A Method for Estimating Physician Stress Using Wearable Sensor Devices

The idea of Society 5.0 initiative has been proposed to solve various social problems by connecting virtual cyberspace and real physical space through information technology. When applying the idea to improve the work-life balance of physicians in the medical field, we must consider the increased stress owing to their long continuous working hours. Estimating the stress of physicians in their daily lives by the questionnaires is insufficient, because of the difficulty of accurate their activity recalling. By using bio-metric information such as heart rate, physical activity, and sleeping information, it was expected that the daily stress state of physicians with high accuracy. In this paper, we propose a method for estimating physician stress by analyzing bio-metric information acquired by wearing a wearable sensor device. The proposed method estimates the state of stress during daily activities by acquiring data on heart rate variability (HRV) during wakefulness as well as sleep depth during rapid eye movement (REM) and non-REM sleep. Up to seven physicians wore the wearable sensor device for the maximum of eight weeks and the sleep depth and low-/high-frequency (LF/HF) components of HRV were obtained. Our observation showed that physicians' root mean square of successive differences (rMSSDs) were constantly high in their healthy state. Therefore, the decreasing of this index can be used as an indicator of fatigue and stress. In addition, by combining LF/HF components to the rMSSDs, we may estimate the stress state of physicians and find personal stressors

Vertical Profiles of Ra-226 and Ra-228 Activity Concentrations in the Western Subarctic Gyre of the Pacific Ocean

The vertical activity concentration distributions of the radium isotopes, Ra-226 and Ra-228, which are useful as radiotracers, were obtained for the first time in the western Subarctic Pacific Gyre (WSAG). It was possible to detect short-lived Ra-228 present from the surface to 400 m depth by analyzing large seawater samples. Low Ra-228 and high Ra-226 activity concentrations in the surface layer in the WSAG were strongly influenced by upwelled deeper water with nutrients. The activity concentration distribution of Ra-226 especially was in good agreement with the silicate concentration distribution, which was consistent with previous reported findings. These distributions were uniform from the surface to 100 m of the dichothermal layer due to vertical mixing in winter. Ra-228 activity concentration decreased with water depth below the pycnocline and reached the undetectable level at 600 m which was within the oxygen minimum layer. Estimations of vertical fluxes of Ra-228 and nitrate according to Ra-228 decay indicated that the vertical transport by eddy diffusion was a minor process for the Ra-228 and nitrate fluxes, and lateral transport mainly affected Ra-228 in the intermediate warm water, that is, the mesothermal layer below the main pycnocline. Vertical mixing or submarine underground water and lateral transport to the WSAG could yield this Ra-228 in the intermediate depth

Altered diffusivity of the subarachnoid cisterns in the rat brain following neurological disorders

Background: Although changes in diffusion characteristics of the brain parenchyma in neurological disorders are widely studied and used in clinical practice, the change in diffusivity in the cerebrospinal fluid (CSF) system is rarely reported. In this study, free water diffusion in the subarachnoid cisterns and ventricles of the rat brain was examined using diffusion magnetic resonance imaging (MRI), and the effects of neurological disorders on diffusivity in CSF system were investigated. Methods: Diffusion MRI and T2-weighted images were obtained in the intact rats, 24 h after ischemic stroke, and 50 days after mild traumatic brain injury (mTBI). We conducted the assessment of diffusivity in the rat brain in the subarachnoid cisterns around the midbrain, as well as the lateral ventricles. One-way ANOVA and Kruskal–Wallis test were used to evaluate the change in mean diffusivity (MD) and MD histogram, respectively, in CSF system following different neurological disease. Results: A significant decrease in the mean MD value of the subarachnoid cisterns was observed in the stroke rats compared with the intact and mTBI rats (p < 0.005). In addition, the skewness (p < 0.002), maximum MD (p < 0.002), and MD percentiles (p < 0.002) in the stroke rats differed significantly from those in the intact and mTBI rats. By contrast, no difference was observed in the mean MD value of the lateral ventricles among three groups of rats. We proposed that the assessment of the subarachnoid cisterns, rather than the lateral ventricles, in the rat brain would be useful in providing diffusion information in the CSF system. Conclusions: Alterations in MD parameters of the subarachnoid cisterns after stroke provide evidence that brain injury may alter the characteristics of free water diffusion not only in the brain parenchyma but also in the CSF system