title: Three studies on life expectancy and lifespan inequality

authors: Wijesinghe, Jayani

abstract: While life expectancy is a key indicator in public health and demography, it may obscure unequal experiences of different population groups. By contrast, lifespan inequality captures variations in age at death, offering a broader view of health disparities. Focusing on lifespan inequality enables policymakers and researchers to identify vulnerable populations, design more equitable health and social policies, and evaluate progress toward reducing inequities. 
This thesis is comprised of three interrelated studies that examine life expectancy and lifespan inequality from different perspectives. The first study explores state-level variations in life expectancy and lifespan inequality in the US over a 55-year period, employing Theil’s entropy index to measure lifespan inequality and a Panel-Corrected Standard Errors (PCSE) model to assess associated socioeconomic and demographic factors. The analysis reveals a significant negative correlation between life expectancy and lifespan inequality across states. Educational attainment, health insurance coverage, and physician density show negative associations with lifespan inequality, whereas violent crime rates, smoking prevalence, and income inequality exhibit positive associations.
The second study investigates the impact of homicide on life expectancy and lifespan inequality at the state level in the US from 1968 to 2020, focusing on demographic, socioeconomic, and policy determinants. Utilizing data from the US Mortality Database and cause-eliminated life tables and Panel-Corrected Standard Errors (PCSE) models, the study reveals that Southern states experience the most substantial impacts on both life expectancy and lifespan inequality, while the Northeast exhibits comparatively lower effects. Males consistently face greater impacts than females. Key findings underscore systemic inequities: a higher percentage of Black populations and individuals aged 25–34 correlate with greater homicide-related reductions in life expectancy and increased lifespan inequality. Educational attainment, particularly the high school graduation rate, helps mitigate these effects. Corrections and judicial expenditures affect both life expectancy and lifespan inequality. In contrast, police and health spending are associated with decreases in lifespan inequality but no change in life expectancy, whereas welfare expenditures correlate with increased lifespan inequality but are correlated with life expectancy only for the total population.
The final study conducts a comparative analysis of the demographic impacts of three major pandemics: the 1918 influenza pandemic, the HIV/AIDS epidemic, and the COVID-19 pandemic on global life expectancy and lifespan inequality. The study finds that the 1918 influenza pandemic caused the most pronounced reductions in life expectancy, especially among young adults, thereby leading to substantial lifespan inequality. By contrast, HIV/AIDS had a gradual yet enduring impact, predominantly affecting young and middle-aged adults and exacerbating health disparities in regions with limited healthcare resources. The COVID-19 pandemic primarily affected older populations, producing smaller reductions in life expectancy but uniquely decreasing lifespan inequality due to the concentration of mortality among the elderly. Gender-specific effects varied: while the 1918 influenza and COVID-19 pandemics showed relatively uniform gender impacts, HIV/AIDS disproportionately affected women.
Collectively, the findings across these studies underscore the need to address the interconnected issues of life expectancy, lifespan inequality, and systemic disparities. Targeted gender-specific policies and public expenditures (e.g., increased judicial and healthcare funding) have the potential to reshape mortality patterns and mitigate disparities. Pandemic responses should be tailored to protect vulnerable age and demographic groups by ensuring equitable access to healthcare and vaccines.

text: Three studies on life expectancy and lifespan inequality While life expectancy is a key indicator in public health and demography, it may obscure unequal experiences of different population groups. By contrast, lifespan inequality captures variations in age at death, offering a broader view of health disparities. Focusing on lifespan inequality enables policymakers and researchers to identify vulnerable populations, design more equitable health and social policies, and evaluate progress toward reducing inequities. 
This thesis is comprised of three interrelated studies that examine life expectancy and lifespan inequality from different perspectives. The first study explores state-level variations in life expectancy and lifespan inequality in the US over a 55-year period, employing Theil’s entropy index to measure lifespan inequality and a Panel-Corrected Standard Errors (PCSE) model to assess associated socioeconomic and demographic factors. The analysis reveals a significant negative correlation between life expectancy and lifespan inequality across states. Educational attainment, health insurance coverage, and physician density show negative associations with lifespan inequality, whereas violent crime rates, smoking prevalence, and income inequality exhibit positive associations.
The second study investigates the impact of homicide on life expectancy and lifespan inequality at the state level in the US from 1968 to 2020, focusing on demographic, socioeconomic, and policy determinants. Utilizing data from the US Mortality Database and cause-eliminated life tables and Panel-Corrected Standard Errors (PCSE) models, the study reveals that Southern states experience the most substantial impacts on both life expectancy and lifespan inequality, while the Northeast exhibits comparatively lower effects. Males consistently face greater impacts than females. Key findings underscore systemic inequities: a higher percentage of Black populations and individuals aged 25–34 correlate with greater homicide-related reductions in life expectancy and increased lifespan inequality. Educational attainment, particularly the high school graduation rate, helps mitigate these effects. Corrections and judicial expenditures affect both life expectancy and lifespan inequality. In contrast, police and health spending are associated with decreases in lifespan inequality but no change in life expectancy, whereas welfare expenditures correlate with increased lifespan inequality but are correlated with life expectancy only for the total population.
The final study conducts a comparative analysis of the demographic impacts of three major pandemics: the 1918 influenza pandemic, the HIV/AIDS epidemic, and the COVID-19 pandemic on global life expectancy and lifespan inequality. The study finds that the 1918 influenza pandemic caused the most pronounced reductions in life expectancy, especially among young adults, thereby leading to substantial lifespan inequality. By contrast, HIV/AIDS had a gradual yet enduring impact, predominantly affecting young and middle-aged adults and exacerbating health disparities in regions with limited healthcare resources. The COVID-19 pandemic primarily affected older populations, producing smaller reductions in life expectancy but uniquely decreasing lifespan inequality due to the concentration of mortality among the elderly. Gender-specific effects varied: while the 1918 influenza and COVID-19 pandemics showed relatively uniform gender impacts, HIV/AIDS disproportionately affected women.
Collectively, the findings across these studies underscore the need to address the interconnected issues of life expectancy, lifespan inequality, and systemic disparities. Targeted gender-specific policies and public expenditures (e.g., increased judicial and healthcare funding) have the potential to reshape mortality patterns and mitigate disparities. Pandemic responses should be tailored to protect vulnerable age and demographic groups by ensuring equitable access to healthcare and vaccines.

year: 2025

title: Motives for luxury seafood consumption in first-tier cities in China

authors: Wang, Ou

subjects: Science & Technology

abstract: This study explored Chinese consumers’ choice motives, motive dimensions, segmentation, and species preferences on luxury seafood consumption. A web-based survey was administered to 967 luxury seafood eaters from three cities: Beijing, Shenzhen, and Shanghai. The data were analysed by descriptive analysis, principal component analysis (PCA), cluster analysis, and linear regression analysis. A two-dimensional construct was obtained for Chinese consumers’ choice motives for luxury seafood: food value and symbolic value. The most important specific motives attached to these two dimensions included umami, delicious, fresh, like to eat, show status, face consciousness, high quality life, and networking. Luxury seafood consumption by Chinese consumers was more significantly influenced by the symbolic value motivation dimension than the food value dimension. Two consumer segments were found: food value seeker (42.4%) and dual value seeker (57.6%). Lobster and salmon were the most common luxury seafood species consumed in China.

text: Motives for luxury seafood consumption in first-tier cities in China This study explored Chinese consumers’ choice motives, motive dimensions, segmentation, and species preferences on luxury seafood consumption. A web-based survey was administered to 967 luxury seafood eaters from three cities: Beijing, Shenzhen, and Shanghai. The data were analysed by descriptive analysis, principal component analysis (PCA), cluster analysis, and linear regression analysis. A two-dimensional construct was obtained for Chinese consumers’ choice motives for luxury seafood: food value and symbolic value. The most important specific motives attached to these two dimensions included umami, delicious, fresh, like to eat, show status, face consciousness, high quality life, and networking. Luxury seafood consumption by Chinese consumers was more significantly influenced by the symbolic value motivation dimension than the food value dimension. Two consumer segments were found: food value seeker (42.4%) and dual value seeker (57.6%). Lobster and salmon were the most common luxury seafood species consumed in China.

year: 2020

title: eDNA-based detection of New Zealand freshwater mussel (kākahi) populations using digital PCR

authors: Ferris, Kelsey

subjects: eDNA

abstract: Globally, freshwater mussels are one of the most endangered taxa due to pollution, nutrient loading, habitat fragmentation, and species introduction attributable to anthropogenic activities. New Zealand freshwater mussels (kākahi) are ecological engineers and integral species in freshwater ecosystems. However, kākahi populations are expected to decline 70% by 2024 in part due to their unique reproductive cycle involving an obligatory phoretic relationship with declining native fish. Kākahi distribution and abundance throughout New Zealand is poorly understood due to time-consuming surveying techniques of concealed and morphologically cryptic species. A rapid and reliable method is required for the detection and identification of these ‘Threatened’ kākahi populations for conservation and management. Therefore, this study aimed to i) validate an environmental DNA (eDNA) based detection method for New Zealand freshwater mussels using digital PCR (dPCR); ii) determine the most appropriate sampling season for kākahi eDNA; and iii) determine whether eDNA could be used to detect effects of fish barriers on kākahi distribution.
In vivo trials determined that filtration of field samples within 24 hours of collection minimised eDNA degradation and that prefiltration effectively removed inhibitory detritus and glochidia. The lowest concentration of eDNA which could accurately be detected to infer abundance (≥3.2 copies/µL) or presence (0.32-3.19 copies/µL) of kākahi eDNA was determined.  Duplicate field samples were collected from the Waingaro River and Kahuhuru Stream at sites downstream of fish barriers and upstream of low-flow or all-flow barriers in December, May, and August to investigate spatial and temporal variation in eDNA concentrations. As hypothesised, December was the most effective month to sample, yielding the highest eDNA concentrations due to reduced dilution and heightened water temperatures. Based on eDNA, kākahi species distribution did not appear correlated with fish barriers, but all-flow barriers likely impeded fish host movement to significantly reduce the total kākahi eDNA concentrations found upstream. 
eDNA detection can be used by regional councils to effectively infer presence/absence of kākahi populations and direct further conventional surveying efforts to the most impactful locations. This method allows rapid determination of distribution and densities at a national scale to aid conservation management of this taonga (treasured) species.

text: eDNA-based detection of New Zealand freshwater mussel (kākahi) populations using digital PCR Globally, freshwater mussels are one of the most endangered taxa due to pollution, nutrient loading, habitat fragmentation, and species introduction attributable to anthropogenic activities. New Zealand freshwater mussels (kākahi) are ecological engineers and integral species in freshwater ecosystems. However, kākahi populations are expected to decline 70% by 2024 in part due to their unique reproductive cycle involving an obligatory phoretic relationship with declining native fish. Kākahi distribution and abundance throughout New Zealand is poorly understood due to time-consuming surveying techniques of concealed and morphologically cryptic species. A rapid and reliable method is required for the detection and identification of these ‘Threatened’ kākahi populations for conservation and management. Therefore, this study aimed to i) validate an environmental DNA (eDNA) based detection method for New Zealand freshwater mussels using digital PCR (dPCR); ii) determine the most appropriate sampling season for kākahi eDNA; and iii) determine whether eDNA could be used to detect effects of fish barriers on kākahi distribution.
In vivo trials determined that filtration of field samples within 24 hours of collection minimised eDNA degradation and that prefiltration effectively removed inhibitory detritus and glochidia. The lowest concentration of eDNA which could accurately be detected to infer abundance (≥3.2 copies/µL) or presence (0.32-3.19 copies/µL) of kākahi eDNA was determined.  Duplicate field samples were collected from the Waingaro River and Kahuhuru Stream at sites downstream of fish barriers and upstream of low-flow or all-flow barriers in December, May, and August to investigate spatial and temporal variation in eDNA concentrations. As hypothesised, December was the most effective month to sample, yielding the highest eDNA concentrations due to reduced dilution and heightened water temperatures. Based on eDNA, kākahi species distribution did not appear correlated with fish barriers, but all-flow barriers likely impeded fish host movement to significantly reduce the total kākahi eDNA concentrations found upstream. 
eDNA detection can be used by regional councils to effectively infer presence/absence of kākahi populations and direct further conventional surveying efforts to the most impactful locations. This method allows rapid determination of distribution and densities at a national scale to aid conservation management of this taonga (treasured) species.

year: 2020