scholarly journals Correlations in fertility across generations: can low fertility persist?

2014 ◽  
Vol 281 (1779) ◽  
pp. 20132561 ◽  
Author(s):  
Martin Kolk ◽  
Daniel Cownden ◽  
Magnus Enquist

Correlations in family size across generations could have a major influence on human population size in the future. Empirical studies have shown that the associations between the fertility of parents and the fertility of children are substantial and growing over time. Despite their potential long-term consequences, intergenerational fertility correlations have largely been ignored by researchers. We present a model of the fertility transition as a cultural process acting on new lifestyles associated with fertility. Differences in parental and social influences on the acquisition of these lifestyles result in intergenerational correlations in fertility. We show different scenarios for future population size based on models that disregard intergenerational correlations in fertility, models with fertility correlations and a single lifestyle, and models with fertility correlations and multiple lifestyles. We show that intergenerational fertility correlations will result in an increase in fertility over time. However, present low-fertility levels may persist if the rapid introduction of new cultural lifestyles continues into the future.

2021 ◽  
Vol 13 (11) ◽  
pp. 6313
Author(s):  
Ramona Ciolac ◽  
Tiberiu Iancu ◽  
Ioan Brad ◽  
Tabita Adamov ◽  
Nicoleta Mateoc-Sîrb

The agritourism activity can be a characteristic reality of the present, considering rural area’s sustainability, being at the same time a business reality for rural entrepreneurs and a “must have” for rural communities that have tourism potential. It is a form of tourism, through which the tourist can receive a qualitative product at a reasonable price, but also a field that can ensure sustainable development over time, being at the same time environmentally friendly. The purpose of this scientific paper is to identify the aspects that make agritourism “a possible business reality of the moment”, for Romanian rural area’s sustainability. We take into account the following areas: Bran-Moieciu area—considered “the oldest” in terms of agritourism experience, and Apuseni Mountains area, with a great inclination and potential for this activity. The study conducted for these two areas is focused on several aspects: the degree of involvement in agritourism activities, considering the number of years and managerial experience, the analysis of the types of activities/experiences offered by agritourism structures, the identification of the main reasons/motivations for the orientation towards agritourism and the manner in which this field is perceived. Aspects related to the marketing-finance part of the agritourism business are also taken into account: customers, distribution channels, financial sources, shortcomings observed by agritourism business owners and possible action directions so as to improve the activity/agritourism product. Agritourism may be “a possible business reality of the moment” for the studied areas and not only, but in the future, the entrepreneur/farmer must be constantly updated because of the changing situations that appear on the market, be able to make sustainable decisions for his/her own business, which in the future will ensure its viability and obviously its long-term profitability and development, and in the same time rural area’s sustainability.


Polar Record ◽  
2017 ◽  
Vol 53 (4) ◽  
pp. 436-447
Author(s):  
Wygene Chong

ABSTRACTThe Antarctic Treaty System (ATS) has provided a peaceful framework for governing the continent over many decades, in spite of seven extant territorial claims. However, its method of freezing these claims has been criticised for being short-sighted and ineffective in providing a long-term solution. This paper argues to the contrary. It undertakes a brisk analysis of different categories of alternatives: global commons, absolute sovereignty, restricted sovereignty and shared sovereignty. After dismissing each category for various reasons, it promotes the reform of the existing ATS, in which a long-term vision and modified chairmanship structure provide stronger leadership and more effective implementation. Essentially, it holds that the primary reason there is criticism of the system is because it is not functioning as well as it might be. The paper not only contends that a developed ATS is an achievable aim, but that it could eventually develop into a restricted, shared sovereignty governance framework. That form of governance, which would emerge over time, could be a more durable solution that resolves the competing territorial claims. In this way, the paper charts a potential pathway for the future of Antarctic governance. This path begins, however, with a reformed ATS.


Author(s):  
I.A. Yanchin

В работе рассматривается метод оценки маршрута судна с точки зрения безопасности и оптимальности. Оценка выполняется за счёт вычисления характеристических коэффициентов, которые описывают свойства маршрута, важные для оценки этих качеств. Также в работе даётся описание метода прогнозирования дальнейшего маршрута судна на основе предписанного маршрута рейса и информации о существующем отклонении фактического маршрута от предписанного. На основе прогнозирования дальнейшего маршрута, и с использованием характеристических коэффициентов, становится возможным анализ долгосрочного влияния отклонения фактического маршрута от предписанного. Маршрут рассматривается как динамическая характеристика судна, эволюционирующая с течением времени. Обсуждаются особенности развития маршрута судна при стремлении к стабильному либо катастрофичному состоянию с позиций современной теории катастроф. Геометрическая интерпретация эволюционной динамики предусматривает использование когнитивных образов. В работе приводится анализ произошедшей аварии круизного судна Costa Concordia с использованием предложенного метода с целью исследования влияния изменения маршрута на безопасность рейса. Выполняется сравнение предписанного маршрута с фактическим.The paper presents a method to analyze a ships route in terms of safety and optimality. The route is examined using the characteristic coefficients that represent routes properties essential for assessment of these aspects. The paper also presents a method to estimate the future route based on the prescribed route and the existing discrepancy between the actual route and the prescribed one. With such estimation technique and using the characteristic coefficients it is possible to determine the long-term effects of the discrepancy. The route is considered as a dynamic characteristic of the ship, evolving over time. Peculiarities of the development of the ships route when striving for a stable or catastrophic state from the standpoint of the modern catastrophe theory are discussed. A geometric interpretation of evolutionary dynamics involves the use of cognitive images. As an example, the paper provides analysis of the Costa Concordias accident using the described method in order to determine the effects of the route discrepancy. A comparison is made of the prescribed route with the actual one that the crew planned to move.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alba Viana-Lora ◽  
Antoni Domènech ◽  
Aaron Gutiérrez

PurposeThis paper aims to review conceptual and empirical studies that analyse the impact of the pandemic on mobility and tourism behaviour at destinations in order to identify proposals, forecasts and recommendations to guide the future research agenda on the subject.Design/methodology/approachThis study used a systematic literature review to synthesise information from scientific articles published in journals indexed in the Web of Science database related to tourism mobility at destinations during the COVID-19 pandemic.FindingsThis article found that, according to the existing literature, the COVID-19 pandemic is acting as a catalyst for the sustainable transition of tourism. Although the findings reveal a lack of empirical research on the impact of the pandemic on tourism mobility at destinations, the article synthesizes the short- and long-term impacts of the pandemic and sets out the future research agenda on tourist mobility at destinations.Originality/valueTo the best of the authors' knowledge, this is the first systematic review of the impact of the pandemic on mobility and tourism behaviour at destinations that attempts to describe the emerging challenges and the agenda for future research.


Author(s):  
Vijitashwa Pandey ◽  
Zissimos P. Mourelatos ◽  
Annette Skowronska

Many repairable systems degrade with time and are subjected to time-varying loads. Their characteristics may change over time considerably, making the assessment of their performance and hence their design difficult. To address this issue, we introduce in this paper the concept of flexible design of repairable systems under time-dependent reliability considerations. In flexible design, the system can be modified in the future to accommodate uncertain events. As a result, regardless of how uncertainty resolves itself, a modification is available that will keep the system close to optimal provided failure events have been properly characterized. We discuss how flexible design of repairable systems requires a fundamentally new approach and demonstrate its advantages using the design of a hydrokinetic turbine. Our results show that long-term metrics are improved when time-dependent characteristics and flexibility are considered together.


Koedoe ◽  
1999 ◽  
Vol 42 (1) ◽  
Author(s):  
A.M. Woodd

An age-structured demographic model of the growth of the Addo elephant population was developed using parameters calculated from long-term data on the population. The model was used to provide estimates of future population growth. Expansion of the Addo Elephant National Park is currently underway, and the proposed target population size for elephant within the enlarged park is 2700. The model predicts that this population size will be reached during the year 2043, so that the Addo elephant population can continue to increase for a further 44 years before its target size within the enlarged park is attained.


2019 ◽  
Vol 11 (5) ◽  
pp. 1305 ◽  
Author(s):  
Margherita Carlucci ◽  
Ilaria Zambon ◽  
Andrea Colantoni ◽  
Luca Salvati

Empirical studies investigating long-term trends in wildfires’ frequency and severity have been relatively scarce in Europe. Number of fire events, total burnt area and average fire size were studied between 1961 and 2017 in Italy with the aim to identify homogeneous time periods with similar wildfire frequency and severity and correlate them with the background socioeconomic context. Fire attributes had a diverging behavior over time: the number of fires was the highest in the 1970s and the early 1980s; total burnt area was relatively more constant over time with a peak in the 1980s; and, finally, average fire size decreased quite homogeneously from the peak observed in the 1960s and early 1970s. The number of fires and average fire size were significantly influenced by the value of the same variable one year before. Investigating long-term historical outlines of forest fires, a mixed approach based on time-series statistical analysis, multivariate techniques and regressive models intended to define changes in fire regimes and socioeconomic development. In fact, the comparative valuation of the socioeconomic aspects and wildfire trends can reveal a key step to recognizing mitigation and preventive possibilities. Through a multivariate analysis, a substantial difference in the socioeconomic profile can emerge by decade, evidencing a (more or less) rapid socioeconomic development in relation to the evolution of forest fires in Italy.


1999 ◽  
Vol 18 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Lynton Keith Caldwell

As the twentieth century ends, we may identify both constructive and destructive trends that will influence the future of humanity. Which set of trends will dominate the future is uncertain. Attitudes, beliefs, and behaviors all interact to direct the flow of change over time. However, the options and constraints of human life are ultimately fixed by those cosmic elements of the environment over which humans have no control. The modern assumption of a world without end or limits risks collision with that obdurate reality. Facing threats to its long-term survival, humanity is challenged to learn how to build a sustainable future. A successful effort will require a concerted and cooperative effort among all fields of knowledge. This article identifies some of the trends that threaten humanity's future and suggests four lines of action that should be pursued in order to reduce the likelihood that humanity will destroy itself.


2013 ◽  
Vol 9 (4) ◽  
Author(s):  
Colin James

The Treasury’s long-term fiscal projections are designed to inform present-day policy. They draw attention to existing trends and potential future global and national developments in society, demography, politics, technology and the economy, and the fiscal implications of continuing existing policy unchanged through those changes over the next 40 years and beyond. They highlight that the later action is taken to offset an anticipated impact, the greater the policy change may have to be and also potentially the cost, not just in money but also in social cohesion if unusual intergenerational tensions develop as a consequence. But if large adjustments have to be made, even if over time, how might that be done in a representative democracy in which the ultimate decisionmakers, the politicians, are subject to frequent elections in which political folklore tells us the determinant issues are proximate and ‘courageous’ leaders are sacrificed to short-term voter self-interest? 


Stanovnistvo ◽  
2016 ◽  
Vol 54 (2) ◽  
pp. 27-58 ◽  
Author(s):  
Vladimir Nikitovic

After the dissolution of the socialist Yugoslavia (SFRY) in 1991, the quality and availability of demographic and migration statistics in the region as a whole, and especially in some of its parts are deteriorated. In addition, census rounds are not being held regularly throughout the region as of 1991. Thus, producing population projections has become rather challenging in comparison to the period of SFRY. This paper made an effort in order to overcome obstacles in terms of historic data and jump-off projection values for the whole region in accordance with adjusted data from national records. Until 1991, population of the region had been increasing almost linearly. Although SFRY was characterized by significant sub-regional differences in terms of the beginning and the pace of demographic transition, the current total fertility rate throughout the region is below 2.1. The aim of the paper is to consider the long-term implications of low fertility and whether in this respect there would be a demographic homogenization of the region. For that purpose, we relied on the UN WPP2015 model used by the UN Population Division for producing its 2015 World Population Prospects. It enabled several important features from the viewpoint of the main tasks of the paper: the methodologically consistent datasets on main demographic indicators, probabilistic approach for modelling and forecasting fertility and mortality, the opportunity to adjust initial datasets for known issues on data quality (Serbia, Kosovo, Bosnia & Herzeg.), and ability to adjust data distribution according to the former administrative division of SFRY. The last one was of particular importance as it allowed us to take into account the well-known diversity of fertility patterns in Serbia (Vojvodina, Central Serbia and Kosovo), and to make a distinction in projection results between the sub-regions differed by the onset and tempo of fertility transition. The UN concept of post-transition recovery of total fertility rate is lying behind the hypotheses of future TFR. According to the model, Slovenia and Vojvodina has been already entered the post-transitional phase. Central Serbia and Macedonia are first to join them (as of 2020), followed by Croatia and Bosnia & Herzeg. (2025), and Montenegro (2030). However, the fertility transition in Kosovo could last until 2070. The greatest chance (median distribution of the simulated trajectories) is that TFR in the SFRY region will converge to the levels projected for Southern Europe (1.8) in 2100, except in Slovenia (1.89). Hypotheses on migration in deterministic manner were based on the ?migration cycle model? introduced by Fassmann and Reeger (2012), which assume that all of Europe will eventually experience the transition to net immigration. Since the strategic objectives of all governments in the region are consistent when it comes to joining the EU, it is taken as a pivotal condition for a hypothesis on the migration transition. The symbolic turning point in the transition process in the region (2035) implies that the whole region will become the part of the EU by then. Kosovo is assumed to be the only territory not able to achieve the net immigration during The greatest chances (median of the distribution) are that the population in the region of SFRY will be reduced by 16.9% between 2015 and 2055, which puts this region among the ones that are going to experience the strongest decrease (over 15%) in global terms - mainly countries of the former Eastern bloc and Japan. According to the median of prediction intervals, a sharp decline is expected in Vojvodina (31.7%), Cent. Serbia (27.2 %), Bosnia & Herzeg. (22.0%), and Croatia (18.9%), which is similar to the countries that were expected to experience the greatest population decrease in the world by 2050 - Bulgaria, Romania, Ukraine, and Moldova. The region reversal to the historic population maximum of 1990 seems to be not possible even in conditions of the above replacement fertility. A zone of depopulation emerged along the eastern rim of the EU, which, according to the UN model, is the most prominent depopulation zone in global terms. Prediction intervals indicate that by the mid-century, with the exception of Kosovo, only Slovenia has some chances (35%) to maintain the current population size. However, to return to its maximum population by 2100 some chance has only Slovenia (almost 30%), and only minimal Montenegro (8%), and Kosovo (5%). Old-age dependency ratio in the SFRY region is likely to double by the mid-century, while the prediction intervals suggest that even a return to the current unfavourable level is outside of the range of possible outcomes throughout the region. It is the most important long-term demographic implication of low fertility. Yet, that rise has its limits. Therefore, the next four decades will be the most challenging period of getting used to the new demographic reality, which in view of the modern concept of population policy (quality before quantity) is not necessarily bad. One of the conclusions is that the significant increase in the total fertility rate, i.e. up to and around the replacement level of 2.1, which current official projections (Cent. Serbia, Vojvodina, Montenegro, and Croatia) consider as the ultimate objective of population policy, is far beyond the possible outcomes.


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