# Sensitivity of Cell Cultures on Time-Varying Low-Frequency Magnetic Field Changes
## 4 Conclusions  
The research presented within this paper extends and complements the previously published article [29], which was focused almost exclusively on experimental system design, construction, and testing. Herein, the experimental methodology is the same as in [29], but the main attention is focused on the application of a designed and developed system in terms of conducting a statistically relevant number of experiments performed by changes of specific physical parameters of applied ELF MF, with the intention to verify the resonant nature of the observed biological reaction. The relevance of the presented results is tested through various statistical analysis methods, providing a completely new overview of the investigations.  
The first series of experiments aimed to verify the sensitivity of the biological system response in the vicinity of the resonance point for calcium ions \(f_{\mathrm{C}}^{Ca^{2+}}=29.89\) Hz, with a specified range of \(\pm 5\) Hz and the magnetic flux density ratio \(B_{\mathrm{AC}}/B_{\mathrm{DC}}=1.8\). The frequency of the applied field was determined based on the IPR theory, and the magnetic flux density of the geomagnetic field was obtained by measurements at the location where the experiments were carried out. The magnetic flux density ratio was chosen based on the published results of other research groups [23; 24], where the maximum biological effect was observed at a precise mutual \(B_{\mathrm{AC}}/B_{\mathrm{DC}}\) ratio setting. The statistical evaluation of the results confirmed the influence of the frequency change on the biological system response but did not support the hypothesis regarding the maximum response of the system at the cyclotron resonance frequency for calcium ions. Instead, the maximum effect was observed at a frequency of 34.89 Hz and a frequency of 24.89 Hz at a given \(B_{\mathrm{AC}}/B_{\mathrm{DC}}\) ratio.  
The second series of experiments verify the response of the biological system depending on the ratio of the alternating and direct components of the magnetic flux density. The works [12; 23; 24] published so far assumed the maximum effect of the applied field at \(B_{\mathrm{AC}}/B_{\mathrm{DC}}=1.8\) and further decreasing maxima at ratios of 0.7; 0.9; 1.3; 1.6; 2.1; 2.8; 3.4. The statistical evaluation of the results showed that the change in the magnetic flux density ratio does not have a significant effect on the mean value of the effect rate--the response of the biological system.  
Based on our preliminary results, the validity of the two requirements of IPR theory cannot be unequivocally confirmed or refuted. The research in the subject area requires further investigation. It is necessary to perform a more significant number of experiments. In any case, it can be concluded that at least there is an indication of a frequency-dependent exposure effect of ELF MF at the cellular level, confirming other preliminary observations from [34; 35].  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13031777/s1](https://www.mdpi.com/article/10.3390/app13031777/s1)]([https://www.mdpi.com/article/10.3390/app13031777/s1](https://www.mdpi.com/article/10.3390/app13031777/s1)), Figure S1: Average YPD temperature difference between control and exposed samples A-E; Figure S2: Ambient temperature monitoring within the incubator during the experiment.  
Conceptualization, [PERSON]; Methodology, Z.J.; Investigation, Z.J. and R.R.; Software, Z.J.; Validation, Z.J. and I.P.; Writing--Original Draft Preparation, Z.J.; Writing--Review & Editing, R.R. and L.J.; Visualization, Z.J.; Supervision, [PERSON]; Data Curation, I.P. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Slovak Research and Development Agency under the Contract no. APVV-19-0214.  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflict of interest.