Tomoki Shiozawa

Changes in bone turnover markers during 14-day 6° head-down bed rest

Osteoporosis caused by exposure to microgravity represents a serious clinical concern, but the mechanisms have yet to be fully elucidated. The present research aimed to elucidate the effects of microgravity environments on bone turnover, with a specific focus on changes in bone resorption markers such as type I collagen cross-linked N-telopeptides (NTx) and deoxypyridinoline (Dpyr), for which scant data are available regarding detailed time course. Methods using 6° head-down bed rest were utilized to simulate a microgravity environment. Eleven adult male volunteers underwent 6° head-down bed rest for 14 days; measurements were made of serum and urine Ca concentrations, in addition to osteocalcin (OC), bone alkaline phosphatase (ALP), NTx, and Dpyr as bone turnover markers. By the end of bed rest, concentrations of bone ALP had significantly increased, but OC displayed a tendency toward decrease. Concentrations of Dpyr significantly increased from day 6, remaining elevated until the end of bed rest. Concentrations of NTx significantly increased on day 13 and at the end of bed rest. Serum and urinary concentrations of Ca increased significantly at the end of bed rest. Bone ALP represents a relatively early marker of osteoblast differentiation at the matrix maturation phase and OC is a late marker in osteoblast differentiation at the calcification phase. The present results therefore suggest an absolute increase in bone resorption and normal or reduced bone formation, together causing prominent uncoupling and rapid bone loss after simulated microgravity. Moreover, the present results suggest that bone resorption is enhanced at an early stage of exposure to microgravity environments.

Consideration of Indices to Evaluate Age-Related Muscle Performance by Using Surface Electromyography

Recently, there has been an increasing focus on the rapid reduction of muscles that are required for the bending of the hip joint during walking (flexor muscles around the hip joint) with age. The flexor muscles around the hip joint include femoral rectus and abdominal muscles. These muscles have been implicated in falling in the elderly people. In this study, we examined the smoothed surface electromyography (sEMG) of femoral rectus muscles during biofeedback training (BFT) of the dominant leg. To this end, we developed parameters for the measurement of shapes in the smoothed sEMG, and evaluated the changes in these parameters in the muscles with age. Reduction of the muscular regulation capacity due to aging can be detected by performing sEMG during BFT by using a parameter in the muscles.

Effect of a Stereoscopic Movie on the Correlation between Head Acceleration and Body Sway

Visually induced motion sickness (VIMS) is caused by sensory conflict, the disagreement between vergence and visual accommodation while observing stereoscopic images. VIMS can be measured by psychological and physiological methods. We quantitatively measured the head acceleration and body sway before and during exposure to a conventional 3D movie. The subjects wore a head mount display and maintained the Romberg posture for the first 60 s and a wide stance (midlines of the heels 20 cm apart) for the next 60 s. Head acceleration was measured using an Active Tracer with 50 Hz sampling. The Simulator Sickness Questioner (SSQ) was completed immediately afterward. For the SSQ sub-scores and each index for stabilograms, we employed two-way ANOVA with leg postures and presence/absence of stereoscopic images as factors. Moreover, we assumed that the input signal was the head acceleration in the transfer system to control the body sway and estimate the transfer function.

Evaluating indices of age-related muscle performance by using surface electromyography

Recently, there has been an increasing focus on the rapid reduction of muscles that are required for the bending of the hip joint during walking (flexor muscles around the hip joint) with age. The flexor muscles around the hip joint include femoral rectus and abdominal muscles. These muscles have been implicated in falling in the elderly. In this study, we examined the smoothed surface electromyography (sEMG) of femoral rectus muscles during biofeedback training (BFT) of the dominant leg. To this end, we developed parameters for the measurement of shapes in the smoothed sEMG, and evaluated the changes in these parameters in the muscles with age. Statistical analysis indicated that it was necessary to include the time constant of the exponential decay curve fit to maximal points during prolonged muscular contraction, to evaluate the changes with age by using the smoothed sEMG during BFT. Reduction of the muscular regulation capacity due to aging can be detected by performing sEMG during BFT by using the time constant.

Nonlinear Analysis for Evaluation of Age-Related Muscle Performance Using Surface Electromyography

Several electromyographic methods are currently used, but needle electromyography (nEMG) and surface electromyography (sEMG) are most often applied. To physiologically evaluate electromyographic wave patterns for the detection of abnormalities, the wave patterns obtained with nEMG or sEMG have been macroscopically examined, and subjectively judged by physicians.  nEMG findings are used for the evaluation of whether a disorder is neurogenic or myogenic, and if it is both neurogenic and myogenic, they provide important information about whether it is acute, subacute, or chronic (KIMURA, 1989). However, the probe is a needle electrode, which is percutaneously inserted into muscular tissues.  sEMG findings are used for various evaluations, such as the classification of trembling for the diagnosis of involuntary motion, the diagnosis or differential diagnosis of dystonia and spasm, and the identification of involuntary constrictor muscles (KIZUKA et al., 2006).  sEMG is further used for the determination of the electric potential through a nerve conduction examination (evoked EMG). In evoked EMG, the electrostimulation of peripheral nerves is percutaneously performed (KIMURA, 1989). The examination methods described, except for method B), are invasive and cause severe pain in patients. Generally, “smoothing” and “integration” refer to two ways of quantifying EMG energy over time; smoothing refers to continuously averaging out the peaks and valleys of a changing electrical signal. On the other hand, integration refers to measuring the area under a curve over a period of time. These methods are used to examine the relative degree of muscular contraction, and are also employed to provide a parameter for the evaluation of muscular training conditions (Aukee, 2002). However, the results obtained are affected by the location of the measuring electrodes and the shape and size of the probes. That is, EMG findings are macroscopically and subjectively evaluated, as described above, and no algorithm for the quantification of the degree of muscular abnormalities or recovery

Forms in Economics and Business Administration

From November 15th to 17th, 2013, the 76th Symposium of the Science on Form was held at Aoyama Gakuin University in Shibuya-ku, Tokyo, Japan. The theme of the symposium was “Forms recognized in Economics and Business Administration” (The Society for Science on Form, Japan, 2013). Due to their abstract nature, Economics and Business Administration have not received much attention academically in the field of science of form. Therefore, on this occasion, we found it necessary to take up this theme again to contribute to the advancement of the “Science of Form”. At the symposium, oral presentations were given on subjects related to “Economics or Business Administration and form”, in which the topics were not limited only to a tangible form, but also included form as an abstract concept. On the first day of the symposium, Professor Akiko Kamesaka from Aoyama Gakuin University School of Business Administration gave a presentation as an invited lecturer (Kamesaka, 2013). On the second day, Professor Takeshi Yoshida from Aoyama Gakuin University School of Business Administration also gave a presentation as a guest lecturer (Yoshida, 2013), and Professor Hiroki Takada from Fukui University Graduate School of Engineering gave a presentation as a special lecturer (Takada, 2013). In addition, some society members also gave insightful reports during general presentation sessions (Suzuki et al., 2013; Takaki, 2013). To commemorate these achievements, the editorial board of this journal FORMA of the Society of Science on Form planned to publish an issue specific to this symposium.

A New Concept of Cerebral Autoregulation Using Mathematical Expressions

Stress was induced by graded head-up tilt (HUT) in 13 healthy subjects, and their beat-by-beat values of cerebral blood flow velocity (CBV) [cm s−1] and arterial blood pressure (ABP) [mmHg] were measured. Low frequency (LF: 0.07–0.2Hz) and high frequency (HF: 0.2–0.4Hz) transfer function gains (TFGs) [(cm s−1)/mmHg] were calculated to assess the dynamic cerebral autoregulation (DCA). By mathematically expressing the transition of DCA during the HUT, a new concept of cerebral autoregulation was discovered. This type of cerebral autoregulation rapidly leads DCA to a different stationary state after exposure to a sudden change in the gravitational load.

Development of Train Simulator for Evaluation of Human-Machine Interface

Development of Train Simulator for Evaluation of Human-Machine Interface Kouichi YANAGAWA, Hitoshi TSUNASHIMA and Takashi KOJIMA 1 はじめに 列車の運転は,自動車と比較して運転が単調になり やすい特徴を有しており,ヒューマンエラーの原因の 一つに運転士の覚醒度低下が挙げられる.ヒューマン エラー事故の防止方策として,鉄道会社では乗務員の 教育・訓練が行われている.また,バックアップとし て自動列車停止装置(Automatic Train Stop: ATS)な どを採用してきた.一部の鉄道では,自動列車運転装 置(Automatic Train Operation: ATO)を導入し,運転 を自動化させている事例もある.しかし,自動化を進 めることにより運転士は監視作業が中心となり,覚醒 度低下が懸念される.自動車分野では,ドライバの生 体情報や運転挙動から居眠りを検知し,警告を与える 居眠り運転警報装置が研究されている 1) 2).鉄道にお いては,ヒューマンファクタに関する基礎的研究が行 われているが3),積極的な運転支援にまで至っていな いのが現状である.そこで,列車運転におけるヒュー マンエラーを事前に防止するために,人間の特性を考 慮した運転支援システムの開発が必要であると考えら れる.このようなシステムを開発するためには,運転 士がどのような情報認知を行い,それにもとづいてど のような判断を行い,行動をとるのかを把握すること が重要となる.このような運転行動を解析するために は,運転士の生体計測などを様々な条件のもとで行え る運転シミュレータが必要となる.そこで,本研究で は,人間 -機械系評価用列車運転シミュレータを開発 し 4) 5) ,運転士の生態計測を行っている.本稿では, 本装置の概要と立体視への展開について述べる. 2 シミュレータの構成 ヒューマンファクタに関する研究の実験手法として 運転シミュレータを用いるためには,実験の目的に即 した環境が柔軟に構築可能であることが有効である. この観点から,システムは,通常の運転操作が違和感 なく行える程度とし,研究目的からの必要性に応じて 機能を強化する方針で,最小の構成とした.また,ソ フトウェアを独自に作成することで,車両特性の変更 や路線の作成,また,運転支援システムの組み込み等 を可能にした.構成が簡単でかつ臨場感を与えるため に,ソフトウェアによる模擬を多く取り入れた. 本装置のシステム構成を図2に示す.車両制御コン ピュータ,運転台,計器盤表示モニタ,スピーカの車 両再現部と,視界生成コンピュータ,プロジェクタ, スクリーンの視界再現部,指令コンピュータから構成 される.運転士が操作する運転台のハンドル位置が車 両制御コンピュータに入力され,車両特性にもとづい て車両運動計算や音響の生成,計器盤画像の生成等を 行う.計算した車両位置は視界生成コンピュータに送 られる.この情報に視差を付加し,コンピュータグラ フィクスの視界画像を生成し,プロジェクタから前方 の 70インチスクリーンに投影する.計器の変更や運 転支援の表示システムの評価等が行えるように,計 器盤を計器盤表示モニタ上に表示した.また,指令コ ンピュータからは,事故の発生や駅の移動,運転デー タの記録等の操作が行える. 軌道不整と車両運動モデルによって車両の振動を計 算し,スクリーンの視界画像を揺らすことにより,