National Institutes for Quantum and Radiological Science and Technology
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GHz-range AC magnetometry with an ensemble of NV centers in diamond using concatenated continuous dynamical decoupling
No full textwe discuss GHz-range AC magnetometry by applying the CCDD sequence to a large ensemble of NV centers. Under the inhomogeneities in the detuning and the driving field, the direct Rabi method leads to a rapid decay of oscillations for weak signals, thereby limiting the lower bound of the measurable amplitude. Our experimental observation confirms that the microwave dressed states generated by the CCDD enable the measurement of weaker signals. These findings provide important insights into sensitive measurement of weak GHz-range AC magnetic fields under ensemble inhomogeneities.The 18th International Conference on New Diamond and Nano Carbons 2025conference presentatio
Functional Improvement of Harsh Environment Immune All‐carbon Visible Light Detector by NV Density Enhancement through Electron Irradiation
No full textRecent advances in visible light photodetectors (PDs) marked a substantial shift towards improving their performance in harsh environments, ensuring stability in high temperatures, strong radiation, environmental corrosion, and shock impacts. In light of the superior material properties like high thermal conductivity (22 W/cmK), radiation hardness (>10 MGy), and corrosion resistance in contrast with conventional PD materials, single crystalline diamonds (SCDs) exhibit its potential for employment in harsh environments. However, its large bandgap (5.47 eV) and conflicting impurity activation towards visible energies and elevated temperatures, limit their visible energy detection capabilities. Also, the brittleness of conventional interface carbide forming ohmic contacts damper the device's performance. This study proposes a promising mechanism to enhance the visible light sensing of nitrogen-doped SCD-based visible light PDs by enhancing the nitrogen vacancy (NV) center density in the photoabsorption medium. Moreover, a harsh environment-immune all-carbon PD device structure is introduced by synchronizing highly interface-stable interdigitated nanocarbon ohmic contacts with N-doped diamond.The 18th International Conference on New Diamond and Nano Carbons 2025conference poste
Development of Ultrahigh-precision Ion Implantation System Connected with Laser-cooled Ion Source
No full textNitrogen-vacancy (NV) centers in diamond are gaining attention as room-temperature quantum bits, with potential applications in quantum sensing, quantum information processing, and quantum communication. Precise positioning of NV centers is crucial for creating efficient single-photon sources using optical resonators and quantum memories for quantum interface, etc. Generally, broad ion beam implantation through nanohole fabricated by electron beam lithography has been widely used for precise creation of NV centers. There are several reports of deterministic NV creation by using pulsed fs- or ps-laser irradiations. In addition, focusing ion beam implantation provides a route towards scalable quantum information processing. In this study, we are developing an inherently deterministic single-ion implantation method based on a linear Paul trap (LPT) as a single-ion source, since the laser-cooling technique can be applied to the trap system to obtain ultralow-emittance ions and manipulate single ions one by one.The 18th International Conference on New Diamond and Nano Carbons 2025conference poste
Effects of radiobiological 5Rs on carbon-ion radiotherapy for stage-I non-small cell lung cancer
No full text1．Purpose： Carbon-ion radiotherapy for stage-I non-small cell lung cancer (NSCLC) has been conducted at QST with 18-, 9-, 4-, and single-fraction schedules. The prescribed dose level was optimized for each fractionation schedule through dose escalation clinical studies. The purpose of this study was to investigate the effects of the radiobiological 5Rs, radiosensitivity, repopulation, repair, redistribution, and reoxygenation, on the 3-year tumor control probability (TCP) of patients with stage I NSCLC treated with carbon-ion radiotherapy.2．Methods： A meta-analysis of published clinical data of 233 NSCLC patients treated by carbon-ion radiotherapy under 18-, 9-, 4-, and single-fraction schedules was conducted. The microdosimetric kinetic model (MKM)-based cell-survival model incorporating the radiobiological 5Rs was developed to reproduce the clinical TCP data. Redistribution and reoxygenation were regarded together as a single phenomenon and termed “resensitization” in the model. The optimum interval between fractions was investigated for each fraction schedule using the determined model parameters.3．Result： The clinical TCP data for 18-, 9-, and 4-fraction schedules were reasonably reproduced by the model without the resensitization effect, whereas its incorporation was essential to reproduce the TCP data for all fraction schedules including the single fraction. The curative dose for the single-fraction schedule was estimated to be 49.0 Gy, which corresponds to the clinically adopted dose prescription of 50.0 Gy. For multi-fraction schedules, a 2-to-3-day interval is required to maximize the resensitization effect during the interval. In contrast, in the single-fraction schedule, the shorter treatment time is preferable to reduce the effect of sub-lethal damage repair during the treatment.4．Conclusion： The effects of the radiobiological 5Rs on the 3-year TCP of patients with stage-I NSCLC treated with carbon-ion radiotherapy were investigated. All 5Rs including the resensitization effect affect the clinical effectiveness of carbon-ion radiotherapy.第130回日本医学物理学会学術大会conference presentatio
Functional roles of neural circuits linking monkey prefrontal cortex and mediodorsal thalamus in cognitive flexibility
No full textAnimals must flexibly adapt to novel environments and optimize their behavior in a dynamically changing world. The prefrontal cortex (PFC) and the mediodorsal thalamus (MD) are known to support such adaptive behavior through their reciprocal connectivity and via the PFC–basal ganglia–thalamus–PFC loop. However, the specific contribution of these circuits to cognitive flexibility in primates remains unclear. To address this, we performed large-scale neuronal recordings using Neuropixels probes in a macaque monkey engaged in a modified version of the Wisconsin Card Sorting Test (WCST). Recordings targeted the dorsolateral PFC (dlPFC), along with two of its major projection sites: the parvocellular nucleus of the mediodorsal thalamus (MDpc) and the dorsal part of the caudate head (dCDh). In the WCST, the monkey was required to adapt to flexible switch between rules (based on the color or shape of a sample stimulus) and maintain the current rule to categorize subsequent stimuli, providing a robust measure of behavioral flexibility. We found that neuronal populations across all three regions encoded various task-related information, including the current rule, with particularly strong rule representation observed in MD neurons. To examine the causal roles, we employed multiplexed chemogenetic manipulations. Inhibitory Designer Receptors Exclusively Activated by Designer Drugs (hM4Di) and Pharmacologically Selective Actuator Modules (PSAM4-GlyR) were virally expressed in the dlPFC and MDpc, and neuronal activity was reversibly silenced via systemic administration of their respective agonists, deschloroclozapine and uPSEM817. Silencing the dlPFC significantly impaired WCST performance immediately after rule switches—when adaptation to a new rule was required—and concurrently reduced rule-related signals in MDpc neurons, but not in dCDh neurons. In contrast, silencing the MDpc impaired performance during rule maintenance (i.e., after successful rule acquisition), without affecting rule representations in either the dCDh or the dlPFC. These findings demonstrate distinct yet complementary roles of the dlPFC and MDpc in supporting rule-based flexible behavior. Especially, they underscore the importance of direct dlPFC-MD projections as a key neural substrate for cognitive flexibility in primates.Neuroscience2025conference poste
Chemogenetic dissection of primate prefrontal-subcortical circuits in adaptive behavior
No full textAnimals must flexibly adapt to novel environments and optimize their behavior in a dynamically changing world. The prefrontal cortex is known to support such adaptive behavior through, in coordination with subcortical regions such as the striatum and thalamus through direct and indirect connections, i.e., PFC–basal ganglia–thalamus–PFC loop and PFC-thalamus reciprocal projections. However, the specific contribution of these circuits to flexible behavior in primates remains unclear.We have recently demonstrated that neural pathways from the orbitofrontal cortex to these subcortical regions play distinct and essential roles in adapting to changes in reward contingencies by chemogenetic pathway-selective manipulation (Oyama et al., 2024).Building upon these findings, we are currently investigating whether similar principles could be applied across cortico-basal ganglia loops by examining how interactions between other prefrontal regions, such as the dorsolateral prefrontal cortex, and their corresponding subcortical targets contribute to behavioral adaptation. This work combines chemogenetic pathway-selective silencing with large-scale neural recording techniques. In this symposium, we will present our latest results from these ongoing investigations.QST霊長類研究国際シンポジウムconference 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.30th IAEA Fusion Energy Conferenceconference presentatio
Hydrogen Embrittlement of Hole-Expanded TRIP-aided Martensitic Steel Sheet
No full text穴広げ変態誘起塑性変形を施したマルテンサイト鋼の水素脆化破壊に及ぼす応力、塑性ひずみ、水素の影響を調べた。水素脆化特性は穴拡げ試験片への陰極水素チャージによって評価した。穴拡げ試験片の残留応力と塑性ひずみ分布は有限要素法によって解析した。水素の含有量は熱脱離分光計を用いて測定した。水素脆化割れは穴の端から半径方向に約3mmの位置で発生した。き裂は進展すると円周方向に発散した。き裂の形態は、主に粒界破壊と準へき開破壊の混合によって成り立っていた。水素脆化割れが発生した位置の円周方向の引張応力が最も大きく、半径方向と引張応力と静水圧応力も大きかった。穴拡げ試験片の穴の端近傍の水素含有量は穴あけや穴拡げによる塑性ひずみが大きいために最も高く、水素脆化割れが進展した位置の水素含有量は高くなかった。このように円周方向で最も高い引張応力が初期段階におけるき裂発生部位の位置と初期き裂の発生方向、およびき裂の進展方向を支配する要因となっている。水素の蓄積を引き起こす高い静水圧応力もき裂の発生を助ける可能性がある。journal articl
Type I collagen gels for assessing the combined effects of ligand concentration-dependent elasticity and fibril density on cells
No full textType I collagen (Col-I) is the most abundant fibrous protein in the extracellular matrix (ECM) and its densification is involved in the progression of various diseases and aging. Elevated Col-I concentrations increase ECM fibril density and stiffening; therefore, the effects of such changes in the microenvironment of cells require examination. To separately examine the effect of ligand concentration-dependent elasticity (C-E) and fibril density of Col-I, we developed three types of Col-I gels by introducing reagent-free radiation-induced crosslinking while adjusting the distance between the Col-I monomers or fibrils. The adhesion area of HeLa human cervical cancer epithelial cells, human induced pluripotent stem (hiPS) cells, and 3T3-Swiss albino mouse embryonic fibroblasts, tended to decrease with increasing fibril density when C-E was constant. In the absence of fibrils, the adhesion area of HeLa and 3T3-Swiss cells increased with increasing C-E, whereas hiPS cells clustered regardless of C-E. When C-E and the fibril density increased simultaneously, the adhesion area of HeLa and 3T3-Swiss cells remained unchanged due to the two opposing effects. Our results highlight the importance of evaluating the combined compositional, mechanical, and topographical effects of Col-I on cells. The developed gels will contribute to elucidating the role of Col-I in biological functions.journal articl
Investigation of preferable pressure and current density profiles for improving no-wall MHD stability of tokamak DEMO reactor including self-consistent bootstrap current calculations
No full textThe parameter settings for JA DEMO 2014 was found to be close to the ideal magnetohydrodynamics (MHD) stability limit. Therefore, this study investigated the trend in the preferable current density and pressure profiles to improve the ideal MHD stability of equilibria with high-confinement-mode pedestals and internal transport barriers (ITBs). Optimum density and temperature profiles were determined in the pedestal region based on EPED1 model, and the optimized profiles were utilized to investigate the preferable profiles in the core region. The MHD equilibrium calculations included bootstrap currents that were consistent with density and temperature profiles. Since a stabilizing effect by a perfectly conducting wall was not considered, stable equilibria found in this study require no feedback control of resistive wall modes. Effects of changing the aspect ratio on the ideal MHD stability properties were also examined. The ITB was found to have a preferable radial position, that realized both a higher volume-averaged beta and the decoupling of the instability in the core and pedestal regions, respectively. Moreover, it was found that the beta limit could be increased if the current density profile could be controlled so that a larger magnetic shear was realized in the ITB region. The pedestal height was better reduced from the marginally stable cases to avoid easy coupling with the driving force of instabilities in the core region. These properties were common for all aspect ratios examined. Moreover, the normalized beta limit under the no-wall condition was approximately 3 for the examined aspect ratios, which was higher than the target value 2.6 of the pulsed operations of JA DEMO 2014.journal articl