assistance for Planning and Negotiation Grants for Non-BIA Programs Eligibility and Application... Tribe/Consortium in drafting its planning grant application? 1000.68 Section 1000.68 Indians OFFICE OF... planning grant application? Yes, upon request from the Tribe/Consortium, a non-BIA bureau may provide...

  9. 25 CFR 115.605 - What information will the BIA include in its notice of the decision to restrict your IIM account?

    Science.gov (United States)

    2010-04-01

    ...: Hearing Process for Restricting an IIM Account § 115.605 What information will the BIA include in its... notice of its decision to restrict your account, the only information the public notice will include is... 25 Indians 1 2010-04-01 2010-04-01 false What information will the BIA include in its notice of...

  10. 25 CFR 115.602 - How will the BIA notify you or your guardian, as applicable, of its decision to restrict your IIM...

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false How will the BIA notify you or your guardian, as... guardian, as applicable, of its decision to restrict your IIM account? The BIA will notify you or your guardian, as applicable, of its decision to restrict your IIM account by: (a) United States certified mail...

  11. 25 CFR 115.423 - If you are a custodial parent, a legal guardian, or an emancipated minor, may BIA authorize the...

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false If you are a custodial parent, a legal guardian, or an emancipated minor, may BIA authorize the disbursement of funds from a minor's supervised account without your... custodial parent, a legal guardian, or an emancipated minor, may BIA authorize the disbursement of funds...

  12. DXA, bioelectrical impedance, ultrasonography and biometry for the estimation of fat and lean mass in cats during weight loss

    Directory of Open Access Journals (Sweden)

    Borges Naida C

    2012-07-01

    Full Text Available Abstract Background Few equations have been developed in veterinary medicine compared to human medicine to predict body composition. The present study was done to evaluate the influence of weight loss on biometry (BIO, bioimpedance analysis (BIA and ultrasonography (US in cats, proposing equations to estimate fat (FM and lean (LM body mass, as compared to dual energy x-ray absorptiometry (DXA as the referenced method. For this were used 16 gonadectomized obese cats (8 males and 8 females in a weight loss program. DXA, BIO, BIA and US were performed in the obese state (T0; obese animals, after 10% of weight loss (T1 and after 20% of weight loss (T2. Stepwise regression was used to analyze the relationship between the dependent variables (FM, LM determined by DXA and the independent variables obtained by BIO, BIA and US. The better models chosen were evaluated by a simple regression analysis and means predicted vs. determined by DXA were compared to verify the accuracy of the equations. Results The independent variables determined by BIO, BIA and US that best correlated (p r2, 19 equations were selected (12 for FM, 7 for LM; however, only 7 equations accurately predicted FM and one LM of cats. Conclusions The equations with two variables are better to use because they are effective and will be an alternative method to estimate body composition in the clinical routine. For estimated lean mass the equations using body weight associated with biometrics measures can be proposed. For estimated fat mass the equations using body weight associated with bioimpedance analysis can be proposed.

  13. Detection of muscle gap by L-BIA in muscle injuries: clinical prognosis.

    Science.gov (United States)

    Nescolarde, L; Yanguas, J; Terricabras, J; Lukaski, H; Alomar, X; Rosell-Ferrer, J; Rodas, G

    2017-06-21

    Sport-related muscle injury classifications are based basically on imaging criteria such as ultrasound (US) and magnetic resonance imaging (MRI) without consensus because of a lack of clinical prognostics for return-to-play (RTP), which is conditioned upon the severity of the injury, and this in turn with the muscle gap (muscular fibers retraction). Recently, Futbol Club Barcelona's medical department proposed a new muscle injury classification in which muscle gap plays an important role, with the drawback that it is not always possible to identify by MRI. Localized bioimpedance measurement (L-BIA) has emerged as a non-invasive technique for supporting US and MRI to quantify the disrupted soft tissue structure in injured muscles. To correlate the severity of the injury according to the gap with the RTP, through the percent of change in resistance (R), reactance (Xc) and phase-angle (PA) by L-BIA measurements in 22 muscle injuries. After grouping the data according to the muscle gap (by MRI exam), there were significant differences in R between grade 1 and grade 2f (myotendinous or myofascial muscle injury with feather-like appearance), as well as between grade 2f and grade 2g (myotendinous or myofascial muscle injury with feather and gap). The Xc and PA values decrease significantly between each grade (i.e. 1 versus 2f, 1 versus 2g and 2f versus 2g). In addition, the severity of the muscle gap adversely affected the RTP with significant differences observed between 1 and 2g as well as between 2f and 2g. These results show that L-BIA could aid MRI and US in identifying the severity of an injured muscle according to muscle gap and therefore to accurately predict the RTP.

  14. Functional Characterization of 4´OMT and 7OMT Genes in BIA Biosynthesis

    Directory of Open Access Journals (Sweden)

    Tugba eGurkok

    2016-02-01

    Full Text Available Alkaloids are diverse group of secondary metabolites generally found in plants. Opium poppy (Papaver somniferum L., the only commercial source of morphinan alkaloids, has been used as a medicinal plant since ancient times. It produces benzylisoquinoline alkaloids (BIA including the narcotic analgesic morphine, the muscle relaxant papaverine, and the anti-cancer agent noscapine. Though BIAs play crucial roles in many biological mechanisms their steps in biosynthesis and the responsible genes remain to be revealed. In this study, expressions of 3-hydroxy-N-methylcoclaurine 4´-O-methyltransferase (4´OMT and reticuline 7-O-methyltransferase (7OMT genes were subjected tomanipulation to functionally characterize their roles in BIA biosynthesis. Measurements of alkaloid accumulation were performed in leaf, stem and capsule tissues accordingly. Suppression of 4´OMT expression caused reduction in the total alkaloid content in stem tissue whereas total alkaloid content was significantly induced in the capsule. Silencing of the 7OMT gene also caused repression in total alkaloid content in the stem. On the other hand, over-expression of 4´OMT and 7OMT resulted in higher morphine accumulation in the stem but suppressed amount in the capsule. Moreover, differential expression in several BIA synthesis genes (CNMT, TYDC, 6OMT, SAT, COR, 4´OMT and 7OMT were observed upon manipulation of 4´OMT and 7OMT expression. Upon silencing and overexpression applications, tissue specific effects of these genes were identified. Manipulation of 4´OMT and 7OMT genes caused differentiated accumulation of BIAs including morphine and noscapine in capsule and stem tissues.

  15. Od internacjonalnej do własnej historii – mniejszość białoruska w Polsce

    Directory of Open Access Journals (Sweden)

    Wojciech Śleszyński

    2017-12-01

    Full Text Available From international history to one’s own history – Belorusian minority in Poland After World War II the Belarusians who did not leave Poland could gain upward mobility only if they avoided displaying their national and cultural distinctiveness. Belarusians made a political choice which coincided with a vision of history and thus accepted a historical narrative spread by communist circles. The narrative constructed by the Belarusian minority was consistent with the officially proclaimed state ideological narrative. It contained mostly the history of the Communist Party of Western Belarus and described a difficult situation of Belarus in the Second Polish Republic and during World War II (especially the Great Patriotic War. The Belarusian community made first attempts to rebuild the current vision of the world in 1980–1981. Students tried to create an alternative historical narrative that contradicted the communist one. However, it was a gradual collapse of the communist system that became an impetus for more active development of the Belarusian minority in Poland, and consequently, the creation of its own national vision of history. The Belarusian heritage has been based on the Belarusian People's Republic and the Grand Duchy of Lithuania, and not, as it was in the Soviet Socialist Republic of Belarus or after 1994, on the Republic of Belarus and the victory in the Great Patriotic War.   Od internacjonalnej do własnej historii – mniejszość białoruska w Polsce Pozostała w Polsce po II wojnie światowej społeczność białoruska uzyskała możliwość awansu społecznego pod warunkiem nieeksponowania swojej narodowej i kulturowej odrębności. Białorusini, dokonując wyboru politycznego, pokrywającego się z wyborem wizji historii, akceptowali obraz dziejów prezentowany przez środowiska komunistyczne. Konstruowany przez mniejszość białoruską przekaz historyczny zgodny był z oficjalnie głoszonym państwowym przekazem

  16. Zakład Medycyny Sądowej w Bielsku-Białej

    Directory of Open Access Journals (Sweden)

    Jerzy Brzyski

    2014-10-01

    Full Text Available Zakład Medycyny Sądowej w Bielsku-Białej został utworzony w 1978 roku. Podstawą dla jego utworzenia i wpisania w strukturę Wojewódzkiego Szpitala Zespolonego były wytyczne Ministra Zdrowia i Opieki Społecznej z dnia 15.06.1978 roku w sprawie organizacji i zadań komórek medycyny sądowej (Dz.U. MZiOS Nr 11, poz 28.

  17. Impedance-matched Marx generators

    Directory of Open Access Journals (Sweden)

    W. A. Stygar

    2017-04-01

    Full Text Available We have conceived a new class of prime-power sources for pulsed-power accelerators: impedance-matched Marx generators (IMGs. The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with LC time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22-Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19-Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-power-output time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.

  18. Impedance-matched Marx generators

    Science.gov (United States)

    Stygar, W. A.; LeChien, K. R.; Mazarakis, M. G.; Savage, M. E.; Stoltzfus, B. S.; Austin, K. N.; Breden, E. W.; Cuneo, M. E.; Hutsel, B. T.; Lewis, S. A.; McKee, G. R.; Moore, J. K.; Mulville, T. D.; Muron, D. J.; Reisman, D. B.; Sceiford, M. E.; Wisher, M. L.

    2017-04-01

    We have conceived a new class of prime-power sources for pulsed-power accelerators: impedance-matched Marx generators (IMGs). The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with L C time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22 -Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19 -Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-power-output time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.

  19. Analytic model of Applied-B ion diode impedance behavior

    International Nuclear Information System (INIS)

    Miller, P.A.; Mendel, C.W. Jr.

    1987-01-01

    An empirical analysis of impedance data from Applied-B ion diodes used in seven inertial confinement fusion research experiments was published recently. The diodes all operated with impedance values well below the Child's-law value. The analysis uncovered an unusual unifying relationship among data from the different experiments. The analysis suggested that closure of the anode-cathode gap by electrode plasma was not a dominant factor in the experiments, but was not able to elaborate the underlying physics. Here we present a new analytic model of Applied-B ion diodes coupled to accelerators. A critical feature of the diode model is based on magnetic insulation theory. The model successfully describes impedance behavior of these diodes and supports stimulating new viewpoints of the physics of Applied-B ion diode operation

  20. Cascaded impedance networks for NPC inverter

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...

  1. Journal bearing impedance descriptions for rotordynamic applications

    NARCIS (Netherlands)

    Childs, D.W.; Moes, H.; Leeuwen, van H.J.

    1977-01-01

    Bearing impedance vectors are introduced for plain journal bearings which define the bearing reaction force components as a function of the bearing motion. Impedance descriptions are developed directly for the approximate Ocvirk (short) and Sommerfeld (long) bearing solutions. The impedance vector

  2. Comparison of bioimpedance analysis scan, hemoglobin and urea reduction ratio in hemodialysis patients following and not following monitoring program for improving quality of life

    Science.gov (United States)

    Muzasti, R. A.; Lubis, H. R.

    2018-03-01

    Hemodialysis (HD) is the renal replacement therapy in end-stage renal disease (ESRD), at least 2-3 times a week, impacting substantial changes in daily life. Therefore a monitoring program is needed to improve the quality of life (QoL) of HD patients. Indicators in monitoring QoL include phase angle (PhA), muscle and fat mass, and body fluid composition through Bio Scan impedance analysis (BIA) Scan, hemoglobin level, and urea reduction ratio (URR). An analytic study with the cross-sectional design was performed in 168 patients at Klinik Spesialis Ginjal Hipertensi (KSGH) Rasyida, Medan to compare BIA Scan profiles, hemoglobin levels, and URR in HD patients who follow and do not follow the monitoring program for improving QoL {Program Pemantauan Peningkatan Kualitas Hidup (P3KH)}. Each variable was analyzed by independent T-test, it is significant if p <0.05. This study showed that there were differences in BMI (p = 0.006), fat mass (p = 0.010), extracellular water / intracellular water (ECW / ICW) (p = 0.046), and haemoglobin p = 0.001). Although it was better in the program group, statistically there was no difference of PhA (p = 0.136), muscle mass (p = 0.842), and URR (p = 0.232).

  3. Observations involving broadband impedance modelling

    International Nuclear Information System (INIS)

    Berg, J.S.

    1995-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impendance. This paper discusses three aspects of broadband impendance modeling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f cavity. The last is a discussion of requirements for the mathematical form of an impendance which follow from the general properties of impendances

  4. Effects of tissue impedance on heat generation during RF delivery with the Thermage system

    Science.gov (United States)

    Tomkoria, Sara; Pope, Karl

    2005-04-01

    The Thermage ThermaCool TC system is a non-ablative RF device designed to promote tissue tightening and contouring. The system delivers RF energy to a target area under the skin, with volumetric tissue heating in that area. While the amount of energy delivered to a patient can be controlled by ThermaCool system settings, the distribution of energy to the treatment area and underlying layers is variable from individual to individual due to differences in body composition. The present study investigated how local tissue impedance affects the amount of discomfort experienced by patients during RF energy delivery. Discomfort results from heat generation in the treatment area. By using features of the ThermaCool TC System, local impedance (impedance of the treatment area), bulk impedance (impedance of the underlying tissue layers), and total impedance (the sum of local and bulk impedance) were measured for 35 patients. For each patient, impedance measurements were compared to discomfort levels expressed during treatment. Analysis of whole body, local, and bulk impedance values indicate that the percent of total body impedance in the local treatment area contributes to discomfort levels expressed by patients during treatment.

  5. 25 CFR 161.713 - How will BIA determine the amount of damages to Navajo Partitioned Lands?

    Science.gov (United States)

    2010-04-01

    ... per month for comparable property or grazing privileges, or the estimated commercial value or replacement costs of the products or property. (c) BIA will determine the value of the products or property illegally used or removed based upon a valuation of similar products or property. ...

  6. 25 CFR 115.601 - Under what circumstances may the BIA restrict your IIM account through supervision or an...

    Science.gov (United States)

    2010-04-01

    ... property, including your financial affairs;” or (3) Determines through an administrative process that you... professional that you are “incapable of managing or administering property, including your financial affairs... IIM funds as security/collateral for the transaction; (ii) A copy of the document showing that the BIA...

  7. 25 CFR 166.819 - What happens if the BIA does not collect enough money to satisfy the penalty?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false What happens if the BIA does not collect enough money to... does not collect enough money to satisfy the penalty? We will send written notice to the trespasser demanding immediate settlement and advising the trespasser that unless settlement is received within five...

  8. Activity-based protein profiling reveals off-target proteins of the FAAH inhibitor BIA 10-2474

    NARCIS (Netherlands)

    van Esbroeck, Annelot C M; Janssen, Antonius P A; Cognetta, Armand B; Ogasawara, Daisuke; Shpak, Guy; van der Kroeg, Mark; Kantae, Vasudev; Baggelaar, Marc P; de Vrij, Femke M S; Deng, Hui; Allarà, Marco; Fezza, Filomena; Lin, Zhanmin; van der Wel, Tom; Soethoudt, Marjolein; Mock, Elliot D; den Dulk, Hans; Baak, Ilse L; Florea, Bogdan I; Hendriks, Giel; De Petrocellis, Luciano; Overkleeft, Herman S; Hankemeier, Thomas; De Zeeuw, Chris I; Di Marzo, Vincenzo; Maccarrone, Mauro; Cravatt, Benjamin F; Kushner, Steven A; van der Stelt, Mario

    2017-01-01

    A recent phase 1 trial of the fatty acid amide hydrolase (FAAH) inhibitor BIA 10-2474 led to the death of one volunteer and produced mild-to-severe neurological symptoms in four others. Although the cause of the clinical neurotoxicity is unknown, it has been postulated, given the clinical safety

  9. 25 CFR 103.32 - What sort of loan documentation does BIA expect the lender to maintain?

    Science.gov (United States)

    2010-04-01

    ... other documentation of efforts to liquidate loan collateral; and (i) Originals or copies, as appropriate... 25 Indians 1 2010-04-01 2010-04-01 false What sort of loan documentation does BIA expect the... FINANCIAL ACTIVITIES LOAN GUARANTY, INSURANCE, AND INTEREST SUBSIDY Loan Servicing Requirements § 103.32...

  10. 25 CFR 103.16 - How does BIA approve or reject a loan guaranty or insurance application?

    Science.gov (United States)

    2010-04-01

    ..., or if necessary, from liquidating loan collateral. Lenders are expected to obtain a first lien security interest in enough collateral to reasonably secure repayment of each loan guaranteed or insured... 25 Indians 1 2010-04-01 2010-04-01 false How does BIA approve or reject a loan guaranty or...

  11. 25 CFR 171.500 - How does BIA determine the annual operation and maintenance assessment rate for the irrigation...

    Science.gov (United States)

    2010-04-01

    ... costs needed for the reliable operation of the irrigation facility infrastructure; (8) Maintenance of a... 25 Indians 1 2010-04-01 2010-04-01 false How does BIA determine the annual operation and... Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER IRRIGATION OPERATION AND...

  12. 25 CFR 103.19 - When must the lender pay BIA the loan guaranty or insurance premium?

    Science.gov (United States)

    2010-04-01

    ... insurance premium? 103.19 Section 103.19 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR FINANCIAL ACTIVITIES LOAN GUARANTY, INSURANCE, AND INTEREST SUBSIDY How a Lender Obtains a Loan Guaranty or Insurance Coverage § 103.19 When must the lender pay BIA the loan guaranty or insurance premium? The premium...

  13. A temporal-omic study of Propionibacterium freudenreichii CIRM-BIA1 adaptation strategies in conditions mimicking cheese ripening in the cold.

    Directory of Open Access Journals (Sweden)

    Marion Dalmasso

    Full Text Available Propionibacterium freudenreichii is used as a ripening culture in Swiss cheese manufacture. It grows when cheeses are ripened in a warm room (about 24°C. Cheeses with an acceptable eye formation level are transferred to a cold room (about 4°C, inducing a marked slowdown of propionic fermentation, but P. freudenreichii remains active in the cold. To investigate the P. freudenreichii strategies of adaptation and survival in the cold, we performed the first global gene expression profile for this species. The time-course transcriptomic response of P. freudenreichii CIRM-BIA1(T strain was analyzed at five times of incubation, during growth at 30°C then for 9 days at 4°C, under conditions preventing nutrient starvation. Gene expression was also confirmed by RT-qPCR for 28 genes. In addition, proteomic experiments were carried out and the main metabolites were quantified. Microarray analysis revealed that 565 genes (25% of the protein-coding sequences of P. freudenreichii genome were differentially expressed during transition from 30°C to 4°C (P1. At 4°C, a general slowing down was observed for genes implicated in the cell machinery. On the contrary, P. freudenreichii CIRM-BIA1(T strain over-expressed genes involved in lactate, alanine and serine conversion to pyruvate, in gluconeogenesis, and in glycogen synthesis. Interestingly, the expression of different genes involved in the formation of important cheese flavor compounds, remained unchanged at 4°C. This could explain the contribution of P. freudenreichii to cheese ripening even in the cold. In conclusion, P. freudenreichii remains metabolically active at 4°C and induces pathways to maintain its long-term survival.

  14. Multifrequency right-side, localized and segmental BIA obtained with different bioimpedance analysers

    International Nuclear Information System (INIS)

    Bogónez-Franco, P; McAdams, E; Nescolarde, L; Rosell-Ferrer, J

    2015-01-01

    The aim of this study is to compare two commercial bioimpedance analysers, BioparHom Z-Métrix and Impedimed SFB7, measuring the impedance of three different body segments. The segments measured were ‘right-side’ (or ‘whole-body’), ‘segmental right-lower limb’ and ‘localized longitudinal right-quadriceps’. The comparison was made on electrical models of each segment, including electrode–skin impedance, and in vivo on nine healthy volunteers. Both devices are designed to measure right-side impedances and, in the present study, as the length of the segment investigated decreased, the accuracy of the impedance measured was found to decrease. The accuracy of the devices was calculated via measurements performed on RC networks of known values. It was found that adding electrode–skin contact impedances in the electrical model affected the accuracy by both devices. (paper)

  15. Spheromak Impedance and Current Amplification

    International Nuclear Information System (INIS)

    Fowler, T K; Hua, D D; Stallard, B W

    2002-01-01

    It is shown that high current amplification can be achieved only by injecting helicity on the timescale for reconnection, τ REC , which determines the effective impedance of the spheromak. An approximate equation for current amplification is: dI TOR 2 /dt ∼ I 2 /τ REC - I TOR 2 /τ closed where I is the gun current, I TOR is the spheromak toroidal current and τ CLOSED is the ohmic decay time of the spheromak. Achieving high current amplification, I TOR >> I, requires τ REC CLOSED . For resistive reconnection, this requires reconnection in a cold zone feeding helicity into a hot zone. Here we propose an impedance model based on these ideas in a form that can be implemented in the Corsica-based helicity transport code. The most important feature of the model is the possibility that τ REC actually increases as the spheromak temperature increases, perhaps accounting for the ''voltage sag'' observed in some experiments, and a tendency toward a constant ratio of field to current, B ∝ I, or I TOR ∼ I. Program implications are discussed

  16. A Unified Impedance Model of Voltage-Source Converters with Phase-Locked Loop Effect

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Harnefors, Lennart; Blaabjerg, Frede

    2016-01-01

    This paper proposes a unified impedance model for analyzing the effect of Phase-Locked Loop (PLL) on the stability of grid-connected voltage-source converters. In the approach, the dq-frame impedance model is transformed into the stationary αβ-frame by means of complex transfer functions...... and complex space vectors, which not only predicts the stability impact of the PLL, but reveals also its frequency coupling effect in the phase domain. Thus, the impedance models previously developed in the different domains can be unified. Moreover, the impedance shaping effects of PLL are structurally...... characterized for the current control in the rotating dq-frame and the stationary αβ-frame. Case studies based on the unified impedance model are presented, which are then verified in the time-domain simulations and experiments. The results closely correlate with the impedance-based analysis....

  17. Impedance technique for measuring dielectrophoretic collection of microbiological particles

    CERN Document Server

    Allsopp, D W E; Brown, A P; Betts, W B

    1999-01-01

    Measurement of the impedance change resulting from the collection of microbiological particles at coplanar electrodes is shown to be an effective and potentially quantitative method of detecting dielectrophoresis. Strong correlations between the frequency-dependent dielectrophoretic collection characteristics measured by impedance change and those observed using an established counting method based on image analysis have been obtained for Escherichia coli. In addition it is shown that the new electrical method can be used to sense dielectrophoretic collection of 19 nm diameter latex beads, particles too small to be resolved by conventional optical detection systems. (author)

  18. VLF surface-impedance modelling techniques for coal exploration

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, G.; Thiel, D.; O' Keefe, S. [Central Queensland University, Rockhampton, Qld. (Australia). Faculty of Engineering and Physical Systems

    2000-10-01

    New and efficient computational techniques are required for geophysical investigations of coal. This will allow automated inverse analysis procedures to be used for interpretation of field data. In this paper, a number of methods of modelling electromagnetic surface impedance measurements are reviewed, particularly as applied to typical coal seam geology found in the Bowen Basin. At present, the Impedance method and the finite-difference time-domain (FDTD) method appear to offer viable solutions although both have problems. The Impedance method is currently slightly inaccurate, and the FDTD method has large computational demands. In this paper both methods are described and results are presented for a number of geological targets. 17 refs., 14 figs.

  19. Grid impedance detection via excitation of LCL-filter resonance

    DEFF Research Database (Denmark)

    Liserre, Marco; Blaabjerg, Frede; Teodorescu, Remus

    2005-01-01

    Inverters adopted in distributed power generation, active filter and UPS are often connected to the grid through an LCL-fiIter. The impedance of the LCL-fiIter has a typical frequency spectrum with a resonance peak. Hence the LCL-fiIter has to be damped in order to avoid instability. However...... the resonance of the LCL-fiIter can be also excited in a controlled way in order to individuate the resonance frequency in the spectrum (using for example the FFn. This paper proposes to use a controlled excitation to measure the grid impedance, since this one influences also the resonance frequency. This paper...... will address some possible limits, some solutions and some implementation issues (e.g. how to obtain a controlled resonance in the filter without damaging the system) in order to use the resonant peak for grid impedance detection. The analysis is validated both by simulations and experimental results....

  20. Road Impedance Model Study under the Control of Intersection Signal

    Directory of Open Access Journals (Sweden)

    Yunlin Luo

    2015-01-01

    Full Text Available Road traffic impedance model is a difficult and critical point in urban traffic assignment and route guidance. The paper takes a signalized intersection as the research object. On the basis of traditional traffic wave theory including the implementation of traffic wave model and the analysis of vehicles’ gathering and dissipating, the road traffic impedance model is researched by determining the basic travel time and waiting delay time. Numerical example results have proved that the proposed model in this paper has received better calculation performance compared to existing model, especially in flat hours. The values of mean absolute percentage error (MAPE and mean absolute deviation (MAD are separately reduced by 3.78% and 2.62 s. It shows that the proposed model has feasibility and availability in road traffic impedance under intersection signal.

  1. POTÊNCIA E CAPACIDADE ANAERÓBIA EM ATLETAS DE KARATE

    Directory of Open Access Journals (Sweden)

    Keith Sato Urbinati

    2011-01-01

    Full Text Available O objetivo do presente estudo foi verificar o nível de potência muscular, bem como a intensidade de esforço durante prova de potência e capacidade anaeróbia em atletas de Karate. Participaram do estudo treze karatekas especialistas em prova de kumitê (luta,sexo masculino, idade média de 20,7±3,79 anos. Realizou-se a avaliação de potência e capacidade anaeróbia (Wingate test, com coleta das variáveis fisiológicas:frequência cardíaca (FC, pressão arterial (PA e lactato sanguíneo (LAC de repouso, imediatamente após e em 5 min de recuperação. Para verificar se ocorrem diferenças nas variáveis fisiológicas durante o teste, realizou-se análise de variância, post hoc de Bonferronie (p?0,05. Verificou-se potência de pico(PP de 8,77 ± 0,99 W/kg-1, potência média (PM de 5,13± 0,49 W.kg-1 e % de fadiga de 50,5 ± 6,45%. Para as variáveis fisiológicas,a FC (F=9,79; p=0,00 pós-teste de Wingate foi estatisticamente maior e diferenteda FC de repouso e recuperação. Não foram encontradas diferenças nos níveis pressatórios e nas concentrações de LAC. Em relação aos valores de FC e LAC tais variáveis pós-teste não se apresentaram elevados. Os valores de potência anaeróbia estão de acordo com a necessidade da modalidade esportiva. Assim, verificou-se menores intensidades de esforço em teste de Wingate quando comparados a de situação real de competição. O nível de potência muscular parece estar adequado ao kumitê.

  2. Pumping slots: impedances and power losses

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S [Maryland Univ., College Park, MD (United States). Dept. of Physics

    1996-08-01

    Contributions of pumping slots to the beam coupling impedances and power losses in a B-factory ring are considered. While their leading contribution is to the inductive impedance, for high-intensity machines with short bunches like e{sup +}e{sup -} B-factories the real part of the impedance and related loss factors are also important. Using an analytical approach we calculate the coupling impedances and loss factors due to slots in a ring with an arbitrary cross section of the vacuum chamber. Effects of the slot tilt on the beam impedance are also considered, and restrictions on the tilt angle are derived from limitations on the impedance increase. The power leakage through the slots is discussed briefly. The results are applied to the KEK B-factory. (author)

  3. Numerical simulation on the energy spectrum of the electron beam generated by low-impedance diode and the influence of external magnetic field on diode impedance

    International Nuclear Information System (INIS)

    Liu Guozhi

    2003-01-01

    The energy spectrum of the electron beam generated by low-impedance diode and the influence of external magnetic field on the impedance of diode are studied numerically in this paper. The results show that the beam generated by the diode has an energy spread, even with constant applied voltage. Additionally, external magnetic field has great but reverse influence on the impedance of low-impedance diode, which is, according to the author's analysis, the result of the change of the electron's track due to external magnetic field. If the beam current is less than the critical one for self-pinch, the impedance will be constant with the variation of external magnetic field

  4. Corrosion Study Using Electrochemical Impedance Spectroscopy

    Science.gov (United States)

    Farooq, Muhammad Umar

    2003-01-01

    Corrosion is a common phenomenon. It is the destructive result of chemical reaction between a metal or metal alloy and its environment. Stainless steel tubing is used at Kennedy Space Center for various supply lines which service the orbiter. The launch pads are also made of stainless steel. The environment at the launch site has very high chloride content due to the proximity to the Atlantic Ocean. Also, during a launch, the exhaust products in the solid rocket boosters include concentrated hydrogen chloride. The purpose of this project was to study various alloys by Electrochemical Impedance Spectroscopy in corrosive environments similar to the launch sites. This report includes data and analysis of the measurements for 304L, 254SMO and AL-6XN in primarily neutral 3.55% NaCl. One set of data for 304L in neutral 3.55%NaCl + 0.1N HCl is also included.

  5. A compact broadband nonsynchronous noncommensurate impedance transformer

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Kim, Kseniya; Narenda, Kumar

    2012-01-01

    Nonsynchronous noncommensurate impedance transformers consist of a combination of high‐ and low‐impedance transmission lines. High‐impedance lines have narrow tracks in strip and microstrip technology, which allows for high flexibility and miniaturization of the layout in comparison...... to the traditional tapered line transformers. This flexibility of the broadband nonsynchronous noncommensurate impedance transformers is experimentally demonstrated in this article allowing the length reduction by almost three times. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1832–1835, 2012; View...

  6. On Impedance Spectroscopy of Supercapacitors

    Science.gov (United States)

    Uchaikin, V. V.; Sibatov, R. T.; Ambrozevich, A. S.

    2016-10-01

    Supercapacitors are often characterized by responses measured by methods of impedance spectroscopy. In the frequency domain these responses have the form of power-law functions or their linear combinations. The inverse Fourier transform leads to relaxation equations with integro-differential operators of fractional order under assumption that the frequency response is independent of the working voltage. To compare long-term relaxation kinetics predicted by these equations with the observed one, charging-discharging of supercapacitors (with nominal capacitances of 0.22, 0.47, and 1.0 F) have been studied by means of registration of the current response to a step voltage signal. It is established that the reaction of devices under study to variations of the charging regime disagrees with the model of a homogeneous linear response. It is demonstrated that relaxation is well described by a fractional stretched exponent.

  7. Electrical impedance tomography of electrolysis.

    Directory of Open Access Journals (Sweden)

    Arie Meir

    Full Text Available The primary goal of this study is to explore the hypothesis that changes in pH during electrolysis can be detected with Electrical Impedance Tomography (EIT. The study has relevance to real time control of minimally invasive surgery with electrolytic ablation. To investigate the hypothesis, we compare EIT reconstructed images to optical images acquired using pH-sensitive dyes embedded in a physiological saline agar gel phantom treated with electrolysis. We further demonstrate the biological relevance of our work using a bacterial E.Coli model, grown on the phantom. The results demonstrate the ability of EIT to image pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E.coli model. The results are promising, and invite further experimental explorations.

  8. Impedance and instability threshold estimates in the main injector I

    International Nuclear Information System (INIS)

    Martens, M.A.; Ng, K.Y.

    1994-03-01

    One of the important considerations in the design of the Main Injector is the beam coupling impedances in the vacuum chamber and the stability of the beam. Along with the higher intensities comes the possibility of instabilities which lead to growth in beam emittances and/or the loss of beam. This paper makes estimations of the various impedances and instability thresholds based on impedance estimations and measurements. Notably missing from this paper is any analysis of transition crossing and its potential limitations on beam intensity and beam emittance. Future work should consider this issue. The body of the work contains detailed analysis of the various impedance estimations and instability threshold calculations. The calculations are based on the Main Injector beam intensity of 6 x 10 10 protons per bunch, 95% normalized transverse emittances of 20π mm-mrad, and 95% normalized longitudinal emittance of 0.1 eV-s at 8.9 GeV injection energy and 0.25 eV-s at 150 GeV flattop energy. The conclusions section summarizes the results in the paper and is meant to be readable by itself without referring to the rest of the paper. Also in the conclusion section are recommendations for future investigations

  9. Quantification of coating aging using impedance measurements

    NARCIS (Netherlands)

    Westing, E.P.M. van; Weijde, D.H. van der; Vreijling, M.P.W.; Ferrari, G.M.; Wit, J.H.W. de

    1998-01-01

    This chapter shows the application results of a novel approach to quantify the ageing of organic coatings using impedance measurements. The ageing quantification is based on the typical impedance behaviour of barrier coatings in immersion. This immersion behaviour is used to determine the limiting

  10. Impedance of a slotted-pipe kicker

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Feng [Academia Sinica, Beijing, BJ (China). Inst. of High Energy Physics

    1996-08-01

    This paper introduces the principle of a new slotted kicker simply, which is made by using vacuum pipe itself with proper slits as current conductors, and then, presents a rough estimation of its longitudinal and transverse impedance, respectively. Calculation shows that its impedance is reduced significantly compared to our present air-coil kicker. (author)

  11. impedance calculations of induction machine rotor conductors.

    African Journals Online (AJOL)

    Dr Obe

    computed. The parallel R-L network shown in figure 3 is used in the modeling of the rotor bars. The network total impedance is given by,. (19). Where,. 5. simulation Results. MATLAB m-file for the calculation of the total impedance of the rectangular and trapezoidal rotor bars is developed [10]. The parameters of the bars.

  12. Impedance of Surface Footings on Layered Ground

    DEFF Research Database (Denmark)

    Andersen, Lars; Clausen, Johan Christian

    2005-01-01

    is discussed. Based on the Green's function for a stratified half-space, the impedance of a surface footing with arbitrary shape is computed. A wind turbine foundation is analysed in the frequency range 0 to 3 Hz. Analyses show that soil stratification may lead to a significant changes in the impedance related...

  13. Impedance of Surface Footings on Layered Ground

    DEFF Research Database (Denmark)

    Andersen, Lars; Clausen, Johan

    2008-01-01

    is discussed. Based on the Green's function for a stratified half-space, the impedance of a surface footing with arbitrary shape is computed. A wind turbine foundation is analysed in the frequency range 0-3 Hz. Analyses show that soil stratification may lead to significant changes in the impedance related...

  14. Quadratic Boost A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Chub, Andrii

    2016-01-01

    A novel quadratic boost A-source impedance network is proposed to realize converters that demand very high voltage gain. To satisfy the requirement, the network uses an autotransformer where the obtained gain is quadratically dependent on the duty ratio and is unmatched by any existing impedance...

  15. Impedance interactions in bidirectional cascaded converter

    DEFF Research Database (Denmark)

    Tian, Yanjun; Loh, Poh Chiang; Chen, Zhe

    2016-01-01

    A cascaded converter is built by connecting one elementary converter to another. Output impedance of one converter will therefore interact with input impedance of the other converter. This interaction will change when power flow reverses. To compare this difference, an investigation is performed...

  16. Possibilities of electrical impedance tomography in gynecology

    International Nuclear Information System (INIS)

    Trokhanova O V; Chijova Y A; Okhapkin M B; Korjenevsky A V; Tuykin T S

    2013-01-01

    The paper describes results of comprehensive EIT diagnostics of mammary glands and cervix. The data were obtained from examinations of 170 patients by EIT system MEM (multi-frequency electrical impedance mammograph) and EIT system GIT (gynecological impedance tomograph). Mutual dependence is discussed.

  17. Time-domain representation of frequency-dependent foundation impedance functions

    Science.gov (United States)

    Safak, E.

    2006-01-01

    Foundation impedance functions provide a simple means to account for soil-structure interaction (SSI) when studying seismic response of structures. Impedance functions represent the dynamic stiffness of the soil media surrounding the foundation. The fact that impedance functions are frequency dependent makes it difficult to incorporate SSI in standard time-history analysis software. This paper introduces a simple method to convert frequency-dependent impedance functions into time-domain filters. The method is based on the least-squares approximation of impedance functions by ratios of two complex polynomials. Such ratios are equivalent, in the time-domain, to discrete-time recursive filters, which are simple finite-difference equations giving the relationship between foundation forces and displacements. These filters can easily be incorporated into standard time-history analysis programs. Three examples are presented to show the applications of the method.

  18. Wave impedance selection for passivity-based bilateral teleoperation

    Science.gov (United States)

    D'Amore, Nicholas John

    instantaneous conditions encountered. A Lyapunov-like analysis is presented demonstrating that time variation in wave impedance will not violate the passivity of the system. Experimental trials, both in simulation and on a haptic feedback device, are presented validating the technique. Consideration is also given to the case of an uncertain environment, in which an a priori impedance choice may not be possible.

  19. Fractional Order Element Based Impedance Matching

    KAUST Repository

    Radwan, Ahmed Gomaa

    2014-06-24

    Disclosed are various embodiments of methods and systems related to fractional order element based impedance matching. In one embodiment, a method includes aligning a traditional Smith chart (|.alpha.|=1) with a fractional order Smith chart (|.alpha.|.noteq.1). A load impedance is located on the traditional Smith chart and projected onto the fractional order Smith chart. A fractional order matching element is determined by transitioning along a matching circle of the fractional order Smith chart based at least in part upon characteristic line impedance. In another embodiment, a system includes a fractional order impedance matching application executed in a computing device. The fractional order impedance matching application includes logic that obtains a first set of Smith chart coordinates at a first order, determines a second set of Smith chart coordinates at a second order, and determines a fractional order matching element from the second set of Smith chart coordinates.

  20. Impedance of finite length resistive cylinder

    Directory of Open Access Journals (Sweden)

    S. Krinsky

    2004-11-01

    Full Text Available We determine the impedance of a cylindrical metal tube (resistor of radius a, length g, and conductivity σ attached at each end to perfect conductors of semi-infinite length. Our main interest is in the asymptotic behavior of the impedance at high frequency (k≫1/a. In the equilibrium regime, ka^{2}≪g, the impedance per unit length is accurately described by the well-known result for an infinite length tube with conductivity σ. In the transient regime, ka^{2}≫g, where the contribution of transition radiation arising from the discontinuity in conductivity is important, we derive an analytic expression for the impedance and compute the short-range wakefield. The analytic results are shown to agree with numerical evaluation of the impedance.

  1. Business English in the Eyes of Economics and Management Students at the University of Białystok

    Directory of Open Access Journals (Sweden)

    Dzięcioł-Pędich Agnieszka

    2014-09-01

    Full Text Available According to the regulations of the Polish Ministry of Science and Higher Education, university graduates should have to know a foreign language at B2 level, as described in The Common European Framework of Reference, and they should know its specialized variety. These are the only recommendations concerning general language courses and their specialized varieties. It is up to schools of foreign languages or other institutions providing language courses for institutions of higher education to determine requirements concerning language for specific purposes. However, students are rarely asked to contribute to the development of curricula and syllabi. This article presents the results of a survey conducted among students of Economics and Management at the University of Białystok. The survey was devoted to students’ perceptions of Business English in English courses conducted by the School of Foreign Languages at the University of Białystok. The aim of the survey was to answer the following questions:

  2. Impedance Changes Indicate Proximal Ventriculoperitoneal Shunt Obstruction In Vitro.

    Science.gov (United States)

    Basati, Sukhraaj; Tangen, Kevin; Hsu, Ying; Lin, Hanna; Frim, David; Linninger, Andreas

    2015-12-01

    Extracranial cerebrospinal fluid (CSF) shunt obstruction is one of the most important problems in hydrocephalus patient management. Despite ongoing research into better shunt design, robust and reliable detection of shunt malfunction remains elusive. The authors present a novel method of correlating degree of tissue ingrowth into ventricular CSF drainage catheters with internal electrical impedance. The impedance based sensor is able to continuously monitor shunt patency using intraluminal electrodes. Prototype obstruction sensors were fabricated for in-vitro analysis of cellular ingrowth into a shunt under static and dynamic flow conditions. Primary astrocyte cell lines and C6 glioma cells were allowed to proliferate up to 7 days within a shunt catheter and the impedance waveform was observed. During cell ingrowth a significant change in the peak-to-peak voltage signal as well as the root-mean-square voltage level was observed, allowing the impedance sensor to potentially anticipate shunt malfunction long before it affects fluid drainage. Finite element modeling was employed to demonstrate that the electrical signal used to monitor tissue ingrowth is contained inside the catheter lumen and does not endanger tissue surrounding the shunt. These results may herald the development of "next generation" shunt technology that allows prediction of malfunction before it affects patient outcome.

  3. Magnetotelluric impedance tensor analysis for identification of ...

    Indian Academy of Sciences (India)

    G Pavan Kumar

    2017-07-18

    Jul 18, 2017 ... The transverse geo-electric strike coincides with the prominent clustering of .... Unrotated apparent resistivity and phase curves for four sites along the profile. ..... The Bhuj earthquake: Tomographic evidence for fluids at.

  4. Tracking of electrochemical impedance of batteries

    Science.gov (United States)

    Piret, H.; Granjon, P.; Guillet, N.; Cattin, V.

    2016-04-01

    This paper presents an evolutionary battery impedance estimation method, which can be easily embedded in vehicles or nomad devices. The proposed method not only allows an accurate frequency impedance estimation, but also a tracking of its temporal evolution contrary to classical electrochemical impedance spectroscopy methods. Taking into account constraints of cost and complexity, we propose to use the existing electronics of current control to perform a frequency evolutionary estimation of the electrochemical impedance. The developed method uses a simple wideband input signal, and relies on a recursive local average of Fourier transforms. The averaging is controlled by a single parameter, managing a trade-off between tracking and estimation performance. This normalized parameter allows to correctly adapt the behavior of the proposed estimator to the variations of the impedance. The advantage of the proposed method is twofold: the method is easy to embed into a simple electronic circuit, and the battery impedance estimator is evolutionary. The ability of the method to monitor the impedance over time is demonstrated on a simulator, and on a real Lithium ion battery, on which a repeatability study is carried out. The experiments reveal good tracking results, and estimation performance as accurate as the usual laboratory approaches.

  5. The tourism potential of the commune Janów Podlaski and its evaluation of tourism appeal as compared to the administrative district of Biała Podlaska (Lublin voivodeship)

    Science.gov (United States)

    Skrzypczak, Andrzej; Chmielewska, Anna Beata

    2009-01-01

    The purpose of this thesis has been to evaluate tourism appeal of the commune of Janów Podlaski, as compared to the other communes in the administrative district of Biała Podlaska, and to analyse the recreational potential of the natural environment within the commune and it's present day infrastructure for tourism industry. For evaluation of the tourism attractiveness of the commune, based on comparative analysis, the method of synthetic measures was applied. The commune of Janów Podlaski belongs to one of the most attractive areas for tourists in the administrative district of Biała Podlaska. The attractiveness of the commune is associated with the Bug river, which flows across high-value landscapes and possess many ecological assets. Development of water tourism, however, is hindered by the fact that the Bug forms part of Poland's state border and it's water is rather polluted. Walking tourism in the commune of Janów Podlaski is encouraged owing to a well-developed and properly sing-posted networks of trails. The accommodation facilities are not evenly distributed as most of the rooms for tourists can be found in Janów Podlaski.

  6. Longitudinal beam instability due to the ring impedance at KEK's accelerator test facility damping ring

    International Nuclear Information System (INIS)

    Kim, Eun-San

    2003-01-01

    This paper shows the results of a numerical study of the impedance in the Accelerator Test Facility damping ring. The longitudinal impedance in the damping ring is shown to be inductive. It is shown that the total impedance |Z || /n| is 0.23 Ω and the inductance is L = 14 nH. In the extremely low emittance beam of the damping ring, bunch lengthening is caused by both the effects of potential-well distortion and intra-beam scattering. In this paper, the bunch-lengthening due to the ring impedance is numerically investigated, and the result shows qualitative agreement with the result of an analysis performed using the bunch-length measurement. With the calculated longitudinal impedance, the instability threshold in the damping ring is estimated to be a bunch population of 3.3 x 10 10 by using both a Vlasov equation approach and a multi-particle tracking method.

  7. Wearable impedance monitoring system for dialysis patients.

    Science.gov (United States)

    Bonnet, S; Bourgerette, A; Gharbi, S; Rubeck, C; Arkouche, W; Massot, B; McAdams, E; Montalibet, A; Jallon, P

    2016-08-01

    This paper describes the development and the validation of a prototype wearable miniaturized impedance monitoring system for remote monitoring in home-based dialysis patients. This device is intended to assess the hydration status of dialysis patients using calf impedance measurements. The system is based on the low-power AD8302 component. The impedance calibration procedure is described together with the Cole parameter estimation and the hydric volume estimation. Results are given on a test cell to validate the design and on preliminary calf measurements showing Cole parameter variations during hemodialysis.

  8. Identification of irradiated potatoes by impedance

    International Nuclear Information System (INIS)

    Singh, Rita; Singh, Antaryami; Wadhawan, A.K.

    1997-01-01

    The electrical impedance of potatoes irradiated at 60, 90, 150 and 1000 Gy was measured using various frequencies of alternating current. The impedance of the irradiated potatoes was higher than the unirradiated potatoes particularly in the frequency range of 100 Hz to 10 kHz. The ratio of the impedance at 5 kHz to that at 50 Hz (Z5k/Z50) was found to be the best indicator for detection of radiation treatment. (author). 4 refs., 2 figs

  9. Electrical Impedance Measurements of PZT Nanofiber Sensors

    Directory of Open Access Journals (Sweden)

    Richard Galos

    2017-01-01

    Full Text Available Electrical impedance measurements of PZT nanofiber sensors were performed using a variety of methods over a frequency spectrum ranging from DC to 1.8 GHz. The nanofibers formed by electrospinning with diameters ranging from 10 to 150 nm were collected and integrated into sensors using microfabrication techniques. Special matching circuits with ultrahigh input impedance were fabricated to produce low noise, measurable sensor outputs. Material properties including resistivity and dielectric constant are derived from the impedance measurements. The resulting material properties are also compared with those of individual nanofibers being tested using conductive AFM and Scanning Conductive Microscopy.

  10. Small-signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Knott, Arnold; Iversen, Niels Elkjær

    2014-01-01

    Specifying the performance of audio ampliers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterised by the mechanical resonance between the mass of the diaphragm and the compliance of its' suspension which vary from...... driver to driver. Therefore a loudspeaker emulator capable of adjusting its' impedance to a given driver is in need for measurement purposes. This paper proposes a loudspeaker emulator circuit for small signals. Simulations and experimental results are compared and show that it is possible to emulate...... the loudspeaker impedance with an electric circuit and that its' resonance frequency can be changed by tuning two resistors....

  11. RHIC ABORT KICKER WITH REDUCED COUPLING IMPEDANCE

    International Nuclear Information System (INIS)

    HAHN, H.; DAVINO, D.

    2002-01-01

    Kicker magnets typically represent the most important contributors to the transverse impedance budget of accelerators and storage rings. Methods of reducing the impedance value of the SNS extraction kicker presently under construction and, in view of a future performance upgrade, that of the RHIC abort kicker have been thoroughly studied at this laboratory. In this paper, the investigation of a potential improvement from using ferrite different from the BNL standard CMD5005 is reported. Permeability measurements of several ferrite types have been performed. Measurements on two kicker magnets using CMD5005 and C2050 suggest that the impedance of a magnet without external resistive damping, such as the RHIC abort kicker, would benefit

  12. SPATIAL VARIABILITY OF PEDOZEMS MECHANICAL IMPEDANCE

    Directory of Open Access Journals (Sweden)

    Zhukov A.V.

    2013-04-01

    Full Text Available We studied the spatial variability of pedozem mechanical impedance in ResearchRemediation Center of the Dnipropetrovsk State Agrarian University in Ordzhonikidze. Thestatistical distribution of the soil mechanical impedance within the studied area is characterized by deviation from the normal law in 0–10 and 30–50 cm layers from the surface. 2D and 3D modeling shows the structural design of the soil as locations of high mechanical impedance which found in the soils with less hardness.

  13. Sound Propagation An impedance Based Approach

    CERN Document Server

    Kim, Yang-Hann

    2010-01-01

    In Sound Propagation: An Impedance Based Approach , Professor Yang-Hann Kim introduces acoustics and sound fields by using the concept of impedance. Kim starts with vibrations and waves, demonstrating how vibration can be envisaged as a kind of wave, mathematically and physically. One-dimensional waves are used to convey the fundamental concepts. Readers can then understand wave propagation in terms of characteristic and driving point impedance. The essential measures for acoustic waves, such as dB scale, octave scale, acoustic pressure, energy, and intensity, are explained. These measures are

  14. Impedance imaging in core analysis. Imaging of phase distributions in samples of natural cores of North Sea chalk containing conducting as well as non-conducting fluids. Part: 1-3

    Energy Technology Data Exchange (ETDEWEB)

    Laursen, S. [DTU, Inst. for Kemi (Denmark)] Moeller Nielsen, C. [DTU, Inst. for Energiteknik (Denmark)

    1997-12-31

    The present report documents the efforts to develop an impedance method for determining the distribution of the water saturation in a chalk core sample. Measurement of this distribution during a displacement process will make it possible to make numerical simulations of the process which may in turn reveal important rock parameters. The impedance method is one among other methods to determine saturation profiles in a research programme on rock parameters with participants from Danmarks Tekniske Universitet, DTU, and Danmarks og Groenlands Geologiske Undersoegelse, GEUS. The other methods investigated are nmr-scanning and {gamma}-logging. (au)

  15. Intracardiac impedance response during acute AF internal cardioversion using novel rectilinear and capacitor-discharge waveforms.

    Science.gov (United States)

    Rababah, A S; Walsh, S J; Manoharan, G; Walsh, P R; Escalona, O J

    2016-07-01

    Intracardiac impedance (ICI) is a major determinant of success during internal cardioversion of atrial fibrillation (AF). However, there have been few studies that have examined the dynamic behaviour of atrial impedance during internal cardioversion in relation to clinical outcome. In this study, voltage and current waveforms captured during internal cardioversion of acute AF in ovine models using novel radiofrequency (RF) generated low-tilt rectilinear and conventional capacitor-discharge based shock waveforms were retrospectively analysed using a digital signal processing algorithm to investigate the dynamic behaviour of atrial impedance during cardioversion. The algorithm was specifically designed to facilitate the simultaneous analysis of multiple impedance parameters, including: mean intracardiac impedance (Z M), intracardiac impedance variance (ICIV) and impedance amplitude spectrum area (IAMSA) for each cardioversion event. A significant reduction in ICI was observed when comparing two successive shocks of increasing energy where cardioversion outcome was successful. In addition, ICIV and IAMSA variables were found to inversely correlate to the magnitude of energy delivered; with a stronger correlation found to the former parameter. In conclusion, ICIV and IAMSA have been evidenced as two key dynamic intracardiac impedance variables that may prove useful in better understanding of the cardioversion process and that could potentially act as prognostic markers with respect to clinical outcome.

  16. Bioelectrical impedance vector distribution in the first year of life.

    Science.gov (United States)

    Savino, Francesco; Grasso, Giulia; Cresi, Francesco; Oggero, Roberto; Silvestro, Leandra

    2003-06-01

    We assessed the bioelectrical impedance vector distribution in a sample of healthy infants in the first year of life, which is not available in literature. The study was conducted as a cross-sectional study in 153 healthy Caucasian infants (90 male and 63 female) younger than 1 y, born at full term, adequate for gestational age, free from chronic diseases or growth problems, and not feverish. Z scores for weight, length, cranial circumference, and body mass index for the study population were within the range of +/-1.5 standard deviations according to the Euro-Growth Study references. Concurrent anthropometrics (weight, length, and cranial circumference), body mass index, and bioelectrical impedance (resistance and reactance) measurements were made by the same operator. Whole-body (hand to foot) tetrapolar measurements were performed with a single-frequency (50 kHz), phase-sensitive impedance analyzer. The study population was subdivided into three classes of age for statistical analysis: 0 to 3.99 mo, 4 to 7.99 mo, and 8 to 11.99 mo. Using the bivariate normal distribution of resistance and reactance components standardized by the infant's length, the bivariate 95% confidence limits for the mean impedance vector separated by sex and age groups were calculated and plotted. Further, the bivariate 95%, 75%, and 50% tolerance intervals for individual vector measurements in the first year of life were plotted. Resistance and reactance values often fluctuated during the first year of life, particularly as raw measurements (without normalization by subject's length). However, 95% confidence ellipses of mean vectors from the three age groups overlapped each other, as did confidence ellipses by sex for each age class, indicating no significant vector migration during the first year of life. We obtained an estimate of mean impedance vector in a sample of healthy infants in the first year of life and calculated the bivariate values for an individual vector (95%, 75%, and 50

  17. An Annotated And Illustrated Catalogue Of Polypores (Agaricomycetes Of The Białowieża Forest (NE Poland

    Directory of Open Access Journals (Sweden)

    Karasiński Dariusz

    2015-12-01

    Full Text Available The Białowieża Forest (BF is one of the best-preserved lowland deciduous and mixed forest complexes in Europe, rich in diverse fungi. This paper summarizes what is known about the poroid fungi of the Polish part of the Białowieża Forest, based on literature data, a re-examination of herbarium materials, and the authors’ studies from 1990–2014. An annotated catalogue of polypores recorded in the forest is presented, including 80 genera with 210 species. All literature and herbarium records are enumerated, and 160 species are illustrated with color pictures. Fourteen species previously reported in the literature have uncertain status because they lack voucher specimens and were not confirmed in recent field studies. Antrodiella subradula (Pilát Niemelä & Miettinen, previously known from Asia, is reported for the first time from Europe. Fourteen species are newly reported from the Białowieża Forest (mainly from Białowieża National Park, including 8 species with first records in Poland (Antrodia hyalina Spirin, Miettinen & Kotir., Antrodia infirma Renvall & Niemelä, Antrodiella subradula, Junghuhnia fimbriatella (Peck Ryvarden, Postia folliculocystidiata (Kotl. & Vampola Niemelä & Vampola, Postia minusculoides (Pilát ex Pilát Boulet, Skeletocutis chrysella Niemelä, Skeletocutis papyracea A. David, and 6 species reported previously from other localities in Poland [Antrodiella faginea Vampola & Pouzar, Dichomitus campestris (Quél. Domański & Orlicz, Loweomyces fractipes (Berk. & M. A. Curtis Jülich, Oxyporus latemarginatus (Durieu & Mont. Donk, Perenniporia narymica (Pilát Pouzar, Phellinus nigricans (Fr. P. Karst.]. Several very rare European polypores already reported from the Białowieża Forest in the 20th century, such as Antrodia albobrunnea (Romell Ryvarden, Antrodiella foliaceodentata (Nikol. Gilb. & Ryvarden, Buglossoporus pulvinus (Pers. Donk, Dichomitus albidofuscus (Domański Domański and Gelatoporia subvermispora

  18. Fast FPGA Implementation of an Original Impedance Analyser

    Directory of Open Access Journals (Sweden)

    Abdulrahman HAMED

    2011-02-01

    Full Text Available This article describes in detail the design and rapid prototyping of an embedded impedance analyzer. The measurement principle is based on the feedback control of the excitation voltage VD during a fast frequency sweeping. This function is carried out by a high precision synthesizer whose output resistance RG is digitally adjustable. Real and imaginary parts of the dipole impedance are determined from RG and the phase of VD. The digital architecture design uses the hardware-in-the-loop simulation in which the dipole is modeled using an RLC parallel circuit and a Butterworth Van Dyke structure. All digital functions are implemented on a Stratix II FPGA board with a 100 MHz frequency clock. The parameters taken into account are the frequency range (0 to 5 MHz, speed and resolution of the analysis and the quality factor of the resonant dipole. To reduce the analysis duration, the frequency sweeping rate is adjusted in real time.

  19. Theory for electrochemical impedance spectroscopy of ...

    Indian Academy of Sciences (India)

    Shweta Dhillon

    generalize phenomenological theory for the Randles-Ershler admittance at the electrode with double layer capacitance ..... impedance (equation 12) curves accounting for the elec- ..... R.K. thanks University of Delhi for the financial support.

  20. Battery impedance spectroscopy using bidirectional grid connected

    Indian Academy of Sciences (India)

    Keywords. Impedance spectroscopy; grid connection; battery converter; state of charge; health monitoring ... The converter is grid connected and controlled to operate at unity power factor. Additional ... Sadhana. Current Issue : Vol. 43, Issue 6.

  1. Impedance and collective effects in the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Gareyte, J [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    After a review of the main LHC parameters, and a brief description of the RF and vacuum systems, the coupling impedances of the main machine elements are given, as well as the resulting thresholds for instabilities. (author)

  2. Electrochemical Impedance Studies of SOFC Cathodes

    DEFF Research Database (Denmark)

    Hjelm, Johan; Søgaard, Martin; Wandel, Marie

    2007-01-01

    Mixed ion- and electron-conducting composite electrodes consisting of doped ceria and perovskite have been studied by electrochemical impedance spectroscopy (EIS) at different temperatures and oxygen partial pressures. This paper aims to describe the different contributions to the polarisation...

  3. Loudspeaker impedance emulator for multi resonant systems

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2015-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterised by its electrical, mechanical and acoustical properties. Therefore a loudspeaker emulator capable of adjusting...... its impedance to that of a given loudspeaker is desired for measurement purposes. An adjustable RLC based emulator is implemented with switch controlled capacitors, air gap controlled inductors and potentiometers. Calculations and experimental results are compared and show that it is possible...... to emulate the loudspeaker impedance infinite baffle-, closed box- and the multi resonant vented box-loudspeaker by tuning the component values in the proposed circuit. Future work is outlined and encourage that the proposed impedance emulator is used as part of a control circuit in a switch-mode based...

  4. Modeling degradation in SOEC impedance spectra

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard; Hauch, Anne; Knibbe, Ruth

    2013-01-01

    Solid oxide cell (SOC) performance is limited by various processes. One way to investigate these processes is by electrochemical impedance spectroscopy. In order to quantify and characterize the processes, an equivalent circuit can be used to model the SOC impedance spectra (IS). Unfortunately......, the optimal equivalent circuit is often unknown and to complicate matters further, several processes contribute to the SOC impedance - making detailed process characterization difficult. In this work we analyze and model a series of IS measured during steam electrolysis operation of an SOC. During testing......, degradation is only observed in the Ni/YSZ electrode and not in the electrolyte or the LSM/YSZ electrode. A batch fit of the differences between the IS shows that a modified Gerischer element provides a better fit to the Ni/YSZ electrode impedance than the frequently used RQ element - albeit neither...

  5. Estimating the short-circuit impedance

    DEFF Research Database (Denmark)

    Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad

    1997-01-01

    A method for establishing a complex value of the short-circuit impedance from naturally occurring variations in voltage and current is discussed. It is the symmetrical three phase impedance at the fundamental grid frequency there is looked for. The positive sequence components in voltage...... and current are derived each period, and the short-circuit impedance is estimated from variations in these components created by load changes in the grid. Due to the noisy and dynamic grid with high harmonic distortion it is necessary to threat the calculated values statistical. This is done recursively...... through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...

  6. New Magnetically Coupled Impedance (Z-) Source Networks

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang

    2016-01-01

    Various Magnetically Coupled Impedance Source (MCIS) networks have been proposed in the literature for increasing voltage gain and modulation index simultaneously, while reducing the number of passive components used in the converter. However, applications of such networks have been limited...

  7. Fractional Order Element Based Impedance Matching

    KAUST Repository

    Radwan, Ahmed Gomaa; Salama, Khaled N.; Shamim, Atif

    2014-01-01

    Disclosed are various embodiments of methods and systems related to fractional order element based impedance matching. In one embodiment, a method includes aligning a traditional Smith chart (|.alpha.|=1) with a fractional order Smith chart (|.alpha

  8. Synanthropization of dendroflora near main roads in Białystok (NE Poland

    Directory of Open Access Journals (Sweden)

    Łaska Grażyna

    2015-06-01

    Full Text Available The aim of the study was to analyze the species composition of the dendroflora near four main roads in the city of Białystok, taking into regard their geographical and historical origin. The wildlife inventory was conducted in the vegetation season of 2011. The inventory revealed presence of a total of 837 trees and bushes representing 36 species and 18 families. The most abundant trees were those from the family Aceraceae (63.8%, while the most abundant bushes were those representing Rosaceae (48.9%. The contribution of native species (65.7% was found to be about twice as high as that of alien ones (34.3%. The dominant species among the native trees was Acer platanoides L., while the principal bush species was Crataegus monogyna Jacq. The alien tree species were most commonly represented by Acer negundo L., and bushes - by Ligustrum vulgare L. Spontaneously settled trees and bushes were clearly dominant (59.9% over those originating from plantations (40.1%. Among the native species of local origin, the prevailing species were synanthropic spontaneophytes (52%, including Acer platanoides and Tilia cordata Mill. Anthropophytes were more abundantly represented by diaphytes (22.7%, followed by kenophytes (10.4%. The most abundant species among diaphytes was Ligustrum vulgare, and among kenophytes - Acer negundo.

  9. Compensating for evanescent modes and estimating characteristic impedance in waveguide acoustic impedance measurements

    DEFF Research Database (Denmark)

    Nørgaard, Kren Rahbek; Fernandez Grande, Efren

    2017-01-01

    The ear-canal acoustic impedance and reflectance are useful for assessing conductive hearing disorders and calibrating stimulus levels in situ. However, such probe-based measurements are affected by errors due to the presence of evanescent modes and incorrect estimates or assumptions regarding...... characteristic impedance. This paper proposes a method to compensate for evanescent modes in measurements of acoustic impedance, reflectance, and sound pressure in waveguides, as well as estimating the characteristic impedance immediately in front of the probe. This is achieved by adjusting the characteristic...... impedance and subtracting an acoustic inertance from the measured impedance such that the non-causality in the reflectance is minimized in the frequency domain using the Hilbert transform. The method is thus capable of estimating plane-wave quantities of the sought-for parameters by supplying only...

  10. Theoretical interpretation of Warburg's impedance in unsupported electrolytic cells.

    Science.gov (United States)

    Barbero, G

    2017-12-13

    We discuss the origin of Warburg's impedance in unsupported electrolytic cells containing only one group of positive and one group of negative ions. Our analysis is based on the Poisson-Nernst-Planck model, where the generation-recombination phenomenon is neglected. We show that to observe Warburg-like impedance the diffusion coefficient of the positive ions has to differ from that of the negative ones, and furthermore the electrodes have to be not blocking. We assume that the non-blocking properties of the electrodes can be described by means of an Ohmic model, where the charge exchange between the cell and the external circuit is described by means of an electrode conductivity. For simplicity we consider a symmetric cell. However, our analysis can be easily generalized to more complicated situations, where the cell is not symmetric and the charge exchange is described by the Chang-Jaffe model, or by a linearized version of the Butler-Volmer equation. Our analysis allows justification of the expression for Warburg's impedance proposed previously by several groups, based on wrong assumptions.

  11. Journal and Wave Bearing Impedance Calculation Software

    Science.gov (United States)

    Hanford, Amanda; Campbell, Robert

    2012-01-01

    The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

  12. Longitudinal coupling impedance of a hole in the accelerator beam pipe

    International Nuclear Information System (INIS)

    Chae, Yong-Chul.

    1993-12-01

    In the design of modern accelerators, an accurate estimate of coupling impedance is very important. The sources which give rise to coupling impedance are the geometric discontinuities in the accelerator beam pipe. In various discontinuities such as RF cavities, bellows, and collimators, the coupling impedance of the holes has not been well understood. Although coupling impedance can be obtained in general from the Fourier transform of the corresponding wake potential which may be obtained numerically, this is time consuming and requires a large amount of computer storage when applied to a small dimension of a discontinuity in a typical beam pipe, often imposing a fundamental limitation of the numerical approach. More fundamentally, however, numerical calculation does not have the predictive power because of limited understanding of how the coupling impedance of a hole should behave over a wide frequency range. This question was studied by developing a theoretical analysis based on a variational method. An analytical formula for the coupling impedance of a hole is developed in this work using a variational method. The result gives good qualitative agreements with the coupling impedances evaluated numerically from the Fourier transform of the wake potential which is obtained from the computer code MAFIA-T3. The author shows that the coupling impedance of a hole behaves quite similar to the impedance of an RLC-resonator circuit. Important parameters used to describe such a resonator circuit are the resonant frequency and bandwidth. The author provides a theoretical insight on how to parameterize properly the numerical impedance of a hole when data exhibit complicated dependence on frequency. This is possible because one can show that the parameters are a function of the dimensionless quantity kd alone, with k the free-space wave number and d the radius of hole

  13. [HAS budget impact analysis guidelines: A new decision-making tool].

    Science.gov (United States)

    Ghabri, Salah; Poullié, Anne-Isabelle; Autin, Erwan; Josselin, Jean-Michel

    2017-10-02

    Budget impact analysis (BIA) provides short and medium-term estimates on changes in budgets and resources resulting from the adoption of new health interventions. The objective of this article is to present the main messages of the newly developed French National Authority for Health (HAS) guidelines on budget impact analysis : issues, recommendations and perspectives. The HAS guidelines development process was based on data derived from a literature review on BIA (search dates : January 2000 to June 2016), an HAS retrospective investigation, a public consultation, international expert advice, and approval from the HAS Board and the Economic and Public Health Evaluation Committee. Based on its research findings, HAS developed its first BIA guidelines, which include recommendations on the following topics : BIA definition, perspective, populations, time horizon, compared scenarios, budget impact models, costing, discounting, choice of clinical data, reporting of results and uncertainty analysis. The HAS BIA guidelines are expected to enhance the usefulness of BIA as an essential part of a comprehensive economic assessment of healthcare interventions, which itself includes cost-effectiveness analysis and equity of access to healthcare.

  14. Impedance matching wireless power transmission system for biomedical devices.

    Science.gov (United States)

    Lum, Kin Yun; Lindén, Maria; Tan, Tian Swee

    2015-01-01

    For medical application, the efficiency and transmission distance of the wireless power transfer (WPT) are always the main concern. Research has been showing that the impedance matching is one of the critical factors for dealing with the problem. However, there is not much work performed taking both the source and load sides into consideration. Both sides matching is crucial in achieving an optimum overall performance, and the present work proposes a circuit model analysis for design and implementation. The proposed technique was validated against experiment and software simulation. Result was showing an improvement in transmission distance up to 6 times, and efficiency at this transmission distance had been improved up to 7 times as compared to the impedance mismatch system. The system had demonstrated a near-constant transfer efficiency for an operating range of 2cm-12cm.

  15. Bench measurements of coupling impedance of AGS Booster components

    International Nuclear Information System (INIS)

    Ratti, A.; Shea, T.J.

    1991-01-01

    Quantifying instability thresholds for modern synchrotrons and storage rings requires some knowledge of the accelerator's coupling impedance. To this end, the wire technique has been implemented to measure the longitudinal coupling impedance of AGS Booster devices. The techniques are being refined to allow measurement of RHIC devices at higher frequencies. All the measurements are performed using an HP 8753 Network Analyzer controlled via GPIB by a Macintosh computer. The computer provides an environment for automated data acquisition, data analysis, and report generation. Resistive matches between the 50ω analyzer cables and the 300ω pipe-and-wire structure allow the use of a simple response calibration in the measurement of S21 to 400MHz. Results from ferrite loaded rf cavities, position monitors and kickers are presented. 4 refs., 4 figs

  16. Impedance function of a group of vertical piles

    International Nuclear Information System (INIS)

    Wolf, J.P.; Arx, G.A. von

    1978-01-01

    Impedance and transfer functions of a group of vertical piles located in any desired configuration in plan in a horizontally stratified soil layer are derived. Hysteretic and radiation damping are accounted for. The method separates the piles and the soil, introducing unknown interaction forces. The total flexibility matrix of the soil is constructed, superposing the (complex) flexibility coefficients caused by the interaction forces of a single pile only. The dependence of the impedance and transfer functions on the oscllating frequency for foundations with different numbers of piles is investigated. Pile-soil-pile interaction is shown to be very important for all modes of vibration. The procedure is used in the seismic analysis of a reactor building. (Author)

  17. VISUALIZATION OF BIOLOGICAL TISSUE IMPEDANCE PARAMETERS

    Directory of Open Access Journals (Sweden)

    V. I. Bankov

    2016-01-01

    Full Text Available Objective. Investigation the opportunity for measurement of biological tissue impedance to visualize its parameters.Materials and methods. Studies were undertook on the experimental facility, consists of registrating measuring cell, constructed from flat inductors system, formed in oscillatory circuit, herewith investigated biological tissue is the part of this oscillatory circuit. An excitation of oscillatory circuit fulfilled by means of exciter inductor which forms impulse complex modulated electromagnetic field (ICM EMF. The measurement process and visualizations provided by set of certificated instruments: a digital oscillograph AKTAKOM ADS-2221MV, a digital generator АКТАКОМ AWG-4150 (both with software and a gauge RLC E7-22. Comparative dynamic studies of fixed volume and weight pig’s blood, adipose tissue, muscular tissue impedance were conducted by contact versus contactless methods. Contactless method in contrast to contact method gives opportunity to obtain the real morphological visualization of biological tissue irrespective of their nature.Results. Comparison of contact and contactless methods of impedance measurement shows that the inductance to capacitance ratio X(L / X(C was equal: 17 – for muscular tissue, 4 – for blood, 1 – for adipose tissue. It demonstrates the technical correspondence of both impedance registration methods. If propose the base relevance of X (L and X (C parameters for biological tissue impedance so contactless measurement method for sure shows insulating properties of adipose tissue and high conductivity for blood and muscular tissue in fixed volume-weight parameters. Registration of biological tissue impedance complex parameters by contactless method with the help of induced ICM EMF in fixed volume of biological tissue uncovers the most important informative volumes to characterize morphofunctional condition of biological tissue namely X (L / X (C.Conclusion. Contactless method of biological

  18. Laboratory scale tests of electrical impedence tomography

    International Nuclear Information System (INIS)

    Binley, A; Daily, W; LaBredcque, D; Ramirez, A.

    1998-01-01

    Electrical impedance tomographs (magnitude and phase) of known, laboratory-scale targets are reported. Three methods are used to invert electrical impedance data and their tomographs compared. The first method uses an electrical resistance tomography (ERT) algonthm (designed for DC resistivity inversion) to perform impedance magnitude inversion and a linearized perturbation approach (PA) to invert the imaginary part. The second approximate method compares ERT magnitude inversions at two frequencies and uses the frequency effect (FE) to compute phase tomographs. The third approach, electrrcal impedance tomography (EIT), employs fully complex algebra to account for the real and imaginary components of electrical impedance data. The EIT approach provided useful magnitude and phase images for the frequency range of 0.0625 to 64 Hz; images for higher frequencies were not reliable. Comparisons of the ERT and EIT magnitude images show that both methods provided equivalent results for the water blank, copper rod and PVC rod targets. The EIT magnitude images showed better spatial resolutron for a sand-lead mixture target. Phase images located anomalies of both high and low contrast IP and provided better spatial resolution than the magnitude images. When IP was absent from the data, the EIT algorithm reconstructed phase values consistent with the data noise levels

  19. Broadband impedance of the NESTOR storage ring

    International Nuclear Information System (INIS)

    Androsov, V.P.; Gladkikh, P.I.; Gvozd, A.M.; Karnaukhov, I.M.; Telegin, Yu.N.

    2011-01-01

    The contributions from lossy and inductive vacuum chamber components to the broadband impedance of the NESTOR storage ring are obtained by using both low-frequency analytical approaches and computer simulations. As was expected considering the small ring circumference (15.44m), the main contributions both to the longitudinal impedance Z || /n and the loss factor k loss come from the RF-cavity. Cavity impedance was also estimated with CST Microwave Studio (CST Studio Suite TM 2006) by simulating coaxial wire method commonly used for impedance measurements. Both estimates agree well. Finally, we performed the simulations of a number of inductive elements with CST Particle Studio 2010 by using wake field solver. We have also evaluated the bunch length in NESTOR taking the conservative estimate of 3 Ohm for the ring broadband impedance and have found that the bunch length s z = 0.5 cm could be obtained in steady state operation mode for the designed bunch current of 10 mA and RF-voltage of 250 kV.

  20. Rf Discharge Impedance Measurements Using a New Method to Determine the Stray Impedances

    NARCIS (Netherlands)

    Bakker, L.P.; Kroesen, G.M.W.; Hoog, de F.J.

    1999-01-01

    The impedance of a capacitively coupled radio frequency discharge in a tubular fluorescent lamp filled with neon and mercury is measured. The stray impedances in the electrical network are determined using a new method that requires no extra instruments. The reflection of power is used to determine

  1. Elimination of the Respiratory Effect on the Thoracic Impedance Signal with Whole-body Impedance Cardiography

    Czech Academy of Sciences Publication Activity Database

    Jurák, Pavel; Halámek, Josef; Vondra, Vlastimil; Viščor, Ivo; Lipoldová, J.; Plachý, M.

    2010-01-01

    Roč. 37, - (2010), s. 1051-1054 ISSN 0276-6574 R&D Projects: GA AV ČR IAA200650801 Institutional research plan: CEZ:AV0Z20650511 Keywords : respiratory effect * thoracic impedance signal * impedance cardiography Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://cinc.mit.edu/archives/2010/pdf/1051.pdf

  2. Evaluation of electrical impedance ratio measurements in accuracy of electronic apex locators.

    Science.gov (United States)

    Kim, Pil-Jong; Kim, Hong-Gee; Cho, Byeong-Hoon

    2015-05-01

    The aim of this paper was evaluating the ratios of electrical impedance measurements reported in previous studies through a correlation analysis in order to explicit it as the contributing factor to the accuracy of electronic apex locator (EAL). The literature regarding electrical property measurements of EALs was screened using Medline and Embase. All data acquired were plotted to identify correlations between impedance and log-scaled frequency. The accuracy of the impedance ratio method used to detect the apical constriction (APC) in most EALs was evaluated using linear ramp function fitting. Changes of impedance ratios for various frequencies were evaluated for a variety of file positions. Among the ten papers selected in the search process, the first-order equations between log-scaled frequency and impedance were in the negative direction. When the model for the ratios was assumed to be a linear ramp function, the ratio values decreased if the file went deeper and the average ratio values of the left and right horizontal zones were significantly different in 8 out of 9 studies. The APC was located within the interval of linear relation between the left and right horizontal zones of the linear ramp model. Using the ratio method, the APC was located within a linear interval. Therefore, using the impedance ratio between electrical impedance measurements at different frequencies was a robust method for detection of the APC.

  3. Evaluation of electrical impedance ratio measurements in accuracy of electronic apex locators

    Directory of Open Access Journals (Sweden)

    Pil-Jong Kim

    2015-05-01

    Full Text Available Objectives The aim of this paper was evaluating the ratios of electrical impedance measurements reported in previous studies through a correlation analysis in order to explicit it as the contributing factor to the accuracy of electronic apex locator (EAL. Materials and Methods The literature regarding electrical property measurements of EALs was screened using Medline and Embase. All data acquired were plotted to identify correlations between impedance and log-scaled frequency. The accuracy of the impedance ratio method used to detect the apical constriction (APC in most EALs was evaluated using linear ramp function fitting. Changes of impedance ratios for various frequencies were evaluated for a variety of file positions. Results Among the ten papers selected in the search process, the first-order equations between log-scaled frequency and impedance were in the negative direction. When the model for the ratios was assumed to be a linear ramp function, the ratio values decreased if the file went deeper and the average ratio values of the left and right horizontal zones were significantly different in 8 out of 9 studies. The APC was located within the interval of linear relation between the left and right horizontal zones of the linear ramp model. Conclusions Using the ratio method, the APC was located within a linear interval. Therefore, using the impedance ratio between electrical impedance measurements at different frequencies was a robust method for detection of the APC.

  4. Evaluation of fluid status related parameters in hemodialysis and peritoneal dialysis patients: Clinical usefulness of bioimpedance analysis.

    Science.gov (United States)

    Yılmaz, Zülfükar; Yıldırım, Yaşar; Aydın, Fatma Yılmaz; Aydın, Emre; Kadiroğlu, Ali Kemal; Yılmaz, Mehmet Emin; Acet, Halit

    2014-01-01

    Fluid overload is a common and serious problem that leads to severe complications in dialysis patients. We aimed to compare hydration status as measured with bioimpedance analysis (BIA) method in hemodialysis (HD) and peritoneal dialysis (PD) patients, as well as investigating the association between blood pressure, left ventricular mass index (LVMI) and hydration status. We examined 43 HD and 33 PD patients. Blood pressure was recorded. In each group, echocardiographic examinations were performed on all patients. Hydration status was assessed using multifrequency bioelectrical impedance analysis. Overhydration was defined as an overhydration (OH)/extracellular water (ECW) ratio of >0.15. The OH/ECW ratio was significantly higher in PD patients compared to post-HD patients. Overhydration was statistically more frequent in PD than in post-HD patients (30.3% vs. 11.6%, P=0.043). Systolic blood pressure (SBP) in both post-HD and PD groups, and LVMI in the PD group were found to be significantly higher in overhydrated patients than non-overhydrated patients. In multiple linear regression analyses, increased OH/ECW ratio was independently associated with higher SBP and LVMI. Fluid overload may be an even more prevalent and serious problem in PD patients. Overhydration is closely associated with increased blood pressure and LVMI. OH/ECW ratio, a derived parameter of fluid load measured by BIA, was a significant and independent determinant of SBP and LVMI. Copyright © 2014 Lithuanian University of Health Sciences. Production and hosting by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  5. On the impedance of galvanic cells XVIII. The potential dependence of the faradaic impedance in the case of an irreversible electrode reaction, and its application to A.C. polarography

    NARCIS (Netherlands)

    Timmer, B.; Sluyters-Rehbach, M.; Sluyters, J.H.

    A theoretical treatment for the potential dependence of the faradaic impedance, in the case that the electrode reaction behaves irreversibly with respect to the direct current, using the steady-state concept, is presented. An analysis of the expressions obtained in the complex impedance plane is

  6. Impedance measurements of components for the ALS

    International Nuclear Information System (INIS)

    Corlett, J.N.; Rimmer, R.A.

    1993-05-01

    The high current and short bunch length of the ALS beam make the machine susceptible to beam instabilities over a frequency range extending to 13 GHz and beyond. All components of the storage ring have been carefully designed to minimize the impedance presented to the beam, and assemblies have been laid out to avoid resonant enclosures between components. Novel bellows shields allowing considerable mechanical movement while maintaining a low impedance are described. Results are presented of impedance measurements of ALS components and assemblies of components, using a precision coaxial wire technique in frequency domain, extending to frequencies beyond cut-off. All measurements were performed at the Lambertson Beam Electrodynamics Laboratory of the Center for Beam Physics at LBL

  7. Bunch length and impedance measurements in SPEAR

    International Nuclear Information System (INIS)

    Bane, K.; Donald, M.; Hofmann, A.; Jowett, J.; Lockman, W.; Morton, P.; Stege, R.; Spence, W.; Wilson, P.

    1988-05-01

    Subsequent to an extensive smoothing of the vacuum chamber a comprehensive study of the SPEAR impedance was undertaken. Bunch length, synchrotron quadrupole mode frequency, and parasitic mode loss were measured as functions of beam current. The results showed that, although the gross longitudinal impedance had indeed been reduced, the 'capacitive' component had also decreased relative to the 'inductive'--to the extent that previously compensated potential well distortion now induced bunch lengthening at low currents, and the turbulent threshold had actually been lowered. A specially designed multi-cell disc-loaded 'capacitor' cavity was shown to be capable of removing this effect by restoring the original compensation. A model of the new SPEAR impedance is also obtained. 7 refs., 6 figs

  8. Bunch length and impedance measurements in SPEAR

    International Nuclear Information System (INIS)

    Bane, K.; Donald, M.; Morton, P.; Stege, R.; Spence, W.; Wilson, P.; Hofmann, A.; Jowett, J.; Lockman, W.

    1988-01-01

    Subsequent to an extensive smoothing of the vacuum chamber a comprehensive study of the SPEAR impedance was undertaken. Bunch length, synchrotron quadrupole mode frequency, and parasitic mode loss were measured as functions of beam current. This paper shows that although the gross longitudinal impedance had indeed been reduced, the capacitive component had also decreased relative to the inductive - to the extent that previously compensated potential well distortion now induced bunch lengthening at low currents, and the turbulent threshold had actually been lowered. A specially designed multi-cell disc-loaded capacitor cavity was shown to be capable of removing this effect by restoring the original compensation. A model of the new SPEAR impedance is also obtained

  9. Coupling slots without shunt impedance drop

    International Nuclear Information System (INIS)

    Balleyguier, P.

    1996-01-01

    It is well known that coupling slots between adjacent cells in a π-mode structure reduce shunt impedance per unit length with respect to single cell cavities. To design optimized coupling slots, one has to answer the following question: for a given coupling factor, what shape, dimension, position and number of slots lead to the lowest shunt impedance drop? A numerical study using the 3D code MAFIA has been carried out. The aim was to design the 352 MHz cavities for the high intensity proton accelerator of the TRISPAL project. The result is an unexpected set of four 'petal' slots. Such slots should lead to a quasi-negligible drop in shunt impedance: about -1% on average, for particle velocity from 0.4 c to 0.8 c. (author)

  10. Impact of the Pb and Zn ore mining industry on the pollution of the Biała Przemsza River, Poland.

    Science.gov (United States)

    Jabłońska-Czapla, Magdalena; Nocoń, Katarzyna; Szopa, Sebastian; Łyko, Aleksandra

    2016-05-01

    The development of mining and metallurgic industries of Pb and Zn ores in the Biała Przemsza catchment area has had a strong influence on the condition of the surface water and bottom sediments. In the following study, total contents of metals and metalloids were researched in the water and bottom sediment samples from the Biała Przemsza River. The samples were collected monthly in 2014 at five sampling points along the river. The research helped to determine correlations between the parameters and components of the water environment (metals/metalloids, cations/anions, pH, Eh, conductivity, carbon (TOC, IC, TC), and suspension). The contents of metals and metalloids were determined with inductively coupled plasma-mass spectrometry (ICP-MS), whereas anions and cations were investigated with ion chromatography (IC). The simplified Community Bureau of Reference (BCR) three-step sequential chemical extraction was performed on Biała Przemsza River bottom sediments collected in April, July, and October. At its lower course, the Biała Przemsza River water did not meet the Polish surface water quality standards. The Biała Przemsza River water is mainly loaded with metals. Toxic concentrations of Cd, Pb, and Zn were observed at sampling points in Okradzionów and Sławków. The toxic Tl concentration was exceeded (2-6 μg/L) at three sampling points. The Biała Przemsza River bottom sediments were composed mostly of medium and fine sand. The BCR extraction of the bottom sediments demonstrated that Cd and Zn were bound to cations/anions and carbonates loosely adsorbed on the bottom sediments in spring and summer. Such a situation was observed at all the sampling points, except for BP3 in Okradzionów. The organic carbon concentration increased along the river course.

  11. Coupling IR Thermography and BIA to analyse body reaction after one acupuncture session

    International Nuclear Information System (INIS)

    Piquemal, M

    2013-01-01

    Coupling both thermography and bio-Impedance, some biophysical acupuncture mechanisms are statically studied on a small population of 18 subjects. Results show that a possible way of understanding acupuncture, in an electrical way, should be to consider ionic flux redistribution between vascular and extra cell compartments. This is a two steps mechanism. The first one is starting with needles insertion and the second one is lasting with more intensity after removing them from skin.

  12. Coupling IR Thermography and BIA to analyse body reaction after one acupuncture session

    Science.gov (United States)

    Piquemal, M.

    2013-04-01

    Coupling both thermography and bio-Impedance, some biophysical acupuncture mechanisms are statically studied on a small population of 18 subjects. Results show that a possible way of understanding acupuncture, in an electrical way, should be to consider ionic flux redistribution between vascular and extra cell compartments. This is a two steps mechanism. The first one is starting with needles insertion and the second one is lasting with more intensity after removing them from skin.

  13. Impedance Method for Leak Detection in Zigzag Pipelines

    Science.gov (United States)

    Lay-Ekuakille, A.; Vergallo, P.; Trotta, A.

    2010-01-01

    Transportation of liquids is a primary aspect of human life. The most important infrastructure used accordingly is the pipeline. It serves as an asset for transporting different liquids and strategic goods. The latter are for example: chemical substances, oil, gas and water. Thus, it is necessary to monitor such infrastructures by means of specific tools. Leakage detection methods are used to reveal liquid leaks in pipelines for many applications, namely, waterworks, oil pipelines, industry heat exchangers, etc. The configuration of pipelines is a key issue because it impacts on the effectiveness of the method to be used and, consequently, on the results to be counterchecked. This research illustrated an improvement of the impedance method for zigzag pipeline by carrying out an experimental frequency analysis that has been compared with other methods based on frequency response. Hence, the impedance method is generally used for simple (straight) pipeline configurations because complicated pipelines with many curves introduce difficulties and major uncertainties in the calculation of characteristic impedance and in the statement of boundary conditions. The paper illustrates the case of a water pipeline where the leakage is acquired thanks to pressure transducers.

  14. Pathogen identification using peptide nanotube biosensors and impedance AFM

    Science.gov (United States)

    Maccuspie, Robert I.

    Pathogen identification at highly sensitive levels is crucial to meet urgent needs in fighting the spread of disease or detecting bioterrorism events. Toward that end, a new method for biosensing utilizing fluorescent antibody nanotubes is proposed. Fundamental studies on the self-assembly of these peptide nanotubes are performed, as are applications of aligning these nanotubes on surfaces. As biosensors, these nanotubes incorporate recognition units with antibodies at their ends and fluorescent signaling units at their sidewalls. When viral pathogens were mixed with these antibody nanotubes in solution, the nanotubes rapidly aggregated around the viruses. The size of the aggregates increased as the concentration of viruses increased, as detected by flow cytometry on the order of attomolar concentrations by changes in fluorescence and light scattering intensities. This enabled determination of the concentrations of viruses at trace levels (102 to 106 pfu/mL) within 30 minutes from the receipt of samples to the final quantitative data analysis, as demonstrated on Adenovirus, Herpes Simplex Virus, Influenza, and Vaccinia virus. As another separate approach, impedance AFM is used to study the electrical properties of individual viruses and nanoparticles used as model systems. The design, development, and implementation of the impedance AFM for an Asylum Research platform is described, as well as its application towards studying the impedance of individual nanoparticles as a model system for understanding the fundamental science of how the life cycle of a virus affects its electrical properties. In combination, these approaches fill a pressing need to quantify viruses both rapidly and sensitively.

  15. Dielectric and impedance spectroscopic studies of neodymium gallate

    Energy Technology Data Exchange (ETDEWEB)

    Sakhya, Anup Pradhan, E-mail: npshakya31@gmail.com [Department of Physics, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009 (India); Dutta, Alo [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Sinha, T.P. [Department of Physics, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009 (India)

    2016-05-01

    The AC electrical properties of a polycrystalline neodymium gallate, NdGaO{sub 3} (NGO), synthesized by the sol–gel method have been investigated by employing impedance spectroscopy in the frequency range from 42 Hz to 5 MHz and in the temperature range from 323 K to 593 K. The X-ray diffraction analysis shows that the compound crystallizes in the orthorhombic phase with Pbnm space group at room temperature. Two relaxation processes with different relaxation times are observed from the impedance as well as modulus spectroscopic measurements, which have been attributed to the grain and the grain boundary effects at different temperatures in NGO. The complex impedance data are analyzed by an electrical equivalent circuit consisting of a resistance and a constant phase element in parallel. It has been observed that the value of the capacitance and the resistance associated with the grain boundary is higher than those associated with the grain. The temperature dependent electrical conductivity shows the negative temperature coefficient of resistance. The frequency dependent conductivity spectra are found to follow the power law.

  16. Dynamic impedance compensation for wireless power transfer using conjugate power

    Science.gov (United States)

    Liu, Suqi; Tan, Jianping; Wen, Xue

    2018-02-01

    Wireless power transfer (WPT) via coupled magnetic resonances has been in development for over a decade. However, the frequency splitting phenomenon occurs in the over-coupled region. Thus, the output power of the two-coil system achieves the maximum output power at the two splitting angular frequencies, and not at the natural resonant angular frequency. According to the maximum power transfer theorem, the impedance compensation method was adopted in many WPT projects. However, it remains a challenge to achieve the maximum output power and transmission efficiency in a fixed-frequency mode. In this study, dynamic impedance compensation for WPT was presented by utilizing the compensator within a virtual three-coil WPT system. First, the circuit model was established and transfer characteristics of a system were studied by utilizing circuit theories. Second, the power superposition of the WPT system was carefully researched. When a pair of compensating coils was inserted into the transmitter loop, the conjugate power of the compensator loop was created via magnetic coupling of the two compensating coils that insert into the transmitter loop. The mechanism for dynamic impedance compensation for wireless power transfer was then provided by investigating a virtual three-coil WPT system. Finally, the experimental circuit of a virtual three-coil WPT system was designed, and experimental results are consistent with the theoretical analysis, which achieves the maximum output power and transmission efficiency.

  17. Dynamic impedance compensation for wireless power transfer using conjugate power

    Directory of Open Access Journals (Sweden)

    Suqi Liu

    2018-02-01

    Full Text Available Wireless power transfer (WPT via coupled magnetic resonances has been in development for over a decade. However, the frequency splitting phenomenon occurs in the over-coupled region. Thus, the output power of the two-coil system achieves the maximum output power at the two splitting angular frequencies, and not at the natural resonant angular frequency. According to the maximum power transfer theorem, the impedance compensation method was adopted in many WPT projects. However, it remains a challenge to achieve the maximum output power and transmission efficiency in a fixed-frequency mode. In this study, dynamic impedance compensation for WPT was presented by utilizing the compensator within a virtual three-coil WPT system. First, the circuit model was established and transfer characteristics of a system were studied by utilizing circuit theories. Second, the power superposition of the WPT system was carefully researched. When a pair of compensating coils was inserted into the transmitter loop, the conjugate power of the compensator loop was created via magnetic coupling of the two compensating coils that insert into the transmitter loop. The mechanism for dynamic impedance compensation for wireless power transfer was then provided by investigating a virtual three-coil WPT system. Finally, the experimental circuit of a virtual three-coil WPT system was designed, and experimental results are consistent with the theoretical analysis, which achieves the maximum output power and transmission efficiency.

  18. The IMPACT shirt: textile integrated and portable impedance cardiography

    International Nuclear Information System (INIS)

    Ulbrich, Mark; Wan, Tingting; Leonhardt, Steffen; Walter, Marian; Mühlsteff, Jens; Sipilä, Auli; Kamppi, Merja; Koskela, Anne; Myry, Manu

    2014-01-01

    Measurement of hemodynamic parameters such as stroke volume (SV) via impedance cardiography (ICG) is an easy, non-invasive and inexpensive way to assess the health status of the heart. We present a possibility to use this technology for monitoring risk patients at home. The IMPACT Shirt (IMPedAnce Cardiography Textile) has been developed with integrated textile electrodes and textile wiring, as well as with portable miniaturized hardware. Several textile materials were characterized in vitro and in vivo to analyze their performance with regard to washability, and electrical characteristics such as skin-electrode impedance, capacitive coupling and subjective tactile feeling. The small lightweight hardware measures ECG and ICG continuously and transmits wireless data via Bluetooth to a mobile phone (Android) or PC for further analysis. A lithium polymer battery supplies the circuit and can be charged via a micro-USB. Results of a proof-of-concept trial show excellent agreement between SV assessed by a commercial device and the developed system. The IMPACT Shirt allows monitoring of SV and ECG on a daily basis at the patient’s home. (paper)

  19. Electrochemical Impedance Spectroscopy Of Metal Alloys

    Science.gov (United States)

    Macdowell, L. G.; Calle, L. M.

    1993-01-01

    Report describes use of electrochemical impedance spectroscopy (EIS) to investigate resistances of 19 alloys to corrosion under conditions similar to those of corrosive, chloride-laden seaside environment of Space Transportation System launch site. Alloys investigated: Hastelloy C-4, C-22, C-276, and B-2; Inconel(R) 600, 625, and 825; Inco(R) G-3; Monel 400; Zirconium 702; Stainless Steel 304L, 304LN, 316L, 317L, and 904L; 20Cb-3; 7Mo+N; ES2205; and Ferralium 255. Results suggest electrochemical impedance spectroscopy used to predict corrosion performances of metal alloys.

  20. Real-Time Thevenin Impedance Computation

    DEFF Research Database (Denmark)

    Sommer, Stefan Horst; Jóhannsson, Hjörtur

    2013-01-01

    operating state, and strict time constraints are difficult to adhere to as the complexity of the grid increases. Several suggested approaches for real-time stability assessment require Thevenin impedances to be determined for the observed system conditions. By combining matrix factorization, graph reduction......, and parallelization, we develop an algorithm for computing Thevenin impedances an order of magnitude faster than previous approaches. We test the factor-and-solve algorithm with data from several power grids of varying complexity, and we show how the algorithm allows realtime stability assessment of complex power...