Lars Ole Fichte

In recent decades, the widespread use of mobile phones and wireless technologies has led to a significant increase in radiofrequency electromagnetic fields (RF-EMFs), raising concerns about continuous RF-EMF exposure among the general population. Recent research indicates that real-life RF signals are more biologically active than controlled laboratory signals with a low variability, suggesting that living organisms can adapt to EMF exposure when the pattern has a low variability. However, using real-life sources with unpredictable variation signals in biological experiments contradicts the principle of experiment controllability. This paper aims to investigate the nature of signals generated by current sources of ambient EMFs in terms of stationarity, with the goal of replicating them in biological experiments to study the effects of EMF exposure. Employing a range of statistical methodologies, starting with descriptive statistical analysis and progressing to the advanced APDP and APTF methods, an examination is conducted on a collection of Wi-Fi signal recordings across various operating modes, with particular attention given to video streaming. The chosen datasets are scrutinized with respect to their adherence to a Gaussian distribution and the concept of stationarity. The results indicate that the observed Wi-Fi signals lack stationarity in both the time and frequency domains. However, based on the analytical findings, it is possible to generate signals in frequency that authentically replicate Wi-Fi signals, accounting for nonstationarity considerations.

Radiofrequency electromagnetic fields (RF-EMF) are a basic requirement of modern wireless communication technology. Statutory thresholds of RF-EMF are established to limit relevant additional heat supply in human tissue. Nevertheless, to date, questions concerning nonthermal biological effects have yet to be fully addressed. New versions of microarrays (8 x 60K v2) provide a higher resolution of whole genome gene expression to display adaptive processes in cells after irradiation. In this ex vivo/in vitro study, we irradiated peripheral blood cells from five donors with a continuous wave of 900 MHz RF-EMF for 0, 30, 60 and 90 min. Gene expression changes (P <= 0.05 and >= twofold differences above or below the room temperature control exposed samples) were evaluated with microarray analysis. The results were compared with data from room temperature + 2 degrees C samples. Verification of microarray results was performed using bioinformatic analyses and qRT-PCR. We registered a lack of an EMF-specific gene expression response after applying the false discovery rate adjustment (FDR), using a high-stringency approach. Low-stringency analysis revealed 483 statistically significant deregulated transcripts in all RF-EMF groups relative to the room temperature exposed samples without an association with their corresponding room temperature + 2 degrees C controls. Nevertheless, these transcripts must be regarded as statistical artefacts due to the absence of a targeted biological response, including enrichment and network analyses administered to microarray expressed gene subset profiles. Correspondingly, 14 most promising candidate transcripts examined by qRT-PCR displayed an absence of correlation with respect to the microarray results. In conclusion, these findings indicate that 900 MHz EMF exposure establishing an average specific absorption rate of 9.3 W/kg to whole blood cells is insufficient to induce nonthermal effects in gene expression during shorttime exposure up to 90 min. (C) 2018 by Radiation Research Society

Various solutions to plane low frequency eddy current problems can be found in the literature, nearly all of which employ numerical methods like finite element or finite difference methods, and solve the problem on a mesh by evaluating the equations governing fields or potentials at discrete observation points. Yet, for the kind of problem under investigation in this paper, there is an approach which involves numerical approximations only for calculating the integrals involved (in those cases that can not be treated analytically) and for solving the resulting system of linear equations. This hybrid analytical-numerical approach combines a BIE formulation and a separation of the differential equation of an appropriate vector potential and can be useful to evaluate quality, residuals and covergence of numerical solutions. Since the in-depth discussion of the single terms in the formulation is beyond the scope of a conference paper, we will focus on the governing equations, the kernel functions of the BIE and on appropriate series representations expressions that faciliate the calculation.

The purpose of this work is to establish a numerical framework capable of generating simulation data with the same statistical properties as the represented electrical reverberation chamber (ERC). While an ERC whose resonating volume is geometrically varied produces randomly distributed fields, a numerical simulation is a deterministic system. However, the statistical distributions of electrical fields may nevertheless correspond. Such a simulation would allow for predicting if a certain design of an ERC is suited for a particular purpose. The numerically gained data are compared with empirical results for small reverberation chambers. To characterize the statistical properties of the electrical fields obtained either by experiments or by simulation, adequate tests are applied. The simulation tool shall be applied to validate and optimize new concepts of reverberation chambers, e.g., for biological experiments, microwave-spectroscopy or with new mode stirring devices.

The purpose of this work is to develop a knowledge base which allows for the assessment of the influence of individual construction parameters on a mode stirred chamber's performance in its particular area of application. With this knowledge, it would be possible to adapt a chamber for a particular purpose, e.g. to use the chamber for electromagnetic compatibility test procedures or for power spectroscopic measurements. The scattering parameters as well as the field strength and the distribution of the electric field are employed to quantify the influencing construction parameters of the chamber. In addition, a concept for a 3D positioning system is presented which can be used to accurately measure the electric field in the chamber. This is necessary in order to be able to make statistical statements about the electric field distribution.

High Altitude Nuclear Electromagnetic Pulses (HEMP) are among most extreme external signals that can interfere with an electric device. To ensure the survival of vital components even in case of a HEMP event, several procedures have been designed to test DUTs in a lab environment. As a consequence, field tests with HEMP simulators are mandatory. A valid estimation of the level which will cause a failure of the DUT due to the external HEMP (either generated artificially or by a real life HEMP event) will allow engineers to fix better field levels for HEMP susceptibility tests and to avoid overtesting. This paper will apply binary regression models such as as logit or probit on the results of HEMP tests from the literature and estimate an more applicable test level as a first step. Concluding, additional possibilities of the regression models are discussed.