Evaluation of Lightning Electromagnetic Fields and Their Induced Voltages on Overhead Lines Considering the Frequency Dependence of Soil Electrical Parameters

2013 ◽  
Vol 55 (6) ◽  
pp. 1210-1219 ◽  
Author(s):  
Majed Akbari ◽  
Keyhan Sheshyekani ◽  
Abolfazl Pirayesh ◽  
Farhad Rachidi ◽  
Mario Paolone ◽  
...  
2019 ◽  
Vol 21 (1) ◽  
pp. 152 ◽  
Author(s):  
Olga García-Minguillán ◽  
Raquel Prous ◽  
Maria del Carmen Ramirez-Castillejo ◽  
Ceferino Maestú

The effects produced by electromagnetic fields (EMFs) on human beings at extremely low frequencies (ELFs) have being investigated in the past years, across in vitro studies, using different cell lines. Nevertheless, the effects produced on cells are not clarified, and the cellular mechanisms and cell-signaling processes involved are still unknown. This situation has resulted in a division among the scientific community about the adequacy of the recommended level of exposure. In this sense, we consider that it is necessary to develop long-term exposure studies and check if the recommended levels of EMFs are under thermal effects. Hence, we exposed CT2A cells to different EMFs at different ELFs at short and long times. Our results showed frequency dependence in CT2A exposed during 24 h to a small EMF of 30 μT equal to those originated by the Earth and frequency dependence after the exposure during seven days to an EMF of 100 µT at different ELFs. Particularly, our results showed a remarkable cell viability decrease of CT2A cells exposed to EMFs of 30 Hz. Nevertheless, after analyzing the thermal effects in terms of HSP90 expression, we did not find thermal damages related to the differences in cell viability, so other crucial cellular mechanism should be involved.


1983 ◽  
Vol 10 (3) ◽  
pp. 353 ◽  
Author(s):  
TC Chilcott ◽  
HGL Coster ◽  
K Ogata ◽  
JR Smith

The water-film technique has been used to measure the frequency dependence of the membrane capacitance and conductance as a function of position along illuminated cells of C. australis. At low frequencies (< 1 Hz) the behaviour of the membrane capacitance was found to be strongly dependent upon both frequency and position. A complicated oscillatory pattern was observed which is possibly linked to interference effects between the impressed alternating current and the current normally circulating between alternate acid and alkaline zones. The area-specific membrane conductance was always higher in the alkaline zones than in the acid zones and at low frequencies was 0.45 - 1.3 S m-2 and 2.9 - 3.6 S m-2 respectively. The temperature dependence of the variation of the capacitance and conductance with frequency was also different in the acid and alkaline zones. The observed spatial and frequency dependence of the membrane electrical parameters is clearly associated with the dynamic homeostatis of the cell, and has consequences for the construction of realistic electrical models for the membrane of C. australis.


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