Viiu Tuulik

Effect of 7, 14 and 21 Hz modulated 450 MHz microwave radiation on human electroencephalographic rhythms

Purpose: The aim of this study was to evaluate the effect of microwaves modulated at different frequencies on human electroencephalographic (EEG) rhythms. Materials and methods: Thirteen healthy volunteers were exposed to microwaves (450 MHz) pulse-modulated at frequencies of 7, 14 and 21 Hz. The field power density at the scalp was 0.16 mW/cm2. Our experimental protocol consisted of two five-cycle (1 min on and 1 min off) series of exposures at fixed modulation frequencies. A relative change in the EEG power with and without exposure was used as a quantitative measure. EEG frequencies recorded in the theta (4 – 6.8 Hz), alpha (8 – 13 Hz), beta1 (15 – 20 Hz), and beta2 (22 – 38 Hz) bands were analyzed. Results: Modulated microwaves caused an increase in the average EEG alpha (17%) and beta (7%) power but the theta rhythm remained unaffected. Increases in the EEG alpha and beta power were statistically significant during the first half-period of the exposure interval (30 s) at the modulation frequencies of 14 and 21 Hz. Differences were found in individual sensitivity to exposure. Increases in the EEG beta power appeared statistically significant in the case of four subjects. Conclusions: Our findings suggest that the effect of the 450 MHz microwave radiation modulated at 7, 14 and 21 Hz varies depending on the modulation frequency. The microwave exposure modulated at 14 and 21 Hz enhanced the EEG power in the alpha and beta frequency bands, whereas no enhancement occurred during exposure to the modulation frequency of 7 Hz.

Effects of 7 Hz-modulated 450 MHz electromagnetic radiation on human performance in visual memory tasks

Purpose : The aim was to examine low-level 7 Hz-modulated 450 MHz radiation effects on human performance in visually presented neuropsychological tasks associated with attention and short-term memory. Materials and methods : A homogeneous group of 100 subjects (37 female, 63 male) were randomly assigned to either the exposed (10-20 min, 0.158mW cm -2) or the sham-exposed group. A battery of three different tests measured attention and shortterm memory. Task 1 involved alternately selecting black digits from 1 to 25 in ascending order and white digits from 24 to 1 in descending order. The time spent on the task and the number of errors were recorded and analysed. Task 2 involved viewing a picture of 12 objects during 3 s, followed by a list of 24 words. The subject was required to select words representing previously presented objects. In task 3, an array of letters in 10 rows (60 in each row) was presented, and the subject was required to identify all examples of a particular two-letter combination. Results : The results of tasks 1 and 3 showed a significant increase in variances of errors (p <0.05) in the exposed versus the shamexposed group. The results of task 2 indicated a significant decrease in errors (p <0.05) in the exposed group. Conclusions : The data provide additional evidence that acute lowlevel exposure to microwaves modulated at 7 Hz can affect cognitive processes such as attention and short-term memory.

Effect of low frequency modulated microwave exposure on human EEG: individual sensitivity.

The aim of this study was to evaluate the effect of modulated microwave exposure on human EEG of individual subjects. The experiments were carried out on four different groups of healthy volunteers. The 450 MHz microwave radiation modulated at 7 Hz (first group, 19 subjects), 14 and 21 Hz (second group, 13 subjects), 40 and 70 Hz (third group, 15 subjects), 217 and 1000 Hz (fourth group, 19 subjects) frequencies was applied. The field power density at the scalp was 0.16 mW/cm(2). The calculated spatial peak SAR averaged over 1 g was 0.303 W/kg. Ten cycles of the exposure (1 min off and 1 min on) at fixed modulation frequencies were applied. All subjects completed the experimental protocols with exposure and sham. The exposed and sham-exposed subjects were randomly assigned. A computer also randomly assigned the succession of modulation frequencies. Our results showed that microwave exposure increased the EEG energy. Relative changes in the EEG beta1 power in P3-P4 channels were selected for evaluation of individual sensitivity. The rate of subjects significantly affected is similar in all groups except for the 1000 Hz group: in first group 3 subjects (16%) at 7 Hz modulation; in second group 4 subjects (31%) at 14 Hz modulation and 3 subjects (23%) at 21 Hz modulation; in third group 3 subjects (20%) at 40 Hz and 2 subjects (13%) at 70 Hz modulation; in fourth group 3 subjects (16%) at 217 Hz and 0 subjects at 1000 Hz modulation frequency.

Non-linear analysis of the electroencephalogram for detecting effects of low-level electromagnetic fields

The study compared traditional spectral analysis and a new scale-invariant method, the analysis of the length distribution of low-variability periods (LDLVPs), to distinguish between electro-encephalogram (EEG) signals with and without a weak stressor, a low-level modulated microwave field. During the experiment, 23 healthy volunteers were exposed to a microwave (450 MHz) of 7 Hz frequency on-off modulation. The field power density at the scalp was 0.16 mW cm−2. The experimental protocol consisted of ten cycles of repetitive microwave exposure. Signals from frontal EEG channels FP1 and FP2 were analysed. Smooth power spectrum and length distribution curves of low-variability periods, as well as probability distribution close to normal, confirmed that stationarity of the EEG signal during recordings was achieved. The quantitative measure of LDLVPs provided a significant detection of the effect of the stressor for the six subjects exposed to the microwave field but for none of the sham recordings. The spectral analysis revealed a significant result for one subject only. A significant effect of the exposure to the EEG signal was detected in 25% of subjects, with microwave exposure increasing EEG variability. The effect was not detectable by power spectral measures.

Integration of differences in EEG Analysis Reveals Changes in Human EEG Caused by Microwave

Three different methods in combination with integration of differences in signals were applied for EEG analysis to distinguish changes in EEG caused by microwave: S-parameter, power spectral density and length distribution of low variability periods. The experiments on the effect of modulated low-level microwaves on human EEG were carried out on four different groups of healthy volunteers exposed to 450 MHz microwave radiation modulated with 7 Hz, 14 Hz, 21 Hz, 40 Hz, 70 Hz, 217 or 1000 Hz frequencies. The field power density at the scalp was 0.16 mW/cm2. The EEG analysis performed for individuals with three different methods showed that statistically significant changes occur in the EEG rhythms energy and dynamics between 12% and 30% of subjects

Microwave radiation has modulation frequency dependent stimulating effect on human EEG rhythms

This study is focused on low-level modulated microwave field effects on human EEG theta, alpha and beta rhythms at different modulation frequencies. During the experiment 13 healthy volunteers were exposed to a microwave (450 MHz) with 7 Hz, 14 Hz and 21 Hz frequency on-off modulation. The field power density at the scalp was 0.16 mW/cm/sup 2/. The experimental protocol consisted of five cycles of the repetitive microwave stimulation at fixed modulation frequencies. Changes in the EEG rhythms energy became evident in the case of modulation frequencies higher than the EEG rhythms frequencies. The changes varied strongly from subject to subject. Microwave exposure caused statistically significant changes in the EEG theta rhythm energy and for occipital channels in the alpha rhythm energy.

Low-level microwave effects on EEG

The results of investigation of low-level modulated microwave effects on human EEG are presented. The theoretical estimation of the sensitivity of cells to microwave fields confirms that very low intensities of radiation would affect living systems. The microwave radiation effects on the vigilance level of the human brain have been studied by comparison with photic stimulation on a homogeneous group of young healthy volunteers. The study of EEG photic stimulation effects at 16 Hz frequency and microwave radiation stimulation effects at 450 MHz frequency modulated with 7 Hz, 16 Hz and 30 Hz frequency shows that the changes caused by these factors in the EEG alpha-wave spectrum have a similar character: depression of alpha-waves and recovering after a 10-20 second period. The microwave effects take place at 7 Hz modulation frequency only and the recovering period for these is longer than for photic stimulation.

Adaptation of Human Brain Bioelectrical Activity to Low-Level Microwave

The experiments of adaptation of the human brain bioelectrical activity were carried out on a group of 14 healthy volunteers exposed to 450 MHz microwave radiation modulated at 40 Hz frequencies. The field power density at the scalp was 0.16 mW/cm2. Results of the study indicate that adaptation effect of human brain to low-level microwave exposure is evident. The initial increase of EEG power was compensated and even overcompensated. The adaptation phenomena were obvious in EEG alpha and beta rhythms.

EEG Spectral Asymmetry Index Reveals Effect of Microwave Radiation

This study is aimed to test the EEG spectral asymmetry index (SASI) in different brain states. The SASI parameter was previously developed for depressive disorder. In this study it was assumed that microwave exposure can alter the brain state and the SASI could estimate the changes. For this, 15 healthy subjects were exposed to 450 MHz microwave radiation modulated at 40 Hz and 70 Hz frequencies. The field power density at the scalp was 0.16 mW/cm2. The analysis revealed significant rise in SASI value caused by 40 Hz modulated microwave for the whole group. Microwave modulated at 70 Hz also raised the SASI level, however the increase did not reach the level of significance. Despite the large increase in average SASI level, it still remained negative while in case of depressive disorder the SASI level was positive. Experimental results confirm that the EEG SASI detects changes in the brain state caused by different reasons.

Employee Performance, Working Time and Tiredness in Creative R&D Jobs: Employee Survey from Estonia

Optimal use of the intellectual resources of R&D employees is a significant success factor for achieving innovation and socio-economic development. Statutory and company level regulation of working time, including the durations and timing of a working day and a working week, remains a common feature in many countries, and these rules often apply, among others, to creative R&D employees. Our study seeks to investigate the relationships between the drivers and outcomes of creative R&D employees’ work performance with particular focus on working time arrangement and the related tiredness, workability, work satisfaction and creativity issues. Our survey covers a sample of 160 creative R&D employees in Estonia. This conference proceedings paper gives an overview of some aspects of the first phase of our survey, while the more detailed results will be published in separate papers. Our findings include that 79% of the surveyed employees would prefer to work under a different working schedule compared to the standard 5-day working week, and 81% would prefer to have a daily schedule with an irregular start and/or end time of the working day. Emotional tiredness, sleepiness, low salary and inefficient time use are seen as major obstacles to achieving creative work results.