Effects Of Age Structure Research Articles

The importance of non-pharmaceutical interventions during the COVID-19 vaccine rollout.

The promise of efficacious vaccines against SARS-CoV-2 is fulfilled and vaccination campaigns have started worldwide. However, the fight against the pandemic is far from over. Here, we propose an age-structured compartmental model to study the interplay of disease transmission, vaccines rollout, and behavioural dynamics. We investigate, via in-silico simulations, individual and societal behavioural changes, possibly induced by the start of the vaccination campaigns, and manifested as a relaxation in the adoption of non-pharmaceutical interventions. We explore different vaccination rollout speeds, prioritization strategies, vaccine efficacy, as well as multiple behavioural responses. We apply our model to six countries worldwide (Egypt, Peru, Serbia, Ukraine, Canada, and Italy), selected to sample diverse socio-demographic and socio-economic contexts. To isolate the effects of age-structures and contacts patterns from the particular pandemic history of each location, we first study the model considering the same hypothetical initial epidemic scenario in all countries. We then calibrate the model using real epidemiological and mobility data for the different countries. Our findings suggest that early relaxation of safe behaviours can jeopardize the benefits brought by the vaccine in the short term: a fast vaccine distribution and policies aimed at keeping high compliance of individual safe behaviours are key to mitigate disease resurgence.

Effects of leaf age and canopy structure on gross ecosystem production in a subtropical evergreen Chinese fir forest

Despite the advances in technologies to derive the maximum rate of Rubisco carboxylation (Vcmax) seasonality at large-scale, factors controlling the temporal dynamics of Vcmax is largely unknown without extensive field measurements at stand scale. In addition, state-of-the-art process-based terrestrial ecosystem models had not accounted the complex canopy structure for estimating radiation interception by vegetation. Both of which could lead to uncertainties in gross ecosystem production (GEP) estimations. Here, we examined the respective and combined effects of leaf age and canopy structure on GEP by integrating the Farquhar photosynthesis model with a two-leaf (sunlit and shaded) canopy radiation interception model based on the Geometric Optical and Radiative Transfer (GORT) theory. We observed that the Vcmax of new leaves was approximately 34.4% higher than that of mature leaves. Considering the seasonal dynamics of Vcmax caused by new leaf expansion, the average bias between the modeled GEP and that derived from the eddy covariance (EC) in the growing season at 8-day temporal scale was reduced from -8% to -1%, with slightly higher correlation (from 0.9 to 0.92) and reduction in root mean squared error (from 6.0 to 3.9 g C m−2 8d−1). Most importantly, the total effect of new leaf expansion and canopy gaps during the growing season was +322 g C m−2 yr−1 and -114 g C m−2 yr−1, which was approximately 22.5% and 8.1% of the total GEP, respectively. Thus, it is important to consider both leaf age and canopy structure when developing a robust terrestrial ecosystem model. We highlighted that Vcmax seasonality and realistic canopy radiation interception simulation are critical for accurate estimation of canopy GEP for evergreen forests.

Demographic and epidemiological decomposition analysis of global changes in suicide rates and numbers over the period 1990–2019

BackgroundSuicide presents an ongoing public health challenge internationally. Nearly 800 000 people around the world lose their life to suicide every year, and many more attempt suicide.MethodsA decomposition analysis was...

Nexus of regional integration, socioeconomic determinants and sustainable development in belt and road initiative countries.

This study evaluates the nexus of regional integration, socioeconomic determinants and sustainable development (SD) by investigating the effect of health, humans and age structure on sustainable development, with the regional integration (RI) as the moderating variable. Socioeconomic determinants have an important role in sustainable development, while regional integration has fueled up the development process. The sample is based on 64 Belt and Road (BRI) countries from 2003–2018. Pair-wise correlation results indicate that human development, health expenditure and age structure showed a positive relationship with sustainable development. Two-step System-GMM direct effect outcomes are mixed and reveal that human development, health expenditure per capita, age structure, governance index and population size have a positive impact on sustainable development. On the other hand, e-government, government size, and globalization showed negative effects on SD. Apart from that, the moderating channel of regional integration (RI), interaction term with human development and health expenditure, showed a significant and positive impact on sustainable development. However, age structure interaction with regional integration showed a negative impact on SD. Other socio-economic factors, i.e., governance index and population contribute positively towards SD. It can be concluded that the dynamic nature of sustainable development is positive and the net present value is increasing. Therefore, BRI countries are on the sustainable path from 2003–2018, as suggested by economic and social welfare theory. The integration of BRI can be labeled as an entrance to successful sustainable development. However, weak e-government systems, globalization and government resources need to be utilized amicably in Belt and Road countries. Driscoll-Kraay standard-errors regression confirmed and validated the two-step System-GMM results. The findings of the current research have important policy implications for balanced and sustainable growth.

Pengaruh Corporate Governance, Firm Age, Dan Ownership Structure Terhadap Earning Management

The purpose of this study was to determine the effect of corporate governance, firm age, and ownership structure on earnings management. The population used is a company engaged in manufacturing which is listed on the Indonesia Stock Exchange (IDX) website, with a research period from 2016-2018. This research uses purposive sampling method with predetermined criteria. Earning management is calculated using the discretionary accruals method. The results of this study stated that corporate governance with an independent commissioners proxy had no significant negative effect on earnings management, firm age had a significant positive effect on earnings management, and ownership structure with a proxy for public ownership had a significant negative effect on earnings management.

Polychlorinated Naphthalenes across the Great Lakes: Lake Trout and Walleye Concentrations, Trends, and TEQ Assessment-2004-2018.

Polychlorinated naphthalenes (PCNs) were measured in lake trout and walleye over the period 2004-2018, utilizing isotope dilution techniques with high-resolution gas chromatography/high-resolution mass spectrometry to assess concentrations and toxic equivalence (TEQ). An age-trend model was applied to mitigate the effect of a changing lake trout age structure. Most Great Lakes Fish Monitoring and Surveillance Program sampling sites demonstrated significant half-life and percent decreases for lake trout total PCNs and total TEQ over the 2004-2018 period, the exceptions being Lake Erie lake trout and walleye which illustrated increasing concentrations. Great Lakes total PCN concentrations ranged between 5701 and 100 pg/g ww, whereas total PCN TEQ concentrations ranged between 8.89 and 0.13 pg-TEQ/g ww. Based on the average number of chlorines per naphthalene, we determined that the overall lake trout and walleye PCN congener distribution has significantly shifted to a lower-chlorinated composition in the Great Lakes (5.33 to 4.48 Cl/CN) and has resulted in a substantial 59.1% reduction of the overall total PCN TEQ burden. A prominent PCN concentration trend breakpoint was observed in Lake Ontario lake trout over the 2012-2016 period likely associated with hazardous waste cleanups, channel dredging, and spoils disposal in the Detroit River and western-basin of Lake Erie.

Effects of latency and age structure on the dynamics and containment of COVID-19

In this paper we develop an SEIR-type model of COVID-19, with account for two particular aspects: non-exponential distribution of incubation and recovery periods, as well as age structure of the population. For the mean-field model, which does not distinguish between different age groups, we demonstrate that including a more realistic Gamma distribution of incubation and recovery periods may not have an effect on the total number of deaths and the overall size of an epidemic, but it has a major effect in terms of increasing the peak numbers of infected and critical care cases, as well as on changing the timescales of an epidemic, both in terms of time to reach the peak, and the overall duration of an outbreak. In order to obtain more accurate estimates of disease progression and investigate different strategies for introducing and lifting the lockdown, we have also considered an age-structured version of the model, which has allowed us to include more accurate data on age-specific rates of hospitalisation and COVID-19 related mortality. Applying this model to three comparable neighbouring regions in the UK has delivered some fascinating insights regarding the effect of lockdown in regions with different population structure. We have discovered that for a fixed lockdown duration, the timing of its start is very important in the sense that the second epidemic wave after lifting the lockdown can be significantly smaller or larger depending on the specific population structure. Also, the later the fixed-duration lockdown is introduced, the smaller is the resulting final number of deaths at the end of the outbreak. When the lockdown is introduced simultaneously for all regions, increasing lockdown duration postpones and slightly reduces the epidemic peak, though without noticeable differences in peak magnitude between different lockdown durations.

Genetic polymorphism under cyclical selection in long-lived species: The complex effect of age structure and maternal selection

Maternal selection and overlapping generations can facilitate the stable coexistence of alleles under temporally fluctuating environment. Using mathematical models, we considered the complex effect of both factors on the maintenance of genetic polymorphism in cyclically changing environments. We concentrated on asymmetric cyclic selection, which allows describing fluctuations of environments by analogy of food resources cycles with rare peaks and prolonged decline of prey abundance.The complex effect of maternal selection and overlapping generations turned out to work as follows: although overlapping generations always tend to dilate the polymorphism region, odd and even external cycles produce different types of polymorphism regions. Maternal selection under external odd cycles extends the coexistence region comparing with classic selection. Even cycles produce a part of parameter region, where the picture changes radically, and classic selection becomes more effective in maintaining polymorphism.Our models have clear biological interpretation, because we tried to model a situation demonstrated by natural populations of arctic foxes. The litter size being a major life history trait is a sex-limited female trait. It is influenced by maternal selection with cyclical fluctuations because of oscillations in food abundance. Arctic fox is a long-lived species having an age structure. The obtained results showed that compared with the simple Mendelian inheritance in the classic model, this trait inheritance allows polymorphism to be maintained in a wider range of the parameter that characterizes the advantage of survival in a small litter. Besides, adding overlapping generations to the model further broadens the parameter space for the protected polymorphism. Thus, this study shows that maternal selection and overlapping generations increases the chances of maintaining polymorphism in populations of arctic foxes.

The Effects of Age Structure on Economic Growth: An Application of Probabilistic Forecasting in India

During recent years there has been an increasing awareness of the explanatory power of demographic variables in economic growth regressions. We estimate a new model of the effects of age structure change on economic growth. We use the new model and recent probabilistic demographic projections for India to derive the uncertainty of predicted economic growth rates caused by the uncertainty in demographic developments.

The effect of policy planning, population and age structure on carbon emission under different city scale

In recent years, air pollution has become more and more serious in the world. The transportation system in cities made a large contribution to carbon emission. Therefore, the problem of urban traffic pollution needed to be solved urgently. The city scale, population, the age structure of population and policy planning would influence the energy consumption and carbon emission of transportation systems. This article compared three different transportation systems: private motor vehicles, buses and subway in three cities. Beijing, Nanjing and Shijiazhuang were selected as the main cities which represented the different city scale. By reading the article about carbon emission from the transportation system and analyzing the research methods used before, this article analyzed the carbon emission from transportation in Beijing, Nanjing and Shijiazhuang. The article mainly included the following parts. First of all, ‘engineering technical model’ was used in this article. Using the ‘engineering technical model’ based on the data, which includes amounts of transportation tools, total miles, energy consumption and carbon emission factors, the carbon emission would be taken. Besides that, this article also predicted the carbon emission in 2035 based on ’The Fourteenth Five-Year Plan for the National Economic and Social Development of the People Republic of China and the Outline of the Long-range Goals to 2035’ to detect the effect of policy on carbon emission. At last, the cities with advanced transportation systems would have less carbon emission, but the super cities like Beijing still had the largest carbon emission. The age structure of the population also influenced carbon emission. Government policy was also the main influence factor for carbon emission. Under the government policy, the carbon emission of the transportation system decreased sharply.

Multiple Factors Influence Seasonal and Interannual Litterfall Production in a Tropical Dry Forest in Mexico

Litterfall production plays a fundamental role in the dynamics and function of tropical forest ecosystems, as it supplies 70–80% of nutrients entering the soil. This process varies annually and seasonally, depending on multiple environmental factors. However, few studies spanning several years have addressed the combined effect of climate variables, successional age, topography, and vegetation structure in tropical dry forests. In this study, we evaluated monthly, seasonal, and annual litterfall production over a five-year period in semideciduous dry forests of different successional ages growing on contrasting topographic conditions (sloping or flat terrain) in Yucatan, Mexico. Its relationship with climate and vegetation structural variables were also analyzed using multiple linear regression and generalized linear models. Litterfall was measured monthly in 12 litterfall traps of 0.5 m2 in three sampling clusters (sets of four 400 m2 sampling plots) established in forests of five successional age classes, 3–5, 10–17, 18–25, 60–79, and >80 years (in the latter two classes either on slopping or on flat terrain), for a total of 15 sampling clusters and 180 litterfall traps. Litterfall production varied between years (negatively correlated with precipitation), seasons (positively correlated with wind speed and maximum temperature), and months (negatively correlated with relative humidity) and was higher in flat than in sloping sites. Litterfall production also increased with successional age until 18–25 years after abandonment, when it attained values similar to those of mature forests. It was positively correlated with the aboveground biomass of deciduous species but negatively correlated with the basal area of evergreen species. Our results show a rapid recovery of litterfall production with successional age of these forests, which may increase with climate changes such as less precipitation, higher temperatures, and higher incidence of hurricanes.

Population Age Structure and Greenhouse Gas Emissions from Road Transportation: A Panel Cointegration Analysis of 21 OECD Countries.

Using panel data from 21 Organization for Economic Cooperation and Development (OECD) countries collected between 2000 and 2016, this study analyzes the effect of age structure on greenhouse gas (GHG) emissions from road transportation. Previous studies have failed to reflect the driver’s behavior patterns, especially by age group. We apply the Fully-Modified Ordinary Least Squares (FMOLS) method, including the age structure effect by reorganizing 17 age groups into a polynomial structure. The age structure exhibits an asymmetric inverted U-shaped effect on GHG emissions. Initially, people emit more GHGs as they age, and reach peak emissions in their late 20s, after which emissions fall until around the age of 70, when GHG emissions remain constant because of minimum mobility demand. Factors, such as higher income, increased vehicle ownership, and raised transport volumes increase emission rates. On the other hand, fuel transition and increased fuel price, population density, urbanization rate, and fuel economy reduce GHG emissions. Furthermore, we perform a projection of GHG emissions until 2050, and conclude that the effect of age structure is limited because of the minimum mobility demand of the elderly. We conclude that various policy measures, such as increased fuel economy and urbanization, must be considered in order to achieve sustainable transport

Concerning demographic limitations on the population growth rate of West Australian (Breeding Stock D) humpback whales

The upper bound of 0.126 on the maximum demographically possible annual growth rate for humpback whales that has standardly been imposedon recent applications of age-aggregated assessment models for this species in the IWC Scientific Committee, is based on an analysis that assumessteady age structure. It is conceivable that transient age-structure effects could admit greater population growth rates for short periods than suggestedby such a bound. This possibility is addressed by developing an age-structured population model in which possible density dependent changes inpregnancy rate, age at first parturition and natural mortality are modelled explicitly, and allowance is made for the possibility of natural mortalityincreasing at older ages. The model is applied to the case of the west Australian humpback whale population (Breeding Stock D), for which breedingground surveys over the 1982–1994 period provide a point estimate of 0.10 for the annual population growth rate. Results based upon the breedingpopulation survey estimate of abundance of 10,032 in 1999 suggest that 0.12 is the maximum demographically feasible annual rate of increase forthis stock over 1982–1994 if it is a closed population. This result is based on essentially the same parameter choices as led to the earlier r = 0.126bound, i.e. that in the limit of low population size the age at first parturition approaches five years from above, the annual pregnancy rate 0.5 frombelow, and the annual natural mortality rate 0.01 from above. Transient effects do not appear able to reconcile the observed rate of increase withless extreme values of demographic parameters than led to the previously imposed upper bound of 0.126 on the maximum possible annual growthrate. Although use of extreme values reported for demographic parameters for Northern Hemisphere humpback whale populations, rather than thoseconsidered here, would reduce this suggested maximum rate of 0.12, the conclusion that transient effects have a very limited impact on observedpopulation growth rates would be unlikely to change.

Use of Counterfactual Population Projections for Assessing the Demographic Determinants of Population Ageing

Counterfactual population projections have been used to estimate the contributions of fertility and mortality to population ageing, a method recently designated as the gold standard for this purpose. We analyse projections with base years between 1850 and 1950 for 11 European countries with long-run demographic data series to estimate the robustness of this approach. We link this approach with stable population theory to derive quantitative indicators of the role of fertility and mortality; consider ways of incorporating net migration; and examine the effect of using alternative indicators of population ageing. A number of substantive and technical weaknesses in the counterfactual projection approach are identified: (1) the conclusions are very sensitive to the choice of base year. Specifically, the level of base year fertility has a major influence on whether fertility or mortality is considered the main driver of population ageing. (2) The method is not transitive: results for two adjacent intervals are unrelated to results for the combined period. Therefore, overall results cannot be usefully allocated between different sub-intervals. (3) Different ageing indices tend to produce similar qualitative conclusions, but quantitative results may differ markedly. (4) Comparisons of alternative models should be with a fixed fertility and mortality projection model rather than with the baseline values as usually done. (5) The standard counterfactual projections approach concatenates the effects of initial age structure and subsequent fertility and mortality rates: methods to separate these components are derived.

The effect of education on the demographic dividend: an analysis of the Brazilian case

The demographic dividend has aroused interest among demographers and economists because it is seen as a window of oportunity for the economic development of countries that have experienced a demographic transition. There are reasons to question the sole virtuosity of the pure demographic dividend in economic growth. Crespo-Cuaresma et al. (2014) found that educational expansion has an important role in economic gains during the demographic dividend. To verify these results for the Brazilian case, we performed a decomposition exercise of economic support ratio (ESR), an alternative to demographic dependency ratio, to analyze the first demographic dividend. A simulation, applied for the period from 1970 to 2100 considering three scenarios of educational expansion, shows that educational expansion was and will be responsible for a big share of the economic gains of the Brazilian demographic dividend period, outperforming the change in age structure effect. In addition, an increase in a work-age population with post-secondary education appears to potentialize these results.

Causal effects of population dynamics and environmental changes on spatial variability of marine fishes

Populations with homogeneous distributions have better bet-hedging capacity than more heterogeneously distributed populations. Both population dynamics and environmental factors may influence the spatial variability of a population, but clear empirical evidence of such causal linkages is sparse. Using 25-year fish survey data from the North Sea, we quantify causal effects of age structure, abundance, and environment on nine fish species. We use empirical dynamic modeling—an approach based on state-space reconstruction rather than correlation—to demonstrate causal effects of those factors on population spatial variability. The causal effects are detected in most study species, though direction and strength vary. Specifically, truncated age structure elevates population spatial variability. Warming and spatially heterogeneous temperatures may enhance population spatial variability, whereas abundance and large-scale environmental effects are inconclusive. Fishing may affect population spatial variability directly or indirectly by altering age structure or abundance. We infer potential harmful effects of fishing and environmental changes on fish population stability, highlighting the importance of considering spatial dynamics in fisheries management.

Relations Among Low-Income Preschool Children’s Self-Regulation, Marginal Food Security, and Parent Stress

ABSTRACT Research Findings: Marginal food security is less studied relative to food insecurity but may also have adverse effects on family outcomes. The present study examined whether parental stress mediated the relationship between marginal food security (MFS) and preschool-aged children’s observed self-regulation at three early education centers located in two urban cities in a Midwestern state. Primary caregivers (81.3% mothers) completed an adapted version of the Parenting Stress Index-Short Form and a two-question screener from the USDA Annual Food Security Survey. Children’s aged 37-70 months, M= 54, SD = 6.46; 57% boys) self-regulation skills were directly assessed. Approximately one-third (39.75%) of the present sample were considered MFS, as they reported being “worried that food would not last” in the past 12 months. MFS families had significantly higher levels of parental stress than food secure families. Additionally, MFS indirectly affects children’s observed self-regulation skills through parental stress, even after controlling for the effect of child age, sex, and family structure. Practice or Policy: Implications of this finding for early intervention and food support programs are discussed.

The impact of age structure on carbon emission in the Middle East: the panel autoregressive distributed lag approach.

Rapid evolution in the population age structure of the Middle East countries has major economic, social, and environmental outcomes. Therefore, to fill the gap in the previous literatures, in this study, the effect of age structure on environmental degradation was investigated in the Middle East region. To achieve this goal, a panel data of 10 Middle East countries were examined over the period of 1990 to 2014. Moreover, the carbon dioxide emission per capita was used as an environmental pollution index in this study. According to the stationary property of the variables, small sample size data, and the assumptions of the model, the panel autoregressive distributed lag method of mean group, pooled mean group, and dynamic fixed effect estimators were investigated in this study. The empirical results implied that the pooled mean group model emerged as the most efficient among the three estimators. Also, results revealed that the age structure have a significant relationship with environmental pollution. Children and working age population have a positive elasticity, whereas elderly people have negative elasticity. Furthermore, the results showed that the working age population has the greatest explanatory power on the carbon emissions. Also, the relationship between per capita energy consumption and gross domestic product per capita with air pollution was positive. Overall, the empirical results showed that any attempt to decrease carbon dioxide emissions in the Middle East region should consider the population age structure.

年龄结构、接触模式和接种对手足口病传播机制的影响

In order to further reveal the transmission mechanism and optimize the immune strategy of the hand-foot-mouth disease (HFMD), a new HFMD transmission model was proposed under the effects of age structure, contact patterns and vaccination. The next generation matrix was used to calculate the basic reproduction number, and the theory of stability and dynamics was used to prove the existence and global stability of the disease-free and endemic equilibria. Finally numerical simulation was conducted to explore the effects of model parameters. It is found that age structure, contact matrices and vaccination have significant influence on the transmission, and the heterogeneity of age structure may worsen the infection, but quarantining patients and improving vaccination coverage vaccination rates can effectively help to control the disease. The results provide a scientific reference for the prevention and control of HFMD transmission.

Demographic aspects of the COVID-19 pandemic in Italy, Spain, Germany, and South Korea

The COVID-19 Pandemic has become an object of many studies and research papers. Although knowledge of the demographic features of the illness could be important for targeting the prevention, or treatment and evaluation, of the situation, demographic research was rather limited in the initial phases of the pandemic. This paper aims to present the basic demographic aspects of the illness (age-specific and crude rates) and to estimate the effects of age-specific rates and age structures on the overall, generally used measures. For this analysis, Italy, Spain, Germany, and South Korea were selected. The most important differences among these countries were traced based on the age-specific measures and age structures. The demographic method of decomposition was used for the most crucial part of the analysis. It was proven that the level of incidence (particularly at higher ages) is noticeably significant regarding the observed differences. The effects of population age structure and the level of fatality are somewhat weaker.