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Yamakoshi T.,Kanazawa University | Ogawa M.,Kanazawa University | Matsumura K.,Kanazawa University | Miyazaki S.,Kanazawa University | And 5 more authors.
IEEJ Transactions on Electronics, Information and Systems | Year: 2012

The long-term aim of our research is to develop near infra-red spectroscopy for non-invasive measurement of blood alcohol concentrations. The absorption spectrum of ethyl-alcohol could possibly provide the means for such an approach, but the absorption bands of other molecules, such as glucose and acetaldehyde, together with the very low in vivo ethyl-alcohol concentrations (EAC), represent significant analytical challenges. Here we present results of our in vitro investigation of ethyl-alcohol absorption spectra, and the use of multiple linear regression analysis to predict EAC in the presence of glucose and acetaldehyde. We used ethyl-alcohol and mixed solutions of ethyl-alcohol, glucose, and acetaldehyde. The latter were divided into three experimental systems as ethyl-alcohol/glucose, ethyl-alcohol/acetaldehyde, and ethyl-alcohol/glucose/acetaldehyde solutions. The range of EAC used was the same as that found in blood. The results showed good correlation between the actual EAC and the predicted EAC (control; R = 0.99, mean absolute error (MAE) = 0.12 mg/ml: glucose system; R = 0.97, MAE = 0.18 mg/ml: acetaldehyde system; R = 0.99, MAE = 0.23 mg/ml: glucose & acetaldehyde system; R = 0.98, MAE = 0.19 mg/ml). We conclude that the change of glucose and acetaldehyde concentration does not measurably affect the absorption bands of ethyl-alcohol. © 2012 The Institute of Electrical Engineers of Japan. Source


Yamakoshi T.,Kanazawa University | Matsumura K.,National Institute of Mental Health | Kobayashi H.,Kanazawa University | Gotoh Y.,Kanazawa University | Hirose H.,Kinjo College
Transactions of Japanese Society for Medical and Biological Engineering | Year: 2010

Prolonged monotonous driving may lower a driver's awareness level as well as increasing their stress level due to the compulsion to maintain safe driving which may result in an increased risk of a traffic accident. There is therefore an opportunity for technological assessment of driver physiological status to be applied in-car, hopefully reducing the incidence of potentially dangerous situations. As part of our long-term aim to develop such a system, we describe here the investigation of differential skin temperature measurement as a possible marker of a drivers stress level. In this study, after giving informed consent 25 healthy male (n = 18) & female (n = 7) subjects (26.8 ± 8.0 S.D. yrs) were investigated under environment-controlled conditions, whilst being subjected to simulated monotonous travel at constant speed on a test-course. We acquired physiological variables, including facialskin temperature which consists of truncaland peripheralskin temperatures (T s) using thermography, beat-by-beat blood pressure (BP), cardiac output (CO), tota lperipheral resistance (TPR), and normalized pulse volume (NPV) used as an indicator of localperi pheral vascular tone. We then investigated the driver's reactivity in terms of skin temperatures with this background of cardiovascular haemodynamics. We found that the simulated monotonous driving produced a gradualdrop in peripheralTs following the driving stress, which, through interpretation of the TPR and NPV recordings, could be explained by peripheral sympathetic activation. On the other hand, the truncal Ts was not influenced by the stress. These findings lead us to suggest that truncal-peripheral differential Ts could be used as a possible index indicative of the driver's stress. In fact, a significant correlation was confirmed between stress reference of BP and differential skin temperatures. Source


Takehiro Y.,Kanazawa University | Matsumura K.,National Institute of Mental Health | Yamakoshi Y.,Chiba University | Hirose H.,Kinjo College | Rolfe P.,Oxford BioHorizons Ltd.
European Journal of Sport Science | Year: 2010

The aims of this study were to assess methods for performing physiological measurements in motor sports, and to carry out a preliminary study in athletes participating in kart racing. The measurement of physiological variables in motor sports is practically challenging, largely due to the restricted space available for sensors and instrumentation and to movement artefacts from driver's operations and car vibration, hence the paucity of publications. We performed a preliminary study of amateur racing kart athletes to assess the performance of basic measurement apparatus and to collect preliminary data on the possible influences of gravity on cardiovascular activity. We measured the vector magnitude of acceleration (G), instantaneous heart rate using electrocardiography, blood pressure with a wrist sphygmomanometer, eardrum temperature (taken as a measure of core body temperature) with a radiation thermometer, and lap time. The instrumentation functioned satisfactorily during karting on a racing circuit. In all participants during driving, heart rate was maintained at approximately 150 beats min 1. Time-frequency analysis of all heart rate data was performed to evaluate cardiac control mechanisms and this suggested that the observed rise in heart rate could be due to sympathetic acceleration. Furthermore, while we do not have sufficient data to draw firm conclusions, it is suggested that the rise in heart rate could be related to the G stresses to which the drivers were subjected. Cross-correlation analysis of the G and heart rate signals was performed in one participant and this showed a statistically significant correlation. We also found a statistically significant decrease in blood pressure (P<0.01) and a rise in eardrum temperature (P<0.01) immediately after the driving period. We conclude that although current sensors and instrumentation can allow basic monitoring of physiological variables in motor sport athletes, further developments are needed to allow more detailed investigations to be performed. Cardiovascular activity in response to G stresses warrants particular detailed investigation. © 2010 European College of Sport Science. Source


Yamakoshi T.,Kanazawa University | Matsumura K.,National Institute of Mental Health | Yamakoshi Y.,Chiba University | Hirose H.,Kinjo College | And 2 more authors.
Transactions of Japanese Society for Medical and Biological Engineering | Year: 2010

Motor racing drivers may be exposed to thermal stress, which can influence their performance and put them at risk of heat stroke. The aim of the work described here was to monitor core body temperature and other physiological and environmental variables continuously in racing kart drivers and to investigate the relationship between core body temperature and lap-time/lap-time-variability, the latter being an indication of driver performance. As an indication of core temperature we used the eardrum temperature, Teardrum, measured with a modified, extremely-compact radiation thermometer. We also measured instantaneous heart rate, the vector magnitude of acceleration, G, sweat weight, ambient temperature and relative humidity in the racing suit and full-face helmet, Ta(suit)/RHsuit/Ta(met)/RHmet, road temperature, and lap-time. The measuring instruments functioned satisfactorily during karting performed on a racing circuit. In all participants (n= 15: 30.9 ±6.4 S.D. yrs) during driving, we found that Teardrum gradually increased from 36.8°C to 38.2°C It is suggested that the observed rise in Teardrum could be due to the G stresses to which the driver's were subjected, as heat production of the body was increased due to the increased muscle activity against G during driving. In addition, we found that the degradation of the local environment around the body (Ta(suit)/max= 41.0°C,RHsuit/max=96.6%,Ta(met)/max= 41.0 °C, RHmet/max=93.5%) could be also be one of the major factors. We also found a statistically significant correlation between Teardrum and lap-time/lap-time-variability. These results suggest that monitoring of Teardrum could be of considerable importance in protecting racing drivers from heat stroke and assessing their performance during motor racing. Source


Lee J.H.,Kanazawa University | Matsumura K.,Kanazawa University | Yamakoshi K.,Kanazawa University | Rolfe P.,Harbin Institute of Technology | And 6 more authors.
IFMBE Proceedings | Year: 2013

Motor racing athletes, especially Grand Touring (GT) car racing drivers in the closed-cockpit category, can face lifethreatening situations caused by heat stroke. In this paper, a novel continuous tympanic temperature monitoring system, that could help to reduce this risk, is presented. The system consists of an earpiece containing an infrared-radiation-type tympanic thermometer and a micro-speaker. We validated the reliability of the system for tympanic temperature monitoring in 10 healthy volunteers (21.8 ± 1.0 S.D. years) using a temperature-controlled water bath. In addition, we evaluated the usefulness of the system with 2 professional drivers under real racing conditions in the 2010 SUPER GT International Series. The results showed strong correlation between the infrared-radiation tympanic temperature obtained by the present system and both the direct tympanic temperature (r = 0.994, n = 1119, P < 0.001) and the sublingual temperature (r = 0.972, n = 1119, P < 0.001) as a reference temperature. The mean difference between these temperatures was +0.09°C, and -0.08°C, and 95 % confidence interval (equal to 1.96 S.D.) was 0.21°C, and 0.44°C, respectively. In the field test, involving real competitive racing under severe conditions on a racing circuit, the system functioned well. These results suggest that our novel system has an acceptable performance in a race setting as a reliable tympanic temperature monitor and could help to improve safety of motor sports. © 2013 Springer-Verlag. Source

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