A helicopter ambulance is equipped with various kinds of aircraft instruments and medical devices. Electromagnetic compatibility (EMC) for these instruments and devices must conform to CISPR11. However, this standard is specified for a device operating individually. Thus, conformation to this standard does not necessarily guarantee EMC inside the helicopter ambulance in which various aircraft instruments and medical devices are operated simultaneously. Nevertheless, there is virtually no study that evaluates the effects of the electromagnetic environment inside a flying helicopter on aircraft instruments and medical devices. In the present study, we measured the extremely-low-frequency and intermediate-frequency magnetic fields and high-frequency electric fields inside a flying helicopter ambulance. We focused on seven types of medical equipment, and measured the electromagnetic environment based on the method provided in IEC60601-1-2:2014 under various situations. We demonstrated that the high-frequency electric fields inside a helicopter were 33 dB below the IEC60601-1-2:2014 immunity tolerance value, and the extremely-low-frequency and intermediate-frequency magnetic fields were 55 dB below the EN45502-2-1 immunity tolerance value, even when all the devices were being operated.
According to a survey by WHO, approximately one third of elderly persons aged 65 or above experience one or more falls every year, and the falls cause serious injuries. One of the risk factors for falls is impairment of the balance control function that is necessary to recover from perturbations during gait. Several previous studies have analyzed the motion of recovering from perturbations in the anteroposterior direction during gait to prevent human fall. For example, one method was to introduce an obstacle suddenly while walking during a treadmill test, and to suddenly stop the belt of the treadmill during gait. However, as these methods do not introduce perturbation to lose balance sideways (in frontal plane) during gait, the reactive balance control motion of recovering from an inversion perturbation remains unclear. In the present study, we investigated the differences in the reactive balance control motions to recover from perturbations in the anteroposterior direction and those to recover from perturbations in the mediolateral direction, using an ankle foot orthosis that we developed. The orthosis can reproduce the input motions of the ankle joint in six degrees of freedom by controlling six pneumatic cylinders simultaneously. We investigated the pattern of recovery motion from inversion perturbation during gait while the subject walked with the orthosis on a treadmill. In this experiment, the orthosis randomly increased the power of the subject's right ankle joint in the inversion direction during the right loading response phase as attempt to introduce inversion perturbation. The results of this experiment demonstrated that there were significant differences between the width of a non-perturbed step and the width of the step after inversion perturbation. On the other hand, the patterns of step length and step time after inversion perturbation were similar to those after anteroposterior perturbation during gait. The results also showed that there were significant differences between muscle activities (gastrocnemius, tibialis anterior, biceps femoris and rectus femoris) after perturbation in the anteroposterior direction and those in the mediolateral perturbation during gait.
Force plates and treadmills are commonly used to measure the ground reaction force (GRF) and center of pressure (COP) of walking. However, the location and condition of measurement are confined when using force plates and treadmills. To address this issue, we have developed a wearable insole-type force sensor for estimating GRF. In this study, we conducted COP measurements using the insole-type force sensor. The insole-type force sensor is equipped with an array of thin-film force sensors. The arrangement of thin-film force sensors is determined according to the subject's plantar pressure distribution while in a static and upright position, captured on pressure-sensitive paper. To measure plantar pressure changes in the longitudinal direction, sensors are placed in two-by-two fashion on the heel, metacarpophalangeal joint, and big toe areas. In addition, five sensors are placed for measuring changes in the horizontal direction. The total number of sensors used is smaller than that used in similar insole-type sensor. COP were estimated in five male subjects (age: 22.6 ± 1.5 years). Each subject wore the insole-type force sensor on the left foot. The measurements were made with the subject was standing on one leg or walking on the force plate. The COP trajectory calculated from the thin-film force sensor output was corrected for the inherent trajectory of the force plate using multiple regression analysis. In all subjects, the measured and estimated COP trajectories were within 10mm of each other after correction. The insole-type sensor allows easy measurement of COP while walking naturally.
The purpose of this study was to investigate how the posture during bathtub bathing affects the body and mind. Although many studies discussed comfort and safety of bathing, little has been studied from the perspective of biomechanics and neuroscience. In our two experiments, we manipulated bathers' posture and measured changes in biomechanical loads (torque at joints) and cerebral blood flow in frontal brain regions. Additionally, we also collected subjective evaluation of physical relaxation for each posture. The results of experiments with male subjects in the 20 s to 30 s showed that extending legs, in comparison to flexing legs, induced a physically relaxed state, which was revealed by subjective evaluation. Furthermore, we found significant decrease of joint torque in the ankle and hip and a significant increases of joint torque in the knee when legs were extended than when flexed. Our measurements indicated inhibition of neural activity in the left ventrolateral prefrontal region during leg extension. These results motivate further exploration of the possibility that physical relaxation with a less confined bathing posture may induce “liberation from verbal thinking”.
The aim of this study was to elucidate the effects of myocardial fiber orientation on the deformation of the left ventricular (LV) wall. An LV wall model was constructed by modeling the myocardial fiber structure as an anisotropic hyperelastic material. The shapes of the endocardium and epicardium were assumed to be two spheroids. LV wall deformation by constriction of the myocardial fibers was simulated for three fiber orientations:the myocardial fiber was oriented parallel to the short-axis plane (Case 1) ; the angle between the myocardial fiber and the short-axis plane varied linearly from +π/3 in the endocardium to -π/3 in the epicardium (Case 2) ; and the myocardial fiber was uniformly oriented at an angle of -π/3 with respect to the short-axis plane (Case 3). The results showed that the LV wall deformation was governed by the interaction among the constriction of fibers, the wall deformation as a continuum body, and the geometric constrains of the LV anatomy. Comparing the results of three cases revealed that the helical structure of fibers contributes to cause a twisting motion and efficient contraction of the LV wall, which produces a heterogeneous distribution of the deformation rates in the LV wall.