Radiofrequency Electromagnetic Radiation Research Articles

Abstract 1646: Preclinical oxygen imager for cancer oxygenation studies

Abstract Oxygen is an important biomarker in cancer biology studies. Tumor hypoxia is one of the most important factors that regulate tumor growth, development, aggressiveness, metastasis and affects treatment outcome. Tumor hypoxia is spatially heterogeneous. Despite the clear importance of tumor oxygenation, most scientists studying tumor hypoxia or oxygen kinetics still rely on two-dimensional cell biology techniques. Most radiation resistance studies are performed in cell cultures or in vivo/in vitro systems where tumors are radiated in situ and tumor cells subsequently explanted, cultured, and studied for survival. Absence of reliable oxygen imaging instrument capable, with sufficient spatial and temporal resolution, of imaging hypoxia in tumor's volume is a challenge for the research field. We report the construction of the first commercial preclinical oxygen imager, JIVA-25, based on electron paramagnetic resonance oxygen imaging (EPROI). EPROI is a non-invasive oxygen mapping method with high precision and absolute accuracy (1). EPR detects unpaired electron spins subjected to the constant uniform magnetic field by manipulating them using radio-frequency electromagnetic radiation. EPROI uses an injectable non-toxic soluble contrast agent, trityl (OX063/OX063-D24) for obtaining oxygen maps in tumor models. EPROI was used recently for the first demonstration of oxygen guided radiation therapy in a mouse model of tumor (2). JIVA-25 is a compact 25 mT EPROI instrument suitable for in vitro and small animal in vivo oxygen mapping in tumor models of mice and rats. JIVA-25 provides pO2 maps with a high spatial resolution (up to 0.5 mm), high pO2 resolution (1-3 torr), and high temporal resolution (1-10 min). Currently, the instrument is being tested for its efficacy to provide tumor treatment in mouse model at two locations, Duke Cancer Institute and the University of Chicago. Further development to improve the spatial resolution using NCI developed single point imaging (SPI) is underway using NCI funded SBIR Phase II project. Overall, we expect that JIVA-25 will be a unique tool in helping scientists understand tumor oxygenation, perform efficient tumor treatment studies, and drug development. Acknowledgement: We acknowledge support from NIH/NCI R43CA224840, NIH/NCI R44CA224840, NSF 1819583, and JDRF 3-SRA-2020-883-M-B.

Use of radiofrequency electromagnetic radiation to remove biofilms from canvasses

A method based on the use of electromagnetic radiation (EMR) in the radiofrequency band was experimented to eliminate heterotrophic organisms from biofilms encrusting linen canvasses used for paintings. Artificial biofilms were used for exposure to EMR. Biofilms were grown on fragments of canvasses sampled from the backside of a painting. The fragments, after sterilization, were inoculated with several heterotrophic microorganisms previously isolated from other canvasses used for paintings and identified by molecular analyses as the bacteria Bacillus mycoides and Bacillus subtilis, and the microfungi Aspergillus versicolor, Cladosporium cladosporioides, Cladosporium oxysporum and Fusarium oxysporum. The newly formed biofilms resulted to contain the same microorganisms used for the inocula. They were exposed to EMR obtained by an amplitude-modulating radiofrequency sine wave with a train of rectangular pulses with 200 ns repetition time and 10% duty cycle. The exposure protocol consisted of three applications of two hours each, every other day. Denaturing gradient gel electrophoresis analyses carried out on the EMR-treated biofilms showed that all the microorganisms disappeared after the third application. The amplitude of the adopted EMR was not high enough to cause any significant increase in the temperature of the substrates. Therefore, the methodology showed to be non-invasive for the artefacts and its exposure levels not hazardous for operators and the environment compared to other techniques adopted in the field of conservation of cultural heritage. Among the latter techniques, the most common one is based on the use of biocides that, although effective, present problems in all the above-described areas.

Experimental study on broadband radiofrequency electromagnetic radiations near cellular base stations: a novel perspective of public health

The purpose of this study is to measure and document the maximum level of broadband radiofrequency electromagnetic radiations in the vicinity of cellular base stations. The measured broadband frequency range from 467.5 MHz to 3.5 GHz, which includes most cellular services, is considered. The power densities were found to vary from 40 µW m−2 to 34.12 mW m−2. The field measurements of 276 different sites distributed across various rural and urban areas regions in the Kingdom of Saudi Arabia were conducted, and the radiation levels were assessed. It is observed that the broadband radiation power densities were found to be higher in urban areas as compared to rural ones, whereas the maximum radiation point was found to be closer to the cellular base stations in the urban areas. The broadband radiation levels were to be compliant with the International Commission on Non-Ionizing Radiological Protection and US Federal Communication Committee standards for general public.

Effects of 2.1 GHz Electromagnetic Radiation on Locomotor Activity, Recognition Memory, and Anxiety-Related Behavior in Rats

The effects of short-term (2 h per day for 7 days) exposures to different doses of 2.1 GHz radiofrequency electromagnetic radiation (RF-EMR) on cognition and behavior of rats were examined. The animals were divided into three equal groups, sham-exposed group 1 and two RF groups irradiated with different doses, groups 2 and 3, respectively. To assess locomotor activity, recognition memory, and anxiety-related behavior, the open field (OF), novel object recognition (NOR), and marble burying (MB) tests were used, respectively. Overall results showed that both 45 and 65 V/m doses of 2.1 GHz RF-EMR did not lead to significant modifications of locomotor activity in the OF test. At the same time, higher doses (65 V/m) significantly (about two times) decreased the exploration time and number of touches for a novel object in the NOR test. In the MB test, both RF-EMR doses led to significant dose-dependent decreases in the number of buried marbles, which was indicative of lower levels of anxiety. Further studies are needed, regarding this particular type and level of radiation, for the development of methods to provide protection of the brain from harmful effects of RF-EMR exposure.

Machine learning-based identification of radiofrequency electromagnetic radiation (RF-EMR) effect on brain morphology: a preliminary study.

The brain of a human and other organisms is affected by the electromagnetic field (EMF) radiations, emanating from the cell phones and mobile towers. Prolonged exposure to EMF radiations may cause neurological changes in the brain, which in turn may bring chemical as well as morphological changes in the brain. Conventionally, the identification of EMF radiation effect on the brain is performed using cellular-level analysis. In the present work, an automatic image processing-based approach is used where geometric features extracted from the segmented brain region has been analyzed for identifying the effect of EMF radiation on the morphology of a brain, using drosophila as a specimen. Genetic algorithm-based evolutionary feature selection algorithm has been used to select an optimal set of geometrical features, which, when fed to the machine learning classifiers, result in their optimal performance. The best classification accuracy has been obtained with the neural network with an optimally selected subset of geometrical features. A statistical test has also been performed to prove that the increase in the performance of classifier post-feature selection is statistically significant. This machine learning-based study indicates that there exists discrimination between the microscopic brain images of the EMF-exposed drosophila and non-exposed drosophila. Graphical abstract Proposed Methodology for identification of radiofrequency electromagnetic radiation (RF-EMR) effect on the morphology of brain of Drosophila.

Investigating the impact of mobile range electromagnetic radiation on the medial prefrontal cortex of the rat during working memory

Research has been focused on the effects of radiofrequency electromagnetic radiation (RF-EMR) emitted from a mobile phone on general health, especially the nervous system.The purpose of this study was to investigate the impact of RF-EMR on the brain mechanism of rats by recording local field potentials (LFPs) signals during working memory (WM) task.Subjects were exposed to 900 MHz from a dipole antenna daily for three hours. Exposure was applied, first on a short term base (1 week) and then on a long term base (4 weeks). Behavioral parameters were measured weekly while rats performed T-maze tasks in two types of normal and delayed. LFPs signals were simultaneously recorded by implanted microelectrode arrays on the medial prefrontal cortex (mPFC) of rats.Results showed a significant increase (*p < 0.05) in the task completion time of exposed rats which vanished shortly after the end of short term RF-EMR exposure. Before exposure, during correctly performed delayed tasks, an increase (peak) in power changes of theta band (4−12 Hz) was observed. But during correctly performed normal tasks, an increase appeared only by applying RF-EMR exposure. The similarity in power changes pattern of theta band in both types of tasks was observed after long term exposure. Classification accuracy of LFPs in truly done normal and delayed tasks was compared in pre and post-exposure states. Initial classification accuracy was 84.2 % which decreased significantly (*P < 0.05) after exposure.These observations indicated that RF-EMR may cause unusual brain functioning which is temporary at least for short term exposure.

Numbrigal simulation of a thermodynamic process to decompose gas hydrate in a gas production well using, radiofrequency electromagnetic radiation

The formation of gas hydrate deposits on the inner surface of gas production equipment is a frequently occurring type of complication in gas production, leading to a significant decrease in the useful section of pipes and gas pipelines. The intensity of their formation can lead to a complete overlap of the lifting pipes and annular channels in the annulus in certain areas, which necessitates repair work to clean the wells of gas hydrates. Based on the analysis of methods for cleaning wells from gas hydrate deposits, it was revealed that in some cases one of the effective methods of preventing their formation and combating them is to use the energy of high-frequency and superhigh frequency electromagnetic fields. The article explores the processes of heating and decomposition of gas hydrate deposits in the wellbore. About 30% of the thermal energy released in the wellbore interacting with the electromagnetic field is consumed to heat the medium surrounding the well. The need for timely removal of the gas-water mixture formed in the annulus for the decomposition of gas hydrate along the entire length of the well is established.

Evaluation and Substantiation of the Necessity to Revise Guidelines for Measuring Electromagnetic Radiation of Cellular Base Stations

Introduction: Measurements of electromagnetic radiation of the radio frequency range are of great relevance due to the increasing number of transmitting radio facilities in the densely populated territories, constant cell site upgrades, and emerging communication standards. The paper presents a brief description of the biological effects of radio frequency electromagnetic radiation and shows basic mechanisms of the negative effect on the most vulnerable organs and systems. Our objective was to evaluate valid guidelines for measuring electromagnetic radiations of the radio frequency range in residential areas, in houses and public buildings. Materials and methods: We reviewed specific characteristics of cellular base and radio relay stations, compared and described electromagnetic radiation measuring devices. The provided recommendations for their selection were based on frequencies at which the communication equipment operates. We also analyzed the current guidelines with account for characteristics of transmitting radio equipment of cellular base stations and the applied measuring instruments. Results: The results of assessing established significant differences are discussed. The analysis of the requirements for measurements demonstrated significant discrepancies and contradictions between the valid documents. The evaluation results demonstrated impossibility of simultaneous measurements of electromagnetic radiation from cellular BS and RRS due to violations of requirements for measurement procedures. We concluded that, according to the current method documents, measurements of electromagnetic radiation from the fourth (4G) and fifth (5G) generation mobile communications systems were not possible. Conclusions: We revealed the necessity to revise the compared guidelines МUК 4.3.1167–02 and МUК 4.3.1677–03, to harmonize regulatory requirements for measurements, and to develop a single document guiding measurements of radio frequency electromagnetic radiation. Recommendations for taking measurements are provided.

Assessment of function, histopathological changes, and oxidative stress in liver tissue due to ionizing and non-ionizing radiations.

Background:Compared to past decades, humans are exposed to rapidly increasing levels of radiofrequency electromagnetic radiations (RF-EMF). Despite numerous studies, the biological effects of human exposure to different levels of RF-EMF are not fully understood yet. This study aimed to evaluate the bioeffects of exposure to "900/1800 MHz" and “2.4 GHz" RF-EMFs, and x-rays alone as well as their potential interactions, i.e. inducing simple additive, adaptive, or synergistic effects.Methods:120 Wistar rats were randomly divided into ten groups of 12 each. The rats were exposed to RF-EMF, 10 cGy, and 8 Gy x-rays, a combination of these exposures, or only sham-exposed. The levels of liver enzymes were determined in serum samples by an auto-analyzer. Moreover, the histopathological changes, and the levels of malondialdehyde (MDA), nitric oxide, ferric reducing antioxidant power, total thiols, and protein carbonyl (PCO) were measured.Results:Among the markers of liver function, gamma-glutamyltransferase was not associated with irradiation but, aspartate transaminase, alanine transaminase, and alkaline phosphatase showed some levels of association. MDA and PCO levels after 8 Gy irradiation increased, but pre-exposure to RF-EMF could modulate their changes. At the cellular level, the frequency of lobular inflammation was associated with the type of intervention.Conclusion:The exposure to both ionizing and non-ionizing radiations could alter some liver function tests. A short term pre-exposure to RF-EMF before exposure to an 8 Gy challenging dose of x-rays caused the alterations in oxidative stress markers and liver function tests, which indicate that oxidative stress is possibly involved in the adaptive response.

Health Hazards Associated with Electric and Magnetic Field Intensities around Mobile Base Stations in Katsina State, Nigeria

This work was carried out to assess the health hazards associated with exposure to radiofrequency electromagnetic fields from mobile base stations (MBS) within Katsina, Nigeria. Seventy seven MBS were identified through reconnaissance survey. Received radiated power was measured at a distance of 0, 20, 40, 60 and 80m from the MBS using a handheld B and K precision spectrum analyser. Electric and magnetic field intensities (E and H) were calculated. E (mV/m) and H (μA/m) had average values of; 21.03 and 55.78 for MTN; 9.41 and 24.96 for GLO; 2.33 and 6.18, for Etisalat; 18.32 and 48.62 for Airtel. Our results indicated that the general public exposure from radiofrequency electromagnetic radiation from all the considered mobile base stations is within the acceptable threshold of 61 V/m for Electric field intensity and 0.16A/m for Magnetic field intensity.&#x0D; Keywords: Mobile base stations, Radiation, Katsina, Health hazard, Electric field, Magnetic field

1800MHz Radiofrequency electromagnetic radiation: Does it affect heat shock genes expression levels in the rat brain?

The brain could recognizethe cell phone radiation as environmental stress and may alter stress-related gene expression levels. Heat shock proteins (HSP) are a family of proteins that are produced by cells in response to the exposure of stressful conditions. We investigated whether exposure to 1800MHz Radiofrequency Electromagnetic Radiation (RF-EMR) recognize the expression levels of some HSPs (Cryaa, Crybb, Hsp20, Hsp25, Hsp70) in mature rat’s brain tissue. The experimental group was exposed to 1.800MHz RF-EMR in restrainer for eight weeks with 2 h/day. The specific absorption rate (SAR) was 0.06 W/kg. The sham group was kept in restrainer but not exposed to radiation. The Control group was kept under their condition. Whole brain was homogenized.ViA7 Real-Time-PCR software was used to measure CT values of the genes and ΔΔCT values were also calculated. Cryaa (p=0.02), Crybb (p=0.01), and Hsp20 (p

Investigation of the Effects of Radio Frequency Water Treatment on Some Characteristics of Growth in Pepper (&amp;lt;i&amp;gt;Capsicum annuum&amp;lt;/i&amp;gt;) Plants

The aim of the present study was to investigate the effect of electromagnetic radio frequency treatment of water on the growth of pepper (Capsicum annuum) plants. For this experiment, one hundred one-week old plants were divided into two groups. The first group of plants was watered with water subjected to radio frequency electromagnetic radiation from an internet router for one hour a day, while the other group was watered with tap water (control). The overall results showed changes of growth characters of plant watered with electromagnetic water. The length of pepper plants is significantly affected by the treated water, where the length of shoot was lower in plants grown under the effect of treated water (22.43 ± 7.17 cm) than those grown without treated water (28.11 ± 8.57 cm). The results revealed that the stem diameter of control plants (1.74 ± 0.39 cm) was significantly higher than that of the treated plants (1.66 ± 0.35 cm). In addition, the root length was lower in plants grown under the effect of treated water than those grown without treated water. Pepper plants watered with electromagnetic treated water exhibited marked decreases in health index, fresh and dry weight, relative water content, number of flowers and fruits/plant as well as number of seeds/fruit. In addition, the current experiment showed a significant decrease in the number of leaves, branch and flower per plant when watered with electromagnetic treated water. The results revealed that the first flowering time for plants in treated group was remarkably decelerated when compared to other plants in control group.

Exposure of Radiofrequency Electromagnetic Radiation on Biochemical and Pathological Alterations

In the era of globalization, too much dependency on mobile phones is a cause of concern. The present study was designed to evaluate the risk assessment of microwave radiation (MWR) at 1800 MHz frequency and specific absorption rate 0.433 (W/kg) on male Wistar rats. Animals were divided into two groups: the first group is the control group, and the second group was exposed to 1800 MHz radiation for 90 days at 4 h/5 days/week in a month. Chronic exposure of MWR may alter GSH homeostasis due to alteration in various GSH cycle regulating enzymes such as GR, GPx, GST, and G6PDH which showed an imbalance in GSH content and causes an increase in the oxidative stress and release of inflammatory cytokines. A remarkable increase in the DNA damage was seen due to disorganization and pyknosis of neurons in exposed animal's brain when compared with the control group (P ≤ 0.05). There was also a significant decline in AChE level. The study concludes that MWR may cause neurochemical and pathophysiological damage by initiating the inflammatory process in various brain regions, especially in hippocampus and cerebral cortex. These effects are further associated with a remarkable elevation in the genotoxicity of neurons with reference to the control group.

Moderate exercise training reduced the harmful effects of electromagnetic radiation emitted from a cell phone on hematological parameters in male Wistar rats

Cell phones emit radiofrequency electromagnetic radiation (RF-EMR) that negatively affects the hematological blood profile. Therefore, the present study aimed to investigate whether exercise training can exert any protective impacts on hematological parameters in male Wistar rats. Twenty-four male Wistar rats (10 weeks old) were randomly assigned to e exposure to RF-EMR (RF-EMR) group, exercise group RF-EMR plus exercise (RF-EMR + Exercise) group, and control group. The rats in the exposure to RF-EMR groups (RF-EMR and RF-EMR + exercise) were exposed to RF-EMR 3 h/day for 28 days. The rats in the exercise groups (exercise and RF-EMR + exercise) were administered to moderate exercise training 6 days a week for 28 days. After 28 days, animals were sacrificed 24 h following the completion of the experiment, and hematological parameters, including complete blood count, were assessed. Exposure to RF-EMR induced a significant decrease in RBC, HGB, HCT, MCV, MCH, and MCHC, and an increase in PLT and WBC in compared with the control group (p < 0.05). However, most of the hematological parameters of the RF-EMR + exercise group were similar to the control group (except for PLT) that showed the inhibitory effect of exercise training against the harmful effects of cell phone radiation. 28 day moderate exercise training is beneficial to attenuate the harmful effects of RF-EMR emitted from the cell phone.

Public Engagement with Science in Everyday Life: Perceptions of Wi-Fi Radiation Risks in Schools

Wi-Fi radiation is a type of radio frequency electromagnetic radiation (RF-EMR) that refers to the transfer of energy by radio waves. Nowadays, exposure to RF radiation is widespread including wireless internet connection (Wi-Fi) routers and cell phones. The proliferation of devices emitting RF radiation has entailed some public and media-generated controversy, although scientific evidence has not pointed to the existence of risk. Using the theoretical perspectives of science literacy, public engagement with science, and science media literacy, this work examines public engagement with science-related media reports in a context involving risk. A qualitative design was followed to address multiple viewpoints including an analysis of an authentic primetime TV program concerning the risks of Wi-Fi, its messages, and frames, solicited a public response to the coverage via interviews and decision-making simulation (n = 20), and unsolicited public response based on social media discussions (n = 315 comments). Our findings suggest that a lack of relevant scientific knowledge does not seem to be related to participants’ general scientific literacy among people with higher education. Moreover, interviewees did not place much emphasis on having adequate knowledge in making their decision. These findings emphasize that we need to expand our understanding of the different ways that make scientific knowledge relevant when making decisions on scientific issues that relate directly to everyday life.

Long-term exposure to 4G smartphone radiofrequency electromagnetic radiation diminished male reproductive potential by directly disrupting Spock3–MMP2-BTB axis in the testes of adult rats

The correlation between long-term exposure to SRF-EMR and the decline in male fertility is gradually receiving increasing attention from the medical society. While male reproductive organs are often exposed to SRF-EMR, little is currently known about the direct effects of long-term SRF-EMR exposure on the testes and its involvement in the suppression of male reproductive potential. The present study was designed to investigate this issue by using 4G SRF-EMR in rats. A unique exposure model using a 4G smartphone achieved localized exposure to the scrotum of the rats for 6 h each day (the smartphone was kept on active talk mode and received an external call for 1 min over 10 min intervals). Results showed that SRF-EMR exposure for 150 days decreased sperm quality and pup weight, accompanied by testicular injury. However, these adverse effects were not evident in rats exposed to SRF-EMR for 50 days or 100 days. Sequencing analysis and western blotting suggested Spock3 overexpression in the testes of rats exposed to SRF-EMR for 150 days. Inhibition of Spock3 overexpression improved sperm quality decline and alleviated testicular injury and BTB disorder in the exposed rats. Additionally, SRF-EMR exposure suppressed MMP2 activity, while increasing the activity of the MMP14–Spock3 complexes and decreasing MMP14–MMP2 complexes; these results were reversed by Spock3 inhibition. Thus, long-term exposure to 4G SRF-EMR diminished male fertility by directly disrupting the Spock3–MMP2–BTB axis in the testes of adult rats. To our knowledge, this is the first study to show direct toxicity of SRF-EMR on the testes emerging after long-term exposure.

Radiofrequency electromagnetic radiation-induced behavioral changes and their possible basis.

The primary objective of mobile phone technology is to achieve communication with any person at any place and time. In the modern era, it is impossible to ignore the usefulness of mobile phone technology in cases of emergency as many lives have been saved. However, the biological effects they may have on humans and other animals have been largely ignored and not been evaluated comprehensively. One of the reasons for this is the speedy uncontrollable growth of this technology which has surpassed our researching ability. Initiated with the first generation, the mobile telephony currently reaches to its fifth generation without being screened extensively for any biological effects that they may have on humans or on other animals. Mounting evidences suggest possible non-thermal biological effects of radiofrequency electromagnetic radiation (RF-EMR) on brain and behavior. Behavioral studies have particularly concentrated on the effects of RF-EMR on learning, memory, anxiety, and locomotion. The literature analysis on behavioral effects of RF-EMR demonstrates complex picture with conflicting observations. Nonetheless, numerous reports suggest a possible behavioral effect of RF-EMR. The scientific findings about this issue are presented in the current review. The possible neural and molecular mechanisms for the behavioral effects have been proposed in the light of available evidences from the literature.

Risk to pollinators from anthropogenic electro-magnetic radiation (EMR): Evidence and knowledge gaps

Worldwide urbanisation and use of mobile and wireless technologies (5G, Internet of Things) is leading to the proliferation of anthropogenic electromagnetic radiation (EMR) and campaigning voices continue to call for the risk to human health and wildlife to be recognised. Pollinators provide many benefits to nature and humankind, but face multiple anthropogenic threats. Here, we assess whether artificial light at night (ALAN) and anthropogenic radiofrequency electromagnetic radiation (AREMR), such as used in wireless technologies (4G, 5G) or emitted from power lines, represent an additional and growing threat to pollinators. A lack of high quality scientific studies means that knowledge of the risk to pollinators from anthropogenic EMR is either inconclusive, unresolved, or only partly established. A handful of studies provide evidence that ALAN can alter pollinator communities, pollination and fruit set. Laboratory experiments provide some, albeit variable, evidence that the honey bee Apis mellifera and other invertebrates can detect EMR, potentially using it for orientation or navigation, but they do not provide evidence that AREMR affects insect behaviour in ecosystems. Scientifically robust evidence of AREMR impacts on abundance or diversity of pollinators (or other invertebrates) are limited to a single study reporting positive and negative effects depending on the pollinator group and geographical location. Therefore, whether anthropogenic EMR (ALAN or AREMR) poses a significant threat to insect pollinators and the benefits they provide to ecosystems and humanity remains to be established.

Time-Series-Based Model and Validation for Prediction of Exposure to Wideband Radio Frequency Electromagnetic Radiation

Strength of wideband electromagnetic radiations (EMRs) generated by telecommunication systems is a time-varying process typically characterized by a seasonal behavior due to daily and weekly variations of traffic in mobile networks summed to a stationary background generated by constant-power broadcasting systems. Besides a few papers showing the existence of peak and off-peak hours in the daily exposure, there is a significant lack of scientific literature investigating how exposure changes over time, although this is key to the three main objectives: 1) to determine the time intervals when exposure levels are expected to be the highest, 2) to assess worst case exposure and ensure that measurements are run in a conservative scenario to comply with limits enforced by national laws and European guidelines, and 3) to highlight variations in traffic to allocate network resources dynamically to optimize performance. We present a time-series analysis model that makes use of measured data to build a predictor of the exposure to wideband EMR. The main result is that exposure can be predicted by a model composed of three components capturing the average exposure, the daily and half-daily periodicity (seasonal behavior), and the correlations among residuals [modeled by an AR(2) for weekdays and Sunday, and by an AR(1) for Saturday, respectively]. We observed the strength of the periodic components differs more on weekdays compared to weekends. The forecasting model can be particularly useful to predict when exposure is expected to be the highest during the day, so that measurements carried out at that time will be conservative with respect to measurements run at other times of the day, and will therefore serve as the worst case for the assessment of compliance with exposure limits.

Space distribution of radio frequency radiation from air plasma produced by nanosecond pulsed laser

Radio frequency (RF) electromagnetic radiation over range of 30∼800 MHz from laser induced breakdown of air are investigated. The RF radiation, under different laser energies, laser polarization directions and detect position are measured. It is found that a much stronger RF signals emitted from air plasma was observed at moderate laser pulse energy in our case. The measured RF signal of air plasma is found to depend on laser polarization direction and pulse energy, and the spatial distribution of RF radiation is anisotropy. Underlying physics responsible for laser parameter-dependent RF emission, rich in emission lines and anisotropy of spatial distribution of RF emission of the laser induced air plasma are discussed.