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East Asia is a major source of dust accounting for 20% of the global dust emission. Work on reconstructing past changes in dust transport in East Asia is complicated by difficulties in distinguishing local sedimentation from aerial material and lack of suitable material for age determination. Here, we address these issues and present a new dust proxy record from Lake Motosu, located on the Pacific side of Japan. The record is anchored by a high‐quality tephra and radiocarbon chronology. Because Lake Motosu is situated in a quartz‐free basaltic volcanic province, all quartz deposited in the lake is likely to be aerially sourced, and variations in quartz content should reflect past changes in dust transport. Our new record detects a low dust deposition event from 3.0 to 2.0 ka. This event corresponds to elevated sea surface temperature in the Sea of Japan and climate conditions similar to a negative phase of the Arctic Oscillation, indicating an association with the weakened Westerlies and with less frequent dust storms in the source region. The increase in spatial resolution of past dust transport reconstructions will further improve our understanding of the mechanism related to dust emission from East Asia. Plain Language Summary: One potential proxy for understanding past changes in atmospheric conditions is aeolian dust. The climate variability links between non‐contiguous geographic regions and strong constraints on geological ages are required to better contribute to the understanding of dust transport. Here, the dust deposition history of the past 8,000 years at Lake Motosu was obtained by quantitative X‐ray diffraction analysis to determine the amount of quartz in the sediments. There is no local source of quartz to Lake Motosu, so we consider that quartz is transported to the lake in the atmosphere. The amount of dust deposition to the Lake Motosu has persistently decreased between 3 and 2 thousand ago. This sustained decrease in dust deposition may be caused by conditions similar to a negative phase of the Arctic Oscillation. This interpretation is consistent with other proxy records from East Asia. Key Points: Dust deposition history of the past 8 kyr at Lake Motosu was obtained by quantifying quartz amount by X‐ray diffraction analysisReduced amounts of dust accumulation are recognized between 3 and 2 ka, suggesting the Westerlies were away from Lake MotosuClimate conditions similar to a negative phase of the Arctic Oscillation may be the cause of the sustained decrease in dust deposition [ABSTRACT FROM AUTHOR]

Electrostatic discharge (ESD) has been known to cause electromagnetic noise against electronic equipment and devices even before the technical concept of electromagnetic compatibility (EMC) was established 68 years ago in the United States and 48 years ago in Japan, while the ESD still continues to be studied as one of the most significant issues that should be solved in EMC areas. This is largely because the underlying nature of ESD has yet to be essentially elucidated from an EMC perspective. On the other hand, as an academic research organization on EMC in Japan, a Technical Committee named ‘EMCJ’ on ‘Environmental Electromagnetic Engineering’ was founded in 1976 in both the Institute of Electrical Engineers of Japan (IEEJ) and the Institute of Electronics and Communication Engineers or the present IEICE (Institute of Electronics, Information and Communication Engineers) to address EMC concerns. Since then, the EMCJ has been jointly conducting EMC research activities under the IEICE as the nominating body and the IEEJ as the associative body, whereas the EMCJ of IEEJ was dissolved in 1999 to form a new Technical Committee on EMC (TC‐EMC) in order to deal with EMC issues appropriate to the IEEJ. In this review, to mark the 25th anniversary of the IEEJ Technical Committee on EMC (TC‐EMC) in 2024, the EMC research efforts and activities that the TC‐EMC has conducted over the past 25 years from January 2000 to March 2024 are surveyed from 1272 technical papers presented at the technical meetings. Furthermore, among the ESD issues identified in these technical papers, the latest case studies utilizing ‘spark resistance laws’ that allow the analysis of the initial behavior of sparks, in which a spark is the essence of ESD and is the key to open the door to elucidate the phenomenon, particularly from an EMC perspective, are reviewed. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In compliance assessments of radio-frequency exposure from cellular-phone-base station antennas, the root of 6-min time average of the squared electric fields is commonly required. Under the assumption that the time-varying electric fields belong to an ergodic process, a new approach has been proposed to estimate the 6-min time average from the ensemble average of the squared electric fields based on amplitude probability distribution (APD) measurements for a shorter time, much less than 6 min. The usefulness of the approach has been demonstrated at the 800-MHz band and the 1.5-GHz band, and the results have shown that by using a fast sampling rate, 1-min APD measurements could give a good estimate of the 6-min time average with an accuracy of within [+ or -] 10%. Index Terms--Amplitude probability distribution (APD), base station antenna, cellular phone, electric field intensity assessment.

For investigation of possible bio-effects of the 2-GHz wideband code division multiple access cellular system on pregnant and newborn rats, we have developed an unrestrained whole-body exposure setup, which employs two dipole antennas to induce a circularly polarized field at the location of the rats. The dosimetric results, by using the finite-difference time-domain method in conjunction with anatomical rat models, have confirmed the realization of a circular polarization in the exposure space, and have also revealed that the exposure setup can maintain a relative variation of the whole-body average specific absorption rate (SAR) within [+ or -]60% of the designed average level for various positions of rats. These findings show that the exposure setup is reasonable and acceptable in view of the actual SAR variation in a human body due to RF exposure from base stations. Index Terms--Bio-effect of electromagnetic field, circular polarization, pregnant rat, RF, whole-body exposure setup.

This paper investigates the correlation between maximum temperature increases and peak spatial-average specific absorption rates (SARs), calculated by different average schemes and masses. For evaluating the effect of mass on the correlation properly, a three-dimensional Green's function is presented. From our computational investigation, no best average mass for peak spatial-average SAR exist from the aspect of the correlation with maximum temperature increase. This is attributed to the frequency dependent penetration depth of EM waves. Maximum temperature increase in the head including the pinna is reasonably correlated with peak spatial-average SARs for most average schemes and masses considered in this paper. Maximum temperature increase in the head only (excluding the pinna) is reasonably correlated with peak 10-g SARs for the average schemes considered in this paper. The rationale for this result is explained using the Green's function. The point to be stressed here is that the slope correlating them is largely dependent on the average scheme and mass. Additionally, good agreement is observed in the slopes obtained by using two head models, which have been developed at Osaka University and Nagoya Institute of Technology. However, weak correlation is observed for the brain, which is caused by the difference of the positions where peak SAR and maximum temperature increase appear. The 95th percentile values of the slope correlating maximum temperature increases in the head or brain and peak spatial-average SAR are quantified for different average schemes and masses. Index Terms--Bio-heat transfer equation, human exposures, specific absorption rate (SAR), temperature increase.

In designing an in vivo near-field exposure setup for testing biological effects of cellular phones, one generally uses a small still animal because a plastic holder is used to restrain it. One also takes no account of the exposure box with radio wave absorbers as well as the plastic holder. In this paper, for the in vivo exposure setup developed in the National Institute of Information and Communications Technology (NICT), which was used for testing the promoting effect of 1.439- and 1.95-GHz digital cellular phones on rat brain carcinogenesis, we investigated the effects of the above-mentioned factors on the dosimetry design using the finite-difference time-domain (FDTD) method in conjunction with an anatomical rat model. As a result, we found that the specific absorption rate (SAR) averaged in the brain was 18% higher at maximum than the previously designed level due to the existence of the exposure box and the plastic holder and that the variation due to the rotation of the rat's head inside the plastic holder was within 10%. The backward movement of the rat along the plastic holder was more serious, which yielded a decrease of nearly 20% for the average SAR in the brain. Index Terms--Cellular phone, in vivo exposure setup, specific absorption rate (SAR), uncertainty evaluation.

This paper discusses the correlation between peak spatial-average specific absorption rate (SAR) and maximum temperature increase for antennas attached to the human trunk. Frequency bands considered are 150, 400, and 900 MHz, which are assigned for occupational communications. This problem is throughly investigated with the aid of Green's function. In particular, the effect of variation of thermal constants on the temperature increase is revealed by using one-dimensional model. Computational results suggests that one of the most dominant factors which affect the correlation between peak SAR and maximum temperature increase is blood flow in tissues. This is confirmed by considering a three-dimensional realistic human body model. Uncertainties caused by the calculation of peak SAR and the difference in the body model shape are also quantified. Index Terms--Blood flow, Green's function, specific absorption rate (SAR), temperature increase.

The specific absorption rates (SAR) determined computationally in the specific anthropomorphic mannequin (SAM) and anatomically correct models of the human head when exposed to a mobile phone model are compared as part of a study organized by IEEE Standards Coordinating Committee 34, SubCommittee 2, and Working Group 2, and carried out by an international task force comprising 14 government, academic, and industrial research institutions. The detailed study protocol defined the computational head and mobile phone models. The participants used different finite-difference time-domain software and independently positioned the mobile phone and head models in accordance with the protocol. The results show that when the pinna SAR is calculated separately from the head SAR, SAM produced a higher SAR in the head than the anatomically correct head models. Also the larger (adult) head produced a statistically significant higher peak SAR for both the 1- and 10-g averages than did the smaller (child) head for all conditions of frequency and position. Index Terms--FDTD methods, IEEE standards, phantom, simulation, software standards, specific absorption rate (SAR), specific anthropomorphic mannequin (SAM).

In electromagnetic dosimetry of children heads for mobile telephones, the dielectric properties of biological tissues for adults are so far being used due to the lack of the ones of children. In this paper, we derived an empirical formula according to Lichtenecker's exponential law for the complex permittivity of various tissues as a function of the hydrated rate or the total body water (TBW). We first examined its validity using the data measured by Peyman et al. for rats, and then applied the formula to the dielectric properties of 7-year-old and 3-year-old child head models by means of the relationship between the TBW and the age. With the dielectric properties for children derived in such an approach, we analyzed numerically the spatial peak specific absorption rate (SAR) for a 900-MHz mobile telephone in adult and child head models. As a result, we found that the dielectric properties for children do not affect significantly the 1- or 10- g averaged spatial peak SAR as well as the penetration depth. The finding could be qualitatively explained as cancellation of the increased conductivity and decreased electric field penetrating into the tissue because of the same degree of increase between the conductivity and permittivity in children compared to adults. Even in an extreme case, the age effect on the spatial peak SAR of dielectric properties is still within 10%. Index Terms--Children, dielectric property, FDTD method, mobile telephone, penetration depth, specific absorption rate.

This paper investigates the correlation between the peak specific absorption rate (SAR) and the maximum temperature increase in head models of adults and children due to a dipole antenna. Much attention is paid to the effect of variation of electrical and thermal constants on the correlation for the child models, since these constants of child tissues are different from those of adult tissues. For investigating these correlations thoroughly, a total of 1400 situations are considered for the following six models: 3-year-old child, 7-year-old child, and adult models developed at the Nagoya Institute of Technology and the Osaka the University. The numerical results are analyzed on the basis of statistics. We find that the maximum temperature increases in the head can be estimated linearly in terms of peak SAR averaged over 1- or 10-g of tissue. In particular, no clear difference is observed between the adult and child models in terms of the slopes correlating the maximum temperature increase with the peak SAR. Also, the effect of electrical and thermal constants of tissue on these correlation is found to be marginal. Further, we discuss possible maximum temperature increases in the head and brain for SAR limits prescribed in safety guidelines. For the adult model developed at the Osaka Univ., these are found to be 0.26 [degrees]C and 0.10 [degrees]C at the SAR value of 1.6 W/kg for 1-g cubic tissue and 0.59 [degrees]C and 0.21 [degrees]C at the SAR value of 2.0 W/kg for 10-g cubic tissue. Similarly, for the 3-year-old child model at Osaka Univ., these are 0.23 [degrees]C and 0.11 [degrees]C for the value of 1-g SAR and 0.53 [degrees]C and 0.20 [degrees]C for the value of 10-g SAR. Index Terms--Bioheat equation, dipole antenna, dosimetry, specific absorption rate (SAR), temperature increase.

In this paper, high-frequency (HF) and microwave electromagnetic (EM) fields in experimental fusion facilities were statistically measured, and the exposure levels were compared with safety guidelines to ensure workers' safety. Since leaked EM fields have time-varying characteristics whose amplitudes vary according to a stochastic process, a measurement of their amplitude probability distribution (APD) was conducted. An approach was then presented to derive from the measured APD the specific absorption rate (SAR) in an exposed human body. The statistically-averaged whole-body-averaged SAR showed that the leaked field intensities were low enough to not cause any thermal hazards for the workers in the specific EM environment. The statistically averaged SAR also showed fair agreement with the SAR derived from the time average over 6 min as specified in the safety guidelines. This finding suggests the usefulness of the APD measurement in lieu of a field measurement over a 6-min period because the APD can be obtained in a time period much less than 6 min. Index Terms--Amplitude probability distribution (APD), electromagnetic environment, experimental fusion facilities, field leakage, human exposure, statistically averaged specific absorption rate (SAR).

In most in vivo exposure setups for testing biological effects of cellular telephones on a small animal, a plastic holder is commonly used for restraining the small animal in order to keep a constant near-field exposure. Although the plastic holder should affect the specific absorption rate (SAR) in the small animal, few researchers have considered its influence in their exposure setup design or dosimetry evaluation. We previously developed an in vivo exposure setup for testing the promoting effect of digital cellular telephones on mouse skin carcinogenesis. In this paper, the influence of a plastic holder for restraining the mouse in the exposure setup was investigated numerically and experimentally. The numerical investigation was conducted by using the finite-difference time-domain (FDTD) method together with a realistically shaped mouse model. The validity of the FDTD modeling was verified by the antenna impedance measurement. As a result, an increase of 18% on the peak SAR was found due to the presence of the mouse holder. Index Terms--Biological effect, cellular telephone, in vivo exposure setup, plastic holder, specific absorption rate.

The controversy on the dosimetry in children's heads for mobile telephones is still inconsistent. Gandhi's group reported a considerable increase of the spatial peak specific absorption rate (SAR) in children's heads, while Kuster's group claimed that there was not a significant difference in the SAR between children and adults. In this paper, based on Japanese children's statistical data on external shapes of heads, we newly developed two kinds of children's models from a Japanese adult head model. Using the children's head models, we calculated the local peak SAR under the same conditions as those previously employed by Gandhi's and Kuster's groups. Compared to the local peak SAR in the adult head model, we found a considerable increase in the children's heads when we fixed the output power of the monopole-type antenna, but no significant differences when we fixed the effective current of the dipole-type antenna. This finding suggests that the contradictory conclusions drawn by the above two groups may be due to the different conditions in their numerical peak SAR calculations. Index Terms--Children, dosimetry, mobile telephone, specific absorption rate (SAR).

With a 6 GHz band high resolution magnetic near‐field probe (XF‐R 3‐1) produced by Langer, the transient magnetic fields due to collision ESDs (electrostatic discharges) between metal balls at a charging voltage of 600 V were measured near the spark point to investigate a dipole radiation mechanism. In this study, as an object of considering the measured magnetic field waveforms, two different equivalent circuits of the magnetic near‐field probe are derived based on the probe response waveform observed by a TDR (time domain reflectometer) with a 10 ps rise‐time pulse and the probe reflection coefficient measured with a 26 GHz network analyzer. Waveform conversion formulae from the probe output voltage to the magnetic field are given. The validity of the conversion methods is verified by comparing the measured conversion waveforms and their frequency spectra in addition to the converted spectra by the Langer field correction curve with the calculated waveforms of the transient magnetic far‐fields from a dipole model consisting of image charge pairs and the Rompe‐Weizel spark resistance formula. The probe conversion formulae presented here are valid within the frequency range of the 6 GHz probe band, however, beyond the band the resonance peaks at multiple frequencies over 8 GHz appear on the spectra, which causes damping oscillations peculiar to the probe with multiple frequencies to the time domain waveform. [ABSTRACT FROM AUTHOR]

Nuclear fusion research requires the production of high-temperature plasma. One of the plasma heating methods is the use of radio frequency (RF) waves. The RF wave heating system uses a high-power amplifier, which poses a concern about the leakage electromagnetic fields. Therefore, a new wide-area multipoint electromagnetic monitoring system using personal RF monitors has been developed. The developed monitoring system was applied to the megawatt-class amplifiers for the “ion cyclotron range of frequency” (ICRF) heating system in the frequency range of ion cyclotron resonance from 30 to 40 MHz. As a result, the leakage magnetic field was less than the measurement sensitivity during the plasma experiment, in which the leakage electric field was detected with sufficient sensitivity. The leakage electric field becomes larger as the RF forward power increases, and thus the electric field would be radiated through the stub and/or high voltage supply line connected to the anode of tetrode in the ICRF amplifier. The electric field around the ICRF amplifiers did not exceed the reference level of International Commission on Non-Ionizing Radiation Protection (ICNIRP). The developed wide-area multipoint monitoring system will be useful for monitoring the leakage RF electromagnetic fields around the ICRF heating system at the future fusion devices. [ABSTRACT FROM AUTHOR]

Organic matter in lake sediments contains information that can be used to reconstruct lake environmental histories over decades or centuries. In this study, we used organic geochemical proxies (i.e., total organic carbon [TOC], TOC/total nitrogen [TN] atomic ratios [C/N], stable carbon isotope ratios of TOC [δ13CTOC] and palmitic acid [δ13CC16:0], and nitrogen isotope ratios of bulk sediment [δ15Nbulk]) in sediments from Lake Kawaguchi, Japan, to reconstruct detailed histories of the organic matter accumulation and lake productivity over the past 130 years. Vertical profiles of the mass accumulation rate (MAR) of TOC in the eastern lake basin (core KAW14-7A) showed parallel increases with the C/N ratio from the 1960s to the 1980s, indicating an accelerated delivery of terrestrial organic matter via anthropogenic land-use change. In contrast, the C/N ratios in the western and central basins (cores KAW14-1A and KAW14-4B, respectively) were almost constant prior to the 1980s, suggesting that the increasing trends in the TOC MAR values in these cores are most likely attributable to the onset of eutrophication associated with rapid economic growth after the mid-1950s. On the other hand, the δ15Nbulk showed a gradual increase from the late 1870s, providing evidence for anthropogenic nitrogen input to the lake prior to the apparent eutrophication. After the 1960s–1970s, the δ15Nbulk values rapidly increased, demonstrating water deterioration associated with the direct nutrient discharge into the lake from domestic wastewater. The δ13CC16:0 profiles displayed similar increasing trends to δ15Nbulk from the mid-1960s, demonstrating a close relationship between lake productivity and anthropogenic nitrogen input in Lake Kawaguchi. Our geochemical records as a whole clearly show high algal productivity and enhanced deposition of organic matter in recent decades, suggesting that the amelioration of the lake water is a likely consequence of the transfer of nutrients to the sediment by enhanced productivity, rather than a decrease in the amount of nutrient inflow into the lake. [ABSTRACT FROM AUTHOR]

Tsunami deposits preserved in the geological record provide a more comprehensive understanding of their patterns of frequency and intensity over longer timescales; but recognizing tsunami deposits can prove challenging due to post‐depositional changes, lack of contrast between the deposits and surrounding sedimentary layers, and differentiating between tsunami and storm deposition. Modern baseline studies address these challenges by providing insight into modern spatial distributions that can be compared with palaeotsunami deposits. This study documents the spatial fingerprint of grain size and foraminifera from Hasunuma Beach and the Kujukuri shelf to provide a basis from which tsunami deposits can be interpreted. At Hasunuma Beach, approximately 50 km east of Tokyo, the spatial distribution of three common proxies (foraminiferal taxonomy, foraminiferal taphonomy and sediment grain size) for tsunami identification were mapped and clustered using Partitioning Around Medoids cluster analysis. Partitioning Around Medoids cluster analysis objectively discriminated two coastal zones corresponding to onshore and offshore sample locations. Results show that onshore samples are characterized by coarser grain sizes (medium to coarse sand) and higher abundances of Pararotalia nipponica (27 to 63%) than offshore samples, which are characterized by finer grain sizes (fine to medium sand), lower abundances of Pararotalia nipponica (2 to 19%) and Ammonia parkinsoniana (0 to 10%), higher abundances of planktonics (15 to 58%) and species with fragile tests including Uvigerinella glabra. When compared to grain‐size and foraminiferal taxonomy, foraminiferal taphonomy; i.e. surface condition of foraminifera, a proxy not commonly used to identify tsunami deposits, was most effective in discriminating modern coastal zones (identified supratidal, intertidal and offshore environments) and determining sediment provenance for tsunami deposits at Kujukuri. This modern baseline study assists the interpretation of tsunami deposits in the geological record because it provides a basis for sediment provenance to be determined. [ABSTRACT FROM AUTHOR]