Propagation mechanism of non-uniform distribution of stress and strain in tension test

Elastic-plastic finite element analysis is carried out on tension test to check the uniformity of stress and strain that highly influences the result of numerical analysis in forming processes. Usually stress is calculated by dividing the force by the cross sectional area of the specimen and strain is calculated by the change in a limited gauge length. Basic assumptions are that stress and strain distributions be uniform in the cross section and between two gauge points and the cross section lie between two gauge points. Result of numerical analysis shows that stress and strain distributions are not necessarily uniform especially for those material with poor work hardening ratio. Initiation and propagation of mechanism of this non-uniformity is analyzed to propose a method for a precise measurement of stress and strain

血小板活性化因子生合成酵素の活性調節機構の解析

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 矢冨 裕, 東京大学講師 栗原 由紀子, 東京大学教授 酒井 寿郎, 東京大学教授 水島 昇, 東京大学教授 藤井 知行University of Tokyo(東京大学

Identifying vertebral fractures in the Japanese population using the trabecular bone score : a cross-sectional study

Background: The trabecular bone score (TBS) is reported to be an independent predictor of fracture risk in patients with primary or secondary osteoporosis. However, there have been few reports on its use in the Japanese population. This study aimed to investigate the risk factors for vertebral fracture in the Japanese population and to evaluate the usefulness of TBS. Methods: This cross-sectional study involved 279 patients aged 60–90 years in whom bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA). TBS was calculated based on the DXA scans. The presence or absence of vertebral fractures was assessed from T11 to L5. The patients were divided into those with vertebral fractures (VF group, n = 104) and those without vertebral fractures (non-VF group, n = 175). Results: Of the 104 patients in the VF group, 75 had 1 vertebral fracture and 29 had 2 or more fractures. The mean TBS was 1.28 in the VF group and 1.35 in the non-VF group (p  1.23). Conclusion: TBS was a significant indicator of vertebral fractures in the Japanese population and might contribute to identifying patients with vertebral fractures, particularly those with osteopenia who need pharmacologic therapy

Observation of a flat and extended surface state in a topological semimetal

A topological flatband, also known as drumhead states, is an ideal platform to drive new exotic topological quantum phases. Using angle-resolved photoemission spectroscopy experiments, we reveal the emergence of a highly localized possible drumhead surface state in a topological semimetal BaAl4 and provide its full energy and momentum space topology. We find that the observed surface state is highly localized in momentum, inside a square-shaped bulk Dirac nodal loop, and in energy, leading to a flat band and a peak in the density of state. These results establish this class of materials as a possible experimental realization of drumhead surface states and provide an important reference for future studies of fundamental physics of topological quantum phase transition

Low Back Pain and Lumbar Degeneration

Background: Baseball is one of the most popular sports in Asia. It is known that baseball can easily lead to back pain. However, there has been no survey of low back pain (LBP) and lumbar disc degeneration in Japanese professional baseball players to date. Purpose: To investigate the cause of LBP and lumbar degeneration in professional Japanese baseball players. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We retrospectively reviewed the medical records of Japanese professional baseball players with LBP who visited our hospital. Data were collected from July 2018 to April 2021. We also investigated whether the results differed between players in their 20s and 30s or between pitchers and fielders. Data analysis was performed using the chi-square test. Results: We surveyed 32 professional baseball players. The most frequent causes of LBP among players in their 20s (n = 21) were lumbar disc herniation (LDH; 57%) and spondylolysis (24%). Of the players with spondylolysis, 50% had adult-onset spondylolysis. Players in their 30s (n = 11) most commonly had discogenic pain (55%) as well as LDH and facet joint arthritis (each 18%). The incidence of lumbar intervertebral disc degeneration was significantly higher in players in their 30s (91%) than those in their 20s (14%), as was the incidence of Schmorl nodes and Modic type 1 changes. There was no significant difference in the cause of LBP or the incidence of lumbar intervertebral disc degeneration between pitchers and fielders (P = .59). Conclusion: Among professional baseball players in their 20s, lumbar degeneration was less common, and they most frequently developed diseases less related to degeneration, such as LDH. However, among players in their 30s, lumbar degeneration was more advanced, and degenerative diseases such as discogenic pain occurred more frequently. Research on training methods could lead to the prevention of LBP. Our data may be applicable to other professional athletes and will contribute to diagnosis and treatment

Predictors of sedation period for critical illness patients focusing on early rehabilitation on the bed

There are various interventions of rehabilitation on the bed, but these are time-consuming and cannot be performed for all patients. The purpose of this study was to identify the patients who require early mobilization based on the level of sedation. We retrospectively evaluated the data of patients who underwent physical therapy, ICU admission of > 48 h, and were discharged alive. Sedation was defined as using sedative drugs and a Richmond Agitation–Sedation Scale score of < − 2. Multiple regression analysis was performed using sedation period as the objective variable, and receiver operating characteristic (ROC) curve and Spearman’s rank correlation coefficient were performed. Of 462 patients admitted to the ICU, the data of 138 patients were analyzed. The Sequential Organ Failure Assessment (SOFA) score and non-surgery and emergency surgery cases were extracted as significant factors. The ROC curve with a positive sedation period of more than 3 days revealed the SOFA cutoff score was 10. A significant positive correlation was found between sedation period and the initial day on early mobilization. High SOFA scores, non-surgery and emergency surgery cases may be indicators of early mobilization on the bed in the ICU