National Institutes for Quantum and Radiological Science and Technology
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Gamma-Ray Irradiation Characteristics of an Organic Olefin-Based Thermosetting Dicyclopentadiene Resin Under Vacuum Atmosphere
No full textAn organic olefin-based thermosetting dicyclopentadiene (DCP) resin named TELENE was proposed as an impregnation material for Nb3Sn magnets to reduce the training. To verify the radiation resistance of the TELENE, gamma-ray irradiation experiments and three-point bending tests were conducted on the TELENE and the CTD-101K. The TELENE mixed with Gd2O2S powder was also applied for these measurements. The gamma-ray irradiation experiment was carried out up to nearly 20 MGy at room temperature using a Cobalt-60 source at the Takasaki Advanced Radiation Research Institute in Japan. For gamma irradiation in the absence of air, all resin samples were sealed in glass tubes and evacuated. The flexural strength and flexural modulus of each resin were measured by the three-point bending test before and after gamma-ray irradiation. The pure and mixed TELENE exhibits plastic deformation before the irradiation and can withstand larger strain than the CTD-101K. After irradiation, no decrease in flexural strength was observed up to 6 MGy for the pure TELENE and up to 17 MGy for the mixed TELENE. However, their strains at fracture decreased by more than 50% after 5 MGy irradiation.journal articl
The development of a DNN-assisted track analysis system for CR-39-based space radiation dosimetry
No full textCR-39 plastic nuclear track detectors are widely used in space radiation dosimetry due to their high sensitivity to charged particles and ability to record linear energy transfer (LET) information. Conventional CR-39 analysis tools can rapidly detect particle tracks in general dosimetry, however, they are not tailored for space radiation applications that require classification of valid tracks and extraction of morphology parameters to estimate LET, motivating the use of an automated approach. In this study, we propose a Deep Neural Network (DNN)-assisted track analysis system based on the Mask Region-based Convolutional Neural Network (R-CNN) framework to automate the detection and segmentation of particle tracks in CR-39 detectors.The model was trained using a transfer learning strategy with weights pretrained on the MS COCO dataset and fine-tuned on annotated CR-39 images. It achieved mean average precision (mAP) values of 81.5 % for detection and 81.4 % for segmentation. The system demonstrated robust performance in handling overlapping tracks and significantly improved analysis efficiency, reducing the processing time for a typical sample from several hours to approximately 2 min.A comparative analysis with conventional methods showed strong agreement in track counts and absorbed dose estimates, with an average difference of 4.7 % in valid track numbers and 11.2 % in absorbed dose. The discrepancy in dose estimation was primarily attributed to differences in ellipse fitting methods used for LET calculations. Despite challenges in classifying small or low-contrast tracks, the proposed DNN-assisted method offers a promising solution for high-throughput, reliable, and standardized CR-39 track analysis in space radiation dosimetry.journal articl
Carbon Ion Versus Photon-based Stereotactic Ablative Radiation Therapy for Patients with Choroidal Melanoma.
No full textTo our knowledge, no study has compared the treatment outcomes of carbon ion radiation therapy (CIRT) and photon-based stereotactic ablative radiation therapy (SABR) in patients with choroidal melanoma. This study aimed to evaluate the treatment outcomes of patients with choroidal melanoma treated with CIRT or photon-based SABR.journal articl
霊長類における内発的動機づけメカニズムに迫るバーチャルリアリティ実験パラダイムの開発
No full text従来の霊長類動機づけ研究では、水や食餌といった外的報酬に基づく報酬動機づけが主に注目されてきた。一方、外的報酬を伴わない内発的動機づけメカニズムは未だ十分に解明されていない。われわれはサルの自発的探索行動を引き出すVR実験パラダイムを独自開発し、霊長類の内発的動機づけに迫りたいと考えている。本講演では、開発の現状と知見を紹介し、VR×化学遺伝学×AI技術による新たな霊長類動機づけ研究の可能性を議論する。PRIMATECH2026conference presentatio
H-mode operation scenarios in JT-60SA initial research phase predicted by integrated core-pedestal-SOL/divertor simulation
No full textAn integrated simulation encompassing core-pedestal-SOL/divertor regions was performed for the first time in the world to establish H-mode operation scenarios in the JT-60SA initial research phase. The simulation demonstrated that the baseline H-mode scenario will achieve its target performance parameters for normalized beta β_N≥1.8 and energy confinement factor H_98y2≥1, while maintaining divertor heat flux well below maximum allowable limit q_∥<10MW/m^2 through controlled extrinsic impurity gas injection. This accomplishment addresses both ITER/DEMO-relevant operational objectives and scientific research priorities. The predictions were enabled by implementing advanced models and codes that analyze the complete plasma volume, with specific focus on achieving compatible density predictions between the SOL/divertor and pedestal regions to optimize both plasma performance and divertor heat load reduction. This integrated simulation framework significantly enhances predictive capabilities for future tokamak operations, providing essential insights for advancing research at JT-60SA, ITER, and next-generation fusion reactors.23rd Workshop on Burning Plasma Simulation Initiativeconference presentatio
Assessment of antioxidant functions of food using electron paramagnetic resonance spectrometry: Verification using vinegar samples
No full textThe abilities of food products to cancel superoxide (O2•-) and the hydroxyl radical (•OH) and directly reduce stable nitroxyl radicals were assessed in the present study using electron paramagnetic resonance (EPR)-based methods. The antioxidant functions of vinegar samples, including one- and two-year-fermented black vinegar, were also examined.The abilities of the vinegar products to cancel O2•- were in the order of two-year-fermented black vinegar ≈ one-year-fermented black vinegar > standard vinegar. Standard vinegar, one-year-fermented black vinegar, and two-year-fermented black vinegar did not reduce the stable nitroxyl radical. Apple-flavored black vinegar, containing 300 mg/100 g of ascorbic acid, directly reduced the stable nitroxyl radical. The ability of two-year-fermented black vinegar to cancel •OH was slightly stronger than those of one-year-fermented and standard vinegars. •OH-canceling ability appeared to be due to the sugars and/or proteins present in sample vinegars, particularly apple-flavored black vinegar, which had a high carbohydrate content. The addition of vinegar to the reaction mixture enhanced the reduction of TEMPOL in the presence of GSH at a hyperthermal temperature in the order of apple-flavored black vinegar >> two-year-fermented black vinegar > one-year-fermented black vinegar > standard vinegar. The reduction of TEMPOL was attributed to the cancellation of H2O2, except for apple-flavored black vinegar, which directly reduced TEMPOL. Collectively, the present results suggest that fermentation increases the antioxidant ability of vinegar. The combination of EPR methods described herein is feasible for visualizing the antioxidant activities of food samples.journal articl
Melatonin as a Guardian of Mitochondria: Mechanisms and Therapeutic Potential in Neurodegenerative Diseases
No full textMitochondrial dysfunction is a key early pathological process in neurodegenerative diseases (NDs), leading to oxidative stress, impaired energy metabolism, and neuronal apoptosis prior to the onset of clinical symptoms. Although mitochondria represent important therapeutic targets, effective interventions targeting mitochondrial function remain limited. This review summarizes current evidence regarding the mechanisms by which melatonin protects mitochondria and evaluates its therapeutic relevance, with a primary focus on Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease—the major protagonists of NDs—while briefly covering other NDs such as amyotrophic lateral sclerosis, multiple sclerosis, and prion diseases. Melatonin selectively accumulates in neuronal mitochondria and exerts neuroprotection through multiple pathways: (1) direct scavenging of reactive oxygen species (ROS); (2) transcriptional activation of antioxidant defenses via the SIRT3 and Nrf2 pathways; (3) regulation of mitochondrial dynamics through DRP1 and OPA1; and (4) promotion of PINK1- and Parkin-mediated mitophagy. Additionally, melatonin exhibits context-dependent pleiotropy: under conditions of mild mitochondrial stress, it restores mitochondrial homeostasis; under conditions of severe mitochondrial damage, it promotes pro-survival autophagy by inhibiting the PI3K/AKT/mTOR pathway, thereby conferring stage-specific therapeutic advantages. Overall, melatonin offers a sophisticated mitochondria-targeting strategy for the treatment of NDs. However, successful clinical translation requires clarification of receptor-dependent signaling pathways, development of standardized dosing strategies, and validation in large-scale randomized controlled trials.journal articl
Characteristics of passive dosimeters for ultra-high dose rate protons and electrons
No full textA practical and accurate dosimetry method is essential to support basic research aimed at advancing ultra-high dose rate radiation therapy (UHDR, >40 Gy/s). However, applying conventional dosimetry methods which have been developed and characterized under low dose rates (approximately 0.03 Gy/s) directly to these conditions remains highly challenging. The dose and dose rate dependences of passive dosimeters, optical stimulated luminescence dosimeter (OSLD), Fricke chemical dosimeter and cellulose triacetate (CTA) film dosimeter, were investigated for dosimetry under UHDR irradiation of proton and electron beams. Under 230 MeV proton irradiation with an average dose rate of 50 Gy/s, no dose rate dependence was observed in either OSLD or Fricke dosimeter. The applicable dose range was below 10 Gy for OSLD and above 10 Gy for the Fricke dosimeter. In contrast, under 14 MeV electron irradiation with an instantaneous dose rate exceeding 100 kGy/s, dose rate dependence was observed in OSLD and CTA film dosimeter, while the Fricke dosimeter remained dose rate independent. Since the observed dose-rate dependence in OSLD appears to contradict existing theoretical models, further experimental validation is required. These results demonstrate that the dose assessment at the accelerator facilities can be effectively characterized using a combination of OSLD and Fricke dosimeters, covering a wide range of proton dose and dose rate, whereas the Fricke dosimeter is applicable for dosimetry of high-intensity short-pulsed electron beam.journal articl
Effect of a law amendment on dosimeter wearing in medical radiation workers: observational study
No full textObjectives To evaluate the impact of a law amendment that reduced the eye lens dose limit on the use of personal dosimeters among radiation workers in medical settings.Materials and methods A repeated cross-sectional survey was conducted at medical institutions across three periods: before the law amendment (control) and during the promulgation and implementation periods. Surveyors (radiological technologists) at each participating medical institution recorded dosimeter-wearing status among radiation workers. Data were collected via mail or email and analysed. The observed workers included physicians, nurses, and radiological technologists.Results The surveys were collected from 1194 workers in the control period, 1374 in the promulgation period, and 1194 in the implementation period, totalling 3762 workers. Post-law amendment, the overall wearing rate of primary personal dosimeters signi cantly increased from 64.6% to 77.9% (p < 0.001). Signi cant increases in wearing rates were observed among physicians and radiological technologists (p < 0.001). Among occupations, physicians showed the lowest wearing rates across all periods (control: 35.8%, promulgation: 56.7%, implementation: 62.6%), whereas radiological technologists showed the highest (control: 92.7%, promulgation: 98.5%, implementation: 99.5%). Regarding physician specialities, orthopaedic surgery exhibited the lowest compliance (control: 11.3%, promulgation: 35.4%, implementation: 24.7%). The proportion of workers without provision of a personal dosimeter declined from 5.9% to 1.9% (p < 0.001).Conclusions Despite overall improvement following the law amendment, low compliance among physicians, particularly in orthopaedics, indicates the need for targeted interventions. Critical relevance statement Although dosimeter-wearing rates improved after Japan’s eye dose limit revision, persistent low physician compliance—especially in orthopaedics—highlights the need for targeted strategies to strengthen radiation protection in clinical practice.journal articl
ネガティブ・ケイパビリティの認知科学的再構成：量子ゼノン効果の構造的メタファーに基づく理論的展望
No full texthis article offers a theoretical reconceptualization o f negative capability (NC), understood as the capacity to remain withindeterminacy and suspend premature closure, within a cognitive scientific framework. While N C has traditionally beendiscussed i n poetic and clinical contexts, the argument situates i t in relation to indeterminacy and introduces the QuantumZeno effect (QZE) as a structural model for describing the interplay between observation and state transitions. NC i scharacterized here as a metacognitive capacity that modulates transitions between cognitive states through the frequencyand timing o f observation o r evaluation. B y articulating the theoretical intersections among NC, indeterminacy, and QZE,the article recasts NC as a form o f cognitive tolerance of, and regulatory control over, undecided states under indeterminacy,shaped b y temporal and attentional dynamics. This framework illuminates how the mind can sustain ambiguity, delaycommitment, and reorganize meaning over time, and i t points toward future directions for modeling, operationalization,and empirical investigation o f N C within cognitive science.journal articl