The suppression of the first wave of COVID-19 in Japan is assumedly attributed to people’s increased risk perception after acquiring information from the government and media reports. In this study, going out in public amidst the spread of COVID-19 infections was investigated by examining new polymerase chain reaction (PCR) positive cases of COVID-19 and its relationship to four indicators of people going out in public (the people flow, the index of web searches for going outside, the number of times people browse restaurants, and the number of hotel guests, from the Regional Economic and Social Analysis System (V-RESAS). Two waves of COVID-19 infections were examined using cross-correlation analysis. In the first wave, all four indicators of going out changed to be opposite the change in new PCR positive cases, showing a lag period of –1 to +6 weeks. In the second wave, the same relationship was only observed for the index of web searches for going outside, and two indicators showed the positive lag period of +6 to +12 weeks after the change in new PCR positive cases. Moreover, each indicator in the second wave changed differently compared to the first wave. The complexity of people’s behaviors around going out increased in the second wave, when policies and campaigns were implemented and people’s attitudes were thought to have changed. In conclusion, the results suggest that policies may have influenced people’s mobility, rather than the number of new PCR positive cases.

Ultrasound is a convenient non-invasive imaging modality used for the diagnosis or detection of various diseases and assessment of therapeutic effects. However, when imaging internal organs, the ultrasound probe must be handled by an operator. The ability to perform hands-free ultrasound imaging of internal organs is likely to offer an unprecedented advantage in various situations such as internal organ monitoring during exercise tests and prolonged monitoring. Toward this end, we have developed a new method of hands-free monitoring using three-dimensional (3D) ultrasound and used this method in portal vein monitoring, which is important for functional evaluation of hepatic and gastrointestinal systems. In previous studies, we developed a handmade probe holder and used it to capture images of the portal vein, using image tracking and registration to compare the same position of the portal vein. In this study, we rst used an abdomen phantom to assess image tracking qualitatively and quantitatively. After validating the method on the phantom, we monitored the portal vein in three healthy subjects using our 3D ultrasound method. Image tracking and registration of the portal veins in three subjects were successfully performed of ine. Finally, respiratory analysis and vein diameter measurement were performed based on the image tracking results. The respiratory analysis quanti ed the respiration-induced portal vein movements. The vein diameter showed changes that might be induced by respiration and heartbeat. These results indicate that our 3D ultrasound method is a potentially useful tool for handsfree monitoring of internal organs.

Suppression of the first wave of COVID-19 in Japan is assumedly attributable to people's increased risk perception by acquiring information from the government and media reports. In this study, going out in public amidst the spread of COVID-19 infections was investigated by examining new polymerase chain reaction (PCR) positive cases of COVID-19 and its relationship to four indicators of people going out in public (the people flow, the index of web searches for going outside, the number of times people browse restaurants, and the number of hotel guests), from the Regional Economic and Social Analysis System (V-RESAS). Two waves of COVID-19 infections were examined with cross-correlation analysis. In the first wave, all four indicators of going out reacted oppositely with the change in new PCR positive cases, showing a lag period of -1 to +6 weeks. In the second wave, the same relationship was only observed for the index of web searches for going outside. These results suggest that going out in public could not be described by new PCR positive cases alone in the second wave, even though they could explain people going out to some extent in the first wave.