{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T01:17:57Z","timestamp":1760231877444,"version":"build-2065373602"},"reference-count":46,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2022,5,20]],"date-time":"2022-05-20T00:00:00Z","timestamp":1653004800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Faculty of Technical Sciences, University of Novi Sad, Serbia","award":["(PRJ-0167) 2017WZFTZP"],"award-info":[{"award-number":["(PRJ-0167) 2017WZFTZP"]}]},{"name":"Italian MIUR","award":["(PRJ-0167) 2017WZFTZP"],"award-info":[{"award-number":["(PRJ-0167) 2017WZFTZP"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>This work investigates the temporal statistical structure of time series of electric field (EF) intensity recorded with the aim of exploring the dynamical patterns associated with periods with different human activity in urban areas. The analyzed time series were obtained from a sensor of the EMF RATEL monitoring system installed in the campus area of the University of Novi Sad, Serbia. The sensor performs wideband cumulative EF intensity monitoring of all active commercial EF sources, thus including those linked to human utilization of wireless communication systems. Monitoring was performed continuously during the years 2019 and 2020, allowing us to investigate the effects on the patterns of EF intensity of varying conditions of human mobility, including regular teaching and exam activity within the campus, as well as limitations to mobility related to the COVID-19 pandemic. Time series analysis was performed using both simple statistics (mean and variance) and combining the information-theoretic measure of information storage (IS) with the method of surrogate data to quantify the regularity of EF dynamic patterns and detect the presence of nonlinear dynamics. Moreover, to assess the possible coexistence of dynamic behaviors across multiple temporal scales, IS analysis was performed over consecutive observation windows lasting one day, week, month, and year, respectively coarse grained at time scales of 6 min, 30 min, 2 h, and 1 day. Our results document that the EF intensity patterns of variability are modulated by the movement of people at daily, weekly, and monthly scales, and are blunted during periods of restricted mobility related to the COVID-19 pandemic. Mobility restrictions also affected significantly the regularity of the EF intensity time series, resulting in lower values of IS observed simultaneously with a loss of nonlinear dynamics. Thus, our analysis can be useful to investigate changes in the global patterns of human mobility both during pandemics or other types of events, and from this perspective may serve to implement strategies for safety assessment and for optimizing the design of networks of EF sensors.<\/jats:p>","DOI":"10.3390\/e24050726","type":"journal-article","created":{"date-parts":[[2022,5,20]],"date-time":"2022-05-20T13:56:12Z","timestamp":1653054972000},"page":"726","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Information Dynamics of Electric Field Intensity before and during the COVID-19 Pandemic"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7409-8130","authenticated-orcid":false,"given":"Gorana","family":"Mijatovic","sequence":"first","affiliation":[{"name":"Faculty of Technical Sciences, University of Novi Sad, 21102 Novi Sad, Serbia"}]},{"given":"Dragan","family":"Kljajic","sequence":"additional","affiliation":[{"name":"Faculty of Technical Sciences, University of Novi Sad, 21102 Novi Sad, Serbia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1502-450X","authenticated-orcid":false,"given":"Karolina","family":"Kasas-Lazetic","sequence":"additional","affiliation":[{"name":"Faculty of Technical Sciences, University of Novi Sad, 21102 Novi Sad, Serbia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1725-3405","authenticated-orcid":false,"given":"Miodrag","family":"Milutinov","sequence":"additional","affiliation":[{"name":"Faculty of Technical Sciences, University of Novi Sad, 21102 Novi Sad, Serbia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9800-9211","authenticated-orcid":false,"given":"Salvatore","family":"Stivala","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Palermo, 90128 Palermo, Italy"}]},{"given":"Alessandro","family":"Busacca","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Palermo, 90128 Palermo, Italy"}]},{"given":"Alfonso Carmelo","family":"Cino","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Palermo, 90128 Palermo, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5873-8564","authenticated-orcid":false,"given":"Sebastiano","family":"Stramaglia","sequence":"additional","affiliation":[{"name":"Department of Physics, University of Bari, 70121 Bari, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3271-5348","authenticated-orcid":false,"given":"Luca","family":"Faes","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Palermo, 90128 Palermo, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,20]]},"reference":[{"key":"ref_1","unstructured":"Presman, A. (2013). Electromagnetic Fields and Life, Springer Science & Business Media."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Goldsmith, A. (2005). Wireless Communications, Cambridge University Press.","DOI":"10.1017\/CBO9780511841224"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Wong, V.W., Schober, R., Ng, D.W.K., and Wang, L.C. (2017). Key Technologies for 5G Wireless Systems, Cambridge University Press.","DOI":"10.1017\/9781316771655"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"134","DOI":"10.1109\/MNET.001.1900287","article-title":"A vision of 6G wireless systems: Applications, trends, technologies, and open research problems","volume":"34","author":"Saad","year":"2019","journal-title":"IEEE Netw."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"871","DOI":"10.1109\/TBCAS.2013.2245664","article-title":"MedMon: Securing medical devices through wireless monitoring and anomaly detection","volume":"7","author":"Zhang","year":"2013","journal-title":"IEEE Trans. Biomed. Circuits Syst."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1109\/MWC.2018.1800229","article-title":"Is 5G ready for drones: A look into contemporary and prospective wireless networks from a standardization perspective","volume":"26","author":"Salem","year":"2019","journal-title":"IEEE Wirel. Commun."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"188","DOI":"10.1109\/JIOT.2018.2884200","article-title":"Wireless toward the era of intelligent vehicles","volume":"6","author":"Cheng","year":"2018","journal-title":"IEEE Internet Things J."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Scientific Committee on Emerging Newly Identified Health Risks (2015). Opinion on potential health effects of exposure to electromagnetic fields. Bioelectromagnetics, 36, 480\u2013484.","DOI":"10.1002\/bem.21930"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"International Commission on Non-Ionizing Radiation Protection (ICNRP) (2020). Guidelines for limiting exposure to electromagnetic fields (100 KHz to 300 GHz). Health Phys., 118, 483\u2013524.","DOI":"10.1097\/HP.0000000000001210"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"779","DOI":"10.1038\/nature06958","article-title":"Understanding individual human mobility patterns","volume":"453","author":"Gonzalez","year":"2008","journal-title":"Nature"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1018","DOI":"10.1126\/science.1177170","article-title":"Limits of predictability in human mobility","volume":"327","author":"Song","year":"2010","journal-title":"Science"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"7332","DOI":"10.1073\/pnas.0610245104","article-title":"Structure and tie strengths in mobile communication networks","volume":"104","author":"Onnela","year":"2007","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Phithakkitnukoon, S., Smoreda, Z., and Olivier, P. (2012). Socio-geography of human mobility: A study using longitudinal mobile phone data. PLoS ONE, 7.","DOI":"10.1371\/journal.pone.0039253"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1029","DOI":"10.1126\/science.1186605","article-title":"Network diversity and economic development","volume":"328","author":"Eagle","year":"2010","journal-title":"Science"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1973","DOI":"10.1016\/S0140-6736(20)31142-9","article-title":"Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: A systematic review and meta-analysis","volume":"395","author":"Chu","year":"2020","journal-title":"Lancet"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1038\/s41598-021-90714-5","article-title":"Physical distancing and the perception of interpersonal distance in the COVID-19 crisis","volume":"11","author":"Welsch","year":"2021","journal-title":"Sci. Rep."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1016\/j.ins.2012.04.016","article-title":"Local measures of information storage in complex distributed computation","volume":"208","author":"Lizier","year":"2012","journal-title":"Inf. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1","DOI":"10.3389\/fninf.2014.00001","article-title":"Local active information storage as a tool to understand distributed neural information processing","volume":"8","author":"Wibral","year":"2014","journal-title":"Front. Neuroinform."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Kitzbichler, M.G., Smith, M.L., Christensen, S.R., and Bullmore, E. (2009). Broadband criticality of human brain network synchronization. PLoS Comput. Biol., 5.","DOI":"10.1371\/journal.pcbi.1000314"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"329","DOI":"10.1140\/epjb\/e2008-00175-0","article-title":"Predictive information and explorative behavior of autonomous robots","volume":"63","author":"Ay","year":"2008","journal-title":"Eur. Phys. J. B"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"277","DOI":"10.3390\/e17010277","article-title":"Information decomposition in bivariate systems: Theory and application to cardiorespiratory dynamics","volume":"17","author":"Faes","year":"2015","journal-title":"Entropy"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Faes, L., Porta, A., Nollo, G., and Javorka, M. (2017). Information decomposition in multivariate systems: Definitions, implementation and application to cardiovascular networks. Entropy, 19.","DOI":"10.3390\/e19010005"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"062114","DOI":"10.1103\/PhysRevE.95.062114","article-title":"Entropy measures, entropy estimators, and their performance in quantifying complex dynamics: Effects of artifacts, nonstationarity, and long-range correlations","volume":"95","author":"Xiong","year":"2017","journal-title":"Phys. Rev. E"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/0167-2789(92)90102-S","article-title":"Testing for nonlinearity in time series: The method of surrogate data","volume":"58","author":"Theiler","year":"1992","journal-title":"Phys. D Nonlinear Phenom."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"021906","DOI":"10.1103\/PhysRevE.71.021906","article-title":"Multiscale entropy analysis of biological signals","volume":"71","author":"Costa","year":"2005","journal-title":"Phys. Rev. E"},{"key":"ref_26","unstructured":"(2022, March 29). The EMF RATEL Internet Portal. Available online: https:\/\/emf.ratel.rs\/."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Djuric, N., Kavecan, N., Mitic, M., and Radosavljevic, N. (May, January 29). The EMF RATEL Service for Monitoring and Public Informing on EMF Exposure. Proceedings of the IEEE INFOCOM 2019-IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Paris, France.","DOI":"10.1109\/INFCOMW.2019.8845229"},{"key":"ref_28","unstructured":"(2022, May 03). Serbian Open Data Portal, Available online: https:\/\/data.gov.rs\/sr\/datasets\/rezultati-kontinualnog-merenja-nivoa-elektrichnog-polja-na-lokatsijama-od-interesa."},{"key":"ref_29","unstructured":"(2022, May 03). Serbian Open Data Portal. Available online: https:\/\/emf.ratel.rs\/getOpenData\/4\/csv."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1768264","DOI":"10.1155\/2017\/1768264","article-title":"Efficient computation of multiscale entropy over short biomedical time series based on linear state-space models","volume":"2017","author":"Faes","year":"2017","journal-title":"Complexity"},{"key":"ref_31","unstructured":"Nollo, G., Faes, L., Pellegrini, B., Porta, A., and Antolini, R. (2000, January 24\u201327). Synchronization index for quantifying nonlinear causal coupling between RR interval and systolic arterial pressure after myocardial infarction. Proceedings of the Computers in Cardiology 2000, (Cat. 00CH37163), Cambridge, MA, USA."},{"key":"ref_32","unstructured":"Cover, T.M. (1999). Elements of Information Theory, John Wiley & Sons."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"032115","DOI":"10.1103\/PhysRevE.99.032115","article-title":"Multiscale information storage of linear long-range correlated stochastic processes","volume":"99","author":"Faes","year":"2019","journal-title":"Phys. Rev. E"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"H2039","DOI":"10.1152\/ajpheart.2000.278.6.H2039","article-title":"Physiological time-series analysis using approximate entropy and sample entropy","volume":"278","author":"Richman","year":"2000","journal-title":"Am. J.-Physiol.-Heart Circ. Physiol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"76","DOI":"10.1016\/j.autneu.2013.02.013","article-title":"Investigating the mechanisms of cardiovascular and cerebrovascular regulation in orthostatic syncope through an information decomposition strategy","volume":"178","author":"Faes","year":"2013","journal-title":"Auton. Neurosci."},{"key":"ref_36","first-page":"9","article-title":"Sample estimate of the entropy of a random vector","volume":"23","author":"Kozachenko","year":"1987","journal-title":"Probl. Peredachi Inf."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"066138","DOI":"10.1103\/PhysRevE.69.066138","article-title":"Estimating mutual information","volume":"69","author":"Kraskov","year":"2004","journal-title":"Phys. Rev. E"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"346","DOI":"10.1016\/S0167-2789(00)00043-9","article-title":"Surrogate time series","volume":"142","author":"Schreiber","year":"2000","journal-title":"Phys. D Nonlinear Phenom."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"635","DOI":"10.1103\/PhysRevLett.77.635","article-title":"Improved surrogate data for nonlinearity tests","volume":"77","author":"Schreiber","year":"1996","journal-title":"Phys. Rev. Lett."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"123114","DOI":"10.1063\/1.5115506","article-title":"Comparison of methods for the assessment of nonlinearity in short-term heart rate variability under different physiopathological states","volume":"29","author":"Faes","year":"2019","journal-title":"Chaos Interdiscip. J. Nonlinear Sci."},{"key":"ref_41","unstructured":"(2022, March 29). The Government of the Republic of Serbia, Available online: https:\/\/www.srbija.gov.rs\/vest\/en\/151422\/measures-of-the-state-of-emergency.php."},{"key":"ref_42","unstructured":"(2022, May 03). The EMF RATEL Internet Portal. Available online: https:\/\/emf.ratel.rs\/results\/details\/eng\/9\/."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"14735","DOI":"10.1007\/s11356-020-08008-8","article-title":"Comparative analysis of EMF monitoring campaigns in the campus area of the University of Novi Sad","volume":"27","author":"Kljajic","year":"2020","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"101703","DOI":"10.1016\/j.compenvurbsys.2021.101703","article-title":"How did micro-mobility change in response to COVID-19 pandemic: A case study based on spatial-temporal-semantic analytics","volume":"90","author":"Li","year":"2021","journal-title":"Comput. Environ. Urban Syst."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Fonseca-Cabrera, A.S.S., Llopis-Castell\u00f3, D., P\u00e9rez-Zuriaga, A.M.M., Alonso-Troyano, C., and Garc\u00eda, A. (2021). Micromobility Users\u2019 Behaviour and Perceived Risk during Meeting Manoeuvres. Int. J. Environ. Res. Public Health, 18.","DOI":"10.3390\/ijerph182312465"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1080\/10630732.2014.942092","article-title":"Smart cities: Definitions, dimensions, performance, and initiatives","volume":"22","author":"Albino","year":"2015","journal-title":"J. Urban Technol."}],"container-title":["Entropy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1099-4300\/24\/5\/726\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:15:25Z","timestamp":1760138125000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1099-4300\/24\/5\/726"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,5,20]]},"references-count":46,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2022,5]]}},"alternative-id":["e24050726"],"URL":"https:\/\/doi.org\/10.3390\/e24050726","relation":{},"ISSN":["1099-4300"],"issn-type":[{"type":"electronic","value":"1099-4300"}],"subject":[],"published":{"date-parts":[[2022,5,20]]}}}