Tokyo Research Articles

Quantifying the impact of earthquakes on urban energy consumption and carbon emissions in Tokyo from a nexus perspective

Unexpected events can have profound impacts on urban resource supply and consumption. The Great East Japan Earthquake (3.11 hereafter) triggered not only the planned blackout in the Tokyo Metropolitan Region soon after the disaster but also the energy shift to fossil fuels to recover from the disfunction of Fukushima nuclear power plants. Previous research has mainly focused on the direct energy consumption and carbon emissions of different sectors while the intensity and extensity of the impact on industries and the environment have never been empirically addressed. This study explores energy-use efficiency and carbon emissions in Tokyo from 2011 to 2015 through a lens of nexus using environmentally extended input-output analysis and community-wide carbon analytic approaches. Results show that the energy consumption is the largest exporter and importer of carbon emissions, whereas energy losses and carbon emissions caused by energy conversion and transmission are almost twice as much as those caused by the direct parts. Strong nexus effects among building and material, transportation, and energy consumption were observed. The 3.11 greatly impacted the energy structure and carbon emission patterns because of the increased consumption of coal for electricity. The share of energy consumption and carbon emissions by raw materials for construction also increased because of the increased demand for the reparation and reconstruction of buildings and transport systems. This structural change provided new scientific evidence for governments to implement decarbonization policies while preparing for unprecedented events.

Application of the Ocean Health Index to assess ocean and coastal conditions of the Tokyo Metropolitan area

Ocean ecosystem services are fundamental to coastal economic development and climate regulation. The Tokyo Metropolitan Area (TMA) is one of the world’s most significant bay areas, with its economic development and residents relying on a healthy ocean and diverse marine ecosystem services. Post-World War II, the coastal zones of TMA have suffered from various human-induced stresses and impacts, jeopardizing the capacity of ocean ecosystem services and sustainable development. Although recent years have seen improvements in basic marine water quality, other ecosystem health issue, such as biodiversity, carbon storage, coastal protection are remain limited and require comprehensive enhancement. To better understand the current state of ocean health, promote more comprehensive ocean management decisions and plans, and support sustainable development in the region, it is essential to evaluate the ocean’s condition in the TMA and to assess future trends and risks. The Ocean Health Index (OHI) offers a comprehensive framework to evaluate global and regional ocean health conditions and their ecosystem services. This study applies the OHI to assess the ocean and coastal health of TMA, with indicators and reference points adjusted based on local conditions. From 2014 to 2019, the OHI assessment results indicate that TMA obtained an overall OHI score of 49 (out of 100), with goals ranging from 13 to 87. The environmental and social goals, such as Tourism and Recreation (87), Clean Water (67), Coastal Livelihoods and Economies (62), Sense of Place (62), and Artisanal Fishery Opportunity (51), are relatively high. In contrast, the ecological goals, such as Biodiversity (14), Carbon Storage (13), Coastal Protection (38), and Food Provision (24), are relatively low. This case study highlights strategies for improving ocean health conditions in TMA from both OHI goals and management structure perspectives. The methods and results provide a quantitative tool for regional marine and coastal management in TMA, aiding regional management organizations to establish quantifiable objectives for actions that were previously difficult to quantify. These results can indirectly promote the establishment of more comprehensive and holistic regional management organizations in TMA, which is currently fragmented, thereby effectively enhancing ocean health in TMA.

Urban dynamics and their implication on greenness trends: A 25-year retrospective study of the changing face of tokyo metropolitan area

Global metropolises and their needs for green space are rising due to demographic urbanization. Some phenomena contradicted to prevailing understanding have been observed in metropolises, such as the “sprawl shrinkage” associated with the increasing built-up area despite declining populations, and the positive relationship between population and greenness. To study these storylines, we conceptualized and mapped 5 urban dynamics by cross-referencing the“increase, stable, and decrease”of built-up area and population density based on threshold values of an introduced Normalized Difference Index (NDI). Furthermore, Kruskal-Wallis H Test was used to analyze the influence of different urban dynamic patterns on 3 greenness trends (greening, browning, and stable greenspace). From 1995 to 2021, Tokyo Metropolitan Area (TMA) gradually transited from intense urban expansion to a stabilization of built-up area and population density in the city center, declining urbanization in the peri-urban areas, and “sprawl shrinkage” in the far-outskirts. Moreover, compared to other urban dynamics, the pattern of built-up areas increases with a population density reduction of over 5% were conducive to maintaining NDVI values of 0.75 or higher. In the future, the ongoing demographic urbanization is highly likely to further exacerbate the phenomenon of urban-suburban disparity and intra-suburban differentiation. We propose that Asian metropolises should enhance regional cooperation and public-private partnerships to address potential regional ecological imbalances. Additionally, it is necessary to maximize the greenness within the given urban dynamics through figuring out the spatial impact mechanisms of urban development on greenness change from a long-term perspective.

Aging trajectories of subscales in higher-level functional capacity among community-dwelling older Japanese adults: the Otassha study

BackgroundMaintaining higher-level functional capacity is important for independent living in older age. The aging trajectory of the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC) has three patterns; however, the subscale patterns are unclear.AimsThis study aimed to clarify the aging trajectory patterns of the TMIG-IC subscales among community-dwelling older Japanese.MethodsParticipants were 3,169 community-dwelling older Japanese who participated in the 2012–2022 mail survey of the Otassha study. The aging trajectory patterns of the TMIG-IC total and subscale scores for those aged 65–90 years were identified using group-based trajectory modeling. Further, the combination frequency of the subscale trajectory patterns was determined.ResultsThree patterns were identified: early-onset decreasing, late-onset decreasing, and high-stable.DiscussionThe instrumental activities of daily living (IADL) trajectory was maintained until approximately 80 years of age; however, chronic disease prevailed the most in the early-onset decreasing pattern. The early-onset decreasing pattern of intellectual activity (IA) was present in 25% of participants, showing impaired IA from 65 years of age. The late-onset decreasing pattern of social roles (SR) was present in 30% of participants, showing a sharp decline compared to other subscales. For many people, the patterns of decrease in SR and IA overlapped.ConclusionsTo maintain higher-level functional capacity, interventions that include disease management and prevention of decline in IADL and increase the awareness of the social support provided throughout old age and interventions for people with an early decline in IA should be implemented.

Combination of 2 test methods, single-picture optotype visual acuity chart and spot™ vision screener, in the eye health screening program for 3-year-old children in Tokyo: A retrospective, observational study.

To evaluate the usefulness of the Tokyo Metropolitan Government's Eye Health Screening Program for 3-year-old children, which combines the Single-Picture Optotype Visual Acuity Chart (SPVAC) and Spot™ Vision Screener (SVS) tests. This was a retrospective, observational, matched study. Patients who underwent the eye health screening program and had abnormalities were classified into 3 groups according to the outcomes of the SPVAC (SPVAC-passed, SPVAC-P; SPVAC-failed, SPVAC-F) and SVS (SVS-passed, SVS-P; SVS-failed, SVS-F) tests as follows: SPVAC-P/SVS-F, SPVAC-F/SVS-P, and SPVAC-F/SVS-F. We evaluated the age at examination, SPVAC and SVS test success rates, and SVS refractive power. Additionally, the rates of refractive error, amblyopia, and strabismus were compared among the 3 groups. The SPVAC-P/SVS-F, SPVAC-F/SVS-P, and SPVAC-F/SVS-F groups comprised 158, 28, and 74 eyes, respectively. The mean age was 37.4 months. The success rates of the SPVAC and SVS tests were 69.8% and 96.2%, respectively. The mean SVS hyperopia value in the SPVAC-F/SVS-F group (2.71 ± 1.50 D) was significantly higher than that of the SPVAC-P/SVS-F group. The mean SVS astigmatism and myopia values were -2.21 diopter (D) ± 1.09 D and -3.40 ± 1.82 D, respectively; they did not differ significantly from that of the SPVAC-P/SVS-F group. Significant differences were observed in the refractive error, amblyopia, and strabismus rates among the 3 groups. Regarding disease determination, no significant difference was observed among participants who passed and failed the SPVAC test, regardless of the outcome of the other test. However, a significant difference was observed between those passing and failing the SVS tests. The SPVAC method used to screen 3-year-old children should be modified to commence at 42 months of age or be replaced with a single Landolt C test. The SVS test is useful for screening younger patients. Furthermore, the SVS test showed that the degree of hyperopia was higher in patients who did not pass the SPVAC test.

A Cross-Sectional Study on Whether Comprehensively Gathering Information From Medical Records Is Useful for the Collection of Operational Characteristics.

This study tests whether comprehensively gathering information from medical records is useful for developing clinical decision support systems using Bayes' theorem. Using a single-center cross-sectional study, we retrospectively extracted medical records of 270 patients aged ≥16 years who visited the emergency room at the Tokyo Metropolitan Tama Medical Center with a chief complaint of experiencing headaches. The medical records of cases were analyzed in this study. We manually extracted diagnoses, unique keywords, and annotated keywords, classifying them as either positive or negative. Cross tables were created, and the proportion of combinations for which the likelihood ratios could be calculated was evaluated. Probability functions for the appearance of new unique keywords were modeled, and theoretical values were calculated. We extracted 623 unique keywords, 26 diagnoses, and 6,904 annotated keywords. Likelihood ratios could be calculated only for 276 combinations (1.70%), of which 24 (0.15%) exhibited significant differences. The power function+constant was the best fit for new unique keywords. The increase in the number of combinations after increasing the number of cases indicated that while it is theoretically possible to comprehensively gather information from medical records in this way, doing so presents difficulties related to human costs. It also does not necessarily solve the fundamental issues with medical informatics or with developing clinical decision support systems. Therefore, we recommend using methods other than comprehensive information gathering with Bayes' theorem as the classifier to develop such systems.

Research Group Introduction: Abe Laboratory, Electrical and Electronics Engineering Program, Dept. of Monozukuri Engineering, Tokyo Metropolitan College of Industrial Technology

Research Group Introduction: Abe Laboratory, Electrical and Electronics Engineering Program, Dept. of Monozukuri Engineering, Tokyo Metropolitan College of Industrial Technology

Hydrogeochemistry of unconfined groundwater along the flowpaths on Musashino Uplands, Tokyo Metropolitan

Hydrogeochemistry of unconfined groundwater along the flowpaths on Musashino Uplands, Tokyo Metropolitan

An in-person survey of the influence of the COVID-19 pandemic on physical function, functional capacity, cognitive function, and mental health among community-dwelling older adults in Japan from 2016 to 2022

BackgroundThe COVID-19 outbreak might have had several effects on older adults; however, much of the previous research only included self-report, cross-sectional, and online-survey data in the early stage of the pandemic. We conducted a face-to-face survey before and after the COVID-19 pandemic and investigated the influence of the pandemic on several functions to distinguish between changes due to aging and changes due to the pandemic using a linear mixed model.MethodsA total of 8 longitudinal surveys were conducted from 2016 to 2022. Physical function was assessed by weight, body mass index, body fat percentage, skeletal muscle mass index, calf circumference, grip strength, knee extension strength, the 5-times chair stand test, the timed up & go test and 5-m walking test. Functional capacity was measured using the Tokyo Metropolitan Institute of Gerontology index of competence, cognitive function was measured using the Trail Making Test - A, and mental health was measured using the Geriatric Depression Scale.ResultsOf a total of 73 participants, 51 (69.9%) were female. The mean age at first participation was 71.82 years (SD = 4.64). The results of the linear mixed model showed that lower-limb muscle strength and body fat percentage and cognitive function changed significantly before and after the pandemic, while grip strength, functional capacity, and mental health did not.ConclusionsThe changes in these functions between before and after the pandemic might be attributed to the diminished opportunities for the independent older individuals to go out and engage in activities. Although functional capacity did not change, lower-limb muscle strength is important for functional independence. This decline might influence the functional capacity of these individuals in the future.

Role of Individual Social Capital in the Association of Physical Frailty With Functional Ability Among Older Adults

ObjectivesRich social capital is regarded as an individual's social asset, which may contribute to the maintenance of functional ability, even in a state of frailty. This study examined the moderating role of individual social capital in the association between physical frailty and functional ability among older adults. DesignA cross-sectional study. Setting and ParticipantsIn total, 522 community-dwelling older adults aged ≥60 years were recruited from among visitors to public facilities, including community cultural centers and gymnasiums in Aichi, Japan. MethodsFunctional ability was assessed using the 5-item subscale of the Tokyo Metropolitan Institute of Gerontology Index of Competence that assesses instrumental self-maintenance, including transportation, finance management, and shopping. Physical frailty was defined by the Fried Frailty Phenotype Questionnaire, including 5 items of fatigue, resistance, ambulation, inactivity, and weight loss, and the participants were classified into 3 groups: non-frailty, pre-frailty, and frailty. Individual social capital was assessed for 2 dimensions: the cognitive dimension (perceptions of community social cohesion) and the structural dimension (informal socializing and social participation). ResultsThe participants’ mean age (SD) was 74.1 (6.5) years and 78.0% were women. Among the participants, non-frailty was 46.6%, pre-frailty was 47.0%, and frailty was 6.5%. Multivariable linear regression analysis revealed that physical frailty was associated with lower levels of functional ability compared with non-frailty [pre-frailty: β (95% CI) = −0.07 (−0.22 to 0.08), P = .374; frailty: β = −0.67 (−0.99 to −0.35), P < .001]. However, individual structural social capital showed a negative interaction with physical frailty against low functional ability, indicating a moderating association (P = .027). Conclusions and ImplicationsHigh levels of individual structural social capital mitigated the adverse association between physical frailty and functional ability. Fostering rich social capital may preserve the functional ability of frail older adults, helping their independent lives in the community.

A Comparative Evaluation of Arginine Complex Combined With Flouride and Two Standard Non-Fluoridated Remineralizing Agents: An In Vitro Study.

Background Dental caries represents a dynamic process, often reversible in its early stages. Fluoride has conventionally served as the cornerstone for remineralization and early caries arrest. However, excessive fluoride intake can lead to both local and systemic toxicity. Hence, there's a pressing need to develop adjunct therapies that enhance fluoride's efficacy while minimizing its dosage. This study aims to assess and compare the remineralization potential of a novel combination comprising arginine bicarbonate and fluoride against established technologies such as Bioactive glass (NovaMin Technology; Sensodyne Repair and Protect, GlaxoSmithKline, UK) and CPP-ACP technology (GC Tooth Mousse; Tokyo Japan). Materials and methods The experiment utilized extracted premolars designated for orthodontic extraction. The initial evaluation employed the DIAGNOdentTMfluorescence method. Subsequently, teeth underwent demineralization and were measured for values. Following this, the teeth were subjected to seven cycles of remineralization, after which moment values were reassessed. Statistical analysis was performed on the recorded values. Results Participants were divided into six groups (BR-A, AR-A, BR-B, AR-B, BR-C, AR-C). T-tests demonstrated significant reductions in moment values within each group, indicating the effectiveness of all remineralizing agents. Group C exhibited the most substantial difference (-6.900 ± 0.4), followed by Group A and Group B. ANOVA analysis revealed statistically significant differences among all three groups (p=0.016). Tables showed significant distinctions between the remineralizing values of Groups A and C and Groups B and C (p=0.02 and 0.002, respectively), with no discernible distinction between Groups A and B. Conclusion The study elucidates the superior efficacy of the arginine complex with fluoride combination compared to CPP-ACP and Bioactive Glass individually. This finding underscores the potential of the novel combination therapy in enhancing remineralization while minimizing fluoride dosage, thus presenting a promising strategy for addressing early-stage dental caries.

Research on the Relationship Between Urban and Traffic Environments and Health Among Returning Drivers of Drivers’ Licenses

This study sought to determine the relationship between urban and transportation environments and health among older adults who have returned their driver’s licenses. Many elderly people who have given up their driver’s license consider it a good thing. The reasons given were that they no longer had to worry about causing traffic crashes and the stress of driving. Factors that influenced whether or not they were glad to give up their driver’s license included the shift in transportation from driving to walking, and the health benefits of walking. Returning one’s driver’s license at the appropriate time may contribute to the health of elderly people. The health status of elderly people was assessed using the Tokyo Metropolitan Institute of Gerontology Index of Competence and a frailty index. Structural equation modeling was used to structure the relationship between the urban and transportation environment and health of elderly people who had given up their driver’s licenses. The results showed that the layout of facilities (e.g., supermarkets, hospitals, and bus stops) around the home influenced the age at which the driver’s license was returned. It was also shown that the younger the age of returning the motor vehicle driver’s license, the less frailty and the higher activity capacity was experienced by individuals. This may be because returning a driver’s license at an earlier age makes it easier to adjust to a new life and to new modes of transportation.

Sodium removal per ultrafiltration volume in automated peritoneal dialysis in pediatric patients.

The standard rate of sodium removal in adult anuric patients on continuous ambulatory peritoneal dialysis (CAPD) is 7.5g/L of ultrafiltration volume (UFV). Although automated PD (APD) is widely used in pediatric patients, no attempt has yet been made to estimate sodium removal in APD. The present, retrospective cohort study included pediatric patients with APD who were managed at Tokyo Metropolitan Children's Medical Center between July 2010 and November 2017. The patients underwent a peritoneal equilibrium test (PET) at our hospital. Sodium removal per UFV was calculated by peritoneal function and dwell time using samples from patients on APD with 1- and 2-h dwell effluent within three months of PET and 4- and 10-h dwell effluent at PET. In total, 217 samples from 18 patients were included, with 63, 81, and 73 of the samples corresponding to the High [H], High-average [HA], and Low-average [LA] PET category, respectively. Sodium removal per UFV (g/L in salt equivalent) for dwell times of one, two, four, and ten hours was 5.2, 8.8, 8.0, and 11.5 for PET [H], 5.3, 5.8, 5.6, and 8.1 for PET [HA], and 4.6, 5.1, 5.1, and 7.1 for PET [LA], respectively. Sodium removal per UFV in pediatric APD was less than the standard adult CAPD and tended to be lower with shorter dwell times, leading to sodium accumulation. Therefore, salt intake should be restricted in combination with one or more long daytime dwells, especially in anuric patients.

Effects of a dementia educational programme using virtual reality on nurses in an acute care hospital: A pre-post comparative study.

Poor awareness of dementia care by healthcare professionals affects the quality of care for people living with dementia in acute care settings. This study examined the effectiveness of a virtual reality-based educational programme for dementia for nurses working in acute care hospitals in Japan. A dementia education programme for nurses was designed. The programme comprised short movies, virtual reality videos based on the short movies, a lecture, discussions and role-playing based on the experimental learning model. Virtual reality video content was created to promote empathy for people living with dementia through a first-person experience of dementia. The educational programme involved nurses working in an acute care hospital in the Tokyo Metropolitan area. Before and after the programme, we employed structured questionnaires using validated instruments to assess participants' attitudes towards people living with dementia, their intentions of helping behaviour and their confidence in providing dementia care. Seventy-six nurses participated in and completed the pre- and post-tests. The mean age was 34.9 ± 9.2 years, and 90.8% of the participants were female. A paired t-test showed significant before-after improvement in the participants' attitudes towards people living with dementia (41.9 ± 5.1 vs. 44.5 ± 4.8), intentions of helping behaviour towards people living with dementia (10.8 ± 2.5 vs. 12.8 ± 2.1) and confidence in providing dementia care (25.9 ± 6.7 vs. 29.2 ± 6.0). The programme effectively improved nurses' attitudes towards people living with dementia and confidence in providing dementia care in acute care settings. Future research is important to explore the long-term effects of this programme and its effects on actual dementia care. The dementia education programme may promote person-centred care in acute hospitals. Future studies should consider the provision of more flexible programs so that nurses can more easily participate in them.

관동대지진과 ‘유언비어’

This paper is an attempt to examine the use of “rumors” in the national narrative of the massacre of Koreans during the Great Kanto Earthquake. It is important to note that “rumor” is a term that is judged ex post facto and that from the perspective of security forces, “rumor” is a target for cracking down on, so this paper argues that it is necessary to distinguish between the period before and after the security forces perceived information about Koreans as “rumors”. Therefore, this paper analyzes the “rumor” records of Taisho Daishinkasaishi by the Tokyo Metropolitan Police Department (1925) as the records after the security forces perceived “rumors,” ex post facto records. To reveal the intended use of “rumors” selected, revised, and manipulated by the Tokyo Metropolitan Police Department, I trace the primary sources of the “rumor” records in Taisho Daishinkasaishi and contrast them with those sources to show that “rumor” records have a political agenda. This attempt may contribute to emphasizing the importance of verifying the historical account of the Great Kanto Earthquake as portrayed by official documents and government publications.

Difficulty experienced by family in supporting elderly diabetic patients is associated with a decline in patients' higher-level functions

To examine the relationship between difficulties experienced by family in supporting elderly patients with diabetes and these patients' higher-level functions. The subjects were outpatients with diabetes ≥65 years old at Ise Red Cross Hospital and their family members. The Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC) was used to assess patients' higher-level functions. The Japanese version of the Diabetes Caregiver Activity and Support Scale (D-CASS-J) was used to measure difficulties experienced by family in supporting elderly patients with diabetes. Using a multiple regression analysis with TMIG-IC scores (instrumental ADL, intellectual activity, and social participation) as the dependent variable and D-CASS-J scores (based on the highest scoring Q1 group among the three quartiles of D-CASS-J scores) as the explanatory variables, standardized regression coefficients (β) for higher-level functions on the family's perceived support difficulties were calculated. In total, 429 patients (254 male patients and 175 female patients) were included in the analysis. For male patients, the adjusted beta values for TMIG-IC scores in Q2 and Q3 were -0.039 (P=0.649) and -0.352 (P<0.001), respectively, and the adjusted beta values for the instrumental ADL scores were -0.064 (P=0.455), -0.192 (P=0.047), -0.090 (P=0.375), and -0.360 (P=0.002) for the Intellectually Active scores, respectively, and the adjusted beta for social role scores were 0.054 (P=0.581) and -0.261 (P=0.019), respectively. However, there was no association between the patients' higher-level functions and family support difficulties among female patients. Difficulty experienced by the family in supporting elderly male patients with diabetes is associated with reduced higher-level functioning.

Three species of the family Aoridae Stebbing, 1899 (Crustacea: Amphipoda) collected from remote islands in southern Japan, with a key to all Japanese species of the family

Three species of the aorid amphipod were collected from remote islands in southern Japan. Protolembos ryukyuensis sp. nov. was collected from Ishigaki Island in Okinawa Prefecture and Tanegashima Island in Kagoshima Prefecture, and characterized by the dense plumose setae on the male gnathopods 1 and 2. Tethylembos cavatus sp. nov. and T. japonicus Ariyama, 2004 were collected from Miyake Island and the Ogasawara Islands in Tokyo Prefecture, respectively. Both species share the male gnathopod 1 propodus heavily setose medially; however, Tethylembos cavatus can be distinguished from T. japonicus in the excavated basis of the male pereopod 5. Keys to species of Protolembos Myers, 1988 and Tethylembos Myers, 1988 in the world and a key to all Japanese species of the family Aoridae are provided. Number of aorid species in Japan stands at 34.

Karakteristik Penanda Kohesi Gramatikal dan Kohesi Leksikal Pada Wacana Iklan Kosmetik Kecantikan Wajah Jepang

The purpose of this research is to explain the relationship between grammatical cohesion markers and lexical cohesion in advertising discourse that can support the formation of coherence. The data used comes from the Canmake Tokyo Japan advertisement. The data collection method used is the listening method with the basic technique, namely the tapping technique and the note-taking technique as a follow-up technique. The data analysis stage uses the commensurate method with the technique of sorting the determining elements (PUP). While the results of data analysis are presented using informal methods. Based on the results of data analysis, it can be seen that the cosmetic advertisements from Canmake Tokyo contain grammatical cohesion markers and lexical cohesion. Based on the appropriate use of cohesion markers, it can be seen that the discourse of Canmake Tokyo cosmetic advertisements is a discourse of coherence. The most common grammatical cohesion markers are reference and conjunction. While the most lexical cohesion markers found are repetition and synonyms.

Lognormal distribution of daily travel time and a utility model for its emergence

Understanding the nature of human movement is important in many fields, such as transportation management, urban planning, and epidemiology. In this study, we focus on travelers who are grouped by their travel modes in the Tokyo Metropolitan Area. Notably, for each group of travelers, the distribution of daily travel time follows a lognormal distribution. For any travel mode, the distributions of normalized travel time for different years (1968–2008) and distances to the city center converge to a curve, although the average travel time and share of travel modes vary. By employing the concept of utility, we developed a disaggregate model wherein an individual maximizes utility from traveling (=benefit - cost) by modifying daily travel time. This model theoretically explained the observed distributions of travel time. The model was further used to demonstrate travel mode choices. The model parameters were estimated using the distribution of travel time, travel mode share, and manageable assumptions. These results provided interesting interpretations of the perceptual utility of the daily travel time of a population. Moreover, the obtained curves of utility versus time are similar to the shapes of the overall benefits assumed in previous studies. Overall benefit is a concept that has been developed and examined since the 1980s, and our study provides a mathematical foundation for this idea.

Heterogeneous Association of Tooth Loss with Functional Limitations

Tooth loss is prevalent in older adults and associated with functional capacity decline. Studies on the susceptibility of some individuals to the effects of tooth loss are lacking. This study aimed to investigate the heterogeneity of the association between tooth loss and higher-level functional capacity in older Japanese individuals employing a machine learning approach. This is a prospective cohort study using the data of adults aged ≥65 y in Japan (N = 16,553). Higher-level functional capacity, comprising instrumental independence, intellectual activity, and social role, was evaluated using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC). The scale ranged from 0 (lowest function) to 13 (highest function). Doubly robust targeted maximum likelihood estimation was used to estimate the population-average association between tooth loss (having <20 natural teeth) and TMIG-IC total score after 6 y. The heterogeneity of the association was evaluated by estimating conditional average treatment effects (CATEs) using the causal forest algorithm. The result showed that tooth loss was statistically significantly associated with lower TMIG-IC total scores (population-average effect: −0.14; 95% confidence interval, −0.18 to −0.09). The causal forest analysis revealed the heterogeneous associations between tooth loss and lower TMIG-IC total score after 6 y (median of estimated CATEs = −0.13; interquartile range = 0.12). The high-impact subgroup (i.e., individuals with estimated CATEs of the bottom 10%) were significantly more likely to be older and male, had a lower socioeconomic status, did not have a partner, and had poor health conditions compared with the low-impact subgroup (i.e., individuals with estimated CATEs of the top 10%). This study found that heterogeneity exists in the association between tooth loss and lower scores on functional capacity. Implementing tooth loss prevention policy and clinical measures, especially among vulnerable subpopulations significantly affected by tooth loss, may reduce its burden more effectively.