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1.
This study is aimed to clarify whether effect of low-level microwave radiation on human brain differs at different modulation
frequencies. Resting EEG recordings were done on different groups of healthy volunteers. The 450 MHz microwave radiation modulated
at 40 and 70 Hz (15 subjects) and 217 and 1,000 Hz (19 subjects) frequencies was applied. The results of our previous study
at 7, 14 and 21 Hz modulation were included into analysis. Ten cycles of the exposure (1 min off and 1 min on) at each fixed
modulation frequencies were applied. The field power density at the scalp was always 0.16 mW/cm2. Our results showed that microwave exposure increased the EEG energy at EEG frequencies lower or close to the modulation
frequency. No effect was detected at EEG frequencies higher than the modulation frequency. Statistically significant changes
were caused by exposure in the EEG alpha and beta frequency bands; no significant effect was detected in the theta band. Our
results suggest that telecommunication devices with complex spectrum of modulation frequencies like mobile phone can affect
all human EEG frequency bands. 相似文献
2.
Maie Bachmann Maksim Säkki Jaan Kalda Jaanus Lass Viiu Tuulik Hiie Hinrikus 《The Environmentalist》2005,25(2-4):165-171
Summary This study focuses on discrimination of changes, produced by low-level microwave exposure in intensity and time variability
of the human EEG at rest. The power spectral density (PSD) method and nonlinear scaling analysis of the length distribution
of low variability periods (LDLVP) were selected for analysis of the EEG signal. During the study, 19 healthy volunteers were
exposed to a microwave (450 MHz) of 217 Hz frequency on-off modulation. The field power density at the scalp was 0.16 mW/cm2. The experimental protocol consisted of ten cycles of repetitive microwave exposure. Signals from frontal, temporal, parietal
and occipital EEG channels on EEG theta, alpha and beta rhythms were analysed. Exposure to microwave causes average increase
of EEG activity. LDLVP analysis discriminated significant effect in time variability for 2 subjects (11%). PSD method detected
significant changes in intensity for 4 subjects (21%). The effect of low-level microwave exposure is stronger on EEG beta
rhythm in temporal and parietal regions of the human brain. 相似文献
3.
Maie Bachmann Ruth Tomson Jaan Kalda Maksim Säkki Jaanus Lass Viiu Tuulik Hiie Hinrikus 《The Environmentalist》2007,27(4):511-517
This study was aimed to investigate the changes in the human electroencephalographic (EEG) signal caused by modulated low-level
microwaves. The 450 MHz microwave exposure modulated at 40 Hz and 70 Hz frequencies was applied to a group of 15 volunteers.
The field power density at the scalp was 0.16 mW/cm2. Ten cycles of the exposure (1 min on and 1 min off) at both modulation frequencies were applied. Analysis of the EEG signal
was performed using three different methods: nonlinear method of scaling analysis for length distribution of low variability
periods (LDLVP), relative changes in EEG energy (S-parameter) and beta ratio (H-parameter). The analysis revealed significant changes caused by microwave for the whole group (H-parameter method). The exposure caused increase of the EEG beta power (S-parameter method). Statistically significant changes in EEG were detected for four subjects (26.7%) at 40 Hz modulation frequency
(LDLVP method). 相似文献
4.
Anna Suhhova Maie Bachmann Jaanus Lass Deniss Karai Hiie Hinrikus 《The Environmentalist》2009,29(2):210-214
This study is aimed to investigation of the effect of modulated 450 MHz microwave radiation on the EEG inter-hemispheric asymmetry.
Ten cycles of the microwave exposure (1 min off and 1 min on) at fixed modulation frequency were applied on two groups of
healthy volunteers. The first group of 13 subjects was exposed to microwave radiation modulated at 14 Hz and the second group
of 15 subjects at 40 Hz frequency. The peak specific absorption rate (SAR) average over 1 g was 0.303 W/kg. Differences in
SAR between hemispheres were up to 20 dB. Rod antenna was located from the left side of the head. Differences of relative
changes in EEG energy between symmetric channels FP1–FP2, T3–T4, P3–P4 and O1–O2 in exposed and sham conditions were analysed.
The results showed increase in EEG energy from the left side caused by microwave exposure. Statistical analysis done for the
whole group of subjects didn’t reveal significant differences in inter-hemispheres asymmetry between exposed and sham conditions.
However, statistical analysis performed for individual subjects detected significant differences in asymmetry caused by exposure
for 15–35% of individuals. 相似文献
5.
N. M. Salem 《The Environmentalist》2005,25(2-4):241-246
Summary The thermal effect due to electromagnetic absorption by human tissues is investigated at different frequencies ranging from
101–1016 Hz. Special emphasis is being considered in the microwave band used in wireless communications of the mobile industry. The
present work examines basically the thermal effect that arises as the duration of exposure to the electromagnetic radiation
and its dosage is increased. Using a computer simulation, a semi-classical model is adopted, were the photon-phonon interaction
is mediated by a homogenous sample of identical elements, which are naturally in harmonic modes of vibration. The phonon lifetime
is also included in this work. These thermal effects decrease with frequency in conformity with experimental results. This
model is then extrapolated to the individual cells of a human tissue and the possible rise in temperature is estimated. 相似文献
6.
Maie Bachmann Hiie Hinrikus Kaire Aadamsoo Ülle Võhma Jaanus Lass Jekaterina Rubljova Anna Suhhova Viiu Tuulik 《The Environmentalist》2007,27(4):505-510
This study was aimed to evaluate differences in the effect of microwave exposure on patients with depressive disorder and
healthy subjects. Our experiments were carried out on a group of depressive patients (women, 18 subjects) and comparison group
of healthy volunteers (women, 18 subjects) exposed during 30 min to 450 MHz microwave radiation modulated at 1,000 Hz frequency.
The field power density at the scalp was 0.9 mW/cm2. As a subjective criteria of microwave effect, the Brief Affect Scale (BAS) and Visual Analogue Scale (VAS) before and after
each exposure procedure were used. The analysis of EEG was performed and ratio of the EEG beta and theta power was selected
as a measure for evaluation of the microwave effect. The BAS and VAS revealed rather improvement in subjective mood score
after exposure for majority of depressive subjects (11) and no changes for others (7). The EEG analysis detected differences
between calculated parameters for exposed and sham recordings in depression as well as healthy group. Statistically significant
changes were introduced by microwave for five patients with depressive disorder and for one healthy subject. The rate of subjects
affected by microwave in depression group (28%) was five times higher compared to that rate in healthy group (5.6%). 相似文献
7.
Eleni Nanou Vassilis Tsiafakis E. Kapareliotis Charalabos Papageorgiou Andreas Rabavilas Christos Capsalis 《The Environmentalist》2005,25(2-4):173-179
Summary The effects of electromagnetic fields (EMF) emitted by cellular phones on human electroencephalogram (EEG) were studied during
an auditory memory task. The experimental method and the experimental setup are introduced as a credible measurement method
of EEG. 19 normal subjects (10 women and 9 men) performed the memory task both with and without exposure to a 900 MHz signal,
emitted by a dipole antenna placed near the subjects' head. The energy of the EEG signals was calculated at the time domain.
A Fourier transform of the EEG signals was done and the EEG energy was also calculated at the frequency domain. As the Parseval's
theorem anticipates the energies were identical. The EEG energy was found concentrated at the four basic bands (α (8–13 Hz),
β(14–30 Hz), δ (0–4 Hz) and θ(5–7 Hz)). The primary concern of the present study was the gender related influence of EMF on
the spectral energy of EEG. The results show evidence of a strong gender—radiation interaction effect on the EEG energy and
on the peak amplitudes within each of the four rhythms. Without radiation the spectral power of males is greater than of females,
while under exposure the situation is reversed. Under the influence of EMF the spectral power of the males EEG is decreased
while that of the females is increased. In conclusion both the baseline EEG and the changes effected to the EEG power spectrum
under the influence of EMF seem to be gender dependent. 相似文献
8.
Hiie Hinrikus Ruth Tomson Jaanus Lass Deniss Karai Jaak Kalda Viiu Tuulik 《The Environmentalist》2005,25(2-4):157-163
Summary This study is aimed to investigate dependence of nerve pulse conduction velocity on low-level microwave exposure. The changes
in fiber membrane permeability or myelin sheath, caused by microwave, should affect nerve pulse conduction velocity. Experimental
investigation was carried out for nerve pulse conduction velocity with and without applied microwave field and different orientations
of its polarization to the nerve fiber. Microwave radiation of 450 MHz was applied polarized perpendicular or parallel to
the nerve fiber. The measured field power density at the skin was 0.87 mW/cm2. Special program was developed for calculation of the nerve pulse conduction velocity in LabView environment. The right nervus
medianus motor nerve fibers of 35 young subjects were under the study. The experimental protocol included ten measurements
in every cycle of five different exposure conditions. No changes in average values of the conduction velocities discovered
in different exposure conditions. Theoretical calculations based on Hodgkin-Huxley model confirm only a weak possible effect.
The results showed that low-level microwave radiation did not cause statistically significant change in nerve pulse conduction
velocity in human motor nerve fiber. 相似文献
9.
Martino Grandolfo 《The Environmentalist》2009,29(2):109-117
Over the last years, a wide debate has developed on the possible health effects of exposure to electromagnetic fields. In-depth
research activity was therefore developed by the international scientific community aimed at evaluating the risk associated
with exposure to this type of radiation. At the same time, various international institutions began to issue recommendations
on exposure limits valid for workers and for the population in the frequency range up to 300 GHz. Most of the recently revised
safety standards worldwide are set in terms of internal rates of electromagnetic energy deposition (Specific Absorption Rate)
at radiofrequency and microwave frequencies, and of induced electric fields or current densities at lower frequencies up to
10 MHz. At the international level, the most authoritative guidelines have been developed by the International Commission
on Non-Ionizing Radiation Protection (ICNIRP); another internationally well recognized standard is that developed by the Institute
of Electrical and Electronics Engineers (IEEE) in the USA, adopting the same basic approach of ICNIRP, although with some
differences in numerical values.
This article is mainly focused on the analysis of different approaches for the protection against electromagnetic fields,
and on the rationale of most relevant standards. 相似文献
10.
11.
在高低温低气压试验中,由于空气稀薄,其温度均匀性试验已经无法用空气对流来实现了,只能通过的辐射和传导来实现和达到试验温度的均匀。在这种试验状况下,往往试验所得的温度、湿度的均匀性偏差很大。要实现较好的温度均匀性十分困难。我们将高真空领域中的热沉技术即辐射换热方式,运用到高(低)温低气压试验箱中,通过多个几何平面的辐射和传导,达到较为理想的试验参数。 相似文献
12.
G. Duranti A. Rossi N. Rosato G. Fazio G. Sacerdoti P. Rossi R. Falsaperla V. Cannelli R. Supino 《The Environmentalist》2005,25(2-4):113-119
Summary The biological effects of electromagnetic radiation at ultra high frequency on human keratinocytes were investigated. HaCaT
cell system, a spontaneously immortalized human keratinocytes cell line, was chosen as model since skin is usually exposed
to electromagnetic radiation at considered frequency more than inner tissues. HaCaT cells were exposed to a pure sinusoidal
field at a frequency of 900 MHz (average SAR levels ranging from 0.04 to 0.08 W/kg) in plane wave condition inside a GTEM
chamber for time intervals of 18 hours at a controlled temperature of 37∘C. Growth curves were obtained for exposed and control cells, and a reduction in the number of exposed cells in comparison
to unexposed ones was found; however the number of dead cells was not significantly different in exposed and unexposed samples.
In order to investigate whether the reduction in cell proliferation of exposed cells was due to the activation of a differentiative
process, the expression of two hallmarks of differentiation was examined. Both keratin 1 and involucrin expression was increased
in exposed in comparison to unexposed cells. These results suggest that this protocol of exposure to 900 MHz electromagnetic
field can trigger a differentiation program in HaCaT cells. 相似文献
13.
The effect of environmental conditions on the ability of a constructed wetland to disinfect municipal wastewaters 总被引:2,自引:0,他引:2
Zdragas A Zalidis GC Takavakoglou V Katsavouni S Anastasiadis ET Eskridge K Panoras A 《Environmental management》2002,29(4):510-515
Constructed wetlands are widely used all over the world for the treatment of municipal wastewaters, which are characterized
by high concentrations of pathogens. The objectives of this study were (1) to study the effect of solar radiation and temperature
on the ability of a constructed wetland to reduce the concentration of total coliforms (TC), and (2) to evaluate the relationship
between the presence of Salmonella spp. in the outflow and the concentration of TC. The results of this study showed that under Mediterranean environmental conditions,
the percentage reduction in coliforms was lower during winter compared to all other seasons. Maximum removal of coliforms
was achieved under conditions of high solar radiation and temperature. In addition, solar radiation was found to play a greater
role in coliform die-off at low temperatures than at high temperatures. Finally, it was found that the probability of Salmonella spp. appearance in the outflow of the wetland was related to the concentration of TC. The increase in coliform bacteria in the
effluents also increased the chances of Salmonella appearance. The risk of Salmonella spp. appearance in the outflow is minimized when the concentration of TC is below 102/100 mL. 相似文献
14.
The response of forest understory vegetation to trampling applied at different temporal and spatial scales was determined
in a cliff-edge forest in Ontario, Canada. Three frequencies (0, 50, 500 passes per year) of short-term trampling (one year)
were applied to plots previously undisturbed. Existing trails that had received three frequencies (approx. 100, 500, 25,000
passes per year) of long-term trampling (18 years) were also studied. Community composition, species richness, and individual
species frequency were recorded in plots within 4 m and (or) 1 m of the patch centerline. The quantitative and qualitative
form of plant response to increased trampling was compared for short-term and long-term treatments, both within 4 m and within
1 m of the path centerline, to judge the consistency of trampling effects at different temporal and spatial scales.
As trampling frequency increased, community composition changed progressively, but consistently, in plots both within 4 m
and 1 m of the path centerline. Species richness was less affected by trampling and only decreased within 1 m of the path
centerline at the highest level of trampling (25,000 passes per season for 18 years). Effects of trampling on individual species
frequency were much less consistent at different temporal and spatial scales of trampling. The scale-dependence results suggest
that field workers and resource managers both should try explicitly to include and define multiple scale components when trying
to ascertain the response of vegetation to human disturbance factors. 相似文献
15.
Summary The major objective of the design of safe crowded transmitting antenna sites is not only to determine a safe zone around each
individual antenna; rather, to establish safety areas at the antenna site itself, as well as, at the neighboring areas. The
requirement is to ascertain the safety regions by considering the following parameters at each Test Point (TP) (or area segment):
the contribution of N co-located radiating antennas to the total radiation incident at the TP, the radiation pattern of each antenna, the near/far
field region of each antenna, and most importantly, the different Permissible Exposure Limits (PELs) associated with each
operating frequency at the antenna site. Implementation of all the above-mentioned aspects in a suitable computer requires
resources that only expert knowledgeable organizations possess. The graphically aided tool presented in this paper facilitates
the calculation of a “safety zone” for RADHAZ around a crowded antenna site from the knowledge of the “safety ranges” which
correspond to the individual transmitting antennas comprising it. 相似文献
16.
17.
Y. R. Mikayelyan N. S. Baghdasaryan A. K. Nikoghosyan S. V. Barseghyan S. N. Ayrapetyan 《The Environmentalist》2012,32(2):179-187
The effects of extremely low-frequency electromagnetic field (ELF EMF) and ELF-modulated millimeter waves (MMW) on physicochemical
properties of physiological solution (PS) at different environmental medium were studied. The existence of frequency “windows”
at 4 Hz and 8 Hz frequencies of ELF EMF and ELF-modulated MMW which have different effects on heat fusion period (HFP), hydrogen
peroxide (H2O2) formation and oxygen (O2) content of water solution and different dependency on temperature, background radiation (BGR) and illumination was shown.
The obtained data allow us to suggest that cell bathing medium serving as a target through which the biological effects of
ELF EMF and ELF-modulated MMW on cells are realized is extra sensitive to environmental factors. Therefore, the variability
of experimental data on EMF biological effects, obtained in different laboratories can be explained by different environmental
conditions of experiments, which very often are not considered adequately. 相似文献
18.
19.
Saito L Miller WW Johnson DW Qualls RG Provencher L Carroll E Szameitat P 《Journal of environmental quality》2007,36(1):91-100
This study tested the hypothesis that stable C and N isotope values in surface soil and litter would be increased by fire due to volatilization of lighter isotopes. The hypothesis was tested by: (1) performing experimental laboratory burns of organic and mineral soil materials from a watershed at combinations of temperature ranging 100 to 600 degrees C and duration ranging from 1 to 60 min; (2) testing field samples of upland soils before, shortly after, and 1 yr following a wildfire in the same watershed; and (3) testing field soil samples from a down-gradient ash/sediment depositional area in a riparian zone following a runoff event after the wildfire. Muffle furnace results indicated the most effective temperature range for using stable isotopes for tracing fire impacts is 200 to 400 degrees C because lower burn temperatures may not produce strong isotopic shifts, and at temperatures>or=600 degrees C, N and C content of residual material is too low. Analyses of field soil samples were inconclusive: there was a slightly significant effect of the wildfire on delta15N values in upland watershed analyses 1 yr postburn, while riparian zone analyses results indicated that delta13C values significantly decreased approximately 0.71 per thousand over a 9 mo post-fire period (p=0.015), and ash/sediment layer delta13C values were approximately 0.65 per thousand higher than those in the A horizon. The lack of field confirmation may have been due to overall wildfire burn temperatures being <200 degrees C and/or microbial recovery and vegetative growth in the field. Thus, the muffle furnace experiment supported the hypothesis, but it is as yet unconfirmed by actual wildfire field data. 相似文献