# Progress in the Knowledge, Application and Influence of Extremely Low Frequency Signals
## 3 Results and Discussion
(**b**) Representation of the distribution of works in each community. Figure 2: Representation of the distribution of the works in each of the communities. community, with the ELF-1 in cancer community being almost 1.5% more researched than the ELF-1 in the brain community. The ELF-1 in cancer community relates to the general community (ELF transcription factors community) through work [46] which investigates a protein that interacts with the ELF gene, and that plays a key role in suppressing gastric carcinoma. The connection comes from the fact that some of the authors of this work have carried out other research present in the general community. Forty percent of the works of this community are published in journals related to cancer oncology and is research carried out in the last 20 years, from 1999 to 2019. The main theme of these publications is the relationship of the ELF1 gene with the development of various cancers. A relationship of this gene with cellular liver cancer has been established [47], and pancreatic cancer [48] and gastric cancer [49]. The articles constituting this community have a high number of references, as is the case of the most important work according to the nodes [50], published 3 years ago and with 202 references. For its part, the ELF-1 community in the brain is related to the larger community through publication [51], where different genes present in the chick's retina are analyzed for vision in myopic blur conditions. The ELF1 gene is involved in the regulation of the vision system, together with other transcription factors, thus relating to other articles of the general community (ELF transcription factors). In the ELF-1 in the brain community, aspects derived from the ELF-1 gene in brain functions are considered, treating aspects such as the cloning of this gene [52], its topographic effects on the axon guide of the retina [53], or its importance in the hippocampus of the brain [54]. Most of the publications have many references in Scopus, the most important document by nodes [55] has 632 references. After analyzing these three communities, they were discarded from the initial search when considering a theme that differs markedly from that existing in the rest of the communities, since it does not relate to ELF waves in any of its possible variants or applications. This is one reason showing that a search should not be established using only the keywords, since this fact does not guarantee that all the found documents belong to the same theme. It is vitally important to establish a detailed analysis of the communities found after the purification processes, to guarantee the effectiveness of the search performed. The communities that really investigate ELF waves are represented in Figure 4. Considering that those formed by less than 2% of the total documents are represented together in black, under the heading \"Other Communities\". There are two communities that stand out for their size compared to the rest, the communities ELF in health and the lightning ELF phenomena. The ELF in health community have the largest publication percentage (58.50%) and show the highest concentration of related nodes. The lightning ELF phenomena community, publishing 20.06% of the total number of works, comes second in size and is related to nodes from other communities such as the ELF wave generation community or the natural ELF phenomena community. Figure 4: Representation of the communities investigating ELF waves. Figure 5 shows the 20 global keywords that appear the most in the communities studied. The most repeated word was \"extremely low frequency\", one of the words used for the search with 509 repetitions, the following words were \"electromagnetic fields\" with 440 repetitions, followed by \"magnetic field\" and \"extremely low frequency-electromagnetic field\" with 358 and 252 repetitions respectively. All these words were among the 10 most-repeated keywords in almost all communities, considering them as general words.