Structural reliability estimation based on quasi ideal importance sampling simulation

Masaaki Yonezawa,Shoya Okuda,Hiroaki Kobayashi 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.1

A quasi ideal importance sampling simulation method combined in the conditional expectation is proposed for the structural reliability estimation. The quasi ideal importance sampling joint probability density function (p.d.f.) is so composed on the basis of the ideal importance sampling concept as to be proportional to the conditional failure probability multiplied by the p.d.f. of the sampling variables. The respective marginal p.d.f.s of the ideal importance sampling joint p.d.f. are determined numerically by the simulations and partly by the piecewise integrations. The quasi ideal importance sampling simulations combined in the conditional expectation are executed to estimate the failure probabilities of structures with multiple failure surfaces and it is shown that the proposed method gives accurate estimations efficiently.

Scoliosis Caused by Limb-Length Discrepancy in Children

Kobayashi Kazuyoshi,Ando Kei,Nakashima Hiroaki,Machino Masaaki,Morozumi Masayoshi,Kanbara Shunsuke,Ito Sadayuki,Inoue Taro,Yamaguchi Hidetoshi,Mishima Kenichi,Ishiguro Naoki,Imagama Shiro 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.6

Study Design: Single-center retrospective study in pediatric patients.Purpose: The purpose of the study was to investigate the effects of the presence and severity of leg-length discrepancy (LLD) on scoliosis in children.Overview of Literature: LLD is a common orthopedic problem that can result in standing imbalance, low back pain, and stress fractures. It may cause structural changes in the spine over time, but the exact effect of LLD on scoliosis is unknown.Methods: The subjects were 23 children with LLD ≥20 mm (range, 27–65 mm) treated at Nagoya University Hospital between 2007 and 2017. Whole spine posteroanterior standing radiographs and whole lower limb radiographs in a supine position were recorded. Data were collected for demographics, LLD, Cobb angle, pelvic obliquity, and Nash/Moe index. Scoliosis was defined as a Cobb angle ≥10°. Leg length was measured from the top of the femoral head to the middle of the tibial plafond, and LLD was defined as the difference between the left and right leg lengths.Results: The patients (nine males and 14 females) had a mean age of 14.0 years (range, 5–18 years). The average LLD was 44.3±17.2 mm, with LLDs of 20 to 39 mm, 40 to 59 mm, and ≥60 mm in 13, five, and five subjects, respectively. The average Cobb angle was 13.0°±7.0°, and 15 subjects (65%) had scoliosis. Convexity of the scoliosis was to the short leg side in all cases. The Cobb angle was significantly related to the severity of the LLD (<i>R</i>=0.736, <i>p</i><0.01), pelvic obliquity (<i>R</i>=0.966, <i>p</i><0.01), and Nash/Moe index (<i>p</i><0.05).Conclusions: LLD is a common pediatric condition that can cause scoliosis of the spine. Severe scoliosis may develop if the LLD is ≥30 mm. Long-term studies are needed to examine the effect of LLD resolution on the elimination of scoliosis.

Image-based visual tracking for moving targets with active stereo vision robot

Masaaki Shibata,Nobuaki Kobayashi 제어로봇시스템학회 2006 제어로봇시스템학회 국제학술대회 논문집 Vol.2006 No.10

Persistence of Denosumab Therapy among Patients with Osteoporosis

Kobayashi Kazuyoshi,Ando Kei,Machino Masaaki,Morozumi Masayoshi,Kanbara Shunsuke,Ito Sadayuki,Inoue Taro,Yamaguchi Hidetoshi,Ishiguro Naoki,Imagama Shiro 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.4

Study Design: Retrospective study in a single center.Purpose: To examine denosumab persistence in patients of different ages with severe osteoporosis in Japan.Overview of Literature: Denosumab is an antibody drug used for the treatment of osteoporosis. It is mainly used in patients with severe osteoporosis who might have high motivation for treatment, and the need for only semi-annual subcutaneous injection might improve the continuation rate. However, no English-language articles have reported on denosumab persistence in the Japanese population, including young people, despite the importance of this issue in a super-aging society. Methods: The subjects started treatment with subcutaneous denosumab in our department from July 2013 until December 2017. Persistence rates were calculated using Kaplan-Meier curves. Patients were defined as “persistent” or “non-persistent” according to the use of therapy after 60 months.Results: The study included 101 patients (84 females) with a median follow-up period of 23.6±14.2 months. The persistence rate declined to 85.3%, 78.3%, 74.1%, 71.3%, and 69.3% at 12, 24, 36, 48, and 60 months, respectively. Age at the initiation of denosumab therapy differed significantly between non-persistent (n=31) and persistent (n=70) patients (81.3 vs. 72.8 years, <i>p</i> <0.01). Persistence was significantly lower in patients aged ≥80 years than in those aged <60 and 60–79 years (both <i>p</i> <0.01). The reasons for non-persistence of denosumab therapy were transfer to another hospital (n=13), interruption of outpatient visits (n=11), dental treatment (n=4), adverse events (n=2), and patient request (n=1).Conclusions: Persistence was significantly lower in patients aged ≥80 years than in patients of other ages, and strategies promoting persistence are needed for these elderly patients.

Structural reliability estimation based on quasi ideal importance sampling simulation

Yonezawa, Masaaki,Okuda, Shoya,Kobayashi, Hiroaki Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.1

A quasi ideal importance sampling simulation method combined in the conditional expectation is proposed for the structural reliability estimation. The quasi ideal importance sampling joint probability density function (p.d.f.) is so composed on the basis of the ideal importance sampling concept as to be proportional to the conditional failure probability multiplied by the p.d.f. of the sampling variables. The respective marginal p.d.f.s of the ideal importance sampling joint p.d.f. are determined numerically by the simulations and partly by the piecewise integrations. The quasi ideal importance sampling simulations combined in the conditional expectation are executed to estimate the failure probabilities of structures with multiple failure surfaces and it is shown that the proposed method gives accurate estimations efficiently.

Efficacy of Anal Needle Electrodes for Intraoperative Spinal Cord Monitoring with Transcranial Muscle Action Potentials

Kazuyoshi Kobayashi,Kei Ando,Hideki Yagi,Kenyu Ito,Mikito Tsushima,Masayoshi Morozumi,Satoshi Tanaka,Masaaki Machino,Kyotaro Ota,Yukihiro Matsuyama,Naoki Ishiguro,Shiro Imagama 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.4

Study Design: Retrospective study. Purpose: To examine the relationship between postoperative bowel bladder disorder (BBD) and the efficacy of needle electrodes for the external anal sphincter (EAS) in intraoperative spinal cord monitoring with transcranial muscle action potentials (Tc-MsEP). Overview of Literature: Spinal surgery for spina bifida, spinal cord tumor, and spinal tethered cord syndrome has a high rate of postoperative BBD. Monitoring of the EAS with Tc-MsEP is frequently performed during spinal surgery. We initially used plug-surface electrodes for this purpose, but have more recently switched to needle electrodes for the monitoring of the EAS. To date, there has been no comparison between the utility of these electrodes. Methods: Waveform derivation, exacerbation of postoperative BBD, and sensitivity and specificity for prediction of BBD by 70% amplitude reduction of EAS activity using needle and plug-surface electrodes were investigated in 239 spine surgeries. The cut-off for the % drop in amplitude for BBD prediction was determined for EAS monitoring using a needle electrode. Results: The overall rate of postoperative BBD aggravation was 7.1% (17/239 cases), with the individual rates using needle and plug-surface electrodes being 6.9% (8/116) and 7.3% (9/123), respectively. The waveform derivation rate was significantly higher using needle electrodes (91.3% [106/116] vs. 76.4% [94/123], p <0.01). In patients with baseline waveform detection, the sensitivity and specificity for postoperative BBD were similar in the two groups. With needle electrodes, a cutoff amplitude of Tc-MsEP for the EAS at the end of surgery of 25% of the baseline amplitude had a sensitivity of 89% and specificity of 82% for the prediction of postoperative BBD aggravation. Conclusions: The significantly higher waveform derivation rate using needle electrodes suggests that these electrodes are effective for monitoring the EAS in spinal surgery in cases with preoperative BBD.

Perioperative Management of Patients with Hemophilia during Spinal Surgery

Kazuyoshi Kobayashi,Shiro Imagama,Kei Ando,Kenyu Ito,Mikito Tsushima,Masayoshi Morozumi,Satoshi Tanaka,Masaaki Machino,Kyotaro Ota,Yoshihiro Nishida,Naoki Ishiguro 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.3

Study Design: Single-center retrospective study. Purpose: To optimize the perioperative management of patients with hemophilia who are undergoing spinal surgery. Overview of Literature: Hemophilia is a rare disease in which there is a tendency of bleeding because of a congenital deficiency in blood coagulation factor activity. There has been no previous report on spinal surgery in patients with hemophilia. Methods: The subjects were five patients (all males) with hemophilia who underwent spinal surgery at Nagoya University Hospital. Two patients had hemophilia A (deficiency of factor VIII) and three had hemophilia B (deficiency of factor IX). The mean age at the time of surgery was 63 years (range, 46–73 years). The following surgeries were performed: posterior lumbar interbody fusion (PLIF) in two patients, and lumbar fenestration, cervical laminoplasty and lumbar fenestration, and cervical laminoplasty and PLIF in one patient each. Results: Coagulation factor at a mean dose of 4.8 ×103 U (range, 3–6 ×103 U) was intravenously injected before surgery, and a mean dose of 5.2 ×103 U (rang, 4–6 ×103 U) was continuously administered for 24 hours after surgery. Factor activity was maintained at ≥80% until postoperative day 14 and at ≥50% thereafter. The average duration of surgery was 178 minutes (range, 133–233 minutes), the estimated blood loss was 661 mL (range, 272–1,344 mL), and a drain tube was left subfascially in place for 2 days in all patients. Reoperation due to postoperative surgical site infection was required in one patient, but there were no complications due to hemorrhagic diathesis. The total dose of coagulation factor administered during hospitalization was 102 ×103 U (range, 46–198 ×103 U). Conclusions: Coordination with a hematologist and dose adjustment of the coagulation factor preparation to maintain a target level of coagulation factor activity facilitated a smooth postoperative course with perioperative control of bleeding during spinal surgery for patients with hemophilia.

23-hydroxyursolic acid causes cell growth-inhibition by inducing caspase-dependent apoptosis in human cervical squamous carcinoma HeLa cells.

Takaya, Makiko,Nomura, Masaaki,Takahashi, Tatsuo,Kondo, Yoko,Lee, Kyung-Tae,Kobayashi, Shinjiro Potamitis Press 2009 Anticancer research Vol.29 No.4

<P>BACKGROUND: There are few reports on the biological activities of 23-hydroxyursolic acid (23-HUA). The mechanism of growth-inhibition induced by 23-HUA, isolated from Cussonia bancoensis, in human cervical squamous carcinoma HeLa cells is hereby investigated. MATERIALS AND METHODS: The growth-inhibitory activity was measured by MTS assay. Caspases activation and expression of apoptosis-related proteins were detected by Western blotting. Apoptotic cells were observed by morphological analysis with Hoechst 33342. RESULTS: 23-HUA inhibited the growth of HeLa cells in a concentration dependent manner. Proteolytically generated fragments of caspase-3, -8 and -9 were observed in HeLa cells treated with 60 microM 23-HUA. The expression of Bcl-X(L), an anti-apoptotic protein, was markedly decreased by 60 microM 23-HUA. Morphological analysis showed that apoptotic changes occurred after treatment with 60 microM 23-HUA, and the changes were inhibited by a pan-caspase inhibitor, Z-VAD-FMK. CONCLUSION: These results indicate that 23-HUA causes potent growth-inhibition by the induction of apoptosis via activation of caspases in HeLa cells.</P>

A Study on Cluster Lifetime in Multi-HopWireless Sensor Networks with Cooperative MISO Scheme

Huang, Zheng,Okada, Hiraku,Kobayashi, Kentaro,Katayama, Masaaki The Korea Institute of Information and Commucation 2012 Journal of communications and networks Vol.14 No.4

As for cluster-based wireless sensor networks (WSNs), cluster lifetime is one of the most important subjects in recent researches. Besides reducing the energy consumptions of the clusters, it is necessary to make the clusters achieve equal lifetimes so that the whole network can survive longer. In this paper, we focus on the cluster lifetimes in multi-hop WSNs with cooperative multi-input single-output scheme. With a simplified model of multi-hop WSNs, we change the transmission schemes, the sizes and transmission distances of clusters to investigate their effects on the cluster lifetimes. Furthermore, linear and uniform data aggregations are considered in our model. As a result, we analyze the cluster lifetimes in different situations and discuss the requirements on the sizes and transmission distances of clusters for equal lifetimes.

Multi-Carrier Multi-Rate Modem for Universal FDMA/TDMA system

Yamashita, Fumihiro,Tabata, Masaaki,Kobayashi, Kiyoshi,Kazama, Hiroshi 통신위성우주산업연구회 2006 Joint Conference on Satellite Communications Vol.2006 No.-

We introduce a new multi-carrier multi-rate modem (MCMRM) module designed to support Universal FDMA/TDMA systems. Universal FDMA/TDMA is a new system that flexibly supports MF-TDMA and TDMA as well as multi-rate FDMA. We believe that the Universal FDMA/TDMA system will allow both system operators and customers to utilize frequency and/or time resources more efficiently than is possible with conventional systems. To implement this system, we have developed a new MCMRM module. This module has advanced functions such as a novel frequency multiplexer/demultiplexer, multi-carrier frequency decomposition/regeneration, and multi-carrier burst demodulation. This paper provides a detailed outline of the recently developed functions and an experimental evaluation of their performance. Measured results from the experiments demonstrate the feasibility of developed MCMRM module.