Cluster Analysis and Discriminant Analysis for Determining Post-Earthquake Road Recovery Patterns.

The transport network in eastern Japan was severely damaged by the 2011 Tohoku earthquake. To understand the road recovery conditions after a large earthquake, a large amount of time is needed to collect information on the extent of the damage and road usage. In our previous study, we applied cluster analysis to analyze the data on driving vehicles in Fukushima prefecture to classify the road recovery conditions among municipalities within the first six months after the earthquake. However, the results of the cluster analysis and relevant factors affecting road recovery from that study were not validated. In this study, we proposed a framework for determining post-earthquake road recovery patterns and validated the cluster analysis results by using discriminant analysis and observing them on a map to identify their common characteristics. In addition, our analysis of objective data reflecting regional characteristics showed that the road recovery conditions were similar according to the topography and the importance of roads.

False positive results in severe acute respiratory coronavirus 2 (SARS-CoV-2) rapid antigen tests for inpatients.

Severe acute respiratory syndrome coronavirus 2 rapid antigen detection (RAD) test kits are widely used as primary screening test in Japan because rapid diagnosis of coronavirus disease 2019 (COVID-19) is critical for infection control. We report cases with RAD test false-positive results in a ward for patients with disabilities. RAD tests potentially evoke hospital operational risk. It is desirable that performing PCR test appropriately when patients admitted to a medical treatment ward with COVID-19 symptoms instead of RAD test.

Removal of organic pollutants and metabolic adaptation of microorganisms by micro-aeration.

Aerobic systems are high rate processes for wastewater treatment, but they consume much power for aeration. Several low-cost anaerobic systems have been developed for mid- and low-income countries. The removal efficiencies of nutrients, particulate matter, and pathogens are not satisfactory for the anaerobic systems. Micro-aeration is a type of low-cost aerobic application which enhances oxygen transfer through water surface. Trickling was found the most efficient method of micro-aeration and batch experiments were performed to evaluate the effectiveness. When soluble organic carbon was removed, ORP7 (redox potential rectified to pH at 7) were around -120 or +260 mV. When soluble organic carbon increased due to organic overload, ORP7 was around +30 mV. At +30 mV, carbon fraction of biomass increased to 0.54 (higher than average value of 0.46). It was presumable that the ORP7 of -120, +260, and +30 mV were anaerobic, aerobic, and internal storage mode, respectively. Maximum reaction rate of aerobic condition was four times as high as that of anaerobic condition. At internal storage mode, the rate was halved from aerobic mode. It is concluded that microorganisms adapt the metabolic systems to conform to the redox environment, which can be evaluated by ORP. Organic overload results metabolic shift to internal storage mode which retards mineralization of organic matter.