Magnetic resonance imaging based kidney volume assessment for risk stratification in pediatric autosomal dominant polycystic kidney disease

IntroductionIn the pediatric context, most children with autosomal dominant polycystic kidney disease (ADPKD) maintain a normal glomerular filtration rate (GFR) despite underlying structural kidney damage, highlighting the critical need for early intervention and predictive markers. Due to the inverse relationship between kidney volume and kidney function, risk assessments have been presented on the basis of kidney volume. The aim of this study was to use magnetic resonance imaging (MRI)-based kidney volume assessment for risk stratification in pediatric ADPKD and to investigate clinical and genetic differences among risk groups.MethodsThis multicenter, cross-sectional, and case-control study included 75 genetically confirmed pediatric ADPKD patients (5–18 years) and 27 controls. Kidney function was assessed by eGFR calculated from serum creatinine and cystatin C using the CKiD-U25 equation. Blood pressure was assessed by both office and 24-hour ambulatory measurements. Kidney volume was calculated from MRI using the stereological method. Total kidney volume was adjusted for the height (htTKV). Patients were stratified from A to E classes according to the Leuven Imaging Classification (LIC) using MRI-derived htTKV.ResultsMedian (Q1-Q3) age of the patients was 6.0 (2.0–10.0) years, 56% were male. There were no differences in sex, age, height-SDS, or GFR between the patient and control groups. Of the patients, 89% had PKD1 and 11% had PKD2 mutations. Non-missense mutations were 73% in PKD1 and 75% in PKD2. Twenty patients (27%) had hypertension based on ABPM. Median htTKV of the patients was significantly higher than controls (141 vs. 117 ml/m, p = 0.0003). LIC stratification revealed Classes A (38.7%), B (28%), C (24%), and D + E (9.3%). All children in class D + E and 94% in class C had PKD1 variants. Class D + E patients had significantly higher blood pressure values and hypertension compared to other classes (p > 0.05 for all).DiscussionThis study distinguishes itself by using MRI-based measurements of kidney volume to stratify pediatric ADPKD patients into specific risk groups. It is important to note that PKD1 mutation and elevated blood pressure were higher in the high-risk groups stratified by age and kidney volume. Our results need to be confirmed in further studies

Simulation of transient processes on overvoltage in electric transmission lines using ATP-EMTP

In this paper, the mathematical modeling and simulation of electromagnetic transient processes is considered, which is of vital importance for examining the overvoltage phenomenon of power transmission systems. In the mathematical models of the AC power transmission systems that contain a power source, the power transformer, transmission line, and power autotransformer block are presented. The mathematical model of each system component is obtained based on the branch voltages, flux linkages, and branch voltages of the magnetic circuits individually. As for the simulation, an alternative transient program (ATP) environment is used to model the electric power system's elements. One of the power system's overvoltages occurs because of the fault and switching events. The usage of reactors at the sending and receiving ends of the line limits the overvoltages. The ATP has a powerful tool to simulate the transient events: speci fi cally, the fault transients in the time domain. In order to test the simulation model's performance, the overvoltage measurements from a fi eld test of a 500 kV electric transmission system is used. The simulation shows that the obtained results give satisfactory solutions to investigate the power system's overvoltage events. Selected results of the evaluation are presented

Coherence analysis and transfer function model for ceramic plate vibrations

Correlations on the state of ceramic plates, that are either intact or cracked, are performed through the data obtained. In the analysis the frequency range of coherence has been identified in the form of the two regions. Low-frequency region is spectral amplitude that is below the threshold defined by the level of coherence about 0.2, which is on the level of little correlation. This region is in the frequency range of approximately 0-28 kHz. In this frequency range a weak correlation between the spectra of solid ceramic plates and cracked ones is observed

Investigation of short-circuit and ground faults in a system fed with a wind turbine

In this study, short circuit and ground failures in Electric Transmission Line (ETL) that is supplied by this wind system are investigated The curves obtained from these failures are interpreted through analysis. The mathematical model of wind turbine and generator is prepared and the results obtained from the simulation are evaluated. The short-circuit and ground fault analyzes were performed separately for each of the three phases. ATP-EMTP program is used in the analysis and the results obtained were found to be quite compatible

RESEARCH AND PROTECTION OF ENERGY TRANSMISSION LINES FROM THE FERRORESONANCE OVERVOLTAGES

This paper focuses on ferroresonance overvoltage in energy transmission lines. Ferroresonance is an oscillation in a non-linear series resonance circuit, which shows overvoltage and overcurrent waveforms with significant distortion. The high voltage equipments may be damaged due to dielectric and thermal problems of Ferroresonance. One of the problems of energy transmission lines is that they need to be protected from ferroresonance overvoltage. In this article, the overvoltage of energy transmission lines is investigated. In order to abolish the overvoltage the ways of using reactors in the beginning and at the end of energy transmission lines are shown. A very comprehensive analysis is performed using time domain simulations with ATP (Alternative Transient Program). Simulation results reproduced satisfactorily the ferroresonant events recorded during the field tests in the 500 kV. energy transmission lines. A number of mitigation options are discussed