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result(s) for
"Murata Koichi"
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Emotional valence sensing using a wearable facial EMG device
2021
Emotion sensing using physiological signals in real-life situations can be practically valuable. Previous studies have developed wearable devices that record autonomic nervous system activity, which reflects emotional arousal. However, no study determined whether emotional valence can be assessed using wearable devices. To this end, we developed a wearable device to record facial electromyography (EMG) from the corrugator supercilii (CS) and zygomatic major (ZM) muscles. To validate the device, in Experiment 1, we used a traditional wired device and our wearable device, to record participants’ facial EMG while they were viewing emotional films. Participants viewed the films again and continuously rated their recalled subjective valence during the first viewing. The facial EMG signals recorded using both wired and wearable devices showed that CS and ZM activities were, respectively, negatively and positively correlated with continuous valence ratings. In Experiment 2, we used the wearable device to record participants’ facial EMG while they were playing Wii Bowling games and assessed their cued-recall continuous valence ratings. CS and ZM activities were correlated negatively and positively, respectively, with continuous valence ratings. These data suggest the possibility that facial EMG signals recorded by a wearable device can be used to assess subjective emotional valence in future naturalistic studies.
Journal Article
Metal-to-insulator switching in quantum anomalous Hall states
2015
After decades of searching for the dissipationless transport in the absence of any external magnetic field, quantum anomalous Hall effect (QAHE) was recently achieved in magnetic topological insulator films. However, the universal phase diagram of QAHE and its relation with quantum Hall effect (QHE) remain to be investigated. Here, we report the experimental observation of the giant longitudinal resistance peak and zero Hall conductance plateau at the coercive field in the six quintuple-layer (Cr
0.12
Bi
0.26
Sb
0.62
)
2
Te
3
film, and demonstrate the metal-to-insulator switching between two opposite QAHE plateau states up to 0.3 K. Moreover, the universal QAHE phase diagram is confirmed through the angle-dependent measurements. Our results address that the quantum phase transitions in both QAHE and QHE regimes are in the same universality class, yet the microscopic details are different. In addition, the realization of the QAHE insulating state unveils new ways to explore quantum phase-related physics and applications.
The quantum anomalous Hall effect is a recently demonstrated chiral transport phenomenon arising in magnetically doped topological insulators. Here, the authors study the Hall plateau switching and universal phase diagram of the quantum anomalous Hall effect in thin films of two-dimensional Cr-doped (BiSb)
2
Te
3
.
Journal Article
Electric-field control of spin–orbit torque in a magnetically doped topological insulator
2016
Electric-field manipulation of magnetic order has proved of both fundamental and technological importance in spintronic devices. So far, electric-field control of ferromagnetism, magnetization and magnetic anisotropy has been explored in various magnetic materials, but the efficient electric-field control of spin–orbit torque (SOT) still remains elusive. Here, we report the effective electric-field control of a giant SOT in a Cr-doped topological insulator (TI) thin film using a top-gate field-effect transistor structure. The SOT strength can be modulated by a factor of four within the accessible gate voltage range, and it shows strong correlation with the spin-polarized surface current in the film. Furthermore, we demonstrate the magnetization switching by scanning gate voltage with constant current and in-plane magnetic field applied in the film. The effective electric-field control of SOT and the giant spin-torque efficiency in Cr-doped TI may lead to the development of energy-efficient gate-controlled spin-torque devices compatible with modern field-effect semiconductor technologies.
Electric field control of spin–orbit torque and magnetization switching can be achieved in a Cr-doped topological insulator thin film incorporated in a field-effect transistor structure, promising gate-controlled spintronic applications.
Journal Article
Estimating Vertical Movement and Slip Distribution During the 2018 Boso, Japan, Slow Slip Event From Ocean Bottom Pressure Gauge Data and an Oceanic Model
by
Sato, Toshinori
,
Shinohara, Masanao
,
Shibata, Saki
in
Bottom pressure
,
Components
,
Crustal movement
2024
Many slow slip events (SSEs) occur beneath the ocean, and continuous ocean‐bottom pressure gauge (OBP) observations provide useful data. OBPs record both oceanic variations and crustal movements, so we developed a multi‐channel singular spectrum analysis method to remove oceanic variations and applied our method to OBPs and oceanic model data. Then components of the oceanic model with good correlations to the OBP data were subtracted from the observed data. This method compensates for the incompleteness of the oceanic model and removes oceanic variations better than use of the original model. We applied the method to OBP data for the 2018 Boso, Japan, SSE to estimate its slip distribution. Comparing slip distributions obtained with and without the OBP data, we found that the distribution obtained using OBP data extended further offshore, and the offshore estimation error was smaller. Our study shows that offshore observations using OBPs are important for characterizing SSEs. Plain Language Summary Slow slip events (SSEs) occur when faults slip slowly without generating seismic waves. Because most SSEs occur under the ocean, continuous observations by ocean‐bottom pressure instruments (OBPs) provide useful data. OBPs record both oceanic changes and seafloor movements. To remove the oceanic changes and more clearly observe seafloor movements, we developed a signal processing method to extract similar components from multiple time series. We applied our method to OBP data and oceanic model data, then subtracted the components of the oceanic model that match the OBP data from the observed data. This method removed the oceanic changes from the OBP data better than use of the original oceanic model alone. We applied this method to OBP data for the 2018 Boso, Japan, SSE and used vertical motions in the OBP data to estimate the slip distribution. The distribution obtained with the OBP data extended further offshore and was more accurate than that obtained without the OBP data. This study shows that observations of the ocean bottom obtained with OBPs are important for characterizing SSEs. Key Points We removed oceanic variations from ocean‐bottom pressure data using a reconstructed oceanic model, achieving ±4 mm observed accuracy The reconstructed oceanic model includes only components with good correlations between observed data and the oceanic model Use of the ocean‐bottom pressure data and the proposed method improved the accuracy of the slow slip distribution in offshore areas
Journal Article
Minimally invasive LLIF surgery to decrease the occurrence of adjacent-segment disease compared to conventional open TLIF
by
Fujibayashi, Shunsuke
,
Matsuda, Shuichi
,
Murata, Koichi
in
Back pain
,
Back surgery
,
Bone implants
2023
PurposeLateral lumbar interbody fusion with percutaneous pedicle screw fixation (Mis-LLIF) can establish indirect decompression by lifting the vertebra with a large intervertebral cage, which causes less damage to the posterior elements. Thus, Mis-LLIF is expected to reduce the incidence of adjacent segment disease (ASD). The aim of the study was to compare the occurrence of ASD between Mis-LLIF and conventional open transforaminal interbody fusion (TLIF).MethodsA total of 156 patients (TLIF group = 88, Mis-LLIF group = 68) who underwent single-level lumbar interbody fusion (L2/3, L3/4, or L4/5) at a single institution between 2003 and 2018 with minimum 2-year follow-up were retrospectively reviewed. The incidence of symptomatic ASD requiring reoperation (S-ASD) and radiological adjacent segment degeneration (R-ASD) 2 years postoperatively were investigated between 51 paired patients from both groups who were propensity score (PS) matched by demographic and baseline clinical data. The effect of characteristics arising from differences in surgical methods between Mis-LLIF and TLIF, such as the amount of distraction of the index fused level (∆H), on S-ASD and R-ASD was also examined.ResultsThere were no significant differences in the incidence of S-ASD between the Mis-LLIF and TLIF groups (adjusted OR 1.3; 95% CI 0.41–3.9). There was no significant difference in the incidence of R-ASD between the Mis-LLIF and TLIF groups both at the cranial (adjusted OR 1.0; 95% CI 0.22–4.5) and caudal level (adjusted OR 1.5; 95% CI 0.44–5.3). On the other hand, ∆H was significantly higher in the Mis-LLIF group than in the TLIF group (3.6 mm vs. 1.7 mm, respectively, P < 0.0001), and was extracted as a significant independent risk factor for S-ASD (adjusted HR 2.7; 95% CI 1.1–6.3) and R-ASD at the cranial side (adjusted HR 6.4; 95% CI 1.7–24) in multivariable analysis with PS adjustment.ConclusionsThe incidence of R-ASD or S-ASD was not significantly reduced in the Mis-LLIF group compared to the TLIF group, with greater ∆H potentially being a contributing factor. Using a thin cage in both TLIF and Mis-LLIF may decrease the occurrence of ASD.
Journal Article
Analyzing Environmental Continuous Improvement for Sustainable Supply Chain Management: Focusing on Its Performance and Information Disclosure
2016
This study analyzes the relationship between the implementation and information disclosure of environmental continuous improvement (e-CI) in sustainable supply chain management. The analyzed data relates to e-CI delivered from 19 manufacturing industry types in Japan. A degenerated Charnes-Cooper-Rhodes model, a proposed model for data envelopment analysis, is also used for the analysis. The obtained result is a classification of types of manufacturing industries from the perspective of their capabilities in both e-CI implementation and information disclosure to systematically discover emphatic indicators of these two activities in each manufacturing industry type.
Journal Article
Factors affecting drug retention of Janus kinase inhibitors in patients with rheumatoid arthritis: the ANSWER cohort study
2022
This multi-center, retrospective study aimed to clarify the factors affecting drug retention of the Janus kinase inhibitors (JAKi) including baricitinib (BAR) and tofacitinib (TOF) in patients with RA. Patients were as follows; females, 80.6%; age, 60.5 years; DAS28-ESR, 4.3; treated with either BAR (n = 166) or TOF (n = 185); bDMARDs- or JAKi-switched cases (76.6%). The reasons for drug discontinuation were classified into four major categories. The drug retention was evaluated at 24 months using the Kaplan–Meier method and multivariate Cox proportional hazards modelling adjusted by confounders. Discontinuation rates for the corresponding reasons were as follows; ineffectiveness (22.3%), toxic adverse events (13.3%), non-toxic reasons (7.2%) and remission (0.0%). Prior history of anti-interleukin-6 receptor antibody (aIL-6R) ineffectiveness significantly increased the risk of treatment discontinuation due to ineffectiveness (p = 0.020). Aging (≥ 75 years) (p = 0.028), usage of PSL ≥ 5 mg/day (p = 0.017) and female sex (p = 0.041) significantly increased the risk of treatment discontinuation due to toxic adverse events. Factors not associated with treatment discontinuation were: number of prior bDMARDs or JAKi, concomitant MTX usage, difference of JAKi, and prior use of TNF inhibitor, CTLA4-Ig or other JAKi.
Journal Article
Tailoring exchange couplings in magnetic topological-insulator/antiferromagnet heterostructures
by
Liu, Yuxiang
,
Murata, Koichi
,
Che, Xiaoyu
in
639/301/1005/1007
,
639/301/119/2792
,
639/301/119/544
2017
Magnetic topological insulators such as Cr-doped (Bi,Sb)
2
Te
3
provide a platform for the realization of versatile time-reversal symmetry-breaking physics. By constructing heterostructures exhibiting Néel order in an antiferromagnetic CrSb and ferromagnetic order in Cr-doped (Bi,Sb)
2
Te
3
, we realize emergent interfacial magnetic phenomena which can be tailored through artificial structural engineering. Through deliberate geometrical design of heterostructures and superlattices, we demonstrate the use of antiferromagnetic exchange coupling in manipulating the magnetic properties of magnetic topological insulators. Proximity effects are shown to induce an interfacial spin texture modulation and establish an effective long-range exchange coupling mediated by antiferromagnetism, which significantly enhances the magnetic ordering temperature in the superlattice. This work provides a new framework on integrating topological insulators with antiferromagnetic materials and unveils new avenues towards dissipationless topological antiferromagnetic spintronics.
Heterostructures formed by the magnetic topological insulator Cr-doped (Bi,Sb)
2
Te and the antiferromagnet CrSb are shown to exhibit emergent interfacial magnetic phenomena that can be tuned with the heterostructure geometry.
Journal Article
Coherent photoelectrical readout of single spins in silicon carbide at room temperature
by
Nishikawa, Tetsuri
,
Murata, Koichi
,
Tsuchida, Hidekazu
in
142/126
,
639/766/1130/2798
,
639/766/119/1000
2025
Establishing a robust and integratable quantum system capable of sensitive qubit readout at ambient conditions is a key challenge for developing prevalent quantum technologies, including quantum networks and quantum sensing. Paramagnetic colour centres in wide bandgap semiconductors provide optical single-spin detection, yet realising efficient electrical readout technology in scalable material will unchain developing integrated ambient quantum electronics. Here, we demonstrate photoelectrical detection of single spins in silicon carbide, a material amenable to large-scale processing and electronic integration. With efficient photocarrier collection, we achieve a 1.7–2 times better signal-to-noise ratio for single spins of silicon vacancies with electrical detection than with optical detection suffering from saturating fluorescence and internal reflection. Based on our photoionisation dynamics study, further improvement would be expected with enhanced ionisation. We also observe single-defect-like features in the photocurrent image where photoluminescence is absent in the spectrum range of silicon vacancies. The efficient electrical readout in the mature material platform holds promise for developing integrated quantum devices.
Efficient quantum-state readout is key to quantum technologies. Here, the authors show room-temperature photoelectrical readout of single spins in silicon carbide, with a demonstrated detection efficiency superior to the conventional optical method.
Journal Article
Serum vitamin D status inversely associates with a prevalence of severe sarcopenia among female patients with rheumatoid arthritis
2021
Sarcopenia is an age-related disease with an increased risk of mortality. It is emerging that low serum 25-hydroxyvitamin D [25(OH)D] affects the sarcopenic state in general, but in rheumatoid arthritis (RA), these associations are not understood although the prevalence of vitamin D insufficiency is high in RA. We conducted a cross-sectional study of older female outpatients from our cohort (KURAMA) database. We measured skeletal muscle mass, handgrip strength, and gait-speed to diagnose severe sarcopenia. The serum 25(OH)D concentration was measured using electrochemiluminescence immunoassay. A total of 156 female patients with RA (sarcopenia:44.9%, severe sarcopenia: 29.5%, and without sarcopenia: 25.6%) were enrolled. Classification of vitamin D status at a cutoff point of median 25(OH)D concentration revealed that low 25(OH)D status was associated with a high prevalence of severe sarcopenia and with low measured values of muscle mass, handgrip, and gait speed. Furthermore, multivariable logistic regression analysis identified that low 25(OH)D status was associated with a high prevalence of severe sarcopenia (OR 6.00; 95% CI 1.99–18.08).The same association was observed when the cut-off value was set at 20 ng/ml. In components of sarcopenia, both low physical performance and muscle mass were associated with low 25(OH)D status. In conclusion, vitamin D status was inversely associated with severe sarcopenia, low physical performance, and low skeletal muscle mass. Modification of vitamin D status including vitamin D supplementation should be investigated as a therapeutic strategy for sarcopenic patients with RA.
Journal Article