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Normal Values of Diffusion Tensor Magnetic Resonance Imaging Parameters in the Cervical Spinal Cord
Kazuki Chagawa,Shunka Nishijima,Tsukasa Kanchiku,Yasuaki Imajo,Hidenori Suzuki,Yuichiro Yoshida,Toshihiko Taguchi 대한척추외과학회 2015 Asian Spine Journal Vol.9 No.4
Study Design: Prospective study. Purpose: We evaluated the usefulness of diffusion tensor imaging (DTI) in diagnosing patients with cervical myelopathy by determining the accuracy of normal DTI parameter values. Overview of Literature: DTI can visualize white matter tracts in vivo and quantify anisotropy. DTI is known to be more sensitive than conventional magnetic resonance imaging (MRI) in detecting subtle pathological changes of the spinal cord. Methods: A total of 31 normal subjects (13 men and 18 women; age, 23–87 years; mean age, 46.0 years) were included in this study. The patients had no symptoms of myelopathy or radiculopathy. A Philips Achieva 3-Tesla MRI with SE-type Single Shot EPI was used to obtain diffusion tensor images. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured as DTI parameters on axial sections of several cervical levels. Subjects were divided into two groups: >40 years (n=16) and ≤40 years (n=15). A paired t-test was used to compare significant differences between the groups. ADC and FA values were most stable on axial sections. Results: For all subjects, mean ADC and FA values were 1.06±0.09×10−3 mm2/sec and 0.68±0.05, respectively. ADC was significantly higher in subjects >40 years of age than in those ≤40 years. There was no significant difference in FA values between the two groups. The mean ADC value was significantly higher in normal subjects >40 years of age than in those ≤40 years. Conclusions: It is important to consider age when evaluating cervical myelopathy by DTI.
Kazuki Fujimoto,Kazuhide Inage,Yawara Eguchi,Sumihisa Orita,Miyako Suzuki,Go Kubota,Takeshi Sainoh,Jun Sato,Yasuhiro Shiga,Koki Abe,Hirohito Kanamoto,Masahiro Inoue,Hideyuki Kinoshita,Masaki Norimoto 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.5
Study Design: Cross-sectional observational study. Purpose: To compare measurements of appendicular skeletal muscle mass (ASMM) and whole fat mass (WFM) obtained using dualenergy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) among patients with low back pain (LBP). Moreover, the study investigated the correlation between BIA-based ASMM and DXA-based bone mineral density (BMD). Overview of the Literature: If reliable, BIA may be a useful alternative to DXA as a screening tool for sarcopenia and osteoporosis among patients with LBP. Methods: Measurements were performed in 130 patients, including BMD of the lumbar spine and femoral neck. The correlation between DXA and BIA as well as between BIA-ASMM and BMD were evaluated. Results: BIA and DXA were highly correlated in both male and female patients (r =0.73–0.90, p <0.0001). However, BIA consistently overestimated ASMM by 1.5–2.5 kg on an average (p <0.0001) and underestimated WFM (−4.0 to −2.7 kg) on an average (p <0.0001). BIA-based ASMM correlated with BMD of the lumbar spine in both male and female patients (r =0.28–0.37, p ≤0.02) and that of the femoral neck (r =0.34–0.51, p ≤0.005). Regarding the calculated skeletal muscle index (SMI: ASMM/height [m2]) used as a criterion for sarcopenia, BIA-based SMI correlated with BMD of the lumbar spine in male patients (r =0.44, p =0.0004) and that of the femoral neck in female patients (r =0.33, p =0.009). Conclusions: BIA may be a favorable alternative to DXA as a screening tool for sarcopenia and osteoporosis among patients with LBP. Considering the overestimation of BIA-based ASMM and SMI, we recommend using the cutoff values for sarcopenia of 7.9 kg/m2 for males and 6.1 kg/m2 for females.
Minimum duration for presenting tactile stimuli to perceive stimulus locations on the palm
Kazuki Sakai,Kentaro Kotani,Satoshi Suzuki,Takafumi Asao 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5
The duration for presenting tactile stimuli to generate certain images are important for developing tactile displays with effective information processing since such duration affects human short term memory, which determine accurate and effective perception for tactile information. In this study the experiment was conducted to obtain the duration required for generating spatial images from tactile stimuli. A total of five subjects participated in the experiment, where they performed two-point discrimination task with tactile stimuli ranging from 100ms to 300ms of stimulus duration. As a result, less than 200ms of duration lowered the performance of two-point differential threshold when two consecutive stimuli were given without inter-stimulus intervals. These results implied that less than 200ms of duration was not enough for identifying spatial information associated with tactile stimuli. The quantitative data obtained in this study give some insight for developing a mental model for identifying tactile spatial information.
Minimum Duration for Presenting Tactile Stimuli to Perceive Stimulus Locations on the Palm
( Kazuki Sakai ),( Kentaro Kotani ),( Satoshi Suzuki ),( Takafumi Asao ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-
The duration for presenting tactile stimuli to generate certain images are important for developing tactile displays with effective information processing since such duration affects human short term memory, which determine accurate and effective perception for tactile information. In this study the experiment was conducted to obtain the duration required for generating spatial images from tactile stimuli. A total of five subjects participated in the experiment, where they performed two-point discrimination task with tactile stimuli ranging from 100ms to 300ms of stimulus duration. As a result, less than 200ms of duration lowered the performance of two-point differential threshold when two consecutive stimuli were given without inter-stimulus intervals. These results implied that less than 200ms of duration was not enough for identifying spatial information associated with tactile stimuli. The quantitative data obtained in this study give some insight for developing a mental model for identifying tactile spatial information.
Readiness Estimation for a Take-Over Request in Automated Driving on an Expressway
Ryohei Suzuki,Hirokazu Madokoro,Stephanie Nix,Kazuki Saruta,Takashi K. Saito,Kazuhito Sato 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11
Automated driving is attracting attention as a solution to road traffic problems. At Level 3, a take-over request (TOR) is issued to transfer driving operations from the system to a driver when it is unable to continue. In such cases, the driver must be monitored to ensure a proper takeover of the driving operations. This study aims to measure drivers’ brain activity before and after the TOR by analyzing time-series signals of brain activity with machine learning algorithms. We developed driving scenarios with a TOR trigger on a rainy expressway at night. We used a portable functional near-infrared spectroscopy (fNIRS) device to measure cerebral blood oxygenation changes (ΔHbO) at the frontal pole. We used a long short-term memory (LSTM) network on this data for time-series learning and prediction after multivariate and multilayering modifications to improve accuracy. We conducted driving questionnaires beforehand and used two classification methods to categorize subjects into several groups with similar driving characteristics. Experimental results of a ΔHbO drop revealed that brain activity tended to decrease during automated driving. Moreover, success in obstacle avoidance and mean squared error (MSE) for each driver group demonstrated that the behavior toward an obstacle after the TOR trigger influenced changes in brain activity.
Keizo Kato,Kazuki Takahashi,Keisuke Suzuki,Takayuki Sato,Kazunari Shinbo,Futao Kaneko,Hidehiko Shimizu,Nozomu Tsuboi,Toyoyasu Tadokoro,Shinichi Ohta 한국물리학회 2005 Current Applied Physics Vol.5 No.4
Organic light emitting diodes (OLEDs) with nanostructured ultrathin layers inserted at the interface between electron- and hole-transport layers were investigated. The fundamental structure of the OLEDs fabricated by a vacuum evaporation method wasindium-tin-oxide (ITO) anode/copper phthalocyanine (CuPc)/N,N0-diphenyl-N,N0-bis(3-methylphenyl)-1,10-diphenyl-4,40-diamine(TPD)/8-hydroxyquinoline aluminum (Alq3)/LiF/Al cathode. Fullerene (C60) and rhodamine B (RhB) molecules were used as thenanosutructured ultrathin layers inserted at the interface between the Alq3 and TPD layers. The electroluminescent (EL) propertieshave been measured for the OLEDs with C60 and RhB ultrathin layers and the dependences on the thickness and the position of theinserted layers were examined. For the OLEDs with the C60 ultrathin layer, the improvements of the drive voltage and EL eciencywere observed. The OLED with the inserted C60 ultrathin lm of a monolayer thickness showed the highest eciency, which wastwice as large as that without C60 layer. On the contrary, the improvements were not observed for the OLEDs with the RhB ul-trathin layer..
Yawara Eguchi,Munetaka Suzuki,Hajime Yamanaka,Hiroshi Tamai,Tatsuya Kobayashi,Sumihisa Orita,Kazuyo Yamauchi,Miyako Suzuki,Kazuhide Inage,Kazuki Fujimoto,Hirohito Kanamoto,Koki Abe,Masaki Norimoto,Tom 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.3
Study Design: Retrospective observational study. Purpose: We considered the relationship between spinal alignment and skeletal muscle mass on clinical outcomes following a surgery for lumbar spinal stenosis (LSS). Overview of Literature: There are no reports of preoperative factors predicting residual low back pain following surgery for LSS. Methods: Our target population included 34 women (mean age, 74.4 years) who underwent surgery for LSS. Prior to and 6 months after the surgery, systemic bone mineral density and lean soft tissue mass were measured using dual-energy X-ray absorptiometry. Skeletal muscle mass index (SMI) was calculated as the sum of the arm and leg lean mass in kilograms divided by height in meters squared. The spinal alignment was also measured. Clinical outcomes were evaluated using the Japanese Orthopedic Association scoring system, leg and low back pain Visual Analog Scale, and Roland–Morris Disability Questionnaire (RDQ). Additionally, we examined the bone mineral density, skeletal muscle mass, and spinal alignment before and after the surgery. We used the Spearman correlation coefficient to examine the associations among clinical outcomes, preoperative muscle mass, and spinal alignment. Results: Sarcopenia (SMI <5.46) was observed in nine subjects (26.5%). Compared with normal subjects (SMI >6.12), RDQ was significantly higher in subjects with sarcopenia (p =0.04). RDQ was significantly negatively correlated with SMI (r =−0.42, p <0.05). There was a significant positive correlation between postoperative RDQ and pelvic tilt (PT; r =0.41, p <0.05). SMI and PT were significantly negatively correlated (r =−0.39, r <0.05). Conclusions: Good postoperative outcomes were negatively correlated with low preoperative appendicular muscle mass, suggesting that postoperative outcomes were inferior in cases of decreased appendicular muscle mass (sarcopenia). Posterior PT due to decreased limb muscle mass may contribute to postoperative back pain, showing that preoperatively reduced limb muscle mass and posterior PT are predictive factors in the persistence of postoperative low back pain.
Kawasaki, Koji(카와사키 코지),Suzuki, Kazuki(스즈키 카즈키),Lee, Kwang-Ho(이광호),Kim, Do-Sam(김도삼) 한국해안해양공학회 2013 한국해안해양공학회 논문집 Vol.25 No.6
2011년 일본동북지방 대지진 이후, 규모 9.0의 토카이, 토난카이 및 난카이 대규모 지진이 일본 서부의 태평양 해안을 내습할 수 있다는 주장이 제기되고 있다. 본 연구에서는 태평양 해안과 일본의 주요 3대 만인 도쿄만과 이세만 그리고 오사카만에서 규모 9.0의 토카이, 토난카이 및 난카이 대규모 지진에 의해 발생하는 지진해일의 전파 특성을 수치적으로 검토하였다. 본 연구에서 수행된 수치해석결과 M9.0의 지진에 의해 발생하는 태평양 해안에서의 지진해일 높이는 M8.7의 지진에 비해 그 크기가 약 2배에 달하며 지진원으로부터 떨어진 일부 지역에서는 빠른 지진해일의 도달시간을 확인하였다. 또한, 페쇄된 만의 영향에 의해 오랜 시간 동안 만내에서 고수위가 지속됨을 알 수 있었다. After the 2011 Tohoku Earthquake, it has been pointed out that Tokai, Tonankai and Nankai massive earthquakes with a magnitude of 9.0 could strike the Pacific coasts in western Japan. This study aims at investigating numerically propagation characteristics of tsunami generated by a 9.0 magnitude Tokai, Tonankai and Nankai massive earthquakes on the Pacific coasts and three major bays in Japan, Tokyo Bay, Ise Bay and Osaka Bay. It was revealed from the numerical results that the tsunami heights on the Pacific coasts for M9.0 earthquake were about twice as much as those for M8.7 earthquake and the first tsunami arrival time was faster at some areas distant from the tsunami source. Moreover, high water level in the bays was recognized to continue for a long time because of the enclosed bays.