Age Structure Of Population Research Articles

A Hierarchical Bayesian Model for Estimating Age-Specific COVID-19 Infection Fatality Rates in Developing Countries.

The COVID-19 infection fatality rate (IFR) is the proportion of individuals infected with SARS-CoV-2 who subsequently die. As COVID-19 disproportionately affects older individuals, age-specific IFR estimates are imperative to facilitate comparisons of the impact of COVID-19 between locations and prioritize distribution of scarce resources. However, there lacks a coherent method to synthesize available data to create estimates of IFR and seroprevalence that vary continuously with age and adequately reflect uncertainties inherent in the underlying data. In this article, we introduce a novel Bayesian hierarchical model to estimate IFR as a continuous function of age that acknowledges heterogeneity in population age structure across locations and accounts for uncertainty in the estimates due to seroprevalence sampling variability and the imperfect serology test assays. Our approach simultaneously models test assay characteristics, serology, and death data, where the serology and death data are often available only for binned age groups. Information is shared across locations through hierarchical modeling to improve estimation of the parameters with limited data. Modeling data from 26 developing country locations during the first year of the COVID-19 pandemic, we found seroprevalence did not change dramatically with age, and the IFR at age 60 was above the high-income country estimate for most locations.

The Potential of Internal Migration to Shape Rural and Urban Populations Across Africa, Asia, and Latin America

AbstractSubnational divergence in the age and sex structures of populations can have far‐stretching consequences for development: from marriage markets to the potential for violence to economic growth. With urbanization and the demographic transition still underway, rural and urban populations continue to differ across low‐ and middle‐income countries. We examine the extent by which internal migration contributes to these differences, from 1970 to 2014 using estimates of migration between rural and urban sectors based on census data from 45 countries. We found that despite heavily delineated migration profiles by age and sex, internal migration does not alter sex and age structures of rural and urban populations. All the same, internal migration does increase urban growth in Asia and Latin America and the Caribbean. In contrast, in Africa, internal migration has little leverage with the urban transition. Across the continents, there is a potential for de‐urbanization, driven by a rural/urban gap in fertility. As such, the rural population may continue to constitute a significant proportion of national populations, necessitating critical investments to ensure they are not left behind.

Population age structure and conservation status of Ferula sinkiangensis (Apiaceae) in Xinjiang, China

Abstract Ferula sinkiangensis K.M. Shen is a threatened medicinal plant endemic to Xinjiang, China, with a small population size and a narrow distribution range. We assessed the status of this species with respect to its population age structure, the level of threat and extinction risk. Only one population remains, in Yining County, Xinjiang. We conducted field surveys of the population in 2022 and 2023, counting 2,033 and 1,515 individuals, respectively, in 144 sample quadrats. We assessed the age structure of the population by counting the number of basal leaves of each individual. The frequency distribution had an inverted J-shape, indicative of a relatively stable age structure. However, the number of mature individuals was small, raising concerns about the risk of genetic drift and inbreeding. This species is also threatened by habitat destruction and inappropriate collection practices. We recommend that F. sinkiangensis is categorized as Critically Endangered on the IUCN Red List on the basis of criteria B2ab(iii), C2a(i) and D.

Insights into trypanosomiasis transmission: Age, infection rates, and bloodmeal analysis of Glossina fuscipes fuscipes in N.W. Uganda.

Tsetse flies (Glossina) transmit species of Trypanosoma which cause human African trypanosomiasis (HAT) and animal African trypanosomiasis (AAT). Understanding the epidemiology of this disease and controlling the vector rationally requires analysis of the abundance, age structure, infection rates and feeding patterns of tsetse populations. We analysed a population of G. fuscipes fuscipes in the Koboko district of Uganda. Seasonal variation in the abundance of tsetse was assessed from the numbers of tsetse caught in pyramidal traps. The age structure of the population was assessed by dissecting female tsetse to estimate their ovarian categories. Classical and PCR-based methods were utilised to determine the presence of the three major pathogenic species of salivarian trypanosomes: T. vivax, T. congolense and T. brucei in a subset (n = 2369) of flies. Further, bloodmeal analysis was carried using PCR to amplify and sequence a portion of the vertebrate cytb gene. The abundance and age structure of tsetse populations were relatively stable and a slight seasonal four-fold variation in abundance appeared to be correlated with rainfall. Analyses of age structure suggests a low natural daily mortality of 1.75% (1.62-1.88). Infection rates estimated were significantly greater (1.9-9.3 times) using the PCR-based method compared to the classical dissection-based method. Positive rates for T. brucei sl, T. congolense and T. vivax were 1.6% (1.32-2.24), 2.4% (1.83-3.11and 2.0% (1.46-2.63), respectively by PCR. The majority of bloodmeals were identified as cattle (39%, 30.5-47.8) and human (37% of meals, 28.4-45.6). The seasonally stable abundance, low mortality rate and high proportion of bloodmeals from humans may explain, in part, why this district has historically been a focus of sleeping sickness. Additionally, the high rates of cattle feeding indicate insecticide treated cattle may prove to be a useful vector control strategy in the area.

Shifting Sands: Examining and Mapping the Population Structure of Greece Through the Last Three Censuses

This paper aims to facilitate a more nuanced understanding of regional disparities in the population age structure at a local scale by applying a recent method for visualizing these disparities. Utilizing data from the three most recent population censuses in Greece, this method applies advanced data visualization techniques to map age distributions, highlighting significant variations in aging patterns across municipalities, towns, and districts. Traditional demographic analysis often overlooks local heterogeneities, leading to broad policies that often fail to address the unique needs of specific regions. Detailed maps are created by integrating geographic data with census data (using R and GIS), enabling policymakers to pinpoint areas with specific demographic challenges and opportunities. This localized approach reveals critical insights, such as regions experiencing rapid population aging, areas with younger population profiles, and zones undergoing demographic transitions. The visualization tool significantly improves the formulation of targeted strategies, enhancing the effectiveness of policies related to healthcare, workforce planning, and social services distribution. Through case studies and comparative analysis, we demonstrate the practical applications and advantages of this method in shaping public policy and strategic planning. This paper contributes to the field of geodemography by introducing and demonstrating a visualization method that enhances the accuracy of demographic analysis, providing policy makers with useful information to better address local demographic challenges and tailor strategies to specific regional needs.

Health, an ageing labour force, and the economy: Does health moderate the relationship between population age-structure and economic growth?

Abstract Research often suggests that population ageing will be detrimental for the economy due to increased labour market exits and lost productivity, however the role of population health and disability at older ages is not well established. Identifying whether the health of older people affects economic outcomes is challenging due to methodological issues. Using country-level panel data, we estimate the relationship between the size of the older working age population (aged 55-69) and economic growth across 180 countries from 1990 to 2017. We run models using annual data and 5-year moving averages of real per capita GDP growth as dependent variables. This enables us to quantify the gains in real per capita GDP growth associated with a healthy older working-age population on a country-by-country basis. The initial models confirm an inverse-U or hump-shaped relationship between population age groups and economic growth. In the 5 year average GDP growth model, the coefficient for the inverse of YLDs among 55-69 year olds is positive and significant at p < 0.01. The interaction term is significant at p < 0.001 in the same model. Across all countries, a 5% improvement in YLDs is associated with at minimum 0.3% predicted additional annual real per capita GDP growth. While a larger share of the older working-age population at ages 55-69 has historically been associated with slower real per capita GDP growth, low levels of disability in this age group can reduce or even eliminate these adverse economic effects. We consistently find a significant positive interaction between disability and the share of the population at ages 55-69, suggesting that adverse economic effects are amenable to policy intervention.

Age structure of carp and catfish catch as a tool to assess ecological health of fished stocks from the Ganga River system with special reference to Mahseer Tor tor (Hamilton, 1822)

In the 20th centuary, the economically important carp species Labeo rohita, Tor tor, & Labeo calbasu and the catfishes Rita rita & Bagarius bagarius contributed substantially to the total fish catch from the Ganga River system in India. Samples were recorded between December 2003 and June 2004 from fish landing centers in the Ken, Paisuni, and Tons rivers for L. rohita, T. tor and L. calbasu. Rita rita and B. bagarius were sampled between September 2001 and September 2003 in the Ganga River system. The data were used to evaluate the growth and age structures of fish populations. Age classes varied 0+–5+ for L. rohita in the Ken & Paisuni rivers and 0+–8+ in the Tons River. For T. tor, the age classes varied 1+–6+ in the Ken & Paisuni rivers and 1+–8+ in the Tons. Age classes of L. calbasu varied 1+–6+ in the Ken River, 1+–5+ in the Paisuni River, and 1+–7+ in the Tons. In the Ganga River, age classes of R. rita & B. bagarius varied 0+–7+ and 0+–6+, respectively. The L. rohita, age pyramid showed a tendency for bell shape in Ken River, base tends to be broader through bell shape in Paisuni River, and bell-shaped age pyramid was slightly distorted in Tons River. In case of T. tor, tendency for bell shape in Ken River and bell-shaped age pyramid in Paisun River & Tons River were obtained. In case of L. calbasu, heavy bottom shaped age pyramid was recorded in Ken and Paisuni rivers, while base tends to be broader in the Tons River. Bell shaped age pyramid was recorded for B. bagarius in the Ganga River while heavy bottom shape for R. rita in the Ganga River. Overall, T. tor is facing heavy fishing pressure and also targeted fish species by fishermen from the Ganga River system.

Reconstruction of China’s population age and education structure from 2000 to 2020—based on the data from the 5th to 7th national population censuses in China

Reconstruction of China’s population age and education structure from 2000 to 2020—based on the data from the 5th to 7th national population censuses in China

Age, Growth, Sex Composition, and Diet of the Burbot, Lota lota, the Only Freshwater Species of the Family Lotidae in the Amur (Heilongjiang) River, Northeast China

Information about the population structure, including the age and sex composition, growth characteristics, and diet of fish, is essential for the conservation and sustainable exploitation of fish stock. The burbot, Lota lota, is the only freshwater species of the family Lotidae in the Amur (Heilongjiang) River catchment located in northeastern China. Information on the biological characteristics and data on the population structure of this fish from the Amur River are scarce. To study these factors in burbot, Lota lota, in the Amur River of China, 749 specimens from four sampling areas were taken and analyzed in October 2022, January 2023, and May 2023. The ages of the sampled fish ranged from 1+ to 7+ years. The female/male ratio was 1.04:1, and body length and mass varied from 175 to 595 mm and 73.5 to 1958.7 g, respectively. The length–weight regression parameter b value was estimated as 2.80. The parameters of the von Bertalanffy growth model were L∞ = 596, K = 0.221, and t0 = −0.771 for all sampled fish; L∞ = 625, K = 0.208, and t0 = −0.756 for females; and L∞ = 584, K = 0.219, and t0 = −0.980 for males. The analysis of the stomach contents showed fish to be the major source of nutrition across all areas and sampling periods. In January, the secondary prey of burbots in the Huma reach of the upper Amur River was aquatic insect larvae, while, in the Tongjiang and Fuyuan reaches of the middle Amur River, the secondary prey was shrimp. The mean stomach fullness index and rate of empty stomachs differed with the sampling area, with the greatest proportion of empty stomachs observed in the Luobei reach of the middle Amur River, and the lowest in the Tongjiang and Fuyuan reaches. The mean stomach fullness index showed the opposite trend. In the Huma reach, the contributions of fish to the diet and the mean stomach fullness index were significantly higher in May than in October and January. The study provides the first detailed information on the population age and sex structure, growth patterns, and feeding ecology of burbots from the Amur River, China. The results will aid in formulating management strategies and regulations for local populations of burbots in the Amur River, China.

Bioresources of lake Mostovoye and ways of their rational use

The ichthyofauna of most water bodies in the Altai Krai is represented by low-value and slow-growing fish. Fish productivity is largely determined by the degree of exploitation of the reservoir and the form of organization of the fishery. Rational fishery in natural reservoirs should ensure the exploitation of the ecosystem of the reservoir as a single whole. Mostovoe Lake is located in the Zavyalovsky and Baevsky districts of the Altai Krai, is one of the largest freshwater lakes in the Altai Territory, belonging to the floodplain of the Kulunda River. The water in the reservoir is of the sulfate-chloride class of the first type, fully meets all fish farming requirements. The collection of ichthyological material was carried out by the method of control catches. The species composition and spatial distribution of fish were studied by setting a set of fixed gill nets in the reservoirs. Information on the size and age structure of populations, catches of the main commercial fish and crayfish in Mostovoe Lake is provided. The magnitude of the fishing effort and the assessment of the state of aquatic bioresources (ichthyofauna) in the reservoir were carried out using one of the expert assessment options — the point systems method. The ichthyofauna of Mostovoe Lake includes six species that are subject to commercial fishing: common pike, roach, silver carp, river perch, common carp (carp), and common pike perch. Of the commercial invertebrates, crayfish is caught. The indicators of the commercial stock and the recommended catch of bioresources in the reservoir were calculated. Recommendations for regulating fisheries based on ichthyological monitoring are proposed. A certain effect for stabilizing the structure of the ichthyocenosis of the reservoir can be made by fishery melioration: the introduction of herbivorous fish — white amur (Ctenopharyngodon idella) and silver carp (Hypophthalmichthys molitrix) for a more complete use of the food base of the lake — phytoplankton and macrophytes. It is necessary to continue monitoring studies of the lake’s winter oxygen regime.

A Survey on Computational Methods in Drug Discovery for Neurodegenerative Diseases.

Currently, the age structure of the world population is changing due to declining birth rates and increasing life expectancy. As a result, physicians worldwide have to treat an increasing number of age-related diseases, of which neurological disorders represent a significant part. In this context, there is an urgent need to discover new therapeutic approaches to counteract the effects of neurodegeneration on human health, and computational science can be of pivotal importance for more effective neurodrug discovery. The knowledge of the molecular structure of the receptors and other biomolecules involved in neurological pathogenesis facilitates the design of new molecules as potential drugs to be used in the fight against diseases of high social relevance such as dementia, Alzheimer's disease (AD) and Parkinson's disease (PD), to cite only a few. However, the absence of comprehensive guidelines regarding the strengths and weaknesses of alternative approaches creates a fragmented and disconnected field, resulting in missed opportunities to enhance performance and achieve successful applications. This review aims to summarize some of the most innovative strategies based on computational methods used for neurodrug development. In particular, recent applications and the state-of-the-art of molecular docking and artificial intelligence for ligand- and target-based approaches in novel drug design were reviewed, highlighting the crucial role of in silico methods in the context of neurodrug discovery for neurodegenerative diseases.

Analysis Of the Impact of China's Population Age Structure on Residential Commercial Housing Prices

With the intensification of global aging, the impact of changes in population age structure on the real estate market is becoming increasingly significant. This article aims to explore the impact of changes in China's population age structure on the prices of residential commercial housing, to provide a scientific basis for regulating the real estate market. By analyzing data from 30 provinces and cities in China from 2013 to 2022, this article finds that as aging population intensifies and the number of children decreases, both the old-age dependency ratio and the child-age dependency ratio have a negative impact on housing prices. This means that the aging society and the economic pressure of childcare may weaken the demand for home purchases. Household Saving Rate and increase in total population positively drive house prices, while the relationship between per capita income and house prices is not significant. From a regional perspective, the aging population in the eastern region has a significant effect on suppressing housing prices, while the impact is gradually evident in the central region. The western region has a smaller impact and population growth suppresses housing price increases. The study emphasizes the impact of changes in the age structure of the Chinese population on the prices of residential properties and proposes policy recommendations such as improving old-age security and optimizing the housing supply structure to promote the steady development of the real estate market.

Resource stock, age structure, and seed prediction of ferula sinkiangensis K.M. Shen

Ferula sinkiangensis K.M. Shen (FS) is an endemic species in Xinjiang, China. It has extremely high economic and medicinal value but is on the brink of extinction. A comprehensive survey of the distribution area of FS was conducted to study its resource stock, age structure and yielding capacity of seeds. Results show that there is one existing distribution area of FS with an area of 322.84 hm2 and a total plant quantity of 907,100. The age structure of FS population is reasonable showing a growing type of population. After low-temperature treatment and indoor germination of the seeds of FS, the utilization efficiency of seeds was increased by 15.45 times and 1165.81 times respectively. The establishment of the original habitat protection zone has played a huge role in promoting the recovery of the population of FS and the indoor germination of seeds would greatly alleviate the problem of seeds shortage of FS. Bangladesh J. Bot. 53(3): 765-772, 2024 (September) Special

Marine reserves can buffer against environmental fluctuations for overexploited but not sustainably harvested fisheries.

Globally, decision-makers are seeking management levers that can mitigate the negative effects of climate change on ecosystems that have already been transformed from their natural state by the effects of fishing. An important question is whether marine reserves can provide buffering (i.e., population-level resilience) against climate disturbances to fished populations. Here, we examine one aspect of this question, by asking whether marine reserves can reduce the variability in either overall biomass or in fishery yield, in the face of environmental variability. This could happen because greater reproduction of longer-lived, larger fish inside reserves could supplement recruitment to the fished portion of the population. We addressed this question using age-structured population models, assuming a system where some proportion of the coastline is protected in marine reserves (0%-30%), and the remainder is fished (at a range of possible harvest rates). We modeled populations with sedentary adults and dispersal via a larval pool. Since recent extreme climate events (e.g., marine heatwaves) have reduced juvenile survival for some fish species, we assumed that environmental variability affected the survival of the first age class in our model. We viewed population variability as a question of buffering, measured as the proportion of time a simulated population spent below a target reference point, with the idea that marine reserves could prevent the population from reaching low levels in the face of fishing and environmental variability. We found that fisheries with more area in marine reserves always had less variability in biomass. However, adding marine reserves only reduced variability in fisheries yield when the fished part of the population was being harvested at a rate exceeding the maximum sustainable yield. This new result on reducing variability is in line with previous findings that the "spillover" effects of marine reserve benefits to fishery yields only accrue when the fishery outside reserve boundaries is being overharvested.

Coevolution of non-pharmaceutical interventions and infectious disease spreading in age-structured populations

In the face of emerging major infectious diseases, non-pharmaceutical interventions (NPIs) such as mask-wearing are the primary means of disease control in the early stages due to the lack of effective pharmaceutical interventions. Yet the current understanding of the dynamic feedback loop between NPIs and infectious disease spreading remains limited. In this study, we proposed an asymmetrically coupled dynamic model of the coevolution of mask-wearing behaviour and infectious disease spreading in an age-structured population to describe the bidirectional relationship between NPIs such as mask-wearing and infectious disease spreading. A theoretical analysis framework was developed by extending the microscopic Markov chain method. To reflect the spreading process more realistically, we conducted numerical simulations from a mesoscopic perspective through an age-contact data-driven approach. Critical transition, multi-wave epidemics, multi-transitions, and mixed-phase transitions resulting from the coevolution of mask and disease are observed. The results highlight the critical role of NPIs in controlling disease spreading. The mask-wearing can effectively reduce the daily peak infection density and prevent large-scale outbreaks within a short period. However, it will also prolong the duration of the epidemic and cause the disease to exist in the population for a long time. There is a trade-off between the two. For certain diseases with specific spreading capabilities, pharmaceutical interventions such as vaccination, which can directly reduce the disease’s infectiousness, may result in more people being infected if NPIs are not implemented as early as possible. In addition, results from Anhui indicate that people aged 42 years are at high risk of being infected because of their large population base, which suggests that priority should be given to the prevention and control of this group.

A convergence analysis for the approximation to the solution of an age-structured population model with infinite lifespan

Considering the numerical approximation of the density distribution for an age-structured population model with unbounded lifespan on a compact interval [0,T], we prove second order of convergence for a discretization that adaptively selects its truncated age-interval according to the exponential rate of decay with age of the solution of the model. It appears that the adaptive capacity of the length in the truncated age-interval of the discretization to the infinity lifespan is a very convenient approach for a long-time integration of the model to establish the asymptotic behavior of its dynamics numerically. The analysis of convergence uses an appropriate weighted maximum norm with exponential weights to cope with the unbounded age lifespan. We report experiments to exhibit numerically the theoretical results and the asymptotic behaviour of the dynamics for an age-structured squirrel population model introduced by Sulsky.

Reexamining exposure from truck emissions considering daily movement of individuals

With the growing demand for urban freight transportation, trucks emit a large amount of pollutants such as particulate matters and nitrogen oxides, increasingly affecting public health. This study establishes a modelized air dispersion structure to simulate pollutant concentration distribution. By integrating multiple data sources including mobile phone signals and satellite images, we reconstruct the daily trajectories of individuals and further incorporate simulated pollution concentrations in calculating dynamic and static exposure of individuals to truck emissions. Econometric models considering spatial dependence are developed to evaluate the influencing factors and elucidate the mechanisms of pollutant exposure. Results show factors including freight demand, road network, residential and employment locations, personal commuting distance, and population age structure matter in assessing truck emission exposure. As a result, a mixture of vehicular emission standards, urban traffic control, land planning, and industrial policies is proposed to reduce truck pollutant exposure and safeguard public health.

Quantifying age-specific household contacts in Aotearoa New Zealand for infectious disease modelling.

Accounting for population age structure and age-specific contact patterns is crucial for accurate modelling of human infectious disease dynamics and impact. A common approach is to use contact matrices, which estimate the number of contacts between individuals of different ages. These contact matrices are frequently based on data collected from populations with very different demographic and socio-economic characteristics from the population of interest. Here we use a comprehensive household composition dataset based on Aotearoa New Zealand census and administrative data to construct a household contact matrix and a synthetic population that can be used for modelling. We investigate the behaviour of a compartment-based and an agent-based epidemic model parametrized using these data, compared with a commonly used contact matrix that was constructed by projecting international data onto New Zealand's population. We find that using the New Zealand household data, either in a compartment-based model or in an agent-based model, leads to lower attack rates in older age groups compared with using the projected contact matrix. This difference becomes larger when household transmission is more dominant relative to non-household transmission. We provide electronic versions of the synthetic population and household contact matrix for other researchers to use in infectious disease models.

Population age structure dependency of the excess mortality P-score

BackgroundSince the outbreak of the COVID-19 pandemic, the excess mortality P-score has gained prominence as a measure of pandemic burden. The P-score indicates the percentage by which observed deaths deviate from expected deaths. As the P-score is regularly used to compare excess mortality between countries, questions arise regarding the age dependency of the measure. In this paper we present formal and empirical results on the population structure bias of the P-score with a special focus on cross-country comparisons during the COVID-19 pandemic in Europe.MethodsP-scores were calculated for European countries for 2021, 2022, and 2023 using data from the 2024 revision of the United Nations’ World Population Prospects and the HMDs Short Term Mortality Fluctuations data series. The expected deaths for 2021, 2022, and 2023 were estimated using a Lee–Carter forecast model assuming pre-pandemic conditions. P-score differences between countries were decomposed using a Kitagawa-type decomposition into excess-mortality and structural components. To investigate the sensitivity of P-score cross-country rankings to differences in population structure we calculated the rank-correlation between age-standardized and classical P-scores.ResultsThe P-score is an average of age-specific percent excess deaths weighted by the age-distribution of expected deaths. It can be shown that the effect of differences in the distribution of deaths only plays a marginal role in a European comparison. In most cases, the excess mortality effect is the dominant effect. P-score rankings among European countries during the COVID-19 pandemic are similar under both age-standardized and classical P-scores.ConclusionsAlthough the P-score formally depends on the age-distribution of expected deaths, this structural component only plays a minor role in a European comparison, as the distribution of deaths across the continent is similar. Thus, the P-score is suitable as a measure of excess mortality in a European comparison, as it mainly reflects the differences in excess mortality. However, this finding should not be extrapolated to global comparisons, where countries could have very different death distributions. In situations were P-score comparisons are biased age-standardization can be applied as a solution.

Elderly care in an aging population: The impact of parental care needs on adult children

Abstract One of the challenges of population aging is the rising demand of elder care. Adult children fill a substantial portion of this care need. To understand its implication on their labor market choices and welfare outcomes, we build a simple static model where households can spend time and money producing care. We calibrate the model using data from the American Community Survey, the Health and Retirement Study, and National Health and Aging Trends Study/National Study of Caregiving to match moments in the labor market and caregiving patterns. With the calibrated model, we consider a few government programs under a projected aging population structure. Our results show that care subsidy and Medicaid expansion both cause a shift from informal care to formal care, relieving adult children from care burdens and thus improving their welfare. Caregiver allowance appears to have little effects on caregiving behaviors, which leads to minimal welfare improvement.