AIM To evaluate the prognostic value of the phase angle(PA)obtained from bioelectrical impedance analysis(BIA)for mortality prediction in patients with cirrhosis.METHODS In total,134 male cirrhotic patients prospectiv...AIM To evaluate the prognostic value of the phase angle(PA)obtained from bioelectrical impedance analysis(BIA)for mortality prediction in patients with cirrhosis.METHODS In total,134 male cirrhotic patients prospectively completed clinical evaluations and nutritional assessment by BIA to obtain PAs during a 36-mo follow-up period.Mortality risk was analyzed by applying the PA cutoff point recently proposed as a malnutrition marker(PA≤4.9°)in Kaplan-Meier curves and multivariate Cox regression models.RESULTS The patients were divided into two groups according to the PA cutoff value(PA>4.9°,n=73;PA≤4.9°,n=61).Weight,height,and body mass index were similar in both groups,but patients with PAs>4.9°were younger and had higher mid-arm muscle circumference,albumin,and handgrip-strength values and lower severe ascites and encephalopathy incidences,interleukin(IL)-6/IL-10 ratios and C-reactive protein levels than did patients with PAs≤4.9°(P≤0.05).Forty-eight(35.80%)patients died due to cirrhosis,with a median of 18 mo(interquartile range,3.3-25.6 mo)follow-up until death.Thirty-one(64.60%)of these patients were from the PA≤4.9°group.PA≤4.9°significantly and independently affected the mortality model adjusted for Model for End-Stage Liver Disease score and age(hazard ratio=2.05,95%CI:1.11-3.77,P=0.021).In addition,Kaplan-Meier curves showed that patients with PAs≤4.9°were significantly more likely to die.CONCLUSION In male patients with cirrhosis,the PA≤4.9°cutoff was associated independently with mortality and identified patients with worse metabolic,nutritional,and disease progression profiles.The PA may be a useful and reliable bedside tool to evaluate prognosis in cirrhosis.展开更多
Electrical impedance （El） and phase angle （PHI） parameters in AC impedance spectroscopy are important electrical parameters in the study of medical pathology. However, little is known about their application in va...Electrical impedance （El） and phase angle （PHI） parameters in AC impedance spectroscopy are important electrical parameters in the study of medical pathology. However, little is known about their application in variation and genetic relationship studies of forest trees. In order to test whether impedance parameters could be used in genetic relationship analysis among conifer species, E1 and PHI were measured in a seedling experiment test composed of Pinus tabuliformis, Pinus yunnanensis, and Pinus densata in a habitat of Pinus tabuliformis. The results showed that variations in both EI and PHI among species were sig- nificant in different electric frequencies, and the EI and PHI values measured in the two populations of P. densata were between the two parental species, P. yunnanensis and P. tabuliformis. These results show that these two impedance parameters could reflect the genetic relationship among pine species. This was the first time using the two AC impedance spectroscopy parameters to test the genetic relationship analysis between tree species, and would be a hopeful novelreference methodology for future studies in evolution and genetic variation of tree species.展开更多
Objective Bioelectrical impedance analysis(BIA)is used to measure a patient's body composition.The phase angle(PA),the major parameter in BIA,is one of the most sensitive indicators of malnutrition.The aim of the ...Objective Bioelectrical impedance analysis(BIA)is used to measure a patient's body composition.The phase angle(PA),the major parameter in BIA,is one of the most sensitive indicators of malnutrition.The aim of the current study was to investigate whether the PA can be used to predict survival in lung cancer patients.Methods One hundred sixty-six lung cancer patients were prospectively included from January 2014 to August 2016 in Daping Hospital.Anthropometric measurements,hematological values,the nutritional risk screening(NRS 2002)score,patient generated-subjective global assessment(PG-SGA)score,Karnofsky performance status(KPS)scale,European Organization for Research and Treatment of Cancer Core Quality of Life Questionnaire(EORTC QLQ C-30)score,and BIA were investigated within 48 hours after admission to the hospital.A Spearman correlation analysis was applied to test the correlations between the study characteristics and PA.A Kaplan-Meier analysis and log-rank test were conducted to analyze the association between the overall survival(OS)and PA.Results The mean age for all patients was 63 years old(42 females and 124 males).The median PA was 5.5°(4.70°,6.23°).The PA was positively associated with the body mass index,hand grip strength,mid-arm circumference,mid-arm muscle circumference,albumin,prealbumin,C-reactive protein,red blood cells,hemoglobin and KPS score.The PG-SGA scores,QLQ-C30 score,and NRS2002 score showed a significant negative association with the PA.According to a multivariate analysis,the PA(HR=0.47;95%CI:0.27-0.81)was independent predictor of the lung cancer patients'long-term OS.Patients with a higher PA(≥5°)had better overall survival(median=426 days)compared to those with a lower PA(<5°)(median=96 days)based on the one-year follow-up data(P<0.0001).Conclusions These studies indicate that the PA is a sensitive and early indicator to predict survival in lung cancer patients.展开更多
It is estimated in Western industrialized countries that inflammatory bowel disease(IBD)has a prevalence of 1 for every 200 inhabitants.In the past,the fat mass disproportionate increase in relation to the fat-free ma...It is estimated in Western industrialized countries that inflammatory bowel disease(IBD)has a prevalence of 1 for every 200 inhabitants.In the past,the fat mass disproportionate increase in relation to the fat-free mass was considered uncommon in patients with IBD,due to the observation of the disease being more common with weight loss and malnutrition.However,more in-depth investigations demonstrate that the fat/lean mass disproportion stands out both in prevalence in patients with new diagnoses of ulcerative colitis or Crohn's disease as well as a factor of poor prognosis to the natural evolution of the disease or to the therapeutic response.Another important aspect associated with obesity in IBD is the increased risk of drug clearance[including anti-tumor necrosis factor(TNF)and anti-integrin agents],resulting in short half-life and low trough drug concentrations,since the levels of TNF secreted by adipocytes sequester anti-TNF agents,which could result in suboptimal response to biologics.In view of these characteristic aspects of the inflammatory process of IBD,the identification of cellular functioning is necessary,which can be associated with the staging of the underlying disease,biochemical parameters,and body composition,helping as an indicator for a more accurate clinical and nutritional conduct.展开更多
Protein-calorie malnutrition (PCM) is a common condition in cirrhotic patients, leading to a worse prognosis, complications, poor quality of life and lower survival rates. Among ways of assessing nutritional status, t...Protein-calorie malnutrition (PCM) is a common condition in cirrhotic patients, leading to a worse prognosis, complications, poor quality of life and lower survival rates. Among ways of assessing nutritional status, there are anthropometric methods such as the evaluation of the triceps skinfold, the arm circumference, the arm muscle circumference and the body mass index, and non-anthropometric methods such as the subjective global assessment, the handgrip strength of non-dominant hand, and the bioelectrical impedance analysis (BIA). PCM is frequently under-diagnosed in clinical settings in patients with cirrhosis due to the limitations of nutritional evaluation methods in this population. BIA is a useful method, but cannot be indicated in patients with abnormal body composition. In these situations, the phase angle (PA) has been used, and can become an important tool in assessing nutritional status in any situation. The PA is superior to anthropometric methods and might be considered as a nutritional indicator in cirrhosis. The early characterization of the nutritional status in patients with cirrhosis means an early nutritional intervention, with a positive impact on patients’ overall prognosis. Among the usually accepted methods for nutritional diagnosis, the PA provides information in a quick and objective manner.展开更多
Background The phase angle(PA)is an indicator of nutritional status derived from bioelectrical impedance analysis(BIA).Studies have shown that the PA is one of several factors related to the survival of cancer patient...Background The phase angle(PA)is an indicator of nutritional status derived from bioelectrical impedance analysis(BIA).Studies have shown that the PA is one of several factors related to the survival of cancer patients.However,the correlation between the PA and prognosis in patients with hepatocellular carcinoma(HCC)has not been reported.This study aimed to explore the relationship between the PA,nutrition-related indicators,and patient prognosis.Methods The data from 248 HCC patients who underwent BIA between January 2015 and December 2019 at the First Hospital of Jilin University were retrospectively analyzed.Patients were divided into two groups according to the median PA value,then the nutrition-related indicators and overall survival(OS)were compared between the two groups.The correlations between the PA and laboratory test nutrition-related indicators and the results of a body composition analysis were determined using Pearson correlation analysis.Independent predictors of the patient prognosis were identified using univariate and multivariate analyses.Results The median OS in the high and low PA groups were 70 and 54.6 months,respectively(P=0.004).The Pearson correlation analysis revealed that the PA was associated with both laboratory test nutrition-related indicators and the results of a body composition analysis.The multivariable Cox regression analysis identified the PA as an independent risk factor affecting the prognosis of patients with Barcelona Clinic Liver Cancer stage A or B.Conclusion The PA is a good biomarker for the nutritional status.We found that the PA was associated with the prognosis in patients with HCC,with a low PA indicating a poor nutritional status and worse prognosis.展开更多
Soil is a typical porous media and its impedance characteristic directly determines the performance of grounding system. Soil phase frequency characteristic measurements were carried out on various soil types and wate...Soil is a typical porous media and its impedance characteristic directly determines the performance of grounding system. Soil phase frequency characteristic measurements were carried out on various soil types and water content. This paper finds that the impedance angle of soil specimen presents a capacitive performance when power frequency (f) is low. As the frequency increases, soil impedance angle goes up rapidly. Furthermore the frequency characteristic while f > 1000 Hz is distinct in terms of different water content. In particular, at low moisture content, soil impedance angle would be higher than 0?, that is, the inductive component is obvious. The study result indicates that porous media possesses the unique conductivity property dif-ferent from conductor and solution. Its mechanism needs further study.展开更多
BACKGROUND Malnutrition,lipodystrophy,and dyslipidemia are prevalent characteristics in patients with human immunodeficiency virus(HIV)infection with or without previous treatment.Such a clinical condition can lead to...BACKGROUND Malnutrition,lipodystrophy,and dyslipidemia are prevalent characteristics in patients with human immunodeficiency virus(HIV)infection with or without previous treatment.Such a clinical condition can lead to the hypothesis of the presence of hepatic steatosis with possible progression to fibrosis and the risk of hepatocellular carcinoma.Notably,a low phase angle(PA),evaluated by bioelectrical impedance analysis(BIA),is an independent prognostic marker of clinical progression and survival in HIV-infected patients.AIM To evaluate the relationship between PA and body composition with steatosis and hepatic fibrosis in HIV/hepatitis C virus(HCV)-coinfected patients.METHODS A retrospective observational study by convenience sampling of coinfected HIV/HCV patients,in which all patients underwent transient elastography(Fibroscan)and BIA evaluation.Student’s t test was used for group comparisons,and Spearman’s or Pearson’s correlation test was used when appropriate.The significance level was set at 5%,and analyses were performed using SPSS version 21.0.RESULTS Forty-three patients who received antiretroviral therapy met the inclusion criteria,and 23(53.5%)were under treatment with protease inhibitors(PIs).There was no difference in PA between those who used PIs and those who did not(P=0.635).There was no correlation between fibrosis grade and PA(P=0.355)or lean mass(P=0.378).There was a significant inverse correlation between the controlled attenuation parameter(CAP)and lean mass(P=0.378),positive correlation between PA and lean mass(P=0.378),and negative correlation between PA and fatty mass(P=0.378),although the CAP and PA were not correlated.When evaluated by sex,no significant correlations were found.CONCLUSION PA determines the muscle function of HIV/HCV-coinfected patients,and the CAP values reinforce the association with lean mass,suggesting that patients require early nutritional interventions.展开更多
Bioelectrical impedance analysis(BIA)is a noninvasive and reproducible technique for assessing changes in body composition and nutritional status.The phase angle(PA),a major parameter of BIA,is one of the most sensiti...Bioelectrical impedance analysis(BIA)is a noninvasive and reproducible technique for assessing changes in body composition and nutritional status.The phase angle(PA),a major parameter of BIA,is one of the most sensitive indicators used to detect malnutrition in patients,and is also a prognostic marker in various clinical diseases.The incidence of malnutrition in cancer patients is high,and malnutrition seriously affects the treatment process and prognosis of patients.Reasonable and effective nutritional interventions are therefore of great significance for cancer patients.Compared with traditional nutritional assessment tools,the PA has unique advantages in the nutritional assessment,efficacy monitoring and prognostic prediction of patients with malignant tumors,and it has broad application prospects in clinical practice.This article reviews the research progress on the application of the PA in patients with malignant tumors to provide clinicians with a tool to predict malnutrition,and provide a more favorable basis for the nutritional assessment,treatment and prognostic prediction of cancer patients.展开更多
Out-of-step oscillation separation devices based on apparent impedance angle trajectory are widely used in the power grid in China,and their reliability is of great importance.In this paper,the influence mechanism of ...Out-of-step oscillation separation devices based on apparent impedance angle trajectory are widely used in the power grid in China,and their reliability is of great importance.In this paper,the influence mechanism of series compensation on apparent impedance angle trajectory is analyzed.It reveals that series compensation capacitors reduce the equivalent impedance angle and consequently the apparent impedance angle cannot pass through all four zones,resulting in the risk of failure for the separation devices.A revised method of apparent impedance angle based on compensation principle is discussed,and then an improved out-of-step oscillation detection criterion is proposed.In view of the fact that the apparent impedance angle at the moment of maximum current is equal to the equivalent impedance angle during an oscillation process,a practical algorithm based on the compensated apparent impedance angle is proposed.RTDS tests are conducted to verify the effectiveness of the new criterion,considering transmission lines with a high series compensation level.展开更多
Current and voltage waveforms recorded by intelligent electronic devices(IEDs)are more useful than just performing post-fault analysis.The objective of this paper is to present techniques to estimate the zero-sequence...Current and voltage waveforms recorded by intelligent electronic devices(IEDs)are more useful than just performing post-fault analysis.The objective of this paper is to present techniques to estimate the zero-sequence line impedance of all sections of a three-terminal line and the Thevenin equivalent impedance of the transmission network upstream from the monitoring location using protective relay data collected during short-circuit ground fault events.Protective relaying data from all three terminals may not be always available.Furthermore,the data from each terminal may be unsynchronized and collected at different sampling rates with dissimilar fault time instants.Hence,this paper presents approaches which use unsynchronized measurement data from all the terminals as well as data from only two terminals to estimate the zero-sequence line impedance of all the sections of a three-terminal line.An algorithm to calculate positive-,negative-and zero-sequence Thevenin impedance of the upstream transmission network has also been presented in this paper.The efficacy of the proposed algorithms are demonstrated using a test case.The magnitude error percentage in determining the zero-sequence impedance was less than 1%in the test case presented.展开更多
With the increased penetration of non-conventionalrenewable energy resources, such as wind power plants (WPPs),into the power system, a lot of interest has been placed on studyingtheir impact for system protection, pl...With the increased penetration of non-conventionalrenewable energy resources, such as wind power plants (WPPs),into the power system, a lot of interest has been placed on studyingtheir impact for system protection, planning and operationsto ensure continued reliability of the electric grid. The impactof WPPs on the grid is typically identified during generationinterconnection studies. One of the challenges faced by protectionand planning engineers, at an early stage in this process, isthat many of the studies involving these power plants must beperformed without specific data available because the equipmentis not built yet. Among all the needed data, a particular interest inthis study is placed on the positive- and zero-sequence impedancesof the main power transformer (MPT) that interconnects a windpower plant to the transmission system due to its contribution toshort-circuit current during ground faults. The most commonlyfound in practice MPT winding configurations is a high-voltagewinding in wye with neutral bushing;a low-voltage windingin wye with neutral bushing without phase shift between thesewindings, and a stabilizing tertiary winding connected in deltathat is not designed for external loading designated as YNyn0+d.Thus, this paper proposes a methodology to estimate the sequenceimpedances of YNyn0+d transformers from a statistical point ofview applying clustering and regression analyses on existing MPTtest report data.展开更多
Objective: To investigate the diagnostic value of phase angle based on bioelectrical impedance method in senile sarcopenia. Methods: Clinical data from patients aged 60 and above who received treatment in our hospital...Objective: To investigate the diagnostic value of phase angle based on bioelectrical impedance method in senile sarcopenia. Methods: Clinical data from patients aged 60 and above who received treatment in our hospital from January 2023 to January 2023 were retrospectively collected and analyzed. A total of 214 cases were divided into two groups based on the presence or absence of sarcopenia. The baseline data of the two groups were compared, and multiple regression analysis was conducted to identify the independent risk factors of sarcopenia in the elderly. Additionally, the diagnostic effect of phase angle on sarcopenia in the elderly was assessed using the ROC curve analysis. Results: A total of 214 cases were included, of which 103patients(48.131%) were diagnosed with sarcopenia, while the remaining 111 patients(51.869%) with non-sarcopenia. The results showed that the age of sarcopenia group was significantly higher than that of non-sarcopenia group(P<0.05). Additionally, total body moisture, protein, inorganic salts, body fat, phase angle, skeletal muscle mass index, grip strength and 6-m pace were significantly lower in sarcopenia group than those in non-sarcopenia group(P<0.05). Correlation and regression analyses identified phase angle, BMI, total body moisture, and body fat as independent risk factors for sarcopenia in the elderly(OR >1). ROC curve analysis showed that the areas under AUC for the phase angle, BMI, total body moisture, and body fat AUC were 0.762,0.650, 0.685, and 0.660, respectively. The highest combined diagnostic AUC was 0.865,indicating that the combined diagnosis had a better diagnostic effect on sarcopenia in the elderly. Conclusion: Phase angle serves as an effective index for detecting sarcopenia in the elderly, which can effectively evaluate muscle mass and muscle strength. It suggests that phase angle as an easy-to-monitor indicator is conductive to a more accurate and convenient diagnosis of sarcopenia.展开更多
针对顺北超深层碳酸盐岩断控缝洞型储集体储层非均质性强、地震资料信噪比低、叠后储层预测精度不足及裂缝识别困难等问题,基于五维地震数据,探索了提高裂缝型储层预测精度的新方法。在研究顺北断控缝洞型油气藏储层发育特征的基础上,...针对顺北超深层碳酸盐岩断控缝洞型储集体储层非均质性强、地震资料信噪比低、叠后储层预测精度不足及裂缝识别困难等问题,基于五维地震数据,探索了提高裂缝型储层预测精度的新方法。在研究顺北断控缝洞型油气藏储层发育特征的基础上,开展了五维地震各向异性正演模拟,建立了地震振幅与裂缝参数的关系,并优选了裂缝预测敏感参数;在此基础上推导出傅里叶级数形式的方位弹性阻抗方程,开展了裂缝型储层预测,并在顺北X井区进行了应用。研究结果明确了超深层碳酸盐岩断控储集体的AVAZ(amplitude variation with azimuth and offset)地震响应特征,指出裂缝密度是指示裂缝型储层的敏感参数;同时,利用二阶傅里叶系数表征了裂缝发育密度,在顺北X井区实现了裂缝型储层的精细表征,预测吻合率较高。基于振幅属性的五维地震预测技术通过挖掘宽方位地震数据的振幅、方位信息,丰富了裂缝发育密度和方向等相关信息的预测。建立的傅里叶系数-裂缝密度映射关系为断控缝洞型油藏预测提供了定量化工具,为断控缝洞型油藏裂缝预测及目标评价提供了新的思路。展开更多
基金Supported by The Fundacao de Amparo a Pesquisa do Estado de Sao Paulo,Nos.2011/13243-3,2012/15677-3[GB]
文摘AIM To evaluate the prognostic value of the phase angle(PA)obtained from bioelectrical impedance analysis(BIA)for mortality prediction in patients with cirrhosis.METHODS In total,134 male cirrhotic patients prospectively completed clinical evaluations and nutritional assessment by BIA to obtain PAs during a 36-mo follow-up period.Mortality risk was analyzed by applying the PA cutoff point recently proposed as a malnutrition marker(PA≤4.9°)in Kaplan-Meier curves and multivariate Cox regression models.RESULTS The patients were divided into two groups according to the PA cutoff value(PA>4.9°,n=73;PA≤4.9°,n=61).Weight,height,and body mass index were similar in both groups,but patients with PAs>4.9°were younger and had higher mid-arm muscle circumference,albumin,and handgrip-strength values and lower severe ascites and encephalopathy incidences,interleukin(IL)-6/IL-10 ratios and C-reactive protein levels than did patients with PAs≤4.9°(P≤0.05).Forty-eight(35.80%)patients died due to cirrhosis,with a median of 18 mo(interquartile range,3.3-25.6 mo)follow-up until death.Thirty-one(64.60%)of these patients were from the PA≤4.9°group.PA≤4.9°significantly and independently affected the mortality model adjusted for Model for End-Stage Liver Disease score and age(hazard ratio=2.05,95%CI:1.11-3.77,P=0.021).In addition,Kaplan-Meier curves showed that patients with PAs≤4.9°were significantly more likely to die.CONCLUSION In male patients with cirrhosis,the PA≤4.9°cutoff was associated independently with mortality and identified patients with worse metabolic,nutritional,and disease progression profiles.The PA may be a useful and reliable bedside tool to evaluate prognosis in cirrhosis.
基金funded by the Natural Science Foundation of China(31070591)Special National Forestry Public Welfare Industry Research(201104022)the support of Agriculture and Animal Husbandry College of Tibet University
文摘Electrical impedance （El） and phase angle （PHI） parameters in AC impedance spectroscopy are important electrical parameters in the study of medical pathology. However, little is known about their application in variation and genetic relationship studies of forest trees. In order to test whether impedance parameters could be used in genetic relationship analysis among conifer species, E1 and PHI were measured in a seedling experiment test composed of Pinus tabuliformis, Pinus yunnanensis, and Pinus densata in a habitat of Pinus tabuliformis. The results showed that variations in both EI and PHI among species were sig- nificant in different electric frequencies, and the EI and PHI values measured in the two populations of P. densata were between the two parental species, P. yunnanensis and P. tabuliformis. These results show that these two impedance parameters could reflect the genetic relationship among pine species. This was the first time using the two AC impedance spectroscopy parameters to test the genetic relationship analysis between tree species, and would be a hopeful novelreference methodology for future studies in evolution and genetic variation of tree species.
基金supported by the National Natural Science Foundation of China(No:81673167 to Hongxia Xu)the Chongqing Technology Innovation and Application Dem on stration Project for Social Livelihood(cstc2018jscx-msybX0094,to Jie Liu).
文摘Objective Bioelectrical impedance analysis(BIA)is used to measure a patient's body composition.The phase angle(PA),the major parameter in BIA,is one of the most sensitive indicators of malnutrition.The aim of the current study was to investigate whether the PA can be used to predict survival in lung cancer patients.Methods One hundred sixty-six lung cancer patients were prospectively included from January 2014 to August 2016 in Daping Hospital.Anthropometric measurements,hematological values,the nutritional risk screening(NRS 2002)score,patient generated-subjective global assessment(PG-SGA)score,Karnofsky performance status(KPS)scale,European Organization for Research and Treatment of Cancer Core Quality of Life Questionnaire(EORTC QLQ C-30)score,and BIA were investigated within 48 hours after admission to the hospital.A Spearman correlation analysis was applied to test the correlations between the study characteristics and PA.A Kaplan-Meier analysis and log-rank test were conducted to analyze the association between the overall survival(OS)and PA.Results The mean age for all patients was 63 years old(42 females and 124 males).The median PA was 5.5°(4.70°,6.23°).The PA was positively associated with the body mass index,hand grip strength,mid-arm circumference,mid-arm muscle circumference,albumin,prealbumin,C-reactive protein,red blood cells,hemoglobin and KPS score.The PG-SGA scores,QLQ-C30 score,and NRS2002 score showed a significant negative association with the PA.According to a multivariate analysis,the PA(HR=0.47;95%CI:0.27-0.81)was independent predictor of the lung cancer patients'long-term OS.Patients with a higher PA(≥5°)had better overall survival(median=426 days)compared to those with a lower PA(<5°)(median=96 days)based on the one-year follow-up data(P<0.0001).Conclusions These studies indicate that the PA is a sensitive and early indicator to predict survival in lung cancer patients.
文摘It is estimated in Western industrialized countries that inflammatory bowel disease(IBD)has a prevalence of 1 for every 200 inhabitants.In the past,the fat mass disproportionate increase in relation to the fat-free mass was considered uncommon in patients with IBD,due to the observation of the disease being more common with weight loss and malnutrition.However,more in-depth investigations demonstrate that the fat/lean mass disproportion stands out both in prevalence in patients with new diagnoses of ulcerative colitis or Crohn's disease as well as a factor of poor prognosis to the natural evolution of the disease or to the therapeutic response.Another important aspect associated with obesity in IBD is the increased risk of drug clearance[including anti-tumor necrosis factor(TNF)and anti-integrin agents],resulting in short half-life and low trough drug concentrations,since the levels of TNF secreted by adipocytes sequester anti-TNF agents,which could result in suboptimal response to biologics.In view of these characteristic aspects of the inflammatory process of IBD,the identification of cellular functioning is necessary,which can be associated with the staging of the underlying disease,biochemical parameters,and body composition,helping as an indicator for a more accurate clinical and nutritional conduct.
文摘Protein-calorie malnutrition (PCM) is a common condition in cirrhotic patients, leading to a worse prognosis, complications, poor quality of life and lower survival rates. Among ways of assessing nutritional status, there are anthropometric methods such as the evaluation of the triceps skinfold, the arm circumference, the arm muscle circumference and the body mass index, and non-anthropometric methods such as the subjective global assessment, the handgrip strength of non-dominant hand, and the bioelectrical impedance analysis (BIA). PCM is frequently under-diagnosed in clinical settings in patients with cirrhosis due to the limitations of nutritional evaluation methods in this population. BIA is a useful method, but cannot be indicated in patients with abnormal body composition. In these situations, the phase angle (PA) has been used, and can become an important tool in assessing nutritional status in any situation. The PA is superior to anthropometric methods and might be considered as a nutritional indicator in cirrhosis. The early characterization of the nutritional status in patients with cirrhosis means an early nutritional intervention, with a positive impact on patients’ overall prognosis. Among the usually accepted methods for nutritional diagnosis, the PA provides information in a quick and objective manner.
基金Science and Technology Department of Jilin Provincial(No.3D5204167428 for Dr.Nan Ya Wang).
文摘Background The phase angle(PA)is an indicator of nutritional status derived from bioelectrical impedance analysis(BIA).Studies have shown that the PA is one of several factors related to the survival of cancer patients.However,the correlation between the PA and prognosis in patients with hepatocellular carcinoma(HCC)has not been reported.This study aimed to explore the relationship between the PA,nutrition-related indicators,and patient prognosis.Methods The data from 248 HCC patients who underwent BIA between January 2015 and December 2019 at the First Hospital of Jilin University were retrospectively analyzed.Patients were divided into two groups according to the median PA value,then the nutrition-related indicators and overall survival(OS)were compared between the two groups.The correlations between the PA and laboratory test nutrition-related indicators and the results of a body composition analysis were determined using Pearson correlation analysis.Independent predictors of the patient prognosis were identified using univariate and multivariate analyses.Results The median OS in the high and low PA groups were 70 and 54.6 months,respectively(P=0.004).The Pearson correlation analysis revealed that the PA was associated with both laboratory test nutrition-related indicators and the results of a body composition analysis.The multivariable Cox regression analysis identified the PA as an independent risk factor affecting the prognosis of patients with Barcelona Clinic Liver Cancer stage A or B.Conclusion The PA is a good biomarker for the nutritional status.We found that the PA was associated with the prognosis in patients with HCC,with a low PA indicating a poor nutritional status and worse prognosis.
文摘Soil is a typical porous media and its impedance characteristic directly determines the performance of grounding system. Soil phase frequency characteristic measurements were carried out on various soil types and water content. This paper finds that the impedance angle of soil specimen presents a capacitive performance when power frequency (f) is low. As the frequency increases, soil impedance angle goes up rapidly. Furthermore the frequency characteristic while f > 1000 Hz is distinct in terms of different water content. In particular, at low moisture content, soil impedance angle would be higher than 0?, that is, the inductive component is obvious. The study result indicates that porous media possesses the unique conductivity property dif-ferent from conductor and solution. Its mechanism needs further study.
文摘BACKGROUND Malnutrition,lipodystrophy,and dyslipidemia are prevalent characteristics in patients with human immunodeficiency virus(HIV)infection with or without previous treatment.Such a clinical condition can lead to the hypothesis of the presence of hepatic steatosis with possible progression to fibrosis and the risk of hepatocellular carcinoma.Notably,a low phase angle(PA),evaluated by bioelectrical impedance analysis(BIA),is an independent prognostic marker of clinical progression and survival in HIV-infected patients.AIM To evaluate the relationship between PA and body composition with steatosis and hepatic fibrosis in HIV/hepatitis C virus(HCV)-coinfected patients.METHODS A retrospective observational study by convenience sampling of coinfected HIV/HCV patients,in which all patients underwent transient elastography(Fibroscan)and BIA evaluation.Student’s t test was used for group comparisons,and Spearman’s or Pearson’s correlation test was used when appropriate.The significance level was set at 5%,and analyses were performed using SPSS version 21.0.RESULTS Forty-three patients who received antiretroviral therapy met the inclusion criteria,and 23(53.5%)were under treatment with protease inhibitors(PIs).There was no difference in PA between those who used PIs and those who did not(P=0.635).There was no correlation between fibrosis grade and PA(P=0.355)or lean mass(P=0.378).There was a significant inverse correlation between the controlled attenuation parameter(CAP)and lean mass(P=0.378),positive correlation between PA and lean mass(P=0.378),and negative correlation between PA and fatty mass(P=0.378),although the CAP and PA were not correlated.When evaluated by sex,no significant correlations were found.CONCLUSION PA determines the muscle function of HIV/HCV-coinfected patients,and the CAP values reinforce the association with lean mass,suggesting that patients require early nutritional interventions.
基金founded by Wu Jieping Medical Foundation(No.320.6750.19001).
文摘Bioelectrical impedance analysis(BIA)is a noninvasive and reproducible technique for assessing changes in body composition and nutritional status.The phase angle(PA),a major parameter of BIA,is one of the most sensitive indicators used to detect malnutrition in patients,and is also a prognostic marker in various clinical diseases.The incidence of malnutrition in cancer patients is high,and malnutrition seriously affects the treatment process and prognosis of patients.Reasonable and effective nutritional interventions are therefore of great significance for cancer patients.Compared with traditional nutritional assessment tools,the PA has unique advantages in the nutritional assessment,efficacy monitoring and prognostic prediction of patients with malignant tumors,and it has broad application prospects in clinical practice.This article reviews the research progress on the application of the PA in patients with malignant tumors to provide clinicians with a tool to predict malnutrition,and provide a more favorable basis for the nutritional assessment,treatment and prognostic prediction of cancer patients.
基金supported by the science and technology project of State Grid Corporation of China (Security Protection Technology of Embedded Components and Control Units in Power System Terminal,No.5100-201941446A-0-0-00).
文摘Out-of-step oscillation separation devices based on apparent impedance angle trajectory are widely used in the power grid in China,and their reliability is of great importance.In this paper,the influence mechanism of series compensation on apparent impedance angle trajectory is analyzed.It reveals that series compensation capacitors reduce the equivalent impedance angle and consequently the apparent impedance angle cannot pass through all four zones,resulting in the risk of failure for the separation devices.A revised method of apparent impedance angle based on compensation principle is discussed,and then an improved out-of-step oscillation detection criterion is proposed.In view of the fact that the apparent impedance angle at the moment of maximum current is equal to the equivalent impedance angle during an oscillation process,a practical algorithm based on the compensated apparent impedance angle is proposed.RTDS tests are conducted to verify the effectiveness of the new criterion,considering transmission lines with a high series compensation level.
文摘Current and voltage waveforms recorded by intelligent electronic devices(IEDs)are more useful than just performing post-fault analysis.The objective of this paper is to present techniques to estimate the zero-sequence line impedance of all sections of a three-terminal line and the Thevenin equivalent impedance of the transmission network upstream from the monitoring location using protective relay data collected during short-circuit ground fault events.Protective relaying data from all three terminals may not be always available.Furthermore,the data from each terminal may be unsynchronized and collected at different sampling rates with dissimilar fault time instants.Hence,this paper presents approaches which use unsynchronized measurement data from all the terminals as well as data from only two terminals to estimate the zero-sequence line impedance of all the sections of a three-terminal line.An algorithm to calculate positive-,negative-and zero-sequence Thevenin impedance of the upstream transmission network has also been presented in this paper.The efficacy of the proposed algorithms are demonstrated using a test case.The magnitude error percentage in determining the zero-sequence impedance was less than 1%in the test case presented.
文摘With the increased penetration of non-conventionalrenewable energy resources, such as wind power plants (WPPs),into the power system, a lot of interest has been placed on studyingtheir impact for system protection, planning and operationsto ensure continued reliability of the electric grid. The impactof WPPs on the grid is typically identified during generationinterconnection studies. One of the challenges faced by protectionand planning engineers, at an early stage in this process, isthat many of the studies involving these power plants must beperformed without specific data available because the equipmentis not built yet. Among all the needed data, a particular interest inthis study is placed on the positive- and zero-sequence impedancesof the main power transformer (MPT) that interconnects a windpower plant to the transmission system due to its contribution toshort-circuit current during ground faults. The most commonlyfound in practice MPT winding configurations is a high-voltagewinding in wye with neutral bushing;a low-voltage windingin wye with neutral bushing without phase shift between thesewindings, and a stabilizing tertiary winding connected in deltathat is not designed for external loading designated as YNyn0+d.Thus, this paper proposes a methodology to estimate the sequenceimpedances of YNyn0+d transformers from a statistical point ofview applying clustering and regression analyses on existing MPTtest report data.
基金Scientific Research Project of Hunan Provincial Education Departmentgrant number:22C1326
文摘Objective: To investigate the diagnostic value of phase angle based on bioelectrical impedance method in senile sarcopenia. Methods: Clinical data from patients aged 60 and above who received treatment in our hospital from January 2023 to January 2023 were retrospectively collected and analyzed. A total of 214 cases were divided into two groups based on the presence or absence of sarcopenia. The baseline data of the two groups were compared, and multiple regression analysis was conducted to identify the independent risk factors of sarcopenia in the elderly. Additionally, the diagnostic effect of phase angle on sarcopenia in the elderly was assessed using the ROC curve analysis. Results: A total of 214 cases were included, of which 103patients(48.131%) were diagnosed with sarcopenia, while the remaining 111 patients(51.869%) with non-sarcopenia. The results showed that the age of sarcopenia group was significantly higher than that of non-sarcopenia group(P<0.05). Additionally, total body moisture, protein, inorganic salts, body fat, phase angle, skeletal muscle mass index, grip strength and 6-m pace were significantly lower in sarcopenia group than those in non-sarcopenia group(P<0.05). Correlation and regression analyses identified phase angle, BMI, total body moisture, and body fat as independent risk factors for sarcopenia in the elderly(OR >1). ROC curve analysis showed that the areas under AUC for the phase angle, BMI, total body moisture, and body fat AUC were 0.762,0.650, 0.685, and 0.660, respectively. The highest combined diagnostic AUC was 0.865,indicating that the combined diagnosis had a better diagnostic effect on sarcopenia in the elderly. Conclusion: Phase angle serves as an effective index for detecting sarcopenia in the elderly, which can effectively evaluate muscle mass and muscle strength. It suggests that phase angle as an easy-to-monitor indicator is conductive to a more accurate and convenient diagnosis of sarcopenia.
文摘针对顺北超深层碳酸盐岩断控缝洞型储集体储层非均质性强、地震资料信噪比低、叠后储层预测精度不足及裂缝识别困难等问题,基于五维地震数据,探索了提高裂缝型储层预测精度的新方法。在研究顺北断控缝洞型油气藏储层发育特征的基础上,开展了五维地震各向异性正演模拟,建立了地震振幅与裂缝参数的关系,并优选了裂缝预测敏感参数;在此基础上推导出傅里叶级数形式的方位弹性阻抗方程,开展了裂缝型储层预测,并在顺北X井区进行了应用。研究结果明确了超深层碳酸盐岩断控储集体的AVAZ(amplitude variation with azimuth and offset)地震响应特征,指出裂缝密度是指示裂缝型储层的敏感参数;同时,利用二阶傅里叶系数表征了裂缝发育密度,在顺北X井区实现了裂缝型储层的精细表征,预测吻合率较高。基于振幅属性的五维地震预测技术通过挖掘宽方位地震数据的振幅、方位信息,丰富了裂缝发育密度和方向等相关信息的预测。建立的傅里叶系数-裂缝密度映射关系为断控缝洞型油藏预测提供了定量化工具,为断控缝洞型油藏裂缝预测及目标评价提供了新的思路。
