Chronodiagnostic acquisition of recovery speed of heart rate under bathing stress

Potential and efficiency of statistical learning closely intertwined with individuals' executive functions: a mathematical modeling study

Statistical learning (SL) is essential in enabling humans to extract probabilistic regularities from the world. The ability to accomplish ultimate learning performance with training (i.e., the potential of learning) has been known to be dissociated with performance improvement per amount of learning time (i.e., the efficiency of learning). Here, we quantified the potential and efficiency of SL separately through mathematical modeling and scrutinized how they were affected by various executive functions. Our results showed that a high potential of SL was associated with poor inhibition and good visuo-spatial working memory, whereas high efficiency of SL was closely related to good inhibition and good set-shifting. We unveiled the distinct characteristics of SL in relation to potential and efficiency and their interaction with executive functions.

An equivalent circuit model for onset and offset exercise response

Background

The switching exercise (e.g., Interval Training) has been a commonly used exercise protocol nowadays for the enhancement of exerciser’s cardiovascular fitness. The current difficulty for simulating human onset and offset exercise responses regarding the switching exercise is to ensure the continuity of the outputs during onset-offset switching, as well as to accommodate the exercise intensities at both onset and offset of exercise.

Methods

Twenty-one untrained healthy subjects performed treadmill trials following both single switching exercise (e.g., single-cycle square wave protocol) and repetitive switching exercise (e.g., interval training protocol). During exercise, heart rate (HR) and oxygen uptake (VO ₂) were monitored and recorded by a portable gas analyzer (K4b ², Cosmed). An equivalent single-supply switching resistance-capacitor (RC) circuit model was proposed to accommodate the observed variations of the onset and offset dynamics. The single-cycle square wave protocol was utilized to investigate the respective dynamics at onset and offset of exercise with the aerobic zone of approximate 70% - 77% of HR _max, and verify the adaption feature for the accommodation of different exercise strengths. The design of the interval training protocol was to verify the transient properties during onset-offset switching. A verification method including Root-mean-square-error (RMSE) and correlation coefficient, was introduced for comparisons between the measured data and model outputs.

Results

The experimental results from single-cycle square wave exercises clearly confirm that the onset and offset characteristics for both HR and VO ₂ are distinctly different. Based on the experimental data for both single and repetitive square wave exercise protocols, the proposed model was then presented to simulate the onset and offset exercise responses, which were well correlated indicating good agreement with observations.

Conclusions

Compared with existing works, this model can accommodate the different exercise strengths at both onset and offset of exercise, while also depicting human onset and offset exercise responses, and guarantee the continuity of outputs during onset-offset switching. A unique adaption feature by allowing the time constant

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and steady state gain to re-shift back to their original states, more closely mimics the different exercise strengths during normal daily exercise activities.

Unobtrusive approaches to monitoring vital signs at home

Monitoring of vital signs such as those by electrocardiogram (ECG) or respiratory activities everyday is significant even for healthy people since it would help locate acute or undetermined disorders before they become fatal. Monitoring of vital signs is done with sensors installed in household furniture or appliances, which come into direct contact with the body unobtrusively in everyday life. The data acquired with this modality are sometimes contaminated by various artifacts. Statistical procedures, however, extract meaningful outcome as the amount of data generated is enormous. A long-term monitoring on the stress ECG with this modality for 2 years was investigated. The result revealed a biological cycle wherein the recovery speed from the stress slowed down. It suggests that the unobtrusive monitoring produces a long-term health data that enable predicting of possible disorders in the near future.

E-healthcare at an experimental welfare techno house in Japan

An automated monitoring system for home health care has been designed for an experimental house in Japan called the Welfare Techno House (WTH). Automated electrocardiogram (ECG) measurements can be taken while in bed, in the bathtub, and on the toilet, without the subject's awareness, and without using body surface electrodes. In order to evaluate this automated health monitoring system, overnight measurements were performed to monitor health status during the daily lives of both young and elderly subjects.

Risk factors of sudden death in the Japanese hot bath in the senior population

A series of experiments were carried out to clarify the cause of death and the risk factors related to sudden death in the Japanese senior population while bathing in a Japanese style "hot bath." The biodynamic changes while bathing were carefully monitored under actual bathing situations occurring in both the winter and summer seasons. We observed double product (DP), total peripheral blood vessel resistance (TPR), cardiac output (CO), and blood vessel compliance (COMP) by measuring blood pressure, heart rate, pulse wave, and electrocardiogram (ECG). The finding of a high level of DP in the elderly suggests that more myocardial oxygen consumption is needed than for young adults, particularly in subjects with arrhythmia. Although the values for TPR and CO changed somewhat during bathing, the changes were considered normal and to be expected. However, more significant and substantial changes were observed during the winter experiment than during the summer experiment, no doubt owing to lower temperature of the bathing room. The value of COMP did not vary significantly between winter and summer subjects. Twelve subjects in the elderly developed ECG changes while bathing such as supraventricular extrasystole or ventricular tachycardia. No clinical significance was found in the biochemical analyses of the blood obtained before and after bathing. In conclusion, some subjects in the elderly showed risky changes in the above parameters and ECG, factors which may partially explain some of the causes of the many reported cases of lapse of consciousness and unexpected sudden death in the elderly while bathing especially in the winter season. Cold climate, hot water immersion, and hydrostatic pressure may affect their physiological compensation along with existing of coronary stenosis or weakness of respiratory function as a normal consequence of advanced age.