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Search Results: 1 - 10 of 198 matches for " Hiroyasu Ujike "
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Comfort in observing stereoscopic images reduced by vibration stimuli  [PDF]
Hiroshi Watanabe, Hiroyasu Ujike
Health (Health) , 2012, DOI: 10.4236/health.2012.411157
Abstract: Numerous studies have been conducted to illuminate the effect of image factors to reduce unexpected influence of stereoscopic images on healthy visual experience. In this paper, we introduce changes in the psychological and physiological indexes of observers of a stereo- scopic image disturbed by vibration stimuli. Forty-four healthy university students participated in the experiment. A programmable vibration table generated two types of vibrations (5 Hz and 20 Hz) and provided intermittent vibration stimuli to a stereoscopic projector installed on a vibration table. Our results showed that the frequency of vibration stimuli has a strong impact in evaluating the local comfort of subjects. Our results also showed that the indexes of visual fatigue increased after observation independent of the frequency. The activity status of the autonomic nervous system as a physiological index significantly increased after observing 3D images with vibration stimuli although the vibrational frequency did not have a significant effect on the activity status.
Psychological and physiological effects of stereoscopic movies of real-world scenes containing improper three-dimensional settings  [PDF]
Hiroshi Watanabe, Hiroyasu Ujike
Health (Health) , 2013, DOI: 10.4236/health.2013.57148
Abstract:

By using psychological and physiological indicators, the effects on the body of three-dimensional (3D) movies containing improper settings were evaluated with 139 university students. The experiment consisted of two sessions: 1) a 3D movie containing improper 3D settings was compared with a 2D movie containing only the rightside images presented to both eyes, and 2) the original 3D movie was compared with the same 3D movie altered to contain improper 3D settings. The results of this experiment demonstrated clear deterioration of the subjective psychological indicators (degree of motion sickness after watching the movies and comfort level at 1-min intervals during the movie) with respect to the 3D movie containing improper settings. On the other hand, the physiological indicators (LF/HF ratio indicating the status of the autonomic nervous system) changed as a result of watching a 3D movie, but were unaffected by the presence or absence of improper 3D settings.

The Influence of Dynamic Signs on Cyclists’ Braking Rates: A Systematic Study Using Immersive Virtual Reality  [PDF]
Hiroshi Watanabe, Nana Ito, Hiroyasu Ujike, Reiko Sakata, Munetaka Nishihira, Tsutomu Matsubara
Psychology (PSYCH) , 2017, DOI: 10.4236/psych.2017.89084
Abstract: Dynamic signs are signs that incorporate movement and are projected from a vehicle toward pedestrians or on the wall or floor of a public facility. Projection-based signage systems that are easy to install and move are becoming increasingly practical as a result of recent improvements in projector technology, and there is a need to accumulate knowledge on such signs and their interactions with people from an ergonomic perspective. This paper studies dynamic signs projected from parked cars (these signs warn that the car is about to reverse or open a door) with the goal to clarify the influence of these dynamic signs on the braking behavior of cyclists riding near the cars. In an experiment, we placed several parked cars in an immersive virtual reality space and created a system that allowed participants to move through the virtual space by steering a real bicycle. As participants rode past the row of parked cars, they took evasive actions to avoid a collision by actually operating the brake and handlebar in response to signs projected from cars warning that the car was about to reverse or open a door. For the experimental conditions, we looked at participant age groups, the method used to display the signs, and the timing of displaying the sign. The results suggest that the various experimental conditions produce different effects, and our discussion focuses on brake selection rates as a measure of cyclists’ responses to events.
Effects of visually simulated roll motion on vection and postural stabilization
Shigehito Tanahashi, Hiroyasu Ujike, Ryo Kozawa, Kazuhiko Ukai
Journal of NeuroEngineering and Rehabilitation , 2007, DOI: 10.1186/1743-0003-4-39
Abstract: Eighteen observers completed four experimental conditions, the order of which was counterbalanced across observers. Conditions corresponded to the four possible combinations of rotation direction of the visually simulated roll motion stimulus and the two different visual stimulus patterns. The velocity of the roll motion was held constant in all conditions at 60 deg/s. Observers assumed the standard Romberg stance, and postural movements were measured using a force platform and a head position sensor affixed to a helmet they wore. Observers pressed a button when they perceived vection. Postural responses and psychophysical parameters related to vection were analyzed.During exposure to the moving stimulus, body sway and head position of all observers moved in the same direction as the stimulus. Moreover, they deviated more during vection perception than no-vection-perception, and during no-vection-perception than no-visual-stimulus-motion. The postural movements also fluctuated more during vection-perception than no-vection-perception, and during no-vection-perception than no-visual-stimulus-motion, both in the left/right and anterior/posterior directions. There was no clear habituation for vection and posture, and no effect of stimulus type.Our results suggested that visual stimulus motion itself affects postural control, and supported the idea that the same visual motion signal is used for vection and postural control. We speculated that the mechanisms underlying the processing of visual motion signals for postural control and vection perception operate using different thresholds, and that a frame of reference for body orientation perception changed along with vection perception induced further increment of postural sway.Virtual Reality (VR) technology has developed rapidly thanks to progress in information technology and computer graphics. The applications of VR technology have expanded to various fields including health and medical services, the amusement industr
Pharmacological Modulation by Shakuyakukanzoto (Shao-Yao-Gan-Cao-Tang) and the Ingredients in Rat Intestinal Smooth Muscle  [PDF]
Hiroyasu Satoh, Kiminori Tsuro
Chinese Medicine (CM) , 2011, DOI: 10.4236/cm.2011.22012
Abstract: Shakuyakukanzoto (Shao-Yao-Gan-Cao-Tang), a formulation of Japanese herbal (Kampo) medicines, is composed of Paeoniae Radix and Glycyrrhizae Radix. Effects of Shakuyakukanzoto and the ingredients on rat intestinal tract were examined. Shakuyakukanzoto (0.01 - 0.3 mg/ml) relaxed a carbachol (CCh, 0.3 μM) - induced contraction in a concentration-dependent manner. Both components (Paeoniae radix and Glycyrrhizae radix) also relaxed the CCh-induced contraction. At 0.1 to 1 mM, their constituents (paeoniflorin and glycyrrhetic acid) and the metabolic products (18-α- and 18-β-glycyrrhetinic acids) exerted almost the same actions. The relaxations induced by Shakuyakukanzoto were not modified by 1 μM nicardipine, 10 μM suramin (ATP receptor inhibitor) and several K+ channel inhibitors, but was attenuated by 20 μM IBMX (a phosphodiesterase inhibitor). Also, IBMX inhibited the relaxations induced by paeoniflorin and glycyrrhetic acid, but not by other ingredients. Nicardipine decreased the relaxation of just 18-α-glycyrrhetinic acid. Even in non-treatment with CCh, Shakuyakukanzoto relaxed the intestinal tract. CCh (0.3 μM) elicited spontaneous contractions in 23% specimens, depressed by application of Shakuyakukanzoto. These results indicate that Shakuyakukanzoto causes a remarkable relaxation by the anti-cholinergic and the PDE inhibitory actions, but by minor contribution of Ca2+ channel inhibition. Thus, Shakuyakukanzoto exerts an anti-spasmodic action due to the interaction with pharmacological effects of its ingredients.
Out-of hospital cardiac arrest in Okayama city (Japan): outcome report according to the "Utsutein Style".
Hayashi,Hoei,Ujike,Yoshihito
Acta Medica Okayama , 2005,
Abstract: The purpose of this study was to evaluate the outcomes for out-of-hospital cardiac arrest (OHCA) and cardiopulmonary resuscitation (CPR) in the city of Okayama, Japan, during a 1-year period after the reorganization of defibrillation by Emergency Life-Saving Technicians (ELSTs) with standing orders of CPR. The data were collected prospectively according to an Utstein style between June 1, 2003 and May 31, 2004; OHCA was confirmed in 363 patients. Cardiac arrest of presumed cardiac etiology (179) was witnessed by a bystander in 62 (34.6%) cases. Of this group, ventricular fibrillation (VF) was documented in 20 cases (32.3%), and 1 patient (5%) was discharged alive without severe neurological disability. This outcome is average in Japan, but it is quite low level compared with Western countries because there is less VF in Japan. The Utstein style revealed that we must try to detect VF before the rhythm changes and to provide defibrillation as soon as possible in order to improve outcomes. Further research will be required to accurately evaluate OHCA in Okayama city.
Comparative Electropharmacological Actions of Some Constituents from Ginkgo biloba Extract in Guinea-pig Ventricular Cardiomyocytes
Hiroyasu Satoh
Evidence-Based Complementary and Alternative Medicine , 2004, DOI: 10.1093/ecam/neh044
Abstract: Effects of the constituents from Ginkgo biloba extract (GBE) on the action potentials and the ionic currents in guinea pig ventricular cardiomyocytes were investigated using whole-cell and current-clamp techniques. The constituents, ginkgolides A, B, C and quercetin, had depressant effects at 0.1–3μM on the action potential configuration. Ginkgolide A (1–3?μM) prolonged the action potential (action potential duration: APD) at 75% and 90% repolarizations (APD75 and APD90). However, ginkgolides B and C at low concentrations prolonged APD, but at higher concentrations (>1?μM) shortened APD. Quercetin at 3?μM prolonged the APD, but not at the lower concentrations. These constituents also inhibited the Vmax. The resting potential was unaffected. In voltage-clamp experiments, ginkgolides A and B (0.1–3?μM) markedly and concentration-dependently increased the Ca2
Pharmacological characteristics of Kampo medicine as a mixture of constituents and ingredients
Hiroyasu Satoh
Journal of Integrative Medicine (JIM) , 2013,
Abstract: Herbal medicine in Japan is termed as Kampo medicine, which is derived from traditional Chinese medicine. Shakuyakukanzoto (Shao-Yao-Gan-Cao-Tang) as a kind of Kampo formulations is composed of just two components; Paeoniae Radix and Glycyrrhizae Radix, which produced marked relaxation of intestinal tract. Mokuboito (Mu-Fang-Ji-Tang) inhibited cardiac ionic channel currents, and as a mixture also produced great vasodilatation. Sinomenine (a main ingredient of Mokuboito) as a single compound also caused the vasodilatation, but decreased it along with ageing. Gypsum containing in Mokuboito and Chotosan (Diao-Teng-San) caused more marked effects, as compared with those without Gypsum. On the other hand, Rokumigan (Liu-Wei-Wan), Hachimijiogan (Ba-Wei-Di-Huang-Wan) and Goshajinkigan (Niu-Che-Shen-Qi-Wan) increase in order the number of contained ingredients. The formulations with more herbs (ingredients) produced much more effective actions on rat aorta, presumably due to compensation of the decline of pharmacological sensitivity with ageing. Thus, there are some important differences between single chemical drugs and mixture drugs with many ingredients. The effects of Kampo medicine (mixture) are never just a sum of each effect induced by a lot of ingredients. For elder persons, furthermore, Kampo medicine exerts more effective actions.
A gauge invariant derivation of the AC Josephson frequency and a reconsideration of the origin of the phase of the order-parameter
Hiroyasu Koizumi
Physics , 2009,
Abstract: We derive the AC Josephson frequency using the gauge invariant equations of motion with including the battery-contact effect. The frequency is given as a sum of a contribution from an Aharonov-Bohm phase that arises when charged-partices pass through an electric field in the insulator and that from a chemical potential difference arising form the battery contact; each of them contributes $|q|V/h$ to the frequency where $q$ is the charge, thus, the sum is $2|q|V/h$. The observed Josepshon frequency, $2|e|V/h$, hence, means that the charge on the tunneling particles is $e$. A variety of derivations so far miss one of the above two contributions; the original derivation misses the first contribution due to the lack of inclusion of the electric field in the insulator. The present result indicates that the phase of the order-parameter does not arise from the number fluctuations of Cooper pairs. We present an alternative origin for it; we argue that a Berry phase that arises from spin-vortices is the origin.
Gamma-ray Polarimetry
Hiroyasu Tajima
Physics , 2003, DOI: 10.1016/S0168-9002(03)01808-4
Abstract: An astrophysics application of a low noise Double-sided Silicon Strip Detector (DSSD) is described. A Semiconductor Multiple-Compton Telescope (SMCT) is being developed to explore the gamma-ray universe in the 0.1-20 MeV energy band. Excellent energy resolution and polarization sensitivity are key features of the SMCT. We have developed prototype modules for a low noise DSSD system, which reached an energy resolution of 1.3 keV (FWHM) for 122 keV at 0 degree C. Results of a gamma-ray imaging test are also presented.
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