Kenju Akai’s research while affiliated with Shimane University and other places

Objective Few studies have detailed the physical activity and postural patterns (e.g. lying or sitting) in older adults with declining activities of daily living (ADL). Therefore, we aimed to address this issue by quantifying physical activity using an accelerometer and measuring time spent in various postures among older adults in assisted-living residences. Methods We quantified physical activity using an accelerometer (ActivPAL) and measured time spent in various postures in 35 older adults (mean age: 89.1 years) with chronic conditions residing in two assisted-living residences in Japan. ActivPAL was attached to the thigh and trunk of patients to distinguish between sitting and lying postures. Results Participants had a mean count of 6.2 comorbidities, and they were divided into three groups (fully independent, requiring minimal assistance and requiring care) based on their activities of daily living capacity using the Barthel Index. Residents aged ⩾90 years walked a mean of 1109.1 steps and spent 167.3 min upright per day. Fully independent participants walked a mean of 3587.6 steps daily; those requiring minimal assistance walked 1681.0 steps daily; and those requiring care walked 428.9 steps daily. Conclusions Our findings indicated that step count, number of sit-to-stand transitions, stepping time, and upright time decreased significantly as activities of daily living capacity decreased. Comorbidity type and number of comorbidities were not related to their lying time except for depression status. Lying time was associated with depression status.

This study evaluates the interdependence between pricing and expectations. We investigated not only the ways in which traders’ thoughts determined asset prices, but also the feedback process from prices to expectations. In our laboratory market, subjects were asked to estimate the number of balls in a jar and trade an asset whose value was equal to that number. Our asset market, where transactions were eventually settled at the asset value, was like futures markets. The subjects alternately repeated the process of guessing and transaction. A double-auction was used to design our market. Our findings indicated a downward bias in the subjects’ estimates, which led to lower transaction prices, since the price converged to the equilibrium price that was determined by the median of estimates. The subjects’ experience in our laboratory markets had no systematic effect on the accuracy of estimates, but made them less heterogenous. Our subjects were apt to revise their estimates with reference to prices in a market. We examined the estimation revision process of the subjects using the partial adjustment model.

In this study, the consumer value of strawberries in Spain and Japan based on sensory output and sustainable input attributes was investigated using a choice experiment. The choice set consisted of five attributes—price, color, taste, cultivation method, and energy source for greenhouse cultivation. This study recruited 1,000 respondents each in Spain and Japan to complete an online survey. Japanese respondents preferred strawberries that were red, sweet, organic, cultivated with solar or woody biomass-generated power, and cheap. In addition to these attributes, Spanish respondents preferred less sour strawberries. Spanish respondents exhibited a greater willingness-to-pay (WTP) for both organic and renewable energy inputs than Japanese respondents. For both nationalities, the WTP for renewable energy was higher than that for the taste scale attribute but lower than the color attribute. Spain had a higher WTP for solar and woody biomass energies than Japan. There was no significant difference in the WTP for white and pink colored strawberries between the two. Spain had a higher WTP for organic cultivation than Japan. In both countries, consumers were more averse to the pink strawberry when the cultivation used solar energy rather than kerosene. In both countries, there was an additive effect for woody biomass and sweetness, but a moderate effect for sour taste. These results imply that renewable energy input has a significant effect on consumer choice for strawberries without tasting. Thus, these results should motivate strawberry farmers to cultivate strawberries using renewable energy in greenhouses to help reduce the effects of climate change; thereby, increasing the value of strawberries.

This study investigates “hypothetical bias,” defined as the difference in the willingness to pay for a product attribute between hypothetical and non-hypothetical conditions in a choice experiment, for the carbon footprint of mandarin oranges in Japan. We conducted the following four treatments: a non-hypothetical lab economic experiment, a hypothetical lab survey, a hypothetical online survey, and a hypothetical online survey with cheap-talk. Each treatment asked participants to choose one of three oranges based on price and carbon emissions level. Next, participants were asked to answer questions on demographics and the following three kinds of environmental factors: environmental consciousness, purchasing behavior for goods with eco-labels, and daily environmental behavior. Using the random parameter logit model, the willingness to pay per 1g of carbon emission reduction were 0.53 JPY, 0.52 JPY, 0.54 JPY, and 0.58 JPY in the non-hypothetical lab economic experiment, hypothetical lab survey, hypothetical online survey and hypothetical online survey with cheap-talk, respectively. The complete combinatorial test of the willingness to pay for carbon emission reductions indicates no hypothetical bias between any treatment combinations. Our findings reveal that environmental attributes for food are less likely to show hypothetical bias than other goods. The results of the main effect with an interaction term show that environmental consciousness reduces the coefficients of carbon emissions in all treatments. Therefore, a psychological scale is useful for showing whether hypothetical bias emerges with treatment or participants’ personal backgrounds.

This study aims to investigate the need to improve parking facilities at Japan’s Izumo Airport. The occupancy of on-site parking lots was analyzed using one-day, weekend, and long-term parking metadata, and passengers passing through the security gate were surveyed on their satisfaction with airport parking. More than 4,000 passengers were recruited for the survey, of whom over 1,000 passengers who drove a car were asked about their satisfaction with the number and size of the parking lots available, the space for vehicle traffic, and the pedestrian walkway to the terminal. Additionally, they answered questions regarding necessary parking lot improvements and if it was better to expand the parking space or charge fees for it. The occupancy metadata analysis found that parking lots near the terminal buildings were almost full, whereas those farther away were comparatively unoccupied. The ordered logit estimation results for satisfaction showed that older respondents, those who parked far away from the terminal building, and those who took morning flights had significantly negative satisfaction levels. Similar estimation results for parking services improvement showed that users dissatisfied with the number of parking lots wanted improved parking services and preferred parking space expansion over a new fee. The combination study of metadata and satisfaction survey sheds new light on occupancy asymmetry, which contributes the most to the dissatisfaction over the number of parking lots. Therefore, smoothing occupancy and traffic trajectories between these areas is key to improving drivers’ satisfaction.

Sarcopenia is intricately related to aging associated diseases, such as neuropsychiatric disorders, oral status, and chronic diseases. Dementia and depression are interconnected and also related to sarcopenia. The preliminary shift from robust to sarcopenia (i.e., pre-sarcopenia) is an important albeit underdiscussed stage and is the focus of this study. Identifying factors associated with pre-sarcopenia may lead to sarcopenia prevention. To separately examine the effects of dementia and depression on pre-sarcopenia/sarcopenia, we conducted multiple analyses. This cross-sectional study used health checkup data from a rural Japanese island. The participants were aged 60 years and above, and the data included muscle mass, gait speed, handgrip strength, oral status (teeth and denture), chronic diseases (e.g., hypertension), dementia (cognitive assessment for dementia, iPad Version), and depression (self-rating depression scale). A total of 753 older adult participants were divided into the sarcopenia (n = 30), pre-sarcopenia (n = 125), and robust (n = 598) groups. An ordered logit regression analysis indicated that age and depression were positively correlated with sarcopenia, while hypertension was negatively associated with it. A multiple logistic regression analysis between the robust and pre-sarcopenia groups showed significant associations between the same three variables. Depression was associated with pre-sarcopenia, but not dementia. There was also a significant association between hypertension and pre-sarcopenia. Further research is needed to reveal whether the management of these factors can prevent sarcopenia.