Predation is one of the basic mechanisms of population growth control. Using a mathematical model, we explore the impact of predation in a prey population structured into two age classes, juveniles and adults, assuming a generalist predator. The specific predation pressure is represented for each of the two age classes by either no predation or Holling type II or Holling type III functional responses in various combinations. We distinguish two scenarios. In the first one, we seek for potential Allee effects or multiple stable states in the prey population, and explore the conditions at which the predation is more effective on juveniles than adults and vice versa. The most interesting finding here is the occurrence of bistability, or a predator-pit-like behaviour, when predators consume only juvenile prey, via a Holling type II functional response, an observation not described previously. In case only adults or both age classes are killed by predators exhibiting a type II functional response, the Allee effect occurs frequently. Multiple positive stable states are commonly observed if one of the age classes is exploited via a type III functional response. In the second scenario, we assume that the prey feeds on a resource and that the resource together with the prey undergoes outbreak dynamics, and we examine possibilities of control of such outbreaks using age-specific predation. Predation was proven to be able to suppress the prey population successfully. In some cases, an oscillation-free resource-prey-predator coexistence was detected.

The relationship between population changes and economic growth has been debated since Malthus. Initially focusing on population growth, the notion of demographic dividend has shifted the attention to changes in age structures with an assumed window of opportunity that opens when falling birth rates lead to a relatively higher proportion of the working-age population. This has become the dominant paradigm in the field of population and development, and an advocacy tool for highlighting the benefits of family planning and fertility decline. While this view acknowledges that the dividend can only be realized if associated with investments in human capital, its causal trigger is still seen in exogenous fertility decline. In contrast, unified growth theory has established human capital as a trigger of both demographic transition and economic growth. We assess the relative importance of changing age structure and increasing human capital for economic growth for a panel of 165 countries during the time period of 1980-2015. The results show a clear dominance of improving education over age structure and give evidence that the demographic dividend is driven by human capital. Declining youth dependency ratios even show negative impacts on income growth when combined with low education. Based on a multidimensional understanding of demography that considers education in addition to age, and with a view to the additional effects of education on health and general resilience, we conclude that the true demographic dividend is a human capital dividend. Global population policies should thus focus on strengthening the human resource base for sustainable development.

The relationship between population changes and economic growth has been debated since Malthus. Initially focusing on population growth, the notion of demographic dividend has shifted the attention to changes in age structures with an assumed window of opportunity that opens when falling birth rates lead to a relatively higher proportion of the working-age population. This has become the dominant paradigm in the field of population and development, and an advocacy tool for highlighting the benefits of family planning and fertility decline. While this view acknowledges that the dividend can only be realized if associated with investments in human capital, its causal trigger is still seen in exogenous fertility decline. In contrast, unified growth theory has established human capital as a trigger of both demographic transition and economic growth. We assess the relative importance of changing age structure and increasing human capital for economic growth for a panel of 165 countries during the time period of 1980-2015. The results show a clear dominance of improving education over age structure and give evidence that the demographic dividend is driven by human capital. Declining youth dependency ratios even show negative impacts on income growth when combined with low education. Based on a multidimensional understanding of demography that considers education in addition to age, and with a view to the additional effects of education on health and general resilience, we conclude that the true demographic dividend is a human capital dividend. Global population policies should thus focus on strengthening the human resource base for sustainable development.

The population is one of the most important elements of any territory. As it changes, not one decennary interests a different profile of researchers. Work of the master on a theme "Changes of age structure population of Lithuania for 1989-2005" has chosen because for this period there were obvious changes. The structure age the population is important for employment of the population, also for the analysis of a reproduction. It is one of the main sources, making different type forecasts (birth rate, death rate). The purpose of this work is to analyse change of age structure population of Lithuania for the given period, the great attention is devoted to the process of ageing of the population and to specify the reasons of such change. For the reason of this purpose, the main problems were brought forward: 1. Analysing of changes of age structure of population during the different periods: 1989- 2005; 2001-2005; 2. To estimate changes of age structure urban population; 3. To analyse features of age structure the rural population in a territorial division; 4. To consider dynamics of a level and an index of ageing. Work of the master has been written basing on the statistical data. Considering of a huge number of database in this work, the main conclusions are devoted to age structure the population in 1989-2001 and 2001-2005. There are different age structure the population in cities and villages too. Process of ageing is more active in large cities than in small towns or in... [to full text]

At regional scales climate patterns (e.g., interannual wet-dry cycles) result in high spatial fire synchrony among Southwest forests. However, in the "Sky Island" forests of southeastern Arizona spatial and temporal patterns of fire history and tree age structure at landscape levels (i.e., within mountain ranges) are relatively unknown and therefore the focus of this study. In the Santa Catalina Mountains we reconstructed the fire history on a 2,900-hectare study area with two distinct landscapes, Butterfly Peak (BP) and Rose Canyon (RC) using 2-hectare "points" (i.e., collection areas). The RC landscape was dominated by shallow south-facing aspects and BP was dominated by steep north-facing aspects. Within each landscape, point mean fire intervals (PMFIs) were not significantly different between aspect classes. However, pooled PMFIs were significantly shorter in RC compared to BP. These results show that the fire history at any given point (i.e., 2 hectares or less) was primarily controlled by the broad-scale topography of the encompassing landscape, rather than by the fine-scale topography at that point.Using similar methods we also reconstructed the fire history on Rincon Peak, which is a small isolated mountain range with very step topography. The fire history of the 310-hectare forest area was a mixture of frequent low severity surface fires (from AD 1648 to 1763) and infrequent mixed-severity fires (from AD 1763 to 1867). This mixed-fire regime was probably due to a combination of climatic variability, the small area and rugged topography of this mountain range, and complex fuel arrangements. The distinct fire histories from these two study areas provided natural age structure experiments that indicated tree age cohorts (i.e., higher than expected tree establishment pulses) occurred during periods of reduced fire frequencies. In some instances these periods were likely caused by climatic variability (e.g., a wet and/or cool early 1800s) creating synchronous age cohorts across the region. At other times, extended fire intervals were a function of local topography (e.g., 1763-1819 in the northern half of Rincon Peak). Overall, these studies demonstrated that landscape and climatic variations combine to produce complex spatial and temporal variations in fire history and tree age structures.

The effect of changes in age structure on economic growth has been widely studied in the demography and population economics literature. The beneficial effect of changes in age structure after a decrease in fertility has become known as the "demographic dividend." In this article, we reassess the empirical evidence on the associations among economic growth, changes in age structure, labor force participation, and educational attainment. Using a global panel of countries, we find that after the effect of human capital dynamics is controlled for, no evidence exists that changes in age structure affect labor productivity. Our results imply that improvements in educational attainment are the key to explaining productivity and income growth and that a substantial portion of the demographic dividend is an education dividend. (authors' abstract)

<p>The two papers presented in this thesis focus on population genetic study on freshwater pearl mussel populations in Sweden, using RAPD method. In paper I, I examine genetic variation within and between 5 populations in a single drainage area in south western Sweden. In paper II, I study the evolutionary relationship, and how genetic variation is related to population size, age structure and geographic isolation in 14 populations of freshwater pearl mussel in south central Sweden. In both papers I and II, I found that genetic variation was larger than found in previous studies using other techniques, and variation was larger between than within populations. I did not found any correlation between geographic and genetic distance, which indicates that mussel populations have been adapted locally to environmental factors in a relatively short time. In paper I, I found that genetic distance between populations was greater than found in other studies, despite small geographic distances. In paper II, I found that populations were highly differentiated indicating little gene flow between them. There was no significant positive relation between genetic variation and population size or age structure but there was a significant positive relation between mean age and population size indicating that many populations have gone through bottlenecks recently.</p>

The two papers presented in this thesis focus on population genetic study on freshwater pearl mussel populations in Sweden, using RAPD method. In paper I, I examine genetic variation within and between 5 populations in a single drainage area in south western Sweden. In paper II, I study the evolutionary relationship, and how genetic variation is related to population size, age structure and geographic isolation in 14 populations of freshwater pearl mussel in south central Sweden. In both papers I and II, I found that genetic variation was larger than found in previous studies using other techniques, and variation was larger between than within populations. I did not found any correlation between geographic and genetic distance, which indicates that mussel populations have been adapted locally to environmental factors in a relatively short time. In paper I, I found that genetic distance between populations was greater than found in other studies, despite small geographic distances. In paper II, I found that populations were highly differentiated indicating little gene flow between them. There was no significant positive relation between genetic variation and population size or age structure but there was a significant positive relation between mean age and population size indicating that many populations have gone through bottlenecks recently.

A Study of the Influence of Enterprise Pensions System on Work Force Age Structure and Work Force Utilization in China Steel Corporation THESIS ABSTRACT The key factor of whether an enterprise can achieve its operation goal is effective utilization and management of human resources. In order to accomplish the goal of effective recruitment, training, utilization and retaining of human resources, an enterprise should monitor and control the status of the environmental change and enterprise development, and plan, improve and implement its human resource management system constantly. China Steel Corporation (CSC) was officially registered on December 3, 1971. As of the end of January, 2000, CSC has 8,973 employees with an average age of 43.97. Among them, 5,617 or 62% of its total employees are between 40 to 50 years. The aging statistic indicates a relatively narrow age spectrum, which results in the over concentration of education degrees, ages and years in services of its employees, i.e., the homogeneity of its human resources. Once the business expansion of the enterprise becomes slow or even remains stagnant, its human resources can not be effectively dispersed or reallocated, which indicates limited promotion opportunities due to a lower turnover rate. Consequently, the company development is eligible to its canyon period, and growth is ended; then human aging becomes deteriorating. However, the legal labor pensions system is of very limited influence to improve CSC worker turnover rate and age structure. This pension system can not solve the current problem. Thus, we analyze and examine feasible human resource strategies in CSC from the work force utilization aspect. We also recommend a series of strategic thinking, e.g. its internal retirement adjustment, preferential early retirement, CSC Group work force utilization, business outsourcing, inner createpreneur help, etc., to improve the workers' age structure effectively, keep excellent replacement, activate work force, and enhance human resource utilization efficiently. By doing so, CSC will constantly upgrade its competitive advantage, and ensure its continuous operation.

Scientific knowledge on a population's religious composition is essential to understand the challenges faced by societies today. It arises in opposition to speculations about the actual size of religious groups that have been increasingly present in the public discourse in Europe for many years. This is particularly the case in Austria where the flows of refugees and migrants coming from the Middle East and Afghanistan have intensified since 2011 and culminated in 2015. These sparked a debate on the actual size of the Muslim population in Austria. This study fills the gap by presenting estimates of the religious composition for 2016 and projections until 2046 based on several scenarios related to the three major forces affecting the religious composition: migration (including asylum seekers), differential fertility and secularisation. The projections demonstrate that religious diversity is bound to increase, mostly through immigration and fertility. We further focus on the role and implications of international migration on the age and sex composition within the six religious groups: Roman Catholics, Protestants, Orthodox, Muslims, other religions and unaffiliated. We find that the volume and composition of international migrants can maintain youthful age compositions in minority religions - Muslims and Orthodox. Sustained immigration leads to slower ageing but does not stop or reverse the process. The disparity between older majority and younger minority religious groups will further increase the cultural generation gap.