Progress in the Knowledge, Application and Influence of Extremely Low Frequency Signals

Round 1

Reviewer 1 Report

The paper presents a very thorough survey in the research areas related to ELF. It covers a large number papers focusing on a variety of different applications. I think the paper is well organized and well presented. I recommend acceptance for this paper. Below please find a few minor comments that I think can help improve the overall quality of the paper:

• This paper addresses an important topic of ELF signals which appears to have an inconsistent definition in the paper. In line 35, ELF is defined in the frequency range of 3 hz to 3 KHz. However, in line 119, it is defined in the frequency range of 3-300 Hz. Please clarifiy
• Although the paper already covers many published work, it seems there is one important area that is missing from the paper: ELF communications. ELF has many great applications in long distance communications, particularly in the military communications. One example is to use ELF to communicate to submarine from the surface (https://fas.org/nuke/guide/usa/c3i/elf.htm). Many papers have been published to study the generating, propagation, and receiving ELF waves for this particular application. Recently, ELF has found its application in emergence communications following a mining disaster whenever all other communication systems tend to fail. An example of the papers in ELF through the earth communications is: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5701283/

Of course this is just an example, I’m sure authors can find many similar papers studying the earth overburden as a propagation channel at ELF frequencies, how to best generate and receive ELF signals by injecting and receiving ELF signals from the earth. It should be noted that there are another body of publications in using magnetic fields rather than electrical fields for communications at the ELF frequency range.

Author Response

The paper presents a very thorough survey in the research areas related to ELF. It covers a large number papers focusing on a variety of different applications. I think the paper is well organized and well presented. I recommend acceptance for this paper.

The authors would like to thank you for your valuable comments that have allowed us to improve the document.

Below please find a few minor comments that I think can help improve the overall quality of the paper:

• This paper addresses an important topic of ELF signals which appears to have an inconsistent definition in the paper. In line 35, ELF is defined in the frequency range of 3 hz to 3 KHz. However, in line 119, it is defined in the frequency range of 3-300 Hz. Please clarifiy.

Thank you for your comment. There is no uniformity of criteria among the authors, as one defines it as 3-300Hz and others go up to 3kHz, others start at 30 Hz up to 300 Hz or 3kHz. We consider them in our studies from 3 to 300 Hz for detection, since the first peak of the Schuman Resonance is at 7 Hz and is one of the applications of the ELF Wave, the detection of "the health of  the Earth" among other considerations. To unify we will use the recommendations "recommendation ITU-R v.431-8 Nomenclature of the frequency and wavelength bands  used in telecommunications" of The International Telecommunication Union (ITU), it has been changed to 0.3 to 300 Hz and we avoid confusing the readers.

• Although the paper already covers many published work, it seems there is one important area that is missing from the paper: ELF communications. ELF has many great applications in long distance communications, particularly in the military communications. One example is to use ELF to communicate to submarine from the surface (https://fas.org/nuke/guide/usa/c3i/elf.htm). Many papers have been published to study the generating, propagation, and receiving ELF waves for this particular application. Recently, ELF has found its application in emergence communications following a mining disaster whenever all other communication systems tend to fail. An example of the papers in ELF through the earth communications is: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5701283/

Of course this is just an example, I’m sure authors can find many similar papers studying the earth overburden as a propagation channel at ELF frequencies, how to best generate and receive ELF signals by injecting and receiving ELF signals from the earth. It should be noted that there are another body of publications in using magnetic fields rather than electrical fields for communications at the ELF frequency range.

Thank you for your comment. The document has been expanded, considering the references indicated.

Line 522: “ELF communications have been very important in recent years and continue to be researched today. These communications are very long distance, as they involve large wavelengths and have been applied in very diverse fields, among which military communications stand out. An example of this is the application of this type of wave for communication between fixed stations and submerged submarines [89]. Many works have been developed and published based on the study of the generation, propagation and reception of ELF waves, since their discovery in the middle of the 20th century. Recently these communications have been used for emergency situations after natural or mining disasters [90], where other usual communication systems would not work.”.

The following references have been added:

[89]     T. U. S. Navy, “Extremely Low Frequency Transmitter Site Clam Lake, Wisconsin,” Navy Fact file, pp. 1–4, 2001.

[90]     N. Kumar, P. C. Panchariya, K. Srinath, and P. Bhanu Prasad, “Hybrid mine wide communication system for surveillance and safety of the miners in underground coal mines,” in Proceedings of the 2013 International Conference on Advanced Electronic Systems, ICAES 2013, 2013, pp. 262–266.

Reviewer 2 Report

This paper resumes the research in the field of ELF (Extremely Low Frequency) between 1957 to 2019. I find this paper appropriate and recommend for publication provided that the authors attend the suggested manuscript changes.

 

1)

Line 93-95: The authors address the relationship between exposure to ELF fields and the risk of development of cancer cells. Yet, the authors need to address the bidirectionality of these signals. Cancer cells, such as glioma, prostate cancer and human breast cancer cells also generate ELF and this needs to be discussed, or at least referenced. Important literature to reference is: Ribeiro M, et al., Human Breast Cancer Cells Demonstrate Electrical Excitability, Frontiers in Neuroscience (2020), Rocha P., et al., Extracellular electrical recording of pH-triggered bursts in C6 glioma cell populations, Science Advances (2016) and Cabello, M., et al, Extracellular electrophysiology in the prostate cancer cell model PC-3, Sensors (2019).

This section could be linked to Line 291 when authors discuss the Electrophysiological effects community.

 

3)

The sentence written in Line 316 is incomplete. When the authors write: “From [34] it is extracted that for the exposure to these ELF fields to be evaluated, the fact that the exposure is imperceptible, has multiple sources and may vary according to time and distance should be considered.” Extraction of low frequency signals does not occur naturally. Several approached are being considered in literature. In this contribution the authors should cite recent work on energy harvesting from multiple low frequency sources such as: Wang X., et al., An Energy Harvester for Low‐Frequency Electrical Signals, Energy Technology (2020).

 

4)

Line 312 should not start with a reference number. Please revise.

 

Author Response

This paper resumes the research in the field of ELF (Extremely Low Frequency) between 1957 to 2019. I find this paper appropriate and recommend for publication provided that the authors attend the suggested manuscript changes.

The authors would like to thank you for your valuable comments that have allowed us to improve the document.

Line 93-95: The authors address the relationship between exposure to ELF fields and the risk of development of cancer cells. Yet, the authors need to address the bidirectionality of these signals. Cancer cells, such as glioma, prostate cancer and human breast cancer cells also generate ELF and this needs to be discussed, or at least referenced. Important literature to reference is: Ribeiro M, et al., Human Breast Cancer Cells Demonstrate Electrical Excitability, Frontiers in Neuroscience (2020), Rocha P., et al., Extracellular electrical recording of pH-triggered bursts in C6 glioma cell populations, Science Advances (2016) and Cabello, M., et al, Extracellular electrophysiology in the prostate cancer cell model PC-3, Sensors (2019).

This section could be linked to Line 291 when authors discuss the Electrophysiological effects community.

Thank you for your comment. The author's contributions have been considered and studied and the references provided.

Line 448: “The study of the interaction of ELF fields and living systems, as well as the risk of developing cancer cells has been extensively researched in the last decade, one example being [57]. The bidirectionality of these signals should also be considered. Studies have been established that consider that cancer cells such as glioma or different types of cancers generate ELF waves. In established studies of glioma patients, epileptic seizures are often seen due to the impact of the tumor on the physiology of the brain. This unexpected electrical activity can disrupt the functionality of the healthy neural network in the vicinity of the tumor mass and may contribute to seizures [79]. Breast cancer is one of the most common cancers worldwide, although its pathophysiology is poorly understood. Numerous single-cell electrophysiological studies have been developed, suggesting a link between bioelectricity and cell invasiveness. A pattern of activity with characteristics like those of random telegraph signal (RTS) noise [80] has also been recorded. A similar fact is observed in prostate cancer, one of the most common cancers in the male population, where its basic biological function at the cellular level is not yet fully known. In [81] the measurement and characterization of the electrical activity of PC-3 prostate cancer cell populations is presented, demonstrating for the first time the existence of a significant electrical pattern. This type of recordings allows for the establishment of new, highly sensitive, real-time research pathways for the development of new, more specific and effective treatment strategies.”.

 The following references have been added:

[79]     P. R. Rocha et al., “Extracellular electrical recording of pH-triggered bursts in C6 glioma cell populations,” Sci. Adv., vol. 2, no. 12, pp. 1–9, 2016.

[80]     M. Ribeiro et al., “Human Breast Cancer Cells Demonstrate Electrical Excitability,” Front. Neurosci., vol. 14, no. April, pp. 1–10, 2020.

[81]     M. Cabello et al., “Extracellular electrophysiology in the prostate cancer cell model PC-3,” Sensors (Switzerland), vol. 19, no. 1, pp. 1–11, 2019.

 3) The sentence written in Line 316 is incomplete. When the authors write: “From [34] it is extracted that for the exposure to these ELF fields to be evaluated, the fact that the exposure is imperceptible, has multiple sources and may vary according to time and distance should be considered.” Extraction of low frequency signals does not occur naturally. Several approached are being considered in literature. In this contribution the authors should cite recent work on energy harvesting from multiple low frequency sources such as: Wang X., et al., An Energy Harvester for Low‐Frequency Electrical Signals, Energy Technology (2020).

Thank you for your comment. The aspect suggested by the author has been considered and new references related to the subject have been studied.

Line 323 :“In addition, the extraction of low frequency signals does not occur naturally. There are numerous approaches to generating or collecting power from multiple low frequency sources in the literature. These ecological generators convert the low-frequency mechanical shaking of ocean waves [60] or human motion [61] into alternating low-frequency electrical signals for energy collectors. One such energy collector, developed at [62], allows efficient energy collection from low frequency voltage pulses, such as those typically generated by triboelectric or piezoelectric generators.”.

The following references have been added:

[60]     U. T. Jurado, S. H. Pu, and N. M. White, “Dielectric-Metal Triboelectric Nanogenerators for Ocean Wave Impact Self-Powered Applications,” IEEE Sens. J., vol. 19, no. 16, pp. 6778–6785, 2019.

[61]     Q. Guan et al., “Highly efficient self-healable and dual responsive hydrogel-based deformable triboelectric nanogenerators for wearable electronics,” J. Mater. Chem. A, vol. 7, no. 23, pp. 13948–13955, 2019.

[62]     X. Wang et al., “An Energy Harvester for Low Frequency Electrical Signals,” Energy Technol., pp. 1–17, 2020.

  4) Line 312 should not start with a reference number. Please revise.

Thank you for your comment. We understand that it refers to line 321, has been modified by “Jan Walleczek (1992) presents a review of the knowledge about the effects of non-thermal levels of ELF electromagnetic fields on the biochemistry and activity of immune cells [63].”, on the current line 334.

Reviewer 3 Report

This paper examined the ELF-related literature published between 1957 and 2019, divided them into nine communities and reported their details.

This work is interesting to a wider audience.

 

I have one comment.

I thought that if you show the changes over time in each community,

you can predict the research theme that will become more active in the future.

 

Author Response

This paper examined the ELF-related literature published between 1957 and 2019, divided them into nine communities and reported their details.

This work is interesting to a wider audience.

The authors would like to thank you for your valuable comments that have allowed us to improve the document.

 I have one comment. I thought that if you show the changes over time in each community, you can predict the research theme that will become more active in the future.

Thank you for your comment. The document has been expanded.

Line 882: “These small communities are considered emerging communities where the greatest progress has been made, as most have appeared and fully developed in the last decade. An example of this is the community where the biological effects of ELF fields on crops are studied, where most of the papers have been published between 2008 [103] and 2014 [123]. These papers consider the exposure to ELF fields in different crops, which may be a discriminating factor for their growth. A similar fact occurs in the smaller community studied, the one related to the UELF spectrum. This community is formed by a small number of works developed since 2017 [124], so it is a very recent and little researched topic. These are some of the reasons why these communities raise the possibility of developing many future works and research. The subject studied has great potential and can be applied to many fields, giving rise to a great deal of research and international publications of great interest.”.

The following references have been added:

[123]    R. He, G. Xi, and K. Liu, “Alleviating effect of extremely low frequency pulsed electric field on drought damage of maize seedling roots,” J. Lumin., vol. 188, no. April, pp. 441–447, 2017.

[124]    A. Salcedo, “The longest classical EM waves in the Universe: Communications carriers that are larger than Earth,” in International Conference on Electronics, Communications and Computers (CONIELECOMP), 2017.

Reviewer 4 Report

Dear Authors,

your manuscript is very interesting and important, but in my opinion it is a bit too technical. This is maybe the reason, why you didn't mention about children leukemia in relation to the power lines vicinity. Probably papers, which discussed this problem are not so many times cited, but risk of children leukemia is recognized as very important  for citizens living near these lines. In you paper this problem is absent. Readers, who are not familiar with the health effects of the ELF EMF won't know about such a risk. I suggest to add  a few sentences on this topic

Minor remarks:

There is a surprised form of citation, without names of citied authors, only number of reference for example: [67] presents a review of the knowledge about the effects of non-thermal. Most often another form is used: J. Walleczek (1992) presents....[67] (the number on the end of the sentence)

Title of the Table 1 is not in English

Author Response

Your manuscript is very interesting and important, but in my opinion it is a bit too technical. This is maybe the reason, why you didn't mention about children leukemia in relation to the power lines vicinity. Probably papers, which discussed this problem are not so many times cited, but risk of children leukemia is recognized as very important for citizens living near these lines. In you paper this problem is absent. Readers, who are not familiar with the health effects of the ELF EMF won't know about such a risk. I suggest to add a few sentences on this topic.

The authors would like to thank you for your valuable comments that have allowed us to improve the document.

Line 701: “Several research studies have been published studying the control of childhood cancer, commonly leukaemia, and exposure to fields derived from lines at 60 Hz [106]. The evaluation of the effect of fields derived from these lines showed significant elevations in the risk of high exposure to them [107].”.

The following references have been added:

[106]    J. E. Deadman, B. G. Armstrong, M. L. McBride, R. Gallagher, and G. Thériault, “Exposures of children in Canada to 60-Hz magnetic and electric fields,” Scand. J. Work. Environ. Heal., vol. 25, no. 4, pp. 368–375, 1999.

[107]    A. B. Miller, T. To, D. A. Agnew, C. Wall, and L. M. Green, “Leukemia following occupational exposure to 60-Hz electric and magnetic fields among Ontario electric utility workers,” Am. J. Epidemiol., vol. 144, no. 2, pp. 150–160, 1996.

 Minor remarks: There is a surprised form of citation, without names of citied authors, only number of reference for example: [67] presents a review of the knowledge about the effects of non-thermal. Most often another form is used: J. Walleczek (1992) presents....[67] (the number on the end of the sentence)

Thank you for your comment. We have been modified by “Jan Walleczek (1992) presents a review of the knowledge about the effects of non-thermal levels of ELF electromagnetic fields on the biochemistry and activity of immune cells [63].”, on the current line 334.

Title of the Table 1 is not in English

Thank you for your comment. The text has been replaced by: “Table 1. Top 20 most important authors by H-Index.”.

Round 2

Reviewer 2 Report

I recommend this current version for publication