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We investigated the degradation of neutral beam (NB) fast-ion confinement depending on the NB power without magnetohydrodynamics instabilities in the Large Helical Device (LHD). In the LHD deuterium experiment, the neutron emission rate per NB power decreased by up to 20% with increasing injected NBs during a single discharge. Because there were no significant variations in the electron temperature and density, the NB shine-through rate, or the magnetic fluctuation due to the change in NB power, the reduction in the neutron emission rate indicates the degradation of the fast-ion confinement. In this paper, we formulated this degradation depending on the NB power and quantitatively estimated the degraded effective confinement time. In addition, we performed neutron emission rate simulations using the obtained effective confinement time. The simulation and experimental results were in good agreement, suggesting that the degraded effective confinement time is valid. [ABSTRACT FROM AUTHOR]

The trivalent terbium ion (Tb3+) emits ultra-stable visible light consisting of blue, green, yellow, and red. Tb-doped semiconductors are candidates for novel full-color light sources in next-generation displays. Particularly, Tb-doped AlxGa1−xN (AlxGa1−xN:Tb) has attracted much attention for device applications. We present the luminescence properties of AlxGa1−xN:Tb grown by the organometallic vapor phase epitaxy. At 15 K, emission related to the 5D4–7FJ (J = 3, 4, 5, 6) transitions is observed for AlxGa1−xN:Tb with x ≥ 0.03. Thermal quenching of emission originating from the 5D4–7FJ transition is suppressed for higher Al compositions, and the luminescence is clearly observed at room temperature for AlxGa1−xN:Tb with x ≥ 0.06. The small thermal quenching is attributed to the enhanced excitation to the 5D4 level of Tb3+ ions via the 4f–5d transition and not due to the suppression of energy back-transfer paths in excited Tb3+ ions. Although additional emission originating from the 5D3–7FJ transitions is observed at 15 K for AlxGa1−xN:Tb with x ≥ 0.15, it is not observed at room temperature because the excitation to the 5D3 level via the 4f–5d transition is less efficient at high temperature. For Al0.15Ga0.85N:Tb, monochromatic green light is demonstrated using a SiO2/ZrO2 distributed Bragg reflector. [ABSTRACT FROM AUTHOR]

We report on the fabrication and optical characteristics of microdisk (MD) resonators with Er,O-codoped GaAs (GaAs:Er,O) as an active component. MD resonators based on GaAs:Er,O with different sidewall angles are fabricated by electron beam lithography followed by two different processes: dry and wet etching. Numerical simulations using a finite-difference time-domain method demonstrate an increase in the cavity quality (Q) factor of the MDs when sharpening the taper angle of the MDs. Micro-photoluminescence characterization of the MD resonators with excitation by a He–Ne laser reveals an 11.4-fold enhancement of Er-related luminescence and a cavity Q factor of 4.2 × 103. For the MD resonators with tapered sidewalls, further enhancement of Er luminescence and increased Q factor (>9.0 × 103) are observed. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) light with a wavelength of 650–950 nm is used for various biomedical applications. Although NIR emitters are typically based on GaAs-related materials, they contain toxic elements, and the emission wavelength can easily shift during the device operation due to temperature changes and current injection levels. On the other hand, Tm 3 + , which is one of the rare-earth ions, can generate ultra-stable NIR luminescence with a wavelength of ∼ 800 nm , based on 3 H 4 – 3 H 6 transitions in a 4f shell, and we have recently focused on Tm-doped GaN (GaN:Tm) based light-emitting diodes (LEDs) as novel NIR emitters. In this paper, we present a demonstration of a NIR-LED based on GaN:Tm grown by the organometallic vapor phase epitaxy method with optimized growth conditions and structures, where the parasitic reaction is well suppressed. NIR luminescence from the GaN:Tm-based LED is derived from 3 H 4 – 3 H 6 transitions of Tm 3 + ions and consists of three dominant peaks at 795, 806, and 814 nm. The turn-on voltage of the NIR-LED is ∼ 6.9 V, and it is significantly lower than the previously reported electroluminescent devices based on GaN:Tm with impact ionization processes. From a current dependence of the electroluminescence spectra and temperature-dependent photoluminescence for the NIR-LED, the peak shifts are determined to be < 7.6 pm/mA and ∼ 1.3 pm/K, respectively. [ABSTRACT FROM AUTHOR]

The dopant distribution and surface and structural properties of Er- and Eu-doped GaN samples were investigated using atom probe tomography (APT) and atomic force microscopy (AFM). Erbium accumulation within host GaN threading dislocations was directly detected by APT allowing for the dislocations to be imaged in three dimensions. In addition, photoluminescence spectroscopy with high lateral resolution, by means of scanning near-field optical microscopy, was performed on Eu-doped GaN samples. By combining these results with AFM mappings of the same area, it was concluded that Eu3+ ions also accumulate at threading dislocations. Moreover, high-resolution surface profiles of both samples show that even dilute doping (<0.2%) of Eu and Er has a significant influence on the growth morphology of the GaN host material and the nature of the threading dislocations within it. Transmission electron microscopy techniques were used to show the influence of rare-earth incorporation on the growth of GaN lattice and the propagation of threading dislocations. [ABSTRACT FROM AUTHOR]

Background No easy-to-use fall risk assessment tools have been devised to assess occupational fall risk in older workers. Aims To develop an Occupational Fall Risk Assessment Tool (OFRAT) and report its predictive validity and reliability in older workers. Methods The baseline fall risk assessment was completed by 1113 participants aged ≥60 years who worked ≥4 days/month in Saitama, Japan. Participants were followed up for falls during occupational activities for 1 year, and 30 participants were assessed twice for test–retest reliability. The following assessment measures were summed to form the OFRAT risk score: older age, male sex, history of falls, physical work participation, diabetes, use of medications increasing fall risk, reduced vision, poor hearing, executive dysfunction and slow stepping. The scores were then classified into four grades (0–2 points: very low, 3 points: low, 4 points: moderate and ≥5 points: high). Results During follow-up, 112 participants fell 214 times during work. The negative binomial regression model showed that participants with higher grades had a higher incidence rate ratio [95% confidence interval] for falls than those with very low grades (low: 1.64 [1.08–2.47], moderate: 4.23 [2.82–6.34] and high: 6.12 [3.83–9.76]). The intraclass correlation coefficient for risk score was 0.86 [0.72–0.93], and the weighted kappa coefficient for grade assessment was 0.74 [0.52–0.95]. Conclusions The OFRAT is a valid and reliable tool for estimating the occupational fall risk in older workers. It may assist occupational physicians implement strategies to prevent falls in this group. [ABSTRACT FROM AUTHOR]

The compact neutron emission spectrometer (CNES) having a tangential sightline was installed to observe a significant Doppler shift of the neutron energy due to the high-energy tangential neutral beam (NB) injections in the Large Helical Device (LHD) for understanding of the energy distribution of fast-ion. The CNES is based on a 1-inch diameter and 1-inch height EJ301 liquid scintillator coupled with a conventional 1-inch photomultiplier tube. The histogram of the integrated pulse signal (Qtotal) during different NBs heating phases measured by the CNES shows that the edge of Qtotal changes depending on NB directions. Using the simple derivative unfolding technique, the neutron energy spectra were unfolded from the measured Qtotal histogram. Peaks of the neutron energy shift to 2.0 MeV, 2.42 MeV, and 3.0 MeV according to the injection direction of NBs. The obtained neutron energy is almost consistent with the virgin deuterium-deuterium neutron energy evaluated by the simple two-body kinematics considering the sightline of CNES, NB injection angle, and NB injection energy. [ABSTRACT FROM AUTHOR]

Studies of energetic particle transport due to energetic-particle-driven Alfvénic instability have progressed using neutron and energetic particle diagnostics in Large Helical Device deuterium plasmas. Alfvénic instability excited by injecting an intensive neutral beam was observed by a magnetic probe and a far-infrared laser interferometer. The interferometer showed Alfvénic instability composed of three modes that existed from the core to the edge of the plasma. A comparison between the observed frequency and shear Alfvén spectra suggested that the mode activity was most likely classified as an Alfvénic avalanche. A neutron fluctuation detector and a fast ion loss detector indicated that Alfvénic instability induced transport and loss of co-going transit energetic ions. The dependence of the drop rate of the neutron signal on the Alfvénic instability amplitude showed that significant transport occurred. Significant transport might be induced by the large amplitude and radially extended multiple modes, as well as a large deviation of the energetic ion orbit from the flux surface. [ABSTRACT FROM AUTHOR]

We report on the epitaxial growth and the optical properties of Tm,Yb-codoped ZnO (ZnO:Tm,Yb) thin films by sputtering-assisted metalorganic chemical vapor deposition. The characteristic light emission due to the intra-4f shell transitions of Tm3+ and Yb3+ ions in the ZnO host is observed at 4 K by using photoluminescence (PL) characterization. The time-resolved PL measurements on the Tm3+ and Yb3+ emission reveals that the carrier decay time of each ion can vary by changing the concentration of both Tm3+ and Yb3+ ions, which depends on a mixing ratio of Tm2O3 and Yb2O3 in a sputtering target. The energy transfer from Tm3+ to Yb3+ ions occurs in the sample with the high mixing ratio, and the reversed energy transfer process occurs with the lower mixing ratio. These results indicate that the concentration, and thus the carrier dynamics of Tm3+ and Yb3+ ions in the ZnO:Tm,Yb host, can be controlled by altering the mixing ratio of the sputter target and the frequency power. [ABSTRACT FROM AUTHOR]

We report on the growth and optical properties of Tm-doped AlGaN layers by organometallic vapor phase epitaxy (OMVPE). The morphological and optical properties of Tm-doped GaN (GaN:Tm) and Tm-doped AlGaN (AlGaN:Tm) were investigated by Nomarski differential interference contrast microscopy and photoluminescence (PL) characterization. Nomarski images reveal an increase of surface roughness upon doping Tm into both GaN and AlGaN layers. The PL characterization of GaN:Tm shows emission in the near-infrared range originating from intra-4f shell transitions of Tm3+ ions. In contrast, AlGaN:Tm also exhibits blue light emission from Tm3+ ions. In that case, the wider band gap of the AlGaN host allows energy transfer to higher states of the Tm3+ ions. With time-resolved PL measurements, we could distinguish three types of luminescent sites of Tm3+ in the AlGaN:Tm layer, having different decay times. Our results confirm that Tm ions can be doped into GaN and AlGaN by OMVPE, and show potential for the fabrication of novel high-color-purity blue light emitting diodes. [ABSTRACT FROM AUTHOR]

A systematic experimental study was performed on the Fano line shape exhibited by multilayer structures consisting of an Al layer, a SiO2 spacer layer, and an Al2O3 waveguide layer. In the structures studied, a sharp Fano resonance appears on the background of broad asymmetric resonance attributed to the excitation of a surface plasmon polariton at the Al/SiO2 interface. It is shown that the background asymmetric surface plasmon resonance can be well fitted to a single Fano function, and the sharp Fano line shape can be well fitted to a double Fano function expressed as a product of two single Fano functions. The results of measurements performed by varying the spacer layer thickness indicate that the width (Q factor) of the sharp Fano resonance decreases (increases) monotonously as the thickness increases. The Q factor achieved in the present study is as high as ~ 1500. A comparison with the results of electromagnetic calculations suggests that not only the spacer layer thickness but also the imaginary part of the dielectric constant of the waveguide layer plays an important role in the Fano line shape engineering. [ABSTRACT FROM AUTHOR]

We report on the formation and optical characteristics of Eu-doped GaN (GaN:Eu)/GaN core–shell nanowires (NWs) grown by organometallic vapor phase epitaxy. A moderate V/III ratio and growth temperature enable the incorporation of Eu3+ ions into the GaN shells on GaN core NWs, resulting in red luminescence at room temperature whose peak intensity is more than 20 times larger than for a GaN:Eu film on planar GaN. The cathodoluminescence characterization corroborates that the observed enhanced Eu luminescence originates from the predominant formation of highly efficient Eu centers in the sidewalls of the GaN:Eu/GaN core–shell NWs. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to (1) develop the physical fitness age, which is the biological age based on physical function, (2) evaluate the validity of the physical fitness age for the assessment of sarcopenia, and (3) examine the factors associated with the difference between physical fitness age and chronological age. Design: Cross-sectional study Setting and Participants: Community-dwelling older adults and outpatients. Measurements: A formula for calculating the physical fitness age was created based on the usual walking speed, handgrip strength, one-leg standing time, and chronological age of 4,076 older adults from the pooled data of community-dwelling and outpatients using the principal component analysis. For the validation of the physical fitness age, we also used pooled data from community-dwelling older adults (n = 1929) and outpatients (n = 473). Sarcopenia was diagnosed according to the Asian Working Group for Sarcopenia 2019 consensus. The association of D-age (the difference between physical and chronological ages) with cardiovascular risk factors, renal function, and cardiac function was examined. Results: The receiver operating characteristic analysis, with sarcopenia as the outcome, showed that the area under the curve (AUC) of physical fitness age was greater than that of chronological age (AUC 0.87 and 0.77, respectively, p < 0.001). Binomial logistic regression analysis revealed that the D-age was significantly associated with sarcopenia after adjustment for covariates (odds ratio 1.22, 95% confidence interval 1.19–1.26; p <0.001). In multivariate linear regression analysis with D-age as the dependent variable, D-age was independently associated with a history of diabetes mellitus (or hemoglobin A1c as a continuous variable), obesity, depression, and low serum albumin level. D-age was also correlated with estimated glomerular filtration rate derived from serum cystatin C, brain natriuretic peptide, and ankle-brachial index, reflecting some organ function and arteriosclerosis. Conclusions: Compared to chronological age, physical fitness age calculated from handgrip strength, one-leg standing time, and usual walking speed was a better scale for sarcopenia. D-age, which could be a simple indicator of physical function, was associated with modifiable factors, such as poor glycemic control, obesity, depressive symptoms, and malnutrition. [ABSTRACT FROM AUTHOR]

Memes within animated graphical interchange formats (GIFs) are developed and shared by Internet users to communicate cultural ideas, symbols, or practices for a wide global audience. Among the billions of GIFs shared internationally, some portray scientists engaged in scientific work. Media and science education scholarship alike have evidenced how scientists are portrayed can influence social perceptions of science and contribute to stereotypes that deter youth's interest in and affinity to science and science occupations. To understand what social perceptions of science may manifest from new media (GIFs), the present study ascertained stereotypes using Warmth and Competence constructs from Fiske's Stereotype Content Model (SCM). The SCM utilizes high, medium, and low warmth and competence dimensions found in media-based imagery to illuminate stereotypes. Researchers coded and categorised 287 meme-based GIFs of scientists sourced the largest online GIF repository, Giphy. A directed qualitative content analysis found high-competence and low-warmth dimensions most represented within the sample that theoretically (per SCM) represent perceptions that contribute to an envious stereotype with elements of admiration and contempt. This study suggests that although there have been improvements in the portrayals of scientists in media, however, GIFs may preserve and perpetuate the trope of the competent, yet cold, scientist. [ABSTRACT FROM AUTHOR]

The compact neutron emission spectrometer (CNES) having a tangential sightline was installed to observe a significant Doppler shift of the neutron energy due to the high-energy tangential neutral beam (NB) injections in the Large Helical Device (LHD) for understanding of the energy distribution of fast-ion. The CNES is based on a 1-inch diameter and 1-inch height EJ301 liquid scintillator coupled with a conventional 1-inch photomultiplier tube. The histogram of the integrated pulse signal (Qtotal) during different NBs heating phases measured by the CNES shows that the edge of Qtotal changes depending on NB directions. Using the simple derivative unfolding technique, the neutron energy spectra were unfolded from the measured Qtotal histogram. Peaks of the neutron energy shift to 2.0 MeV, 2.42 MeV, and 3.0 MeV according to the injection direction of NBs. The obtained neutron energy is almost consistent with the virgin deuterium-deuterium neutron energy evaluated by the simple two-body kinematics considering the sightline of CNES, NB injection angle, and NB injection energy. [ABSTRACT FROM AUTHOR]

K ¯ -nuclear bound systems, kaonic nuclei, have been widely discussed as products of the strongly attractive K ¯ N interaction in I = 0 channels. Recently, we demonstrated that kaonic nuclei can be produced via in-flight (K - , N) reactions using the low-momentum DC kaon beam at the J-PARC E15 experiment. We observed the simplest kaonic nuclei, K - p p , having a much deeper binding energy than normal nuclei. For further studies, we have proposed a series of experimental programs for the systematic investigation of light kaonic nuclei, from K ¯ N ( Λ (1405) ) to K ¯ N N N N . In the new experiment approved as J-PARC E80, we will measure the K ¯ N N N ( A = 3 ) system as a first step toward a comprehensive study. [ABSTRACT FROM AUTHOR]

Understanding energetic particle transport due to magnetohydrodynamic instabilities excited by energetic particles is essential to apprehend alpha particle confinement in a fusion burning plasma. In the large helical device (LHD), beam ion and deuterium–deuterium fusion-born triton transport due to resistive interchange mode destabilized by helically-trapped energetic ions (EIC) are studied employing comprehensive neutron diagnostics, such as the neutron flux monitor and a newly developed scintillating fiber detector characterized by high detection efficiency. Beam ion transport due to EIC is studied in deuterium plasmas with full deuterium or hydrogen/deuterium beam injections. The total neutron emission rate (Sn) measurement indicates that EIC induces about a 6% loss of passing transit beam ions and a 60% loss of helically-trapped ions. The loss rate of helically-trapped ions, which drive EIC, is larger than the loss rate of passing transit beam ions. Furthermore, the drop of Sn increasing linearly with the EIC amplitude shows that barely confined beam ions existing near the confinement-loss boundary are lost due to EIC. In full deuterium conditions, a study of deuterium–deuterium fusion-born triton transport due to EIC is performed by time-resolved measurement of total secondary deuterium–tritium neutron emission rate (Sn_DT). Drop of Sn_DT increases substantially with EIC amplitude to the third power and reaches up to 30%. The relation shows that not only tritons confined in confined-loss boundary, but also tritons confined in the inner region of a plasma, are substantially transported. [ABSTRACT FROM AUTHOR]

Background: Use of neoadjuvant therapy for elderly patients with pancreatic cancer has been debatable. With FOLFIRINOX (folinic acid, 5-fluorouracil, irinotecan, oxaliplatin) or gemcitabine plus nab-paclitaxel (GnP) showing tremendous effects in improving the overall survival of patients with borderline resectable and locally advanced pancreatic cancer, there is no definitive consensus regarding the use of this regimen in the elderly. Methods: This study evaluated the eligibility of elderly patients with borderline resectable or locally advanced pancreatic cancer for neoadjuvant therapy. Patients registered in the database of pancreatic cancer at the University of Colorado Cancer Center, who underwent neoadjuvant treatment between January 2011 and March 2019, were separated into three age groups (less than 70, 70-74, 75 or more years) and respective treatment outcomes were compared. Results: The study included 246 patients with pancreatic cancer who underwent neoadjuvant treatment, of whom 154 and 71 received chemotherapy with FOLFIRINOX and GnP respectively. Among these 225 patients, 155 were younger than 70 years, 36 were aged 70-74 years, and 34 were aged 75 years or older. Patients under 70 years old received FOLFIRINOX most frequently (124 of 155 versus 18 of 36 aged 70-74 years, and 12 of 34 aged 75 years or more; P<0.001). Resectability was similar among the three groups (60.0, 58.3, and 55.9 per cent respectively; P=0.919). Trends towards shorter survival were observed in the elderly (median overall survival time 23.6, 18.0, and 17.6 months for patients aged less than 70, 70-74, and 75 or more years respectively; P=0.090). After adjusting for co-variables, age was not a significant predictive factor. Conclusion: The safety and efficacy of multiagent chemotherapy in patients aged 75 years or over were similar to those in younger patients. Modern multiagent regimens could be a safe and viable treatment option for clinically fit patients aged at least 75 years. [ABSTRACT FROM AUTHOR]

The excellent soft magnetic properties of amorphous (a-) CoFeSiB films make it suited for use in the yoke of granular-in-gap sensors, but only if their thermal stability can be improved. To this end, this study investigated the effects of adding small amounts of other metals on the magnetic and structural properties of a-CoFeSiB films. It was found that adding metals with relatively large atomic radii is an effective way to increase thermal stability, with both Ta and Hf showing good thermal stability after annealing at temperatures of 473 to 573 K. Indeed, a -(CoFeSiB)96.2Hf3.8 film was found to maintain its initial coercivity of 0.2 Oe without very little decrease in magnetization after annealing at 623 K. Furthermore, even after annealing at 673K a -(CoFeSiB)93.0Hf7.0 film still had a relatively low coercivity of approximately 0.5 Oe. [ABSTRACT FROM AUTHOR]

We report on the growth and optical characteristics of Eu-doped ZnO (ZnO:Eu) films on ZnO nanowires (NWs) by sputtering-assisted metalorganic chemical vapor deposition. ZnO:Eu films are grown by sputtering Eu2O3 targets during the growth of ZnO NWs. The crystal quality of ZnO host materials is improved by using the NW configuration due to a strain relaxation effect, which is elucidated by optical characterization. An enhancement of Eu3+ luminescence at 613 nm is observed at room temperature for the ZnO:Eu/ZnO NWs as compared to a conventional film. Site-selective spectroscopy by direct excitation of Eu3+ ions by a tunable dye laser reveals that the most intense emission peak is located at a wavelength of ∼613.5 nm, which coincides with the main peak under indirect excitation. This result indicates that the observed enhanced Eu luminescence is due to a relative increase in the number of Eu centers which can effectively be excited via the host material. [ABSTRACT FROM AUTHOR]

The neutron emission profile of deuterium plasma in the Large Helical Device was measured with a multi-sightline vertical neutron camera under various magnetic field strength conditions. It was found that the line-integrated neutron emission profile shifts outward in the co-neutral beam (NB) case and inward in the counter NB case. Here, co- and counter directions correspond to enhance and reduce the poloidal magnetic field directions, respectively. The shift becomes more significant when the magnetic field decreased in strength. The experimentally obtained neutron emission profile was compared with the orbit-following models simulated through the DELTA5D code. The calculated neutron emission profiles vary according to the magnetic field strength because of the change of beam ion orbit and the slowing down due to the plasma parameter changes. Although a relatively narrow profile was obtained in the calculations at the inboard side for the co-NB case in the relatively low field condition, the profiles obtained through calculation and experiment were almost qualitatively aligned. [ABSTRACT FROM AUTHOR]

Characteristics of plasma parameters and turbulence in the isotope-mixing and the non-mixing states in hydrogen-deuterium mixture plasmas in the large helical device are discussed. The isotope mixing state is characterized by the uniform isotope ratio profile regardless of the location of the particle source of each species in the isotope mixture plasma. The isotope non-mixing state is identified by the non-uniform isotope ratio profile measured with bulk charge exchange spectroscopy when the beam fueling isotope species differs from the recycling isotope species. The effect of collisionality, ratio, sign of density gradient on transition between isotope mixing and non-mixing is discussed. The plasma parameters preferable for the non-mixing state are found to be lower collisionality, higher , and negative or zero density gradient (peaked or flat density profile). The time scale of transition from non-mixing to mixing is evaluated by the hydrogen and deuterium pellet injection near the plasma edge and is found to be less than 5 ms, which is much shorter than the particle confinement time. The strong correlation between isotope mixing and turbulence characteristics is observed. This strong correlation suggests the change in turbulence is a strong candidate for the mechanism causing the transition between uniform and non-uniform isotope density ratio profiles. [ABSTRACT FROM AUTHOR]

We found an anomalous Eu-related luminescence peak in the temperature dependence of photoluminescence (PL) spectra in Eu-doped gallium nitride (GaN:Eu) grown by organometallic vapor phase epitaxy. Its PL intensity increased with increasing temperature and reached a maximum around 140 K, while the main peak intensities decreased monotonically in this region. Timeresolved PL measurements (TR-PL) revealed a delayed increase of PL intensity after the laser pulse. An analysis of the characteristics hereof indicated that the mechanism behind this afterglow is thermally activated and its transfer efficiency is dependent on the excitation intensity. We developed a model that explains these results, where excitation of the Eu ions associated to this peak takes place via two different carrier traps. [ABSTRACT FROM AUTHOR]

The nature of Eu incorporation and resulting luminescence efficiency in GaN has been extensively investigated. By performing a comparative study on GaN:Eu samples grown under a variety of controlled conditions, and using a variety of experimental techniques, the configuration of the majority site has been concluded to contain a nitrogen vacancy (VN). The nitrogen vacancy can appear in two symmetries, which has a profound impact on the luminescence and magnetic properties of the sample. The structure of the minority site has also been identified. We propose that, for both sites, the excitation efficiency of the red Eu emission is improved by the presence of donor-acceptor pairs in the close vicinity of the Eu. [ABSTRACT FROM AUTHOR]

Er-concentration effect in GaAs;Er,O containing charge carriers (n-type, high resistance, p-type) has been studied by X-band Electron spin resonance (ESR) at low temperature (4.7K

A diamond-based neutral particle analyzer (DNPA) array composed of single-crystal chemical vapor deposition (sCVD) diamond detectors was installed on the Large Helical Device (LHD) for measuring the helically trapped energetic particles. In high neutron flux experiments, the unwanted neutron-induced pulse counting rate should be estimated using the neutron diagnostics because a diamond detector is sensitive to neutrons as well as energetic neutral particles. In order to evaluate the quantitative neutron-induced pulse counting rate on the DNPA, the response functions of the sCVD diamond detector for mono-energetic neutrons were obtained using accelerator-based D–D and D–7Li neutron sources in Fast Neutron Laboratory (FNL). As a result of the neutron flux estimation by the Monte Carlo N-Particle code at the NPA position in the LHD and the response function obtained in the FNL experiment, the counting rate of the neutron-induced signal was predicted to be 1.1 kcps for the source neutron emission rate of Sn = 1 × 1015 n/s. In the LHD experiment, the neutron-induced signals were observed by closing the gate valve during the plasma discharges. It is found that the counting rates of the neutron-induced signals proportional to Sn reached 1.1 kcps at Sn = 1 × 1015 n/s. As a result of the quantitative estimation of the neutron-induced signals on the DNPA using other neutron measurements, it has become possible to accurately measure energetic neutral particles in the high neutron flux experiment. [ABSTRACT FROM AUTHOR]

In this work, energetic-ion confinement and loss due to energetic-ion driven magnetohydrodynamic modes are studied using comprehensive neutron diagnostics and orbit-following numerical simulations for the Large Helical Device (LHD). The neutron flux monitor is employed in order to obtain global confinement of energetic ions and two installed vertical neutron cameras (VNCs) viewing different poloidal cross-sections are utilized in order to measure the radial profile of energetic ions. A strong helically-trapped energetic-ion-driven resistive interchange mode (EIC) excited in relatively low-density plasma terminated high-temperature state in LHD. Changes in the neutron emission profile due to the EIC excitation are clearly visualized by the VNCs. The reduction in the neutron signal for the helical ripple valley increases with EIC amplitude, which reaches approximately 50%. In addition to the EIC experiment, orbit-following simulations using the DELTA5D code with EIC fluctuations were performed to assess the energetic-ion transport and loss. Two-dimensional temporal evolution results show that the neutron emissivity at the helical ripple decreases significantly due to the EIC. The rapid reduction in neutron emissivity shows that the helically-trapped beam ions immediately escape from the plasma. The reduction in the VNC signals for the helical ripple valley and the total neutron emission rate increase with increasing EIC amplitude, as observed in the experiment. Calculated line-integrated neutron emission results show that the profile measured by VNC1 has one peak, whereas the profile measured by VNC2 has two peaks, as observed in the experiment. Although the neutron emission profile for VNC2 has a relatively wide peak compared with the experimental results, the significant decrease in neutron signal corresponding to the helical ripple valley was successfully reproduced. [ABSTRACT FROM AUTHOR]

For understanding the physics of energetic particles, the deuterium experimental campaigns started in Large Helical Device (LHD) from March 2017. To investigate the behavior of energetic particles, a Fast-ion D Alpha (FIDA) diagnostic was installed on the LHD. In the FIDA diagnostic, the Doppler-shifted D alpha light from fast-neutrals are utilized as signals of energetic particles, where these fast-neutrals are produced by the charge exchange process between fast-ions in the plasma and actively injected neutrals by neutral beam (NB). The advantages of the FIDA diagnostic are the velocity and the spatially resolved measurement of fast-ions at the crossing point between its line of sight (LOS) and the incident line of NB. The most recent FIDASIM is enhanced to simulate signals produced in three-dimensional magnetic configurations. The new version of FIDASIM uses the fast-ion distribution function produced by GNET as input to simulate FIDA signals at LHD. In order to validate the new version of the code, measurements of radial profiles of fast-ions using the FIDA diagnostic are performed in magnetohydrodynamic (MHD)-quiescent plasmas. The measured spectra are in good agreement with the theoretical prediction by 3D-supporting FIDASIM at the center of the plasma (R= 3.5 m∼3.7 m, reff/a99= −0.28∼0.05) on the LHD when the line averaged electron density is ne_avg < 1.23 × 1019 m−3. On the other hand, the measured spectra are in disagreement with the theoretical prediction by 3D-supporting FIDASIM at even the center of the plasma when the line averaged electron density is ne_avg ≥ 1.23 × 1019 m−3. [ABSTRACT FROM AUTHOR]

Toroidal Alfvén eigenmode (TAE) bursts are often observed in relatively low-magnetic-field experiments in the Large Helical Device (LHD) with tangential nuclear beam injection. During TAE bursts, hole-clump pairs in real space were observed in previous studies. In order to observe the behavior of the energetic particles during TAE bursts in more detail, a tangential E-parallel-B-type neutral particle analyzer (E||B-NPA) was upgraded to improve the time resolution up to 100 kilo samples per second by updating its measurement electronic circuits. Using this high time resolution E||B-NPA, the clump formations are clearly observed in real space. In order to analyze the observed particles with high time resolution, the conditional averaging technique is used. The lost energetic particles with 150 keV were initially observed just before the TAE burst, and the energy decreases faster than the classical slowing down time. The energetic particles transported by the TAE burst were detected with energy slowing down time of 6–8 ms for more than 6 ms after the TAE burst had finished. According to the orbit trace code Lorentz orbit (LORBIT) calculation, the particle pitch angle and radial location (ρ = r/a99) of the energetic particles resonating with the TAE mode frequency are increased by 5° and 0.2, respectively, during TAE bursts. These results are consistent with the observed downward frequency chirping of the magnetic fluctuation. By comparing the energy of the detected particles by E||B-NPA and the corresponding frequency of the magnetic fluctuation, the pitch angles of the resonant particles are considered to be 15°–25° at 150 keV before they are transported by the TAE burst. The frequency chirping of the magnetic fluctuation shows good agreement with the observed clump structure by considering the pitch angle of the resonant particles. [ABSTRACT FROM AUTHOR]

FIDASIM is a code that models signals produced by charge-exchange reactions between neutrals and ions (both fast and thermal) in magnetically confined plasmas. With the ion distribution function as input, the code predicts the efflux to a neutral particle analyzer diagnostic and the photon radiance of Balmer-alpha light to a fast-ion D diagnostic, in addition to many other related quantities. A new, parallelized version of the Monte Carlo code FIDASIM has been developed in Fortran90 that is substantially faster than the original interactive data language version. Modified algorithms include more accurate treatments of the time dependent collisional-radiative equations that describe neutral energy levels, of the cloud of 'halo' neutrals that surround the injected neutral beam, and of finite Larmor radius effects. Enhanced physics capabilities include modelling 'passive' signals from cold edge neutrals, the ability to treat general three-dimensional magnetic confinement configurations, and calculations of diagnostic-specific weight functions that enable tomographic reconstructions of the fast-ion distribution function. Neutral beam attenuation, beam emission, and fast-ion birth profiles are also modelled. The new algorithms have been successfully validated against experimental data and new features have been tested through benchmarks between two independently developed versions of the code. [ABSTRACT FROM AUTHOR]

Two new vertical neutron cameras characterized by high detection efficiency were developed on the Large Helical Device in order to observe poloidal structures of helically trapped beam ions created by the perpendicularly injected positive-ion based neutral beam (P-NB) and are newly operated since 2018. In this work, the neutron fields at the vertical neutron cameras are investigated using the Monte Carlo N-particle transport code to evaluate the performance of its collimators. The results indicate that neutrons are attenuated by the heavy concrete and are well collimated through the collimator to detectors. Neutron spectra at the detector position show over 99% of uncollided 2.45 MeV neutrons. Time evolution of neutron emission profiles during the short pulse of P-NB injection is measured by the vertical neutron cameras. Peaks on the neutron emission profiles corresponding to the helically trapped beam ion are successfully obtained, as designed. The decrease in line integrated neutron flux at the peak positions after the P-NB stops is consistent with the behavior of the total neutron emission rate measured by the neutron flux monitor. [ABSTRACT FROM AUTHOR]

The neutral beam (NB) fast ion confinement in the Large Helical Device (LHD) is studied for several full field ($B_{t}\sim 2.75~\text{T}$) magnetic configurations by a combination of neutron measurement and simulations. To investigate the NB fast ion confinement, we have performed a series of short-pulse NB injection experiments. The experiment results are analysed by the integrated code TASK3D-a. From this investigation, the effective particle diffusion coefficients of the tangential and perpendicular NBs are approximately $D^{\text{eff}}\sim 0.1~\text{m}^{2}~\text{s}^{-1}$ and $D^{\text{eff}}\sim 1~\text{m}^{2}~\text{s}^{-1}$ in the standard configuration. It is clarified that the NB fast ion confinement improves when the plasmas are shifted inward. Moreover, it is also found that the simulation, which considers the deuteron dilution effect due to the presence of impurity ions, can describe a neutron emission rate consistent with the measurement. [ABSTRACT FROM AUTHOR]

We evaluate the enhancement of Er luminescence coupled to two-dimensional (2D) photonic crystal (PC) nanocavities by means of photoluminescence measurements and numerical simulations. L3 PC nanocavities are utilized for characterization and evaluation, with GaAs:Er,O grown by low-pressure organometallic vapor phase epitaxy as the active layer. Optical characterization at room temperature demonstrates a 5.8-fold enhancement of Er luminescence due to coupling to the cavity mode of the 2D-PC nanocavities. This enhancement of Er luminescence is supported by a finite-difference time domain simulation where an enhancement of 4.1 times is found, which is in reasonable agreement with the observed experimental results. These results pave the way toward understanding the interaction between cavity modes in PC nanocavities and luminescence from rare-earth elements. [ABSTRACT FROM AUTHOR]

Simultaneous measurement of negative ion source plasma and extracted beam is carried out in order to clarify a key plasma parameter governing the meniscus formation in negative ion sources for fusion. The plasma discharge is performed with various discharge powers at different bias voltages in order to vary the plasma parameters. It is shown that the beam width changes along the same curve with respect to the negative ion density at any bias voltage while it varies along different curves with other plasma parameters depending on the bias voltage. This implies that the mechanism of meniscus formation in negative ion sources could be described along the similar manner as positive ion sources. [ABSTRACT FROM AUTHOR]

Density distributions of negative hydrogen (H−) ions and negative deuterium (D−) ions were measured with the laser photodetachment method in the extraction region of the negative ion source. The distribution of H− ion density peaks at the center of the ion source, while that of the D− ion shows a flatter profile in the direction parallel to the plasma grid. The positive ion densities of hydrogen and deuterium estimated from the positive saturation current indicate similar profiles with different amounts close to the grid. The difference in the H− ion and D− ion distributions can be explained by the difference in the negative ion yield and the survival probability of the ions due to the isotope effect. [ABSTRACT FROM AUTHOR]

Second deuterium operation of the negative ion based neutral beam injector was performed in 2018 in the large helical device. The electron and ion current ratio improves to Ie/Iacc(D) = 0.31 using the short extraction gap distance of 7 mm between the plasma grid (PG) and the extraction grid (EG). The strength of the magnetic field by the electron deflection magnet installed in the EG increases by 17% at the PG ingress surface, which effectively reduces the electron component in the negative ion rich plasma in the vicinity of PG apertures. The reduction of the electron current made it possible to operate at a high power arc discharge and beam extraction. Then, the deuterium negative ion current increases to 55.4 A with the averaged current density of 233 A/m2. The thermal load on the EG using 7 mm gap distance is 0.6 times smaller than the thermal load using a 8 mm gap caused by the reduction of coextracted electron current. The injection beam power increases to 2.9 MW in the beam line BL3, and the total beam injection power increases to 7 MW by three beam lines in the second deuterium campaign. [ABSTRACT FROM AUTHOR]

(001)-oriented Ni80Fe20/Mn100-xPtx and Co90Fe10/Mn100-xPtx epitaxial bilayers were prepared using the molecular beam epitaxy method. Their exchange anisotropies were measured using a torque magnetometer, while their interfacial Mn uncompensated moments were measured by means of x-ray magnetic circular dichroism. The bilayers exhibited both one- and fourfold components in their anisotropy torque curves, which are difficult to explain using a simple model assuming the coherent rotation of ferromagnetic (F) and antiferromagnetic (AF) spins. Uncompensated Mn moments were confirmed to exist in the Mn100-xPtx layer due to exchange coupling with the adjacent F layer, and the Mn moment of CoFe/Mn100-xPtx was found to be larger than that of NiFe/Mn100-xPtx. In order to understand the experimental results, we extended the Mauri et al. [J. Appl. Phys. 62, 3047 (1987)] domain wall model by assuming cubic anisotropy in the AF and four AF domains whose interfacial moments are oriented along the principal axis of (001)-oriented Mn–Pt. The model predicted the uncompensated AF moment resulting from the domain wall formed in the AF layer and well reproduced the coexistence of one- and fourfold anisotropies in the in-plane torque curves. The uncompensated moment and torque curve were found to be dependent on the ratio of F/AF interfacial exchange coupling and the AF domain wall energy. By changing the ratio, it was possible to reproduce exchange anisotropy for various systems, such as NiFe/MnPt, NiFe/MnIr, and CoFe/MnPt. [ABSTRACT FROM AUTHOR]

A bulk charge exchange spectroscopy system has been applied to measure the radial profiles of the hydrogen (H) and deuterium (D) density ratio in the isotope mixture plasma in a large helical device. Charge exchange lines of Hα and Dα are fitted by 4 Gaussian of H and D cold components and H and D hot components with 5 parameters by combining the measurement of plasma toroidal rotation velocity with carbon charge exchange spectroscopy. The radial profiles of the relative density of hydrogen and deuterium ions are derived from H and D hot components measured and the beam density calculated from beam attenuation calculation. A proof-of-principle experiment is performed by the H pellet and the D pellet injections into the H-D mixture plasma. [ABSTRACT FROM AUTHOR]

We have recently developed a technique to synthesize endohedral fullerenes that involves the collision of vaporized fullerenes and plasma particles produced following the laser ablation of a solid material. Using this technique, we synthesized N@C60 using a boron nitride rod as the source of the plasma particles. Optical emission measurements showed that the kinetic energy of N+ ions could be controlled from 20 to 65 eV by changing the energy of the incident laser beam. The synthesis of N@C60 was performed with a N+ kinetic energy of 65 eV, a C60 vaporizing temperature of 800 °C, and a total reaction time of one hour. By optimizing the kinetic energy for producing the encapsulated particles, we were able to synthesis N@C60 with a purity of 4.52 x 10−3%. The purity of our material was two orders of magnitude higher than that achieved using alternative physical synthetic methods that use solid materials, such as arc discharge and co-evaporation methods. [ABSTRACT FROM AUTHOR]

Negative-ion neutral-beam injection (NNBI) is an important source of heating and current drive for next-step fusion devices where the injected energy can range from hundreds of keV to 1 MeV. Few diagnostics are suitable for phase-space resolved measurements of fast ions with energy in excess of 100 keV. A study to assess the feasibility of fast-ion deuterium-alpha (FIDA) spectroscopy to diagnose high-energy ions produced by NNBI is presented. Case studies with the Large Helical Device (LHD) and JT-60SA illustrate possible solutions for the measurement. The distribution function of fast ions produced by NNBI is calculated for both devices, and the FIDA spectrum is predicted by synthetic diagnostic simulation. Results with 180 keV NNBI in LHD show that, with a judicious choice of viewing geometry, the FIDA intensity is comparable to that obtained with the existing FIDA system. The measurement is more challenging with the 500 keV NNBI in JT-60SA. Simulations predict the FIDA intensity to be about 1% of the background bremsstrahlung, which is small compared to existing FIDA implementations with positive neutral-beam injection where signal levels are an order of magnitude larger. The sampling time required to extract the small FIDA signal is determined using a probabilistic approach. Results indicate that long averaging periods, from ones to tens of seconds, are needed to resolve the FIDA signal in JT-60SA. These long averaging times are suitable in long-pulse (∼100 s), steady-state devices like JT-60SA where an important measurement objective is the spatial profile of the slowing-down distribution of fast ions. [ABSTRACT FROM AUTHOR]

To evaluate negative ion beam properties, a dual beamlet monitor system has been developed. The dual beamlet monitor system has two diagnostics in one hexagonal box. One diagnostic is a "fast beamlet monitor" for measuring the time evolution of beamlet current profiles with the time resolution of up to 25 MHz. The other diagnostic is a "pepper-pot-type phase space analyzer," which is applied for the evaluation of a phase space structure of the negative ion beamlet. The dual beamlet monitor system is applied to the measurement of the beamlet in the Neutral Beam Test Stand at National Institute for Fusion Science (NIFS-NBTS), in which the beam accelerator is almost identical to those of working beam injectors in the large helical device. It is demonstrated that the overlapping components from the neighboring beamlet can be eliminated, and the phase space structure can be obtained for the single beamlet. [ABSTRACT FROM AUTHOR]

Summary: Clinicians' evaluations of older adults sometimes reveal inconsistencies between objective and subjective dental status. This study investigated which factors contribute both to good objective masticatory function (OMF) and the poor subjective masticatory function (SMF) that often becomes a clinical issue. Study participants included 635 elderly community‐dwelling Japanese adults who underwent a comprehensive geriatric health examination in 2012. SMF was assessed with a question from the Kihon Checklist on eating difficulties (poor or good). OMF was assessed by a colour‐changing gum (poor or good). Also investigated were age, sex, depressive symptoms, instrumental activities of daily living (I‐ADLs), number of people who joined the participant at dinner, grip strength, usual walking speed, number of remaining teeth, number of functional teeth and their occlusal force. The group with good OMF and good SMF, defined as group 1, and the group with good OMF but poor SMF, group 2, were compared. Logistic regression analyses confirmed that the number of remaining and functional teeth participants had was statistically unrelated to differences between OMF and SMF. Instead, differences were related to stronger depressive symptoms (OR = 1.67, CI = 1.14‐2.44), less ability to conduct I‐ADL activities (OR = 0.73, CI = 0.59‐0.91), slower usual walking speeds (OR = 0.18, CI = 0.06‐0.58) and less occlusal force (OR = 0.99, CI = 0.99‐1.00). Depressive symptoms, I‐ADLs, and physical function are shown to be significantly related to divergence between objective and subjective masticatory function in elderly Japanese. This suggests that dissociations between objective and subjective dental evaluations of elderly adults indicate need for assessment of their mental and physical function. [ABSTRACT FROM AUTHOR]