Nippon Bunri University

The system of radiological protection (the 'System') developed by the International Commission on Radiological Protection (ICRP) is built on nearly a century of efforts of numerous scientists and practitioners working together internationally. It rests on three enduring pillars: science, ethics, and experience. These pillars support the three fundamental principles that shape radiological protection strategies: justification, optimisation, and application of dose limits. Of note, optimisation of protection must be understood as a flexible and context-sensitive process, which allows identification of the appropriate level of protection, not simply the lowest dose, taking into account economic, societal and environmental factors. The System has proven effective in protecting workers, patients, members of the public, and the environment in all exposure situations. Effects of high doses, where acute injuries to healthy tissue occur, are rarely observed, and mostly due to accidental situations except for unavoidable side effects of radiotherapy. At low doses, the System is supported by application of the linear-no-threshold model. This model enables prudent (that is, carefully considered given existing uncertainties) policy decisions and estimation of risks at low doses by extrapolation from epidemiological data observed at medium and high radiation doses, acknowledging uncertainty without ignoring potential harm.

ABSTRACT Objective The mechanisms underlying therapeutic hypothermia, which protects neurons after severe brain damage, are not completely understood. Based on a previous study, hypothermia reduced the release of tumor necrosis factor (TNF)‐α and interleukin (IL)‐17. Meanwhile, hyperthermia promoted the release of TNF‐α and IL‐17. Leukocyte transmigration via the endothelium is mediated by endothelial cell junctional molecules, such as junctional adhesion molecule (JAM)‐A and vascular endothelial cadherin (VE‐cadherin), positively and negatively, respectively. In the ischemic brain, the diapedesis of leukocytes into the tissues results in enhanced postischemic brain inflammation and intensified brain injury. The current study aimed to evaluate the mechanisms underlying this treatment by assessing the effects of TNF‐α and IL‐17 on brain microvascular endothelial cell (BMVEC) junctional molecule and the effects of hypothermia and hyperthermia on its expression. Methods The expression of JAM‐A and VE‐cadherin, which are BMVEC junctional molecules, was measured at the protein level via immunocytochemistry. Results TNF‐α and IL‐17 increased the expression of JAM‐A in BMVECs in a concentration‐dependent manner. Compared with normothermia, hypothermia did not affect the expression of JAM‐A and VE‐cadherin in BMVECs stimulated with TNF‐α or IL‐17. Meanwhile, hyperthermia reduced the basal expression of VE‐cadherin in BMVECs, with this expression being further reduced by stimulation with IL‐17. Conclusions The hypothermic suppression of TNF‐α and IL‐17 release may decrease JAM‐A expression in BMVECs. Meanwhile, hyperthermia itself may decrease VE‐cadherin expression in BMVECs. The former may contribute to suppressing, while the latter may promote, leukocyte extravasation.

The physical mechanism underlying wire rope cut-in in multilayer drums was experimentally investigated. Although the wire rope appears to be correctly spooled on the drum, hoisting the load can cut the spooling wire rope into multiple layers, leading to mis-wrap or entanglement. Such irregularities may result in rope damage or reverse winding, necessitating repairs. The hand winch testing results indicated that LEBUS drums exhibit greater resistance to cut-in compared to ungrooved drums; in particular, LEBUS drums require a lower pre-tension load to prevent cut-in than ungrooved drums. Moreover, in the LEBUS, the spooling wire rope typically cuts through in a single layer, whereas in ungrooved drums, the spooling wire rope cuts deeper through multiple layers, increasing the likelihood of entanglement or reverse winding. The simultaneous slipping of several wraps in the surface layer was observed as a contributing factor to cut-in in LEBUS drums.

Background: A NaI(Tl) survey meter was used in the pediatric thyroid screening conducted after the Fukushima Daiichi Nuclear Power Plant accident. However, this measurement method has the weakness that it is difficult to selectively identify 131I. In this study, we analyzed the performance of an energy-analyzable NaI(Tl) spectrometer using the Particle and Heavy Ion Transport code System (PHITS), which allows Monte Carlo simulation of radiation transport.Materials and Methods: The spectrum of energy emitted by the NaI(Tl) spectrometer was simulated for a total energy absorption peak by adjusting factors that affect pulse wave height. From these simulation results, the detection limits of the NaI(Tl) spectrometer were obtained using Monte Carlo simulation.Results and Discussion: The energy spectrum results were reproduced with an accuracy of 0.1% to 44.0% for total energy absorption peaks. The calculated detection limit for 131I activity equivalent to 100 mSv in the thyroid under a 0.2 μSv· hr−1 ambient dose rate was approximately 80–90 Bq, which could be detected for up to 38 days after 131I intake in a 1-year-old child.Conclusion: This study demonstrated that pediatric thyroid screening using an NaI(Tl) spectrometer can practically provide greater accuracy than NaI(Tl) survey meters.

Abstract. Wildfires are among the most influential disturbances affecting ecosystem structure and biogeochemical cycles in Siberia. Therefore, accurate fire modeling via dynamic global vegetation models is important for predicting greenhouse gas emissions and other biomass-burning emissions to understand changes in biogeochemical cycles. We integrated the widely used SPread and InTensity of FIRE (SPITFIRE) fire module into the spatially explicit individual-based dynamic global vegetation model (SEIB-DGVM) to improve the accuracy of fire predictions and then simulated future fire regimes to better understand their impacts. The model can reproduce the spatiotemporal variation in biomass, fire intensity, and fire-related emissions well compared to the recent satellite-based estimations: aboveground biomass (R2=0.847, RMSE =18.3 Mg ha−1), burned fraction (R2=0.75, RMSE=0.01), burned area (R2=0.609, RMSE =690 ha), dry-matter emissions (R2=0.624, RMSE =0.01 kg DM m−2; dry matter), and CO2 emissions (R2=0.705, RMSE =6.79 Tg). We then predicted that all of the 33 fire-related gas and aerosol emissions would increase in the future due to the enhanced amount of litter as fuel load from increasing forest biomass production under climate forcing of four Representative Concentration Pathways: RCP8.5, RCP6.0, RCP4.5, and RCP2.6. The simulation under RCP8.5 showed that the CO2, CO, PM2.5, total particulate matter (TPM), and total particulate carbon (TPC) emissions in Siberia in the present period (2000–2020) will increase relatively by 189.66±6.55, 15.18±0.52, 2.47±0.09, 1.87±0.06, and 1.30±0.04 Tg species yr−1, respectively, in the future period (2081–2100) and the number of burned trees will increase by 100 %, resulting in a 385.19±40.4 g C m−2 yr−1 loss of net primary production (NPP). Another key finding is that the higher litter moisture by higher precipitation would relatively suppress the increment of fire-related emissions; thus the simulation under RCP8.5 showed the lowest emissions among RCPs. Our study offers insights into future fire regimes and development strategies for enhancing regional resilience and for mitigating the broader environmental consequences of fire activity in Siberia.

Step adhesive joints have a special characteristic quite different from other joints. When initial delamination occurs in other joints such as butt, lap and scarf joints, final failure always occurs. In these cases, the external stress causing initial delamination σcInitial is equal to the final failure stress as σcFinal = σcInitial. However, in step joints, the final failure stress σcFinal can be greater than the initial delamination stress σcInitial < σcFinal. To clarify the adhesive improvement mechanism, first, this paper discusses the ISSF (Intensity of Singular Stress Fields) for fully bonded step joint by varying the number of steps NS. Second, the singular stress field causing 2nd debonding is discussed by analyzing partially delaminated step joint. The results show that 2nd debonding requires larger external load than the initial debonding as σcInitial < σcFinal. This is because under the same external load the singular stress causing the 2nd deboning is smaller than the one causing the initial debonding. When NS≥6 and suitable overlap length, the final bond strength σcFinal can be more than 3.6 ∼ 4.4 times larger than the initial delamination stress σcInitial≪σcFinal resulting in much larger bond strength.

Statistical benchmark data are necessary when considering the basis for radiation protection criteria based on calculated risks. We herein focused on baseline mortality and incidence cancer rates as benchmark data collected from 33 countries. Furthermore, we calculated the lifetime mortality and incidence risks and disability-adjusted life years (DALYs) for all solid cancers, colon cancer, lung cancer, breast cancer, thyroid cancer, and leukemia using the baseline cancer rates and compared them among the countries. The results showed that the lifetime mortality and incidence risks and DALYs for all solid cancers differed among the countries by a factor of 2–4 for males and 2–3 for females; these were low in less-developed countries. Our study proposed that health risk based on baseline cancer rates should be the benchmark for comparing radiation cancer risks.

Roller massage has been recognized as an effective intervention for managing various conditions. However, data on the effects of roller massage on the dynamic mechanisms of the myofascial and soft tissues of the lower back are limited. This study aimed to examine the effect of the self-myofascial release of the lower back on myofascial gliding, lumbar flexibility, and abdominal trunk muscle strength using a roller massager. This crossover study included 24 college athletes who underwent three interventions—roller massage, static stretching, and control (rest). Before and after the intervention, lumbar and fascial gliding were evaluated using ultrasonography. Long-seat anteflexion (lumbar flexibility) and abdominal trunk muscle strength were assessed. The movement velocities of the subcutaneous tissue and the multifidus muscle over time were calculated using echo video analysis software, and gliding was estimated using the cross-correlation coefficient between the velocities. Gliding, lumbar flexibility, and abdominal trunk muscle strength showed significant intervention-by-time interactions. Roller massage significantly improved gliding, lumbar flexibility, and abdominal trunk muscle strength. The self-myofascial release of the lower back using a roller massager improved the lumbar/fascia gliding, lumbar flexibility, and abdominal trunk muscle strength compared to static stretching.

BackgroundWomen with higher breast density are at higher risk of developing breast cancer. Breast density is known to affect sensitivity to mammography and to decrease with age. However, the age change and associated factors involved are still unknown. This study aimed to investigate changes in breast density and the associated factors over a 10-year period.Materials and MethodsThe study included 221 women who had undergone eight or more mammograms for 10 years (2011–2020), were between 25 and 65 years of age, and had no abnormalities as of 2011. Breast density on mammographic images was classified into four categories: fatty, scattered, heterogeneously dense, and extremely dense. Breast density was determined using an image classification program with a Microsoft Lobe’s machine-learning model. The temporal changes in breast density over a 10-year period were classified into three categories: no change, decrease, and increase. An ordinal logistic analysis was performed with the three groups of temporal changes in breast density categories as the objective variable and the four items of breast density at the start, BMI, age, and changes in BMI as explanatory variables.ResultsAs of 2011, the mean age of the 221 patients was 47 ± 7.3 years, and breast density category 3 scattered was the most common (67.0%). The 10-year change in breast density was 64.7% unchanged, 25.3% decreased, and 10% increased. BMI was increased by 64.7% of women. Breast density decreased in 76.6% of the category at the start: extremely dense breast density at the start was correlated with body mass index (BMI). The results of the ordinal logistic analysis indicated that contributing factors to breast density classification were higher breast density at the start (odds ratio = 0.044; 95% CI [0.025–0.076]), higher BMI at the start (odds ratio = 0.76; 95% CI [0.70–0.83]), increased BMI (odds ratio = 0.57; 95% CI [0.36–0.92]), and age in the 40s at the start (odds ratio = 0.49; 95% CI [0.24–0.99]). No statistically significant differences were found for medical history.ConclusionBreast density decreased in approximately 25% of women over a 10-year period. Women with decreased breast density tended to have higher breast density or higher BMI at the start. This effect was more pronounced among women in their 40s at the start. Women with these conditions may experience changes in breast density over time. The present study would be useful to consider effective screening mammography based on breast density.