For ensuring the stable train operation, it is important to estimate accurately the aerodynamic forces acting on a train vehicle. In this study, the aerodynamic forces acting on a vehicle model standing on a coast configuration model were measured by wind tunnel experiments. The coast configuration model consists of an embankment on a windward side and a cutting on a leeward side. The coast configuration model was so prepared that the cutting height, the gradient of slope of the cutting and the distance from the vehicle to the cutting can be varied. The aerodynamic forces acting on the vehicle model standing on the coast configuration model were compared with the aerodynamic forces acting on vehicle standing on the normal embankment. The aerodynamic force coefficients were smaller as the cutting was higher, steeper and nearer the vehicle. This showed the possibility that the cutting reduced aerodynamic forces acting on vehicle standing on the coast configuration than that acting on vehicle standing on normal embankment.

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長範囲固定を要する成人脊柱変形手術患者コホートを後ろ向きに調査し，骨盤固定群・骨盤非固定群に分けて術後のX線計測値，HRQOLおよび腰椎関連ADLの障害の程度を調査した．術後X線計測値に関して差を認めなかったが，骨盤固定患者は非固定患者に比べ有意に術後体幹可動性に関連するADLが低下した．長範囲固定手術を計画するときに考慮すべき重要な情報の一つであり，患者・家族との共有が重要である．

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はじめに：更衣動作のうち下衣の着脱は成人脊柱変形患者の術後に制限されるADLの一つである．しかし，その制限の要因に具体的な根拠は示されていない．本研究では成人脊柱変形患者の術後における下衣更衣動作の自立と脊椎骨盤パラメータとの関係性を調査した．

対象と方法：2011年12月から2019年12月の期間に下位胸椎から骨盤までの脊椎後方固定術を施行した成人脊柱変形術後患者の111症例を対象とした．退院時に下衣更衣動作が自立しているものを自立群，そうでないものを介助群として，術前の股関節可動域と術前後の各X線パラメータについて群間比較を行った．

結果：自立群は36例，介助群は75例であった．両群とも手術により立位アライメントは改善されていた．術前の股関節可動域に自立群と介助群で有意差を認めなかったが，術後PTは自立群18.7±7.4 °，介助群24.6±9.7°であり介助群で有意に大きい結果となった（p＜0.01）．

結語：成人脊柱変形術後患者の下衣更衣動作を自立群と介助群で比較したところ，術前の股関節可動域に差はなかったが，術後の骨盤後傾が介助群で有意に大きかった．

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【目的】眼球運動が静的立位時の姿勢制御に及ぼす影響を明らかにするため、静的立位時の衝動性眼球運動（以下SEM）および滑動性追従運動（以下、SPEM）負荷時の眼球運動と重心動揺を同時測定し、両者の関係について検討した。

【対象および方法】健常成人15名（男性5名、女性10名、21.7±0.4歳、身長 1.64±0.09 m、BMI 20.4±0.66）を対象に、静的立位時における開眼、閉眼、10～30°のSEMおよびSPEM負荷条件での眼球電図を測定し、重心動揺の総軌跡長、Romberg率との関係について検討した。

【結果】総軌跡長は、閉眼条件に比べ、開眼、SEM、SPEM条件で減少したが、SEMに比べSPEM条件で増加した。SPEM条件で重心動揺とSPEM振幅との間に関連を認めなかった。Romberg率とSEMおよびSPEM条件での総軌跡長との間に正の相関関係を認めた。性別、身体特性には関連を認めなかった。

【結論】静的立位時のSPEM負荷は、SEM負荷に比べ重心動揺を増大させ、姿勢を不安定にさせることが示唆された。SPEMの姿勢不安定化効果は、SPEMにより生じるretinal flowの影響が推察された。

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The critical wind speed of overturning obtained by the RTRI detailed equation, which is used in the static analysis of railway vehicle overturning under cross wind, tends to be lower than that intuitively estimated because it assumes the superposition of the worst conditions. In order to improve the accuracy of the evaluation, the previous research focused on the aerodynamic coefficients that have the greatest influence on the calculation results, but few studies on the lateral vibrational inertia force have been conducted. Therefore, in order to evaluate the critical wind speed of overturning reflecting the actual conditions, we examined an evaluation method based on the measured value of the lateral vibrational acceleration.

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　Starting from March 2, 2020, schools of every kind were temporarily closed to prevent COVID-19 infections. Despite dispersed school attendance being enforced during the closure, temporary school closures continued until the end of May. Elementary and junior high school students’ exercise habits changed because they could not step out of their homes unless necessary or during an emergency. Accordingly, the purpose of this study was to evaluate the changes in exercise time before and during temporary closures among 5,619 elementary (boys and girls) and junior high school (male and female) students in three stages by school grade and gender, namely, increased, unchanged, and decreased. Participants were classified into six groups, which were compared based on the frequencies of the following variables: i) affiliation with an athletic organization (Yes and No); and ii) frequency of exercise with parents during school closure (more than thrice a week, once or twice a week, and less than thrice a month). Decrease in exercise time tended to be significantly higher among boys and girls who were in athletic clubs and exercised less than twice per week, together with male and female students who were in athletic clubs and exercised less than thrice per month. However, increase in exercise time tended to be significantly higher among girls and female students who were not in athletic clubs and exercised more than thrice per week as well as boys who exercised more than thrice per week, regardless of their affiliations with an athletic organization. The impact of each factor, athletic organization affiliation, and parental involvement varied based on grade and gender; however, at least the majority of children and students whose exercise time decreased, parental involvement was less than twice per week.

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　強い横風に起因する車両の横転事故は今もなお全国各地で発生している．本稿は走行中の大型車が横風により転倒する際，車両へ作用する空気力に着目することで，風特性・車両特性相互の視点から総合的に車両横転のメカニズムを解明することを目的とした．地面による風速欠損の影響を考慮した空気力係数，及び現地の風特性に基づく閾値超過確率を踏まえたガストファクターを算出し，また角運動方程式による横転発生時の風況検討，風洞試験・現地車両走行試験に基づく過渡空気力の考察を行うことで，車両が横転に至る際の現地風況条件（平均風速・風向）をまとめた横転リスク判断図を作成した．風況予測の精度確認手法をも併せて示し，横転判断システムの現場適用性について考察した．

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第1報においては試験に用いた試料の性質, 圧縮試験結果の一般的性質について述べた。圧縮試験の各段階についての詳細な解析, 検討については次報に述べる。

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Poor posture (thoracic hyperkyphosis) in children is reportedly caused by changes in their living environment. A previous study (conducted 30 years ago) reported that the position of the center of pressure (COP) in a child with an upright posture was approximately 40% from the heel. The present study aimed to determine the position and characteristics of the COP while standing in children aged 6–12 years. This study enrolled 83 elementary school students. A Win-Pod (Medicapteurs) platform was used to measure the COP. The COP position was expressed as a percentage from the heel as a relative ratio with a foot length of 100%. Spinal Mouse® was used to measure thoracic kyphosis, lumbar lordosis, sacral anteversion, and trunk inclination angles in the standing position. The COP position was 30.3±8.9% from the heel. We found positive correlations between the COP position, height, and weight. Further, the COP position was significantly more anterior in 28 upper elementary grade children (35.1 ± 9.2%) than in 25 middle (29.5 ± 8.6%) and 30 lower grade children (26.5 ± 6.7%). Regarding sex differences, the COP position was significantly more anterior in 46 boys (32.3 ± 9.8%) than in 37 girls (27.9 ± 6.9%). There was a weak positive correlation between the COP position and trunk inclination angle (r=0.251, p<0.05). Thus, we found that the COP position in modern children aged 6–12 years while standing was 30.3 ± 8.9% from the heel, indicating a shift toward the heel (backward) compared to that reported in previous studies.

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The critical wind speed of overturning is one of indices for the safety evaluations of railway vehicles against crosswind. The critical wind speed of overturning is defined as the wind speed when wheel loads on the upwind side becomes zero, and is often evaluated by the “RTRI’s detailed equation”. In the RTRI’s detailed equation, the lateral vibration inertia force of car bodies is considered as one of the acting forces affecting overturning. The inertia force can be obtained from the product of the lateral vibration acceleration and the mass, and the lateral vibration acceleration is assumed from past running test results. However, there are differences in position, direction and situation between the lateral vibration acceleration measured in the running tests and the lateral vibration acceleration in the calculation model of the RTRI’s detailed equation. In this paper, model experiments in a wind tunnel were conducted to clarify the effects of the differences with respect to the lateral vibration acceleration. Next, vehicle dynamics simulation was implemented to calculate the lateral vibration acceleration that occurs at the center of gravity of a car body under strong crosswinds. The results showed that the critical wind speed of overturning can be calculated accurately by using the simulation results of the lateral vibration acceleration that occurs at the center of gravity of the car body under strong crosswinds. In addition, a new method is proposed to estimate the lateral vibration acceleration using the track displacement data. Finally, when the critical wind speed of overturning was calculated assuming typical commuter vehicles, the wind speed obtained from the proposed new method was up to 2m/s higher than the wind speed obtained from the assumed equation in the RTRI’s detailed equation.

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To clarify the relationship between the downstream flow field of a windbreak fence and aerodynamic forces acting on a train placed downstream of the windbreak fence, wind tunnel tests with models were conducted. A 1/40-scale windbreak fence model (height H = 50 mm, hole diameter D = 0, 2, 6, and 10 mm, thickness T = 0.8, 1.6, 4.0, and 8.0 mm) and a vehicle model with square cross-section were used. Flow velocity and turbulence intensity were measured by PIV measurement. The pressure distribution around the train model was measured with differential pressure sensors. Effects of varying the thickness and hole diameter of the windbreak fence and the distance between the fence and the train on the flow fields and train aerodynamic characteristics are examined. As a result of the tests, pressure coefficients show that the pressure field on the upstream side of the train varies more considerably than that on the downstream side with varying the distance between the windbreak fence and the train. Hence, the variation of drag force is mainly caused by the change of pressure field on the upstream side of the train. The drag coefficient is minimized when the distance between the windbreak fence and the train is a certain value, which has been also shown in previous studies. In this study, the reason why the drag coefficient is minimized is clarified. Both averaged velocity and drag force acting on the train become lower as the ratio of fence thickness to hole diameter T/D becomes larger. Although T/D of real fences is about 0.1, T/D can be about 1 for wind tunnel tests. Hence, it is recommended that the ratio T/D of the fence model should be less than 1 for wind tunnel tests.

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