WorldWideScience

Sample records for single-species population growth

  1. Two Positive Periodic Solutions for a Neutral Delay Model of Single-Species Population Growth with Harvesting

    OpenAIRE

    Fang, Hui

    2012-01-01

    By coincidence degree theory for k-set-contractive mapping, this paper establishes a new criterion for the existence of at least two positive periodic solutions for a neutral delay model of single-species population growth with harvesting. An example is given to illustrate the effectiveness of the result.

  2. Two Positive Periodic Solutions for a Neutral Delay Model of Single-Species Population Growth with Harvesting

    Directory of Open Access Journals (Sweden)

    Hui Fang

    2012-01-01

    Full Text Available By coincidence degree theory for k-set-contractive mapping, this paper establishes a new criterion for the existence of at least two positive periodic solutions for a neutral delay model of single-species population growth with harvesting. An example is given to illustrate the effectiveness of the result.

  3. Global Asymptotic Stability for Discrete Single Species Population Models

    Directory of Open Access Journals (Sweden)

    A. Bilgin

    2017-01-01

    Full Text Available We present some basic discrete models in populations dynamics of single species with several age classes. Starting with the basic Beverton-Holt model that describes the change of single species we discuss its basic properties such as a convergence of all solutions to the equilibrium, oscillation of solutions about the equilibrium solutions, Allee’s effect, and Jillson’s effect. We consider the effect of the constant and periodic immigration and emigration on the global properties of Beverton-Holt model. We also consider the effect of the periodic environment on the global properties of Beverton-Holt model.

  4. On the apllication of single specie dynamic population model | Iguda ...

    African Journals Online (AJOL)

    The Method of mathematical models of Malthus and Verhults were applied on ten years data collected from Magaram Poultry Farm to determine the nature of population growth, population decay or constant ... Keywords: Birth rate, sustainable population, overcrowding, harvesting, independent t-test and one way Anova.

  5. Single species victory in a two-site, two-species model of population dispersion

    Science.gov (United States)

    Waddell, Jack; Sander, Len; Kessler, David

    2008-03-01

    We study the behavior of two species, differentiated only by their dispersal rates in an environment providing heterogeneous growth rates. Previous deterministic studies have shown that the slower-dispersal species always drives the faster species to extinction, while stochastic studies show that the opposite case can occur given small enough population and spatial heterogeneity. Other models of similar systems demonstrate the existence of an optimum dispersal rate, suggesting that distinguishing the species as faster or slower is insufficient. We here study the interface of these models for a small spatial system and determine the conditions of stability for a single species outcome.

  6. on the apllication of single specie dynamic population model 306

    African Journals Online (AJOL)

    pc

    used to compare the predicted values and observed values in order to find out whether there is significant difference between the observed and predicted values using these two models. Keywords: Birth rate, sustainable population, overcrowding, harvesting, independent t-test and ..... 95% confidence interval of the.

  7. A structurally based analytic model of growth and biomass dynamics in single species stands of conifers

    Science.gov (United States)

    Robin J. Tausch

    2015-01-01

    A theoretically based analytic model of plant growth in single species conifer communities based on the species fully occupying a site and fully using the site resources is introduced. Model derivations result in a single equation simultaneously describes changes over both, different site conditions (or resources available), and over time for each variable for each...

  8. In-vitro activity of taurolidine on single species and a multispecies population associated with periodontitis.

    Science.gov (United States)

    Zollinger, Lilly; Schnyder, Simone; Nietzsche, Sandor; Sculean, Anton; Eick, Sigrun

    2015-04-01

    The antimicrobial activity of taurolidine was compared with minocycline against microbial species associated with periodontitis (four single strains and a 12-species mixture). Minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs), killing as well as activities on established and forming single-species biofilms and a 12-species biofilm were determined. The MICs of taurolidine against single species were always 0.31 mg/ml, the MBCs were 0.64 mg/ml. The used mixed microbiota was less sensitive to taurolidine, MIC and the MBC was 2.5 mg/ml. The strains and the mixture were completely killed by 2.5 mg/ml taurolidine, whereas 256 μg/ml minocycline reduced the bacterial counts of the mixture by 5 log10 colony forming units (cfu). Coating the surface with 10 mg/ml taurolidine or 256 μg/ml minocycline prevented completely biofilm formation of Porphyromonas gingivalis ATCC 33277 but not of Aggregatibacter actinomycetemcomitans Y4 and the mixture. On 4.5 d old biofilms, taurolidine acted concentration dependent with a reduction by 5 log10 cfu (P. gingivalis ATCC 33277) and 7 log10 cfu (A. actinomycetemcomitans Y4) when applying 10 mg/ml. Minocycline decreased the cfu counts by 1-2 log10 cfu independent of the used concentration. The reduction of the cfu counts in the 4.5 d old multi-species biofilms was about 3 log10 cfu after application of any minocycline concentration and after using 10 mg/ml taurolidine. Taurolidine is active against species associated with periodontitis, even within biofilms. Nevertheless a complete elimination of complex biofilms by taurolidine seems to be impossible and underlines the importance of a mechanical removal of biofilms prior to application of taurolidine. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. The Bifurcation and Control of a Single-Species Fish Population Logistic Model with the Invasion of Alien Species

    Directory of Open Access Journals (Sweden)

    Yi Zhang

    2014-01-01

    Full Text Available The objective of this paper is to study systematically the bifurcation and control of a single-species fish population logistic model with the invasion of alien species based on the theory of singular system and bifurcation. It regards Spartina anglica as an invasive species, which invades the fisheries and aquaculture. Firstly, the stabilities of equilibria in this model are discussed. Moreover, the sufficient conditions for existence of the trans-critical bifurcation and the singularity induced bifurcation are obtained. Secondly, the state feedback controller is designed to eliminate the unexpected singularity induced bifurcation by combining harvested effort with the purification capacity. It obviously inhibits the switch of population and makes the system stable. Finally, the numerical simulation is proposed to show the practical significance of the bifurcation and control from the biological point of view.

  10. Impact of environmental colored noise in single-species population dynamics

    Science.gov (United States)

    Spanio, Tommaso; Hidalgo, Jorge; Muñoz, Miguel A.

    2017-10-01

    Variability on external conditions has important consequences for the dynamics and the organization of biological systems. In many cases, the characteristic timescale of environmental changes as well as their correlations play a fundamental role in the way living systems adapt and respond to it. A proper mathematical approach to understand population dynamics, thus, requires approaches more refined than, e.g., simple white-noise approximations. To shed further light onto this problem, in this paper we propose a unifying framework based on different analytical and numerical tools available to deal with "colored" environmental noise. In particular, we employ a "unified colored noise approximation" to map the original problem into an effective one with white noise, and then we apply a standard path integral approach to gain analytical understanding. For the sake of specificity, we present our approach using as a guideline a variation of the contact process—which can also be seen as a birth-death process of the Malthus-Verhulst class—where the propagation or birth rate varies stochastically in time. Our approach allows us to tackle in a systematic manner some of the relevant questions concerning population dynamics under environmental variability, such as determining the stationary population density, establishing the conditions under which a population may become extinct, and estimating extinction times. We focus on the emerging phase diagram and its possible phase transitions, underlying how these are affected by the presence of environmental noise time-correlations.

  11. [Population Growth and Development].

    Science.gov (United States)

    Clausen, A. W.

    Rapid population growth as a central development problem, the proper domain of government in reducing population growth, and effective measures which can be taken to reduce fertility are examined. Rapid population growth puts a brake on development because it exacerbates the difficult choice between higher consumption now and the investment needed…

  12. Population growth and economic growth.

    Science.gov (United States)

    Narayana, D L

    1984-01-01

    This discussion of the issues relating to the problem posed by population explosion in the developing countries and economic growth in the contemporary world covers the following: predictions of economic and social trends; the Malthusian theory of population; the classical or stationary theory of population; the medical triage model; ecological disaster; the Global 2000 study; the limits to growth; critiques of the Limits to Growth model; nonrenewable resources; food and agriculture; population explosion and stabilization; space and ocean colonization; and the limits perspective. The Limits to Growth model, a general equilibrium anti-growth model, is the gloomiest economic model ever constructed. None of the doomsday models, the Malthusian theory, the classical stationary state, the neo-Malthusian medical triage model, the Global 2000 study, are so far reaching in their consequences. The course of events that followed the publication of the "Limits to Growth" in 1972 in the form of 2 oil shocks, food shock, pollution shock, and price shock seemed to bear out formally the gloomy predictions of the thesis with a remarkable speed. The 12 years of economic experience and the knowledge of resource trends postulate that even if the economic pressures visualized by the model are at work they are neither far reaching nor so drastic. Appropriate action can solve them. There are several limitations to the Limits to Growth model. The central theme of the model, which is overshoot and collapse, is unlikely to be the course of events. The model is too aggregative to be realistic. It exaggerates the ecological disaster arising out of the exponential growth of population and industry. The gross underestimation of renewable resources is a basic flaw of the model. The most critical weakness of the model is its gross underestimation of the historical trend of technological progress and the technological possiblities within industry and agriculture. The model does correctly emphasize

  13. Rapid population growth.

    Science.gov (United States)

    1972-01-01

    At the current rate of population growth, world population by 2000 is expected to reach 7 billion or more, with developing countries accounting for some 5.4 billion, and economically advanced nations accounting for 1.6 billion. 'Population explosion' is the result of falling mortality rates and continuing high birth rates. Many European countries, and Japan, have already completed what is termed as demographic transition, that is, birth rates have fallen to below 20 births per 1000 population, death rates to 10/1000 population, and annual growth rates are 1% or less; annual growth rates for less developed countries ranged from 2 to 3.5%. Less developed countries can be divided into 3 groups: 1) countries with both high birth and death rates; 2) countries with high birth rates and low death rates; and 3) countries with intermediate and declining birth rates and low death rates. Rapid population growth has serious economic consequences. It encourages inequities in income distribution; it limits rate of growth of gross national product by holding down level of savings and capital investments; it exerts pressure on agricultural production and land; and it creates unemployment problems. In addition, the quality of education for increasing number of chidren is adversely affected, as high proportions of children reduce the amount that can be spent for the education of each child out of the educational budget; the cost and adequacy of health and welfare services are affected in a similar way. Other serious consequences of rapid population growth are maternal death and illness, and physical and mental retardation of children of very poor families. It is very urgent that over a billion births be prevented in the next 30 years to reduce annual population growth rate from the current 2% to 1% per year.

  14. Population growth rates in perfect contraceptive populations.

    Science.gov (United States)

    Udry, J R; Bauman, K E; Chase, C L

    1973-07-01

    Abstract Eventually, world population must cease to grow. In many countries attempts are made to decrease population growth by providing family planning services to all who want to prevent pregnancies. In this paper we use the concept 'perfect contraceptive population',(1) - a population in which no unwanted births occur - to derive estimates of the maximum contribution that prevention of unwanted births might make toward attaining a zero rate of natural increase in population.

  15. Population growth and economic growth: a reconsideration.

    Science.gov (United States)

    Yip, C K; Zhang, J

    1996-01-01

    The relationship between population growth and development has long been a controversial topic in the economic development literature. Early work by Hoover and Coale and more recent work by Blanchet suggest that high fertility suppresses per capita income growth. However, recent work by Kelley and Srinivasan are ambivalent about such a neo-Malthusian relationship between population growth and economic growth. The authors examine these conflicting positions. They emphasize that the rates of both population growth and income growth are endogenous variables within a general equilibrium framework. An endogenous growth model with endogenous fertility is then developed. It is found that when all exogenous variables are controlled for, there exists an inverse relation between population growth and economic growth. However, when some exogenous factors change, such as an improvement in technological progress, the relation becomes ambiguous. This suggests that the conflicting findings in the literature may be because of the presence of substantial heterogeneity in unobserved variables across countries and over time in cross-country panel data sets.

  16. U.S. Population Growth.

    Science.gov (United States)

    Dillner, Harry

    This autoinstructional lesson deals with the study of man and his environment. No previous experience or learning in this field is required. Emphasis is placed on analysis of population growth and the impact population growth and trends have on natural resource depletion. The behavioral objectives (five) are listed. The study guide for the…

  17. Population Growth: Crisis and Challenge.

    Science.gov (United States)

    Beaton, John R., Ed.; Doberenz, Alexander R., Ed.

    The proceedings of this first annual symposium on population growth considers the consequences of this growth, along with possible means of regulation. Topics of speeches include: Population Outlook in Asia (Irene Taeuber); Malnutrition is a Problem of Ecology (Paul Gyorgy); The Leisure Explosion (E. H. Storey); Effects of Pollution on Population…

  18. Determinants of human population growth.

    Science.gov (United States)

    Lutz, Wolfgang; Qiang, Ren

    2002-09-29

    The 20th century has seen unprecedented growth of the human population on this planet. While at the beginning of the century the Earth had an estimated 1.6 billion inhabitants, this number grew to 6.1 billion by the end of the century, and further significant growth is a near certainty. This paper tries to summarize what factors lie behind this extraordinary expansion of the human population and what population growth we can expect for the future. It discusses the concept of demographic transition and the preconditions for a lasting secular fertility decline. Recent fertility declines in all parts of the world now make it likely that human population growth will come to an end over the course of this century, but in parts of the developing world significant population growth is still to be expected over the coming decades. The slowing of population growth through declining birth rates, together with still increasing life expectancy, will result in a strong ageing of population age structure. Finally, this paper presents a global level systematic analysis of the relationship between population density on the one hand, and growth and fertility rates on the other. This analysis indicates that in addition to the well-studied social and economic determinants, population density also presents a significant factor for the levels and trends of human birth rates.

  19. Population growth and infant mortality

    OpenAIRE

    Fabella, Christina

    2008-01-01

    The relationship between population growth and economic outcomes is an issue of great policy significance. In the era of the Millennium Development Goals, poverty and its correlates have become the compelling issues. Economic growth may not automatically translate into reductions in poverty and its correlates (may not trickle down) if income distribution is at the same time worsening. We therefore investigate the direct effect of population growth on infant mortality for various income catego...

  20. City Population Growth and Economic Growth

    DEFF Research Database (Denmark)

    Freire-Gibb, L. Carlos

    2008-01-01

    This article looks at the relationship between city population growth (intimately related to population proximity), and economic development. The hypothesis is that wherever dynamic and inclusive networks exist, there are more opportunities for economic development in this place. When these types...... of networks choose a tool (project, policy) to implement in the city, success will be more likely. Furthermore, virtuous circles will arise. The author gives an overview of two historical cases in urban growth, in Europe (1200-1800) and the U.S.A. (1800 to today)....

  1. Human Population: Fundamentals of Growth and Change.

    Science.gov (United States)

    Stauffer, Cheryl Lynn, Ed.

    This booklet focuses on eight elements of population dynamics: "Population Growth and Distribution"; "Natural Increase and Future Growth"; "Effect of Migration on Population Growth"; "Three Patterns of Population Change"; "Patterns of World Urbanization"; "The Status of Women";…

  2. Target population growth: zero.

    Science.gov (United States)

    2000-02-01

    The Fifth Session of the Fourth National Council of the China Family Planning Association held in Beijing on December 13, 1999, focused on how to control the number of people in China and improve their quality of life. Family planners also explored ways to decrease the number of babies with birth defects and maternal mortality rate. During the meeting, Zhang Weiqing, minister of the State Family Planning Commission, expressed that they are optimistic about keeping the Chinese population under 1.3 billion before the 21st century. He added that top attention should be paid to providing family planning service (sexual and reproductive counseling) for unmarried young people, laid-off workers, and the transient population in urban areas. In Shenzhen, a special economic zone, 854 family planning offices have been established among 2.8 million temporary residents, these agencies, many of which are led by temporary residents themselves. Lastly, Zhang announced that a draft national law on population and family planning has been finished and the law is expected to be enacted in 3 years.

  3. [Population ethics and growth].

    Science.gov (United States)

    Boim, D

    1988-01-01

    In order to formulate and implement a national demographic policy, various areas of science are called upon; however, since human lives are involved, ethical aspects play an important role not only in broad ideological terms, e.g, concerning overpopulation, but whenever practical decisions affecting technology and human resources are made. The article describes how the Catholic Church proposes certain "utopian" views or interpretations as part of an ethical "dynamism" and plurality needed when addressing the problem of overpopulation. 3 main starting point are defined for the determination of a population ethic: 1) ethics defined in terms of "nature," 2) in terms of the "human person," and 3) in terms of social "dialectic" involvement. The first point stresses the natural order of things as prescribed by God and impugns any birth control method; however, so-called natural birth control methods are allowed. The second point suggests that the human person is ethically center stage, a modernized position taken by the Church in tune with social realities and man's inherent intelligence. The primacy of live and responsibility is stressed as opposed to mere biological processes. Following this view, use of contraceptive, and even sterilization is allowed; however, abortion is excluded, since it means the elimination of a human life. The problem of overpopulation should be solved within the individual or micro-social context. The third point holds that it would be extremely myopic to reduce the position of the Church to advocating exclusively natural birth control methods while excluding social involvement. A "cosmic" view of faith would end putting material well-being before individual personal lives, would alert against egoism disguised as quality of life enhancement, and ultimately result in socially responsible fertility. In conclusion, the Church acknowledges that its contribution to the question of population ethics occurs in a pluralistic society that does not

  4. Canada's population: growth and dualism.

    Science.gov (United States)

    Beaujot, R P

    1978-04-01

    In Canada the current 1.3% population growth rate is causing some concern. Those concerned argue that such a rate of growth in combination with high levels of consumption could jeopardize the country's resource base and its comfortable style of living. Many Canadians are questioning high levels of immigration, for now that the fertility level is below replacement level, net immigration contributes substantially to population growth (over 1/3 in 1976). The growing proportion of non-Europeans among recent immigrants is causing resentment, and, in a tight job market, immigrants are regarded as threats to the World War 2 baby boom cohort who are now at working ages. The baby boom generation also puts stress on housing and health services, and it will increase the need for pension checks as it ages. Although French fertility is no longer high and immigration is no longer dominated by the British, the French group's 200-year struggle to preserve its identity continues on in the current effort of the Quebec government to enforce the use of French language by law within that province. Geography and climate dictate another demographic fact that divides the country and pervades its history. In addition to intense regionalism, uneven population distribution is responsible for 2 other concerns: the rapid growth of several already large cities and depopulation of many small communities. Focus in this discussion is on Canada's population growth in the past and as projected for the future, historical and current fertility, mortality and immigration trends, the search for a new immigration policy, the impact of the baby boom generation on the population's age structure and the problems this creates, and recent shifts in population distribution and in the country's ethnic and linguistic makeup. The population policy proposals evolved thus far involve to a great extent the use of immigration as a lever for achieving given population objectives.

  5. Focus on managing population growth.

    Science.gov (United States)

    Brown, S

    1995-01-01

    For the past 4 decades, the world's population growth has threatened to outstrip the planet's ability to sustain it. According to recent projections, an end to the growth of world population is finally in sight. Dr. Joseph van Arendonk, deputy executive director of the United Nations Population Fund, told an international press conference that population growth is likely to begin falling before the mid-21st century. Currently, some 87 million couples worldwide wish to use contraception but have no access to services. Van Arendonk argued that 4% of overseas aid set aside for population programs would satisfy this unmet need. He also predicted that the average family size in developing countries would stabilize at 2.1 children within the next 55 years if these needs were met. This would still mean a global population of 10 billion in the year 2050, rising to a plateau of 11.6 billion within the following century. In developing countries fertility rates fell from 6.1 to 3.3 children per woman between the mid-1960s and the mid-1980s, while use of contraception increased from 10% to 50%. However, contraceptive users in the developing world must increase from 446 million in 1994 to 603 million in 2005 to keep population growth within such projected limits. The costs of providing the contraception will increase from US $528 million to US $752 million. The contraceptive needs of 603 million users in 2005 will require: 196 million sterilizations, 436 million IUD insertions, 898 million injectables, 12.3 billion cycles of OCs, and 55 billion condoms. To this end, IPPF plans greater accessibility of services, a wider range of effective methods, and the involvement of the male partner.

  6. Population growth and its implications

    Directory of Open Access Journals (Sweden)

    Badii, M. H.

    2005-01-01

    Full Text Available Human populations have grown at an unprecedented rate over the past three centuries. By 2001, the world population stood at 6.2 billion people. If the current trend of 1.4 % per year persists, the population will double in 51years. Most of that growth will occur in the less developed countries of Asia, Africa, and Latin America. There is a serious concern that the number of humans in the world and our impact on the environment will overload the life support systems of the earth. The crude birth rate is the number of births in a year divided by the average population. A more accurate measure of growth is the general fertility rate, which takes into account the age structure and fecundity of the population. The crude birth rate minus the crude death rate gives the rate of natural increase. When this rate reaches a level at which people are just replacing themselves, zero population growth is achieved. In the more highly developed countries of the world, growth has slowed are even reversed in recent years so that without immigration from other areas, population would be declining. The change from high birth and death rates that accompanies in industrialization is called a demographic transition. Many developing nations have already begun this transition. Death rates have fallen, but birth rates remain high. Some demographers believe that as infant mortality drops and economic development progresses so that people in these countries can be sure of secure future, they will complete the transition to a stable population or a high standard living. While larger populations bring many problems, they also may be a valuable resource of energy, intelligence, and enterprise that will make it possible to overcome resource limitation problems. A social just view argues that a more equitable distribution of wealth might reduce both excess population growth and environmental degradation. We have many more options now for controlling fertility than were available

  7. Political economy of population growth.

    Science.gov (United States)

    Mehta, S; Mehta, H S

    1987-01-01

    Tracing the origin of political economy as a class-science, this paper focuses on the political economy of population growth. Exposing the limitations of Malthusian ideas and their invalidity even for the capitalist economies, it discusses the subsequent revival of the Malthusian model during the period of de-colonization and the misinterpretation of the relationship between population growth and development in the developing and developed countries. Taking India, China, and Japan as some case studies, the paper examines the relationship between birth rate levels and some correlates. It elaborates on the Indian experience, emphasizing the association of population growth with poverty and unemployment and lays bare some of the hidden causes of these phenomena. The authors examine some interstate variations in India and identify constraints and prospects of the existing population policy. The paper proposes outlines of a democratic population policy as an integral part of India's development strategy which should recognize human beings not simply as consumers but also as producers of material values. It pleads for 1) restructuring of property relations; 2) bringing down the mortality rates and raising of the literacy levels, especially among females; and 3) improving nutritional levels, as prerequisites for bringing down birth rates.

  8. MPS views on population growth.

    Science.gov (United States)

    1997-09-01

    This article features the different views of Parliament members concerning the need in the reduction of population growth for development sustenance. Population growth would lead to environmental degradation, malnutrition, diseases, and high incidence of poverty. Furthermore, social problems arise like teenage pregnancies, and abuse of young girls. Suggestions on curtailing this problem as suggested by some of the parliament members includes educating people on issues of migration, family planning and reproductive health. Other members suggested on family planning legislation, like in the case of China where population explosion exists. Further, members thought that advocacy for population control such as condom usage targeting to couples having large families should be catered. However, this was denounced by some members as a failure and should not be sanctioned at large family couples but rather to husband with several wives. Finally, a compromised view was directed on population management with poverty alleviation involving the provision of amenities such as water, electricity, good roads, potable water, and income generating activities.

  9. Environmental impact of population growth

    Science.gov (United States)

    Naylor, Rosamond; Matson, Pamela

    Earth's population currently numbers 5.4 billion; even given optimistic assumptions for reduction in growth rates, the number will double by the middle of the next century with most of the increase in the developing countries. Rapid population growth in the developing world raises the fundamental dilemma of how to alleviate chronic hunger and poverty in the short run while preserving the atmosphere and ecosystem services required for long-term human and biospheric sustenance. This dilemma, and the compromises required to solve it, were discussed by twenty-five researchers from five countries at the Aspen Global Change Institute 1992 Summer Science Session III, Food, Conservation, and Global Environmental Change: Is Compromise Possible?, held from August 16 to 28, in Aspen, Colo.

  10. Population growth can be checked.

    Science.gov (United States)

    Shukla, J P

    Since independence, India's population size has doubled. The rate of growth was 2.5% during 1971-81, an increase from the rate of 2.15% observed during the 1951-61 period. The increase indicated that efforts to decrease population growth have not succeeded. The implications with respect to food, housing, clothing, education, and health facilities, which are fundamental to improving the physical quality of life, are severe. This demographic trend is a serious impediment to progress. The population growth is due to a constant birthrate and a sharp decline in mortality. Reducing the birthrate is necessary to reduce the rate of growth. An attitudinal change adopting the norm of family limitation should be encouraged through propaganda, socioeconomic programs, and religious and cultural organizations. Other measures to bring about a decline in the birthrate include: increasing the marriage age, and expanding educational and employment opportunities for women and girls. These measures will require substantial effort and time. Incentives may show more immediate effects. Monetary incentives are not desired because of the possibility of misuse. However the government could assume responsibility for the education and guarantee employment of children of couples who have only one child, and provide free education to children of couples with only 2 children. These incentives are not likely to be misused, can be available to all segments of the population, and involve no immediate large financial burden on the government. In addition, scholarships to the Harijan students should be limited to 2 per family. If these measures are accepted, they could quickly reduce the birth rate.

  11. Population growth and economic development.

    Science.gov (United States)

    Corbridge, S

    1989-01-01

    The Malthusian and neo-Malthusian approaches to the role of population growth in economic development and resource depletion are briefly outlined. Three arguments are then presented that emphasize demographic determinism, empirical evidence, and cause and effect. The author concludes that non-coercive family planning programs may have a role to play in countries that are unable to reduce inequalities, particularly for the poor and for women.

  12. Population Aging and Potential Growth in Asia

    OpenAIRE

    Otsu, Keisuke; Shibayama, Katsuyuki

    2016-01-01

    We study the effects of projected population aging on potential growth in Asian economies over the period 2015–2050. We find that an increase in the share of the population over 64 years of age will significantly lower output growth through decreased labor participation. Population aging can also reduce economic growth through increased labor income taxes and dampened productivity growth.

  13. [Population growth and the environment].

    Science.gov (United States)

    Hogan, D J

    1991-01-01

    The impact of population growth on the enviornment has been extensively researched; it consists of the depletion of resources (agricultural land absorbed by urban expansion, loss of soils, desertification, loss of biodiversity, less availability of minerals, dwindling of petroleum reserves) and the degradation of natural resources (air and water pollution). For politicians, journalists, and environmentalists, population growth is identified as the principal villain, which is a unidirectional and negative opinion. Demography is supposed to examine the negative and positive effects of the environment-population relationship; however, it is postulated that there has not been much produced in the last 2 centuries in this area. Examination of the research literature does not indicate any view that transcends the Malthusian vision, although a few empirical studies exist (Hogan, 1989). Durham (1979) identified the replacement of subsistence agriculture by export-oriented agriculture as the key factor in overpopulation in El Salvador and Honduras that led to migrations and international conflicts. Tudela (1987) related a similar process in the Mexican state of Tabasco, where a period of malnutrition was accompanied by the expansion of export agriculture and nutritional improvements emanated only from recapturing subsistence agriculture. Fearnside (1986) researched the dynamics of the occupation and destruction of Amazonia. However, Kahn and Simon went further and denied the existence of real environmental problems: population is the ultimate resource, and the more minds, the more good ideas and solutions for any problem. However, in all these cases of pure or modified Malthusianism the relation of population/resources is reduced to a unidimensional relationship; and fertility, mortality, migration, marriage, and age structure receive little attention. A prime candidate for the attention of population specialists should be migration and patterns of settlement and their

  14. Population Growth and National Population Policy of India

    Science.gov (United States)

    Thukral, A. K.; Singh, B. P.

    2008-01-01

    The population growth in India may overtake China by the year 2030. The National Population Policy of India targets population stabilization in India by the year 2045. The present paper carries out objective analysis of the population growth in India in terms of change in specific growth. At the present rate of specific growth rate decline, the population by the end of the century will be 2.49 billion. For the population to achieve zero growth by the year 2045, a decline in specific growth rate will have to be achieved at the rate of 0.000428 per year.

  15. Population growth and global warming

    Science.gov (United States)

    Short, R.V.

    2009-01-01

    When I was born in 1930, the human population of the world was a mere 2 billion. Today, it has already reached 6.8 billion, and is projected to reach 9.1 billion by 2050. That is unsustainable. It is slowly beginning to dawn on us that Global Warming is the result of increasing human CO2 emissions, and the more people there are in the world, the worse it will become. Ultimately, it is the sky that will prove to be the limit to our numbers. The developed countries of the world are the most affluent, and also the most effluent, so we must lead by example and contain our own population growth and per capita emissions. We also have a big debt to repay to former colonial territories in Africa, Asia and South America, who desperately need our help to contain their excessive rates of population growth. Belgian and Dutch obstetricians and gynaecologists can play a critical role in this endeavour. After all, we already have a pill that will stop global warming – the oral contraceptive pill. PMID:25478068

  16. Population growth and global warming.

    Science.gov (United States)

    Short, R V

    2009-01-01

    When I was born in 1930, the human population of the world was a mere 2 billion. Today, it has already reached 6.8 billion, and is projected to reach 9.1 billion by 2050. That is unsustainable. It is slowly beginning to dawn on us that Global Warming is the result of increasing human CO2 emissions, and the more people there are in the world, the worse it will become. Ultimately, it is the sky that will prove to be the limit to our numbers. The developed countries of the world are the most affluent, and also the most effluent, so we must lead by example and contain our own population growth and per capita emissions. We also have a big debt to repay to former colonial territories in Africa, Asia and South America, who desperately need our help to contain their excessive rates of population growth. Belgian and Dutch obstetricians and gynaecologists can play a critical role in this endeavour. After all, we already have a pill that will stop global warming - the oral contraceptive pill.

  17. Population and Economic Growth: A Review Essay

    Directory of Open Access Journals (Sweden)

    Marinko Škare

    2015-08-01

    Full Text Available For centuries, scientists from various scientific fields have been leading lively discussions on the (bidirectional relationship between population growth and economic growth. Particular attention was given to the nature of the population growth variable, i.e. whether it is an endogenous or exogenous variable. The goal of this paper is to position this discussion into a historical, empirical and institutional perspective in order to establish population as an important factor for socio-economic prosperity, mostly measured in terms of economic growth. Regardless of ambiguous empirical conclusions about the influence of population growth on economic growth, the political aspect is crucial. Population effect should not be measured only in terms of population growth, measured by the increase in the number of inhabitants. Population is an endogenous variable which is under the influence of culture, values, political processes and industrial structure.

  18. Dispersal and spatial heterogeneity: Single species

    Science.gov (United States)

    DeAngelis, Don; Ni, Wei-Ming; Zhang, Bo

    2016-01-01

    A recent result for a reaction-diffusion equation is that a population diffusing at any rate in an environment in which resources vary spatially will reach a higher total equilibrium biomass than the population in an environment in which the same total resources are distributed homogeneously. This has so far been proven by Lou for the case in which the reaction term has only one parameter, m(x)">m(x)m(x), varying with spatial location x">xx, which serves as both the intrinsic growth rate coefficient and carrying capacity of the population. However, this striking result seems rather limited when applies to real populations. In order to make the model more relevant for ecologists, we consider a logistic reaction term, with two parameters, r(x)">r(x)r(x) for intrinsic growth rate, and K(x)">K(x)K(x) for carrying capacity. When r(x)">r(x)r(x) and K(x)">K(x)K(x) are proportional, the logistic equation takes a particularly simple form, and the earlier result still holds. In this paper we have established the result for the more general case of a positive correlation between r(x)">r(x)r(x) and K(x)">K(x)K(x) when dispersal rate is small. We review natural and laboratory systems to which these results are relevant and discuss the implications of the results to population theory and conservation ecology.

  19. The population factor in economic growth theory

    NARCIS (Netherlands)

    Meilink, H.A.

    1974-01-01

    Reviews briefly the role of population growth in economic growth theory and makes a few critical remarks on the applied methodology and the underlying assumptions. Emphasis is laid on the possible relationships between population and economic growth in the developing countries, but also Malthus'

  20. Solving the Levins' paradox in the logistic model to the population growth

    International Nuclear Information System (INIS)

    Araujo de Oliveira, Evaldo; Pereira de Barros, Vicente; Kraenkel, Roberto Andre

    2011-01-01

    We introduce a new method to improve Markov maps by means of a Bayesian approach. The method starts from an initial map model, wherefrom a likelihood function is defined which is regulated by a temperature-like parameter. Then, the new constraints are added by the use of Bayes rule in the prior distribution. We applied the method to the logistic map of population growth of a single species. We show that the population size is limited for all ranges of parameters, allowing thus to overcome difficulties in interpretation of the concept of carrying capacity known as the Levins paradox.

  1. Solving the Levins' paradox in the logistic model to the population growth

    Energy Technology Data Exchange (ETDEWEB)

    Araujo de Oliveira, Evaldo [Instituto de Matematica e EstatIstica - Universidade de Sao Paulo R. do Matao 1010, 05508-090, Sao Paulo (Brazil); Pereira de Barros, Vicente [Instituto Federal de Educacao, Ciencia e Tecnologia de Sao Paulo Av. Joao Olimpio de Oliveira 1561, 18202-000, Itapetininga (Brazil); Kraenkel, Roberto Andre [Instituto de Fisica Teorica - Universidade Estadual Paulista R. Dr. Bento Teobaldo Ferraz 271, Bloco B, 01140-070, Sao Paulo (Brazil)

    2011-03-01

    We introduce a new method to improve Markov maps by means of a Bayesian approach. The method starts from an initial map model, wherefrom a likelihood function is defined which is regulated by a temperature-like parameter. Then, the new constraints are added by the use of Bayes rule in the prior distribution. We applied the method to the logistic map of population growth of a single species. We show that the population size is limited for all ranges of parameters, allowing thus to overcome difficulties in interpretation of the concept of carrying capacity known as the Levins paradox.

  2. Single-species microarrays and comparative transcriptomics.

    Directory of Open Access Journals (Sweden)

    Frédéric J J Chain

    Full Text Available BACKGROUND: Prefabricated expression microarrays are currently available for only a few species but methods have been proposed to extend their application to comparisons between divergent genomes. METHODOLOGY/PRINCIPAL FINDINGS: Here we demonstrate that the hybridization intensity of genomic DNA is a poor basis on which to select unbiased probes on Affymetrix expression arrays for studies of comparative transcriptomics, and that doing so produces spurious results. We used the Affymetrix Xenopus laevis microarray to evaluate expression divergence between X. laevis, X. borealis, and their F1 hybrids. When data are analyzed with probes that interrogate only sequences with confirmed identity in both species, we recover results that differ substantially analyses that use genomic DNA hybridizations to select probes. CONCLUSIONS/SIGNIFICANCE: Our findings have implications for the experimental design of comparative expression studies that use single-species microarrays, and for our understanding of divergent expression in hybrid clawed frogs. These findings also highlight important limitations of single-species microarrays for studies of comparative transcriptomics of polyploid species.

  3. Population growth: Implications for environmental sustainability ...

    African Journals Online (AJOL)

    The impact of population growth on environment and its implication for survival is an important issue. Although considerable attention has been paid to this problem but systematic studies have been inadequate. Rapid population growth and economic development and daily demand for natural resources for domestic and ...

  4. Environmental degradation, energy consumption, population growth ...

    African Journals Online (AJOL)

    Based on the result, there is no evidence of unidirectional causality running from CO2 emissions and energy consumption to economic growth and strong unidirectional causality running from CO2 emissions, energy consumption and economic growth to population growth was found. The long run and short run estimates ...

  5. Population growth and earth's human carrying capacity.

    Science.gov (United States)

    Cohen, J E

    1995-07-21

    Earth's capacity to support people is determined both by natural constraints and by human choices concerning economics, environment, culture (including values and politics), and demography. Human carrying capacity is therefore dynamic and uncertain. Human choice is not captured by ecological notions of carrying capacity that are appropriate for nonhuman populations. Simple mathematical models of the relation between human population growth and human carrying capacity can account for faster-than-exponential population growth followed by a slowing population growth rate, as observed in recent human history.

  6. Population aging and endogenous economic growth

    OpenAIRE

    Prettner, Klaus

    2010-01-01

    This article investigates the consequences of population aging for long-run economic growth perspectives. We introduce age specific heterogeneity of households into a model of research and development (R&D) based technological change. We show that the framework incorporates two standard specifications as special cases: endogenous growth models with scale e ects and semi-endogenous growth models without scale effects. The introduction of an age structured population implies that aggregate laws...

  7. Critique of zero population growth theory.

    Science.gov (United States)

    Bhattacharya, D

    1993-04-01

    This is a critique of widely held theories concerning the relationship between population growth and economic development. "The central purpose of this paper is to critically analyse the zero population growth movement. The hypotheses of Neo-Malthusian theory or Zero Population Growth and the concept of Population Bomb will be briefly stated in Section 1. Section 2 will discuss the theory of demographic transition. Section 3 will critically examine the validity of the Neo-Malthusian theory of population growth. Our conclusions and recommendations will be stated in Section 4." The author's main contention is that overconsumption in developed countries is the major cause of the deterioration of the environment rather than overpopulation in the developing countries. excerpt

  8. Population growth changes targets for immunization.

    Science.gov (United States)

    Tuljapurkar, S; John, A M

    1995-01-01

    The faster the rate of population growth in developing countries, the less likely it is that current protocols for immunization against measles, rubella, and mumps will eradicate these childhood diseases. Standard protocols (timing, percentage of children to be immunized) do not take into account the rapid rates of population growth in developing countries (3.0% per year on average in sub-Saharan Africa and 2.0% in the rest of Africa, in Latin America, and in Asia, excluding China). Most public health planning models in this area were created based on static infant populations. The World Health Organization advises vaccinating at least 85% of children aged 6 to 9 months, a 3-month immunization window during which maternal antibodies are low (so the vaccination takes) and herd immunity is high (the probability that a child will encounter the disease is low because most children have been immunized). In practice, the immunization window in developing countries is 1 year or more. More susceptible children are present than assumed by the models. A larger number of susceptible babies are added each year during rapid population growth. As the age range for immunization widens, a higher percentage of children must be vaccinated to eradicate disease (chart). The proportion of each birth cohort that must be immunized rises as the population growth rate increases. At zero population growth, 94% must be vaccinated; at population growth rates greater than 3%, 98% must be vaccinated.

  9. Population Growth and Economic and Social Development.

    Science.gov (United States)

    Clausen, A. W.

    1985-01-01

    All evidence shows that fast population growth slows development in the developing countries. It is the combination of social development and family planning that is so powerful in reducing fertility. Governments must act now. (RM)

  10. The end of world population growth

    NARCIS (Netherlands)

    Lutz, W; Sanderson, W; Scherbov, S

    2001-01-01

    There has been enormous concern about the consequences of human population growth for the environment and for social and economic development. But this growth is likely to come to an end in the foreseeable future. Improving on earlier methods of probabilistic forecasting(1), here we show that there

  11. Population growth and development: the Kenyan experience.

    Science.gov (United States)

    Nyamwange, M

    1995-01-01

    Rapid population growth in Kenya and high fertility impacts negatively on economic development. The growth and high fertility results in declines in gross national product, per capita food consumption, and land quality; a high dependency ratio; urban crowding; and inadequate health systems. East Africa has the highest crude birth rates in Africa, and Kenya has the highest birth rate of 54/1000 population in East Africa. The African crude death rate is 50% higher than the world average, but Kenya's death rate is the lowest in East Africa and comparable to North American and European death rates. Kenya has the highest rate of natural increase of about 4%. Population growth rates rose over the decades. Kenya's average population density is well above the sub-Saharan African average and much lower than very high density countries. Population is unequally distributed. Regional densities are widely divergent, and the highest densities in Western province are well above densities in Rwanda and Burundi. Urban growth has increased, as has migration to urban areas. Nairobi has 57% of urban population. Improved health and nutrition have contributed to increased life expectancy. The desired family size is large. The impact of demographic factors on economic conditions is evident in the decline in gross national product per capita growth to under 1% during 1972-88. A slight upswing occurred during 1988-93, but other crises are emerging. Food production has not kept pace with population growth. Production has been low due to serious land degradation, short fallow periods, and traditional farming practices. Population pressure has forced families to shift agriculture onto marginal lands, and desertification has increased. A growing proportion of the population is unemployed or underemployed. Population programs should address the underlying conditions for fertility decline.

  12. Population growth and environmental degradation in Malawi.

    Science.gov (United States)

    Kalipeni, E

    1992-01-01

    Malawi has been ranked by the World Bank as one of the poorest countries in Africa. Malawi's only resources are its people and fertile soil, which comprises about 55% of land area. Environmental degradation and population growth conditions in Malawi were used to illustrate the model of environmental degradation linked to population pressure on land resources and government development strategies that favored large-scale agricultural farms. The result has been deforestation, overgrazing, overuse of land for subsistence, and increased population density. The argument was that population growth in some developing countries has been so rapid that environmental collapse is the result. The theoretical framework linking population growth, environment, and resources emphasized processes: 1) the precursor stage of underlying causes; 2) the problem phase with potential ecological and economic decline; and 3) consequences (environmental decline, reduction in food production systems, and reduction in standard of living). The precursors were identified as an agrarian society, lack of a population policy, and emphasis on large families. The problems were rapid population growth and immigration from Mozambique, which led to increased demand for trees for fuel and consequent deforestation, increased demand for arable land and consequent landlessness, increased investment in livestock and consequent overgrazing, and continued population momentum which was a financial burden to government and resulted in increased labor competition. The ecological consequences were soil erosion, degradation of vegetation, and water supply contamination and decline. Eventually, famines will occur and lead to disease, migration, deserted villages, urbanization, unemployment, ethnic conflicts, and political unrest. Population was estimated at 8.75 million in 1990, with exponential growth expected. Completed family size was 6.6 children per woman. Even replacement fertility would mean growth for 50 more

  13. Population Growth Types in India, 1961-71

    Science.gov (United States)

    Chakravarti, A. K.

    1976-01-01

    An effective means of cartographic representation of India's population growth and its spatial characteristics is the focus of this paper. A population growth index and population growth types are discussed. (Author/ND)

  14. Population growth and sustainable development in China.

    Science.gov (United States)

    Gui, S

    1998-12-01

    This article identifies the adverse impacts of population growth in China and offers suggestions for attaining sustainable development. Although China has below replacement level fertility, population will continue to increase. Chinese demographers project that the total fertility rate will average 2.1 each year until 2010, 2.1 until 2050, or 1.88 until 2010 and 1.6 during 2010-2050 under high, medium, and low variants, respectively. Total population would number 1.69 billion, 1.50 billion, or 1.46 billion under various projections, respectively, by 2050. Continued growth is expected to seriously slow economic development, to hinder improvements in the quality of and full use of human resources, to depress increases in per-capita economic development levels, and to impact on reasonable use of resources and environmental protection. The averting of 5 million births would save 35.5 billion yuan. Population growth has reduced the per-capita share of cultivated land from 0.19 to 0.08 hectares during 1952-95. There are about 150-190 million surplus rural laborers. Registered unemployment in cities was 3.1% in 1997. 11.5 million were laid-off workers. The working-age population will exceed 900 million during 2007-26. China's gross national product (GNP) was the 8th highest in the world in 1990, but its per-capita GNP was in 100th place. China's abundant natural resources are seriously reduced when population is considered. Environmental damage is already evident. Population growth needs to be controlled through family planning, an old-age social security program, and long-term population policies. Society needs healthier births and childbearing and better educated children.

  15. Keynes on population and economic growth.

    Science.gov (United States)

    Toye, J

    1997-01-01

    This article discusses the evolution of Keynes's thinking on population based on an unpublished paper from 1914, "Is the Problem of Population a Pressing and Important One Now?" The paper is reported to have 39 pages, but in fact there are many missing page numbers. Keynes's "Essays in Biography" (1933) follows the basic structure and much of the verbal detail of the first 16 pages of "Population." Chapter 2 of the "Economic Consequences of the Peace" discusses the key ideas of "Population." The passages in "Population" and Chapter 2 were probably the sources of a fierce controversy in 1923-24 between Keynes and W.H. Beveridge over Keynes' neo-Malthusianism. "Population" was the basis for the three themes that were central to Keynes's writing on population. Keynes's framework shifted from a global perspective in "Population" to a progressively narrower focus in the 1930s on England and Wales. Keynes was stronger in his advocacy of birth control in "Population" compared to later writings. Keynes was concerned about the quality of population but disagreed on the methods of achieving this. Keynes argued that 75% of the world was not subject to Malthusian dynamics, and the other 25% had developed technology to relieve population pressure. "Population" sketches out the rudiments of the welfare implications of the great divide between North and South population growth rates. Keynes assumes that overpopulation in the South will be compensated for by the international market without consideration of income deficits. Keynes argues against pronatalism. The 1933 essay shows Keynes shift away from Malthus as population expert to Malthus as political economist. By 1937, Keynes had recanted and was very aware of the uncertainty of the economy. The author believes that it is unfortunate that this 1913-14 manuscript remains unknown and, if known, misunderstood.

  16. Population growth in Shanghai and its characteristics.

    Science.gov (United States)

    Zhang, K

    1985-07-01

    There has been an astonishing change in Shanghai's natural population growth over the past 34 years, with a significant difference between urban and suburban areas. In 1954, the birth rate reached as high as 52.6/1000 and the death rate dropped as low as 7.1/1000, the natural growth rate being 45.4/1000. The substantial decline in the rate of natural increase in Shanghai is due to the enormous achievements of family planning programs. In 1983, the 1-child rate of Shanghai areas was 96.56%, with that in urban areas reaching 99.36% and that in rural areas 92.4%. In the last decade, with the development of industrial production, several satellite cities have been built, attracting some of the urban residents from the city proper. The 5 characteristics relating to Shanghai's population growth are: 1) population density is high and population distribution is uneven; 2) fertility declined drastically in the 1970s; 3) the proportion of young is declining and the proportion of aged is increasing; 4) the mortality has been declining steadily, resulting in a longer life expectancy; and 5) the sex ratio has evened out since the liberation when males greatly outnumbered females. These factors point out the arduous task for family planning in the coming years. The enormous population and the increasing number of young people at child bearing ages point out the necessity of carrying on the family planning program.

  17. On the theory of global population growth

    International Nuclear Information System (INIS)

    Kapitza, Sergei P

    2010-01-01

    Ours is an epoch of global demographic revolution, a time of a rapid transition from explosive population growth to a low reproduction level. This, possibly the most momentous change ever witnessed by humankind has, first and foremost, important implications for the dynamics of population. But it also affects billions of people in all aspects of their lives, and it is for this reason that demographic processes have grown into a vast problem, both globally and in Russia. Their fundamental understanding will to a large extent impact the present, the short-term future following the current critical epoch, the stable and uniform global development and its priorities, and indeed global security. Quantitative treatment of historical processes is reached using the phenomenological theory of mankind's population growth. This theory relies on the concepts and methods of physics and its conclusions should take into account the ideas of economics and genetics. (interdisciplinary physics)

  18. Population structure of Bactrocera dorsalis s.s., B. papayae and B. philippinensis (Diptera: Tephritidae) in southeast Asia: evidence for a single species hypothesis using mitochondrial DNA and wing-shape data.

    Science.gov (United States)

    Schutze, Mark K; Krosch, Matthew N; Armstrong, Karen F; Chapman, Toni A; Englezou, Anna; Chomič, Anastasija; Cameron, Stephen L; Hailstones, Deborah; Clarke, Anthony R

    2012-07-30

    Bactrocera dorsalis s.s. is a pestiferous tephritid fruit fly distributed from Pakistan to the Pacific, with the Thai/Malay peninsula its southern limit. Sister pest taxa, B. papayae and B. philippinensis, occur in the southeast Asian archipelago and the Philippines, respectively. The relationship among these species is unclear due to their high molecular and morphological similarity. This study analysed population structure of these three species within a southeast Asian biogeographical context to assess potential dispersal patterns and the validity of their current taxonomic status. Geometric morphometric results generated from 15 landmarks for wings of 169 flies revealed significant differences in wing shape between almost all sites following canonical variate analysis. For the combined data set there was a greater isolation-by-distance (IBD) effect under a 'non-Euclidean' scenario which used geographical distances within a biogeographical 'Sundaland context' (r(2) = 0.772, P Bactrocera dorsalis s.s., B. papayae and B. philippinensis likely represent one species structured around the South China Sea, having migrated from northern Thailand into the southeast Asian archipelago and across into the Philippines. No migration is apparent between the Philippines and Taiwan. This information has implications for quarantine, trade and pest management.

  19. Impact of demographic policy on population growth.

    Science.gov (United States)

    Podyashchikh, P

    1968-01-01

    Various bourgeois theories, including the reactionary Malthusianism and its variants, challenge the Marxist-Leninist revolutionary theory on the growth of population. Bourgeois science maintains that unchanging biological laws of proliferation form the foundation of social life. Malthus, in his "An Essay on the Principle of Population," contends that population increases in a geometric rate, while means of subsistence tend to increase only in an arithmetic rate: neither the way of production nor social conditions but this law of nature in control of proliferation had been the cause of overpopulation, which again leads to misery, hunger, and unemployment. From this follows the possible conclusion that the working classes should be concerned not about how to change the social order but how to reduce the number of childbirths. Progressive science views the laws of social life in a totally different way. Marxism-Leninism teaches that population size, despite the markedly important role played by it in historical progress, fails to represent that main force of social progress which determines the mode of production and of the distribution of material goods, but just the reverse: the mode of production determines the growth of population, the changes in its density and composition. Marxism-Leninism teaches that each historical stage of production (slavery, feudalism, capitalism) has its own special, historically valid demographic law. Bourgeois science maintains that humankind faces an absolute overpopulation caused by the means of production lagging behind the growth of population. Actually this is only a relative overpopulation due to the fact that capitalistic production is subjected to the interests of increasing capitalistic profit and not to those of meeting the demands of population. In socialist countries, production is incessantly developing and expanding, and employment of the entire productive population is ensured. Consequently, the problem of relative

  20. Population structure of Bactrocera dorsalis s.s., B. papayae and B. philippinensis (Diptera: Tephritidae in southeast Asia: evidence for a single species hypothesis using mitochondrial DNA and wing-shape data

    Directory of Open Access Journals (Sweden)

    Schutze Mark K

    2012-07-01

    Full Text Available Abstract Background Bactrocera dorsalis s.s. is a pestiferous tephritid fruit fly distributed from Pakistan to the Pacific, with the Thai/Malay peninsula its southern limit. Sister pest taxa, B. papayae and B. philippinensis, occur in the southeast Asian archipelago and the Philippines, respectively. The relationship among these species is unclear due to their high molecular and morphological similarity. This study analysed population structure of these three species within a southeast Asian biogeographical context to assess potential dispersal patterns and the validity of their current taxonomic status. Results Geometric morphometric results generated from 15 landmarks for wings of 169 flies revealed significant differences in wing shape between almost all sites following canonical variate analysis. For the combined data set there was a greater isolation-by-distance (IBD effect under a ‘non-Euclidean’ scenario which used geographical distances within a biogeographical ‘Sundaland context’ (r2 = 0.772, P r2 = 0.217, P beast analysis provided a root age and location of 540kya in northern Thailand, with migration of B. dorsalis s.l. into Malaysia 470kya and Sumatra 270kya. Two migration events into the Philippines are inferred. Sequence data revealed a weak but significant IBD effect under the ‘non-Euclidean’ scenario (r2 = 0.110, P  Conclusions Bactrocera dorsalis s.s., B. papayae and B. philippinensis likely represent one species structured around the South China Sea, having migrated from northern Thailand into the southeast Asian archipelago and across into the Philippines. No migration is apparent between the Philippines and Taiwan. This information has implications for quarantine, trade and pest management.

  1. Effects of the Global Population Growth

    Directory of Open Access Journals (Sweden)

    Voiculeţ Alina

    2017-01-01

    Full Text Available The demographic factor is not purely natural. It is a social body that has its own structure andis manifested through a series of processes that make up its movement: birth rate, death rate,longevity, migration etc. All these processes depend on the social and economic environment inwhich people live. The growth of the world's population will have multiple effects on theenvironment, the economy and society as a whole.

  2. Population growth in S. E. Asia.

    Science.gov (United States)

    Athak, G S; Narain, J P

    1976-01-01

    In opening remarks before the Conference on Population Growth and Human Development (November 19-22, 1973) Pathak said India must find human solutions to the population problems which are essentially the problems of ordinary men and women. Family limitation decisions should always be voluntary. Population policy must also always be an integral part of the total development strategy. There has already been a good deal of international cooperation in the restricted field of population assistance; now there must be broader cooperation in the perspective of social and economic development. In a valedictory address Narain, lead of the Sarvodaya Movement, indicated his view of the population problem was different from Ghandi's. He felt voluntary organizations which were mobile and committed to the service of the people were more able to achieve results than government agencies. The conference then adopted the following resolutions: 1) raise agricultural production by increasing irrigation and providing necessary communication networks; 2) integrate health and family planning services; 3) provide functional education; 4) make cheap credit available; 5) increase employment opportunities by encouraging village industry. Safe, simple, acceptable family planning methods are needed. Research also is needed to investigate the cultural determinants of family size and fertility patterns. In addition, micro-projects for raising the economic level of villages should avoid the pitfalls of macro-projects and make sure the benefits are quickly apparent to the people affected.

  3. Population ageing alongside health care spending growth

    Directory of Open Access Journals (Sweden)

    Jakovljević Mihajlo

    2017-01-01

    Full Text Available The Silver Tsunami or population ageing has become a globally widespread phenomenon. The purpose of this review is to observe its dynamics and consequences from a local Balkan perspective. The main drivers of this unique demographic evolution are extended longevity, improved early childhood survival, absorption of women into the labor markets, and consequences of sexual revolution leading to falling female fertility. This process lasting well over a century is taking its toll on contemporary societies. Major side effects are shrinking young labor force and growing pool of elderly and retired citizens in many countries. This equation tends to worsen further in the future threatening long-term financial sustainability of public social and health insurance funds. Notable health expenditure growth, accelerating worldwide since the 1960s, is to a large degree attributable to ageing itself. Growing share of senior citizens increases demand for medical services and costs of health care provision. Home-based care provided by the family caregivers presents another important reality putting a huge burden on modern communities. Serbs are no exception in this landscape. Historical demographic evolution of this nation gives a clear evidence of advanced and accelerated ageing, which is well documented in post-World War II era. This synthesis of rich published evidence shows clear upward parallel trend between the pace of population aging and the growth of health expenditure. National authorities shall be forced to consider reform of the current health care financing pattern inherited from the demographic growth era. This might be the only way to smooth out the impact of population ageing on the financial sustainability of the health system and long-term medical care in Serbia. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI 175014

  4. Population growth, demographic change, and cultural landscapes.

    Science.gov (United States)

    Woodgate, G; Sage, C

    1994-01-01

    The inclusion of both ecological and socioeconomic components within landscapes makes possible the perception of the hierarchical character of landscape organization. A research approach is needed to conceptualize cultural landscapes as the product of interaction between society and nature. Richard Norgaard's 1984 paper on coevolutionary agricultural development attempts to meet this challenge. Coevolution is the interactive synthesis of natural and social mechanisms of change that characterize the relationship between social systems and ecosystems. The relationship between population, consumption, and environmental changes is complex. Currently industrialized countries present the biggest threat to global environmental resources. The issue of carrying capacity is the corollary of population and the environment. It is primarily the technological factor rather than population that needs to be controlled. The relationship between rich and poor countries is determined by superior economic power. An analysis of landscape change is made, tracing the coevolution of society and environment from the end of the feudal era and making comparisons with continental Europe. Over the years since 1945 the need to realize potential economies of scale has resulted in a wholesale loss of woodlands, hedgerows, and small ponds in the UK. In a global context the likely impacts of population growth and demographic change on landscapes will be influenced by such socioeconomic factors as technology and affluence; policies that ignore cause and effect; and the traditional tendency to treat the environment as a waste repository and a supply depot.

  5. [African population growth: status and prospects].

    Science.gov (United States)

    Tabutin, D

    1991-01-01

    Despite great improvements over the past several years, the quality of demographic data in Africa is still a problem, and Africa remains the least well known continent. Population growth is extremely rapid, with all countries growing at annual rates of over 3%. The natural increase rate even shows some signs of increasing slightly in the next decade or so. Africa's population was estimated at 220 million in 1950, 650 million at present, and is projected at 1.5 billion by 2025. Africans represented 9% of the world population in 1960, but will increase to 19% around 2025. The rapid population growth is the result of declining mortality since the 1950s unmatched by changes in fertility. There are significant socioeconomic and rural-urban mortality differentials in Africa, but as yet only highly educated urbanites have measurably reduced their family size. 2 consequences of this rapid growth are the youth of the population, with almost 50% under 20 years, and its high density in some areas. By 2025, 18 countries will have densities of over 100 persons per sq km. Almost everywhere in Africa, family sizes are at least 6 children/woman. 3 factors explaining this high level of fertility are the earliness and universality of marriage, rates of contraceptive usage of only 4-10% in most countries, and declining durations of breast feeding and sexual abstinence, which traditionally served as brakes on fertility. As a rule, women marry young and remain married until the end of their reproductive years. Divorce and widowhood are common, but remarriage is usually rapid if the woman is still of reproductive age. Life expectancy at birth in sub-Saharan Africa has increased from some 36 years around 1950 to 50 years at present. Progress in control of mortality, and especially infant mortality, has been slower than expected, and Africa still has by far the lowest life expectancy of any major region. Regional, rural-urban, and socioeconomic mortality differentials are considerable and

  6. World Population: Fundamentals of Growth. Student Chartbook. Third Edition.

    Science.gov (United States)

    Kent, Mary Mederios

    This booklet is designed for K-12 students and educators to learn about world population growth factors. Data are shown through charts and graphs with brief explanations. The booklet contains: (1) "World Population Growth and Regional Distribution through History"; (2) "Population Growth through Natural Increase"; (3) "Effect of Migration on…

  7. Detecting differential growth of microbial populations with Gaussian process regression

    OpenAIRE

    Tonner, Peter D.; Darnell, Cynthia L.; Engelhardt, Barbara E.; Schmid, Amy K.

    2017-01-01

    Microbial growth curves are used to study differential effects of media, genetics, and stress on microbial population growth. Consequently, many modeling frameworks exist to capture microbial population growth measurements. However, current models are designed to quantify growth under conditions for which growth has a specific functional form. Extensions to these models are required to quantify the effects of perturbations, which often exhibit nonstandard growth curves. Rather than assume spe...

  8. Population Growth and Economic Development: Test for Causality

    OpenAIRE

    Khalid Mushtaq

    2006-01-01

    This paper examines the existenceof a long-run relationship between population and per capita income in Pakistan for the period 1960-2001 using cointegration analysis. Unit root results show that population is integrated of order zero while per capita income is integrated of order one; further, Johansen’s procedure showthat no long-run cointegrating relationship exists. Thus, population growth neither causes per capita income growth nor is caused by it. A corollary is that population growth n...

  9. Population Growth and Poverty in the Developing World.

    Science.gov (United States)

    Birdsall, Nancy

    1980-01-01

    The link between rapid population growth and the absolute poverty which currently afflicts 780 million people in developing countries (excluding China and other centrally planned economies) is examined. As a result of rapid population growth, many countries suffer slow per capita income growth, a lack of progress in reducing income inequality, and…

  10. Migration, urban population growth and regional disparity in China

    OpenAIRE

    Renard, Mary-Françoise; Xu, Zelai; Zhu, Nong

    2011-01-01

    The main objective of this paper is to study the determinants of city population growth in China during the 1990s', as well as the determinants of migrations towards cities, which constitutes the main source of urban population growth in this period. A second objective is to identify regional differences in the urban growth and migrations, that is, whether urban growth and migration patterns are different between coastal and inland provinces. Additionally, we are interested in the differences...

  11. The Population Growth and Carrying Capacity in Semarang City

    Science.gov (United States)

    Hariyanto; Hadi, Sudharto P.; Buchori, Imam

    2018-02-01

    Population growth and development of city activities take some lands to carry them. As a result, land use competition happens among persons, society or sector. Land necessity for settlement, industry, or sector has taken over farm land, therefore farm land has been converted intensively and massively. Chronologically, population growth will cause land necessity increase. Unproductive land, especially farm land will be converted. Furthermore, farm land conversion will cause carrying capacity change. Carrying capacity has certain bio capacity. With the population growth, it will increase resource consumption; on the other side, farm land conversion will decrease carrying capacity. The objective of the study is to know about the influence of population growth towards carrying capacity (bio capacity) in Semarang city. Land consumption per capita is indeed influenced by city population, the higher the population is, the lower the land consumption per capita. With the population growth, it will influence carrying capacity. Carrying capacity here is the ratio of area to population. Analytical descriptive method is applied in the study with all sub-districts in Semarang city as the analysis unit. Population here is sub-district area and population per sub-district in Semarang city. Population growth data period is from 2000 until 2015. Main variables of the study are area per sub-district, population, population growth, carrying capacity. Result of the study shows significant influence of carrying capacity decrease, especially some outskirts in Semarang city. This condition happens because the outskirts in Semarang city tend to have dense population growth. Range of carrying capacity in Semarang city is from 0,007 to 0,117 of 0 to 1. Almost all sub-districts in Semarang city show miserable condition, except Mijen and Tugu. The conclusion of the study is that population will decrease carrying capacity. Therefore, the government should control population growth by paying

  12. Dynamics of a Birth-Pulse Single-Species Model with Restricted Toxin Input and Pulse Harvesting

    Directory of Open Access Journals (Sweden)

    Yi Ma

    2010-01-01

    Full Text Available We consider a birth-pulses single-species model with restricted toxin input and pulse harvesting in a polluted environment. Pollution accumulates as a slowly decaying stock and is assumed to affect the growth of the renewable resource population. Firstly, by using the discrete dynamical system determined by the stroboscopic map, we obtain an exact 1-period solution of system whose birth function is Ricker function or Beverton-Holt function and obtain the threshold conditions for their stability. Furthermore, we show that the timing of harvesting has a strong impact on the maximum annual sustainable yield. The best timing of harvesting is immediately after the birth pulses. Finally, we investigate the effect of the amount of toxin input on the stable resource population size. We find that when the birth rate is comparatively lower, the population size is decreasing with the increase of toxin input; that when the birth rate is high, the population size may begin to rise and then drop with the increase of toxin input.

  13. Human Capital, Population Growth and Economic Development: Beyond Correlations

    OpenAIRE

    Rosenzweig, Mark R.

    1987-01-01

    Empirical evidence on three assertions commonly-made by population policy advocates about the relationships among population growth, human capital formation and economic development is discussed and evaluated in the light of economic-biological models of household behavior and of its relevance to population policy. The three assertions are that (a) population growth and human capital investments jointly reflect and respond to changes in the economic environment, (b) larger families directly i...

  14. Service employment and population growth in Japan.

    Science.gov (United States)

    Yabuta, J

    1981-01-01

    The relationship between activities in the service sector of the economy and urban growth is examined, with emphasis on how service activities are related to the pattern and speed of urban growth. The study is based on an analysis of 1970 Japanese census data for cities in the Chubu region that have more than 50,000 inhabitants.

  15. U.S. Population Growth: Prospects and Policy.

    Science.gov (United States)

    McFalls, Joseph A., Jr.; And Others

    1984-01-01

    The Commission on Population Growth and the American Future concluded that zero population growth (ZPG) is in the best interest of the United States. To achieve ZPG in the future, the United States must keep fertility and net immigration relatively low. Practical problems are discussed. (RM)

  16. Population growth of three freshwater prawns ( Macrobrachium spp ...

    African Journals Online (AJOL)

    Growth parameters of the populations of three freshwater prawns: Macrobrachium vollenhovenii, M. macrobrachion and M. felicinum in the Lower Ogun River were determined. For each population, lengthfrequency data for twenty-four month period (January 2006-December 2007) were analysed to determine the growth ...

  17. Beyond the Mean: Sensitivities of the Variance of Population Growth.

    Science.gov (United States)

    Trotter, Meredith V; Krishna-Kumar, Siddharth; Tuljapurkar, Shripad

    2013-03-01

    Populations in variable environments are described by both a mean growth rate and a variance of stochastic population growth. Increasing variance will increase the width of confidence bounds around estimates of population size, growth, probability of and time to quasi-extinction. However, traditional sensitivity analyses of stochastic matrix models only consider the sensitivity of the mean growth rate. We derive an exact method for calculating the sensitivity of the variance in population growth to changes in demographic parameters. Sensitivities of the variance also allow a new sensitivity calculation for the cumulative probability of quasi-extinction. We apply this new analysis tool to an empirical dataset on at-risk polar bears to demonstrate its utility in conservation biology We find that in many cases a change in life history parameters will increase both the mean and variance of population growth of polar bears. This counterintuitive behaviour of the variance complicates predictions about overall population impacts of management interventions. Sensitivity calculations for cumulative extinction risk factor in changes to both mean and variance, providing a highly useful quantitative tool for conservation management. The mean stochastic growth rate and its sensitivities do not fully describe the dynamics of population growth. The use of variance sensitivities gives a more complete understanding of population dynamics and facilitates the calculation of new sensitivities for extinction processes.

  18. Population growth and development: the case of Bangladesh.

    Science.gov (United States)

    Nakibullah, A

    1998-04-01

    In a poor, overly populated country such as Bangladesh, some believe that a high rate of population growth is a cause of poverty which impedes economic development. Population growth would therefore be exogenous to economic development. However, others believe that rapid population growth is a consequence rather than a cause of poverty. Population growth is therefore endogenous to economic development. Findings are presented from an investigation of whether population growth has been exogenous or endogenous with respect to Bangladesh's development process during the past 3 decades. The increase in per capita real gross domestic product (GDP) is used as a measure of development. Data on population, real GDP per capita, and real investment share of GDP are drawn from the Penn World Table prepared by Summers and Heston in 1991. The data are annual and cover the period 1959-90. Analysis of the data indicate that population growth is endogenous to Bangladesh's development process. These findings are reflected both in the Granger causality tests and the decompositions of variances of detrended real GDP per capita and population growth.

  19. Population, Productivity and Economic Growth Relations: the Case of Bulgaria

    Directory of Open Access Journals (Sweden)

    Venelin Terziev

    2017-12-01

    Full Text Available In this study the relationship between population, elderly population and economic growth is analyzed theoretically, taking into account the demographic change of the Bulgarian population and the more aging phenomenon. Thus, the change in the age structure of the Bulgarian population was investigated and the factors affecting the growth of the relationship between economic growth were investigated. In this study, attempts were made to determine the size of the changes taking place in the country's economy, depending on the livelihoods in Bulgaria.

  20. MODELING POPULATION GROWTH RATE IN RUSSIAN CITIES: SPATIAL ASPECTS

    Directory of Open Access Journals (Sweden)

    Olga S. Balash

    2013-01-01

    Full Text Available The article analyzes the growth rate of the urban population in Russia according to their size and region. It is revealed that the growth rate of the urban population are not the same for the regions of Russia. An econometric analysis of the data with geo-referenced using geographically weighted regression is conducted. In order to determine the causes of urban growth rate geographic market potential offered by Soo is used.

  1. The End of Population Growth in Asia

    OpenAIRE

    Lutz, W.; Scherbov, S.

    2002-01-01

    This paper presents probabilistic population projections for five regions of Asia (South Asia, Central Asia, China region, Pacific OECD and Pacific Asia) and Asia as a whole. Over this century, Asia will experience a very heterogeneous demographic development: Central Asia is still expected to almost double its population and South Asia will become by far the worlds most populous region, rapidly surpassing the China region. Simultaneously, todays Pacific OECD countries are likely to shrink in...

  2. Green sea turtle age, growth, population characteristics

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Morphology, sex ratio, body condition, disease status, age structure, and growth patterns were characterized for 448 green sea turtles cold stunned in St. Joseph...

  3. POPULATION GROWTH AND HEALTH CARE DELIVERY IN ...

    African Journals Online (AJOL)

    Adamawa state population is projected to be approximately 2,819million by the year 2001. This gives an increase of 716,784 as compared to the 1991 census figure, which is 2,102,053 for the state. The last census (1991) formed the basis of this projection. Further,1996 projected population was projected to the year 2001.

  4. Critical thresholds for eventual extinction in randomly disturbed population growth models.

    Science.gov (United States)

    Peckham, Scott D; Waymire, Edward C; De Leenheer, Patrick

    2018-02-16

    This paper considers several single species growth models featuring a carrying capacity, which are subject to random disturbances that lead to instantaneous population reduction at the disturbance times. This is motivated in part by growing concerns about the impacts of climate change. Our main goal is to understand whether or not the species can persist in the long run. We consider the discrete-time stochastic process obtained by sampling the system immediately after the disturbances, and find various thresholds for several modes of convergence of this discrete process, including thresholds for the absence or existence of a positively supported invariant distribution. These thresholds are given explicitly in terms of the intensity and frequency of the disturbances on the one hand, and the population's growth characteristics on the other. We also perform a similar threshold analysis for the original continuous-time stochastic process, and obtain a formula that allows us to express the invariant distribution for this continuous-time process in terms of the invariant distribution of the discrete-time process, and vice versa. Examples illustrate that these distributions can differ, and this sends a cautionary message to practitioners who wish to parameterize these and related models using field data. Our analysis relies heavily on a particular feature shared by all the deterministic growth models considered here, namely that their solutions exhibit an exponentially weighted averaging property between a function of the initial condition, and the same function applied to the carrying capacity. This property is due to the fact that these systems can be transformed into affine systems.

  5. The population growth and desertification crisis.

    Science.gov (United States)

    Milas, S

    1985-01-01

    Desertification is a result of overexploitation of the land through overcultivation, overgrazing, deforestation, and poor irrigation practices. This process is a result of the growing imbalance between population, resources, environment, and development. The principle problem causing desertification is not population increase per se; rather, it is due to mismanagement of the land. However, rapidly increasing population densities in the drylands of Africa, Asia, and Latin America have upset the former balance upon which subsistence agriculture depended, including long fallow periods to allow the land to regain its fertility. Arable land for the world as a whole is projected to decrease from its 1975 level of .31 ha/person to .15 ha/person by the year 2000. Population increases in the remaining croplands are expected to produce further encroachment on rangelands and forests and increased ecologic degradation, in turn producing further population pressure, poverty, land degradation, and desertification. The basic need is for better resource utilization. Halting desertification requires the restoration of the balance between man and land. Development, good resource management, and use of appropriate technologic advances are key factors. There is also a crucial need for each country to relate its population policy to its resource base and development plans. Population increase cannot continue indefinitely without regard for the realities of resources, development, and the environment.

  6. Soil science, population growth and food production: some historical developments

    NARCIS (Netherlands)

    Hartemink, A.E.

    2007-01-01

    The world¿s population has doubled since 1960. Currently, the developing world accounts for about 95% of the population growth with Africa as the world¿s fastest growing continent. The growing population has many implications but most of all it requires an increase in agricultural production to meet

  7. The demographic imperative: managing population growth

    NARCIS (Netherlands)

    A.M. Fischer (Andrew Martín)

    2010-01-01

    textabstractWith global population predicted to rise to over nine billion this century, can we find a solution to the problem of ever-increasing strains on resources without resorting to alarmism and xenophobia?

  8. Operculina from the northwestern Pacific (Sesoko Island, Japan) Species Differentiation, Population Dynamics, Growth and Development

    Science.gov (United States)

    Woeger, Julia; Eder, Wolfgang; Kinoshita, Shunichi; Briguglio, Antonino; Hohenegger, Johann

    2017-04-01

    During the last decades larger benthic foraminifera have gained importance as indicator species and are used in a variety of applications, from ecological monitoring, studying the effects of ocean acidification, or reconstructing paleoenvironments. They significantly contribute to the carbonate budget of costal areas and are invaluable tools in biostratigraphy. Even before their advancement as bioindicators, laboratory experiments have been conducted to investigate the effects of various ecological parameters on community composition, biology of single species, or investigating the effects of salinity and temperature on stable isotope composition of the foraminiferal test, to name only a few. The natural laboratory approach (continuous sampling over a period of more than one year) was conducted at the island of Sesoko (Okinawa, Japan). in combination with µ-CT scanning was used to reveal population dynamics of 3 different morphotypes of Operculina. The clarification of reproductive cycles as well as generation and size abundances were used to calculate natural growth models. Best fit was achieved using Bertalanffy and Michaelis-Menten functions. Exponential-, logistic-, generalized logistic-, Gompertz-function yielded weaker fits, when compared by coefficient of determination as well as Akaike Information criterion. The resulting growth curves and inferred growth rates were in turn used to evaluate the quality of a laboratory cultivation experiment carried out simultaneously over a period of 15 months. Culturing parameters such as temperature, light intensities, salinity and pH and light-dark duration were continuously adapted to measurements in the field. The average investigation time in culture was 77days. 13 Individuals lived more than 200 days, 3 reproduced asexually and one sexually. 14% of 186 Individuals were lost, while 22% could not be kept alive for more than one month. Growth curves also represent an instrumental source of information for the various

  9. [Population: evolution of Rwandan attitudes or the adaptation of the Rwanda population to population growth].

    Science.gov (United States)

    Ngendakumana, M

    1988-04-01

    A consequence of the increasing pressure on Rwanda's ecosystem resulting from population growth has been that demographic factors have played a significant role in modifying attitudes and beliefs of the population. The history of Rwanda demonstrates a constant struggle for survival in the face of increasing population pressure. Migration, colonization of new agricultural lands, adoption of new crops and new forms of animal husbandry have been responses to population pressures. Recent unprecedented population growth has exceeded the capacity of older systems of cultivation and combinations of agricultural and animal husbandry to support the population. Smaller animals have largely replaced the cattle that once roamed freely in extensive pastures, and new techniques of stabling animals, use of organic or chemical fertilizers, and new tools adapted to the shrinking size of farm plots have represented responses to the new demographic realities. The concept of the family is likewise undergoing modification in the face of population growth and modernization. Children, who once were valued as a source of labor and constrained to conform to the wishes of the parents in return for the eventual inheritance of the goods and livelihood, now increasingly look beyond the household for education and employment. Family land holdings have become too small to support all the members with a claim on them. The greater distances between family members inevitably mean that relations between them lose closeness. The choice of a marriage partner is increasingly assumed by the young people themselves and not by their families. Old traditions of food sharing and hospitality have been curtailed because of the increasing scarcity of food. Despite the changes engendered by increasing population pressure, pronatalist sentiments are still widespread. But the desire to assure the future of each child rather than to await his services, a new conception of women less dependent on their reproductive

  10. Population Growth and Local Home Environment Externality in an Endogenous Growth Model with Two Engines of Growth

    OpenAIRE

    Shirou Kuwahara; Katsunori Yamada

    2007-01-01

    This paper presents an endogenous growth model with population growth and an inter-generational spillover of human capital: we consider the ``local home environment externality conceptualized by Galor and Tsiddon (1997a). The model will generate a negative relationship between the population growth rate and the per capita GDP growth rate, which is also present in the data. Furthermore, multiple equilibrium paths will result. As far as we know, this is the first paper that derives a multiplici...

  11. Curbing population growth in Republic of Korea.

    Science.gov (United States)

    Woo-hyun, S

    1983-01-26

    The population of Korea is expected to increase by another 1/4 of the current population by the year 2000 if the government family planning program is successful. Aggravating Korea's demographic situation is the worldwide phenomenon of urban congestion. According to official statistics, Seoul's population increased from only 1 million in 1953 to 8.5 million in 1980, the latest year for which figures are available. While Seoul's population alone accounts for 22.3% of the total population, that of the greater Seoul area comprises 13,542,000 people or 35.5% of Korea's population. Most of the country's best institutions of higher learning are concentrated in Seoul, and in 1979 Seoul accounted for nearly half (47.7%) of the nation's college and graduate students. Seoul is also the center of the country's political, economic and cultural life and provides better employment opportunities than elsewhere in the country. The exodus of young people from rural areas and the growing census figures have triggered fears that the subsequently reduced agricultural productivity would result in a food supply crisis. In an attempt to remedy the demographic disparity between urban and rural areas, the government initiated a 10-year program in 1982 to promote jobs and improve medicare and the educational system in provincial cities. The plan encourages the establishment of factories and other auxiliary facilities outside the Seoul area that are necessary to support the 1988 Seoul Olympics. The program's success remains in question as it requires consistent, determined, and well coordinated efforts on the part of policy makers to curb the historical trend which has been gaining momentum over the past 100 years. 2 approaches have been adopted in the government's efforts to integrate population dynamics into the development process, overseas migration, and planned parenthood. Despite the 1981 liberalization of overseas travel for Koreans, Korean migration overseas is not expected to grow

  12. Population Aging and Economic Growth in Asia

    OpenAIRE

    David E. Bloom; David Canning; Jocelyn Finlay

    2008-01-01

    The decline in the total fertility rate between 1960 and 2005, coupled with an increase in life expectancy and the dynamic evolution of past variation in birth and death rates, is producing a significant shift in age structure in Asia. The age distribution has shifted from one with a high youth-age population share to one with a high old-age population share. We illustrate the role of these separate forces in shaping the age distribution. We also argue that the economic consequences of popula...

  13. Health, family planning and population growth.

    Science.gov (United States)

    Kessler, A; Standley, C C

    1973-01-01

    Maternal age over 35, close spacing of births, parity over 4, and unwanted pregnancy are discussed as factors that are associated with increased maternal and infant mortality. The likelihood of death due to childbearing is twice as high in the 30-40 age group as in the 20-30 age group and increases 4-to five-fold in the 40+ group. Brith Birth of less than 24-30 months are associated with a two-fold increase in neonatal and infant deaths. Health objectives of large scale family planning programs are geared toward avoiding such births. This paper proposes that these objectives would result in a decrease in maternal and child deaths and thereby lead to growth. A simultaneous lowering of birth rates, however, should offset this growth.

  14. Population, Pensions, and Endogenous Economic Growth

    OpenAIRE

    Heer, Burkhard; Irmen, Andreas

    2008-01-01

    We study the effect of a declining labor force on the incentives to engage in labor-saving technical change and ask how this effect is influenced by institutional characteristics of the pension scheme. When labor is scarcer it becomes more expensive and innovation investments that increase labor productivity are more profitable. We incorporate this channel in a new dynamic general equilibrium model with endogenous economic growth and heterogeneous overlapping generations. We calibrate the mod...

  15. Urban population and economic growth: South Asia perspective

    Directory of Open Access Journals (Sweden)

    Sandip Sarker

    2016-07-01

    Full Text Available Previously economic growth was generally discussed in terms of foreign direct investment (FDI, educational growth, savings, investments, inflation as well as trade openness of a nation. Very recently it has been identified that population is one of the major determinants of economic growth of a nation. In the recent years, the study of urbanization has gained a matter of concern in developing countries as it has been recognized as part of a larger process of economic development which is affecting developing countries. South Asian countries are one of the emerging economics and growing at a faster rate over the past few years. At the same time, population of South Asia is growing at a significant rate. Therefore the study has attempted to identify the causal relationship between urban population and economic growth in South Asia using a panel data analysis. The study makes use of the Augmented Dickey-Fuller (ADF and Phillips-Perron (PP, Pesaran as well as Fisher methods for panel unit root test. The panel Pedroni cointegration test suggests that there is long run relationship between the variables. The further panel Vector Error Correction Model (VECM suggests that there is long run causality running from urban population growth to economic growth in South Asia. The study concludes that the growth of urban population can have significant impact on economic growth in South Asia in the long run.

  16. Population Growth and Environmental Recovery: More People ...

    African Journals Online (AJOL)

    This paper surveys the impact of growing population pressure on the environmental resource base of Ethiopia at large, and that of West Gurageland in particular, as reflected in the land use/land cover changes in light of the two noted and widely held neo-Malthusian (pessimistic) and Boesrupian (optimistic) views.

  17. Poverty-led higher population growth in Bangladesh.

    Science.gov (United States)

    Nakibullah, A; Rahman, A

    1996-01-01

    This article discusses the issue whether population growth is exogenous or endogenous in the economic development of Bangladesh. Overpopulation adversely affects food supplies, foreign exchange, and human resources. Moreover, it depresses savings per capita and retards growth of physical capital per labor. Underdeveloped countries, like Bangladesh, are faced with the problem of allocating resources between infrastructure, education, and health service that are essential for human capital development and population control measures. With this, determination whether fertility is exogenous or endogenous is important for policy purposes in the context of Bangladesh. Results showed that there is a correlation between population growth and real gross domestic products per capita. Based on Granger causality test, population growth is endogenous in the development process of Bangladesh and its overpopulation is due to poverty. Thus, there is a need for appropriate policy to take measures to improve human capital and decrease fertility rates.

  18. Troublesome trends: population growth, distribution, migration.

    Science.gov (United States)

    1994-09-01

    The upcoming International Conference on Population and Development and its draft plan of action call for international cooperation in protecting and assisting refugees and displaced persons and in assuring positive consequences in host and origin countries. The draft plan also aims to protect the elderly through enhancing self-reliance and continued work and independent living in their own communities. Social support systems for the elderly must also be strengthened. The document is also concerned with the movement of population to cities and across borders. Recommendations on migration encourage governments to evaluate the impact of economic and environmental policies on population distribution and migration, to promote development of medium-sized urban centers, to encourage rural economic development and placement of industries in rural areas, and to support access to land ownership or use and access to water resources in rural areas. Rural infrastructure and social services need to be improved. Grassroots organizations and cooperatives for establishing credit and marketing products are emphasized. Weak local area management is an obstacle to socioeconomic development, environmental protection, and population distribution. Waste, water, and land management strategies should be adopted. Prevention of the root causes of displacement is particularly important when environmental damage is the consequence or the cause. Women, children, and the elderly who are displaced need protection. Refugee numbers have swelled from 8.5 million in 1985 to 19 million in 1993. Sudden and mass refugee arrivals should be afforded temporary protection until a solution can be found. Conditions must be created for safe and dignified, voluntary repatriation. The social and economic integration of documented, longterm migrants must be assured.

  19. The growth rates and population dynamics of bivalves in estuaries ...

    African Journals Online (AJOL)

    Studies on bivalves in the SwartkOps estuary have indicated that spatfall oa::an dlD'iDllate summer. After adult populations had been decimated by floods in 1971 spat IDII.de up a Iarp proportion of the bivalve population in 1973. Growth rata! vary at difl"erent intertidallevela and in difl"erent parts of the estuary and growth ...

  20. The Growth of Older Inmate Populations: How Population Aging Explains Rising Age at Admission.

    Science.gov (United States)

    Luallen, Jeremy; Cutler, Christopher

    2017-09-01

    Older inmates are the fastest growing segment of the prison population; however, the reasons for this are not well understood. One explanation is that the general population is aging, driving prison age distributions to change. For this article, we study the role of population aging in prison growth by investigating how the baby boom phenomenon of post-World War II has contributed to the growth of older inmate populations. We identify the impact of population aging using simulation methods that explain prison growth as the combination of criminal justice processes. Overall, we find evidence that population aging has played a significant role in explaining the growth of older inmate populations, in particular among inmates aged between 50 and 64 years, contributing to as much as half of the observed increase in these groups since 2000. This finding stands in contrast to the notion that population aging has little explanatory power in describing the growth of prison populations and implies that older inmate groups are more sensitive to compositional changes in the general population. We argue that prediction-based modeling of prison growth should more seriously consider the impacts and consequences of demographic shifts among older prisoner populations. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Population growth, economic security, and cultural change in wilderness counties

    Science.gov (United States)

    Paul A. Lorah

    2000-01-01

    A familiar version of the “jobs versus the environment” argument asserts that wilderness areas limit economic growth by locking up potentially productive natural resources. Analysis of the development paths of rural Western counties shows that this is unlikely: the presence of Wilderness is correlated with income, employment and population growth. Similarly, Wilderness...

  2. [Age structure and growth characteristic of Castanopsis fargesii population].

    Science.gov (United States)

    Song, Kun; Da, Liang-jun; Yang, Tong-hui; Yang, Xu-feng

    2007-02-01

    In this paper, the age structure and growth characteristics of Castanopsis fargesii population in a shade-tolerant broadleaved evergreen forest were studied, aimed to understand more about the regeneration patterns and dynamics of this population. The results showed that the age structure of C. fargesii population was of sporadic type, with two death peaks of a 30-year gap. This population had a good plasticity in growth to light condition. Because there were no significant differences in light condition under the canopy in vertical, the saplings came into their first suppression period when they were 5-8 years old, with a height growth rate less than 0. 1 m x a(-1) lasting for 10 years. The beginning time of the first growth suppression period was by the end of the first death peak of the population, and the ending time of the first growth suppression period was at the beginning of the second death peak of the population, demonstrating that growth characteristic was the key factor affecting the age structure of C. fargesii.

  3. Urban population and economic growth: South Asia perspective

    OpenAIRE

    Sandip Sarker; Arifuzzaman Khan; Mehdad Mamur Mannan

    2016-01-01

    Previously economic growth was generally discussed in terms of foreign direct investment (FDI), educational growth, savings, investments, inflation as well as trade openness of a nation. Very recently it has been identified that population is one of the major determinants of economic growth of a nation. In the recent years, the study of urbanization has gained a matter of concern in developing countries as it has been recognized as part of a larger process of economic development which is aff...

  4. Impact of Population Aging on Asia's Future Growth

    OpenAIRE

    Park, Donghyun; Shin, Kwanho

    2011-01-01

    First, the expert contributors argue, Asia must find ways to sustain rapid economic growth in the face of less favorable demographics, which implies slower growth of the workforce. Second, they contend, Asia must find ways to deliver affordable, adequate, and sustainable old-age economic security for its growing elderly population. Underpinned by rigorous analysis, a wide range of concrete policy options for sustaining economic growth while delivering economic security for the elderly are the...

  5. Bayesian modeling of bacterial growth for multiple populations

    OpenAIRE

    Palacios, Ana Paula; Marín, J. Miguel; Quinto, Emiliano J.; Wiper, Michael P.

    2014-01-01

    Bacterial growth models are commonly used for the prediction of microbial safety and the shelf life of perishable foods. Growth is affected by several environmental factors such as temperature, acidity level and salt concentration. In this study, we develop two models to describe bacterial growth for multiple populations under both equal and different environmental conditions. Firstly, a semi-parametric model based on the Gompertz equation is proposed. Assuming that the parameters of the Gomp...

  6. Bayesian modelling of bacterial growth for multiple populations

    OpenAIRE

    Palacios, Ana Paula; Marín Díazaraque, Juan Miguel; Quinto, Emiliano; Wiper, Michael Peter

    2012-01-01

    Bacterial growth models are commonly used for the prediction of microbial safety and the shelf life of perishable foods. Growth is affected by several environmental factors such as temperature, acidity level and salt concentration. In this study, we develop two models to describe bacterial growth for multiple populations under both equal and different environmental conditions. Firstly, a semi-parametric model based on the Gompertz equation is proposed. Assuming that the parameters of the Gomp...

  7. Implications of population growth for Nigeria's development | Fan ...

    African Journals Online (AJOL)

    The paper notes that high birth rate, low death rate and migration are the sources of the high population growth in Nigeria. The population then competes directly for the finite resources that could have been used to generate income. The consequences are dire: most Nigerian children are chronically malnourished as there ...

  8. Psychologists and the problem of population growth : Reply to Bridgeman

    NARCIS (Netherlands)

    Clayton, Susan; Carrico, Amanda; Steg, Linda; Swim, Janet K.; Bonnes, Mirilia; Devine-Wright, Patrick

    2017-01-01

    Bridgeman (2017) describes the important role of population growth in contributing to environmental problems. The present essay argues that population is an important component of human impact on the environment, but it must be considered in combination with consumption rates. A place-based

  9. Communication and The Challenges of Rapid Population Growth in ...

    African Journals Online (AJOL)

    The discourse also examined the various communication types in Africa and their appropriateness in educating Africans and their governments on the need to control high rate of population growth. Ironically, medical facilities available in African countries are grossly inadequate for the rapidly growing population.

  10. Analysis of Population Growth and Land Use in Pelaneng Bokong ...

    African Journals Online (AJOL)

    The question of whether population growth can contribute to environmental degradation and undermine efforts to manage resources sustainably and ultimately impairing agricultural development is a long-standing concern. This paper uses a three-tier methodology consisting of analysis of population dynamics, mapping of ...

  11. Metropolitan migration and population growth in selected developing countries.

    Science.gov (United States)

    1983-01-01

    The purpose of this article is to estimate the components of metropolitan population growth in selected developing countries during 1960-1970 period. The study examines population growth in 26 cities: 5 are in Africa, 8 in Asia, and 13 in Latin America, using data from national census publications. These cities in general are the political capitals of their countries, but some additional large cities were selected in Brazil, Mexico, and South Africa. All cities, at the beginning of the 1960-1970 decade had over 500,000 population; Accra, the only exception, reached this population level during the 1960s. Some cities had over 4 million residents in 1970. Net migration contributed about 37% to total metropolitan population growth; the remainder of the growth is attributable to natural increase. Migration has a much stronger impact on metropolitan growth than suggested by the above figure: 1) Several metropolitan areas, for various reasons, are unlikely to receive many migrants; without those cities, the share of metropolitan growth from net migration is 44%. 2) Estimates of the natural increase of migrants after their arrival in the metropolitan areas, when added to migration itself, changes the total contribution of migration to 49% in some metropolitan areas. 3) Even where net migration contributes a smaller proportion to metropolitan growth than natural increase, the rates of net migration are generally high and should be viewed in the context of rapid metropolitan population growth from natural increase alone. Finally, the paper also compares the components of metropolitan growth with the components of growth in the remaining urban areas. The results show that the metropolitan areas, in general, grow faster than the remaining urban areas, and that this more rapid growth is mostly due to a higher rate of net migration. Given the significance of migration for metropolitan growth, further investigations of the effects of these migration streams, particularly with

  12. Population dynamics of metastable growth-rate phenotypes.

    Directory of Open Access Journals (Sweden)

    Lindsay S Moore

    Full Text Available Neo-Darwinian evolution has presented a paradigm for population dynamics built on random mutations and selection with a clear separation of time-scales between single-cell mutation rates and the rate of reproduction. Laboratory experiments on evolving populations until now have concentrated on the fixation of beneficial mutations. Following the Darwinian paradigm, these experiments probed populations at low temporal resolution dictated by the rate of rare mutations, ignoring the intermediate evolving phenotypes. Selection however, works on phenotypes rather than genotypes. Research in recent years has uncovered the complexity of genotype-to-phenotype transformation and a wealth of intracellular processes including epigenetic inheritance, which operate on a wide range of time-scales. Here, by studying the adaptation dynamics of genetically rewired yeast cells, we show a novel type of population dynamics in which the intracellular processes intervene in shaping the population structure. Under constant environmental conditions, we measure a wide distribution of growth rates that coexist in the population for very long durations (>100 generations. Remarkably, the fastest growing cells do not take over the population on the time-scale dictated by the width of the growth-rate distributions and simple selection. Additionally, we measure significant fluctuations in the population distribution of various phenotypes: the fraction of exponentially-growing cells, the distributions of single-cell growth-rates and protein content. The observed fluctuations relax on time-scales of many generations and thus do not reflect noisy processes. Rather, our data show that the phenotypic state of the cells, including the growth-rate, for large populations in a constant environment is metastable and varies on time-scales that reflect the importance of long-term intracellular processes in shaping the population structure. This lack of time-scale separation between the

  13. Lebensraum: paradoxically, population growth may eventually end wars.

    Science.gov (United States)

    Simon, J L

    1989-03-01

    Population growth may progressively reduce 1 of the motives for making war. Namely, population growth threatens shortages of resources, and especially land. Impending shortages cause a search for ways to mitigate the shortages. The discoveries eventually produce greater availability of resources than if population growth and pressure on resources had never occurred. The argument runs as follows: 1) Rhetoric about resources scarcity induced by population density has often contributed to international conflict, even if economics has not been the main motive in making war. 2) In the pre-modern era, war to obtain land and other resources may sometimes have been an economically sound policy. 3) Politicians and others in industrially developed nations believe resources may still be a casus belli. 4) Land and other productive resources are no longer worth acquiring at the cost of war.

  14. Put an end to population growth and improve productivity.

    Science.gov (United States)

    Chung, U W

    1999-01-01

    The representative from Korea at the 15th Asian Parliamentarians' Meeting discussed issues concerning the environment, food security, and population growth. The implementation of population control programs is an issue that warrants continuous attention and efforts. The imbalance in the sexes, the decrease in the labor force, the rapid increase in number of senior citizens, insufficient food, unbalanced population distribution due to urbanization, and pollution are some of the new threats humanity faces. Like other developing countries, Korea put environmental protection on the back burner and its economic development took precedence over environmental concerns. As a result, Korea fostered industries that consume massive amounts of energy and resources, polluting the environment. Not only environmental hazards, but also social ills such as population concentration in urban areas, security problems, deteriorating living conditions, and crimes, developed due to industrialization and urbanization. The main priority should be the revival of the earth and the study of the effects of population growth on the environment. The root causes of environmental destruction consist of explosive population growth, industrial pollution, and development; the best way to restrain these destructive forces is to put an end to population growth. To improve food security, humanity needs to make specific action plans to implement the Hague Declaration urging the establishment of the World Food Bank.

  15. Understanding population growth in the peri-urban region.

    Science.gov (United States)

    Ford, T

    1999-01-01

    This article advocates a new approach to understanding periurban population growth. A conceptual model is developed that identifies four distinct growth processes: suburbanization, counterurbanization, population retention, and centripetal migration. Each of these growth processes acts differently on particular population subgroups. The differences are reflected in variations in the spatial manifestation of periurban growth within Australia. Suburbanization process is differentiated from counterurbanization by employing three indicators of suburbanization. The first indicator includes the broad situation of the periurban destination and is defined as in-migration from the metropolitan area to adjacent, accessible periurban locations. The second indicator lies in the assessment of the commuting and social linkages with the metropolitan maintained by migrants. The third indicator is the nature of the migrants' residential destination site. Counterurbanization is largely seen to be a shift in population down the urban hierarchy to smaller centers and localities beyond the existing metropolitan boundaries. Furthermore, the article discusses the four indicators that distinguish counterurbanization from suburbanization. Another important process contributing to periurban growth is population retention. Two key indicators that lie in the measurement of increased period of residence and reduced rates of out-migration overtime characterize this process.

  16. Are Ascaris lumbricoides and Ascaris suum a single species?

    Science.gov (United States)

    Leles, Daniela; Gardner, Scott L; Reinhard, Karl; Iñiguez, Alena; Araujo, Adauto

    2012-02-20

    Since the original description and naming of Ascaris lumbricoides from humans by Linnaeus in 1758 and later of Ascaris suum from pigs by Goeze 1782, these species have been considered to be valid. Four hypotheses relative to the conspecificity or lack thereof (and thus origin of these species) are possible: 1) Ascaris lumbricoides (usually infecting humans) and Ascaris suum (recorded mostly from pigs) are both valid species, with the two species originating via a speciation event from a common ancestor sometime before the domestication of pigs by humans, or 2) Ascaris lumbricoides in humans is derived directly from the species A. suum found in pigs with A. suum then existing as a persistent ancestor after formation of A. lumbricoides, or 3) Ascaris suum is derived directly from A. lumbricoides with the persistent ancestor being A. lumbricoides and A. suum being the newly derived species, and finally, 4) Ascaris lumbricoides and A. suum are the same species, this hypothesis being supported by studies showing both low morphological and low genetic divergence at several genes. We present and discuss paleoparasitological and genetic evidence that complement new data to evaluate the origin and evolution of Ascaris spp. in humans and pigs, and the uniqueness of the species in both hosts. Finally, we conclude that Ascaris lumbricoides and A. suum are a single species and that the name A. lumbricoides Linnaeus 1758 has taxonomic priority; therefore A. suum Goeze 1782 should be considered a synonym of A. lumbricoides.

  17. Modeling bacterial population growth from stochastic single-cell dynamics.

    Science.gov (United States)

    Alonso, Antonio A; Molina, Ignacio; Theodoropoulos, Constantinos

    2014-09-01

    A few bacterial cells may be sufficient to produce a food-borne illness outbreak, provided that they are capable of adapting and proliferating on a food matrix. This is why any quantitative health risk assessment policy must incorporate methods to accurately predict the growth of bacterial populations from a small number of pathogens. In this aim, mathematical models have become a powerful tool. Unfortunately, at low cell concentrations, standard deterministic models fail to predict the fate of the population, essentially because the heterogeneity between individuals becomes relevant. In this work, a stochastic differential equation (SDE) model is proposed to describe variability within single-cell growth and division and to simulate population growth from a given initial number of individuals. We provide evidence of the model ability to explain the observed distributions of times to division, including the lag time produced by the adaptation to the environment, by comparing model predictions with experiments from the literature for Escherichia coli, Listeria innocua, and Salmonella enterica. The model is shown to accurately predict experimental growth population dynamics for both small and large microbial populations. The use of stochastic models for the estimation of parameters to successfully fit experimental data is a particularly challenging problem. For instance, if Monte Carlo methods are employed to model the required distributions of times to division, the parameter estimation problem can become numerically intractable. We overcame this limitation by converting the stochastic description to a partial differential equation (backward Kolmogorov) instead, which relates to the distribution of division times. Contrary to previous stochastic formulations based on random parameters, the present model is capable of explaining the variability observed in populations that result from the growth of a small number of initial cells as well as the lack of it compared to

  18. Population growth, human development, and deforestation in biodiversity hotspots.

    Science.gov (United States)

    Jha, S; Bawa, K S

    2006-06-01

    Human population and development activities affect the rate of deforestation in biodiversity hotspots. We quantified the effect of human population growth and development on rates of deforestation and analyzed the relationship between these causal factors in the 1980s and 1990s. We compared the averages of population growth, human development index (HDI, which measures income, health, and education), and deforestation rate and computed correlations among these variables for countries that contain biodiversity hotspots. When population growth was high and HDI was low there was a high rate of deforestation, but when HDI was high, rate of deforestation was low, despite high population growth. The correlation among variables was significant for the 1990s but not for the 1980s. The relationship between population growth and HDI had a regional pattern that reflected the historical process of development. Based on the changes in HDI and deforestation rate over time, we identified two drivers of deforestation: policy choice and human-development constraints. Policy choices that disregard conservation may cause the loss of forests even in countries that are relatively developed. Lack of development in other countries, on the other hand, may increase the pressure on forests to meet the basic needs of the human population. Deforestation resulting from policy choices may be easier to fix than deforestation arising from human development constraints. To prevent deforestation in the countries that have such constraints, transfer of material and intellectual resources from developed countries may be needed. Popular interest in sustainable development in developed countries can facilitate the transfer of these resources.

  19. The Strategies, Complexities, and Realities of Zero Prison Population Growth

    Directory of Open Access Journals (Sweden)

    Evelyn J. Patterson

    2017-06-01

    Full Text Available Although there is general consensus that growth in the prison population should be reversed, there is little agreement on how to achieve this goal. In this paper, I apply classic demographic methods to answer questions that assess the strategies, complexities, and realities of routes to zero and negative prison population growth. Modified admissions policies have had the greatest impact on halting growth, whereas decreasing the length of sentences has had only a modest, short-term influence on the prison population size. As state and federal policy-makers consider reducing sentences for selective classes of nonviolent offenders, it is important that they have a holistic understanding of the implications of such policies. Traditionally, this type of modification has been coupled with more punitive policies for violent offenders, a pattern that reinforces the appearance of having “tough on crime” policies. Model estimates show that such strategies countervail the overall goal of decreasing the size of the prison population. Regardless of underlying reasons to halt growth of the prison populations, integration of the formal demography enable a means to assess the short- and long-term consequences of current and future policy.

  20. Inflation, GDP growth and population change in the USA

    OpenAIRE

    Ivan Kitov

    2005-01-01

    Inflation in the USA between 1960 and 2004 is studied in the framework of the revealed rigidity of the personal income distribution normalized to the total nominal GDP. Inflation is found to be a mechanism, which prevents changes in the relative incomes induced by economic growth and population changes - both in number and age structure. A model is developed linking CPI to GDP growth rate and relative change of the number of people of some specific age. The GDP growth rate is characterized by...

  1. A model of northern pintail productivity and population growth rate

    Science.gov (United States)

    Flint, Paul L.; Grand, James B.; Rockwell, Robert F.

    1998-01-01

    Our objective was to synthesize individual components of reproductive ecology into a single estimate of productivity and to assess the relative effects of survival and productivity on population dynamics. We used information on nesting ecology, renesting potential, and duckling survival of northern pintails (Anas acuta) collected on the Yukon-Kuskokwim Delta (Y-K Delta), Alaska, 1991-95, to model the number of ducklings produced under a range of nest success and duckling survival probabilities. Using average values of 25% nest success, 11% duckling survival, and 56% renesting probability from our study population, we calculated that all young in our population were produced by 13% of the breeding females, and that early-nesting females produced more young than later-nesting females. Further, we calculated, on average, that each female produced only 0.16 young females/nesting season. We combined these results with estimates of first-year and adult survival to examine the growth rate (X) of the population and the relative contributions of these demographic parameters to that growth rate. Contrary to aerial survey data, the population projection model suggests our study population is declining rapidly (X = 0.6969). The relative effects on population growth rate were 0.1175 for reproductive success, 0.1175 for first-year survival, and 0.8825 for adult survival. Adult survival had the greatest influence on X for our population, and this conclusion was robust over a range of survival and productivity estimates. Given published estimates of annual survival for adult females (61%), our model suggested nest success and duckling survival need to increase to approximately 40% to achieve population stability. We discuss reasons for the apparent discrepancy in population trends between our model and aerial surveys in terms of bias in productivity and survival estimates.

  2. Urban Ecology: Patterns of Population Growth and Ecological Effects

    Science.gov (United States)

    Wayne C. Zipperer; Steward T.A. Pickett

    2012-01-01

    Currently, over 50% of the world’s population lives in urban areas. By 2050, this estimate is expected to be 70%. This urban growth, however, is not uniformly distributed around the world. The majority of it will occur in developing nations and create megacities whose populations exceed at least 10 million people. Not all urban areas, however, are growing. Some are...

  3. [On the relationship between population growth and economic development].

    Science.gov (United States)

    Xu, D

    1983-03-29

    People are producers as well as consumers. If we look at only one side and ignore the other, we will be unable to reach impartial conclusions concerning the population problem. An obvious and close relationship exists between population growth and national economic development. If the two do not match each other, there will be numerous contradictory problems. For example, if the population grows too fast, serious social and economic problems will be created, such as a rise in the demand for living resources, an oversupply of the labor force, unemployment, and an insufficient availability of arable land, a shortage of public housing, more demand for health care and public transportation, and cultural and educational enterprises. In addition, a rapid population growth may cause more problems for the natural environment. As a result of overpopulation, the pressure on natural resources will be intensified and may therefore cause damage to the environment and create an ecological imbalance. All the above may bring very serious difficulties and obstacles to the advancement of socialism and modernized constructions. To avoid this, we must try to solve the population problem thoroughly and maintain a balanced relationship between the population growth and economic development.

  4. 1 2 POPULATION GROWTH AND THE DILEMMA OF RURAL LIFE ...

    African Journals Online (AJOL)

    Dr Ike

    beleaguered state of these rural communities and the national economy. Specifically, the causes of ... markets go waste, thus marginalizing their income from farm proceeds over the years. Another common feature of rural .... the migration of foreigners into the country, account for the accelerated population growth rate in the ...

  5. 1 2 POPULATION GROWTH AND THE DILEMMA OF RURAL LIFE ...

    African Journals Online (AJOL)

    Dr Ike

    In this paper, efforts are made to discuss the issue of population growth in Nigeria in its various ramifications. ... the rural environment are said to be depression, degradation and deprivation4. In most rural areas in Nigeria, ... plight of many rural parents, the latter cannot afford to give educational opportunities to their children ...

  6. Poverty, population growth, and youth violence in DRC's cities ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2016-04-28

    Apr 28, 2016 ... Results from IDRC-supported research at the Université de Kinshasa, Democratic Republic of Congo (DRC), show that unregulated population growth — averaging 10 births per woman — combined with a lack of education and economic opportunities for impoverished youth, contribute to the proliferation ...

  7. The relationship between population growth and poverty in Africa: a ...

    African Journals Online (AJOL)

    The mainstream view from these debates and discussions is that rapid population growth in Africa has put pressure on the environment, leading to environmental degradation which translates into shortfall in food production and atrophied development. This view is as a result of ritualistic adherence to narrow ideological ...

  8. The Vatican & Population Growth Control: Why an American Confrontation?

    Science.gov (United States)

    Mumford, Stephen D.

    1983-01-01

    The Vatican, because of its position on population growth, threatens the security of all nations. Catholic countries with right-wing dictatorships cannot confront the Vatican on family planning and survive. U.S. Catholics must confront the Vatican on this issue. American lay Catholics must break the American church away from the Vatican control.…

  9. Population Growth, Hysteresis and Development Outcomes in Sub ...

    African Journals Online (AJOL)

    The technique of analysis is the Auto-Regressive Distributed Lag (ARDL) Bound test for long-run impacts and equilibrium conditions while we re-parametised the model for short-run impact analyses. We found evidence for hysteretic unemployment in Nigeria and that population growth does not play a role in the persistence ...

  10. Poverty, population growth, and youth violence in DRC's cities ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    21 avr. 2016 ... Results from IDRC-supported research at the Université de Kinshasa, Democratic Republic of Congo (DRC), show that unregulated population growth — averaging 10 births per woman — combined with a lack of education and economic opportunities for impoverished youth, contribute to the proliferation ...

  11. 525 Population Growth, Hysteresis and Development Outcomes in ...

    African Journals Online (AJOL)

    a refinement of the Malthusian theory which, holds an extreme position and presupposes that the world population ... economy; a concept known as jobless growth (see Tella and Ayinde, 2015) could mean that unemployment has .... effect of social infrastructure. Given only demographic uncertainty, they found a 95 percent ...

  12. Population and prehistory I: Food-dependent population growth in constant environments.

    Science.gov (United States)

    Lee, Charlotte T; Tuljapurkar, Shripad

    2008-06-01

    We present a demographic model that describes the feedbacks between food supply, human mortality and fertility rates, and labor availability in expanding populations, where arable land area is not limiting. This model provides a quantitative framework to describe how environment, technology, and culture interact to influence the fates of preindustrial agricultural populations. We present equilibrium conditions and derive approximations for the equilibrium population growth rate, food availability, and other food-dependent measures of population well-being. We examine how the approximations respond to environmental changes and to human choices, and find that the impact of environmental quality depends upon whether it manifests through agricultural yield or maximum (food-independent) survival rates. Human choices can complement or offset environmental effects: greater labor investments increase both population growth and well-being, and therefore can counteract lower agricultural yield, while fertility control decreases the growth rate but can increase or decrease well-being. Finally we establish equilibrium stability criteria, and argue that the potential for loss of local stability at low population growth rates could have important consequences for populations that suffer significant environmental or demographic shocks.

  13. Impact of population growth and population ethics on climate change mitigation policy.

    Science.gov (United States)

    Scovronick, Noah; Budolfson, Mark B; Dennig, Francis; Fleurbaey, Marc; Siebert, Asher; Socolow, Robert H; Spears, Dean; Wagner, Fabian

    2017-11-14

    Future population growth is uncertain and matters for climate policy: higher growth entails more emissions and means more people will be vulnerable to climate-related impacts. We show that how future population is valued importantly determines mitigation decisions. Using the Dynamic Integrated Climate-Economy model, we explore two approaches to valuing population: a discounted version of total utilitarianism (TU), which considers total wellbeing and is standard in social cost of carbon dioxide (SCC) models, and of average utilitarianism (AU), which ignores population size and sums only each time period's discounted average wellbeing. Under both approaches, as population increases the SCC increases, but optimal peak temperature decreases. The effect is larger under TU, because it responds to the fact that a larger population means climate change hurts more people: for example, in 2025, assuming the United Nations (UN)-high rather than UN-low population scenario entails an increase in the SCC of 85% under TU vs. 5% under AU. The difference in the SCC between the two population scenarios under TU is comparable to commonly debated decisions regarding time discounting. Additionally, we estimate the avoided mitigation costs implied by plausible reductions in population growth, finding that large near-term savings ($billions annually) occur under TU; savings under AU emerge in the more distant future. These savings are larger than spending shortfalls for human development policies that may lower fertility. Finally, we show that whether lowering population growth entails overall improvements in wellbeing-rather than merely cost savings-again depends on the ethical approach to valuing population. Copyright © 2017 the Author(s). Published by PNAS.

  14. Population growth is a variable open to change

    Science.gov (United States)

    Potts, M.

    2016-12-01

    The absolute number of people and the rate of population growth have an impact on climate mitigation, adaptation and possible conflict. Half the pregnancies in the US are unintended. Robust quantitative evidence from California demonstrates that improving access to family planning is the single most cost-effective way of mitigating our carbon footprint. Globally, there are 80 million unintended pregnancies annually. Many non-evidence barriers deprive women of the information and means required to separate sex from childbearing. Between 1960 and 1990, meeting the need for family planning led to a rapid fall in family size in much of Asia. Since 1990, funding for family planning has collapsed and fertility decline has stalled. The UN projects that by 2100 global population will increase by 3.8 billion (equal to world population in 1975). 80% of this growth will be in Africa. Studies project that climate change will undermine crop yields in parts of Africa, especially the Sahel. A high ratio of young males to the rest of the population is a risk factor in conflict. Today, only 1% of overseas assistance is allocated to family planning. Based on analysis of the past, doubling that investment would accelerate fertility decline, facilitating climate mitigation and adaptation, and possibly reducing conflict. Population and family planning were pushed off the international agenda by unacceptably and tragic episodes of coercion in China and India. However, there is compelling data that when voluntary family planning is widely available then family size can fall rapidly, as occurred in the Islamic Republic of Iran, where fertility fell more rapidly than in any other country in history. Family planning is listening to what women want not telling people want to do. Population growth is a variable open to change in a human rights framework. Population and family planning are variables relevant to the scientific agenda of the AGU.

  15. Population growth and food supply in sub-Saharan Africa.

    Science.gov (United States)

    Meerman, J; Cochrane, S H

    1982-09-01

    It is argued in this article that sub-Saharan Africa, given its present institutions and endowments of capital and technology, is already dangerously close to overpopulation. The rapid growth of its population projected for the next decades will greatly increase human misery and depress economic development. Specifically, rapid population growth will have disastrous effects on the region's ability to increase exports and provide people with food. There must be a search for new ways in which these effects could be mitigated. In sub-Saharan Africa fertility either continues to be very high or is increasing, in part due to some decline in traditional practices that reduce fertility, such as prolonged breastfeeding. This situation and the expectation of declining mortality imply that African population growth may increase further. Currently, population in sub-Saharan Africa is about half that of India and a third of China. There are 2 main reasons why reduced fertility in the next few decades is unlikely in sub-Saharan Africa as a whole: Africa has low literacy, high infant and child mortality, and low urbanization; and average African fertility rates may even increase for the next 20 years or so. The question that arises is what are the implications of continuing and rapid population growth for the African food supply. The region's cereal production is largely restricted to 4 grains, i.e., millet, sorghum, maize, and rice. The volume of grain production is less, by weight, than 60% of the production of roots and tubers. There are 2 main differences between the output of these crops in sub-Saharan Africa and the rest of the world: yields/hectare are lower in Africa than in elsewhere; and yields have generally been decreasing or largely constant in Africa. The low productivity has several causes. Today, population pressure has brought diminishing returns to traditional agriculture in much of the Sahel and the savanna, in parts of East Africa, Southern Africa, and parts

  16. Population growth to put pressure on some food supplies.

    Science.gov (United States)

    1997-01-01

    Continued high population growth in developing countries is likely to lead to intense pressure to produce more rice, according to estimates from the Manila-based International Rice Research Institute (IRRI). Ms. Mercedita Sombilla, a research scientist with IRRI, said that the projected increase in Asia's population will be the major force in accelerating demand for rice. According to various issues of the ESCAP Population Data Sheet, the population of the region will have increased from 3.3 billion in 1995 to almost 4.6 billion in 2020. The greatest growth in demand is expected to come from the lower-income countries of Asia, such as Bangladesh, India, Myanmar, Philippines, and Viet Nam, she said. However, in terms of overall food supplies, the Organization for Economic Cooperation and Development (OECD) estimates that food supplies will be sufficient. "Expecting reasonably strong productivity growth to be sustainable, no global food crisis seems likely to occur" between now and 2020, the organization stated in its report entitled "The World in 2020: Towards a New Global Age". full text

  17. Adapting to Population Growth: The Evolutionary Alternative to Malthus

    Directory of Open Access Journals (Sweden)

    Axel Kristinsson

    2016-06-01

    Full Text Available A long-standing debate on the dynamics of population growth in human history has become polarized between a Malthusian stance and a Boserupian one. The former tends to view population growth as limited by carrying capacity, dependent on environment and technology, whereas the latter sees population growth itself as a major inducement to social, economic and technological developments. In this paper the authors experiment with approaching this debate by using recent developments in evolutionary theory. According to these, evolutionary principles, as expounded by Charles Darwin and subsequent evolutionary scientists, apply not only to biological evolution but also to social or cultural evolution. Here, the role of genes is taken over by culture and, since culture is much more pliable than our DNA, evolution speeds up. As the only organisms on Earth whose evolution relies as heavily on culture as on genes, humans have become extremely adaptable. Their hyper-adaptability suggest that humans, through their cultural evolution, have managed increasingly to adapt to their own growing population, thus succeeding in accommodating ever-growing numbers. This hypothesis fits the Boserupian approach to population very well but less so the Malthusian one, perhaps indicating a gradual shift from a Malthusian regime to a Boserupian one in human history. The hypothesis is discussed and examined through four case studies: The beginning of farming around Göbekli Tepe in southeast Turkey, the productive farming systems of Tiwanaku in South America, the population crisis of late medieval and early modern Iceland, and the ‘collapse’ of Rapa Nui (Easter Island.

  18. Population growth, accessibility spillovers and persistent borders: Historical growth in West-European municipalities.

    Science.gov (United States)

    Jacobs-Crisioni, Chris; Koomen, Eric

    2017-06-01

    Lack of cross-border transport supply has repeatedly been blamed for the fact that national borders limit spatial interaction and, consequently, the growth of border regions. This study applies an accessibility approach to investigate for most municipalities in ten countries in mainland West Europe if foreign transport supply is lagging behind, and if population growth in these municipalities has been affected by the limits that national borders have imposed on market access. To do so, data describing historical population changes and road networks between 1961 and 2011 have been used. The results show that in the study area, cross-border transport accessibility was not at a disadvantage in 1961 and has since then grown even more than domestic accessibility. However, municipal population growth has depended almost exclusively on domestic market access. Processes of economic international integration in the study area are found to coincide with the growth of cross-border accessibility, but do not have a clear coincidence with the effects of cross-border accessibility on population growth.

  19. What is Growth? Concurrent determination of a bacterial population's many shades of growth

    Science.gov (United States)

    Lambert, Guillaume; Kussell, Edo

    2013-03-01

    One of the most exciting developments in the study of the physics of microbial life is the ability to precisely monitor stochastic variations of gene expression in individual cells. A fundamental question is whether these variations improve the long-term ability of a population to adapt to new environments. While variations in gene expression in bacteria are easily measured through the use of reporter systems such as green fluorescent proteins and its variants, precise determination of a cell's growth rate, and how it is influenced by its immediate environment, remains challenging. Here, we show that many conflicting and ambiguous definitions of bacterial growth can actually be used interchangeably in E. coli. Indeed, by monitoring small populations of E. coli bacteria inside a microfluidic device, we show that seemingly independent measurements of growth (elongation rate and the average division time, for instance) agree very precisely with one another. We combine these definitions with the population's length and age distribution to very precisely quantify the influence of temperature variations on a population's growth rate. We conclude by using coalescence theory to describe the evolution of a population's genetic structure over time.

  20. Cellular automata for population growth prediction: Tripoli-Libya case

    OpenAIRE

    Zidan, Adel

    2015-01-01

    This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London Due to obstruction in the national plan of urbanization in Tripoli (Libya) and population growth, serious problems have emerged in the form of random settlements, overcrowding and poor infrastructure. After more than two decades of inertia, the government has created a national plan in order to resolve the problems, hence it has enforced the demolition of some zones and modified othe...

  1. Rapid population growth and environmental degradation: ultimate versus proximate factors.

    Science.gov (United States)

    Shaw, R P

    1989-01-01

    This philosophical review of 2 arguments about responsibility for and solutions to environmental degradation concludes that both sides are correct: the ultimate and the proximal causes. Ultimate causes of pollution are defined as the technology responsible for a given type of pollution, such as burning fossil fuel; proximate causes are defined as situation-specific factors confounding the problem, such as population density or rate of growth. Commoner and others argue that developed countries with low or negative population growth rates are responsible for 80% of world pollution, primarily in polluting technologies such as automobiles, power generation, plastics, pesticides, toxic wastes, garbage, warfaring, and nuclear weapons wastes. Distortionary policies also contribute; examples are agricultural trade protection, land mismanagement, urban bias in expenditures, and institutional rigidity., Poor nations are responsible for very little pollution because poverty allows little waste or expenditures for polluting, synthetic technologies. The proximal causes of pollution include numbers and rate of growth of populations responsible for the pollution. Since change in the ultimate cause of pollution remains out of reach, altering the numbers of polluters can make a difference. Predictions are made for proportions of the world's total waste production, assuming current 1.6 tons/capita for developed countries and 0.17 tons/capita for developing countries. If developing countries grow at current rates and become more wealthy, they will be emitting half the world's waste by 2025. ON the other hand, unsustainable population growth goes along with inadequate investment in human capital: education, health, employment, infrastructure. The solution is to improve farming technologies in the 117 non-self-sufficient countries, fund development in the most unsustainable enclaves of growing countries, break institutionalized socio-political rigidity in these enclaves, and focus on

  2. Is faster economic growth compatible with reductions in carbon emissions? The role of diminished population growth

    Science.gov (United States)

    Casey, Gregory; Galor, Oded

    2017-01-01

    We provide evidence that lower fertility can simultaneously increase income per capita and lower carbon emissions, eliminating a trade-off central to most policies aimed at slowing global climate change. We estimate the effect of lower fertility on carbon emissions, accounting for the fact that changes in fertility patterns affect carbon emissions through three channels: total population, the age structure of the population, and economic output. Our analysis proceeds in two steps. First, we estimate the elasticity of carbon emissions with respect to population and income per capita in an unbalanced yearly panel of cross-country data from 1950-2010. We demonstrate that the elasticity with respect to population is nearly seven times larger than the elasticity with respect to income per capita and that this difference is statistically significant. Thus, the regression results imply that 1% slower population growth could be accompanied by an increase in income per capita of nearly 7% while still lowering carbon emissions. In the second part of our analysis, we use a recently constructed economic-demographic model of Nigeria to estimate the effect of lower fertility on carbon emissions, accounting for the impacts of fertility on population growth, population age structure, and income per capita. We find that by 2100 C.E. moving from the medium to the low variant of the UN fertility projection leads to 35% lower yearly emissions and 15% higher income per capita. These results suggest that population policies could be part of the approach to combating global climate change.

  3. Population, internal migration, and economic growth: an empirical analysis.

    Science.gov (United States)

    Moreland, R S

    1982-01-01

    The role of population growth in the development process has received increasing attention during the last 15 years, as manifested in the literature in 3 broad categories. In the 1st category, the effects of rapid population growth on the growth of income have been studied with the use of simulation models, which sometimes include endogenous population growth. The 2nd category of the literature is concerned with theoretical and empirical studies of the economic determinants of various demographic rates--most usually fertility. Internal migration and dualism is the 3rd population development category to recieve attention. An attempt is made to synthesize developments in these 3 categories by estimating from a consistent set of data a 2 sector economic demographic model in which the major demographic rates are endogenous. Due to the fact that the interactions between economic and demographic variables are nonlinear and complex, the indirect effects of changes in a particular variable may depend upon the balance of numerical coefficients. For this reason it was felt that the model should be empirically grounded. A brief overview of the model is provided, and the model is compared to some similar existing models. Estimation of the model's 9 behavior equations is discussed, followed by a "base run" simulation of a developing country "stereotype" and a report of a number of policy experiments. The relatively new field of economic determinants of demographic variables was drawn upon in estimating equations to endogenize demographic phenomena that are frequently left exogenous in simulation models. The fertility and labor force participation rate functions are fairly standard, but a step beyong existing literature was taken in the life expectancy and intersectorial migration equations. On the economic side, sectoral savings functions were estimated, and it was found that the marginal propensity to save is lower in agriculture than in nonagriculture. Testing to see the

  4. Apocalypse when? Population growth and food supply in South Asia.

    Science.gov (United States)

    Greenspan, A

    1994-12-01

    Food demands for staple grains are expected to almost double over the next 25 years in South Asia, due to population growth and increased standards of living. Trends in the mid-1990s suggest that neither pessimism nor optimism prevails in the region. There is wide diversity among and within countries. Trends suggest that population densities are already the highest in the world, and the amount of arable land is declining. Urban growth has moved onto farm land and farmers have been pushed onto more marginal lands or have become landless. Land intensification has produced mixed results. Cereal production per capita has increased since the 1950s in India, with about 75% of the region's population, but Pakistan's increases were not sustained into the 1980s. Average daily caloric intake per person in the region of 2214 is below the level in Sub-Saharan Africa. In Bangladesh, levels are particularly worrisome at 2037. The environmental impact has not been easily quantified, but experts have suggested that pressure on farm land has contributed to loss of soil fertility and water resource loss. Further intensification of farming is feasible, but difficult and more expensive than in the past. Regardless of production problems and solutions, there is also the very real problem of poor food distribution and lack of purchasing power. Farm management skills must be utilized, if environmental degradation is to be avoided. There is the added unknown of what climate changes will occur and how agricultural production will be affected. The policy implications are that increased food production must be made a political priority. Policies must support agricultural research into improved technologies and support distribution of technological advances to a wider number of farmers. Rural infrastructures such as roads, market outlets, and credit agencies must be established. Policies must be removed that disadvantage farmers, such as inappropriate subsidies for irrigation water

  5. Growth of rural population in Punjab, 1971-81.

    Science.gov (United States)

    Gill, M S

    1987-01-01

    Except for the decade 1941-1951, in which Punjab's population declined because of a huge exchange of population between India and Pakistan and a large loss of life, the decade 1971-1981 was the 1st decade since 1911 to experience a deceleration in the growth rate of the rural population of Punjab, India. The deceleration was due to out-migration to urban areas. The scheduled caste population increased 28.37% between 1971 and 1981, while the nonscheduled caste population increased by only 13.32%, which was considerably below the rate of natural increase. Nonscheduled castes had experienced substantial out-migration because of 1) improved transport and communication facilities which enabled them to move to urban centers; 2) mechanization of main farming operations and easy availability of migrant laborers which lessened the need for family labor; 3) the rise of a relatively mobile younger generation with a high literacy rate; 4) rapidly decreasing land holdings which strengthened the push factor in the countryside; and 5) rising aspirations, especially among the younger generation. In 1981, Sikhs constituted 71.3% of the rural population in Punjab, followed by Hindus (26.51%), Christians (1.25%), and Muslims (.89%). From 1971-1981, Muslims experienced the greatest increase (49.29%). Sikhs grew by 20.74% and Hindus by 9.02%. The Sikhs high growth rate was due to 1) a new technique for counting religious affiliation in which all members of a household are considered the same religion as the head of household and 2) conversion of Hindus to Sikhism. Hindus had a low growth rate because 1) the new method of counting religious affiliation and 2) rural-urban migration. The area with the lowest population increase resulted from industrialists and other nonagriculturists buying farmland, causing the agriculturists to move away to less desirable land. Conclusions are 1) the sharp rural-urban division along religious lines should be lessened, 2) Sikhs' lag in urbanization and

  6. A phenomenological theory of world population growth and global problems

    CERN Document Server

    Kapitza, Sergei P

    1996-01-01

    Of all global problems world population growth is the most significant one. To describe this process in its past and project it into the future a mathematical model is worked out. It treats the world population as an entity, seen as an open and evolv The approach is phenomenological and growth over very many generations is assumed to be selfsimilar and described by scaling. In terms of kinetics, the growth rate is proportional to the square of the total number of people and the nonlinear hyperbol of all mechanisms that contribute to our development in a collective interactive process. The model gives an estimate of the beginning of human evolution c.a. 4.4 million years ago and of the total number of people who ever lived c.a. 100 billion. In the scope of the model large scale cycles defined by history and anthropology are shown to be uniformly spaced in time on a logarithmic scale, expressing and inherent periodicity. As we approach the present, this progression of cycles is now termo transition. This is a s...

  7. Population growth and United States politics in the 1970s.

    Science.gov (United States)

    Nash, A E

    1973-01-01

    The 2 themes of this century, increasing environmental fragility and increasing human demands on government, are underlined by the failure of government to effectively govern, and the complex technology and modern communication systems which further divide the developing nations from the developed ones. Population stabilization may help relieve the tension between increasing expectation from government and the fiscal bind in 3 ways: 1)a higher per capita income would increase per capita government revenue which would have a better chance of meeting citizen expectations, 2)a moderately redistributive effect on personal income might occur by decreasing unwanted fertility through the dynamics of economics and increasing the role of government in elevating living standards, and 3)with reduction of government expenditure per capita, the cost of providing any given level of service would decrease. The nuclear age has altered the concept of what constitutes national security. Rapid population growth in the developing countries is also significant, and the United States economy depends on overseas investment. A constructive foreign policy, as opposed to neoimperialism or isolationism, is recommended to help influence world population growth.

  8. The m=1 diocotron instability in single species plasmas

    International Nuclear Information System (INIS)

    Finn, J. M.; Castillo-Negrete, D. del; Barnes, D. C.

    1999-01-01

    According to conventional theory based on the drift-Poisson equations, the m=1 diocotron mode is stable, even for hollow density profiles. However, experiments [C. F. Driscoll, Phys. Rev. Lett. 64, 645 (1990)] show instability for this mode. These results have remained unexplained since 1990. We have found two effects, related to compression parallel to the magnetic field, which lead to instability with growth rates and other properties in good agreement with the experiments. The first is due to curvature of the sheaths at the ends of the trap. The second is the free boundary effect due to the linearized perturbation of the plasma length. These effects are described in terms of the modified drift-Poisson model, which states the conservation of the line integrated density. The modified drift-Poisson equations derived are analogous to the shallow water equations of geophysical fluid dynamics (GFD), with the line integrated density corresponding to the potential vorticity. This is explained in more detail in [del-Castillo-Negrete et al., this volume]. More recent experimental results [A. A. Kabantsev and C. F. Driscoll, this volume] show agreement over a wider range of parameters than the original experiments. We study the m=2 mode and show that curvature and free boundary effects can increase the growth rate, but it is still small compared to that of the m=1 mode for realistic parameters, and the critical hollowness for stability is much greater. Results are also shown for m=1 modes in the analogous GFD system. It is shown that topography variation in cylindrical geometry and free surface effects both lead to instability with properties similar to those in the plasma models

  9. Growth in an English population from the Industrial Revolution.

    Science.gov (United States)

    Mays, S; Brickley, M; Ives, R

    2008-05-01

    The rapid urbanization of the Industrial Revolution in 18th-19th century England presented new health challenges. Our aim is to investigate using English skeletal remains whether the living conditions for an urban working class group in the Industrial Revolution negatively impacted upon their skeletal growth compared with a population from a rural agrarian parish. The Industrial Revolution skeletal material is from St Martin's Churchyard, Birmingham (SMB), West Midlands. It dates primarily from the first half of the nineteenth century when Birmingham was a major manufacturing center. The rural group is from Wharram Percy (WP), North Yorkshire, and dates from 10th-19th century AD. The methodology involves plotting diaphyseal bone lengths versus dental age for subadults. No overall difference was found between the two populations in bone length-for-age among the 2- to 18-year cohort. However the younger parts of the SMB cohort were smaller than at WP; the opposite was true of the older parts of the cohort. Growth rate, as inferred from crosssectional data, appeared greater at SMB than at WP. The only result consistent with expectations is the larger bone dimensions in young children from WP, but this likely reflects prolonged breastfeeding at WP not differences in urban and rural environments. That the deleterious health effects that we know accompanied the major transition in human society from a rural agrarian to an urban industrialized living environment should be little manifest in skeletal endochondral growth data is discouraging for those who would use such methodology to monitor health in earlier populations. (c) 2008 Wiley-Liss, Inc.

  10. [Environmental pollution and population growth in Latin America].

    Science.gov (United States)

    Viel, B

    1983-01-01

    3 factors are always involved in causation of infectious disease: the causal organism, an adverse environment, and nutritional status. As knowledge of degenerative and mental illnesses advances, their relationship to environmental problems becomes clearer. Health in the human being as in all living things is the product of ecological equilibrium. In countries with high mortality rates, the majority of deaths occur in the early years of life. Countries enjoying low mortality rates are those that have protected themselves against environmental deterioration. The Roman civilization, the 1st to have large cities, built aqueducts to protect the water supply from contamination. With the disappearance of the Roman Empire the concern for purity of the water supply also disappeared, and the cities of the Middle Ages became breeding grounds for epidemics. In the early 19th century John Snow demonstrated the role of water in the transmission of cholera and thereafter the concern with potable water and sewage disposal was reborn. The Industrial Revolution eventually allowed sufficient accumulation of wealth to permit improved nutrition. Environmental sanitation and improved food supply produced a new ecological equilibrium, and Western Europe began to have lower and lower mortality rates. Paralleling the decline in deaths a new spirit of responsible parenthood and delayed marriage was lowering birth rates. Population growth, which never exceeded 1%, had the additional escape valve of emigration to America and Australia. The true cause of environmental degradation is man. When human beings were few their contaminants were readily obsorbed by the environment, but as they proliferate the environment is increasingly unable to absorb their pollution by natural processes. Industrial fumes, deforestation, and polluted rivers are only the symptoms of contamination. In the developed countries, technological innovations minimizing industrial pollution and lower population growth are

  11. Social policy and population growth in South-East Asia.

    Science.gov (United States)

    You Poh Seng Rao, B; Shantakumar, G

    1974-01-01

    Social and population policies are considered for the 10 countries comprising Southeast Asia--Burma, Indonesia, the Khmer Republic, Laos, Malaysia, the Philippines, Singapore, Thailand, North Vietnam, and South Vietnam. All but Singapore have high fertility rates and Burma, Indonesia, the Khmer Republic, Laos and the two Vietnams have high mortality rates also. Government expenditures for education and social security systems is expanding throughout the region and it is hoped that their continued growth will contribute substantially to the effective implementation of population policies. Population policies in the 5 countries which have them are discussed. These are Indonesia, Malaysia, the Philippines, Singapore, and Thailand. It is noted, however, that declaration of policy is but the first step. Strategies and programs differ from one country to the next and depend very much on the stage of development, level of literacy, degree of urbanization, and other factors. Family planning activities generally are endogenous to urban social systems but exogenous to rural social systems. Thus, the rural elite has a large role to play in making population policies an integral part of rural life. The possibility is considered of developing workable incentive packages integrating health, education, and social security benefits with suitable emphasis on fertility reduction.

  12. Nexus between population and economic growth in india: a co-integration analysis

    OpenAIRE

    Komol Singha; M.S. Jaman

    2013-01-01

    The study of population and economic growth has been the subject of intense debates between the two schools of thought. One relates to pessimistic opinion that population has a negative impact on economic growth while the other is convinced that the effect is positive. Recently, third group argues that the rise in population is neutral on economic growth. However, till date, the issue remains inconclusive. To analyse causality, using 51 years time series data of GDP and population growth, a G...

  13. Global warming, population growth, and natural resources for food production.

    Science.gov (United States)

    Pimentel, D

    1991-01-01

    Destruction of forests and the considerable burning of fossil fuels is directly causing the level of carbon dioxide and other greenhouse gases including methane, carbon monoxide, and nitrous oxide in the atmosphere to rise. Population growth in the US and the world indirectly contributes to this global warming. This has led the majority of scientists interested in weather and climate to predict that the planet's temperature will increase from 1.5 to 4.5 degrees Celsius by 2050. These forecasted climactic changes will most likely strongly affect crop production. Specifically these scientists expect the potential changes in temperature, moisture, carbon dioxide, and pests to decrease food production in North America. The degree of changes hinges on each crop and its environmental needs. If farmers begin using improved agricultural technology, the fall in crop yields can be somewhat counterbalanced. Even without global warming, however, agriculture in North America must embrace sensible ecological resource management practices such as conserving soil, water, energy, and biological resources. These sustainable agricultural practices would serve agriculture, farmers, the environment, and society. Agriculturalists, farmers, and society are already interested in sustainable agriculture. Still scientists must conduct more research on the multiple effects of potential global climate change on many different crops under various environmental conditions and on new technologies that farmers might use in agricultural production. We must cut down our consumption of fossil fuel, reduce deforestation, erase poverty, and protect our soil, water, and biological resources. The most important action we need to take, however, is to check population growth.

  14. Predicting impacts of future human population growth and development on occupancy rates of forest-dependent birds

    Science.gov (United States)

    Brown, Michelle L.; Donovan, Therese; Schwenk, W. Scott; Theobald, David M.

    2014-01-01

    Forest loss and fragmentation are among the largest threats to forest-dwelling wildlife species today, and projected increases in human population growth are expected to increase these threats in the next century. We combined spatially-explicit growth models with wildlife distribution models to predict the effects of human development on 5 forest-dependent bird species in Vermont, New Hampshire, and Massachusetts, USA. We used single-species occupancy models to derive the probability of occupancy for each species across the study area in the years 2000 and 2050. Over half a million new housing units were predicted to be added to the landscape. The maximum change in housing density was nearly 30 houses per hectare; however, 30% of the towns in the study area were projected to add less than 1 housing unit per hectare. In the face of predicted human growth, the overall occupancy of each species decreased by as much as 38% (ranging from 19% to 38% declines in the worst-case scenario) in the year 2050. These declines were greater outside of protected areas than within protected lands. Ninety-seven percent of towns experienced some decline in species occupancy within their borders, highlighting the value of spatially-explicit models. The mean decrease in occupancy probability within towns ranged from 3% for hairy woodpecker to 8% for ovenbird and hermit thrush. Reductions in occupancy probability occurred on the perimeters of cities and towns where exurban development is predicted to increase in the study area. This spatial approach to wildlife planning provides data to evaluate trade-offs between development scenarios and forest-dependent wildlife species.

  15. Population growth, fecundity, and survivorship in recovering populations of bighorn sheep

    Science.gov (United States)

    Singer, F.J.; Williams, E.; Miller, M.W.; Zeigenfuss, L.C.

    2000-01-01

    The single greatest obstacle to the restoration of large, healthy, populations of bighorn sheep (Ovis canadensis) in the western United States is epizootic outbreaks of bronchopneumonia that may kill 20–100% of the animals in populations. Although the species is capable of rapid initial growth rates following restoration into new habitat (λ = 1.23–1.30 have been observed), these rates of increase are typical only a few years following the release of a population, and then most populations either decline to extirpation or remnant status (Moraxella sp., and parainfluenza-3 and bluetongue (BT) viruses. Pregnancy rates of adult ewes were not different in increasing or decreasing populations (pooled rate = 0.93; p = 0.57), but pregnancy rates of yearlings were lower (0.00 for decreasing vs. 0.33 for increasing populations), initial production of lambs and annual recruitment of lambs was lower (0.14, decreasing vs. 0.66, p < 0.05). Adult survival was lower during the first year of an epizootic, 0.62, in one population, but recovered to 0.85 by the second and subsequent years. Survival of adult rams was variable in diseased populations; in two populations rams appeared to be disproportionately impacted, but in a third population rams survived better during the epizootic. In all the increasing park (unhunted) populations, adult ram survival (0.94 ± 0.01) was higher than adult ewe survival (0.89 ± 0.02) (p = 0.10), in contrast to published information from hunted populations where ram survival was lower. Removal of about 20% of one population for restorations severely impacted one declining population. Removals of 12–20% appeared to be excessive and were not readily compensated for in the Canyonlands National Park desert bighorn population. Disease was a significant limiting factor to restoration of bighorn sheep in the study areas; six of 11 total recovering populations we monitored closely were negatively influenced by apparent disease at some time during

  16. Estimated impact of global population growth on future wilderness extent

    Science.gov (United States)

    Dumont, E.

    2012-06-01

    Wilderness areas in the world are threatened by the environmental impacts of the growing global human population. This study estimates the impact of birth rate on the future surface area of biodiverse wilderness and on the proportion of this area without major extinctions. The following four drivers are considered: human population growth (1), agricultural efficiency (2), groundwater drawdown by irrigation (3), and non-agricultural space used by humans (buildings, gardens, roads, etc.) (4). This study indicates that the surface area of biodiverse unmanaged land will reduce with about 5.4% between 2012 and 2050. Further, it indicates that the biodiverse land without major extinctions will reduce with about 10.5%. These percentages are based on a commonly used population trajectory which assumes that birth rates across the globe will reduce in a similar way as has occurred in the past in many developed countries. Future birth rate is however very uncertain. Plausible future birth rates lower than the expected rates lead to much smaller reductions in surface area of biodiverse unmanaged land (0.7% as opposed to 5.4%), and a reduction in the biodiverse land without major extinctions of about 5.6% (as opposed to 10.5%). This indicates that birth rate is an important factor influencing the quality and quantity of wilderness remaining in the future.

  17. World population growth, family planning, and American foreign policy.

    Science.gov (United States)

    Sharpless, J

    1995-01-01

    The US decision since the 1960s to link foreign policy with family planning and population control is noteworthy for its intention to change the demographic structure of foreign countries and the magnitude of the initiative. The current population ideologies are part of the legacy of 19th century views on science, morality, and political economy. Strong constraints were placed on US foreign policy since World War II, particularly due to presumptions about the role of developing countries in Cold War ideology. Domestic debates revolved around issues of feminism, birth control, abortion, and family political issues. Since the 1960s, environmental degradation and resource depletion were an added global dimension of US population issues. Between 1935 and 1958 birth control movements evolved from the ideologies of utopian socialists, Malthusians, women's rights activists, civil libertarians, and advocates of sexual freedom. There was a shift from acceptance of birth control to questions about the role of national government in supporting distribution of birth control. Immediately postwar the debates over birth control were outside political circles. The concept of family planning as a middle class family issue shifted the focus from freeing women from the burdens of housework to making women more efficient housewives. Family planning could not be taken as a national policy concern without justification as a major issue, a link to national security, belief in the success of intervention, and a justifiable means of inclusion in public policy. US government involvement began with agricultural education, technological assistance, and economic development that would satisfy the world's growing population. Cold War politics forced population growth as an issue to be considered within the realm of foreign policy and diplomacy. US government sponsored family planning was enthusiastic during 1967-74 but restrained during the 1980s. The 1990s has been an era of redefinition of

  18. A stochastic population model to evaluate Moapa dace (Moapa coriacea) population growth under alternative management scenarios

    Science.gov (United States)

    Perry, Russell W.; Jones, Edward; Scoppettone, G. Gary

    2015-07-14

    The primary goal of this research project was to evaluate the response of Moapa dace (Moapa coriacea) to the potential effects of changes in the amount of available habitat due to human influences such as ground water pumping, barriers to movement, and extirpation of Moapa dace from the mainstem Muddy River. To understand how these factors affect Moapa dace populations and to provide a tool to guide recovery actions, we developed a stochastic model to simulate Moapa dace population dynamics. Specifically, we developed an individual based model (IBM) to incorporate the critical components that drive Moapa dace population dynamics. Our model is composed of several interlinked submodels that describe changes in Moapa dace habitat as translated into carrying capacity, the influence of carrying capacity on demographic rates of dace, and the consequent effect on equilibrium population sizes. The model is spatially explicit and represents the stream network as eight discrete stream segments. The model operates at a monthly time step to incorporate seasonally varying reproduction. Growth rates of individuals vary among stream segments, with growth rates increasing along a headwater to mainstem gradient. Movement and survival of individuals are driven by density-dependent relationships that are influenced by the carrying capacity of each stream segment.

  19. Contribution of population growth to per capita income and sectoral output growth in Japan, 1880-1970.

    Science.gov (United States)

    Yamaguchi, M; Kennedy, G

    1984-09-01

    The authors measured the positive and negative contributions of population and labor force growth to the growth of per capita income and sectoral output in Japan in the 1880-1970 period. A 2-sector growth accounting model that treats population and labor growth as separate variables was used. 3 alternative methods were used: the Residual method, the Verdoorn method, and the factor augmenting rate method. The total contribution of population cum labor growth to per capita income growth tended to be negative in the 1880-1930 period and positive in the 1930-40 and 1950-70. Over the 1880-1970 period as a whole, population cum labor growth made a positive contribution to per capita income growth under the Residual method (0.35%/year), the factor augmenting rate method (0.29%/year), and the Verdoorn method (0.01%/year). In addition, population cum labor growth contributed positively to sectoral output growth. The average contribution to agricultural output growth ranged from 1.03% (Verdoorn) - 1.46%/year (factor augmenting rate), while the average contribution to nonagricultural output growth ranged from 1.22% (Verdoorn) - 1.60%/year (Residual). Although these results are dependent on the model used, the fact that all 3 methods yielded consistent results suggests that population cum labor growth did make a positive contribution to per capita income and sectoral output growth in Japan. These findings imply that in economies where the rate of technical change in agricultural and nonagricultural sectors exceeds population growth, policies that reduce agricultural elasticities may be preferable; on the other hand, policies that reduce agricultural elasticities are to be avoided in economies with low rates of technical change. Moreover, in the early stages of economic development, policies that increase agricultural income and price elasticities should be considered.

  20. Development Planning and Population Growth and Redistribution in the Republic of Iraq.

    Science.gov (United States)

    El Attar, M. E.; Salman, A. D.

    Utilizing the 1947, 1957, and l965 census data and the 1970 preliminary population count, the relationship between population growth and redistribution and development planning in Iraq was examined. Trends in rural-urban population growth, migration, and population redistribution were examined as they pertained to the socioeconomic development…

  1. An equivalence theorem concerning population growth in a variable environment

    Directory of Open Access Journals (Sweden)

    Ray Redheffer

    2003-01-01

    Full Text Available We give conditions under which two solutions x and y of the Kolmogorov equation x˙=xf(t,x satisfy limy(t/x(t=1 as t→∞. This conclusion is important for two reasons: it shows that the long-time behavior of the population is independent of the initial condition and it applies to ecological systems in which the coefficients are time dependent. Our first application is to an equation of Weissing and Huisman for growth and competition in a light gradient. Our second application is to a nonautonomous generalization of the Turner-Bradley-Kirk-Pruitt equation, which even before generalization, includes several problems of ecological interest.

  2. Population and labour force growth and patterns in ASEAN countries.

    Science.gov (United States)

    Saw, S

    1988-01-01

    "The paper shows that the diverse labor dimensions prevailing in the ASEAN region can be attributed to changes in the structure of the society and economy in the course of recent economic development. It observes the considerable variety in the growth of the population and its effect on the labor force in the ASEAN region.... The paper details the similarity and diversity in the level and type of labor force participation rates. A common feature shared by ASEAN countries is a general pattern in the age-specific participation rate of men. In contrast, the women, aside from participating in the labor force at a much lower level than men at almost all ages, display diverse patterns of participation over the working age range. Lastly, the distribution of the labor force according to major industrial sectors in the six ASEAN countries is presented...." excerpt

  3. The problem of population and growth: a review of the literature from Malthus to contemporary models of endogenous population and endogenous growth.

    Science.gov (United States)

    Ehrlich, I; Lui, F

    1997-01-01

    This review traces the evolution of literature on population and economic growth through the main paradigms suggested to explain the observed covariation of per capita income and population levels (or their rates of growth) over time and space, and determine which public policies will improve the human condition. As the main paradigms evolved, key variables were progressively treated as endogenous (instead of exogenous) to the growth process. After the introduction, section 2 looks at the "classical model" of Malthusian population theory and its refinements. Section 3 identifies empirical data that bears on the secular and cross-sectional association between levels of rates of growth of population and per capita income. The inconsistency of these data with the classical model helps explain declining interest in this model over time and increased interest in a more systematic type of population and growth theory. The beginning of this new interest is traced in section 4 with a look at the "neo-classical growth model" and the reformulated theory of population, which was based on Becker's work on fertility behavior. The first line of inquiry branching from these theoretical works (section 5) treats population as an endogenous variable in static and dynamic settings. The second line of inquiry (section 6) analyzes population and growth within a unified model of growth and development. In section 7, recent studies of key policy issues (population control policies, mandatory social security schemes) are surveyed. The concluding section notes that contemporary research must face the challenge of providing additional insights into longevity as an aspect of economic growth and development and of developing a model of endogenous population and economic growth based on heterogeneous agents.

  4. Grassland ecology and population growth: striking a balance.

    Science.gov (United States)

    Hou, D; Duan, C; Zhang, D

    2000-06-01

    Degradation of forest and grasslands in western China attributes to the soil erosion and desertification in the country. Researchers have established that the primary reason for the degradation of grasslands is overgrazing, which in turn is caused by a number of factors, including over-population and over-reliance on animal husbandry. In addition, the existing administrative system has also proved ineffective in ensuring sustainable development. On contrary, many local governments even encourage exploitative development of grassland; thus, localities opened up grassland for growing crops in an effort to increase income. According to estimates, degraded grassland accounts for more than one-third of utilizable acreage and another one-third suffers from a profusion of rats and pests. To redress the situation, central government should implement strategies in achieving sustainable development, such as providing banking and tax incentives for the development of the secondary and tertiary industries, and supporting education and training of youths from herding areas. Moreover, government should increase spending on infrastructural construction and ecological preservation. Finally, the family planning program needs to be enforced to control population growth and improve the quality of peoples¿ lives.

  5. The impact of accelerating faster than exponential population growth on genetic variation.

    Science.gov (United States)

    Reppell, Mark; Boehnke, Michael; Zöllner, Sebastian

    2014-03-01

    Current human sequencing projects observe an abundance of extremely rare genetic variation, suggesting recent acceleration of population growth. To better understand the impact of such accelerating growth on the quantity and nature of genetic variation, we present a new class of models capable of incorporating faster than exponential growth in a coalescent framework. Our work shows that such accelerated growth affects only the population size in the recent past and thus large samples are required to detect the models' effects on patterns of variation. When we compare models with fixed initial growth rate, models with accelerating growth achieve very large current population sizes and large samples from these populations contain more variation than samples from populations with constant growth. This increase is driven almost entirely by an increase in singleton variation. Moreover, linkage disequilibrium decays faster in populations with accelerating growth. When we instead condition on current population size, models with accelerating growth result in less overall variation and slower linkage disequilibrium decay compared to models with exponential growth. We also find that pairwise linkage disequilibrium of very rare variants contains information about growth rates in the recent past. Finally, we demonstrate that models of accelerating growth may substantially change estimates of present-day effective population sizes and growth times.

  6. POPULATION GROWTH AND PREFERENCE CHANGE IN A GENERALIZED SOLOW GROWTH MODEL WITH GENDER TIME DISTRIBUTIONS

    Directory of Open Access Journals (Sweden)

    Wei-Bin Zhang

    2016-09-01

    Full Text Available The study builds a model of dynamic interactions between the birth rate, the mortality rate, the population, wealth accumulation, time distribution between work, leisure and children caring, habit formation and preference change. The production technology and markets are built on the Solow growth model. We base our modeling the population dynamics on the Haavelmo population model and the Barro-Becker fertility choice model. This study takes account of habit formation and preference change. Although it is influenced by the Ramsey growth theory with time preference and habit formation, it uses Zhang’s approach to the household with habit formation and preference change. We synthesize different dynamic forces in a compact framework, using the utility function proposed by Zhang. Analytically, we focus on transitional processes as well as economic equilibrium. As the economic system is given by autonomous nonlinear differential equations, it is not easy to analyze its behavior. We simulate the model to demonstrate the existence of an equilibrium point and plot the motion of the dynamic system. We examine the effects of changes in weights given to the habit stock of children, the wife’s wage rate having negative impact on the propensity to have children, the wife weighing less the habit stock of leisure time, the wife’s habit stock of leisure time having negative impact on the husband’s propensity to use leisure time, the wife’s wage rate having negative impact on the husband’s propensity to use leisure time, woman’s human capital being improved, a rise in the total factor productivity, and the mother spending more time on each child fostering.

  7. Economic growth and welfare of the population in Russia: historical overview and management solutions

    OpenAIRE

    DANILOV K.D.

    2016-01-01

    The article deals with the issues of economic growth in Russia and other countries, the relationship between economic growth and welfare of the population, a mismatch of high results of economic development and the rate of growth of national income. Historical overview of the theories of economic growth and appropriate management decisions is given.

  8. The role of population on economic growth and development: evidence from developing countries

    OpenAIRE

    Atanda, Akinwande A.; Aminu, Salaudeen B.; Alimi, Olorunfemi Y.

    2012-01-01

    The precise relationship between population growth and per capita income has been inconclusive in the literature and the nexus has been found not clearly explain the determinants of rapid population growth in developing countries that lacks fertility control and management framework. This forms the rationale for this study to access the trend of factors that influence rapid population growth in developing countries between 1980 and 2010. This paper examined the comparative trend review of pop...

  9. An Investigative Alternative to Single-Species Dissection in the Introductory Biology Laboratory

    Science.gov (United States)

    Carlin, Joel L.

    2010-01-01

    Dissections of single species (e.g., fetal pig) are a common student learning activity in introductory biology courses. Such dissections demonstrate location of anatomical parts and provide dissection practice but provide less opportunity for student critical thinking, numeracy and demonstration of the scientific method. A comparative anatomy lab…

  10. Cover crops in mixtures do not use water differently than single-species plantings

    Science.gov (United States)

    Some recent statements have been made about the benefits of growing cover crops in mixtures as compared with single-species plantings of cover crops. One of those stated benefits is greatly reduced water use by cover crops grown in mixtures. The objectives of this study were to characterize soil wat...

  11. Estimation and computation of the growth rate in Leslie's and Lotka's population models.

    Science.gov (United States)

    Anderson, D H

    1975-09-01

    Leslie's or Lotka's population model has a rate of natural increase (lambda or r) which represents the growth rate of the population and characterizes the ability of the population to attain a stable age distribution. In this article are presented upper and lower bounds on that rate, primarily in terms of the net reproduction rate and other commonly used parameters of the population. Also a discussion is given of quadratically convergent numerical iterative methods of computing the growth rate.

  12. Molecular analysis of the freshwater prawn Macrobrachium olfersii (Decapoda, Palaemonidae) supports the existence of a single species throughout its distribution.

    Science.gov (United States)

    Rossi, Natália; Mantelatto, Fernando Luis

    2013-01-01

    Macrobrachium olfersii is an amphidromous freshwater prawn, widespread along the eastern coasts of the Americas. This species shows great morphological modifications during ontogenesis, and several studies have verified the existence of a wide intraspecific variation. Because of this condition, the species is often misidentified, and several synonyms have been documented. To elucidate these aspects, individuals of M. olfersii from different populations along its range of distribution were investigated. The taxonomic limit was established, and the degree of genetic variability of this species was described. We extracted DNA from 53 specimens of M. olfersii, M. americanum, M. digueti and M. faustinum, which resulted in 84 new sequences (22 of 16S mtDNA, 45 of Cythocrome Oxidase I (COI) mtDNA, and 17 of Histone (H3) nDNA). Sequences of three genes (single and concatenated) from these species were used in the Maximum Likelihood and Bayesian Inference phylogenetic analyses and COI sequences from M. olfersii were used in population analysis. The genetic variation was evaluated through the alignment of 554 bp from the 16S, 638 bp from the COI, and 338 bp from the H3. The rates of genetic divergence among populations were lower at the intraspecific level. This was confirmed by the haplotype net, which showed a continuous gene flow among populations. Although a wide distribution and high morphological intraspecific variation often suggest the existence of more than one species, genetic similarity of Caribbean and Brazilian populations of M. olfersii supported them as a single species.

  13. Molecular analysis of the freshwater prawn Macrobrachium olfersii (Decapoda, Palaemonidae supports the existence of a single species throughout its distribution.

    Directory of Open Access Journals (Sweden)

    Natália Rossi

    Full Text Available Macrobrachium olfersii is an amphidromous freshwater prawn, widespread along the eastern coasts of the Americas. This species shows great morphological modifications during ontogenesis, and several studies have verified the existence of a wide intraspecific variation. Because of this condition, the species is often misidentified, and several synonyms have been documented. To elucidate these aspects, individuals of M. olfersii from different populations along its range of distribution were investigated. The taxonomic limit was established, and the degree of genetic variability of this species was described. We extracted DNA from 53 specimens of M. olfersii, M. americanum, M. digueti and M. faustinum, which resulted in 84 new sequences (22 of 16S mtDNA, 45 of Cythocrome Oxidase I (COI mtDNA, and 17 of Histone (H3 nDNA. Sequences of three genes (single and concatenated from these species were used in the Maximum Likelihood and Bayesian Inference phylogenetic analyses and COI sequences from M. olfersii were used in population analysis. The genetic variation was evaluated through the alignment of 554 bp from the 16S, 638 bp from the COI, and 338 bp from the H3. The rates of genetic divergence among populations were lower at the intraspecific level. This was confirmed by the haplotype net, which showed a continuous gene flow among populations. Although a wide distribution and high morphological intraspecific variation often suggest the existence of more than one species, genetic similarity of Caribbean and Brazilian populations of M. olfersii supported them as a single species.

  14. Comparison of customised growth charts v. standard population ...

    African Journals Online (AJOL)

    Of the patients, 44 had type 1, 66 type 2 and 173 gestational diabetes. The growth of 79/283 fetuses would .... with diabetes. In keeping with this trend, more women are also being diagnosed with. GDM. These women have an increased risk of delivering macrosomic and growth- restricted babies, with their related risks.

  15. Comparative Study of Population Growth and Agricultural Change: C - Case Study of India. Asian Population Studies Series No. 23.

    Science.gov (United States)

    United Nations Economic and Social Commission for Asia and the Pacific, Bangkok (Thailand).

    This report, the third in a series of five reports of the Comparative Study of Population Growth and Agricultural Change, describes a study of the two states of India (Punjaband and Orissa) which attempted to clarify the relationship between population pressure and agricultural change through a time series analysis. This study: (1) outlines trends…

  16. The size and growth of state populations in the United States

    OpenAIRE

    Kwok Tong Soo

    2012-01-01

    This paper explores the population distribution across U.S. states over time. We test for Zipf's Law on the size distribution of state populations and Gibrat's Law for the growth of state populations. State populations follow a lognormal distribution more closely than they do a Zipf or Pareto distribution. State population growth is negatively related to current state population in the 19th century but not in the 20th century, and is positively related to market potential in the 20th century ...

  17. Urban and rural population growth in a spatial panel of municipalities

    NARCIS (Netherlands)

    Costa da Silva, Diego Firmino; Elhorst, J. Paul; Silveira Neto, Raul da Mota

    2017-01-01

    Urban and rural population growth in a spatial panel of municipalities. Regional Studies. Using Bayesian posterior model probabilities and data pertaining to 3659 Brazilian minimum comparable areas (MCAs) over the period 1970-2010, two theoretical settings of population growth dynamics resulting in

  18. The effect of population aging on health expenditure growth : A critical review

    NARCIS (Netherlands)

    de Meijer, C.; Wouterse, B.; Polder, J.J.; Koopmanschap, M.

    2013-01-01

    Although the consequences of population aging for growth in health expenditures have been widely investigated, research on this topic is rather fragmented. Therefore, these consequences are not fully understood. This paper reviews the consequences of population aging for health expenditure growth in

  19. The Solow model in discrete time and decreasing population growth rate

    OpenAIRE

    Juan Sebastián Pereyra; Juan Gabriel Brida

    2008-01-01

    This paper reformulates the neoclassical Solow-Swan model of economic growth in discrete time by introducing a generic population growth law that verifies the following properties: 1) population is strictly increasing and bounded 2) the rate of growth of population is decreasing to zero as time tends to infinity. We show that in the long run the capital per worker of the model converges to the non-trivial steady state of the Solow Swan model with zero labor growth rate. In addition we prove t...

  20. Taking Exception. Reduced mortality leads to population growth: an inconvenient truth.

    Science.gov (United States)

    Shelton, James D

    2014-05-01

    Reduced mortality has been the predominant cause of the marked global population growth over the last 3/4 of a century. While improved child survival increases motivation to reduce fertility, it comes too little and too late to forestall substantial population growth. And, beyond motivation, couples need effective means to control their fertility. It is an inconvenient truth that reducing child mortality contributes considerably to the population growth destined to compromise the quality of life of many, particularly in sub-Saharan Africa. Vigorous child survival programming is of course imperative. Wide access to voluntary family planning can help mitigate that growth and provide many other benefits.

  1. Population Dynamics and Long-Run Economic Growth

    OpenAIRE

    Casey, Gregory; Galor, Oded

    2014-01-01

    This paper applies insights from theoretical and empirical research in economic growth to analyze the impacts of policies affecting fertility, migration and human capital accumulation on growth and poverty alleviation. It underlines the tradeoff between having more children and investing more resources in the human capital of each child as a critical force in devising policies that will alleviate hardship and generate long-term prosperity. In developing countries, policies increasing the retu...

  2. Population.

    Science.gov (United States)

    International Planned Parenthood Federation, London (England).

    In an effort to help meet the growing interest and concern about the problems created by the rapid growth of population, The International Planned Parenthood Federation has prepared this booklet with the aim of assisting the study of the history and future trends of population growth and its impact on individual and family welfare, national,…

  3. The demographic consequences of mutualism: ants increase host-plant fruit production but not population growth.

    Science.gov (United States)

    Ford, Kevin R; Ness, Joshua H; Bronstein, Judith L; Morris, William F

    2015-10-01

    The impact of mutualists on a partner's demography depends on how they affect the partner's multiple vital rates and how those vital rates, in turn, affect population growth. However, mutualism studies rarely measure effects on multiple vital rates or integrate them to assess the ultimate impact on population growth. We used vital rate data, population models and simulations of long-term population dynamics to quantify the demographic impact of a guild of ant species on the plant Ferocactus wislizeni. The ants feed at the plant's extrafloral nectaries and attack herbivores attempting to consume reproductive organs. Ant-guarded plants produced significantly more fruit, but ants had no significant effect on individual growth or survival. After integrating ant effects across these vital rates, we found that projected population growth was not significantly different between unguarded and ant-guarded plants because population growth was only weakly influenced by differences in fruit production (though strongly influenced by differences in individual growth and survival). However, simulations showed that ants could positively affect long-term plant population dynamics through services provided during rare but important events (herbivore outbreaks that reduce survival or years of high seedling recruitment associated with abundant precipitation). Thus, in this seemingly clear example of mutualism, the interaction may actually yield no clear benefit to plant population growth, or if it does, may only do so through the actions of the ants during rare events. These insights demonstrate the value of taking a demographic approach to studying the consequences of mutualism.

  4. Population Ageing, Retirement Age Extension and Economic Growth in China A Dynamic General Equilibrium Analysis

    OpenAIRE

    Xiujian Peng; Yinhua Mai

    2013-01-01

    China is experiencing rapid population ageing with the proportion of the population aged 65 and above projected to increase almost threefold between 2010 and 2050. The growth of the working age population is expected to stop approximately in 2015 and to turn strongly negative. China's low retirement age compounds the ageing problem. One means to mitigate the negative effects of shrinking labour force on economic growth is to stimulate labour force participation among the current working age p...

  5. The demographic consequences of mutualism: ants increase host-plant fruit production but not population growth

    Science.gov (United States)

    Kevin Ford; Joshua H. Ness; Judith L. Bronstein; William F. Morris

    2015-01-01

    The impact of mutualists on a partner’s demography depends on how they affect the partner’s multiple vital rates and how those vital rates, in turn, affect population growth. However, mutualism studies rarely measure effects on multiple vital rates or integrate them to assess the ultimate impact on population growth. We used vital rate data, population models and...

  6. Regulatory design governing progression of population growth phases in bacteria.

    Directory of Open Access Journals (Sweden)

    Agustino Martínez-Antonio

    Full Text Available It has long been noted that batch cultures inoculated with resting bacteria exhibit a progression of growth phases traditionally labeled lag, exponential, pre-stationary and stationary. However, a detailed molecular description of the mechanisms controlling the transitions between these phases is lacking. A core circuit, formed by a subset of regulatory interactions involving five global transcription factors (FIS, HNS, IHF, RpoS and GadX, has been identified by correlating information from the well- established transcriptional regulatory network of Escherichia coli and genome-wide expression data from cultures in these different growth phases. We propose a functional role for this circuit in controlling progression through these phases. Two alternative hypotheses for controlling the transition between the growth phases are first, a continuous graded adjustment to changing environmental conditions, and second, a discontinuous hysteretic switch at critical thresholds between growth phases. We formulate a simple mathematical model of the core circuit, consisting of differential equations based on the power-law formalism, and show by mathematical and computer-assisted analysis that there are critical conditions among the parameters of the model that can lead to hysteretic switch behavior, which--if validated experimentally--would suggest that the transitions between different growth phases might be analogous to cellular differentiation. Based on these provocative results, we propose experiments to test the alternative hypotheses.

  7. Regulatory design governing progression of population growth phases in bacteria.

    Science.gov (United States)

    Martínez-Antonio, Agustino; Lomnitz, Jason G; Sandoval, Santiago; Aldana, Maximino; Savageau, Michael A

    2012-01-01

    It has long been noted that batch cultures inoculated with resting bacteria exhibit a progression of growth phases traditionally labeled lag, exponential, pre-stationary and stationary. However, a detailed molecular description of the mechanisms controlling the transitions between these phases is lacking. A core circuit, formed by a subset of regulatory interactions involving five global transcription factors (FIS, HNS, IHF, RpoS and GadX), has been identified by correlating information from the well- established transcriptional regulatory network of Escherichia coli and genome-wide expression data from cultures in these different growth phases. We propose a functional role for this circuit in controlling progression through these phases. Two alternative hypotheses for controlling the transition between the growth phases are first, a continuous graded adjustment to changing environmental conditions, and second, a discontinuous hysteretic switch at critical thresholds between growth phases. We formulate a simple mathematical model of the core circuit, consisting of differential equations based on the power-law formalism, and show by mathematical and computer-assisted analysis that there are critical conditions among the parameters of the model that can lead to hysteretic switch behavior, which--if validated experimentally--would suggest that the transitions between different growth phases might be analogous to cellular differentiation. Based on these provocative results, we propose experiments to test the alternative hypotheses.

  8. Canadian Provincial Population Growth: Fertility, Migration, and Age Structure Effects

    Directory of Open Access Journals (Sweden)

    Edmonston, Barry

    2009-01-01

    Full Text Available AbstractThe effect of changes in rates of mortality, fertility, and migration depend not only on the age specific patterns and levels of these rates, but on the age structure of the population. In orderto remove the influences of the age structure and concentrate on the impact of the demographic rates themselves, a common practice is to analyze the influences of the rates for a standard age structure. This paper adapts the general approach of using a standard age structure to a stationary population equivalent (SPE model, and analyzes current population change, using the SPE model, for provinces of Canada. Below-replacement fertility levels are only partially offset by net immigration. The SPE model evidences the decrease in the eventual provincial populations brought about by the below replacement fertility. Out-migration for some provincesto other areas of Canada accentuates their eventual population decreases.RésuméLes effets des changements des taux de mortalité, fécondité, et de migration dépendent non seulement des modèles par âge et des niveaux de ces taux, mais aussi de la structure par âge de la population. Pour éliminer les influences de la structure par âge et se concentrer sur les effets des taux démographiques mêmes, une pratique courante est d’analyser les influences des taux par une structure par âge de norme. Cet article adapte l’approche générale de la structure parâge à un modèle de population stationnaire équivalente (PSE. Cet article analyse les changements de population, en utilisant le modèle de PSE, dans les provinces canadiennes. Le taux de fécondité inférieur au seuil de reproduction de la population n’est que légèrement compensé par l’immigration nette. Le modèle de PSE démontre le déclin des populations provinciales éventuelles causé par le taux de fécondité inférieur au seuil de reproduction de la population. Le taux d’émigration entre certaines provinces et reste du

  9. Effects of climate change on plant population growth rate and community composition change.

    Science.gov (United States)

    Chang, Xiao-Yu; Chen, Bao-Ming; Liu, Gang; Zhou, Ting; Jia, Xiao-Rong; Peng, Shao-Lin

    2015-01-01

    The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period (several decades) based on long-term monitoring data from two plots-Dinghushan Biosphere Reserve, China (DBR) and Barro Colorado Island, Panama (BCI)-that are located in tropical and subtropical regions. We proposed a relatively more concise index, Slnλ, which refers to an overall population growth rate based on the dominant species in a community. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades. This decrease was mainly caused by population development. The increasing temperature had a positive effect on population growth rates and community change rates. Our results promote understanding and explaining variations in population growth rates and community composition rates, and are helpful to predict population dynamics and population responses to climate change.

  10. Calculating second derivatives of population growth rates for ecology and evolution.

    Science.gov (United States)

    Shyu, Esther; Caswell, Hal

    2014-05-01

    1. Second derivatives of the population growth rate measure the curvature of its response to demographic, physiological or environmental parameters. The second derivatives quantify the response of sensitivity results to perturbations, provide a classification of types of selection and provide one way to calculate sensitivities of the stochastic growth rate. 2. Using matrix calculus, we derive the second derivatives of three population growth rate measures: the discrete-time growth rate λ, the continuous-time growth rate r = log λ and the net reproductive rate R 0 , which measures per-generation growth. 3. We present a suite of formulae for the second derivatives of each growth rate and show how to compute these derivatives with respect to projection matrix entries and to lower-level parameters affecting those matrix entries. 4. We also illustrate several ecological and evolutionary applications for these second derivative calculations with a case study for the tropical herb Calathea ovandensis .

  11. Population Dynamics in India and Implications for Economic Growth

    OpenAIRE

    David E. Bloom

    2011-01-01

    Demographic change in India is opening up new economic opportunities. As in many countries, declining infant and child mortality helped to spark lower fertility, effectively resulting in a temporary baby boom. As this cohort moves into working ages, India finds itself with a potentially higher share of workers as compared with dependents. If working-age people can be productively employed, India's economic growth stands to accelerate. Theoretical and empirical literature on the effect of demo...

  12. Noise-driven growth rate gain in clonal cellular populations

    OpenAIRE

    Hashimoto, Mikihiro; Nozoe, Takashi; Nakaoka, Hidenori; Okura, Reiko; Akiyoshi, Sayo; Kaneko, Kunihiko; Kussell, Edo; Wakamoto, Yuichi

    2016-01-01

    Differences between individuals exist even in the absence of genetic differences, e.g., in identical twins. Over the last decade, experiments have shown that even genetically identical microbes exhibit large cell-to-cell differences. In particular, the timing of cell division events is highly variable between single bacterial cells. The effect of this variability on long-term growth and survival of bacteria, however, remains elusive. Here, we present a striking finding showing that a bacteria...

  13. A question of dignity. Impact of rapid population growth on developing countries.

    Science.gov (United States)

    Osoro, A A

    1991-06-01

    Rapid population growth is one of the major contributing factors to the poverty and under-development of Third World countries--especially African countries, which boast the highest population growth rates in the world. Several factors are responsible for the rapid growth: a drop in mortality rates, a young population, improved standards of living, and attitudes and practices which favor high fertility. Africans view large families as an economic asset and as a symbol of worth and honor, and parents see it as security during old age. The ideal family size in Africa is 5 to 7 children. Because of its complex causes, curbing the rapid growth is not easy. In addition to strategic difficulties, population policies usually meet opposition, often from religious groups. So in order to gain acceptance, population programs need to be integrated with ongoing community development programs. Even though it often engenders opposition, family planning is more crucial then ever, as the rapid population growth continues to create an explosive situation. Rapid growth has led to uncontrolled urbanization, which has produced overcrowding, destitution, crime, pollution, and political turmoil. Rapid growth has outstripped increases in food production, and population pressure has led to the overuse of arable land and its destruction. Rapid growth has also hampered economic development and caused massive unemployment. 45% of Kenya's labor force is unemployed. Ultimately, rapid growth has undermined the quality of life of people. Society's responsibility extends beyond simply ensuring the survival of the population. Society must strive to provide people with a good life--one with dignity.

  14. The Revival of Population Growth in Nonmetropolitan America.

    Science.gov (United States)

    Beale, Calvin L.

    Population grew faster in nonmetro than in metro countries of the United States between 1970 and 1973. This trend reverses the previous pattern of inmigration to cities. Among the reasons for increases in rural areas and small towns are: (1) decentralization of manufacturing and other industry; (2) increased settlement of retired people; (3)…

  15. Population growth, urban expansion, and private forestry in western Oregon.

    Science.gov (United States)

    Jeffrey D. Kline; David L. Azuma; Ralph J. Alig

    2004-01-01

    Private forestlands in the United States face increasing pressures from growing populations, resulting in greater numbers of people living in closer proximity to forests. What often is called the "wildland/urban interface" is characterized by expansion of residential and other developed land uses onto forested landscapes in a manner that threatens forestlands...

  16. Population structure and growth of polydorid polychaetes that infest ...

    African Journals Online (AJOL)

    Polydorid polychaetes can infest cultured abalone thereby reducing productivity. In order to effectively control these pests, their reproductive biology must be understood. The population dynamics and reproduction of polydorids infesting abalone Haliotis midae from two farms in South Africa is described using a ...

  17. Separating intrinsic and environmental contributions to growth and their population consequences.

    Science.gov (United States)

    Shelton, Andrew O; Satterthwaite, William H; Beakes, Michael P; Munch, Stephan B; Sogard, Susan M; Mangel, Marc

    2013-06-01

    Among-individual heterogeneity in growth is a commonly observed phenomenon that has clear consequences for population and community dynamics yet has proved difficult to quantify in practice. In particular, observed among-individual variation in growth can be difficult to link to any given mechanism. Here, we develop a Bayesian state-space framework for modeling growth that bridges the complexity of bioenergetic models and the statistical simplicity of phenomenological growth models. The model allows for intrinsic individual variation in traits, a shared environment, process stochasticity, and measurement error. We apply the model to two populations of steelhead trout (Oncorhynchus mykiss) grown under common but temporally varying food conditions. Models allowing for individual variation match available data better than models that assume a single shared trait for all individuals. Estimated individual variation translated into a roughly twofold range in realized growth rates within populations. Comparisons between populations showed strong differences in trait means, trait variability, and responses to a shared environment. Together, individual- and population-level variation have substantial implications for variation in size and growth rates among and within populations. State-dependent life-history models predict that this variation can lead to differences in individual life-history expression, lifetime reproductive output, and population life-history diversity.

  18. Mating behavior, population growth, and the operational sex ratio: a periodic two-sex model approach.

    Science.gov (United States)

    Jenouvrier, Stéphanie; Caswell, Hal; Barbraud, Christophe; Weimerskirch, Henri

    2010-06-01

    We present a new approach to modeling two-sex populations, using periodic, nonlinear two-sex matrix models. The models project the population growth rate, the population structure, and any ratio of interest (e.g., operational sex ratio). The periodic formulation permits inclusion of highly seasonal behavioral events. A periodic product of the seasonal matrices describes annual population dynamics. The model is nonlinear because mating probability depends on the structure of the population. To study how the vital rates influence population growth rate, population structure, and operational sex ratio, we used sensitivity analysis of frequency-dependent nonlinear models. In nonlinear two-sex models the vital rates affect growth rate directly and also indirectly through effects on the population structure. The indirect effects can sometimes overwhelm the direct effects and are revealed only by nonlinear analysis. We find that the sensitivity of the population growth rate to female survival is negative for the emperor penguin, a species with highly seasonal breeding behavior. This result could not occur in linear models because changes in population structure have no effect on per capita reproduction. Our approach is applicable to ecological and evolutionary studies of any species in which males and females interact in a seasonal environment.

  19. Selection for life-history traits to maximize population growth in an invasive marine species

    DEFF Research Database (Denmark)

    Jaspers, Cornelia; Marty, Lise; Kiørboe, Thomas

    2018-01-01

    Species establishing outside their natural range, negatively impacting local ecosystems, are of increasing global concern. They often display life-history features characteristic for r-selected populations with fast growth and high reproduction rates to achieve positive population growth rates (r......) in invaded habitats. Here, we demonstrate substantially earlier maturation at a 2 orders of magnitude lower body mass at first reproduction in invasive compared to native populations of the comb jelly Mnemiopsis leidyi. Empirical results are corroborated by a theoretical model for competing life...... populations is an underappreciated determinant of invasiveness, acting as substrate upon which selection can act during the invasion process....

  20. Current and Future Dynamics of the Red-Cockaded Woodpecker Population Inhabiting the Savannah River National Environmental Research Park: Managing For Population Growth

    International Nuclear Information System (INIS)

    Walters, J.R.; Taylor, T.B.; Daniels, S.J.; Crowder, L.B.; Pridd, J.A.

    2001-01-01

    Research aimed to study the dynamics of the SRS population of Red-Cockaded woodpecker and compare to those of other populations to identify factors limiting population growth; recruitment clusters were evaluated to determine what properties of individual cavity trees, surrounding habitat and the surrounding landscape might limit occupancy through natural dispersal. A spatial simulation model was used to project expected dispersal rates and population growth under current conditions and compare those estimates to observed dispersal and population growth. Red cockaded woodpecker populations at SRS are stable considering size. Research reveals that closer placement of recruitment clusters to active territories would produce higher growth rates while decreasing management intensity

  1. Effects of sediment-spiked lufenuron on benthic macroinvertebrates in outdoor microcosms and single-species toxicity tests

    Energy Technology Data Exchange (ETDEWEB)

    Brock, T.C.M., E-mail: theo.brock@wur.nl [Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen (Netherlands); Bas, D.A. [Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam (Netherlands); Belgers, J.D.M. [Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen (Netherlands); Bibbe, L. [Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam (Netherlands); Boerwinkel, M-C.; Crum, S.J.H. [Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen (Netherlands); Diepens, N.J. [Department of Aquatic Ecology and Water Quality Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen (Netherlands); Kraak, M.H.S.; Vonk, J.A. [Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam (Netherlands); Roessink, I. [Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen (Netherlands)

    2016-08-15

    Highlights: • In outdoor microcosms constructed with lufenuron-spiked sediment we observed that this insecticide persistent in the sediment compartment. • Sediment exposure to lufenuron caused population-level declines (insects and crustaceans) and increases (mainly oligochaete worms) of benthic invertebrates. • The direct and indirect effects observed in the microcosms were supported by results of sediment-spiked single species tests with Chironomus riparius, Hyalella azteca and Lumbriculus variegatus. • The tier-1 effect assessment procedure for sediment organisms recommended by the European Food Safety Authority is protective for the treatment-related responses observed in the microcosm test. - Abstract: Sediment ecotoxicity studies were conducted with lufenuron to (i) complement the results of a water-spiked mesocosm experiment with this lipophilic benzoylurea insecticide, (ii) to explore the predictive value of laboratory single-species tests for population and community-level responses of benthic macroinvertebrates, and (iii) to calibrate the tier-1 effect assessment procedure for sediment organisms. For this purpose the concentration-response relationships for macroinvertebrates between sediment-spiked microcosms and those of 28-d sediment-spiked single-species toxicity tests with Chironomus riparius, Hyalella azteca and Lumbriculus variegatus were compared. Lufenuron persisted in the sediment of the microcosms. On average, 87.7% of the initial lufenuron concentration could still be detected in the sediment after 12 weeks. Overall, benthic insects and crustaceans showed treatment-related declines and oligochaetes treatment-related increases. The lowest population-level NOEC in the microcosms was 0.79 μg lufenuron/g organic carbon in dry sediment (μg a.s./g OC) for Tanytarsini, Chironomini and Dero sp. Multivariate analysis of the responses of benthic macroinvertebrates revealed a community-level NOEC of 0.79 μg a.s./g OC. The treatment

  2. From single-species advice to mixed-species management: taking the next step

    DEFF Research Database (Denmark)

    Vinther, Morten; Reeves, S.A.; Patterson, K.R.

    2004-01-01

    that accounts for mixed-fishery effects, but in the short term there is a need for approaches to resolve the conflicting management advice for different species within the same fishery, and to generate catch or effort advice that accounts for the mixed-species nature of the fishery. This paper documents...... a recent approach used to address these problems. The approach takes the single-species advice for each species in the fishery as a starting point, then attempts to resolve it into consistent catch or effort advice using fleet-disaggregated catch forecasts in combination with explicitly stated management...

  3. Addressing challenges in single species assessments via a simple state-space assessment model

    DEFF Research Database (Denmark)

    Nielsen, Anders

    Single-species and age-structured fish stock assessments still remains the main tool for managing fish stocks. A simple state-space assessment model is presented as an alternative to (semi) deterministic procedures and the full parametric statistical catch at age models. It offers a solution...... to some of the key challenges of these models. Compared to the deterministic procedures it solves a list of problems originating from falsely assuming that age classified catches are known without errors and allows quantification of uncertainties of estimated quantities of interest. Compared to full...

  4. [The relationships between population growth and environment: from doctrinal to empirical].

    Science.gov (United States)

    Tabutin, D; Thiltges, E

    1992-01-01

    This work provides a brief review of changing attitudes toward population growth, the environment, and economic development, and summarizes the major theoretical doctrines concerning the interrelations between rapid population growth and environmental damage and results of research on the topic. The general optimism about the prospects for progress in the Southern hemisphere of the 1950s and 1960s gave way to greater skepticism and recognition of problems in the 1970s. The creation of the UN Population Fund in 1969 and the UN Environmental Program in 1972 reflected increasing concern in the international community about demographic growth and environmental degradation in the south. Economic and social conditions appeared to worsen in the 1980s, with the recession and structural adjustment programs having a disproportionate impact on the most destitute. New integrating concepts and paradigms including that of sustainable development arose in this context of profound crisis in many Third World economics and societies. The most widely accepted position on the connection between population growth and environmental degradation since the late 1970s has been a nuanced neo-Malthusian approach which sees demographic pressure not as the direct cause of environmental problems, but as an aggravating factor. The slowing of population growth is viewed as 1 element in an overall strategy that also includes encouragement of development and elimination of poverty. The extreme positions that rapid population growth is the major cause of environmental degeneration or that population growth has little actual effect on the environment have been largely abandoned. The impact of population growth on the environment can be analyzed at the global, regional, or local level. On the global level, there is agreement that 2 major factors responsible for environmental deterioration are the model of economic development followed in the Northern countries and the poverty of much of the population

  5. Population growth and housing needs for Cameroon 1976-2001.

    Science.gov (United States)

    Bongsuiru, L S

    1983-01-01

    An estimate of housing needs in Cameroon is presented up to the year 2001. Data are for urban and rural areas and are from the 1976 census and other sources. The medium projections are for a total population in 2001 of 15 million persons, 42 percent of whom will be in urban areas. The substantial need for additional housing in Douala and Yaounde is noted. (summary in FRE)

  6. Noise-Induced Transitions in a Population Growth Model Based on Size-Dependent Carrying Capacity

    Directory of Open Access Journals (Sweden)

    Neeme Lumi

    2014-01-01

    Full Text Available The stochastic dynamics of a population growth model with size-dependent carrying capacity is considered. The effect of a fluctuating environment on population growth is modeled as a multiplicative dichotomous noise. At intermediate values of population size the deterministic counterpart of the model behaves similarly to the Von Foerster model for human population, but at small and very large values of population size substantial differences occur. In the stochastic case, an exact analytical solution for the stationary probability distribution is found. It is established that variation of noise correlation time can cause noise-induced transitions between three different states of the system characterized by qualitatively different behaviors of the probability distributions of the population size. Also, it is shown that, in some regions of the system parameters, variation of the amplitude of environmental fluctuations can induce single unidirectional abrupt transitions of the mean population size.

  7. Variability in winter climate and winter extremes reduces population growth of an alpine butterfly.

    Science.gov (United States)

    Roland, Jens; Matter, Stephen F

    2013-01-01

    We examined the long-term, 15-year pattern of population change in a network of 21 Rocky Mountain populations of Parnassius smintheus butterflies in response to climatic variation. We found that winter values of the broadscale climate variable, the Pacific Decadal Oscillation (PDO) index, were a strong predictor of annual population growth, much more so than were endogenous biotic factors related to population density. The relationship between PDO and population growth was nonlinear. Populations declined in years with extreme winter PDO values, when there were either extremely warm or extremely cold sea surface temperatures in the eastern Pacific relative to that in the western Pacific. Results suggest that more variable winters, and more frequent extremely cold or warm winters, will result in more frequent decline of these populations, a pattern exacerbated by the trend for increasingly variable winters seen over the past century.

  8. Population growth and income growth during the demographic transition: does a Malthusian model help explain their relationship?

    Science.gov (United States)

    Blanchet, D

    1990-01-01

    This paper examines the potential links between growth of income/head and population growth during demographic transition. In so doing, both malthusian and neo-Boserupian views are considered with a view to determining which of the 2 paradigms is most useful in explaining the current situation in developing countries. The relationship between demographic and economic progress in the Malthusian system when it is initiated by an exogenous technical progress is discussed. Attention is also called to the recent disappearance of a negative correlation between economic and demographic growth. Finally, the neo-Boseupian model is compared to the Malthusian view, and implications of the analysis as they relate to the desirability of population policies are presented.

  9. Growth and population dynamics of Thalassodendron ciliatum in a Kenyan back-reef lagoon

    NARCIS (Netherlands)

    Duarte, C.M.; Hemminga, M.A.; Marbà, N.

    1996-01-01

    The size, rhizome growth, and demography of a Thalassodendron ciliatum (Forssk.) den Hartog population in a back-reef lagoon (Chale lagoon, Kenya), was examined using techniques based on age determinations. The results obtained reveal that vertical growth of the T. ciliatum shoots is very fast,

  10. Social security reform and population ageing in a two-sector growth model

    NARCIS (Netherlands)

    Groezen, Bas van; Meijdam, L.; Verbon, H.

    2002-01-01

    This paper analyses the e¤ects of reducing unfunded social security and population ageing on economic growth and welfare, both for a small open economy and for a closed economy. The economy consists of a service sector and a commodity sector. Productivity growth only occurs in the latter sector

  11. Social Security Reform and Population Ageing in a Two-Sector Growth Model

    NARCIS (Netherlands)

    van Groezen, B.J.A.M.; Meijdam, A.C.; Verbon, H.A.A.

    2002-01-01

    This paper analyses the effects of reducing unfunded social security and population ageing on economic growth and welfare, both for a small open economy and for a closed economy.The economy consists of a service sector and a commodity sector.Productivity growth only occurs in the latter sector and

  12. Effects of sediment-spiked lufenuron on benthic macroinvertebrates in outdoor microcosms and single-species toxicity tests.

    Science.gov (United States)

    Brock, T C M; Bas, D A; Belgers, J D M; Bibbe, L; Boerwinkel, M-C; Crum, S J H; Diepens, N J; Kraak, M H S; Vonk, J A; Roessink, I

    2016-08-01

    Sediment ecotoxicity studies were conducted with lufenuron to (i) complement the results of a water-spiked mesocosm experiment with this lipophilic benzoylurea insecticide, (ii) to explore the predictive value of laboratory single-species tests for population and community-level responses of benthic macroinvertebrates, and (iii) to calibrate the tier-1 effect assessment procedure for sediment organisms. For this purpose the concentration-response relationships for macroinvertebrates between sediment-spiked microcosms and those of 28-d sediment-spiked single-species toxicity tests with Chironomus riparius, Hyalella azteca and Lumbriculus variegatus were compared. Lufenuron persisted in the sediment of the microcosms. On average, 87.7% of the initial lufenuron concentration could still be detected in the sediment after 12 weeks. Overall, benthic insects and crustaceans showed treatment-related declines and oligochaetes treatment-related increases. The lowest population-level NOEC in the microcosms was 0.79μg lufenuron/g organic carbon in dry sediment (μg a.s./g OC) for Tanytarsini, Chironomini and Dero sp. Multivariate analysis of the responses of benthic macroinvertebrates revealed a community-level NOEC of 0.79μg a.s./g OC. The treatment-related responses observed in the microcosms are in accordance with the results of the 28-d laboratory toxicity tests. These tests showed that the insect C. riparius and the crustacean H. azteca were approximately two orders of magnitude more sensitive than the oligochaete L. variegatus. In our laboratory tests, using field-collected sediment, the lowest 28-d EC10 (0.49μg a.s./g OC) was observed for C. riparius (endpoint survival), while for the standard OECD test with this species, using artificial sediment, a NOEC of 2.35μg a.s./g OC (endpoint emergence) is reported. In this particular case, the sediment tier-1 effect assessment using the chronic EC10 (field-collected sediment) or chronic NOEC (artificial sediment) of C

  13. Genetic Parameter Estimation in Seedstock Swine Population for Growth Performances

    Directory of Open Access Journals (Sweden)

    Jae Gwan Choi

    2013-04-01

    Full Text Available The objective of this study was to estimate genetic parameters that are to be used for across-herd genetic evaluations of seed stock pigs at GGP level. Performance data with pedigree information collected from swine breeder farms in Korea were provided by Korea Animal Improvement Association (AIAK. Performance data were composed of final body weights at test days and ultrasound measures of back fat thickness (BF, rib eye area (EMA and retail cut percentage (RCP. Breeds of swine tested were Landrace, Yorkshire and Duroc. Days to 90 kg body weight (DAYS90 were estimated with linear function of age and ADG calculated from body weights at test days. Ultrasound measures were taken with A-mode ultrasound scanners by trained technicians. Number of performance records after censoring outliers and keeping records pigs only born from year 2000 were of 78,068 Duroc pigs, 101,821 Landrace pigs and 281,421 Yorkshire pigs. Models included contemporary groups defined by the same herd and the same seasons of births of the same year, which was regarded as fixed along with the effect of sex for all traits and body weight at test day as a linear covariate for ultrasound measures. REML estimation was processed with REMLF90 program. Heritability estimates were 0.40, 0.32, 0.21 0.39 for DAYS90, ADG, BF, EMA, RCP, respectively for Duroc population. Respective heritability estimates for Landrace population were 0.43, 0.41, 0.22, and 0.43 and for Yorkshire population were 0.36, 0.38, 0.22, and 0.42. Genetic correlation coefficients of DAYS90 with BF, EMA, or RCP were estimated to be 0.00 to 0.09, −0.15 to −0.25, 0.22 to 0.28, respectively for three breeds populations. Genetic correlation coefficients estimated between BF and EMA was −0.33 to −0.39. Genetic correlation coefficient estimated between BF and RCP was high and negative (−0.78 to −0.85 but the environmental correlation coefficients between these two traits was medium and negative (near −0

  14. The growth of XXX females: population-based studies.

    Science.gov (United States)

    Ratcliffe, S G; Pan, H; McKie, M

    1994-01-01

    Longitudinal measurements of height, sitting height and leg length are compared between 11 XXX girls identified by cytogenetic screening, and 16 chromosomally normal controls from the same population using a nonparametric method. While height velocity did not differ between the two groups either during the pubertal or the mid-childhood spurts, leg length velocity was significantly increased during the mid-childhood spurt, between 4 and 9 years of age. A further contribution to the increased leg length came from the slower decline in leg length velocity at the end of the pubertal spurt. The possible mechanisms involved in these changes are discussed.

  15. Global water resources: vulnerability from climate change and population growth.

    Science.gov (United States)

    Vörösmarty, C J; Green, P; Salisbury, J; Lammers, R B

    2000-07-14

    The future adequacy of freshwater resources is difficult to assess, owing to a complex and rapidly changing geography of water supply and use. Numerical experiments combining climate model outputs, water budgets, and socioeconomic information along digitized river networks demonstrate that (i) a large proportion of the world's population is currently experiencing water stress and (ii) rising water demands greatly outweigh greenhouse warming in defining the state of global water systems to 2025. Consideration of direct human impacts on global water supply remains a poorly articulated but potentially important facet of the larger global change question.

  16. An interest-group theory of population growth.

    Science.gov (United States)

    Kimenyi, M S; Shughart, W F; Tollison, R D

    1988-10-01

    Conventional economic analyses of fertility overlook the impact of competition among various interest groups (racial, tribal, religious) in the political market for transfers of wealth. For example, a tribe or group may be motivated to increase its size in order to gain control of the society's instruments of wealth transfer. The model developed in this paper assumes that it is the size of an interest group that determines the extent of its influence on the legislature or a military government and that competition for transfers will be greatest in highly heterogeneous societies. Thus, it is hypothesized that, the more heterogeneous a given population, the higher will be that country's fertility rate. Variables included in the regression equations were: a heterogeneity index, per capita income, per capita expenditures on education as a percentage of per capita income, the female literacy rate, and the regression error term. The regression analyses of data from 130 countries for 1980 strongly suggested that the heterogeneity of a country's population is reflected in a higher birth or fertility rate. The income and literacy variables had a significant negative effect on the birth rate, while the educational expenditure variable had a negative but nonsignificant effect. These findings are consistent with Becker's economic analyses of fertility, but demonstrate the predictive value of the heterogeneity index. Since the characteristics that define heterogeneity--race, color, and tribal group--are generally fixed, the optimal strategy for interest groups to increase their relative wealth is to maximize group reproduction.

  17. The between-population genetic architecture of growth, maturation, and plasticity in Atlantic salmon.

    Science.gov (United States)

    Debes, Paul Vincent; Fraser, Dylan John; Yates, Matthew; Hutchings, Jeffrey A

    2014-04-01

    The between-population genetic architecture for growth and maturation has not been examined in detail for many animal species despite its central importance in understanding hybrid fitness. We studied the genetic architecture of population divergence in: (i) maturation probabilities at the same age; (ii) size at age and growth, while accounting for maturity status and sex; and (iii) growth plasticity in response to environmental factors, using divergent wild and domesticated Atlantic salmon (Salmo salar). Our work examined two populations and their multigenerational hybrids in a common experimental arrangement in which salinity and quantity of suspended sediments were manipulated to mimic naturally occurring environmental variation. Average specific growth rates across environments differed among crosses, maturity groups, and cross-by-maturity groups, but a growth-rate reduction in the presence of suspended sediments was equal for all groups. Our results revealed both additive and nonadditive outbreeding effects for size at age and for growth rates that differed with life stage, as well as the presence of different sex- and size-specific maturation probabilities between populations. The major implication of our work is that estimates of the genetic architecture of growth and maturation can be biased if one does not simultaneously account for temporal changes in growth and for different maturation probabilities between populations. Namely, these correlated traits interact differently within each population and between sexes and among generations, due to nonadditive effects and a level of independence in the genetic control for traits. Our results emphasize the challenges to investigating and predicting phenotypic changes resulting from between-population outbreeding.

  18. Population growth of Mexican free-tailed bats (Tadarida brasiliensis mexicana predates human agricultural activity

    Directory of Open Access Journals (Sweden)

    Cox Murray P

    2011-04-01

    Full Text Available Abstract Background Human activities, such as agriculture, hunting, and habitat modification, exert a significant effect on native species. Although many species have suffered population declines, increased population fragmentation, or even extinction in connection with these human impacts, others seem to have benefitted from human modification of their habitat. Here we examine whether population growth in an insectivorous bat (Tadarida brasiliensis mexicana can be attributed to the widespread expansion of agriculture in North America following European settlement. Colonies of T. b. mexicana are extremely large (~106 individuals and, in the modern era, major agricultural insect pests form an important component of their food resource. It is thus hypothesized that the growth of these insectivorous bat populations was coupled to the expansion of agricultural land use in North America over the last few centuries. Results We sequenced one haploid and one autosomal locus to determine the rate and time of onset of population growth in T. b. mexicana. Using an approximate Maximum Likelihood method, we have determined that T. b. mexicana populations began to grow ~220 kya from a relatively small ancestral effective population size before reaching the large effective population size observed today. Conclusions Our analyses reject the hypothesis that T. b. mexicana populations grew in connection with the expansion of human agriculture in North America, and instead suggest that this growth commenced long before the arrival of humans. As T. brasiliensis is a subtropical species, we hypothesize that the observed signals of population growth may instead reflect range expansions of ancestral bat populations from southern glacial refugia during the tail end of the Pleistocene.

  19. [Age structure and growth pattern of Polytrichum juniperum populations in a mire of Changbai Mountains].

    Science.gov (United States)

    Bu, Zhaojun; Yan, Yunfei; Dai, Dan; Wang, Xianwei

    2005-01-01

    In this paper, the age structure and growth pattern of two Polytrichum juniperum populations with and without sporophytes in Hani mire of Changbai Mountains were studied by 'innate annual marker' method. The ramets of both populations were composed of 6 age classes, and their quantity and biomass showed a declining age structure, which was more obvious in the sporophyte produced population. No significant difference of biomass was found (P > 0.05) between the two populations. The dry material accumulation of the ramets in both populations increased with aging, and showed similar patterns of linear function. The ramets mean height of sporophyte-produced population was 6.17% shorter (P < 0.05) than the another, because sporophyte production limited the height growth. The ramets mean height also increased with aging, and showed similar patterns of linear function. In non-sporophyte produced population, the variation coefficient of ramets height was only 2.44%, which indicated the significance of similar height for ramets survival. In sporophyte produced population, the variation coefficient of ramets height was 25.07%, while that of ramets biomass was 8.25%, suggesting the significance of similar biomass to the reproduction of population. The biomass of ramets had a significantly positive correlation with height in both populations (P < 0.001), and no allometric growth was showed.

  20. From demographic dividend to demographic burden: The impact of population ageing on economic growth in Europe

    NARCIS (Netherlands)

    van der Gaag, N.L.; de Beer, J.A.A.

    2015-01-01

    In the coming years, the share of the working-age population in the total population will start to decline in all countries of the European Union. All other things remaining equal, this so-called demographic burden will have a downward effect on economic growth. This paper examines whether the

  1. Growth and physiological responses to varied environments among populations of Pinus ponderosa

    Science.gov (United States)

    Jianwei Zhang; Bert M. Cregg

    2005-01-01

    We investigated population responses in physiology, morphology, and growth of mature Pinus ponderosa trees to an environmental gradient across Nebraska, USA. Ten populations from western Nebraska and eastern Wyoming were grown in three 26-year-old provenance tests from the warmest and wettest site in the east (Plattsmouth) to the intermediate site in...

  2. Studies of Health and Long-Term Care Expenditure Growth in Aging Populations

    NARCIS (Netherlands)

    C.A.M. de Meijer (Claudine)

    2012-01-01

    textabstractIn recent decades, elderly populations in most developed countries have increased considerably, both in absolute and relative terms. This growth of the elderly share of the population is mainly attributable to two demographic transitions: the (simultaneous) increase in longevity and

  3. Rapid population growth and fragile environments: the sub-Saharan African and south Asian experience.

    Science.gov (United States)

    Caldwell, J C; Caldwell, P

    1994-02-18

    Case studies of the world's two poorest regions, sub-Saharan Africa and South Asia, were used to illustrate the compromised standard of living of the poor and environmental damage due to continued rapid population growth. The conclusion was that the livelihoods of the poor should not be endangered for preserving the living standards of richer people. Nations must not ignore the challenges of reducing population growth as fast as can be achieved. The transitional period over the next 50 years is the main concern, because population growth rates will be slowing. Rural population growth is expected to decline from 60% of total population growth in South Asia to 7% between 2000 and 2025; similarly the decline in sub-Saharan Africa would be from 50% to 15%. Over the past 30 years, food production in South Asia has kept pace with population growth. Sub-Saharan Africa has adopted food importation to meet demand. African problems are a low resource base, faster population growth, and the fact that governments and individuals are too poor to maintain soil fertility. Long-term studies of how much soil depletion will occur are not available for these regions, and local area studies are not as pessimistic. Transition policies are needed to put "people first in terms of engineered or directed population and ecological change." The six main issues are the following: 1) the Brundtland Commission appropriately identified poverty as the main cause and effect of environmental degradation because of the threat to survival; 2) the verdict is still out about whether food production will keep pace with population growth through economic growth and investment in agriculture; 3) empirical research is needed to examine local social and regulatory institutions and the possibility of reinforcing these mechanisms rather than instituting central controls; 4) central coercion or modernizing economic policies can destroy local level controls; 5) famine is a complex ecological phenomenon and the

  4. Generation time, net reproductive rate, and growth in stage-age-structured populations

    DEFF Research Database (Denmark)

    Steiner, Uli; Tuljapurkar, Shripad; Coulson, Tim

    2014-01-01

    to age-structured populations. Here we generalize this result to populations structured by stage and age by providing a new, unique measure of reproductive timing (Tc) that, along with net reproductive rate (R0), has a direct mathematical relationship to and approximates growth rate (r). We use simple...... examples to show how reproductive timing Tc and level R0 are shaped by stage dynamics (individual trait changes), selection on the trait, and parent-offspring phenotypic correlation. We also show how population structure can affect dispersion in reproduction among ages and stages. These macroscopic...... features of the life history determine population growth rate r and reveal a complex interplay of trait dynamics, timing, and level of reproduction. Our results contribute to a new framework of population and evolutionary dynamics in stage-and-age-structured populations....

  5. A new ODE tumor growth modeling based on tumor population dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Oroji, Amin; Omar, Mohd bin [Institute of Mathematical Sciences, Faculty of Science University of Malaya, 50603 Kuala Lumpur, Malaysia amin.oroji@siswa.um.edu.my, mohd@um.edu.my (Malaysia); Yarahmadian, Shantia [Mathematics Department Mississippi State University, USA Syarahmadian@math.msstate.edu (United States)

    2015-10-22

    In this paper a new mathematical model for the population of tumor growth treated by radiation is proposed. The cells dynamics population in each state and the dynamics of whole tumor population are studied. Furthermore, a new definition of tumor lifespan is presented. Finally, the effects of two main parameters, treatment parameter (q), and repair mechanism parameter (r) on tumor lifespan are probed, and it is showed that the change in treatment parameter (q) highly affects the tumor lifespan.

  6. A new ODE tumor growth modeling based on tumor population dynamics

    International Nuclear Information System (INIS)

    Oroji, Amin; Omar, Mohd bin; Yarahmadian, Shantia

    2015-01-01

    In this paper a new mathematical model for the population of tumor growth treated by radiation is proposed. The cells dynamics population in each state and the dynamics of whole tumor population are studied. Furthermore, a new definition of tumor lifespan is presented. Finally, the effects of two main parameters, treatment parameter (q), and repair mechanism parameter (r) on tumor lifespan are probed, and it is showed that the change in treatment parameter (q) highly affects the tumor lifespan

  7. A probabilistic cellular automata model for the dynamics of a population driven by logistic growth and weak Allee effect

    Science.gov (United States)

    Mendonça, J. R. G.

    2018-04-01

    We propose and investigate a one-parameter probabilistic mixture of one-dimensional elementary cellular automata under the guise of a model for the dynamics of a single-species unstructured population with nonoverlapping generations in which individuals have smaller probability of reproducing and surviving in a crowded neighbourhood but also suffer from isolation and dispersal. Remarkably, the first-order mean field approximation to the dynamics of the model yields a cubic map containing terms representing both logistic and weak Allee effects. The model has a single absorbing state devoid of individuals, but depending on the reproduction and survival probabilities can achieve a stable population. We determine the critical probability separating these two phases and find that the phase transition between them is in the directed percolation universality class of critical behaviour.

  8. The ocean blues. Navigating the course of population growth.

    Science.gov (United States)

    Sarkar, D

    1996-01-01

    Oceans and their role in environmental balance are discussed in this article. Coastal waters within 200 miles from land are identified as providing over half the ocean's total biological productivity and supply of nearly all of the world's fish catch. Almost 3.6 billion people live in coastal areas or within 90 miles of coastal waters, which accounts for about 66% of world population. Coastal land areas account for about 8% of the earth's total land area. 8.3 billion people are expected by 2025 to live in coastal areas. 9 of the 10 largest cities in the world are located on coasts. 7 of the 10 largest cities in the US are coastal cities (54% of the US population or 142 million people). Almost all of the marine pollution is derived from land-based sources, such as sewage, nutrients, sediments, litter, and plastics. Mangroves in coastal waters have been reduced by about 50% to about 90,000 sq. miles worldwide. Global consumption of fish is responsible for depleting fish supplies and the loss of mangroves due to aquaculture of shrimp or other seafood. The US National Fisheries Service is cited for its report that 67 of the 156 fish stocks are overexploited. About 1 billion people, mostly in developing countries, rely on fish as their main food source. If imbalances in demand and supply continue, the rising price of fish and seafood will threaten the lives of about 1 billion or more people. Numerous international and national actions have been taken in order to protect supplies and reduce pollution. Sound resource management practices need to be instituted. Small and large fisheries can begin by reducing the 27 million tons of unintentional fish captures and by converting 29 million tons of fish used for animal feed into food for human consumption. Management of US coastal lands in most coastal states, with the exception of California and Rhode Island, is weak. Maryland has adopted a community-level approach for management of the Chesapeake Bay. Other environmental

  9. Influence of Cell-Cell Interactions on the Population Growth Rate in a Tumor

    Science.gov (United States)

    Chen, Yong

    2017-12-01

    The understanding of the macroscopic phenomenological models of the population growth at a microscopic level is important to predict the population behaviors emerged from the interactions between the individuals. In this work, we consider the influence of the population growth rate R on the cell-cell interaction in a tumor system and show that, in most cases especially small proliferative probabilities, the regulative role of the interaction will be strengthened with the decline of the intrinsic proliferative probabilities. For the high replication rates of an individual and the cooperative interactions, the proliferative probability almost has no effect. We compute the dependences of R on the interactions between the cells under the approximation of the nearest neighbor in the rim of an avascular tumor. Our results are helpful to qualitatively understand the influence of the interactions between the individuals on the growth rate in population systems. Supported by the National Natural Science Foundation of China under Grant Nos. 11675008 and 21434001

  10. Population growth and environment as a self-organizing system

    Directory of Open Access Journals (Sweden)

    Peter M. Allen

    1999-01-01

    Full Text Available Over recent years a new understanding of complex systems, and their dynamics and evolution has emerged, and these have been shown to provide a new basis for models of the changing patterns of population and economic activities that shape the landscape. In this paper we make clear the necessarily partial description that any particular model must provide, and show the importance of a multidisciplinary, holistic understanding, linking any particular model to the co-evolution of its environment. In addition, we show how evolutionary processes link the microscopic level of molecules through successive scales of structure and organization ultimately to the biosphere itself, to issues of climatic change, of biomes at the continental scale and atmospheric and oceanic circulation patterns. Some very recent results will be shown which demonstrate that the world climate has already been modified considerably by human activities, particularly agriculture, underlining the vital need to understand better the on-going interaction between human activities and the biosphere.

  11. [Is it necessary to control the population growth of national minorities].

    Science.gov (United States)

    Tian, X Y

    1981-02-01

    In the process of Socialist construction and modernization, the development of the population of national minorities deserves our attention because it is directly related to the economic and cultural development in the areas inhabited by such national minorities, and it has a great impact on the welfare and future of those people. Moreover, the population growth of the minorities is a key factor in the national population control strategy. A rapid population growth among the minorities has caused serious problems in distribution of farm land and food supply, low personal income, a rise in the unemployment rate, and a rise in the illiteracy rate. This has prevented a rise in the living standard among the minority population. In order to prevent and solve population problems among the minorities, we must take appropriate measures according to local conditions to control population increases. Through popularization of education, population growth may be put under control. For those people who volunteer to practice family planning, the government should provide all kinds of assistance. At the same time, an effort is needed to introduce the necessity of improving birth quality, to popularize new methods of child birth, and to develop health and medical care for the general public, so that the quality of the minority population may be gradually improved.

  12. [It is imperative to control population growth in a planned way].

    Science.gov (United States)

    1980-02-15

    To facilitate modernization and prosperity of the Chinese nation, it is important that population growth be curbed in a planned way so as to correspond to the development of the national economy, and to stabilize the population at about 1.2 billion people by the year 2000. The 1-child policy should be strongly advocated. Currently, young people under 21 years old constitute 50% of the total population; 20 million of them are expected to get married and bear children each year before the end of this century, contributing to a high birth rate if allowed to remain unchecked. The 1-child policy is the best method for reducing birth rate and ensuring zero population growth in the year 2000. Because of strong leadership by authorities over family planning, the rate of natural population growth in this country has been lowered at a fairly rapid pace from 23.4/1000 in 1971 to the current 12/1000. Population growth rate in many provinces and municipalities is continually declining, and the masses have raised their consciousness of practicing family planning. Evidence has strongly indicated that broad masses of people have indeed fully understood the close relationship between childbirth, the realization of the 4 modernizations, and happy life for many generations to come. Because of the volume of work involved in enforcing family planning policies, authorities at all levels should strengthen their leadership and place high priority on family planning and population growth control. Emphasis should also be given on various methods to vigorously publicize the relations between family planning and the realization of the 4 modernizations, to publicize the country's goals and measures to control population growth, to continuously eliminate the decadent concept of the superiority of the male child, and to publicize the benefits of a 1-child family. Particular attention should also be given to 800 million people living in rural areas.

  13. Physical growth of the shuar: Height, Weight, and BMI references for an indigenous amazonian population.

    Science.gov (United States)

    Urlacher, Samuel S; Blackwell, Aaron D; Liebert, Melissa A; Madimenos, Felicia C; Cepon-Robins, Tara J; Gildner, Theresa E; Snodgrass, J Josh; Sugiyama, Lawrence S

    2016-01-01

    Information concerning physical growth among small-scale populations remains limited, yet such data are critical to local health efforts and to foster basic understandings of human life history and variation in childhood development. Using a large dataset and robust modeling methods, this study aims to describe growth from birth to adulthood among the indigenous Shuar of Amazonian Ecuador. Mixed-longitudinal measures of height, weight, and body mass index (BMI) were collected from Shuar participants (n = 2,463; age: 0-29 years). Centile growth curves and tables were created for each anthropometric variable of interest using Generalized Additive Models for Location, Scale, and Shape (GAMLSS). Pseudo-velocity and Lambda-Mu-Sigma curves were generated to further investigate Shuar patterns of growth and to facilitate comparison with United States Center for Disease Control and Prevention and multinational World Health Organization growth references. The Shuar are small throughout life and exhibit complex patterns of growth that differ substantially from those of international references. Similar to other Amazonians, Shuar growth in weight compares more favorably to references than growth in height, resulting in BMI curves that approximate international medians. Several additional characteristics of Shuar development are noteworthy, including large observed variation in body size early in life, significant infant growth faltering, extended male growth into adulthood, and a markedly early female pubertal growth spurt in height. Phenotypic plasticity and genetic selection in response to local environmental factors may explain many of these patterns. Providing a detailed reference of growth for the Shuar and other Amazonian populations, this study possesses direct clinical application and affords valuable insight into childhood health and the ecology of human growth. © 2015 Wiley Periodicals, Inc.

  14. A spatial analysis of patterns of growth and concentration of population based on homogeneous population censuses: Spain (1877-2001

    Directory of Open Access Journals (Sweden)

    Xavier Franch Auladell

    2013-01-01

    Full Text Available This work constitutes a contribution to the analysis of long term patterns of population concentration applied to the case of Spain. The proposed methodology is based on the homogenisation of both data and administrative units which takes the municipal structure of the 2001 census as its base reference. This work seeks to show how applying spatial analysis techniques to this type of homogeneous data series allows us to make more detailed studies of population patterns within a given territory. The most important conclusions that we reached was that, in Spain, sustained population growth has followed a spatial pattern that has become increasingly consolidated over time. The tendencies observed have produced an uneven distribution of population within the national territory marked by the existence of a series of well-defined, and often very localised, areas that spread beyond the limits of the official administrative boundaries.

  15. Development of paradigms for the dynamics of structured populations

    Energy Technology Data Exchange (ETDEWEB)

    1994-10-01

    This is a technical progress report on the dynamics of predator-prey systems in a patchy environment. A new phenomenon that might contribute to outbreaks in systems of discrete patches has been determined using a discrete time model with both spatial and age structure. A model for a single species in a patchy environment with migration, local population growth and disasters with in patches has been formulated and a brief description is included.

  16. Current demographics suggest future energy supplies will be inadequate to slow human population growth.

    Directory of Open Access Journals (Sweden)

    John P DeLong

    Full Text Available Influential demographic projections suggest that the global human population will stabilize at about 9-10 billion people by mid-century. These projections rest on two fundamental assumptions. The first is that the energy needed to fuel development and the associated decline in fertility will keep pace with energy demand far into the future. The second is that the demographic transition is irreversible such that once countries start down the path to lower fertility they cannot reverse to higher fertility. Both of these assumptions are problematic and may have an effect on population projections. Here we examine these assumptions explicitly. Specifically, given the theoretical and empirical relation between energy-use and population growth rates, we ask how the availability of energy is likely to affect population growth through 2050. Using a cross-country data set, we show that human population growth rates are negatively related to per-capita energy consumption, with zero growth occurring at ∼13 kW, suggesting that the global human population will stop growing only if individuals have access to this amount of power. Further, we find that current projected future energy supply rates are far below the supply needed to fuel a global demographic transition to zero growth, suggesting that the predicted leveling-off of the global population by mid-century is unlikely to occur, in the absence of a transition to an alternative energy source. Direct consideration of the energetic constraints underlying the demographic transition results in a qualitatively different population projection than produced when the energetic constraints are ignored. We suggest that energetic constraints be incorporated into future population projections.

  17. Population growth and social change: a note on rural society.

    Science.gov (United States)

    Barnabas, A P

    1974-01-01

    Changing social conditons, particularly in rural areas, often create a feeling of normlessness. For such major changes as family limitation to be accepted in rural India, those involved must understand the total social change which will be necessary. In rural areas today the desire for motherhood is a matter of being accepted. A barren woman suffers social ostracism; folk tales tell of even animals refusing to eat a meal prepared by a barren woman. A women with a large family is particularly respected, especially if they are well provided for. The other reasons given for having large numbers of children are family survival, care in old age, increase in family income, to get more share in the property, to follow the community pattern, and to make the home happier. There is a rationale for most of these. High infant and child mortality account for the family survival, The only security the parents have is the children. More children increase the family share in a joint-family land-holding. Raising the age at marriage for girls has often been suggested as a population control measure, but what is the girl to do until 19? Rural parents do not feel their obligations to their daughter have been discharged until she is married and it is the parents who are blamed if no arrangments have been made. The idea of her becoming educated is not socially acceptable and rural boys are reluctant to marry educated girls. India's values pertaining to divorce, widow remarriage, and abortion are already undergoing change. Migration to the cities is bringing about change. Looking to the cities may bring about modernization, but the fact that the young men are the ones moving away is leading a lack of leadership in the villages. To bring about the social conditions favorable to modernization agriculture should be modernized, reducing the need for labor; factories should be built in rural areas to take up this slack in agricultural employment, and perhaps it would become acceptable for

  18. Comparison of individual-based modeling and population approaches for prediction of foodborne pathogens growth.

    Science.gov (United States)

    Augustin, Jean-Christophe; Ferrier, Rachel; Hezard, Bernard; Lintz, Adrienne; Stahl, Valérie

    2015-02-01

    Individual-based modeling (IBM) approach combined with the microenvironment modeling of vacuum-packed cold-smoked salmon was more effective to describe the variability of the growth of a few Listeria monocytogenes cells contaminating irradiated salmon slices than the traditional population models. The IBM approach was particularly relevant to predict the absence of growth in 25% (5 among 20) of artificially contaminated cold-smoked salmon samples stored at 8 °C. These results confirmed similar observations obtained with smear soft cheese (Ferrier et al., 2013). These two different food models were used to compare the IBM/microscale and population/macroscale modeling approaches in more global exposure and risk assessment frameworks taking into account the variability and/or the uncertainty of the factors influencing the growth of L. monocytogenes. We observed that the traditional population models significantly overestimate exposure and risk estimates in comparison to IBM approach when contamination of foods occurs with a low number of cells (population model were characterized by a great uncertainty. The overestimation was mainly linked to the ability of IBM to predict no growth situations rather than the consideration of microscale environment. On the other hand, when the aim of quantitative risk assessment studies is only to assess the relative impact of changes in control measures affecting the growth of foodborne bacteria, the two modeling approach gave similar results and the simplest population approach was suitable. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Impact of Anthropogenic Noise on Aquatic Animals: From Single Species to Community-Level Effects.

    Science.gov (United States)

    Sabet, Saeed Shafiei; Neo, Yik Yaw; Slabbekoorn, Hans

    2016-01-01

    Anthropogenic noise underwater is on the rise and may affect aquatic animals of marine and freshwater ecosystems. Many recent studies concern some sort of impact assessment of a single species. Few studies addressed the noise impact on species interactions underwater, whereas there are some studies that address community-level impact but only on land in air. Key processes such as predator-prey or competitor interactions may be affected by the masking of auditory cues, noise-related disturbance, or attentional interference. Noise-associated changes in these interactions can cause shifts in species abundance and modify communities, leading to fundamental ecosystem changes. To gain further insight into the mechanism and generality of earlier findings, we investigated the impact on both a predator and a prey species in captivity, zebrafish (Danio rerio) preying on waterfleas (Daphnia magna).

  20. Coupled dynamics of energy budget and population growth of tilapia in response to pulsed waterborne copper.

    Science.gov (United States)

    Chen, Wei-Yu; Lin, Chia-Jung; Ju, Yun-Ru; Tsai, Jeng-Wei; Liao, Chung-Min

    2012-11-01

    The impact of environmentally pulsed metal exposure on population dynamics of aquatic organisms remains poorly understood and highly unpredictable. The purpose of our study was to link a dynamic energy budget model to a toxicokinetic/toxicodynamic (TK/TD). We used the model to investigate tilapia population dynamics in response to pulsed waterborne copper (Cu) assessed with available empirical data. We mechanistically linked the acute and chronic bioassays of pulsed waterborne Cu at the scale of individuals to tilapia populations to capture the interaction between environment and population growth and reproduction. A three-stage matrix population model of larva-juvenile-adult was used to project offspring production through two generations. The estimated median population growth rate (λ) decreased from 1.0419 to 0.9991 under pulsed Cu activities ranging from 1.6 to 2.0 μg L(-1). Our results revealed that the influence on λ was predominately due to changes in the adult survival and larval survival and growth functions. We found that pulsed timing has potential impacts on physiological responses and population abundance. Our study indicated that increasing time intervals between first and second pulses decreased mortality and growth inhibition of tilapia populations, indicating that during long pulsed intervals tilapia may have enough time to recover. Our study concluded that the bioenergetics-based matrix population methodology could be employed in a life-cycle toxicity assessment framework to explore the effect of stage-specific mode-of-actions in population response to pulsed contaminants.

  1. On the relationship between population growth and social and economic development.

    Science.gov (United States)

    Xu, D

    1983-01-01

    China's population has grown rapidly since 1949, reaching a size of 1,008,170,000 by 1982. Rapid population growth has been encouraged by a high birth rate coupled with low mortality, traditional preference for sons, and the incorrect assumption that man is only a producer and not a consumer. Rapid population growth directly decreases economic development while producing a rapidly increasing labor force requiring an increase in the number of jobs available. Population growth has already reduced arable land from 3 MN in 1949 to 1.5 MN at present and can also cause sanitation and pollution problems. Only by adopting family plnning and the 1 child family can China gradually slow population growth to correspond with economic development; then the state will be able to improve health care and education and, therefore, population quality. China's population policy is not one of NeoMalthusianism, which advocates birth control and late marriage, and assumes the existence of a capitalist system and does not apply to communist systems. Malthus may have attempted to absolve the nourgeoisie from all blame by aiming his preaching against blind reproduction at the poor; he thought that overpopulation would be reduced by pestilence, war, and famine. Protecting capitalism motivated Malthus and other capitalists, but the Chinese want to promote economic development. Marx has refuted Malthus' views on population. While Chinese population policy and NeoMalthusianism agree on advocating birth control and late marriage, their underlying philosophies are different. The author supports laws and policies on fertility and family planning, and feels that population scientists must be involved in all aspects--study, propaganda, and education--relating to family planning.

  2. Influence of Plant Population and Nitrogen-Fertilizer at Various Levels on Growth and Growth Efficiency of Maize

    Directory of Open Access Journals (Sweden)

    M. I. Tajul

    2013-01-01

    Full Text Available Field experiments were conducted to evaluate plant population and N-fertilizer effects on yield and yield components of maize (Zea mays L.. Three levels of plant populations (53000, 66000, and 800000 plants ha−1 corresponding to spacings of 75 × 25, 60 × 25, and 50 × 25 cm and 4 doses of N (100, 140, 180, and 220 kg ha−1 were the treatment variables. Results revealed that plant growth, light interception (LI, yield attributes, and grain yield varied significantly due to the variations in population density and N-rates. Crop growth rate (CGR was the highest with the population of 80,000 ha−1 receiving 220 kg N ha−1, while relative growth rate (RGR showed an opposite trend of CGR. Light absorption was maximum when most of densely populated plant received the highest amount of N (220 kg N ha−1. Response of soil-plant-analysis development (SPAD value as well as N-content to N-rates was found significant. Plant height was the maximum at the lowest plant density with the highest amount of N. Plants that received 180 kg N ha−1 with 80,000 plants ha−1 had larger foliage, greater SPAD value, and higher amount of grains cob−1 that contributed to the maximum yield (5.03 t ha−1 and the maximum harvest index (HI compared to the plants in other treatments.

  3. On the growth of primary industry and population of China’s counties

    Science.gov (United States)

    Xie, Wen-Jie; Gu, Gao-Feng; Zhou, Wei-Xing

    2010-09-01

    The growth dynamics of complex organizations have attracted much interest of econophysicists and sociophysicists in recent years. However, most of the studies are done for developed countries. We investigate the growth dynamics of the primary industry and the population of 2079 counties in mainland China using the data from the China County Statistical Yearbooks from 2000 to 2006. We find that the annual growth rates are distributed according to Student’s t distribution with the tail exponent less than 2. We find power-law relationships between the sample standard deviation of the growth rates and the initial size. The scaling exponent is less than 0.5 for the primary industry and close to 0.5 for the population.

  4. Total growth and migratory population growth for Spain in the Mediterranean

    Directory of Open Access Journals (Sweden)

    Graciela Sarrible

    2016-10-01

    Full Text Available Within the context of western Europe, both natural and migrant growth factors have varied in recent years, especially in Mediterranean countries. Migrations in this area have similar characteristics, such as the rising number of registered female migrant workers or the place of origin of some of the immigrant groups. In the case of Spain, it is interesting to note that the main influx has been due to the return of Spanish immigrants in recent years, although this trend is declining. International migrant movements are not a continuation of migration to other European countries and should be specifically studied.

  5. [A brief discussion on the effect of religion and feudal superstitions on China's population growth].

    Science.gov (United States)

    Chen, G

    1983-05-29

    According to Marxism, population development is subject to the determination of production means under certain social and historical conditions, but it is also influenced by ideology, religions, and other factors. China is a country with numerous religions and traditional superstitions. Their impact on China's population growth cannot be underestimated. All religions and feudal superstitions have a role in the increase of the population, and they oppose birth control and abortion. Similarly, traditional feudal concepts of having more children for good fortune, ancestral worship, and filial piety also encouraged early marriage and having more children, and they have contributed to population growth. On the contrary, "individualism" practiced by Buddhist monks and nuns, the "sacred war" believed by Islamic people, and the offering of human sacrifices by many primitive religions, and the murdering of baby twins have served to reduce the population. Most of the religions and feudal superstitions are in favor of increasing the population. The popularity of Buddhism in the past was caused by an oversupply of the labor force. Many farmers became Buddhist monks as a way to earn a living. Since liberation, unhealthy religions and feudal superstitions have been prohibited but their everlasting infulence upon the people cannot be ignored. Uncontrolled population growth is harmful to the nation's economy and improvement of people's livelihood. In family planning work, attention should also be given to the prevention of interference from religions and feudal superstitions in people's ideology.

  6. Age structure and growth of wild brown trout in relation to population density and habitat quality

    OpenAIRE

    Závorka, Libor

    2015-01-01

    Brown trout Salmo trutta L. is a fish species with high socio-economic value, which is favourable among anglers and a successful invader worldwide. The aim of this thesis is to explore environmental factors affecting body growth and survival of brown trout with emphasis on density dependent selection in juvenile life stages. This thesis is specifically focused on: (1) effect of population density on growth and survival with respect to a dynamic of a local group of individuals (papers I and II...

  7. Respective impact of climate and fisheries on the growth of an albatross population.

    Science.gov (United States)

    Rolland, V; Nevoux, M; Barbraud, C; Weimerskirch, H

    2009-07-01

    Climate and human activities such as fisheries impact many animal species. However, the demographic processes through which the population vital rates are affected, and the sensitivity of their growth rates, are poorly understood. The Black-browed Albatross, Thalassarche melanophrys, is a long-lived threatened seabird species. Previous studies have shown that the adult survival and breeding success of the population breeding at Kerguelen are affected by sea surface temperature anomalies (SSTA) during both the breeding and the nonbreeding season, and by tuna long-lining in Tasmanian waters through bycatch mortality. Here, using long-term demographic data from a Black-browed Albatross colony monitored for 26 years at Kerguelen, we estimate all demographic parameters from early to adult stages of the life cycle in order to build a fully parameterized population model and predict population growth rates under several scenarios of climate and fishing effort. The observed population growth rate (1.003) indicates that the population was stable or slightly increasing, and our population model gives a close estimate of 1.008. Population growth rate is more sensitive to survival of experienced breeders and accordingly to a change in SSTA during incubation and to tuna long-lining effort (both affecting survival of experienced breeders) than to other demographic parameters/environmental covariates. The population stability results from multiple factors and complex relationships between demographic parameters and environmental conditions, and therefore population equilibrium is precarious. If fishing effort remains stable at its current level and positive SSTA increase, or inversely if fishing effort decreases and SSTA remain similar to present values, then the population would increase. However, if fishing effort increases by 20% (i.e., to 40 million hooks) on the wintering grounds, without any change in SSTA, then the population would decrease at 0.9% per year. If fishing

  8. Exon 3-deleted and full-length growth hormone receptor polymorphism frequencies in an Iranian population

    OpenAIRE

    Palizban, A.A.; Radmansorry, M.; Bozorgzad, M.

    2014-01-01

    The functional role of the exon 3 growth hormone receptor (d3GHR) polymorphism in human and its distributions in different populations is not clearly understood. The presence of full length growth hormone (flGHR) is the most important in metabolic risk factors. The aim of this study was to define the frequency distribution of d3GHR/full-length GHR in an Iranian population. The presence of the d3GHR polymorphism in healthy volunteers blood DNA (n=80, male=30 and female=50) was assessed by PCR ...

  9. The impact of population change on the growth of mega-cities.

    Science.gov (United States)

    Guest, P

    1994-03-01

    The population dynamics of population growth in mega-cities and the contributions of migration to urban growth are described. The policy implications are identified as the need for a continued emphasis on fertility declines, because reductions will have a beneficial effect on reducing the pace of growth of mega-cities. The short-term goal of policy should be to provide urban contraceptive services to female migrants, who should be targeted specifically as a special group. Natural increase will be the main source of growth of mega-cities, and women who migrated during the 1990s will be a part of that natural increase. Reductions in population growth will make it easier for governments to provide services and to manage the large population size in mega-cities, which will continue to exist as long as economic activities are centralized and economic development promotes urbanization and spatial concentration. The emergence of mega-cities with populations of many millions has been a recent and increasing phenomena. The largest cities in 1980 were Tokyo with 16.9 million followed by New York City with 15.6 million. By 1990, the largest mega-cities were Mexico City with 20.2 million, Tokyo with 18.1 million, Sao Paulo with 17.4 million, and New York with 16.2 million. By the year 2000, the expectation is that Mexico City will have 25.6 million, Sao Paulo 22.1 million, Tokyo 19.0 million, Shanghai 17.0 million, and New York 16.8 million. The rankings will change, but the pattern clearly reflects the growth of mega-cities in developing countries. The age structure of urban populations is conducive to population growth. The main component of urban growth in Asia has been migration. Age structure changes have affected migration and will continue to affect fertility in mega-cities. Mega-cities will attract a young population because of the tourist and personnel services sectors which employ large numbers of young people, because of the demand for educated workers who tend to

  10. Role of prey and intraspecific density dependence on the population growth of an avian top predator

    Science.gov (United States)

    Fernandez-de-Simon, Javier; Díaz-Ruiz, Francisco; Cirilli, Francesca; Tortosa, Francisco S.; Villafuerte, Rafael; Ferreras, Pablo

    2014-10-01

    Exploring predator-prey systems in diverse ecosystems increases our knowledge about ecological processes. Predator population growth may be positive when conspecific density is low but predators also need areas with prey availability, associated with competition, which increases the risk of suffering losses but stabilises populations. We studied relationships between European rabbits Oryctolagus cuniculus (prey) and adult eagle owls Bubo bubo (predators) in south-western Europe. We assessed models explaining the predator population growth and stability. We estimated the abundance of rabbits and adult eagle owls during three years in eight localities of central-southern Spain. We explored models including rabbit and adult eagle owl abundance, accounting for yearly variations and including the locality as a random variable. We found that population growth of adult eagle owls was positive in situations with low conspecific abundance and tended to be negative but approaching equilibrium in situations of higher conspecific abundance. Population growth was also positively related to previous summer rabbit density when taking into account eagle owl conspecific abundance, possibly indicating that rabbits may support recruitment. Furthermore, abundance stability of adult eagle owls was positively related to previous winter-spring rabbit density, which could suggest predator population stabilisation through quick territory occupation in high-quality areas. These results exemplify the trade-off between prey availability and abundance of adult predators related to population growth and abundance stability in the eagle owl-rabbit system in south-western Europe. Despite rabbits have greatly declined during the last decades and eagle owls locally specialise on them, eagle owls currently have a favourable conservation status. As eagle owls are the only nocturnal raptor with such dependence on rabbits, this could point out that predators may overcome prey decreases in areas with

  11. Causes of mortality in California sea otters during periods of population growth and decline

    Science.gov (United States)

    Estes, J.A.; Hatfield, B.B.; Ralls, K.; Ames, J.

    2003-01-01

    Elevated mortality appears to be the main reason for both sluggish growth and periods of decline in the threatened California sea otter population. We assessed causes of mortality from salvage records of 3,105 beach-cast carcasses recovered from 1968 through 1999, contrasting two periods of growth with two periods of decline. Overall, an estimated 40%-60% of the deaths were not recovered and 70% of the recovered carcasses died from unknown causes. Nonetheless, several common patterns were evident in the salvage records during the periods of population decline. These included greater percentages of (1) prime age animals (3-10 yr), (2) carcasses killed by great white shark attacks, (3) carcasses recovered in spring and summer, and (4) carcasses for which the cause of death was unknown. Neither sex composition nor the proportion of carcasses dying of infectious disease varied consistently between periods of population increase and decline. The population decline from 1976 to 1984 was likely due to incidental mortality in a set-net fishery, and the decline from 1995 to 1999 may be related to a developing live-fish fishery. Long-term trends unrelated to periods of growth and decline included a decrease in per capita pup production and mass/length ratios of adult carcasses over the 31-yr study. The generally high proportion of deaths from infectious disease suggests that this factor has contributed to the chronically sluggish growth rate of the California sea otter population.

  12. Traveling bands for the Keller-Segel model with population growth.

    Science.gov (United States)

    Ai, Shangbing; Wang, Zhian

    2015-08-01

    This paper is concerned with the existence of the traveling bands to the Keller-Segel model with cell population growth in the form of a chemical uptake kinetics. We find that when the cell growth is considered, the profile of traveling bands, the minimum wave speed and the range of the chemical consumption rate for the existence of traveling wave solutions will change. Our results reveal that collective interaction of cell growth and chemical consumption rate plays an essential role in the generation of traveling bands. The research in the paper provides new insights into the mechanisms underlying the chemotactic pattern formation of wave bands.

  13. The temporal and spatial dynamics of income and population growth in Ohio, 1950-1990.

    Science.gov (United States)

    Fan, C C

    1994-01-01

    "This paper focuses on spatial variation of growth within a state. Using Ohio as a case study, two hypotheses are extracted from the literature. First, the theories of polarization and polarization reversal suggest that in the old industrial core the leading sector role of manufacturing has diminished in old manufacturing poles, and that income growth trends differ substantially between these old poles and new centres of development. Second, the theories of suburbanization and migration reversals suggest that population growth is contingent upon level of urbanization, and that the relationship has changed drastically between the pre-1970s, 1970s, and post-1970s periods." (SUMMARY IN FRE AND GER) excerpt

  14. Modeling the pre-industrial roots of modern super-exponential population growth.

    Science.gov (United States)

    Stutz, Aaron Jonas

    2014-01-01

    To Malthus, rapid human population growth-so evident in 18th Century Europe-was obviously unsustainable. In his Essay on the Principle of Population, Malthus cogently argued that environmental and socioeconomic constraints on population rise were inevitable. Yet, he penned his essay on the eve of the global census size reaching one billion, as nearly two centuries of super-exponential increase were taking off. Introducing a novel extension of J. E. Cohen's hallmark coupled difference equation model of human population dynamics and carrying capacity, this article examines just how elastic population growth limits may be in response to demographic change. The revised model involves a simple formalization of how consumption costs influence carrying capacity elasticity over time. Recognizing that complex social resource-extraction networks support ongoing consumption-based investment in family formation and intergenerational resource transfers, it is important to consider how consumption has impacted the human environment and demography--especially as global population has become very large. Sensitivity analysis of the consumption-cost model's fit to historical population estimates, modern census data, and 21st Century demographic projections supports a critical conclusion. The recent population explosion was systemically determined by long-term, distinctly pre-industrial cultural evolution. It is suggested that modern globalizing transitions in technology, susceptibility to infectious disease, information flows and accumulation, and economic complexity were endogenous products of much earlier biocultural evolution of family formation's embeddedness in larger, hierarchically self-organizing cultural systems, which could potentially support high population elasticity of carrying capacity. Modern super-exponential population growth cannot be considered separately from long-term change in the multi-scalar political economy that connects family formation and

  15. Nonylphenol stimulates fecundity but not population growth rate (λ) of Folsomia candida

    DEFF Research Database (Denmark)

    Widarto, T. H.; Krogh, P. H.; Forbes, V. E.

    2007-01-01

    of NP on these traits did not result in a statistically significant increase in population growth rate (λ). Decomposition analysis indicated that fecundity was the main contributor to the (non-significant) changes observed in λ However, since the elasticity of fecundity was very low, large changes...... at the population level and that λ is an appropriate endpoint for ecotoxicological studies. © 2007 Elsevier B.V. All rights reserved...

  16. Effects of Climate Change on Plant Population Growth Rate and Community Composition Change

    OpenAIRE

    Chang, Xiao-Yu; Chen, Bao-Ming; Liu, Gang; Zhou, Ting; Jia, Xiao-Rong; Peng, Shao-Lin

    2015-01-01

    The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of ...

  17. An application of Pontrjagin's principle to the study of the optimal growth of population

    International Nuclear Information System (INIS)

    Spinadel, V. de

    1976-01-01

    This paper examines the consequences of an optimal control of population growth and allows to derive criteria referring to the economic basis of expenditure on population control and to obtain optimal paths for a model in which such a control is possible. By means of very simple assumptions one can reduce the problem to a two-state variable control problem and, in consequence, apply Pontrjagin's maximum principle to solve it. (author)

  18. India in the Twenty-first Century: The Challenge of Population Growth. Fulbright-Hays Summer Seminars Abroad, 1997 (India).

    Science.gov (United States)

    La Fleur, Mary Ann

    This paper contains a course outline for a five-hour graduate class focusing on the issue of population in India. Students examine contributing factors to population growth, along with studying characteristics of, and efforts to, control population growth. The significance of ethnic diversity in India also is addressed. Group discussion and group…

  19. Height-growth response to climatic changes differs among populations of Douglas-fir: a novel analysis of historic data.

    Science.gov (United States)

    Leites, Laura P; Robinson, Andrew P; Rehfeldt, Gerald E; Marshall, John D; Crookston, Nicholas L

    2012-01-01

    Projected climate change will affect existing forests, as substantial changes are predicted to occur during their life spans. Species that have ample intraspecific genetic differentiation, such as Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), are expected to display population-specific growth responses to climate change. Using a mixed-effects modeling approach, we describe three-year height (HT) growth response to changes in climate of interior Douglas-fir populations. We incorporate climate information at the population level, yielding a model that is specific to both species and population. We use data from provenance tests from previous studies that comprised 236 populations from Idaho, Montana, and eastern Washington, USA. The most sensitive indicator of climate was the mean temperature of the coldest month. Population maximum HT and HT growth response to changes in climate were dependent on seed source climate. All populations had optimum HT growth when transferred to climates with warmer winters; those originating in sites with the warmest winters were taller across sites and had highest HT growth at transfer distances closest to zero; those from colder climates were shortest and had optimum HT growth when transferred the farthest. Although this differential response damped the height growth differences among populations, cold-climate populations still achieved their maximum growth at lower temperatures than warm-climate populations. The results highlight the relevance of understanding climate change impacts at the population level, particularly in a species with ample genetic variation among populations.

  20. Analysis of single hyphal growth and fragmentation in submerged cultures using a population model

    DEFF Research Database (Denmark)

    Krabben, Preben; Nielsen, Søren; Michelsen, Michael Locht

    1997-01-01

    Descriptions of population dynamics in submerged cultures are important when studying the mechanisms of growth and fragmentation of filamentous microorganisms. Population models are traditionally formulated as population balance equations. Population models of filamentous morphology are difficult...... to solve because of random fragmentation, which introduces an integral term into the population balance equations. Balances for the systemic properties, e.g. concentration of hyphal elements, substrate concentration, average total hyphal length, and average number of growing tips, are set up. Based...... on these balances one can solve the inverse problem, i.e. determination of kinetic parameters directly from measurements of the hyphal morphology. Both a Monte Carlo method and a discretization method have been used to calculate the steady-state population distribution. The two methods are compared and the Monte...

  1. Analysis of Urban Growth in Edwardsville Illinois Using Remote Sensing and Population Change

    Science.gov (United States)

    Onuoha, Hilda U.

    Rapid urbanization is one of the many critical, global issues. This very significant social and economic phenomenon has brought about much debate in the past twenty years and has become a very important policy issue. Understanding its dynamics and patterns is important to develop appropriate policies and make more informed planning decisions. Many dimensions to the urban land growth have been identified in related literature including drivers, relationship with other factors like population, impacts, and methods of measurement. In this study, urban growth in the Edwardsville area (composed of Edwardsville and Glen Carbon, Illinois) is analyzed spatio-temporally using remote sensing and population change from 1990 to 2015. The objectives of this study are (a) identifying the major land use changes in the Edwardsville area from 1990 to 2015, (b) analyzing the rate of urban growth and its relationship to population change in the area from 1990 to 2015, (c) identifying the general pattern and direction of urban growth in the study area. Using multi-temporal satellite images to classify and derive changes in land cover classes during the study period, results showed that the land cover classes with major changes are the urban/built-up land and agricultural/grassland, with a steady increase in the former and steady decrease in the later. Results also show the highest rate of increase in urban land was between 2000 and 2010. In comparison to population, the both show increase over the study years but urban land shows a higher rate of increase indicating dispersion. To analyze urban growth pattern in the area, the study area was divided into three zones: NE, SE, and W. The SE zone showed the highest amount of the growth and from the results, the infill type of growth was inferred.

  2. An exponential growth model with decreasing r captures bottom-up effects on the population growth of Aphis glycines Matsumura (Hemiptera: Aphididae)

    NARCIS (Netherlands)

    Costamagna, A.C.; Werf, van der W.; Bianchi, F.J.J.A.; Landis, D.A.

    2007-01-01

    1 There is ample evidence that the life history and population dynamics of aphids are closely linked to plant phenology. Based on life table studies, it has been proposed that the growth of aphid populations could be modeled with an exponential growth model, with r decreasing linearly with time.

  3. Near infra-red spectroscopy quantitative modelling of bivalve protein, lipid and glycogen composition using single-species versus multi-species calibration and validation sets

    Science.gov (United States)

    Bartlett, Jill K.; Maher, William A.; Purss, Matthew B. J.

    2018-03-01

    Near infrared spectroscopy (NIRS) quantitative modelling was used to measure the protein, lipid and glycogen composition of five marine bivalve species (Saccostrea glomerata, Ostrea angasi, Crassostrea gigas, Mytilus galloprovincialis and Anadara trapezia) from multiple locations and seasons. Predictive models were produced for each component using individual species and aggregated sample populations for the three oyster species (S. glomerata, O. angasi and C. gigas) and for all five bivalve species. Whole animal tissues were freeze dried, ground to > 20 μm and scanned by NIRS. Protein, lipid and glycogen composition were determined by traditional chemical analyses and calibration models developed to allow rapid NIRS-measurement of these components in the five bivalve species. Calibration modelling was performed using wavelet selection, genetic algorithms and partial least squares analysis. Model quality was assessed using RPIQ and RMESP. For protein composition, single species model results had RPIQ values between 2.4 and 3.5 and RMSEP between 8.6 and 18%, the three oyster model had an RPIQ of 2.6 and an RMSEP of 10.8% and the five bivalve species had an RPIQ of 3.6 and RMSEP of 8.7% respectively. For lipid composition, single species models achieved RPIQ values between 2.9 and 5.3 with RMSEP between 9.1 and 11.2%, the oyster model had an RPIQ of 3.6 and RMSEP of 6.8 and the five bivalve model had an RPIQ of 5.2 and RMSEP of 6.8% respectively. For glycogen composition, the single species models had RPIQs between 3.8 and 18.9 with RMSEP between 3.5 and 9.2%, the oyster model had an RPIQ of 5.5 and RMSEP of 7.1% and the five bivalve model had an RPIQ of 4 and RMSEP of 7.6% respectively. Comparison between individual species models and aggregated models for three oyster species and five bivalve species for each component indicate that aggregating data from like species produces high quality models with robust and reliable quantitative application. The benefit of

  4. Rapid Population Growth and Human Carrying Capacity: Two Perspectives. World Bank Staff Working Papers No. 690 and Population and Development Series No. 15.

    Science.gov (United States)

    Mahar, Dennis J., Ed.; And Others

    Two perspectives on carrying capacity and population growth are examined. The first perspective, "Carrying Capacity and Rapid Population Growth: Definition, Cases, and Consequences" (Robert Muscat), explores the possible meanings of the idea of carrying capacity under developing country conditions, looks at historical and present-day cases of…

  5. Impacts of breeder loss on social structure, reproduction and population growth in a social canid.

    Science.gov (United States)

    Borg, Bridget L; Brainerd, Scott M; Meier, Thomas J; Prugh, Laura R

    2015-01-01

    The importance of individuals to the dynamics of populations may depend on reproductive status, especially for species with complex social structure. Loss of reproductive individuals in socially complex species could disproportionately affect population dynamics by destabilizing social structure and reducing population growth. Alternatively, compensatory mechanisms such as rapid replacement of breeders may result in little disruption. The impact of breeder loss on the population dynamics of social species remains poorly understood. We evaluated the effect of breeder loss on social stability, recruitment and population growth of grey wolves (Canis lupus) in Denali National Park and Preserve, Alaska using a 26-year dataset of 387 radiocollared wolves. Harvest of breeding wolves is a highly contentious conservation and management issue worldwide, with unknown population-level consequences. Breeder loss preceded 77% of cases (n = 53) of pack dissolution from 1986 to 2012. Packs were more likely to dissolve if a female or both breeders were lost and pack size was small. Harvest of breeders increased the probability of pack dissolution, likely because the timing of harvest coincided with the breeding season of wolves. Rates of denning and successful recruitment were uniformly high for packs that did not experience breeder loss; however, packs that lost breeders exhibited lower denning and recruitment rates. Breeder mortality and pack dissolution had no significant effects on immediate or longer term population dynamics. Our results indicate the importance of breeding individuals is context dependent. The impact of breeder loss on social group persistence, reproduction and population growth may be greatest when average group sizes are small and mortality occurs during the breeding season. This study highlights the importance of reproductive individuals in maintaining group cohesion in social species, but at the population level socially complex species may be resilient

  6. Brief communication: Is variation in the cranial capacity of the Dmanisi sample too high to be from a single species?

    Science.gov (United States)

    Lee, Sang-Hee

    2005-07-01

    This study uses data resampling to test the null hypothesis that the degree of variation in the cranial capacity of the Dmanisi hominid sample is within the range variation of a single species. The statistical significance of the variation in the Dmanisi sample is examined using simulated distributions based on comparative samples of modern humans, chimpanzees, and gorillas. Results show that it is unlikely to find the maximum difference observed in the Dmanisi sample in distributions of female-female pairs from comparative single-species samples. Given that two sexes are represented, the difference in the Dmanisi sample is not enough to reject the null hypothesis of a single species. Results of this study suggest no compelling reason to invoke multiple taxa to explain variation in the cranial capacity of the Dmanisi hominids. (c) 2004 Wiley-Liss, Inc

  7. Nutritional status and growth of children on macrobiotic diets : a population-based study

    NARCIS (Netherlands)

    Dagnelie, P.C.

    1988-01-01

    This thesis reports on the relationship between diet, growth, blood chemistry, psychomotor development, and clinical findings in the Dutch population of children on macrobiotic diets.- The macrobiotic diet mainly consisted of cereals, pulses and vegetables with small additions of seaweeds,

  8. Population Growth Rates: Connecting Mathematics to Studies of Society and the Environment

    Science.gov (United States)

    Ninbet, Steven; Hurley, Gabrielle; Weldon, Elizabeth

    2006-01-01

    This article reports on the teaching of a unit of lessons which integrates mathematics with studies of society and the environment. The unit entitled "Population Growth Rates" was taught to a double class of Year 6 students by a team of three teachers. The objectives of the unit were: (1) to provide students with a real-world context in…

  9. Population growth and the decline of natural Southern yellow pine forests

    Science.gov (United States)

    David B. South; Edward R. Buckner

    2004-01-01

    Population growth has created social and economic pressures that affect the sustainability of naturally regenerated southern yellow pine forests. Major causes of this decline include (1) a shift in public attitudes regarding woods burning (from one favoring it to one that favors fire suppression) and (2) an increase in land values (especially near urban centers). The...

  10. Calculating second derivatives of population growth rates for ecology and evolution

    NARCIS (Netherlands)

    Shyu, E.; Caswell, H.

    2014-01-01

    Second derivatives of the population growth rate measure the curvature of its response to demographic, physiological or environmental parameters. The second derivatives quantify the response of sensitivity results to perturbations, provide a classification of types of selection and provide one way

  11. Effects of population density on the growth and egg-laying capacity ...

    African Journals Online (AJOL)

    The effects of the population density of adult African giant land snail, Archachatina marginata on the egg-laying capacity and the growth of the brooders and hatchlings were investigated for 9 months. Ten culture pens were stocked with snails at 20%, 40%, 60%, 80% and 100% capacity with each group in 2 replicates.

  12. The growth of population and employment in the Dar es Salaam city region, Tanzania.

    Science.gov (United States)

    Hayuma, A M

    1983-01-01

    The problems of rapid population growth and unemployment in the Dar es Salaam urban region, Tanzania, are discussed. Efforts to deal with these problems through the 1968 Dar es Salaam master plan are reviewed, and the ineffectiveness of the plan to date is noted.

  13. Does pollen limitation affect population growth of the endangered Dracocephalum austriacum L.?

    Czech Academy of Sciences Publication Activity Database

    Castro, Sílvia; Dostálek, Tomáš; van der Meer, S.; Oostermeijer, G.; Münzbergová, Zuzana

    2015-01-01

    Roč. 57, č. 1 (2015), s. 105-116 ISSN 1438-3896 R&D Projects: GA ČR GP13-10850P; GA ČR GAP505/10/0593 Institutional support: RVO:67985939 Keywords : Dracocephalum austriacum * pollination ecology * population growth rate Subject RIV: EF - Botanics Impact factor: 1.698, year: 2015

  14. Growth of the human lens in the Indian adult population: Preliminary observations

    Directory of Open Access Journals (Sweden)

    Ashik Mohamed

    2012-01-01

    Full Text Available Context: The eye lens grows throughout life by the addition of new cells inside the surrounding capsule. How this growth affects the properties of the lens is essential for understanding disorders such as cataract and presbyopia. Aims: To examine growth of the human lens in the Indian population and compare this with the growth in Western populations by measuring in vitro dimensions together with wet and dry weights. Settings and Design: The study was conducted at the research wing of a tertiary eye care center in South India and the study design was prospective. Materials and Methods: Lenses were removed from eye bank eyes and their dimensions measured with a digital caliper. They were then carefully blotted dry and weighed before being placed in 5% buffered formalin. After 1 week fixation, the lenses were dried at 80 °C until constant weight was achieved. The constant weight was noted as the dry weight of the lens. Statistical Analysis Used: Lens parameters were analyzed as a function of age using linear and logarithmic regression methods. Results: Data were obtained for 251 lenses, aged 16-93 years, within a median postmortem time of 22 h. Both wet and dry weights increased linearly at 1.24 and 0.44 mg/year, respectively, throughout adult life. The dimensions also increased continuously throughout this time. Conclusions: Over the age range examined, lens growth in the Indian population is very similar to that in Western populations.

  15. Population growth in a wild bird is buffered against phenological mismatch

    NARCIS (Netherlands)

    Reed, T.; Grotan, V.; Jenouvrier, S.; Saether, B.E.; Visser, M.E.

    2013-01-01

    road-scale environmental changes are altering patterns of natural selection in the wild, but few empirical studies have quantified the demographic cost of sustained directional selection in response to these changes. We tested whether population growth in a wild bird is negatively affected by

  16. Growth of the human lens in the Indian adult population: preliminary observations.

    Science.gov (United States)

    Mohamed, Ashik; Sangwan, Virender S; Augusteyn, Robert C

    2012-01-01

    The eye lens grows throughout life by the addition of new cells inside the surrounding capsule. How this growth affects the properties of the lens is essential for understanding disorders such as cataract and presbyopia. To examine growth of the human lens in the Indian population and compare this with the growth in Western populations by measuring in vitro dimensions together with wet and dry weights. The study was conducted at the research wing of a tertiary eye care center in South India and the study design was prospective. Lenses were removed from eye bank eyes and their dimensions measured with a digital caliper. They were then carefully blotted dry and weighed before being placed in 5% buffered formalin. After 1 week fixation, the lenses were dried at 80 °C until constant weight was achieved. The constant weight was noted as the dry weight of the lens. Lens parameters were analyzed as a function of age using linear and logarithmic regression methods. Data were obtained for 251 lenses, aged 16-93 years, within a median postmortem time of 22 h. Both wet and dry weights increased linearly at 1.24 and 0.44 mg/year, respectively, throughout adult life. The dimensions also increased continuously throughout this time. Over the age range examined, lens growth in the Indian population is very similar to that in Western populations.

  17. Connecting phenological predictions with population growth rates for mountain pine beetle, an outbreak insect

    Science.gov (United States)

    James A. Powell; Barbara J. Bentz

    2009-01-01

    It is expected that a significant impact of global warming will be disruption of phenology as environmental cues become disassociated from their selective impacts. However there are few, if any, models directly connecting phenology with population growth rates. In this paper we discuss connecting a distributional model describing mountain pine beetle phenology with a...

  18. An accessibility approach to railways and municipal population growth, 1840-1930

    NARCIS (Netherlands)

    Huijg, A.; Koopmans, C.; Rietveld, P.

    2010-01-01

    In the nineteenth century, railway networks strongly improved accessibility. In this paper we examine the impact of accessibility improvements on municipal population growth in the Netherlands between 1840 and 1930, using census data. By mapping a multimodal transport network and calculating the

  19. An accessibility approach to railways and municipal population growth, 1840-1930

    NARCIS (Netherlands)

    Koopmans, C.; Rietveld, P.; Huijg, A.

    2012-01-01

    In the 19th century, railway networks strongly improved accessibility. In this paper we examine the impact of accessibility improvements on municipal population growth in the Netherlands between 1840 and 1930, using census data. By mapping a multimodal transport network and calculating the shortest

  20. Growth rates and variances of unexploited wolf populations in dynamic equilibria

    Science.gov (United States)

    Mech, L. David; Fieberg, John

    2015-01-01

    Several states have begun harvesting gray wolves (Canis lupus), and these states and various European countries are closely monitoring their wolf populations. To provide appropriate perspective for determining unusual or extreme fluctuations in their managed wolf populations, we analyzed natural, long-term, wolf-population-density trajectories totaling 130 years of data from 3 areas: Isle Royale National Park in Lake Superior, Michigan, USA; the east-central Superior National Forest in northeastern Minnesota, USA; and Denali National Park, Alaska, USA. Ratios between minimum and maximum annual sizes for 2 mainland populations (n = 28 and 46 yr) varied from 2.5–2.8, whereas for Isle Royale (n = 56 yr), the ratio was 6.3. The interquartile range (25th percentile, 75th percentile) for annual growth rates, Nt+1/Nt, was (0.88, 1.14), (0.92, 1.11), and (0.86, 1.12) for Denali, Superior National Forest, and Isle Royale respectively. We fit a density-independent model and a Ricker model to each time series, and in both cases we considered the potential for observation error. Mean growth rates from the density-independent model were close to 0 for all 3 populations, with 95% credible intervals including 0. We view the estimated model parameters, including those describing annual variability or process variance, as providing useful summaries of the trajectories of these populations. The estimates of these natural wolf population parameters can serve as benchmarks for comparison with those of recovering wolf populations. Because our study populations were all from circumscribed areas, fluctuations in them represent fluctuations in densities (i.e., changes in numbers are not confounded by changes in occupied area as would be the case with populations expanding their range, as are wolf populations in many states).

  1. Growth Indicators of a 48-Clone Sugar Cane Population (Saccharum spp. with Forage Potential

    Directory of Open Access Journals (Sweden)

    Yoslen Fernández Gálvez

    2016-09-01

    Full Text Available The aim of this paper was to determine growth indicators in a 48-clone sugar cane population, with promising phenotypical features for forage production. The following indicators were assessed: leaf area (A, leaf area index (LA1; leaf area ratio (LAR; specific leaf area (SLA; leaf weight ratio (LWR; crop growth rate (CGR; net assimilation rate (NAR; relative growth rate in weight (RGR; biomass production speed (G; leaf area duration (LAD; and biomass duration (Z, monthly (187 - 370 days. The minimum, the mean, the maximum values, and the population variance were determined for all cutting ages and the variables assessed. The results achieved have provided quantitative values that can be used as reference for selection and assessment of forage genotypes for ruminant nutrition.

  2. Individualism in plant populations: using stochastic differential equations to model individual neighbourhood-dependent plant growth.

    Science.gov (United States)

    Lv, Qiming; Schneider, Manuel K; Pitchford, Jonathan W

    2008-08-01

    We study individual plant growth and size hierarchy formation in an experimental population of Arabidopsis thaliana, within an integrated analysis that explicitly accounts for size-dependent growth, size- and space-dependent competition, and environmental stochasticity. It is shown that a Gompertz-type stochastic differential equation (SDE) model, involving asymmetric competition kernels and a stochastic term which decreases with the logarithm of plant weight, efficiently describes individual plant growth, competition, and variability in the studied population. The model is evaluated within a Bayesian framework and compared to its deterministic counterpart, and to several simplified stochastic models, using distributional validation. We show that stochasticity is an important determinant of size hierarchy and that SDE models outperform the deterministic model if and only if structural components of competition (asymmetry; size- and space-dependence) are accounted for. Implications of these results are discussed in the context of plant ecology and in more general modelling situations.

  3. Meeting the Sustainable Development Goals leads to lower world population growth.

    Science.gov (United States)

    Abel, Guy J; Barakat, Bilal; Kc, Samir; Lutz, Wolfgang

    2016-12-13

    Here we show the extent to which the expected world population growth could be lowered by successfully implementing the recently agreed-upon Sustainable Development Goals (SDGs). The SDGs include specific quantitative targets on mortality, reproductive health, and education for all girls by 2030, measures that will directly and indirectly affect future demographic trends. Based on a multidimensional model of population dynamics that stratifies national populations by age, sex, and level of education with educational fertility and mortality differentials, we translate these goals into SDG population scenarios, resulting in population sizes between 8.2 and 8.7 billion in 2100. Because these results lie outside the 95% prediction range given by the 2015 United Nations probabilistic population projections, we complement the study with sensitivity analyses of these projections that suggest that those prediction intervals are too narrow because of uncertainty in baseline data, conservative assumptions on correlations, and the possibility of new policies influencing these trends. Although the analysis presented here rests on several assumptions about the implementation of the SDGs and the persistence of educational, fertility, and mortality differentials, it quantitatively illustrates the view that demography is not destiny and that policies can make a decisive difference. In particular, advances in female education and reproductive health can contribute greatly to reducing world population growth.

  4. Induction of prophage lambda by chlorinated organics: Detection of some single-species/single-site carcinogens

    Energy Technology Data Exchange (ETDEWEB)

    DeMarini, D.M.; Brooks, H.G. (Environmental Protection Agency, Research Triangle Park, NC (United States))

    1992-01-01

    Twenty-eight chlorinated organic compounds were evaluated for their ability to induce DNA damage using the Microscreen prophage-induction assay in Escherichia coli. Comparison of the performance characteristics of the prophage-induction and Salmonella assays to rodent carcinogenicity assays showed that the prophage-induction assay had a somewhat higher specificity than did the Salmonella assay (70% vs. 50%); sensitivity, concordance, and positive and negative predictivity were similar for the two microbial assays. The Microscreen prophage-induction assay failed to detect eight carcinogens, perhaps due to toxicity or other unknown factors; five of these eight carcinogens were detected by the Salmonella assay. However, the prophage-induction assay did detect six carcinogens that were not detected by the Salmonella assay, and five of these were single-species, single-site carcinogens, mostly mouse liver carcinogens. Some of these carcinogens, such as the chloroethanes, produce free radicals, which may be the basis for their carcinogenicity and ability to induce prophage. The prophage-induction (or other SOS) assay may be useful in identifying some genotoxic chlorinated carcinogens that induce DNA damage that do not revert the standard Salmonella tester strains.

  5. A deep-sea agglutinated foraminifer tube constructed with planktonic foraminifer shells of a single species

    Science.gov (United States)

    Pearson, Paul N.; Expedition 363 Shipboard Scientific Party, IODP

    2018-01-01

    Agglutinated foraminifera are marine protists that show apparently complex behaviour in constructing their shells, involving selecting suitable sedimentary grains from their environment, manipulating them in three dimensions, and cementing them precisely into position. Here we illustrate a striking and previously undescribed example of complex organisation in fragments of a tube-like foraminifer (questionably assigned to Rhabdammina) from 1466 m water depth on the northwest Australian margin. The tube is constructed from well-cemented siliciclastic grains which form a matrix into which hundreds of planktonic foraminifer shells are regularly spaced in apparently helical bands. These shells are of a single species, Turborotalita clarkei, which has been selected to the exclusion of all other bioclasts. The majority of shells are set horizontally in the matrix with the umbilical side upward. This mode of construction, as is the case with other agglutinated tests, seems to require either an extraordinarily selective trial-and-error process at the site of cementation or an active sensory and decision-making system within the cell.

  6. JOB DISCRIMINATION AGAINST WOMEN AND ENDOGENOUS POPULATION CHANGE IN A GENERALIZED SOLOW GROWTH MODEL

    Directory of Open Access Journals (Sweden)

    Wei-Bin ZHANG

    2017-06-01

    Full Text Available This study examines economic growth and population change with discrimination against women in the labor market within the analytical framework of Solow’s neoclassical growth model. The study models dynamic interactions between wealth accumulation, time distribution between work, children caring, and leisure, population change with endogenous birth and mortality rates with gender discrimination. The production technology and markets are built on Solow’s neoclassical growth model. The basic mechanisms for population changes in the Barro-Becker fertility choice model and the Haavelmo population model are integrated to model the population change. This study also takes account of discrimination against woman in the labor market. We synthesize these dynamic forces in a compact framework by applying Zhang’s utility function. The model properties are studied by simulation. We find equilibrium points and illustrate motion of the dynamic system. We also examine the effects of changes in the discrimination against woman, the propensity to save, woman’s propensity to pursue leisure activities, the propensity to have children, woman’s human capital and man’s emotional involvement in children caring.

  7. Uncertainty in population growth rates: determining confidence intervals from point estimates of parameters.

    Directory of Open Access Journals (Sweden)

    Eleanor S Devenish Nelson

    Full Text Available BACKGROUND: Demographic models are widely used in conservation and management, and their parameterisation often relies on data collected for other purposes. When underlying data lack clear indications of associated uncertainty, modellers often fail to account for that uncertainty in model outputs, such as estimates of population growth. METHODOLOGY/PRINCIPAL FINDINGS: We applied a likelihood approach to infer uncertainty retrospectively from point estimates of vital rates. Combining this with resampling techniques and projection modelling, we show that confidence intervals for population growth estimates are easy to derive. We used similar techniques to examine the effects of sample size on uncertainty. Our approach is illustrated using data on the red fox, Vulpes vulpes, a predator of ecological and cultural importance, and the most widespread extant terrestrial mammal. We show that uncertainty surrounding estimated population growth rates can be high, even for relatively well-studied populations. Halving that uncertainty typically requires a quadrupling of sampling effort. CONCLUSIONS/SIGNIFICANCE: Our results compel caution when comparing demographic trends between populations without accounting for uncertainty. Our methods will be widely applicable to demographic studies of many species.

  8. Why sustainable population growth is a key to climate change and public health equity.

    Science.gov (United States)

    Howat, Peter; Stoneham, Melissa

    2011-12-01

    Australia's population could reach 42 million by 2050. This rapid population growth, if unabated, will have significant social, public health and environmental implications. On the one hand, it is a major driver of climate change and environmental degradation; on the other it is likely to be a major contributor to growing social and health issues including a decline in quality of life for many residents. Disadvantaged and vulnerable groups will be most affected. The environmental, social and health-related issues include: pressure on the limited arable land in Australia; increased volumes of industrial and domestic waste; inadequate essential services; traffic congestion; lack of affordable housing; declining mental health; increased obesity problems; and inadequate aged care services. Many of these factors are related to the aggravation of climate change and health inequities. It is critical that the Australian Government develops a sustainable population plan with stabilisation of population growth as an option. The plan needs to ensure adequate hospitals and healthcare services, education facilities, road infrastructure, sustainable transport options, water quality and quantity, utilities and other amenities that are already severely overburdened in Australian cities. There is a need for a guarantee that affordable housing will be available and priority be given to training young people and Indigenous people for employment. This paper presents evidence to support the need for the stabilisation of population growth as one of the most significant measures to control climate change as well as to improve public health equity.

  9. Effect of Cadmium on the population growth of the marine diatom Chaetoceros gracilis Schutt

    Directory of Open Access Journals (Sweden)

    Giovana Vera

    2014-06-01

    Full Text Available Phytoplankton constitutes the base of the trophic webs in the marine environment, so it is important to know the possible effects of pollutants on the algal populations. In the present paper the effect of cadmium on the population growth of the diatom Chaetoceros gracilis was assessed. The microalgae were cultured in the a modified “f/2” Guillard medium, and were exposed to different concentrations of cadmium between 50 and 100000 µg.–1, which produced an inhibitory effect from 20% to 99% on the population growth of Chaetoceros gracilis. Based on the dose (cadmium-response (inhibition relationship, a mean effective concentration (EC50% equal to 591 µg.L–1 of cadmium was obtained.

  10. Effects of growth curve plasticity on size-structured population dynamics

    DEFF Research Database (Denmark)

    Zhang, Lai; Lin, Zhigui; Pedersen, Michael

    2011-01-01

    . The dilemma results from the possibility that adults have to breed even if metabolic costs fail to be covered.We consider a size-structured population model, where standard metabolism is given top priority for utilizing energy intake and the surplus energy, if there is any, is distributed to individual growth...... and reproduction. Moreover, the portion of surplus energy for reproduction is size-dependent and increases monotonically with size. Using the newly developed parameter continuation, we demonstrate their disparate effects on population dynamics. Results show that the size-dependent mechanism of energy allocation......The physiological-structured population models assume that a fixed fraction of energy intake is utilized for individual growth and maintenance while the remaining for adult fertility. The assumption results in two concerns: energy loss for juveniles and a reproduction dilemma for adults...

  11. Effects of climate change on long-term population growth of pronghorn in an arid environment

    Science.gov (United States)

    Gedir, Jay V.; Cain, James W.; Harris, Grant; Turnbull, Trey T.

    2015-01-01

    Climate often drives ungulate population dynamics, and as climates change, some areas may become unsuitable for species persistence. Unraveling the relationships between climate and population dynamics, and projecting them across time, advances ecological understanding that informs and steers sustainable conservation for species. Using pronghorn (Antilocapra americana) as an ecological model, we used a Bayesian approach to analyze long-term population, precipitation, and temperature data from 18 populations in the southwestern United States. We determined which long-term (12 and 24 months) or short-term (gestation trimester and lactation period) climatic conditions best predicted annual rate of population growth (λ). We used these predictions to project population trends through 2090. Projections incorporated downscaled climatic data matched to pronghorn range for each population, given a high and a lower atmospheric CO2 concentration scenario. Since the 1990s, 15 of the pronghorn populations declined in abundance. Sixteen populations demonstrated a significant relationship between precipitation and λ, and in 13 of these, temperature was also significant. Precipitation predictors of λ were highly seasonal, with lactation being the most important period, followed by early and late gestation. The influence of temperature on λ was less seasonal than precipitation, and lacked a clear temporal pattern. The climatic projections indicated that all of these pronghorn populations would experience increased temperatures, while the direction and magnitude of precipitation had high population-specific variation. Models predicted that nine populations would be extirpated or approaching extirpation by 2090. Results were consistent across both atmospheric CO2 concentration scenarios, indicating robustness of trends irrespective of climatic severity. In the southwestern United States, the climate underpinning pronghorn populations is shifting, making conditions increasingly

  12. The Effects of Population Density on Juvenile Growth Rate in White-Tailed Deer

    Science.gov (United States)

    Barr, Brannon; Wolverton, Steve

    2014-10-01

    Animal body size is driven by habitat quality, food availability, and nutrition. Adult size can relate to birth weight, to length of the ontogenetic growth period, and/or to the rate of growth. Data requirements are high for studying these growth mechanisms, but large datasets exist for some game species. In North America, large harvest datasets exist for white-tailed deer ( Odocoileus virginianus), but such data are collected under a variety of conditions and are generally dismissed for ecological research beyond local population and habitat management. We contend that such data are useful for studying the ecology of white-tailed deer growth and body size when analyzed at ordinal scale. In this paper, we test the response of growth rate to food availability by fitting a logarithmic equation that estimates growth rate only to harvest data from Fort Hood, Texas, and track changes in growth rate over time. Results of this ordinal scale model are compared to previously published models that include additional parameters, such as birth weight and adult weight. It is shown that body size responds to food availability by variation in growth rate. Models that estimate multiple parameters may not work with harvest data because they are prone to error, which renders estimates from complex models too variable to detect interannual changes in growth rate that this ordinal scale model captures. This model can be applied to harvest data, from which inferences about factors that influence animal growth and body size (e.g., habitat quality and nutritional availability) can be drawn.

  13. Impact of population and economic growth on carbon emissions in Taiwan using an analytic tool STIRPAT

    Directory of Open Access Journals (Sweden)

    Jong-Chao Yeh

    2017-01-01

    Full Text Available Carbon emission has increasingly become an issue of global concern because of climate change. Unfortunately, Taiwan was listed as top 20 countries of carbon emission in 2014. In order to provide appropriate measures to control carbon emission, it appears that there is an urgent need to address how such factors as population and economic growth impact the emission of carbon dioxide in any developing countries. In addition to total population, both the percentages of population living in urban area (i.e., urbanization percentage, and non-dependent population may also serve as limiting factors. On the other hand, the total energy-driven gross domestic production (GDP and the percentage of GDP generated by the manufacturing industries are assessed to see their respective degree of impact on carbon emission. Therefore, based on the past national data in the period 1990–2014 in Taiwan, an analytic tool of Stochastic Impacts by Regression on Population, Affluence and Technology (STIRPAT was employed to see how well those aforementioned factors can describe their individual potential impact on global warming, which is measured by the total amount of carbon emission into the atmosphere. Seven scenarios of STIRPAT model were proposed and tested statistically for the significance of each proposed model. As a result, two models were suggested to predict the impact of carbon emission due to population and economic growth by the year 2025 in Taiwan.

  14. Population structure, growth and production of a recent brachiopod from the Chilean fjord region

    KAUST Repository

    Baumgarten, Sebastian

    2013-12-04

    Magellania venosa, the largest recent brachiopod, occurs in clusters and banks in population densities of up to 416 ind m-2 in Comau Fjord, Northern Chilean fjord region. Below 15 m, it co-occurs with the mytilid Aulacomya atra and it dominates the benthic community below 20 m. To determine the question of why M. venosa is a successful competitor, the in situ growth rate of the brachiopod was studied and its overall growth performance compared with that of other brachiopods and mussels. The growth in length was measured between February 2011 and March 2012 after mechanical tagging and calcein staining. Settlement and juvenile growth were determined from recruitment tiles installed in 2009 and from subsequent photocensus. Growth of M. venosa is best described by the general von Bertalanffy growth function, with a maximum shell length (L∞) of 71.53 mm and a Brody growth constant (K) of 0.336 year-1. The overall growth performance (OGP index = 5.1) is the highest recorded for a rynchonelliform brachiopod and in the range of that for Mytilus chilensis (4.8-5.27), but lower than that of A. atra (5.74). The maximal individual production (PInd) is 0.29 g AFDM ind-1 year-1 at 42 mm shell length and annual production ranges from 1.28 to 89.25 g AFDM year-1 m-2 (1-57% of that of A. atra in the respective fjords). The high shell growth rate of M. venosa, together with its high overall growth performance may explain the locally high population density of this brachiopod in Comau Fjord. However, the production per biomass of the population (P/B--ratio) is low (0.535) and M. venosa may play only a minor role in the food chain. Settling dynamics indicates that M. venosa is a pioneer species with low juvenile mortality. The coexistence of the brachiopod and bivalve suggests that brachiopod survival is affected by neither the presence of potential brachiopod predators nor that of space competitors (i.e. mytilids).

  15. Are whooping cranes destined for extinction? Climate change imperils recruitment and population growth.

    Science.gov (United States)

    Butler, Matthew J; Metzger, Kristine L; Harris, Grant M

    2017-04-01

    Identifying climatic drivers of an animal population's vital rates and locating where they operate steers conservation efforts to optimize species recovery. The population growth of endangered whooping cranes ( Grus americana ) hinges on juvenile recruitment. Therefore, we identify climatic drivers (solar activity [sunspots] and weather) of whooping crane recruitment throughout the species' life cycle (breeding, migration, wintering). Our method uses a repeated cross-validated absolute shrinkage and selection operator approach to identify drivers of recruitment. We model effects of climate change on those drivers to predict whooping crane population growth given alternative scenarios of climate change and solar activity. Years with fewer sunspots indicated greater recruitment. Increased precipitation during autumn migration signified less recruitment. On the breeding grounds, fewer days below freezing during winter and more precipitation during breeding suggested less recruitment. We predicted whooping crane recruitment and population growth may fall below long-term averages during all solar cycles when atmospheric CO 2 concentration increases, as expected, to 500 ppm by 2050. Species recovery during a typical solar cycle with 500 ppm may require eight times longer than conditions without climate change and the chance of population decline increases to 31%. Although this whooping crane population is growing and may appear secure, long-term threats imposed by climate change and increased solar activity may jeopardize its persistence. Weather on the breeding grounds likely affects recruitment through hydrological processes and predation risk, whereas precipitation during autumn migration may influence juvenile mortality. Mitigating threats or abating climate change should occur within ≈30 years or this wild population of whooping cranes may begin declining.

  16. Impact of Population Growth and Climate Change on the Freshwater Resources of Lamu Island, Kenya

    Directory of Open Access Journals (Sweden)

    Cornelius Okello

    2015-03-01

    Full Text Available Demand for freshwater is rising with factors, such as population growth, land use change and climate variations, rendering water availability in the future uncertain. Groundwater resources are being increasingly exploited to meet this growing demand. The aim of this study is to identify the influence of population growth induced by land use change and climate change on the future state of freshwater resources of Lamu Island in Kenya where a major port facility is under construction. The results of this study show that the “no industrial development” population scenario (assuming the port was not constructed would be expected to reach ~50,000 people by 2050, while the projected population upon completion is expected to reach 1.25 million in the same year when the Lamu Port-South Sudan-Ethiopia Transport Corridor Program (LAPSSET port reaches its full cargo-handling capacity. The groundwater abstraction in 2009 was 0.06 m3 daily per capita, while the demand is expected to raise to 0.1 m3 by 2050 according to the “LAPSSET development” projection. The modelling results show that the Shela aquifer in Lamu, which is the main source of water on the island, will not experience stress by 2065 for the “no industrial development” population scenario, whereas for the “LAPSSET development projection” population scenario, it will occur sooner (between 2020 and 2028. The modelling results show that the Representative Concentration Pathways (RCP climate change scenarios will have a smaller impact on the effective water volume reserves than Special Report on Emissions Scenarios (SRES for the “no industrial development”, while the impact is expected to be similar for the “LAPSSET development”, suggesting that population growth exacerbated by land use change will be a more significant driving force than climate change in affecting freshwater availability.

  17. Endogenous growth of population and income depending on resource and knowledge.

    Science.gov (United States)

    Prskawetz, A; Feichtinger, G; Luptacik, M; Milik, A; Wirl, F; Hof, F; Lutz, W

    1999-01-01

    This study focuses on the dynamic, endogenous, nonlinear interactions between the economy, population growth and the environment. Literature on endogenous growth theory was reviewed and the 3-sector demoeconomic model was provided as the analytical framework for the study of sustainable development through the integration of population growth, resource use and economic growth. The model is described in such a way that the labor force is considered as a free migrating variable among three different kinds of employment: the primary sector, which harvests a renewable resource, the secondary or industrial sector, and the tertiary sector, which is responsible for the accumulation of the stock that represents a public good for all three sectors. Presented in this paper is a nontechnical outline of the model that describes the economic, demographic, and environmental interactions considered. Also given are dynamics, market equilibrium and dynamic feedback rules. Furthermore, numerical analysis of the model quantifying the resulting time paths of the variables involved is included. The dynamics are simply the outcome of the nonlinear interactions of the demographic, economic and environmental modules. Numerical studies have also shown that the system variables move with different velocity. Technology and population can generally be regarded as slow moving variables by comparison with resources.

  18. POPULATION AND REPRODUCTIVE GROWTH OF ROE DEER, Capreolus capreolus Linnaeus, 1758. IN THE HUNTING GROUND "CREPOLJSKO"

    Directory of Open Access Journals (Sweden)

    Enad Korjenić

    2013-03-01

    Full Text Available Field research of population and reproductive growth of roe deer, Capreolus capreolus Linnaeus, 1758. in the hunting ground "Crepoljsko" lasted from January to December 2009. In the studied hunting ground two habitats (sites of roe deer Nahorevo and Bukovik have been registered with the estimated area of 1900 ha. Nahorevo covers, approximately 800 ha, and Bukovik 1100 ha. The total number of roe deer individuals in the "Crepoljsko" estimated to 103 individuals. In hunting ground Nahorevo 42 individual of roe deer of various age structure have been documented. Absolute reproductive growth of deer in this study area was six individuals or 45% of the expected (theoretical reproductive growth (60%. In hunting ground Bukovik 61 individuals have been found. Absolute reproductive growth was 9 individuals which makes 49% of theoretical reproductive growth. On the basis these results it could be concluded that the investigated habitats (sites have suitable conditions for this attractive hunting deer, as wall as for the development of hunting tourism and education. Key words: deer, population, reproduction, habitat

  19. Living bacteria rheology: Population growth, aggregation patterns, and collective behavior under different shear flows

    Science.gov (United States)

    Patrício, P.; Almeida, P. L.; Portela, R.; Sobral, R. G.; Grilo, I. R.; Cidade, T.; Leal, C. R.

    2014-08-01

    The activity of growing living bacteria was investigated using real-time and in situ rheology—in stationary and oscillatory shear. Two different strains of the human pathogen Staphylococcus aureus—strain COL and its isogenic cell wall autolysis mutant, RUSAL9—were considered in this work. For low bacteria density, strain COL forms small clusters, while the mutant, presenting deficient cell separation, forms irregular larger aggregates. In the early stages of growth, when subjected to a stationary shear, the viscosity of the cultures of both strains increases with the population of cells. As the bacteria reach the exponential phase of growth, the viscosity of the cultures of the two strains follows different and rich behaviors, with no counterpart in the optical density or in the population's colony-forming units measurements. While the viscosity of strain COL culture keeps increasing during the exponential phase and returns close to its initial value for the late phase of growth, where the population stabilizes, the viscosity of the mutant strain culture decreases steeply, still in the exponential phase, remains constant for some time, and increases again, reaching a constant plateau at a maximum value for the late phase of growth. These complex viscoelastic behaviors, which were observed to be shear-stress-dependent, are a consequence of two coupled effects: the cell density continuous increase and its changing interacting properties. The viscous and elastic moduli of strain COL culture, obtained with oscillatory shear, exhibit power-law behaviors whose exponents are dependent on the bacteria growth stage. The viscous and elastic moduli of the mutant culture have complex behaviors, emerging from the different relaxation times that are associated with the large molecules of the medium and the self-organized structures of bacteria. Nevertheless, these behaviors reflect the bacteria growth stage.

  20. [The population growth in the city of Beijing and our present tasks (author's transl)].

    Science.gov (United States)

    Qian, L J; Xu, B; Huang, S Y

    1980-04-01

    Concern for the rapid population growth since 1949 of China's second largest city, Beijing, is discussed in terms of population control, migration, and rises in the productive development of the city. From 1949 to 1963 the natural rate of population increased from 7.5 to 35.3%; however, after the introduction of a birth control program in 1971, the natural increase of population declined to 4.02% in 1977. From 1949-1978, the average birth rate was 145,000/year while the average death rate was 46,500/year, leaving the annual average increase in population at 98,000. The natural population increased by 2,340,000 from 1949-1978. The massive population growth since 1949 affected the economic development of the city as well as the country. Cultivated land near Beijing increased from 1949-1952, but because of urban development the land for cultivation decreased by 1,527,000 market acres from that available in 1949 (7,965,000 market acres). Population density increased from 430 persons/ square kilometer in 1962 to 506 persons/ square kilometer in 1978. From 1953 to 1978, production and consumption rates fluctuated with a net balance of only 2020 million catties in the 26 years, causing the need for products to be imported from other areas of the country. Unemployment is exacerbated by the lack of jobs and increasing numbers of people. Transportation problems also have developed. New efforts are being made to inform people of population control by the Beijing Population Association begun in 1979, because Beijing's population will continue to increase until 1989 due to the baby boom years during the fifties which created a 2nd boom in the late 1970s as well as the lack of education on population control. Other programs are being developed to, 1) educate people on economical measures of reducing the population, 2) promote governmental departments to improve birth control programs by means of social security services, child health agencies, and nursing schools, 3

  1. Development and population growth of Hydra viridissima Pallas, 1766 (Cnidaria, Hydrozoa in the laboratory

    Directory of Open Access Journals (Sweden)

    FC. Massaro

    Full Text Available Hydras, the most representative freshwater Cnidaria, are of common occurrence in bodies of water in every continent except Antarctica. This study was planned with the aim of maintaining a population of Hydra viridissima in laboratory culture to enable the determination of the individual and population growth-rates of this species, as well as its population doubling time and generation time, with a view to employing these common animals as test-organisms in ecotoxicological assays. The organisms were maintained in reconstituted water at 20 ± 2 °C, illuminated at 800 lux with a photoperiod of 12 hours light: 12 hours dark, and were fed on neonates of the cladoceran Ceriodaphnia silvestrii (3 or 4 neonates per hydra, 3 times a week. The individual growth-rate (k of the species was 0.43, the maximum length of the column 2.53 mm and the generation time 6.6 ± 1.5 days on average. The hydra population showed an intrinsic growth-rate (r of 0.0468, according to the fitted curve, and a doubling time of 14.8 ± 2.63 days. Hydra viridissima is easy to grow in the laboratory and performs well in the conditions used in this study. It is thus a promising candidate test-organism for ecotoxicological studies.

  2. Conservation of avian diversity in the Sierra Nevada: moving beyond a single-species management focus.

    Directory of Open Access Journals (Sweden)

    Angela M White

    greater benefit to ecosystem functioning then a single-species management focus.

  3. Conservation of avian diversity in the Sierra Nevada: moving beyond a single-species management focus.

    Science.gov (United States)

    White, Angela M; Zipkin, Elise F; Manley, Patricia N; Schlesinger, Matthew D

    2013-01-01

    ecosystem functioning then a single-species management focus.

  4. Single-species versus dual-species probiotic supplementation as an emerging therapeutic strategy for obesity.

    Science.gov (United States)

    Karimi, G; Jamaluddin, R; Mohtarrudin, N; Ahmad, Z; Khazaai, H; Parvaneh, M

    2017-10-01

    Recent studies have reported beneficial effects of specific probiotics on obesity. However, the difference in the anti-obesity effects of probiotics as single species and dual species is still uncertain. Therefore, we aimed to compare the efficacy of single and dual species of bacteria on markers of obesity in high-fat diet-induced obese rats. A total of 40 male Sprague-Dawley rats were assigned to one of five groups of varying diets as follows: standard diet, high fat diet (HFD), HFD supplemented with Lactobacillus casei strain Shirota, HFD supplemented with Bifidobacterium longum and HFD supplemented with a mixture of these two bacterial species. After 15 weeks of supplementation, the animals were examined for changes in body weight, body fat, total count of bacteria in fecal, blood serum lipid profile, leptin, adiponectin and inflammatory biomarkers. Histological analysis of the liver and adipose tissue was performed and the hepatic mRNA expression levels of genes related to lipid metabolism were measured. It was found that probiotic supplementation of either B. longum or a mixture of B. longum and LcS bacteria significantly reduced weight and triglycerides in the HFD groups. Supplementation of B. longum bacteria showed better results in terms of modulating leptin level, fat mass, adipocyte size and lipoprotein lipase expression, as well as increasing adiponectin and peroxisome proliferator-activated receptors-γ expression compared to dual species of bacteria. No significant differences were observed in the total count of fecal bacteria, glucose and inflammatory biomarker levels between supplemented groups. B. longum supplementation in obesity was more beneficial in metabolic profile changes than the mixture species. Copyright © 2017 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B

  5. The growth hormone system and cardiac function in patients with growth hormone disturbances and in the normal population.

    Science.gov (United States)

    Andreassen, Mikkel

    2010-10-01

    Pathological high and low levels of Insulin-like Growth factor I (IGF-I) might exert harmful influences on cardiovascular structures. In the normal population low IGF-I levels might be harmful. In a retrospective investigation in patients with growth hormone deficiency (GHD), normal levels of NT-proBNP at baseline and no changes during two years of GH treatment could be detected. A subsequent prospective study confirmed normal levels of NT-proBNP and also of BNP. Furthermore cardiac systolic function and left ventricle (LV) mass assessed by cardiac magnetic resonance imaging (CMRI) were unchanged compared to control subjects. One year of GH replacement therapy did not change levels of NT-proBNP, BNP or any of the variables obtained by CMRI. In a retrospective study of acromegalic patients we found reduced serum NT-proBNP in the untreated stage and a 4-fold increase after 3 months of treatment. A subsequent prospective CMRI investigation confirmed an initial increase in natriuretic peptides after 3 months treatment, and showed that the increase in natriuretic peptides was accompanied by an increase in end diastolic volume. In a normal population followed prospectively for 5 years, high plasma IGF-I was accompanied by increased incidence of chronic heart failure, whereas IGF-I levels did not seem to influence the overall development of cardiovascular diseases. assessed by sensitive methods patients with GHD had normal systolic function, and one year of GH replacement therapy did not change LV function or size. In acromegalic patients short-term treatment was associated with a minor decrease in cardiac function. In the normal population high levels of IGF-I was a risk factor for development of heart failure. The results illustrates that the interaction between the GH/IGF-I system and cardiovascular disease is very complex.

  6. Increasing Dengue Incidence in Singapore over the Past 40 Years: Population Growth, Climate and Mobility.

    Directory of Open Access Journals (Sweden)

    Claudio Jose Struchiner

    Full Text Available In Singapore, the frequency and magnitude of dengue epidemics have increased significantly over the past 40 years. It is important to understand the main drivers for the rapid increase in dengue incidence. We studied the relative contributions of putative drivers for the rise of dengue in Singapore: population growth, climate parameters and international air passenger arrivals from dengue endemic countries, for the time period of 1974 until 2011. We used multivariable Poisson regression models with the following predictors: Annual Population Size; Aedes Premises Index; Mean Annual Temperature; Minimum and Maximum Temperature Recorded in each year; Annual Precipitation and Annual Number of Air Passengers arriving from dengue-endemic South-East Asia to Singapore. The relative risk (RR of the increase in dengue incidence due to population growth over the study period was 42.7, while the climate variables (mean and minimum temperature together explained an RR of 7.1 (RR defined as risk at the end of the time period relative to the beginning and goodness of fit associated with the model leading to these estimates assessed by pseudo-R2 equal to 0.83. Estimating the extent of the contribution of these individual factors on the increasing dengue incidence, we found that population growth contributed to 86% while the residual 14% was explained by increase in temperature. We found no correlation with incoming air passenger arrivals into Singapore from dengue endemic countries. Our findings have significant implications for predicting future trends of the dengue epidemics given the rapid urbanization with population growth in many dengue endemic countries. It is time for policy-makers and the scientific community alike to pay more attention to the negative impact of urbanization and urban climate on diseases such as dengue.

  7. Beaver-mediated methane emission: The effects of population growth in Eurasia and the Americas.

    Science.gov (United States)

    Whitfield, Colin J; Baulch, Helen M; Chun, Kwok P; Westbrook, Cherie J

    2015-02-01

    Globally, greenhouse gas budgets are dominated by natural sources, and aquatic ecosystems are a prominent source of methane (CH(4)) to the atmosphere. Beaver (Castor canadensis and Castor fiber) populations have experienced human-driven change, and CH(4) emissions associated with their habitat remain uncertain. This study reports the effect of near extinction and recovery of beavers globally on aquatic CH4 emissions and habitat. Resurgence of native beaver populations and their introduction in other regions accounts for emission of 0.18-0.80 Tg CH(4) year(-1) (year 2000). This flux is approximately 200 times larger than emissions from the same systems (ponds and flowing waters that became ponds) circa 1900. Beaver population recovery was estimated to have led to the creation of 9500-42 000 km(2) of ponded water, and increased riparian interface length of >200 000 km. Continued range expansion and population growth in South America and Europe could further increase CH(4) emissions.

  8. Stochastic population growth in spatially heterogeneous environments: the density-dependent case.

    Science.gov (United States)

    Hening, Alexandru; Nguyen, Dang H; Yin, George

    2018-02-01

    This work is devoted to studying the dynamics of a structured population that is subject to the combined effects of environmental stochasticity, competition for resources, spatio-temporal heterogeneity and dispersal. The population is spread throughout n patches whose population abundances are modeled as the solutions of a system of nonlinear stochastic differential equations living on [Formula: see text]. We prove that r, the stochastic growth rate of the total population in the absence of competition, determines the long-term behaviour of the population. The parameter r can be expressed as the Lyapunov exponent of an associated linearized system of stochastic differential equations. Detailed analysis shows that if [Formula: see text], the population abundances converge polynomially fast to a unique invariant probability measure on [Formula: see text], while when [Formula: see text], the population abundances of the patches converge almost surely to 0 exponentially fast. This generalizes and extends the results of Evans et al. (J Math Biol 66(3):423-476, 2013) and proves one of their conjectures. Compared to recent developments, our model incorporates very general density-dependent growth rates and competition terms. Furthermore, we prove that persistence is robust to small, possibly density dependent, perturbations of the growth rates, dispersal matrix and covariance matrix of the environmental noise. We also show that the stochastic growth rate depends continuously on the coefficients. Our work allows the environmental noise driving our system to be degenerate. This is relevant from a biological point of view since, for example, the environments of the different patches can be perfectly correlated. We show how one can adapt the nondegenerate results to the degenerate setting. As an example we fully analyze the two-patch case, [Formula: see text], and show that the stochastic growth rate is a decreasing function of the dispersion rate. In particular, coupling two

  9. Mutually catalyzed birth of population and assets in exchange-driven growth

    Science.gov (United States)

    Lin, Zhenquan; Ke, Jianhong; Ye, Gaoxiang

    2006-10-01

    We propose an exchange-driven aggregation growth model of population and assets with mutually catalyzed birth to study the interaction between the population and assets in their exchange-driven processes. In this model, monomer (or equivalently, individual) exchange occurs between any pair of aggregates of the same species (population or assets). The rate kernels of the exchanges of population and assets are K(k,l)=Kkl and L(k,l)=Lkl , respectively, at which one monomer migrates from an aggregate of size k to another of size l . Meanwhile, an aggregate of one species can yield a new monomer by the catalysis of an arbitrary aggregate of the other species. The rate kernel of asset-catalyzed population birth is I(k,l)=Iklμ [and that of population-catalyzed asset birth is J(k,l)=Jklν ], at which an aggregate of size k gains a monomer birth when it meets a catalyst aggregate of size l . The kinetic behaviors of the population and asset aggregates are solved based on the rate equations. The evolution of the aggregate size distributions of population and assets is found to fall into one of three categories for different parameters μ and ν : (i) population (asset) aggregates evolve according to the conventional scaling form in the case of μ⩽0 (ν⩽0) , (ii) population (asset) aggregates evolve according to a modified scaling form in the case of ν=0 and μ>0 ( μ=0 and ν>0 ), and (iii) both population and asset aggregates undergo gelation transitions at a finite time in the case of μ=ν>0 .

  10. Morphological variation in Plantago lanceolata L.: effects of light quality and growth regulators on sun and shade populations

    NARCIS (Netherlands)

    Van Hinsberg, A.

    1997-01-01

    The effects of different ratios of red io far-red light (R/FR- ratio) and of exogenously applied growth regulators on the morphology of plants from sun and shade populations were studied. Large differences in growth form were found between populations adapted to either sun or shaded habitats. Low

  11. Impacts of population growth, urbanisation and sanitation changes on global human Cryptosporidium emissions to surface water.

    Science.gov (United States)

    Hofstra, Nynke; Vermeulen, Lucie C

    2016-10-01

    Cryptosporidium is a pathogenic protozoan parasite and is a leading cause of diarrhoea worldwide. The concentration of Cryptosporidium in the surface water is a determinant for probability of exposure and the risk of disease. Surface water concentrations are expected to change with population growth, urbanisation and changes in sanitation. The objective of this paper is to assess the importance of future changes in population, urbanisation and sanitation on global human emissions of Cryptosporidium to surface water. The GloWPa-Crypto H1 (the Global Waterborne Pathogen model for Human Cryptosporidium emissions version 1) model is presented and run for 2010 and with scenarios for 2050. The new scenarios are based on the Shared Socio-economic Pathways (SSPs) developed for the climate community. The scenarios comprise assumptions on sanitation changes in line with the storylines and population and urbanisation changes from the SSPs. In SSP1 population growth is limited, urbanisation large and sanitation and waste water treatment strongly improve. SSP1* is the same as SSP1, but waste water treatment does not improve. SSP3 sees large population growth, moderate urbanisation and sanitation and waste water treatment fractions that are the same as in 2010. Total global Cryptosporidium emissions to surface water for 2010 are estimated to be 1.6×10 17 oocysts per year, with hotspots in the most urbanised parts of the world. In 2050 emissions are expected to decrease by 24% or increase by 52% and 70% for SSP1, SSP3 and SSP1* respectively. The emissions increase in all scenarios for countries in the Middle East and Africa (MAF) region, while emissions in large parts in Europe decrease in scenarios SSP1 and SSP3. Improving sanitation by connecting the population to sewers, should be combined with waste water treatment, otherwise (SSP1*) emissions in 2050 are expected to be much larger than in a situation with strong population growth and slow development of safe water and

  12. Human population growth offsets climate-driven increase in woody vegetation in sub-Saharan Africa

    DEFF Research Database (Denmark)

    Brandt, Martin Stefan; Rasmussen, Kjeld; Peñuelas, Josep

    2017-01-01

    The rapidly growing human population in sub-Saharan Africa generates increasing demand for agricultural land and forest products, which presumably leads to deforestation. Conversely, a greening of African drylands has been reported, but this has been difficult to associate with changes in woody...... cover were associated with high population growth. The spatially distinct pattern of these opposing trends reflects, first, the natural response of vegetation to precipitation and atmospheric CO2, and second, deforestation in humid areas, minor in size but important for ecosystem services...

  13. The Impact of Population Ageing on Technological Progress and TFP Growth, with Application to United States: 1950-2050

    OpenAIRE

    Izmirlioglu, Yusuf

    2008-01-01

    I examine the effect of age-distribution of the society on economic growth through technological progress. I build a multisector economy model that involves population pyramid. I characterize the steady-state of the model for low and high population growth rate. Higher population growth rate yields faster TFP and output growth in the long-run. I analyze dynamic behavior of the economy. I calibrate the model for United States, 1950-2000 and using the estimated parameters I make predictions abo...

  14. Effects of Population Growth and Climate Variability on Sustainable Groundwater in Mali, West Africa

    Directory of Open Access Journals (Sweden)

    Alexandra Lutz

    2010-12-01

    Full Text Available Groundwater is increasingly relied on as a source of potable water in developing countries, but factors such as population growth, development, and climate variability, pose potential challenges for ongoing sustainable supply. The effect of these factors on the groundwater system was considered in four scenarios using a numerical model to represent the Bani area of Mali, West Africa. By 2040, population growth, climate variability, and development as urbanization, agriculture, and industry creates scenarios in which groundwater extraction is an increasingly larger percentage of the groundwater system. Consumption from agriculture and industry increases extraction rates from less than 1 to 3.8% of mean annual precipitation, which will likely affect the groundwater system. For instance, concentrated pumping in local areas may result in water level declines. The results of this study contribute to an ongoing evaluation of sustainable groundwater resources in West Africa.

  15. Fetal growth and risk of stillbirth: a population-based case-control study.

    Science.gov (United States)

    Bukowski, Radek; Hansen, Nellie I; Willinger, Marian; Reddy, Uma M; Parker, Corette B; Pinar, Halit; Silver, Robert M; Dudley, Donald J; Stoll, Barbara J; Saade, George R; Koch, Matthew A; Rowland Hogue, Carol J; Varner, Michael W; Conway, Deborah L; Coustan, Donald; Goldenberg, Robert L

    2014-04-01

    Stillbirth is strongly related to impaired fetal growth. However, the relationship between fetal growth and stillbirth is difficult to determine because of uncertainty in the timing of death and confounding characteristics affecting normal fetal growth. We conducted a population-based case-control study of all stillbirths and a representative sample of live births in 59 hospitals in five geographic areas in the US. Fetal growth abnormalities were categorized as small for gestational age (SGA) (90th percentile) at death (stillbirth) or delivery (live birth) using population, ultrasound, and individualized norms. Gestational age at death was determined using an algorithm that considered the time-of-death interval, postmortem examination, and reliability of the gestational age estimate. Data were weighted to account for the sampling design and differential participation rates in various subgroups. Among 527 singleton stillbirths and 1,821 singleton live births studied, stillbirth was associated with SGA based on population, ultrasound, and individualized norms (odds ratio [OR] [95% CI]: 3.0 [2.2 to 4.0]; 4.7 [3.7 to 5.9]; 4.6 [3.6 to 5.9], respectively). LGA was also associated with increased risk of stillbirth using ultrasound and individualized norms (OR [95% CI]: 3.5 [2.4 to 5.0]; 2.3 [1.7 to 3.1], respectively), but not population norms (OR [95% CI]: 0.6 [0.4 to 1.0]). The associations were stronger with more severe SGA and LGA (95th percentile). Analyses adjusted for stillbirth risk factors, subset analyses excluding potential confounders, and analyses in preterm and term pregnancies showed similar patterns of association. In this study 70% of cases and 63% of controls agreed to participate. Analysis weights accounted for differences between consenting and non-consenting women. Some of the characteristics used for individualized fetal growth estimates were missing and were replaced with reference values. However, a sensitivity analysis using individualized norms

  16. Effect of microstructure on population growth parameters of Escherichia coli in gelatin-dextran systems.

    Science.gov (United States)

    Boons, Kathleen; Noriega, Estefanía; Van den Broeck, Rob; David, Charlotte C; Hofkens, Johan; Van Impe, Jan F

    2014-09-01

    Current literature acknowledges the effect of food structure on bacterial dynamics. Most studies introduce this "structure" factor using a single gelling agent, resulting in a homogeneous environment, whereas in practice most food products are heterogeneous. Therefore, this study focuses on heterogeneous protein-polysaccharide mixtures, based on gelatin and dextran. These mixtures show phase separation, leading to a range of heterogeneous microstructures by adjusting relative concentrations of both gelling agents. Based on confocal microscope observations, the growth of Escherichia coli in gelatin-dextran systems was observed to occur in the dextran phase. To find a relation between microscopic and population behavior, growth experiments were performed in binary and singular gelatin-dextran systems and culture broth at 23.5°C, with or without adding 2.9% (wt/vol) NaCl. The Baranyi and Roberts growth model was fitted to the experimental data and parameter estimates were statistically compared. For salted binary mixtures, a decrease in the population maximum cell density was observed with increasing gelatin concentration. In this series, for one type of microstructure, i.e., a gelatin matrix phase with a disperse dextran phase, the maximum cell density decreased with decreasing percentage of dextran phase. However, this relation no longer held when other types of microstructure were observed. Compared to singular systems, adding a second gelling agent in the presence of NaCl had an effect on population lag phases and maximum cell densities. For unsalted media, the growth parameters of singular and binary mixtures were comparable. Introducing this information into mathematical models leads to more reliable growth predictions and enhanced food safety. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  17. Growth Performance Of Mono-Sex And Mixed Sex Population Of ...

    African Journals Online (AJOL)

    The growth performance of all-male, all-female and mixed sex population of Oreochromis niloticus fed similar diet was carried out. The fingerlings used in the study were of relatively similar weight ranges (24.8 g – 26.6 g) with initial mean weight of 25.7±1.3 g and initial mean total length of 3.8 ± 1.5 cm. The mean increase ...

  18. Stationary solutions to a system of size-structured populations with nonlinear growth rate.

    Science.gov (United States)

    Kato, Nobuyuki

    2012-01-01

    We study stationary solutions to a system of size-structured population models with nonlinear growth rate. Several characterizations of stationary solutions are provided. It is shown that the steady-state problem can be converted into different problems such as two types of eigenvalue problems and a fixed-point problem. In the two-species case, we give an existence result of nonzero stationary solutions by using the fixed-point problem.

  19. Rate and Time Trend of Perinatal, Infant, Maternal Mortality, Natality and Natural Population Growth in Kosovo

    OpenAIRE

    Azemi, Mehmedali; Gashi, Sanije; Berisha, Majlinda; Kolgeci, Selim; Ismaili-Jaha, Vlora

    2012-01-01

    Aim: The aim of work has been the presentation of the rate and time trends of some indicators of the heath condition of mothers and children in Kosovo: fetal mortality, early neonatal mortality, perinatal mortality, infant mortality, natality, natural growth of population etc. The treated patients were the newborn and infants in the post neonatal period, women during their pregnancy and those 42 days before and after the delivery. Methods: The data were taken from: register of the patients tr...

  20. Population Growth Rate, Life Expectancy and Pension Program Improvement in China

    OpenAIRE

    Yang, Zaigui

    2008-01-01

    Applying an overlapping-generations model with lifetime uncertainty, we examine in this paper China’s partially funded public pension system. The findings show that the individual contribution rate does not affect the capital-labor ratio but the firm contribution rate does. The optimal firm contribution rate depends on the capital share of income, social discount factor, survival probability, and population growth rate. The simulation results indicate that the optimal firm contribution rate r...

  1. Verification of SNPs Associated with Growth Traits in Two Populations of Farmed Atlantic Salmon

    Directory of Open Access Journals (Sweden)

    Hsin Y. Tsai

    2015-12-01

    Full Text Available Understanding the relationship between genetic variants and traits of economic importance in aquaculture species is pertinent to selective breeding programmes. High-throughput sequencing technologies have enabled the discovery of large numbers of SNPs in Atlantic salmon, and high density SNP arrays now exist. A previous genome-wide association study (GWAS using a high density SNP array (132K SNPs has revealed the polygenic nature of early growth traits in salmon, but has also identified candidate SNPs showing suggestive associations with these traits. The aim of this study was to test the association of the candidate growth-associated SNPs in a separate population of farmed Atlantic salmon to verify their effects. Identifying SNP-trait associations in two populations provides evidence that the associations are true and robust. Using a large cohort (N = 1152, we successfully genotyped eight candidate SNPs from the previous GWAS, two of which were significantly associated with several growth and fillet traits measured at harvest. The genes proximal to these SNPs were identified by alignment to the salmon reference genome and are discussed in the context of their potential role in underpinning genetic variation in salmon growth.

  2. The relationship between population ageing and the economic growth in Asia

    Science.gov (United States)

    Brendan, Lo Rick; Sek, Siok Kun

    2017-08-01

    Asia has witnessed robust economic growth since the 1960s. Today, emerging markets in Asia have managed to maintain rapid growth even when the world's main economies suffer from debt and banking crises. However, declining total fertility rate, increasing life expectancy, continuous change of birth and death patterns, and increasing share of old age population in the age distribution in Asia exert significant pressure on its economies. This paper analyses the relationship between population ageing and economic growth using 2 different panels of countries; one Asian and another the from the oldest countries worldwide between 1970 and 2014. The analysis is based on the Auto Regression Distributed Lag models. The MG (Mean Group) and PMG (Pooled Mean Group) estimations are applied in this analysis. The Hausman Test is conducted to decide between the MG and PMG estimators. We find that ageing will negatively affect the economy in the long run. The growing number of youths will initially have a negative effect on the economy but would eventually lead to a positive growth in the future. The old age dependency ratio has yet to have affect the Asian economy but is expected eventually to impose a negative effect as seen in the oldest nations of the world.

  3. Using a laboratory-based growth model to estimate mass- and temperature-dependent growth parameters across populations of juvenile Chinook Salmon

    Science.gov (United States)

    Perry, Russell W.; Plumb, John M.; Huntington, Charles

    2015-01-01

    To estimate the parameters that govern mass- and temperature-dependent growth, we conducted a meta-analysis of existing growth data from juvenile Chinook Salmon Oncorhynchus tshawytscha that were fed an ad libitum ration of a pelleted diet. Although the growth of juvenile Chinook Salmon has been well studied, research has focused on a single population, a narrow range of fish sizes, or a narrow range of temperatures. Therefore, we incorporated the Ratkowsky model for temperature-dependent growth into an allometric growth model; this model was then fitted to growth data from 11 data sources representing nine populations of juvenile Chinook Salmon. The model fit the growth data well, explaining 98% of the variation in final mass. The estimated allometric mass exponent (b) was 0.338 (SE = 0.025), similar to estimates reported for other salmonids. This estimate of b will be particularly useful for estimating mass-standardized growth rates of juvenile Chinook Salmon. In addition, the lower thermal limit, optimal temperature, and upper thermal limit for growth were estimated to be 1.8°C (SE = 0.63°C), 19.0°C (SE = 0.27°C), and 24.9°C (SE = 0.02°C), respectively. By taking a meta-analytical approach, we were able to provide a growth model that is applicable across populations of juvenile Chinook Salmon receiving an ad libitum ration of a pelleted diet.

  4. Uropathogenic Escherichia coli Express Type 1 Fimbriae Only in Surface Adherent Populations Under Physiological Growth Conditions.

    Science.gov (United States)

    Stærk, Kristian; Khandige, Surabhi; Kolmos, Hans Jørn; Møller-Jensen, Jakob; Andersen, Thomas Emil

    2016-02-01

    Most uropathogenic Escherichia coli (UPEC) strains harbor genes encoding adhesive type 1 fimbria (T1F). T1F is a key factor for successful establishment of urinary tract infection. However, UPEC strains typically do not express T1F in the bladder urine, and little is understood about its induction in vivo. A flow chamber infection model was used to grow UPEC under conditions simulating distinct infection niches in the bladder. Type 1 fimbriation on isolated UPEC was subsequently determined by yeast cell agglutination and immunofluorescence microscopy, and the results were correlated with the ability to adhere to and invade cultured human bladder cells. Although inactive during planktonic growth in urine, T1F expression occurs when UPEC settles on and infects bladder epithelial cells or colonizes catheters. As a result, UPEC in these sessile populations enhances bladder cell adhesion and invasion potential. Only T1F-negative UPEC are subsequently released to the urine, thus limiting T1F expression to surface-associated UPEC alone. Our results demonstrate that T1F expression is strictly regulated under physiological growth conditions with increased expression during surface growth adaptation and infection of uroepithelial cells. This leads to separation of UPEC into low-expression planktonic populations and high-expression sessile populations. © The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  5. A demographic projection of the contribution of assisted reproductive technologies to world population growth.

    Science.gov (United States)

    Faddy, Malcolm J; Gosden, Matthew D; Gosden, Roger G

    2018-04-01

    Enormous unmet needs for infertility treatment exist because access to assisted reproductive technologies is demographically skewed. Since the first IVF baby in 1978, the number of people conceived by reproductive technology has grown much faster than expected, reaching several million today and rapidly approaching 0.1% of the total world population. As more patients build families, and their children in turn become parents, the number owing their existence to assisted reproductive technologies, either directly or indirectly, will expand tremendously in future decades, but no attempts have been made hitherto to project the magnitude. We have projected growth to the year 2100, along with the fractional contribution to world population. The chief variable driving growth is access to fertility services. If it stagnates at current levels of about 400,000 babies per year, an estimated 157 million people alive at the end of the century will owe their lives to assisted reproductive technologies (1.4% of global population), but at an arbitrary upper limit of 30,000 extra births annually there will be 394 million additional people alive (3.5%). As the conquest of infertility continues, individuals who owe their lives to assisted reproductive technologies will quietly make a significant contribution to demographic growth as well as social progress. Copyright © 2018. Published by Elsevier Ltd.

  6. Population growth, interest rate, and housing tax in the transitional China

    Science.gov (United States)

    He, Ling-Yun; Wen, Xing-Chun

    2017-03-01

    This paper combines and develops the models in Lastrapes (2002) and Mankiw and Weil (1989), which enables us to analyze the effects of interest rate and population growth shocks on housing price in one integrated framework. Based on this model, we carry out policy simulations to examine whether the housing (stock or flow) tax reduces the housing price fluctuations caused by interest rate or population growth shocks. Simulation results imply that the choice of housing tax tools depends on the kind of shock that housing market faces. In the situation where the housing price volatility is caused by the population growth shock, the flow tax can reduce the volatility of housing price while the stock tax makes no difference to it. If the shock is resulting from the interest rate, the policy maker should not impose any kind of the housing taxes. Furthermore, the effect of one kind of the housing tax can be strengthened by that of the other type of housing tax.

  7. Large nonlethal effects of an invasive invertebrate predator on zooplankton population growth rate.

    Science.gov (United States)

    Pangle, Kevin L; Peacor, Scott D; Johannsson, Ora E

    2007-02-01

    We conducted a study to determine the contribution of lethal and nonlethal effects to a predator's net effect on a prey's population growth rate in a natural setting. We focused on the effects of an invasive invertebrate predator, Bythotrephes longimanus, on zooplankton prey populations in Lakes Michigan and Erie. Field data taken at multiple dates and locations in both systems indicated that the prey species Daphnia mendotae, Daphnia retrocurva, and Bosmina longirostris inhabited deeper portions of the water column as Bythotrephes biomass increased, possibly as an avoidance response to predation. This induced migration reduces predation risk but also can reduce birth rate due to exposure to cooler temperatures. We estimated the nonlethal (i.e., resulting from reduced birth rate) and lethal (i.e., consumptive) effects of Bythotrephes on D. mendotae and Bosmina longirostris. These estimates used diel field survey data of the vertical gradient of zooplankton prey density, Bythotrephes density, light intensity, and temperature with growth and predation rate models derived from laboratory studies. Results indicate that nonlethal effects played a substantial role in the net effect of Bythotrephes on several prey population growth rates in the field, with nonlethal effects on the same order of magnitude as or greater (up to 10-fold) than lethal effects. Our results further indicate that invasive species can have strong nonlethal, behaviorally based effects, despite short evolutionary coexistence with prey species.

  8. Population Growth and Sprawl on the Pine Ridge Indian Reservation, South Dakota

    Science.gov (United States)

    Campbell, R. L.

    2006-05-01

    The most important impact on global land cover is human use and development. With the recent population growth occurring on the reservations in South Dakota, especially Pine Ridge Indian Reservation, the towns and agricultural areas of the reservation are undergoing a change. Although urban sprawl certainly is not a consideration on the reservations, the population explosion currently underway has seen a subsequent increase in rural sprawl. In this case, rural sprawl is defined as exponential population growth and geographic expansion of remote reservation communities. Using satellite imagery and software to render these images is a cost effective way to investigate this growth. Also, using remotely sensed data and a GIS (geographic information system) package can address different issues that concern people and communities in and around the Pine Ridge area. The objective of my project is to observe land use change on the Pine Ridge Indian reservation using Geographic Information Systems such as; ARCGis 9, ENVI, and Multispec, along with Landsat 4, 5, and 7 imagery over the past 20 years.

  9. Exon 3-deleted and full-length growth hormone receptor polymorphism frequencies in an Iranian population.

    Science.gov (United States)

    Palizban, A A; Radmansorry, M; Bozorgzad, M

    2014-01-01

    The functional role of the exon 3 growth hormone receptor (d3GHR) polymorphism in human and its distributions in different populations is not clearly understood. The presence of full length growth hormone (flGHR) is the most important in metabolic risk factors. The aim of this study was to define the frequency distribution of d3GHR/full-length GHR in an Iranian population. The presence of the d3GHR polymorphism in healthy volunteers blood DNA (n=80, male=30 and female=50) was assessed by PCR using specific primers. The 935-bp and 592-bp fragments indicate the presence of the flGHR and the exon3 deletion of GHR, respectively. The distribution of the GHR genotypes in this study were 31.4% (n=24) for fl/flGHR, 49.7 % (n=41) for fl/d3GHR, and 19.0 % (n=15) for d3/d3GHR. Frequencies of fl allele and d3 allele were 55.4% and 44.4% within whole population, respectively. There was no difference in allels frequencies of GHR in male (fl=0.583, d3=0.417) and female (fl=0.540, d3=0.460) when compared with whole population. The results showed that the frequency of d3/d3GHR isoform was significantly lower than that of the fl/flGHR and d3/flGHR. The frequencies of GHR polymorphisms were likely consistent with previous reports. Our finding is also consistant with Mexican population. The advantage of existence of the d3/d3 rather than fl/flGHR polymorphisms in individuals and in correlation with diseases opens new insights for GH and insilin-like-growth factor-1 (IGF-I) axis.

  10. Determining individual variation in growth and its implication for life-history and population processes using the empirical Bayes method.

    Directory of Open Access Journals (Sweden)

    Simone Vincenzi

    2014-09-01

    Full Text Available The differences in demographic and life-history processes between organisms living in the same population have important consequences for ecological and evolutionary dynamics. Modern statistical and computational methods allow the investigation of individual and shared (among homogeneous groups determinants of the observed variation in growth. We use an Empirical Bayes approach to estimate individual and shared variation in somatic growth using a von Bertalanffy growth model with random effects. To illustrate the power and generality of the method, we consider two populations of marble trout Salmo marmoratus living in Slovenian streams, where individually tagged fish have been sampled for more than 15 years. We use year-of-birth cohort, population density during the first year of life, and individual random effects as potential predictors of the von Bertalanffy growth function's parameters k (rate of growth and L∞ (asymptotic size. Our results showed that size ranks were largely maintained throughout marble trout lifetime in both populations. According to the Akaike Information Criterion (AIC, the best models showed different growth patterns for year-of-birth cohorts as well as the existence of substantial individual variation in growth trajectories after accounting for the cohort effect. For both populations, models including density during the first year of life showed that growth tended to decrease with increasing population density early in life. Model validation showed that predictions of individual growth trajectories using the random-effects model were more accurate than predictions based on mean size-at-age of fish.

  11. Individual-based modelling of population growth and diffusion in discrete time.

    Directory of Open Access Journals (Sweden)

    Natalie Tkachenko

    Full Text Available Individual-based models (IBMs of human populations capture spatio-temporal dynamics using rules that govern the birth, behavior, and death of individuals. We explore a stochastic IBM of logistic growth-diffusion with constant time steps and independent, simultaneous actions of birth, death, and movement that approaches the Fisher-Kolmogorov model in the continuum limit. This model is well-suited to parallelization on high-performance computers. We explore its emergent properties with analytical approximations and numerical simulations in parameter ranges relevant to human population dynamics and ecology, and reproduce continuous-time results in the limit of small transition probabilities. Our model prediction indicates that the population density and dispersal speed are affected by fluctuations in the number of individuals. The discrete-time model displays novel properties owing to the binomial character of the fluctuations: in certain regimes of the growth model, a decrease in time step size drives the system away from the continuum limit. These effects are especially important at local population sizes of <50 individuals, which largely correspond to group sizes of hunter-gatherers. As an application scenario, we model the late Pleistocene dispersal of Homo sapiens into the Americas, and discuss the agreement of model-based estimates of first-arrival dates with archaeological dates in dependence of IBM model parameter settings.

  12. REGIONAL COMPONENTS OF GROWTH THE QUALITY OF LIFE OF THE POPULATION (FOR EXAMPLE, VORONEZH REGION

    Directory of Open Access Journals (Sweden)

    N. A. Serebryakova

    2015-01-01

    Full Text Available At the present stage of development of economy there is a transformation of main objectives of the state from ensuring growth of welfare of citizens to ensuring continuous growth of quality of life. Ensuring growth of quality of life of the population is carried out not only on state, but also on regional levels. At the state level key tasks are formed, the state assumes a considerable share of functions on achievement of the designated purpose. In the real research the attention to consideration of the program documents directed on improvement of quality of life of the population on the example of the Voronezh region is paid. The program documents of a social orientation existing in the region are for this purpose studied. It is revealed that in the region a number of the programs and subprogrammes aimed at improvement of a demographic situation, improvement of a regional budgetary and tax policy, social support of citizens in general works. As tools which use regional authorities, are noted: social standards, address social help, social contracts. It is established that introduction of system of social contracts allows to save budget funds and, at the same time, to motivate the persons which are in a difficult life situation on change of the situation to the best, joint efforts with social security authorities. It is noted that as the leading principles of rendering the social help paramount value has detailed definition of degree of need of the help and a condition of granting. The last often generate dependant moods which are important for leveling, using levers of social interaction. The analysis of the contents of the realized programs for improvement of quality of life of the population allowed to reveal advantages and defects in these programs, and also to define reserves of growth of quality of life. So, it is specified that program documents of regional level in the prevailing majority have a narrow focus on ensuring the help and

  13. The impact of population growth on environment: the debate heats up.

    Science.gov (United States)

    Shaw, R P

    1992-02-01

    A proposed framework, which was introduced at the 1989 meetings of the American Association for the Advancement of Science, included political constraints as well as population growth as a proximate cause with potentially important impacts on the environment in Paul and Ann Ehrlich's well-known PAT equation. PAT limitations are identified as the 1.2 billion people caught in the debt-poverty trap, less developed countries' balance of payments deficits, and "distortionary factors" that undermined economic incentives and contributed to mismanagement of resources. Such factors could be keeping farm prices low and have an impact on deterring use of environmentally sound traditional agricultural practices. Mismanagement of public lands occurs when large commercial enterprises or large scale mechanization displace population onto marginal or less productive lands. Intergroup warfare is a new form impacting on the environment. In Burma loggers are authorized to clear cut large tracts of teak forests in order to ferret out Karen guerrillas. Over 15 million refugees were thus displaced and forced to live in encampments that require trees for shelter, firewood for survival, and overgrazing of livestock. Social and economic environments are also undermined by "dependency" factors such as trade protectionism, brain drain, and limited foreign aid. The Group of 77 Non-Aligned Developing Countries proposed that discussions of the links between population and the environment be omitted from the agenda of the 1994 UN Conference on Population and Development. Basic clarifications are needed to distinguish ultimate versus proximate factors and current versus future concerns. The debate ignores distribution patterns, migration, or changing age structures. The debate blames unjustifiably rapid population growth as the ultimate cause of global environmental degradation and links population growth to a host of other social problems such as famine and refugees, while ignoring civil unrest

  14. Climate threats on growth of rear-edge European beech peripheral populations in Spain

    Science.gov (United States)

    Dorado-Liñán, I.; Akhmetzyanov, L.; Menzel, A.

    2017-12-01

    European beech ( Fagus sylvatica L.) forests in the Iberian Peninsula are a clear example of a temperate forest tree species at the rear edge of its large distribution area in Europe. The expected drier and warmer climate may alter tree growth and species distribution. Consequently, the peripheral populations will most likely be the most threatened ones. Four peripheral beech forests in the Iberian Peninsula were studied in order to assess the climate factors influencing tree growth for the last six decades. The analyses included an individual tree approach in order to detect not only the changes in the sensitivity to climate but also the potential size-mediated sensitivity to climate. Our results revealed a dominant influence of previous and current year summer on tree growth during the last six decades, although the analysis in two equally long periods unveiled changes and shifts in tree sensitivity to climate. The individual tree approach showed that those changes in tree response to climate are not size dependent in most of the cases. We observed a reduced negative effect of warmer winter temperatures at some sites and a generalized increased influence of previous year climatic conditions on current year tree growth. These results highlight the crucial role played by carryover effects and stored carbohydrates for future tree growth and species persistence.

  15. Local environment and density-dependent feedbacks determine population growth in a forest herb

    DEFF Research Database (Denmark)

    Dahlgren, Johan Petter; Östergård, Hannah; Ehrlén, Johan

    2014-01-01

    Linking spatial variation in environmental factors to variation in demographic rates is essential for a mechanistic understanding of the dynamics of populations. However, we still know relatively little about such links, partly because feedbacks via intraspecific density make them difficult...... shade on survival and growth, while density was negatively correlated with these vital rates. Density was also negatively correlated with average individual size in the study plots, which is consistent with self-thinning. In addition, average plant sizes were larger than predicted by density in plots...... similar to those observed in the field. The results illustrate how the local environment can determine dynamics of populations and that intraspecific density may have to be more carefully considered in studies of plant demography and population viability analyses of threatened species. We conclude...

  16. Anatomy of a bottleneck: diagnosing factors limiting population growth in the Puerto Rican parrot

    Science.gov (United States)

    Beissenger, S.R.; Wunderle, J.M.; Meyers, J.M.; Saether, B.-E.; Engen, S.

    2008-01-01

    The relative importance of genetic, demographic, environmental, and catastrophic processes that maintain population bottlenecks has received little consideration. We evaluate the role of these factors in maintaining the Puerto Rican Parrot (Amazona vittata) in a prolonged bottleneck from 1973 through 2000 despite intensive conservation efforts. We first conduct a risk analysis, then examine evidence for the importance of specific processes maintaining the bottleneck using the multiple competing hypotheses approach, and finally integrate these results through a sensitivity analysis of a demographic model using life-stage simulation analysis (LSA) to determine the relative importance of genetic, demographic, environmental, and catastrophic processes on population growth. Annual population growth has been slow and variable (1.0 6 5.2 parrots per year, or an average k?1.05 6 0.19) from 16 parrots (1973) to a high of 40-42 birds (1997-1998). A risk analysis based on population prediction intervals (PPI) indicates great risk and large uncertainty, with a range of 22?83 birds in the 90% PPI only five years into the future. Four primary factors (reduced hatching success due to inbreeding, failure of adults to nest, nest failure due to nongenetic causes, and reduced survival of adults and juveniles) were responsible for maintaining the bottleneck. Egghatchability rates were low (70.6% per egg and 76.8% per pair), and hatchability increased after mate changes, suggesting inbreeding effects. Only an average of 34% of the population nested annually, which was well below the percentage of adults that should have reached an age of first breeding (41-56%). This chronic failure to nest appears to have been caused primarily by environmental and/or behavioral factors, and not by nest-site scarcity or a skewed sex ratio. Nest failure rates from nongenetic causes (i.e., predation, parasitism, and wet cavities) were low (29%) due to active management (protecting nests and fostering

  17. Local environment and density-dependent feedbacks determine population growth in a forest herb.

    Science.gov (United States)

    Dahlgren, Johan P; Ostergård, Hannah; Ehrlén, Johan

    2014-12-01

    Linking spatial variation in environmental factors to variation in demographic rates is essential for a mechanistic understanding of the dynamics of populations. However, we still know relatively little about such links, partly because feedbacks via intraspecific density make them difficult to observe in natural populations. We conducted a detailed field study and investigated simultaneous effects of environmental factors and the intraspecific density of individuals on the demography of the herb Lathyrus vernus. In regression models of vital rates we identified effects associated with spring shade on survival and growth, while density was negatively correlated with these vital rates. Density was also negatively correlated with average individual size in the study plots, which is consistent with self-thinning. In addition, average plant sizes were larger than predicted by density in plots that were less shaded by the tree canopy, indicating an environmentally determined carrying capacity. A size-structured integral projection model based on the vital rate regressions revealed that the identified effects of shade and density were strong enough to produce differences in stable population sizes similar to those observed in the field. The results illustrate how the local environment can determine dynamics of populations and that intraspecific density may have to be more carefully considered in studies of plant demography and population viability analyses of threatened species. We conclude that demographic approaches incorporating information about both density and key environmental factors are powerful tools for understanding the processes that interact to determine population dynamics and abundances.

  18. Spatial analysis of cattle and shoat population in Ethiopia: growth trend, distribution and market access.

    Science.gov (United States)

    Leta, Samson; Mesele, Frehiwot

    2014-01-01

    The livestock subsector has an enormous contribution to Ethiopia's national economy and livelihoods of many Ethiopians. The subsector contributes about 16.5% of the national Gross Domestic Product (GDP) and 35.6% of the agricultural GDP. It also contributes 15% of export earnings and 30% of agricultural employment. The livestock subsector currently support and sustain livelihoods for 80% of all rural population. The GDP of livestock related activities valued at 59 billion birr. Ethiopian livestock population trends, distribution and marketing vary considerably across space and time due to a variety of reasons. This study was aimed to assess cattle and shoat population growth trend, distribution and their access to market. Regression analysis was used to assess the cattle and shoat population growth trend and Geographic Information Systems (GIS) techniques were used to determine the spatial distribution of cattle and shoats, and their relative access to market. The data sets used are agricultural census (2001/02) and annual CSA agricultural sample survey (1995/96 to 2012/13). In the past eighteen years, the livestock population namely cattle, sheep and goat grew from 54.5 million to over 103.5 million with average annual increment of 3.4 million. The current average national cattle, sheep and goat population per km(2) are estimated to be 71, 33 and 29 respectively (excluding Addis Ababa, Afar and Somali regions). From the total livestock population the country owns about 46% cattle, 43% sheep and 40% goats are reared within 10 km radius from major livestock market centres and all-weather roads. On the other hand, three fourth of the country's land mass which comprises 15% of the cattle, 20% of the sheep and 21% of goat population is not accessible to market (greater than 30 km from major livestock market centres). It is found that the central highland regions account for the largest share of livestock population and also more accessible to market. Defining the

  19. Grid cells analysis of urban growth using remote sensing and population census data

    Science.gov (United States)

    Bagan, H.; Yamagata, Y.

    2012-12-01

    Urban growth and sprawl have drastically altered the ecosystems and ecosystem services. Urban areas are an increasingly important component of the global environment, yet they remain one of the most challenging areas for conducting research. Remote sensing based information is one of the most important resources to support urban planning and administration in megacities. It is possible to provide the up-to-date information regarding the extent, growth, and physical characteristics of urban land. Remote sensing provides spatially consistent image information that covers broad areas with both high spatial resolution and high temporal frequency. Therefore, remote sensing is an important tool for providing information on urban land-cover characteristics and their changes over time at various spatial and temporal scales. Urban land-use and land-cover changes are linked to socio-economic activities. Urbanization includes both the physical growth of a city and the movement of people to urban areas. As a consequence, it is essential to combine remote sensing derived parameters with socio-economic parameter to analyze the spatial-temporal changes and interaction of both factors. The aim of the research was to use1-km2 grid cells to investigate the spatial and temporal dynamics of urban growth in the world mega cities. The research was conducted in the 50 global cities using Landsat ETM/TM remote sensing imagery from 1985 - 2011, and time series population census data (1-km2 resolution gridded population census data of Japan and 2.5 arc-minute resolutions Gridded Population of the World). First, maximum likelihood classification (MLC) method were used to produce land cover maps by using Landsat images. Then intersect the land cover maps with 1-km2 grid cell maps to represents the proportion of each land cover category within each 1-km2 grid cell. Finally, we combined the proportional land cover maps with gridded population census data on 1-km2 resolution grid cells to

  20. Population Growth and Its Expression in Spatial Built-up Patterns: The Sana’a, Yemen Case Study

    Directory of Open Access Journals (Sweden)

    Gunter Zeug

    2010-04-01

    Full Text Available In light of rapid global urbanisation, monitoring and mapping of urban and population growth is of great importance. Population growth in Sana’a was investigated for this reason. The capital of the Republic of Yemen is a rapidly growing middle sized city where the population doubles almost every ten years. Satellite data from four different sensors were used to explore urban growth in Sana’a between 1989 and 2007, assisted by topographic maps and cadastral vector data. The analysis was conducted by delineating the built-up areas from the various optical satellite data, applying a fuzzy-rule-based composition of anisotropic textural measures and interactive thresholding. The resulting datasets were used to analyse urban growth and changes in built-up density per district, qualitatively as well as quantitatively, using a geographic information system. The built-up area increased by 87 % between 1989 and 2007. Built-up density has increased in all areas, but particularly in the northern and southern suburban districts, also reflecting the natural barrier of surrounding mountain ranges. Based on long-term population figures, geometric population growth was assumed. This hypothesis was used together with census data for 1994 and 2004 to estimate population figures for 1989 and 2007, resulting in overall growth of about 240%. By joining population figures to district boundaries, the spatial patterns of population distribution and growth were examined. Further, urban built-up growth and population changes over time were brought into relation in order to investigate changes in population density per built-up area. Population densities increased in all districts, with the greatest density change in the peripheral areas towards the North. The results reflect the pressure on the city’s infrastructure and natural resources and could contribute to sustainable urban planning in the city of Sana’a.

  1. APPLICATION OF ELASTICITY ANALYSES AND PERTURBATION SIMULATIONS IN DETERMINING STRESSOR IMPACTS ON POPULATION GROWTH RATE AND EXTINCTION RISK

    Science.gov (United States)

    Population structure and life history strategies are determinants of how populations respond to stressor-induced impairments in individual-level responses, but a consistent and holistic analysis has not been reported. Effects on population growth rate were modeled using five theo...

  2. Development and Environment: An Assessment of Population Growth vis-a-vis Soil Erosion in Nepal

    Directory of Open Access Journals (Sweden)

    Rishikesh Pandey

    2014-05-01

    Full Text Available This paper discusses the environmental myths and narratives prevailing in Nepal in reference to the population growth and soil erosion. Soil erosion is taken as primary element of environmental degradation by the theory of the Himalayan Environmental Degradation (HED. Many myths and narratives were generated by the vested interest groups to develop the HED. Population growth and over exploitation of natural resource were considered as the prominent causes of soil erosion related environmental degradation. The myths and narratives based on the theory of the HED are still influential in development and environmental policy process in Nepal. In this background this paper highlights some of the research findings that are contrary to conventional belief i.e. population growth lead to soil erosion. The paper is based on literature review. The research evidences from both social and natural sciences are entertained. This paper generates alternative thinking to end the hegemony and unquestionable acceptance of the findings of research undertaken by 'Western, White men' as truth; and their recommendations as the 'blue print' solutions. Critics over orthodox environmentalism and neo-Malthusian accounts are made to validate the ‘hybrid knowledge’ generated in this paper. There are evidences that population pressure have promoted soil erosion. However, Himalayan environmental dynamism which is purely a natural process is far more responsible for soil erosion in the Himalaya. Hence, it is suggested that a critical assessment of any ‘facts’ obtained from research should be made before making them the narratives and reflecting them in policy process. DOI: http://dx.doi.org/10.3126/dsaj.v7i0.10442 Dhaulagiri Journal of Sociology and Anthropology Vol. 7, 2013; 173-196

  3. [The decline in the population growth rate--a priority issue in international politics].

    Science.gov (United States)

    Rhein, E

    1994-08-25

    The Third International UN Conference on Population and Development took place in Cairo in early September 1994 with the participation of 200 governments and 1000 nongovernmental organizations to discuss ways of stabilizing world population at the possible lowest level and how industrialized countries could contribute to this effort. As a consequence of the advances in reproductive medicine the use of contraceptives skyrocketed: in 1994 more than half of men and women were using contraception compared to only 5% in 1950. However, the demographic momentum would still increase world population for another 100 years, even if fertility would drop to 2.2 children per couple (compared to 4 children in 1990). Nevertheless, the present generation could be instrumental in deciding whether the world's population will remain around 8 billion or reach 12 billion between 2050 and 2150. Poor countries can no longer afford an annual growth rate of 2-4% while also trying to improve living standards; this would require an economic growth rate of 6-8%. For the control of population growth both a sustainable environmental policy in the North, with rapid transition to renewable energy and recycling, and a more effective population policy in the South are needed. Family planning (FP) is the precondition of stabilization. The global FP outlays are envisioned to double from the 1994 figure of $5 billion to over $10 billion in the year 2000, with donor contributions to increase from 20% to 40% of the total. The US contribution is to double from $500 million by 2000, while the European Commission decided to boost expenditures for FP from DM 30 million in 1994 to DM 600 million by 2000. Japan is also expending $3 billion during this period. Recent promising developments have emerged: national pronatalist policies have diminished sharply and the pronatalist influence of religions has also declined. Political commitment at the highest level is central to a successful population policy as

  4. Reconciling single-species TACs in the North Sea demersal fisheries using the Fcube mixed-fisheries advice framework

    DEFF Research Database (Denmark)

    Ulrich, Clara; Reeves, Stuart A.; Vermard, Youen

    2011-01-01

    be exhausted before the TAC of another, leading to catches of valuable fish that cannot be landed legally. This important issue is, however, usually not quantified and not accounted for in traditional management advice. A simple approach using traditional catch and effort information was developed, estimating...... in the North Sea and shaped into the advice framework. The substantial overquota catches of North Sea cod likely under the current fisheries regimes are quantified, and it is estimated that the single-species management targets for North Sea cod cannot be achieved unless substantial reductions in TACs of all......Single-species management is a cause of discarding in mixed fisheries, because individual management objectives may not be consistent with each other and the species are caught simultaneously in relatively unselective fishing operations. As such, the total allowable catch (TAC) of one species may...

  5. Reproductive value, the stable stage distribution, and the sensitivity of the population growth rate to changes in vital rates

    Directory of Open Access Journals (Sweden)

    Hal Caswell

    2010-09-01

    Full Text Available The population growth rate, or intrinsic rate of increase, measures the potential rate of growth of a population with specified and fixed vital rates.The sensitivity of population growth rate to changes in the vital rates can be written in terms of the stable stage or age distribution and the reproductive value distribution. If the vital rate measures the rate of production of one type of individual by another, then the sensitivity of growth rate is proportional to the reproductive value of the destination type and the representation in the stable stage distribution of the source type. This formal relationship exists in three forms: one limited to age-classified populations, a second that applies to stage- or age-classified populations, and a third that uses matrix calculus. Each uses a different set of formal demographic techniques; together they provide a relationship that beautifully cuts across different types of demographic models.

  6. Crowded growth leads to the spontaneous evolution of semistable coexistence in laboratory yeast populations.

    Science.gov (United States)

    Frenkel, Evgeni M; McDonald, Michael J; Van Dyken, J David; Kosheleva, Katya; Lang, Gregory I; Desai, Michael M

    2015-09-08

    Identifying the mechanisms that create and maintain biodiversity is a central challenge in biology. Stable diversification of microbial populations often requires the evolution of differences in resource utilization. Alternatively, coexistence can be maintained by specialization to exploit spatial heterogeneity in the environment. Here, we report spontaneous diversification maintained by a related but distinct mechanism: crowding avoidance. During experimental evolution of laboratory Saccharomyces cerevisiae populations, we observed the repeated appearance of "adherent" (A) lineages able to grow as a dispersed film, in contrast to their crowded "bottom-dweller" (B) ancestors. These two types stably coexist because dispersal reduces interference competition for nutrients among kin, at the cost of a slower maximum growth rate. This tradeoff causes the frequencies of the two types to oscillate around equilibrium over the course of repeated cycles of growth, crowding, and dispersal. However, further coevolution of the A and B types can perturb and eventually destroy their coexistence over longer time scales. We introduce a simple mathematical model of this "semistable" coexistence, which explains the interplay between ecological and evolutionary dynamics. Because crowded growth generally limits nutrient access in biofilms, the mechanism we report here may be broadly important in maintaining diversity in these natural environments.

  7. Warming, soil moisture, and loss of snow increase Bromus tectorum’s population growth rate

    Directory of Open Access Journals (Sweden)

    Aldo Compagnoni

    2014-01-01

    Full Text Available Abstract Climate change threatens to exacerbate the impacts of invasive species. In temperate ecosystems, direct effects of warming may be compounded by dramatic reductions in winter snow cover. Cheatgrass (Bromus tectorum is arguably the most destructive biological invader in basins of the North American Intermountain West, and warming could increase its performance through direct effects on demographic rates or through indirect effects mediated by loss of snow. We conducted a two-year experimental manipulation of temperature and snow pack to test whether 1 warming increases cheatgrass population growth rate and 2 reduced snow cover contributes to cheatgrass’ positive response to warming. We used infrared heaters operating continuously to create the warming treatment, but turned heaters on only during snowfalls for the snowmelt treatment. We monitored cheatgrass population growth rate and the vital rates that determine it: emergence, survival and fecundity. Growth rate increased in both warming and snowmelt treatments. The largest increases occurred in warming plots during the wettest year, indicating that the magnitude of response to warming depends on moisture availability. Warming increased both fecundity and survival, especially in the wet year, while snowmelt contributed to the positive effects of warming by increasing survival. Our results indicate that increasing temperature will exacerbate cheatgrass impacts, especially where warming causes large reductions in the depth and duration of snow cover.

  8. Optimal resting-growth strategies of microbial populations in fluctuating environments.

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    Nico Geisel

    Full Text Available Bacteria spend most of their lifetime in non-growing states which allow them to survive extended periods of stress and starvation. When environments improve, they must quickly resume growth to maximize their share of limited nutrients. Cells with higher stress resistance often survive longer stress durations at the cost of needing more time to resume growth, a strong disadvantage in competitive environments. Here we analyze the basis of optimal strategies that microorganisms can use to cope with this tradeoff. We explicitly show that the prototypical inverse relation between stress resistance and growth rate can explain much of the different types of behavior observed in stressed microbial populations. Using analytical mathematical methods, we determine the environmental parameters that decide whether cells should remain vegetative upon stress exposure, downregulate their metabolism to an intermediate optimum level, or become dormant. We find that cell-cell variability, or intercellular noise, is consistently beneficial in the presence of extreme environmental fluctuations, and that it provides an efficient population-level mechanism for adaption in a deteriorating environment. Our results reveal key novel aspects of responsive phenotype switching and its role as an adaptive strategy in changing environments.

  9. Nonlinear dynamics in a business-cycle model with logistic population growth

    International Nuclear Information System (INIS)

    Brianzoni, Serena; Mammana, Cristiana; Michetti, Elisabetta

    2009-01-01

    We consider a discrete-time growth model of the Solow type where workers and shareholders have different but constant saving rates and the population growth dynamics is described by the logistic equation able to exhibit complicated dynamics. We show conditions for the resulting system having a compact global attractor and we describe its structure. We also perform a mainly numerical analysis using the critical lines method able to describe the strange attractor and the absorbing area, in order to show how cyclical or complex fluctuations may be produced in a business-cycle model. We study the dynamic behaviour of the model under different ranges of the main parameters, i.e. the elasticity of substitution between the two production factors and the one in the logistic equation (namely μ). We prove the existence of complex dynamics when the elasticity of substitution between production factors drops below one (so that capital income declines) or μ increases (so that the amplitude of movements in the population growth rate increases).

  10. Comparative Analysis of Single-Species and Polybacterial Wound Biofilms Using a Quantitative, In Vivo, Rabbit Ear Model

    Science.gov (United States)

    2012-08-08

    biofilm behavior of mixed-species cultures with dental and periodontal pathogens. PLoS One 5(10): 131–135. 47. Ma H, Bryers JD (2010) Non-invasive method...Comparative Analysis of Single-Species and Polybacterial Wound Biofilms Using a Quantitative, In Vivo, Rabbit Ear Model Akhil K. Seth1*, Matthew R...Northwestern University, Chicago, Illinois, United States of America, 2 Microbiology Branch, US Army Dental and Trauma Research Detachment, Institute of Surgical

  11. Endless urban growth? On the mismatch of population, household and urban land area growth and its effects on the urban debate.

    Science.gov (United States)

    Haase, Dagmar; Kabisch, Nadja; Haase, Annegret

    2013-01-01

    In European cities, the rate of population growth has declined significantly, while the number of households has increased. This increase in the number of households is associated with an increase in space for housing. To date, the effects of both a declining population and decreasing household numbers remain unclear. In this paper, we analyse the relationship between population and household number development in 188 European cities from 1990-2000 and 2000-2006 to the growth of urban land area and per capita living space. Our results support a trend toward decreasing population with simultaneously increasing household number. However, we also found cites facing both a declining population and a decreasing household number. Nevertheless, the urban land area of these "double-declining" cities has continued to spread because the increasing per capita living space counteracts a reduction in land consumption. We conclude that neither a decline in population nor in household number "automatically" solve the global problem of land consumption.

  12. Linking individual phenotype to density-dependent population growth: the influence of body size on the population dynamics of malaria vectors

    NARCIS (Netherlands)

    Russell, T.L.; Lwetoijera, D.W.; Knols, B.G.J.; Takken, W.; Killeen, G.F.; Ferguson, H.M.

    2011-01-01

    Understanding the endogenous factors that drive the population dynamics of malaria mosquitoes will facilitate more accurate predictions about vector control effectiveness and our ability to destabilize the growth of either low- or high-density insect populations. We assessed whether variation in

  13. Linking individual phenotype to density-dependent population growth: the influence of body size on the population dynamics of malaria vectors

    NARCIS (Netherlands)

    Russell, T.L.; Lwetoijera, D.W.; Knols, B.G.J.; Takken, W.; Killeen, G.F.; Ferguson, H.M.

    2011-01-01

    Understanding the endogenous factors that drive the population dynamics of malaria mosquitoes will facilitate more accurate predictions about vector control effectiveness and our ability to destabilize the growth of either low-or high-density insect populations. We assessed whether variation in

  14. A fuzzy mathematical model of West Java population with logistic growth model

    Science.gov (United States)

    Nurkholipah, N. S.; Amarti, Z.; Anggriani, N.; Supriatna, A. K.

    2018-03-01

    In this paper we develop a mathematics model of population growth in the West Java Province Indonesia. The model takes the form as a logistic differential equation. We parameterize the model using several triples of data, and choose the best triple which has the smallest Mean Absolute Percentage Error (MAPE). The resulting model is able to predict the historical data with a high accuracy and it also able to predict the future of population number. Predicting the future population is among the important factors that affect the consideration is preparing a good management for the population. Several experiment are done to look at the effect of impreciseness in the data. This is done by considering a fuzzy initial value to the crisp model assuming that the model propagates the fuzziness of the independent variable to the dependent variable. We assume here a triangle fuzzy number representing the impreciseness in the data. We found that the fuzziness may disappear in the long-term. Other scenarios also investigated, such as the effect of fuzzy parameters to the crisp initial value of the population. The solution of the model is obtained numerically using the fourth-order Runge-Kutta scheme.

  15. Climate Effects on Growth, Body Condition, and Survival Depend on the Genetic Characteristics of the Population.

    Science.gov (United States)

    Romero-Diaz, Cristina; Breedveld, Merel C; Fitze, Patrick S

    2017-11-01

    Climatic change is expected to affect individual life histories and population dynamics, potentially increasing vulnerability to extinction. The importance of genetic diversity has been highlighted for adaptation and population persistence. However, whether responses of life-history traits to a given environmental condition depend on the genetic characteristics of a population remains elusive. Here we tested this hypothesis in the lizard Zootoca vivipara by simultaneously manipulating habitat humidity, a major climatic predictor of Zootoca's distribution, and adult male color morph frequency, a trait with genome-wide linkage. Interactive effects of humidity and morph frequency had immediate effects on growth and body condition of juveniles and yearlings, as well as on adult survival, and delayed effects on offspring size. In yearlings, higher humidity led to larger female body size and lower humidity led to higher male compared to female survival. In juveniles and yearlings, some treatment effects were compensated over time. The results show that individual responses to environmental conditions depend on the population's color morph frequency, age class, and sex and that these affect intra- and inter-age class competition. Moreover, humidity affected the competitive environment rather than imposing trait-based selection on specific color morphs. This indicates that species' responses to changing environments (e.g., to climate change) are highly complex and difficult to accurately reconstruct and predict without information on the genetic characteristics and demographic structure of populations.

  16. Human population growth offsets climate-driven increase in woody vegetation in sub-Saharan Africa.

    Science.gov (United States)

    Brandt, Martin; Rasmussen, Kjeld; Peñuelas, Josep; Tian, Feng; Schurgers, Guy; Verger, Aleixandre; Mertz, Ole; Palmer, John R B; Fensholt, Rasmus

    2017-03-06

    The rapidly growing human population in sub-Saharan Africa generates increasing demand for agricultural land and forest products, which presumably leads to deforestation. Conversely, a greening of African drylands has been reported, but this has been difficult to associate with changes in woody vegetation. There is thus an incomplete understanding of how woody vegetation responds to socio-economic and environmental change. Here we used a passive microwave Earth observation data set to document two different trends in land area with woody cover for 1992-2011: 36% of the land area (6,870,000 km 2 ) had an increase in woody cover largely in drylands, and 11% had a decrease (2,150,000 km 2 ), mostly in humid zones. Increases in woody cover were associated with low population growth, and were driven by increases in CO 2 in the humid zones and by increases in precipitation in drylands, whereas decreases in woody cover were associated with high population growth. The spatially distinct pattern of these opposing trends reflects, first, the natural response of vegetation to precipitation and atmospheric CO 2 , and second, deforestation in humid areas, minor in size but important for ecosystem services, such as biodiversity and carbon stocks. This nuanced picture of changes in woody cover challenges widely held views of a general and ongoing reduction of the woody vegetation in Africa.

  17. Endogenous Population Dynamics and Economic Growth with Free Trade between Countries

    Directory of Open Access Journals (Sweden)

    Wei-Bin Zhang

    2016-05-01

    Full Text Available This paper builds a model to deal with dynamic interdependence between different countries' birth rates, mortality rates, populations, wealth accumulation, and time distributions between working, leisure and children caring. The model shows the role of human capital, technological and preference changes on national differences in birth rates, mortality rates, time distributions, population change, and wealth accumulation. The economic mechanisms of wealth accumulation, production and trade are based the Solow growth model and the Oniki-Uzawa trade model. We use the utility function proposed by Zhang to describe the behavior of households. We model national and gender differences in human capital, propensity to have children, propensity to use leisure time, and children caring efficiency. We describe the dynamics of global economic growth, trade patterns, national differences in wealth, income, birth rates, mortality rates, and populations with differential equations. We simulate the model to show the motion of the system and identify the existence of equilibrium point. We also examine the effects of changes in the propensity to have children, the propensity to save, woman's propensity to use leisure, woman's human capital, and woman's emotional involvement in children caring on the dynamics of the global and national economies.

  18. The world energy production, consumption and productivity in the energy sector, population and the per capita growth: Regression analysis

    OpenAIRE

    Josheski, Dushko; Lazarov, Darko; Koteski, Cane; Sovreski, Zlatko

    2011-01-01

    In this paper was investigated the relationship between GDP per capita growth and Log of energy production, energy consumption per capita, the log of productivity in energy sector and population. Data covered sample for 220 countries and world regions, years covered from 1980 to 2002.The results showed that if energy consumption increases by 1% GDP per capita growth will decline by 0,57%, if energy production will rise by 1% growth will rise by 1,51%, if population rise by 1% growth will decl...

  19. Long-term growth of Desert Tortoises (Gopherus agassizii) in a southern Nevada population

    Science.gov (United States)

    Medica, P.A.; Nussear, Kenneth E.; Esque, Todd C.; Saethre, Mary B.

    2012-01-01

    Knowledge of growth rates, age at maturity, and longevity are important aspects of a species life history and are directly applicable to life table creation and population viability analyses. We measured the growth of a cohort of 17 semi-wild Desert Tortoises (Gopherus agassizii) located in Rock Valley, Nevada over a 47-yr period beginning in 1963. The tortoises were initially marked as hatchling and juvenile animals between the years 1963 and 1965 and ranged in size from 47 to 77 mm in plastron length. We assigned ages of 1-4 yr to the tortoises at initial capture based on their body size. These tortoises were recaptured, measured, and weighed approximately annually since their initial capture. Growth of male and female tortoises did not differ significantly until animals reached the age of 23-25 yr. Annual tortoise growth was correlated with the production of ephemeral vegetation, while accounting for size, sex, and repeated measurements of the animals as well as the interval between measurements. However, the production of ephemeral plants was likewise highly correlated (non-linearly) with winter rainfall. Stochastic predation events between 2003 and 2007 decimated this cohort of tortoises. The average age of the long-term surviving tortoises from this cohort was 43 yr with a range of 39-47 yr. Twelve of the tortoises survived to the age of 39 yr and 11 of the 12 reached 40 yr.

  20. The growth and population dynamics of seagrass Thalassia hemprichii in Suli Waters, Ambon Island

    Science.gov (United States)

    Tupan, C. I.; Uneputty, Pr A.

    2017-10-01

    The objectives of the research were to determined growth of rhizome, age structure, recruitment rate, and mortality rate of Thalassia hemprichii. Data were collected by using reconstruction technique which the measurements were based on past growth history. The age of seagrass was based on plastochrone interval. The recruitment rate was estimated by age structure of living shoots while mortality rate was estimated by age structure of dead shoots. The research was conducted on coastal waters of Suli where divided into two stations with different substrates, namely mixed substrates of sand and mud (S1) and mixed substrates of sand and coral fragment (S2). The growth rate of horizontal rhizome ranged from 4.15-8.68 cm.year-1 whereas the growth rate of vertical rhizome was 1.11-1.16 cm.year-1. The average age of T. hemprichii varied between 3.22-4.15 years. The youngest shoots were found at age 0.38 years and the oldest shoots were 7.82 years. Distribution of age was polymodal which reflecting cohort. The recruitment rate ranged from 0.23-0.54 year-1. Otherwise, the mortality rate ranged from 0.21-0.26 year-1.Seagrass population of T. hemprichii in Suli Waters indicated an increasing condition which shown by higher recruitment rate than mortality rate.

  1. Density regulation in Northeast Atlantic fish populations: Density dependence is stronger in recruitment than in somatic growth.

    Science.gov (United States)

    Zimmermann, Fabian; Ricard, Daniel; Heino, Mikko

    2018-01-30

    Population regulation is a central concept in ecology, yet in many cases its presence and the underlying mechanisms are difficult to demonstrate. The current paradigm maintains that marine fish populations are predominantly regulated by density-dependent recruitment. While it is known that density-dependent somatic growth can be present too, its general importance remains unknown and most practical applications neglect it. This study aimed to close this gap by for the first time quantifying and comparing density dependence in growth and recruitment over a large set of fish populations. We fitted density-dependent models to time-series data on population size, recruitment and age-specific weight from commercially exploited fish populations in the Northeast Atlantic Ocean and the Baltic Sea. Data were standardized to enable a direct comparison within and among populations, and estimated parameters were used to quantify the impact of density regulation on population biomass. Statistically significant density dependence in recruitment was detected in a large proportion of populations (70%), whereas for density dependence in somatic growth the prevalence of density dependence depended heavily on the method (26% and 69%). Despite age-dependent variability, the density dependence in recruitment was consistently stronger among age groups and between alternative approaches that use weight-at-age or weight increments to assess growth. Estimates of density-dependent reduction in biomass underlined these results: 97% of populations with statistically significant parameters for growth and recruitment showed a larger impact of density-dependent recruitment on population biomass. The results reaffirm the importance of density-dependent recruitment in marine fishes, yet they also show that density dependence in somatic growth is not uncommon. Furthermore, the results are important from an applied perspective because density dependence in somatic growth affects productivity and

  2. Non-occupational exposure to paint fumes during pregnancy and fetal growth in a general population

    DEFF Research Database (Denmark)

    Sørensen, Mette; Andersen, Anne-Marie N; Raaschou-Nielsen, Ole

    2010-01-01

    Occupational exposure to organic solvents during pregnancy has been associated with reduced fetal growth. Though organic solvents in the form of paint fumes are also found in the home environment, no studies have investigated the effect of such exposure in a general population. We studied...... associations between residential exposure to paint fumes during pregnancy and fetal growth within the Danish National Birth Cohort which consecutively recruited pregnant women from 1996 to 2002 from all over Denmark. Around the 30th pregnancy week, 19,000 mothers were interviewed about use of paint...... in their residence during pregnancy. The mothers were also asked about smoking habits and alcohol consumption during pregnancy, pre-pregnancy weight, height, parity and occupation. Information on birth weight and gestational age was obtained from national registers. We found that 45% of the mothers had been exposed...

  3. Local population extinction and vitality of an epiphytic lichen in fragmented old-growth forest.

    Science.gov (United States)

    Ockinger, Erik; Nilsson, Sven G

    2010-07-01

    The population dynamics of organisms living in short-lived habitats will largely depend on the turnover of habitat patches. It has been suggested that epiphytes, whose host plants can be regarded as habitat patches, often form such patch-tracking populations. However, very little is known about the long-term fate of epiphyte individuals and populations. We estimated life span and assessed environmental factors influencing changes in vitality, fertility, abundance, and distribution of the epiphytic lichen species Lobaria pulmonaria on two spatial scales, individual trees and forest patches, over a period of approximately 10 years in 66 old-growth forest fragments. The lichen had gone extinct from 7 of the 66 sites (13.0%) where it was found 10 years earlier, even though the sites remained unchanged. The risk of local population extinction increased with decreasing population size. In contrast to the decrease in the number of occupied trees and sites, the mean area of the lichen per tree increased by 43.0%. The number of trees with fertile ramets of L. pulmonaria increased from 7 (approximately 1%) to 61 (approximately 10%) trees, and the number of forest fragments with fertile ramets increased from 4 to 23 fragments. The mean annual rate of L. pulmonaria extinction at the tree level was estimated to be 2.52%, translating into an expected lifetime of 39.7 years. This disappearance rate is higher than estimated mortality rates for potential host trees. The risk of extinction at the tree level was significantly positively related to tree circumference and differed between tree species. The probability of presence of fertile ramets increased significantly with local population size. Our results show a long expected lifetime of Lobaria pulmonaria ramets on individual trees and a recent increase in vitality, probably due to decreasing air pollution. The population is, however, declining slowly even though remaining stands are left uncut, which we interpret as an

  4. Prevalence of Epidermal Growth Factor Receptor Mutations in Patients with Non-Small Cell Lung Cancer in Turkish Population.

    Science.gov (United States)

    Güler Tezel, Gaye; Şener, Ebru; Aydın, Çisel; Önder, Sevgen

    2017-12-01

    Epidermal growth factor receptor mutation analysis in non-small cell lung cancer is important for selecting patients who will receive treatment with tyrosine kinase inhibitors. In this study, we aimed to investigate the prevalence of epidermal growth factor receptor mutations and mutation patterns in the Turkish population. We retrospectively reviewed molecular pathology reports of 959 cases with lung cancer analysed for epidermal growth factor receptor mutations. We analysed all four epidermal growth factor receptor exon mutations using a real-time polymerase chain reaction platform. In this study, the epidermal growth factor receptor mutation rate in the Turkish population was 16.7% (160 of 959). The epidermal growth factor receptor mutation frequency was significantly higher in women (37.1%, n=96) than in men (9.1%, n=64) (pmutation rate was higher in the adenocarcinoma histologic type (pmutations were older than those without mutations (p=0.003). The most frequent mutations were exon 19 deletions (48.8%, 78/160) and exon 21 L858R point mutations (38.1.1%, 61/160). We also detected compound mutation patterns in three cases (1.9%). The prevalence of epidermal growth factor receptor mutations in the Turkish population was slightly higher than that in the Caucasian population and lower than that in the East Asian population. The results of this study may provide guidance in personalized therapy of non-small cell lung cancer in the Turkish population.

  5. Insulin-like growth factor I and anthropometric parameters in a Danish population

    DEFF Research Database (Denmark)

    Friedrich, N; Jørgensen, Torben; Juul, A

    2012-01-01

    During the last decade several studies indicated that low insulin-like growth factor (IGF) I levels are related to higher risk of cardiovascular disease and mortality. Obesity represents one further main cardiovascular risk factor which might also be related to IGF-I. The objective of the present...... study was to analyse the associations between anthropometric measures and IGF-I levels in a population-based sample. From the Danish cross-sectional Health2006 study 3,328 subjects (1,835 women; 1,493 men) aged 19-72 years were included in the analyses. Serum IGF-I levels were determined...

  6. [A model of world population growth as an experiment in systematic research].

    Science.gov (United States)

    Kapitsa, S

    1997-01-01

    A mathematical model was developed for the estimation of global population growth, and the estimates were compared with those of the UN and covered the stretch of 4.4 million years B.C. to the years 2175 and 2500 A.D. The estimates were also broken down into human, geological, and technological historical periods. The model showed that human population would stabilize at the level of 14 billion around 2500 A.D. and 13 billion around 2200 A.D., in accordance with UN projections. It also revealed the history of human population growth through the following stages (UN figures are listed in parentheses): 100,000, about 1.6 million years ago; 5 (1-5) million, 35,000 B.C.; 21 (10-15) million, 7000 B.C.; 46 (47) million, 2000 B.C.; 93 (100-230) million, at the time of Christ; 185 (275-345) million, 1000 A.D.; 366 (450-540) million, 1500 A.D.; 887 (907) million, 1800 A.D.; 1158 (1170) million, 1850 A.D.; 1656 (1650-1710) million, 1900 A.D.; 2812 (2515) million, 1950 A.D.; 5253 (5328) million, 1990 A.D.; 6265 (6261) million, 2000 A.D.; 10,487 (10,019) million, 2050 A.D.; 12,034 (11,186) million, 2100 A.D.; 12,648 (11,543) million, 2150 A.D.; 12,946 (11,600) million, 2200 A.D.; and 13,536 million, 2500 A.D. The model advanced the investigation of phenomena by studying the interactions between economical, technological, social, cultural, and biological processes. The analysis showed that humanity has reached a critical phase in its growth and that development in each period depended on external, not internal, factors. This permits the formulation of the principle of demographic imperative (distinct from the Malthusian principle), which states that resources determine the speed and extent of the growth of population.

  7. Climate change and population growth in Timor Leste: implications for food security.

    Science.gov (United States)

    Molyneux, Nicholas; da Cruz, Gil Rangel; Williams, Robert L; Andersen, Rebecca; Turner, Neil C

    2012-12-01

    The climate in Timor Leste (East Timor) is predicted to become about 1.5 °C warmer and about 10 % wetter on average by 2050. By the same year, the population is expected to triple from 1 to 2.5-3 million. This article maps the predicted changes in temperature and rainfall and reviews the implications of climate change and population growth on agricultural systems. Improved cultivars of maize, rice, cassava, sweet potato and peanuts with high yield performance have been introduced, but these will need to be augmented in the future with better adapted cultivars and new crops, such as food and fodder legumes and new management practices. The requirements for fertilizers to boost yields and terracing and/or contour hedgerows to prevent soil erosion of steeply sloping terrain are discussed. Contour hedges can also be used for fodder for improved animal production to provide protein to reduce malnutrition.

  8. Contributions of vital rates to growth of a protected population of American black bears

    Science.gov (United States)

    Mitchell, M.S.; Pacifici, L.B.; Grand, J.B.; Powell, R.A.

    2009-01-01

    Analyses of large, long-lived animals suggest that adult survival generally has the potential to contribute more than reproduction to population growth rate (??), but because survival varies little, high variability in reproduction can have a greater influence. This pattern has been documented for several species of large mammals, but few studies have evaluated such contributions of vital rates to ?? for American black bears (Ursus americanus). We used variance-based perturbation analyses (life table response experiments, LTRE) and analytical sensitivity and elasticity analyses to examine the actual and potential contributions of variation of vital rates to variation in growth rate (??) of a population of black bears inhabiting the Pisgah Bear Sanctuary in the southern Appalachian Mountains of North Carolina, using a 22-year dataset. We found that recruitment varied more than other vital rates; LTRE analyses conducted over several time intervals thus indicated that recruitment generally contributed at least as much as juvenile and adult survival to observed variation in ??, even though the latter 2 vital rates had the greater potential to affect ??. Our findings are consistent with predictions from studies on polar bears (U. maritimus) and grizzly bears (U. arctos), but contrast with the few existing studies on black bears in ways that suggest levels of protection from human-caused mortality might explain whether adult survival or recruitment contribute most to variation in ?? for this species. We hypothesize that ?? is most strongly influenced by recruitment in protected populations where adult survival is relatively high and constant, whereas adult survival will most influence ?? for unprotected populations. ?? 2009 International Association for Bear Research and Management.

  9. Population growth and development in the Third World: the neocolonial context.

    Science.gov (United States)

    Patterson, J G; Shrestha, N R

    1988-01-01

    Less developed countries (LDCs) that were colonies of other nations continued operating under the same social and political structures set up by the former ruling nations. The small minority of elites in the LDCs held on to the power acquired during colonial times. In order to preserve their political and financial status after independence, they maintained their close linkages to the capitalist nations and their multinational corporations (MNCs). The elites did not generally have popular support, however. These capitalist nations and their commercial interests continue to dictate most LDCs development process which supports the financial interests of the MNCs and the local elites and not those of the majority, the poor. The poor realize that they are trapped and unable to break away from the economic and political structures, therefore, to assure some form of security, they have many children which exacerbates their poverty. Yet population control policies based on Malthusian theory and those that rely on such undimensional, technical approaches as family planning alone cannot cure the multidimensional social problems of high population growth and poverty. Neither the Malthusian nor Marxist theories totally explain the situation in the LDCs or even provide workable solutions. Research on population and development in LDCs needs to address both the Malthusian concern for the problems posed by high growth rates and the Marxist critique of class struggle in development trends. To eliminate the trap of poverty and dependent economies, each country must design its own remedies based on its history, culture, and geography and alter the prevailing social, economic, and political power structures in favor of the poor. 6 propositions that must be modified to each nation's particular problems and needs are presented to guide LDCs in formulating or reformulating policies to alleviate the problems of population and poverty.

  10. Bait stations, hard mast, and black bear population growth in Great Smoky Mountains National Park

    Science.gov (United States)

    Clark, Joseph D.; van Manen, Frank T.; Pelton, Michael R.

    2005-01-01

    Bait-station surveys are used by wildlife managers as an index to American black bear (Ursus americanus) population abundance, but the relationship is not well established. Hard mast surveys are similarly used to assess annual black bear food availability which may affect mortality and natality rates. We used data collected in Great Smoky Mountains National Park (GSMNP) from 1989 to 2003 to determine whether changes in the bait-station index (ΔBSI) were associated with estimated rates of bear population growth (λ) and whether hard mast production was related to bear visitation to baits. We also evaluated whether hard mast production from previous years was related to λ. Estimates of λ were based on analysis of capture-recapture data with the Pradel temporal symmetry estimator. Using the Akaike's Information Criterion (AIC), our analysis revealed no direct relationship between ΔBSI and λ. A simulation analysis indicated that our data were adequate to detect a relationship had one existed. Model fit was marginally improved when we added total oak mast production of the previous year as an interaction term suggesting that the BSI was confounded with environmental variables. Consequently the utility of the bait-station survey as a population monitoring technique is questionable at the spatial and temporal scales we studied. Mast survey data, however, were valuable covariates of λ. Population growth for a given year was negatively related to oak mast production 4 and 5 years prior. That finding supported our hypothesis that mast failures can trigger reproductive synchrony, which may not be evident from the trapped sample until years later.

  11. Ethnic differences in fetal size and growth in a multi-ethnic population.

    Science.gov (United States)

    Sletner, Line; Rasmussen, Svein; Jenum, Anne Karen; Nakstad, Britt; Jensen, Odd Harald Rognerud; Vangen, Siri

    2015-09-01

    Impaired or excessive fetal growth is associated with adverse short- and long-term health outcomes that differ between ethnic groups. We explored ethnic differences in fetal size and growth from mid pregnancy until birth. Data are from the multi-ethnic STORK-Groruddalen study, a population-based, prospective cohort of 823 pregnant women and their offspring in Oslo, Norway. Measures were z-scores of estimated fetal weight (EFW), head circumference (HC), abdominal circumference (AC) and femur length (FL), in gestational week 24, 32 and 37, measured by ultrasound, and similar measures at birth. Differences in fetal size and growth were assessed using separate Linear Mixed Models including all four time points, with ethnic Europeans as reference. In week 24 South Asian fetuses had smaller AC, but larger FL than Europeans, and slightly lower EFW (-0.17 SD (-0.33, -0.01), p=0.04). Middle East/North African fetuses also had larger FL, but similar AC, and hence slightly higher EFW (0.18 (0.003, 0.36), p=0.05). Both groups had slower growth of AC, FL and EFW from this time until birth, and had -0.61 SD (-0.73, -0.49) and -0.28 SD (-0.41, -0.15) lower birth weight respectively. Ethnic East Asians, on the other hand, were smaller throughout pregnancy and had -0.58 SD (-0.82, -0.34) lower birth weight. Significant ethnic differences remained after adjusting for maternal factors. We observed ethnic differences in fetal size and body proportions already in gestational week 24, and in fetal growth from this time until birth, which were only partly explained by key maternal factors. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. A method for analyzing changing prison populations: explaining the growth of the elderly in prison.

    Science.gov (United States)

    Luallen, Jeremy; Kling, Ryan

    2014-12-01

    For the past several decades, the U.S. prison system has witnessed a steady and persistent increase in the ages of prison populations. Given the additional costs and burdens placed on prisons as they house older inmates, this aging trend has generated intense interest among policy makers and academics who seek to understand why prison populations are getting older. This article presents a method for evaluating drivers influencing the change in age distributions among prisoners. We define a methodological approach and demonstrate its application using prison data from four states reporting to the Bureau of Justice Statistics' National Corrections Reporting Program. We find that since 2000, the primary driver of overall growth in the elderly populations in prison (defined as inmates over 50) is the increasing admission age of offenders entering prison. Moreover, changes in offense mix and sentence length/time served over the last decade have had significantly less influence on the age composition of prison populations. We also find that the impact of explanatory factors varies across states and offense types. For example, prison admission and exit rates explain much of the change in elderly drug offenders in New York, but not elderly violent offenders, where admission age plays a much stronger explanatory role. Our analysis offers an effective demonstration that supports the use of this method as an important and informative first step toward understanding components of change that affect the problem of prison aging. © The Author(s) 2014.

  13. Influence of packaging conditions on natural microbial population growth of endive.

    Science.gov (United States)

    Charles, Florence; Rugani, Nathalie; Gontard, Nathalie

    2005-05-01

    The influence of three packaging conditions, i.e., unmodified atmosphere packaging (UAP), passive modified atmosphere packaging (MAP), and active MAP, on the natural microbial population growth of endive was investigated at 20 degrees C. For UAP, endive was placed in macroperforated oriented polypropylene pouches that maintained gas composition close to that of air (21 kPa O2 and 0 kPa CO2) but also limited superficial product dehydration. For MAP, endive was placed in low-density polyethylene pouches that induced a 3 kPa O2 and 5 kPa CO2 equilibrium atmosphere composition. Steady state was reached after 25 h of storage with an oxygen absorbing packet (active MAP) compared with 100 h without the packet (passive MAP) and was maintained for 200 h. After 312 h of storage, both active and passive MAP reduced total aerobic mesophile, yeast, and mold population growth compared with endive in UAP. Active MAP accelerated and improved the inhibition of Pseudomonas spp. and Enterobacteriaceae, respectively, probably because of the rapid O2 depletion during the transition period. A shift in the Enterobacteriaceae subpopulation from Rhanella aquatilis to Enterobacter agglomerans was observed for both passive and active MAP.

  14. The impact of population ageing on the social security expenditure and economic growth in Japan.

    Science.gov (United States)

    Maruo, N

    1987-05-01

    The author considers the impact of demographic aging in Japan on the social security system and on economic growth. It is argued that "First of all, as the cost of social security (including social services) increases remarkably at the earlier stage of ageing, the disposable (after tax) income and private consumption of the present labour force generation tend to increase at a lower growth rate than that of the GNP....Secondly if pension systems are based on terminal funding schemes, the ageing of the population increases savings (net increase of the amount of the pension funds) at the earlier stage of the ageing of the population. Thirdly, there is a time lag between the increase of social security benefits and the decrease in the personal savings ratio. The high ratio of savings and the shortage of aggregate demand as well as the high pressure for export in...recent Japan can partly be attributed to the above factors." Possible future economic scenarios as demographic ageing in Japan proceeds are described, and policies to avert anticipated problems are outlined. (SUMMARY IN JPN) excerpt

  15. Spiking, Bursting, and Population Dynamics in a Network of Growth Transform Neurons.

    Science.gov (United States)

    Gangopadhyay, Ahana; Chakrabartty, Shantanu

    2017-04-27

    This paper investigates the dynamical properties of a network of neurons, each of which implements an asynchronous mapping based on polynomial growth transforms. In the first part of this paper, we present a geometric approach for visualizing the dynamics of the network where each of the neurons traverses a trajectory in a dual optimization space, whereas the network itself traverses a trajectory in an equivalent primal optimization space. We show that as the network learns to solve basic classification tasks, different choices of primal-dual mapping produce unique but interpretable neural dynamics like noise shaping, spiking, and bursting. While the proposed framework is general enough, in this paper, we demonstrate its use for designing support vector machines (SVMs) that exhibit noise-shaping properties similar to those of ΣΔ modulators, and for designing SVMs that learn to encode information using spikes and bursts. It is demonstrated that the emergent switching, spiking, and burst dynamics produced by each neuron encodes its respective margin of separation from a classification hyperplane whose parameters are encoded by the network population dynamics. We believe that the proposed growth transform neuron model and the underlying geometric framework could serve as an important tool to connect well-established machine learning algorithms like SVMs to neuromorphic principles like spiking, bursting, population encoding, and noise shaping.

  16. Elasticity of population growth with respect to the intensity of biotic or abiotic driving factors.

    Science.gov (United States)

    Lee, Charlotte T

    2017-04-01

    Demographic analysis can elucidate how driving factors, such as climate or species interactions, affect populations. One important question is how growth would respond to future changes in the mean intensity of a driving factor or in its variability, such as might be expected in a fluctuating and shifting climate. Here I develop an approach to computing new stochastic elasticities to address this question. The linchpin of this novel approach is the multidimensional demographic difference that expresses how a population responds to change in the driving factor between two discrete levels of intensity. I use this difference to design a perturbation matrix that links data from common empirical sampling schemes with rigorous theory for stochastic elasticities. Although the starting point is a difference, the products of this synthesis are true derivatives: they are elasticity with respect to the mean intensity of a driving factor, and elasticity with respect to variability in a driving factor. Applying the methods to published data, I demonstrate how these new elasticities can shed light on growth rate response within and at the boundary of the previously observed range of the driving factor, thus helpfully indicating nonlinearity in the observed and in the potential future response. The stochastic approach simplifies in a fixed environment, yielding a compact formula for deterministic elasticity to a driving factor. © 2017 by the Ecological Society of America.

  17. Elephant population growth in Kruger National Park, South Africa, under a landscape management approach

    Directory of Open Access Journals (Sweden)

    Sam M. Ferreira

    2017-08-01

    Full Text Available South African National Parks (SANParks manage landscapes rather than numbers of elephants (Loxodonta africana to mitigate the effects that elephants may have on biodiversity, tourism and stakeholder conservation values associated with protected areas. This management philosophy imposes spatial variability of critical resources on elephants. Restoration of such ecological processes through less intensive management predicts a reduction in population growth rates from the eras of intensive management. We collated aerial survey data since 1995 and conducted an aerial total count using a helicopter observation platform during 2015. A minimum of 17 086 elephants were resident in the Kruger National Park (KNP in 2015, growing at 4.2% per annum over the last generation of elephants (i.e. 12 years, compared to 6.5% annual population growth noted during the intensive management era ending in 1994. This may come from responses of elephants to density and environmental factors manifested through reduced birth rates and increased mortality rates. Authorities should continue to evaluate the demographic responses of elephants to landscape scale interventions directed at restoring the limitation of spatial variance in resource distribution on elephant spatiotemporal dynamics and the consequences that may have for other conservation values. Conservation implications: Conservation managers should continue with surveying elephants in a way that allows the extraction of key variables. Such variables should focus on measures that reflect on how theory predicts elephants should respond to management interventions.

  18. Characterization of Saccharomyces cerevisiae natural populations for pseudohyphal growth and colony morphology.

    Science.gov (United States)

    Casalone, Enrico; Barberio, Claudia; Cappellini, Lorenzo; Polsinelli, Mario

    2005-03-01

    In this work we have analyzed the colony and cellular morphologies of natural populations of Saccharomyces cerevisiae strains in response to different environmental stimuli. Among one thousand strains grown on YPD medium, 2.5% exhibited a rough (R) colony phenotype versus a smooth (S) phenotype. When grown on the ammonium-deficient medium SLAD, 56% of the strains showed a filamentous phenotype, often associated (43.8%) with an invasive phenotype, while 4.7% of the strains exhibited only an invasive phenotype. The rough phenotype on YPD was always associated with the filamentous phenotype on SLAD. A subset of 52 strains was further characterized for the growth phenotype under different stimuli (nitrogen deprivation, addition of alcohols, growth on proline as sole nitrogen source). On 27 strains, genetic analysis of the spore products was also performed. The entire set of data showed a wide distribution of dimorphism in the yeast population and great variability with respect to the dimorphic switch capability. Some strains grew with peculiar colony morphologies under different environmental stimuli and some showed colony morphology variations. Ecological implications of the wide spreading of dimorphic behavior and the occurrence of peculiar colony morphologies in natural yeasts are discussed.

  19. Identification of QTLs for shoot and root growth under ionic-osmotic stress in Lotus, using a RIL population

    DEFF Research Database (Denmark)

    Quero, Gastón; Gutíerrez, Lucía; Lascano, Ramiro

    2014-01-01

    The genus Lotus includes a group of forage legume species including genotypes of agronomic interest and model species. In this work, an experimental hydroponic growth system allowed the discrimination of growth responses to ionic-osmotic stress in a population of recombinant inbred lines (RILs...

  20. Population growth rate and genetic variability of small and large populations of Red flour beetle (Tribolium castaneum) following multigenerational exposure to copper.

    Science.gov (United States)

    Laskowski, Ryszard; Radwan, Jacek; Kuduk, Katarzyna; Mendrok, Magdalena; Kramarz, Paulina

    2015-07-01

    We reared large (1000 individuals) and small (20 individuals) populations of Tribolium castaneum on diet contaminated with copper in order to determine if the size of a population affects its ability to adapt to adverse environmental conditions. After 10 generations, we used microsatellite markers to estimate and subsequently compare the genetic variability of the copper-treated populations with that of the control populations, which were reared on uncontaminated medium. Additionally, we conducted a full cross-factorial experiment which evaluated the effects of 10 generations of "pre-exposure" to copper on a population's fitness in control and copper-contaminated environments. In order to distinguish results potentially arising from genetic adaptation from those due to non-genetic effects associated to parental exposure to copper, we subjected also F11 generation, originating from parents not exposed to copper, to the same cross-factorial experiment. The effects of long-term exposure to copper depended on population size: the growth rates of small populations that were pre-exposed to copper were inhibited compared to those of small populations reared in uncontaminated environments. Large Cu-exposed populations had a higher growth rate in the F10 generation compared to the control groups, while the growth rate of the F11 generation was unaffected by copper exposure history. The only factor that had a significant effect on genetic variability was population size, but this was to be expected given the large difference in the number of individuals between large and small populations. Neither copper contamination nor its interaction with population size affected the number of microsatellite alleles retained in the F10 generation.

  1. 77 FR 1498 - Draft Environmental Assessment and Proposed Single-Species Habitat Conservation Plan for the...

    Science.gov (United States)

    2012-01-10

    ... the potential for ``take'' of one federally listed animal, the Central California Distinct Population..., sacred and traditional areas, and other historic preservation concerns, which are required to be considered in project planning by the National Historic Preservation Act; and 6. Identification of any other...

  2. Morphometry, growth and reproduction of an Atlantic population of the razor clam Ensis macha (Molina, 1782

    Directory of Open Access Journals (Sweden)

    Pedro J. Barón

    2004-06-01

    Full Text Available Ensis macha is a razor clam distributed throughout the coasts of southern Argentina and Chile. Even though it represents a valuable fishery resource, the exploitation of its Atlantic populations has begun only in recent years. This study provides the first estimates of growth rate, an interpretation of the reproductive cycle on the coast of the northern Argentine Patagonia and an analysis of the species morphometry. Growth was estimated by direct observation of growth rings on the valves by two observers. The reproductive cycle was interpreted by the analysis of temporal change of oocyte size frequency distributions. Parameter estimations for the von Bertalanffy equations respectively obtained by observers 1 and 2 were 154 and 153.7 mm for L?, 0.25 and 0.20 yr-1 for k, and -0.08 and -0.72 yr for t0. Two spawning peaks were detected: September-November 1999 and May-June 2000. However, mature females were found all year round. An abrupt change in the relationship between shell length and height was detected at 11.2 mm length.

  3. Non-occupational exposure to paint fumes during pregnancy and fetal growth in a general population.

    Science.gov (United States)

    Sørensen, Mette; Andersen, Anne-Marie N; Raaschou-Nielsen, Ole

    2010-05-01

    Occupational exposure to organic solvents during pregnancy has been associated with reduced fetal growth. Though organic solvents in the form of paint fumes are also found in the home environment, no studies have investigated the effect of such exposure in a general population. We studied associations between residential exposure to paint fumes during pregnancy and fetal growth within the Danish National Birth Cohort which consecutively recruited pregnant women from 1996 to 2002 from all over Denmark. Around the 30th pregnancy week, 19,000 mothers were interviewed about use of paint in their residence during pregnancy. The mothers were also asked about smoking habits and alcohol consumption during pregnancy, pre-pregnancy weight, height, parity and occupation. Information on birth weight and gestational age was obtained from national registers. We found that 45% of the mothers had been exposed to paint fumes in their residence during pregnancy. We found a statistically significant inverse relationship between exposure to paint fumes and the risk of being small for gestational age. There were no statistically significant associations between exposure to paint fumes and birth weight and risk of preterm birth after adjustment for potential confounders. Our results suggest that there are no causal relationship between non-occupational exposure to paint fumes in the residence during pregnancy and fetal growth. Copyright 2010 Elsevier Inc. All rights reserved.

  4. Effect of crop development on biogenic emissions from plant populations grown in closed plant growth chambers

    Science.gov (United States)

    Batten, J. H.; Stutte, G. W.; Wheeler, R. M.

    1995-01-01

    The Biomass Production Chamber at John F. Kennedy Space Center is a closed plant growth chamber facility that can be used to monitor the level of biogenic emissions from large populations of plants throughout their entire growth cycle. The head space atmosphere of a 26-day-old lettuce (Lactuca sativa cv. Waldmann's Green) stand was repeatedly sampled and emissions identified and quantified using GC-mass spectrometry. Concentrations of dimethyl sulphide, carbon disulphide, alpha-pinene, furan and 2-methylfuran were not significantly different throughout the day; whereas, isoprene showed significant differences in concentration between samples collected in light and dark periods. Volatile organic compounds from the atmosphere of wheat (Triticum aestivum cv. Yecora Rojo) were analysed and quantified from planting to maturity. Volatile plant-derived compounds included 1-butanol, 2-ethyl-1-hexanol, nonanal, benzaldehyde, tetramethylurea, tetramethylthiourea, 2-methylfuran and 3-methylfuran. Concentrations of volatiles were determined during seedling establishment, vegetative growth, anthesis, grain fill and senescence and found to vary depending on the developmental stage. Atmospheric concentrations of benzaldehyde and nonanal were highest during anthesis, 2-methylfuran and 3-methylfuran concentrations were greatest during grain fill, and the concentration of the tetramethylurea peaked during senescence.

  5. Effects of probiotic supplement ( and on feed efficiency, growth performance, and microbial population of weaning rabbits

    Directory of Open Access Journals (Sweden)

    Thanh Lam Phuoc

    2017-02-01

    Full Text Available Objective This study aimed to investigate the effects of single or/and double strains of probiotic supplement on feed efficiency, growth performance, and microbial population in distal gastrointestinal tract (GIT of weaning rabbits. Methods Sixty-four weaning (28 days old New Zealand White rabbits were randomly distributed into four groups with treatments including: basal diet without probiotic supplement (control or supplemented as follows: 1×106 cfu/g B. subtilis (BS group, 1×107 cfu/g L. acidophilus (LA group, or 0.5×106 cfu/g B. subtilis plus 0.5×107 cfu/g L. acidophilus (BL group. During the research, the male and female rabbits were fed separately. Body weight of the rabbits was recorded at 28, 42, and 70 d of age. Results There was an increase (p<0.05 in body weight gain for the LA group at 42 d. Rabbits fed BL responsed with a greater growth (p<0.05 and better feed conversion ratio (p<0.05 than those fed with no probiotic. Digestibility coefficients of dry matter, organic matter, crude protein, neutral detergent fiber, and gross energy were higher (p<0.05 in LA and BL groups than those in the control group. Male rabbits had higher (p<0.05 Bacilli spp. and Coliformis spp. in the ileum than female rabbits. Rabbits supplemented with BS had greater (p<0.05 numbers of bacilli in all intestinal segments than those receiving no probiotic, whereas intestinal Lactobacilli populations were greater (p<0.001 in the LA and BL diets compared to control. Average intestinal coliform populations were lowest (p<0.05 in the rabbits supplemented with LA as compared to those fed the control and BS. Conclusion Supplementation of L. acidophilus alone or in combination with B. subtilis at a half of dose could enhance number of gut beneficial bacteria populations, nutrient digestibility, cecal fermentation, feed efficiency, and growth performance, but rabbits receiving only B. subtilis alone were not different from the controls without probiotic.

  6. Population growth of Varroa destructor (Acari: Varroidae) in honey bee colonies is affected by the number of foragers with mites.

    Science.gov (United States)

    DeGrandi-Hoffman, Gloria; Ahumada, Fabiana; Zazueta, Victor; Chambers, Mona; Hidalgo, Geoffrey; deJong, Emily Watkins

    2016-05-01

    Varroa mites are a serious pest of honey bees and the leading cause of colony losses. Varroa have relatively low reproductive rates, so populations should not increase rapidly, but often they do. Other factors might contribute to the growth of varroa populations including mite migration into colonies on foragers from other hives. We measured the proportion of foragers carrying mites on their bodies while entering and leaving hives, and determined its relationship to the growth of varroa populations in those hives at two apiary sites. We also compared the estimates of mite population growth with predictions from a varroa population dynamics model that generates estimates of mite population growth based on mite reproduction. Samples of capped brood and adult bees indicated that the proportion of brood cells infested with mites and adult bees with phoretic mites was low through the summer but increased sharply in the fall especially at site 1. The frequency of capturing foragers with mites on their bodies while entering or leaving hives also increased in the fall. The growth of varroa populations at both sites was not significantly related to our colony estimates of successful mite reproduction, but instead to the total number of foragers with mites (entering and leaving the colony). There were more foragers with mites at site 1 than site 2, and mite populations at site 1 were larger especially in the fall. The model accurately estimated phoretic mite populations and infested brood cells until November when predictions were much lower than those measured in colonies. The rapid growth of mite populations particularly in the fall being a product of mite migration rather than mite reproduction only is discussed.

  7. Some socio-economic aspects of population growth in the USSR.

    Science.gov (United States)

    Simchera, V

    1974-01-01

    This summarizes population trends in the U.S.S.R. since the early 19 00's. On August 9, 1973, the population topped 250 million, almost precisely double that of Russia at the time of the 1st general census in 1897. Since 1922 it had increased by more than 84%. Russia has suffered more population loss in wars than any other country in modern times. The First World War, the Civil War, and the Second World War took a toll of more than 30 million, more than 20 million during the Second World War alone. The extent of these loses can be judged from the following: between 1897 and 1913 the population of Russia increased at the rate of 1.55% per annum or 34.6 million; if this had continued the population would have been at least 182.8 million by the end of 1922. As it was, the population was 136.1 million by 1922 and the hypothetical 182.8 million was not reached until 1952. More than 4/5 of today's population have been born since the October Revolution. Only 43 million were born before the revolution and only 7.5 were born in the last century. The economic base has grown much more rapidly than the population. For the period 1940-1972 the population increased 1.27 times, national income 9.51 times, fixed assets, 8.76 times, industrial production, 13.65 times, agricultural output, 2.14 times, and capital investment 14.52 times. The birthrate has been falling since World War 1 but total population growth has increased steadily. Birthrates have declined from 45.5/1000 in 1913 to 17.8/1000 in 1972 and a slight upturn is seen. It is expected that the birthrate will continue to increase slightly, then stabilize. Much of the population increase has come from significantly reduced mortality rates. 1st and 2nd children now account for 71% of all births. Family allowances, child care, free health care, and other social benefits encourage births while high employment levels for women, a shortage of men in the marriageable age ranges, and late marriages tend to depress the birthrate

  8. Components and public health impact of population growth in the Arab world.

    Directory of Open Access Journals (Sweden)

    Asharaf Abdul Salam

    Full Text Available The Arab world, which consists of the 22 member states of the Arab League, is undergoing a rapid transition in demographics, including fertility, mortality, and migration. Comprising a distinctive geographic region spread across West Asia and North East Africa and unified by the Arabic language, these states share common values and characteristics despite having diverse economic and political conditions. The demographic lag (high fertility and low mortality that characterizes the Arab world is unique, but the present trend of declining fertility, combined with the relatively low mortality, brings about significant changes in its population size. This research aimed to: (i assess the population growth in the Arab world over 3 time periods, (ii explore its components, and (iii understand its public health impact. Data from the International Data Base (IDB of the U.S. Census Bureau for 3 time periods (1992, 2002, and 2012 in 21 countries of the Arab world were analyzed by dividing them into four geographic sectors, namely, the Gulf Cooperation Council (GCC, West Asia, Maghreb, and the Nile Valley African Horn. The population of the Arab world has grown considerably due to both natural growth and migration. The immigration is pronounced, especially into resource-intensive GCC nations, not only from East Asian and Central African countries but also from resource-thrifty (limited-resource Arab nations. The migrations within, as well as outside, the Arab world reveal an interesting demographic phenomenon that requires further research: migration flows and trends. However, the transformations in public health statistics related to mortality-the impact of demographic changes-depict a new era in the Arab world.

  9. Growth and Reproduction of Glyphosate-Resistant and Susceptible Populations of Kochia scoparia

    Science.gov (United States)

    Kumar, Vipan; Jha, Prashant

    2015-01-01

    Evolution of glyphosate-resistant kochia is a threat to no-till wheat-fallow and glyphosate-resistant (GR) cropping systems of the US Great Plains. The EPSPS (5-enol-pyruvylshikimate-3-phosphate synthase) gene amplification confers glyphosate resistance in the tested Kochia scoparia (L.) Schrad populations from Montana. Experiments were conducted in spring to fall 2014 (run 1) and summer 2014 to spring 2015 (run 2) to investigate the growth and reproductive traits of the GR vs. glyphosate-susceptible (SUS) populations of K. scoparia and to determine the relationship of EPSPS gene amplification with the level of glyphosate resistance. GR K. scoparia inbred lines (CHES01 and JOP01) exhibited 2 to 14 relative copies of the EPSPS gene compared with the SUS inbred line with only one copy. In the absence of glyphosate, no differences in growth and reproductive parameters were evident between the tested GR and SUS inbred lines, across an intraspecific competition gradient (1 to 170 plants m-2). GR K. scoparia plants with 2 to 4 copies of the EPSPS gene survived the field-use rate (870 g ha-1) of glyphosate, but failed to survive the 4,350 g ha-1 rate of glyphosate (five-times the field-use rate). In contrast, GR plants with 5 to 14 EPSPS gene copies survived the 4,350 g ha-1 of glyphosate. The results from this research indicate that GR K. scoparia with 5 or more EPSPS gene copies will most likely persist in field populations, irrespective of glyphosate selection pressure. PMID:26580558

  10. Components and public health impact of population growth in the Arab world.

    Science.gov (United States)

    Abdul Salam, Asharaf; Elsegaey, Ibrahim; Khraif, Rshood; AlMutairi, Abdullah; Aldosari, Ali

    2015-01-01

    The Arab world, which consists of the 22 member states of the Arab League, is undergoing a rapid transition in demographics, including fertility, mortality, and migration. Comprising a distinctive geographic region spread across West Asia and North East Africa and unified by the Arabic language, these states share common values and characteristics despite having diverse economic and political conditions. The demographic lag (high fertility and low mortality) that characterizes the Arab world is unique, but the present trend of declining fertility, combined with the relatively low mortality, brings about significant changes in its population size. This research aimed to: (i) assess the population growth in the Arab world over 3 time periods, (ii) explore its components, and (iii) understand its public health impact. Data from the International Data Base (IDB) of the U.S. Census Bureau for 3 time periods (1992, 2002, and 2012) in 21 countries of the Arab world were analyzed by dividing them into four geographic sectors, namely, the Gulf Cooperation Council (GCC), West Asia, Maghreb, and the Nile Valley African Horn. The population of the Arab world has grown considerably due to both natural growth and migration. The immigration is pronounced, especially into resource-intensive GCC nations, not only from East Asian and Central African countries but also from resource-thrifty (limited-resource) Arab nations. The migrations within, as well as outside, the Arab world reveal an interesting demographic phenomenon that requires further research: migration flows and trends. However, the transformations in public health statistics related to mortality-the impact of demographic changes-depict a new era in the Arab world.

  11. Cell Differentiation in a Bacillus thuringiensis Population during Planktonic Growth, Biofilm Formation, and Host Infection.

    Science.gov (United States)

    Verplaetse, Emilie; Slamti, Leyla; Gohar, Michel; Lereclus, Didier

    2015-04-28

    Bacillus thuringiensis (Bt) is armed to complete a full cycle in its insect host. During infection, virulence factors are expressed under the control of the quorum sensor PlcR to kill the host. After the host's death, the quorum sensor NprR controls a necrotrophic lifestyle, allowing the vegetative cells to use the insect cadaver as a bioincubator and to survive. Only a part of the Bt population sporulates in the insect cadaver, and the precise composition of the whole population and its evolution over time are unknown. Using fluorescent reporters to record gene expression at the single-cell level, we have determined the differentiation course of a Bt population and explored the lineage existing among virulent, necrotrophic, and sporulating cells. The dynamics of cell differentiation were monitored during growth in homogenized medium, biofilm formation, and colonization of insect larvae. We demonstrated that in the insect host and in planktonic culture in rich medium, the virulence, necrotrophism, and sporulation regulators are successively activated in the same cell. In contrast, in biofilms, activation of PlcR is dispensable for NprR activation and we observed a greater heterogeneity than under the other two growth conditions. We also showed that sporulating cells arise almost exclusively from necrotrophic cells. In biofilm and in the insect cadaver, we identified an as-yet-uncharacterized category of cells that do not express any of the reporters used. Overall, we showed that PlcR, NprR, and Spo0A act as interconnected integrators to allow finely tuned adaptation of the pathogen to its environment. Bt is an entomopathogen found ubiquitously in the environment and is a widely used biopesticide. Studies performed at the population level suggest that the infection process of Bt includes three successive steps (virulence, necrotrophism, and sporulation) controlled by different regulators. This study aimed to determine how these phenotypes are activated at the

  12. Assessment of the growth of epidural injections in the medicare population from 2000 to 2011.

    Science.gov (United States)

    Manchikanti, Laxmaiah; Pampati, Vidyasagar; Falco, Frank J E; Hirsch, Joshua A

    2013-01-01

    Among the many diagnostic and therapeutic interventions available for the management of chronic pain, epidural steroid injections are one of the most commonly used modalities. The explosive growth of this technique is relevant in light of the high cost of health care in the United States and abroad, the previous literature assessing the effectiveness of epidural injections has been sparse with highly variable outcomes based on technique, outcome measures, patient selection, and methodology. However, the recent assessment of fluoroscopically directed epidural injections has shown improved evidence with proper inclusion criteria, methodology, and outcome measures. The exponential growth of epidural injections is illustrated in multiple reports. The present report is an update of the analysis of the growth of epidural injections in the Medicare population from 2000 to 2011 in the United States. Analysis of utilization patterns of epidural procedures in the Medicare population in the United States from 2000 to 2011. The primary purpose of this assessment was to evaluate the use of all types of epidural injections (i.e., caudal, interlaminar, and transforaminal in the lumbar, cervical, and thoracic regions) with an assessment of specialty and regional characteristics. This assessment was performed utilizing the Centers for Medicare and Medicaid Services (CMS) Physician/Supplier Procedure Summary (PSPS) Master data from 2000 to 2011. Epidural injections in Medicare beneficiaries increased significantly from 2000 to 2011. Overall, epidural injections increased 130% per 100,000 Medicare beneficiaries with an annual increase of 7.5%. The increases per 100,000 Medicare recipients were 123% for cervical/thoracic interlaminar epidural injections; 25% for lumbar/sacral interlaminar, or caudal epidural injections; 142% for cervical/thoracic transforaminal epidural injections; and 665% for lumbar/sacral transforaminal epidural injections. The use of epidurals increased 224% in

  13. Rate and time trend of perinatal, infant, maternal mortality, natality and natural population growth in kosovo.

    Science.gov (United States)

    Azemi, Mehmedali; Gashi, Sanije; Berisha, Majlinda; Kolgeci, Selim; Ismaili-Jaha, Vlora

    2012-01-01

    THE AIM OF WORK HAS BEEN THE PRESENTATION OF THE RATE AND TIME TRENDS OF SOME INDICATORS OF THE HEATH CONDITION OF MOTHERS AND CHILDREN IN KOSOVO: fetal mortality, early neonatal mortality, perinatal mortality, infant mortality, natality, natural growth of population etc. The treated patients were the newborn and infants in the post neonatal period, women during their pregnancy and those 42 days before and after the delivery. THE DATA WERE TAKEN FROM: register of the patients treated in the Pediatric Clinic of Prishtina, World Health Organization, Mother and Child Health Care, Reproductive Health Care, Ministry of Health of the Republic of Kosovo, Statistical Department of Kosovo, the National Institute of Public Health and several academic texts in the field of pediatrics. Some indicators were analyzed in a period between year 1945-2010 and 1950-2010, whereas some others were analyzed in a time period between year 2000 and 2011. The perinatal mortality rate in 2000 was 29.1‰, whereas in 2011 it was 18.7‰. The fetal mortality rate was 14.5‰ during the year 2000, whereas in 2011 it was 11.0‰, in 2000 the early neonatal mortality was 14.8‰, in 2011 it was 7.5‰. The infant mortality in Kosovo was 164‰ in 1950, whereas in 2010 it was 20.5‰. The most frequent causes of infant mortality have been: lower respiratory tract infections, acute infective diarrhea, perinatal causes, congenital malformations and unclassified conditions. Maternal death rate varied during this time period. Maternal death in 2000 was 23 whereas in 2010 only two cases were reported. Regarding the natality, in 1950 it reached 46.1 ‰, whereas in 2010 it reached 14‰, natural growth of population rate in Kosovo was 29.1‰ in 1950, whereas in 2011 it was 11.0‰. Perinatal mortality rate in Kosovo is still high in comparison with other European countries (Turkey and Kyrgyzstan have the highest perinatal mortality rate), even though it is in a continuous decrease. Infant mortality

  14. Rate and Time Trend of Perinatal, Infant, Maternal Mortality, Natality and Natural Population Growth in Kosovo

    Science.gov (United States)

    Azemi, Mehmedali; Gashi, Sanije; Berisha, Majlinda; Kolgeci, Selim; Ismaili-Jaha, Vlora

    2012-01-01

    Aim: The aim of work has been the presentation of the rate and time trends of some indicators of the heath condition of mothers and children in Kosovo: fetal mortality, early neonatal mortality, perinatal mortality, infant mortality, natality, natural growth of population etc. The treated patients were the newborn and infants in the post neonatal period, women during their pregnancy and those 42 days before and after the delivery. Methods: The data were taken from: register of the patients treated in the Pediatric Clinic of Prishtina, World Health Organization, Mother and Child Health Care, Reproductive Health Care, Ministry of Health of the Republic of Kosovo, Statistical Department of Kosovo, the National Institute of Public Health and several academic texts in the field of pediatrics. Some indicators were analyzed in a period between year 1945-2010 and 1950-2010, whereas some others were analyzed in a time period between year 2000 and 2011. Results: The perinatal mortality rate in 2000 was 29.1‰, whereas in 2011 it was 18.7‰. The fetal mortality rate was 14.5‰ during the year 2000, whereas in 2011 it was 11.0‰, in 2000 the early neonatal mortality was 14.8‰, in 2011 it was 7.5‰. The infant mortality in Kosovo was 164‰ in 1950, whereas in 2010 it was 20.5‰. The most frequent causes of infant mortality have been: lower respiratory tract infections, acute infective diarrhea, perinatal causes, congenital malformations and unclassified conditions. Maternal death rate varied during this time period. Maternal death in 2000 was 23 whereas in 2010 only two cases were reported. Regarding the natality, in 1950 it reached 46.1 ‰, whereas in 2010 it reached 14‰, natural growth of population rate in Kosovo was 29.1‰ in 1950, whereas in 2011 it was 11.0‰. Conclusion: Perinatal mortality rate in Kosovo is still high in comparison with other European countries (Turkey and Kyrgyzstan have the highest perinatal mortality rate), even though it is in a

  15. World population and energy growth: Impact on the Caribbean and the roles of energy efficiency improvements and renewable energies

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, J.

    1997-06-01

    This paper briefly describes population and energy use trends and their consequences, particularly to the Caribbean region. Historical trends for transitional countries show a decrease in population growth rate as annual per capita commercial energy use increases. If trends continue, an increase in per capita energy will be important to stabilizing populations of transitional countries. Energy efficiency improvements, the role of fossil energy, and the use of alternative energy sources in Caribbean nations are briefly discussed. 6 refs., 3 figs.

  16. Morbidity, rickets and long-bone growth in post-medieval Britain--a cross-population analysis.

    Science.gov (United States)

    Pinhasi, R; Shaw, P; White, B; Ogden, A R

    2006-01-01

    Vitamin D deficiency rickets is associated with skeletal deformities including swollen rib junctions, bowing of the legs, and the flaring and fraying of the wrist and long-bone metaphyses. There is, however, scarce information on the direct effect of rickets on skeletal growth in either present or past populations. The study investigated the effect of vitamin D deficiency rickets on long-bone growth in two post-medieval skeletal populations from East London (Broadgate and Christ Church Spitalfields). Subsequently, inter-population growth variations in relation to non-specific environmental stress (dental enamel defects), industrialization, urbanization and socio-economic status during infancy (birth to 3 years) and early childhood (3-7 years) were examined. Data on long-bone diaphyseal length dimensions and stress indicators of 234 subadults from Anglo-Saxon, late medieval and post-medieval archaeological skeletal samples were analysed using both linear and non-linear growth models. Rickets had no effect on the growth curves for any of the long bones studied. However, pronounced variations in growth between the four populations were noted, mainly during infancy. The diaphyseal length of long bones of Broadgate were significantly smaller-per-age than those of Spitalfields and the other samples up to the age of 4 years, and were associated with a high prevalence of enamel defects during early infancy. Socio-economic status, rather than urbanization, industrialization or rickets, was the central factor behind the observed differences in growth among the post-medieval populations. The observed inter-population growth variations were only significant during infancy.

  17. Estimating the effects of 17α-ethinylestradiol on stochastic population growth rate of fathead minnows: a population synthesis of empirically derived vital rates

    Science.gov (United States)

    Schwindt, Adam R.; Winkelman, Dana L.

    2016-01-01

    Urban freshwater streams in arid climates are wastewater effluent dominated ecosystems particularly impacted by bioactive chemicals including steroid estrogens that disrupt vertebrate reproduction. However, more understanding of the population and ecological consequences of exposure to wastewater effluent is needed. We used empirically derived vital rate estimates from a mesocosm study to develop a stochastic stage-structured population model and evaluated the effect of 17α-ethinylestradiol (EE2), the estrogen in human contraceptive pills, on fathead minnow Pimephales promelas stochastic population growth rate. Tested EE2 concentrations ranged from 3.2 to 10.9 ng L−1 and produced stochastic population growth rates (λ S ) below 1 at the lowest concentration, indicating potential for population decline. Declines in λ S compared to controls were evident in treatments that were lethal to adult males despite statistically insignificant effects on egg production and juvenile recruitment. In fact, results indicated that λ S was most sensitive to the survival of juveniles and female egg production. More broadly, our results document that population model results may differ even when empirically derived estimates of vital rates are similar among experimental treatments, and demonstrate how population models integrate and project the effects of stressors throughout the life cycle. Thus, stochastic population models can more effectively evaluate the ecological consequences of experimentally derived vital rates.

  18. Why Does Population Aging Matter So Much for Asia? Population Aging, Economic Security and Economic Growth in Asia

    OpenAIRE

    Sang-Hyop LEE; Andrew MASON; Donghyun PARK

    2011-01-01

    Asia as a whole is experiencing a rapid demographic transition toward older population structures. Within this broader region-wide trend, there is considerable heterogeneity, with different countries at different stages of the demographic transition. In this paper, we document Asia’s population aging, describe the region’s old-age support systems, and draw out the regional socioeconomic implications of population aging and old-age support systems. Population aging gives rise to two fundamenta...

  19. The protective function of personal growth initiative among a genocide-affected population in Rwanda.

    Science.gov (United States)

    Blackie, Laura E R; Jayawickreme, Eranda; Forgeard, Marie J C; Jayawickreme, Nuwan

    2015-07-01

    The aim of the current study was to investigate the extent to which individual differences in personal growth initiative (PGI) were associated with lower reports of functional impairment of daily activities among a genocide-affected population in Rwanda. PGI measures an individual's motivation to develop as a person and the extent to which he or she is active in setting goals that work toward achieving self-improvement. We found that PGI was negatively associated with functional impairment when controlling for depression, posttraumatic stress disorder, and other demographic factors. Our results suggest that PGI may constitute an important mindset for facilitating adaptive functioning in the aftermath of adversity and in the midst of psychological distress, and as such they might have practical applications for the development of intervention programs. (c) 2015 APA, all rights reserved).

  20. The 'Natural Laboratory', a tool for deciphering growth, lifetime and population dynamics in larger benthic foraminifera

    Science.gov (United States)

    Hohenegger, Johann

    2015-04-01

    The shells of symbiont-bearing larger benthic Foraminifera (LBF) represent the response to physiological requirements in dependence of environmental conditions. All compartments of the shell such as chambers and chamberlets accommodate the growth of the cell protoplasm and are adaptations for housing photosymbiotic algae. Investigations on the biology of LBF were predominantly based on laboratory studies. The lifetime of LBF under natural conditions is still unclear. LBF, which can build >100 chambers during their lifetime, are thought to live at least one year under natural conditions. This is supported by studies on population dynamics of eulittoral foraminifera. In species characterized by a time-restricted single reproduction period the mean size of specimens increases from small to large during lifetime simultaneously reducing individual number. This becomes more complex when two or more reproduction times are present within a one-year cycle leading to a mixture of abundant small individuals with few large specimens during the year, while keeping mean size more or less constant. This mixture is typical for most sublittoral megalospheric (gamonts or schizonts) LBF. Nothing is known on the lifetime of agamonts, the diploid asexually reproducing generation. In all hyaline LBF it is thought to be significantly longer than 1 year based on the large size and considering the mean chamber building rate of the gamont/schizonts. Observations on LBF under natural conditions have not been performed yet in the deeper sublittoral. This reflects the difficulties due to intense hydrodynamics that hinder deploying technical equipment for studies in the natural environment. Therefore, studying growth, lifetime and reproduction of sublittoral LBF under natural conditions can be performed using the so-called 'natural laboratory' in comparison with laboratory investigations. The best sampling method in the upper sublittoral from 5 to 70 m depth is by SCUBA diving. Irregular

  1. Richards growth model and viability indicators for populations subject to interventions

    Directory of Open Access Journals (Sweden)

    Selene Loibel

    2010-12-01

    Full Text Available In this work we study the problem of modeling identification of a population employing a discrete dynamic model based on the Richards growth model. The population is subjected to interventions due to consumption, such as hunting or farming animals. The model identification allows us to estimate the probability or the average time for a population number to reach a certain level. The parameter inference for these models are obtained with the use of the likelihood profile technique as developed in this paper. The identification method here developed can be applied to evaluate the productivity of animal husbandry or to evaluate the risk of extinction of autochthon populations. It is applied to data of the Brazilian beef cattle herd population, and the the population number to reach a certain goal level is investigated.Neste trabalho estudamos o problema de identificação do modelo de uma população utilizando um modelo dinâmico discreto baseado no modelo de crescimento de Richards. A população é submetida a intervenções devido ao consumo, como no caso de caça ou na criação de animais. A identificação do modelo permite-nos estimar a probabilidade ou o tempo médio de ocorrência para que se atinja um certo número populacional. A inferência paramétrica dos modelos é obtida através da técnica de perfil de máxima verossimilhança como desenvolvida neste trabalho. O método de identificação desenvolvido pode ser aplicado para avaliar a produtividade de criação animal ou o risco de extinção de uma população autóctone. Ele foi aplicado aos dados da população global de gado de corte bovino brasileiro, e é utilizado na investigação de a população atingir um certo número desejado de cabeças.

  2. Reproduction, abundance, and population growth for a fisher (Pekania pennanti) population in the Sierra National Forest, California

    Science.gov (United States)

    Rick A. Sweitzer; Viorel D. Popescu; Reginald H. Barrett; Kathryn L. Purcell; Craig M. Thompson

    2015-01-01

    In the west coast region of the United States, fishers (Pekania pennanti) exist in 2 remnant populations—1 in northern California and 1 in the southern Sierra Nevada, California—and 3 reintroduced populations (western Washington, southern Oregon, and northeastern California). The West Coast Distinct Population Segment of fishers encompassing all of...

  3. Nutrient foraging strategies are associated with productivity and population growth in forest shrubs.

    Science.gov (United States)

    Caplan, Joshua S; Stone, Bram W G; Faillace, Cara A; Lafond, Jonathan J; Baumgarten, Joni M; Mozdzer, Thomas J; Dighton, John; Meiners, Scott J; Grabosky, Jason C; Ehrenfeld, Joan G

    2017-04-01

    Temperate deciduous forest understoreys are experiencing widespread changes in community composition, concurrent with increases in rates of nitrogen supply. These shifts in plant abundance may be driven by interspecific differences in nutrient foraging (i.e. conservative vs. acquisitive strategies) and, thus, adaptation to contemporary nutrient loading conditions. This study sought to determine if interspecific differences in nutrient foraging could help explain patterns of shrub success and decline in eastern North American forests. Using plants grown in a common garden, fine root traits associated with nutrient foraging were measured for six shrub species. Traits included the mean and skewness of the root diameter distribution, specific root length (SRL), C:N ratio, root tissue density, arbuscular mycorrhizal colonization and foraging precision. Above- and below-ground productivity were also determined for the same plants, and population growth rates were estimated using data from a long-term study of community dynamics. Root traits were compared among species and associations among root traits, measures of productivity and rates of population growth were evaluated. Species fell into groups having thick or thin root forms, which correspond to conservative vs. acquisitive nutrient foraging strategies. Interspecific variation in root morphology and tissue construction correlated with measures of productivity and rates of cover expansion. Of the four species with acquisitive traits, three were introduced species that have become invasive in recent decades, and the fourth was a weedy native. In contrast, the two species with conservative traits were historically dominant shrubs that have declined in abundance in eastern North American forests. In forest understoreys of eastern North America, elevated nutrient availability may impose a filter on species success in addition to above-ground processes such as herbivory and overstorey canopy conditions. Shrubs that have

  4. Intrauterine growth standards: a cross-sectional study in a population of Nigerian newborns

    Directory of Open Access Journals (Sweden)

    Olugbenga A. Mokuolu

    2012-09-01

    Full Text Available The aim of the study was to define an intrauterine growth curve for a population of Nigerian newborn babies. A cross-sectional observational study design was adopted. Weight, length and head circumference were all measured in consecutive singleton deliveries at the University of Ilorin Teaching Hospital over a 3-year period. Gestational age (GA of the babies was estimated from the last menstrual period or first trimester ultrasound. The estimates obtained were clinically validated using the Ballard score. Mean birth weights and percentiles of the weight, length and head circumferences for the respective GA were estimated using the SPSS 15 software package. A total of 5273 babies were recruited for the study with GA ranging from 25-44 weeks. Comparison of the mean birth weights of the various GA with the data from Denver, Colorado, showed that Nigerian babes tended to weigh less at the early GA, although these differences were not statistically significant. Between 26-36 weeks, the average weights of both sexes were similar; however, beyond this time point there was a consistent increase in the average weight of the males over the female babies. Growth curves for Nigerian newborn babies were generated and showed that the mean birth weight of Nigerian preterm babies was lighter than that of babies in Colorado. The impact of these differences on the classification of newborns will require further evaluation.

  5. Growth and demographic patterns of marriages of foreign population in Spain

    Directory of Open Access Journals (Sweden)

    Clara Cortina

    2014-11-01

    Full Text Available The dramatic growth of international immigration in Spain during the last decade has considerably increased the number of marriages with at least one foreign national. Between 1989 and 2004, the proportion of these marriages increased from 4% to12%, totalling 25.618 unions in 2004. However, marriage patterns of foreign nationals have attracted little attention among researcher spartly because of the small number of cases that were available until recently. Within this context, this paper examines the growth and demographic patterns of marriages of foreign populationin Spain, compared to those of only Spanish nationals, taking into account the age at marriage, type of union (religious or civil,first and later order of marriages, and degree of endogamy. We use microdata from the Spanish vital statistics on marriages (Movimiento Natural de la Población between 1989 and 2004. Results show that marriages of foreign population in Spain, particularly those that involve one Spanish partner, present some distinct characteristics, in particular associated with gender, in contrast to those marriages that only involve Spanish nationals.

  6. Compound haplotypes at Xp11.23 and human population growth in Eurasia.

    Science.gov (United States)

    Alonso, S; Armour, J A L

    2004-09-01

    To investigate patterns of diversity and the evolutionary history of Eurasians, we have sequenced a 2.8 kb region at Xp11.23 in a sample of African and Eurasian chromosomes. This region is in a long intron of CLCN5 and is immediately flanked by a highly variable minisatellite, DXS255, and a human-specific Ta0 LINE. Compared to Africans, Eurasians showed a marked reduction in sequence diversity. The main Euro-Asiatic haplotype seems to be the ancestral haplotype for the whole sample. Coalescent simulations, including recombination and exponential growth, indicate a median length of strong linkage disequilibrium, up to approximately 9 kb for this area. The Ka/Ks ratio between the coding sequence of human CLCN5 and its mouse orthologue is much less than 1. This implies that the region sequenced is unlikely to be under the strong influence of positive selective processes on CLCN5, mutations in which have been associated with disorders such as Dent's disease. In contrast, a scenario based on a population bottleneck and exponential growth seems a more likely explanation for the reduced diversity observed in Eurasians. Coalescent analysis and linked minisatellite diversity (which reaches a gene diversity value greater than 98% in Eurasians) suggest an estimated age of origin of the Euro-Asiatic diversity compatible with a recent out-of-Africa model for colonization of Eurasia by modern Homo sapiens.

  7. Involvement of Fibroblast Growth Factor Receptor Genes in Benign Prostate Hyperplasia in a Korean Population

    Directory of Open Access Journals (Sweden)

    Hae Jeong Park

    2013-01-01

    Full Text Available Fibroblast growth factors (FGFs and their receptors (FGFRs have been implicated in prostate growth and are overexpressed in benign prostatic hyperplasia (BPH. In this study, we investigated whether single nucleotide polymorphisms (SNPs of the FGFR genes (FGFR1 and FGFR2 were associated with BPH and its clinical phenotypes in a population of Korean men. We genotyped four SNPs in the exons of FGFR1 and FGFR2 (rs13317 in FGFR1; rs755793, rs1047100, and rs3135831 in FGFR2 using direct sequencing in 218 BPH patients and 213 control subjects. No SNPs of FGFR1 or FGFR2 genes were associated with BPH. However, analysis according to clinical phenotypes showed that rs1047100 of FGFR2 was associated with prostate volume in BPH in the dominant model (GA/AA versus GG, P = 0.010. In addition, a significant association was observed between rs13317 of FGFR1 and international prostate symptom score (IPSS in the additive (TC versus CC versus TT, P = 0.0022 and dominant models (TC/CC versus TT, P = 0.005. Allele frequency analysis also showed significant association between rs13317 and IPSS (P = 0.005. These results suggested that FGFR genes could be related to progression of BPH.

  8. Growth comparison in children with and without food allergies in 2 different demographic populations.

    Science.gov (United States)

    Mehta, Harshna; Ramesh, Manish; Feuille, Elizabeth; Groetch, Marion; Wang, Julie

    2014-10-01

    To examine the effects of food avoidance on the growth of children with food allergies. A retrospective chart review was performed for children with and without food allergies followed at 2 New York City general pediatric practices. Charts were selected based on codes from the International Classification of Diseases, 9th Revision, for well child visit, food allergy, anaphylaxis, and/or epinephrine autoinjector prescriptions. Heights and weights were obtained to calculate body mass index, height, and weight z-scores. Of the 9938 children seen, 439 (4.4%) were avoiding one or more foods. Of those with commercial insurance, children with food allergies were significantly shorter (mean height z-score = 0.06; P = .01) and weighed less (mean weight z-score -0.1; P = .006) than children without food allergies (mean height z-score = 0.42; mean weight z-score = 0.07). In contrast, children with food allergies and state insurance were not smaller in height or weight compared with children without food allergies. Among white subjects, there was a significant effect of food allergies on height and weight (ANOVA for height P = .012, for weight P = .0036) that was not observed for Hispanic/Latino, black, or Asian subjects. Children with allergies to milk weighed significantly less than children without milk allergies (P = .0006). Children with food allergies and commercial insurance have significant impairment in growth compared with those without food allergies. Additionally, children avoiding all forms of milk are shorter and weigh less than matched counterparts. Therefore, height and weight measurements should be assessed routinely in children with food allergies because there is risk for growth impairment in this population. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Feeding the world's increasing population while limiting climate change impacts; decoupling agriculture' s N2O and CH4 emissions from population growth

    NARCIS (Netherlands)

    Beek, C.L.; Meerburg, B.G.; Schils, R.L.M.; Verhagen, J.; Kuikman, P.J.

    2010-01-01

    The global demand for agricultural products, including food, is rapidly increasing due to population growth and shifts in consumption patterns. The required increase in agricultural production is predominantly to be achieved in countries with relatively low agricultural production levels at present.

  10. GADD45β Determines Chemoresistance and Invasive Growth of Side Population Cells of Human Embryonic Carcinoma

    Directory of Open Access Journals (Sweden)

    Toshihiko Inowa

    2010-01-01

    Full Text Available Side population (SP cells are an enriched population of stem, and the existence of SP cells has been reported in human cancer cell lines. In this study, we performed an SP analysis using 11 human cancer cell lines and confirmed the presence of SP cells in an embryonic carcinoma cell line, NEC8. NEC8 SP cells showed characteristics of cancer stem cells, such as high growth rate, chemoresistance and high invasiveness. To further characterize the NEC8 SP cells, we used DNA microarrays. Among 38,500 genes, we identified 12 genes that were over-expressed in SP cells and 1 gene that was over-expressed in non-SP cells. Among these 13 genes, we focused on GADD45b. GADD45b was over-expressed in non-SP cells, but the inhibition of GADD45b had no effect on non-SP cells. Paradoxically, the inhibition of GADD45b significantly reduced the viability of NEC8 SP cells. The inhibition of ABCG2, which determines the SP phenotype, had no effect on the invasiveness of NEC8 SP cells, but the inhibition of GADD45b significantly reduced invasiveness. These results suggest that GADD45b, but not ABCG2, might determine the cancer stem cell-like phenotype, such as chemoresistance and the high invasiveness of NEC8 SP cells, and might be a good therapeutic target.

  11. Effect of Portulaca oleracea extracts on growth performance and microbial populations in ceca of broilers.

    Science.gov (United States)

    Zhao, X H; He, X; Yang, X F; Zhong, X H

    2013-05-01

    The aim of this study was to investigate the effects of Portulaca oleracea extracts on growth performance and microbial populations in the ceca of broilers. A total of 120 one-day-old broilers were randomly divided into 3 groups. Portulaca oleracea extracts were added to diets at 0.2 and 0.4% (wt/wt; POL-0.2, POL-0.4), respectively. The control (CON) group was administered with no P. oleracea extract supplementation. Body weight gain and feed conversion ratio were recorded every 2 wk. On d 28 and 42, the cecal contents were collected and assayed for Escherichia coli, Lactobacillus, and Bifidobacterium populations. Additionally, the pH of the ileum and cecum was measured. The results showed that both on d 28 and 42 BW gain of P. oleracea extract supplementation groups was significantly higher, whereas the feed conversion ratio was lower (P < 0.05) compared with CON. On d 28 and 42, significantly (P < 0.05) fewer E. coli were recovered from ceca of broilers provided with the POL-0.2 diet than from broilers provided with the control diet. The quantities of Lactobacillus and Bifidobacterium of POL-0.2 were significantly (P < 0.05) higher than CON. Results showed P. oleracea extracts have no distinct influence on intestinal pH. These data suggest that P. oleracea extract supplementation significantly altered the cecal bacterial community without affecting the intestinal pH.

  12. Recent and rapid population growth and range expansion of the Lyme disease tick vector, Ixodes scapularis, in North America.

    Science.gov (United States)

    Khatchikian, Camilo E; Prusinski, Melissa A; Stone, Melissa; Backenson, Peter Bryon; Wang, Ing-Nang; Foley, Erica; Seifert, Stephanie N; Levy, Michael Z; Brisson, Dustin

    2015-07-01

    Migration is a primary force of biological evolution that alters allele frequencies and introduces novel genetic variants into populations. Recent migration has been proposed as the cause of the emergence of many infectious diseases, including those carried by blacklegged ticks in North America. Populations of blacklegged ticks have established and flourished in areas of North America previously thought to be devoid of this species. The recent discovery of these populations of blacklegged ticks may have resulted from either in situ growth of long-established populations that were maintained at very low densities or by migration and colonization from established populations. These alternative evolutionary hypotheses were investigated using Bayesian phylogeographic approaches to infer the origin and migratory history of recently detected blacklegged tick populations in the Northeastern United States. The data and results indicate that newly detected tick populations are not the product of in situ population growth from a previously established population but from recent colonization resulting in a geographic range expansion. This expansion in the geographic range proceeded primarily through progressive and local migration events from southern populations to proximate northern locations although long-distance migration events were also detected. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  13. Vascular endothelial growth factor (VEGFA gene variation in polycystic ovary syndrome in a Tunisian women population

    Directory of Open Access Journals (Sweden)

    Assila Ben Salem

    2016-10-01

    Full Text Available Abstract Background Polycystic ovary syndrome (PCOS is characterized by the growth of a number of small cysts on the ovaries which leads to sex hormonal imbalance. Women who are affected by this syndrome suffer from irregular menstrual cycles, decline in their fertility, excessive hair growth, obesity, acne and most importantly cardiac function problems. The vascular endothelial growth factor (VEGF plays a pivotal role in tissue vascularization in general and in the pathogenesis of many diseases. The PCOS was found to be associated with high expression levels of VEGF. In women who undergo assisted reproductive procedures (ART, VEGF was found to be a key mediator of other factors to control ovary angiogenesis. Here, we set out to examine the association of VEGFA gene polymorphism with PCOS and its components in a population of Tunisia women to enhance our understanding of the genetic background leading angiogenesis and vascularization abnormalities in PCOS. Methods The association of VEGFA gene with PCOS and its components was examined in a cohort of 268 women from Tunisia involving 118 PCOS patients and 150 controls. VEGFA gene variations were assessed through the analysis of the following SNPs rs699947 (A/C, rs833061 (C/T, rs1570360 (G/A, rs833068 (G/A, rs3025020 (C/T, and rs3025039 (C/T. The linkage disequilibrium between SNPs was assessed using HAPLOVIEW software while combination of SNPs into haplotypes in the population and the reconstruction of the cladogram were carried-out by PHASE and ARLEQUIN programs, respectively. Genetic association and genotype-phenotype correlations were calculated by logistic regression and non-parametric tests (Kruskall-Wallis and Mann–Whitney tests, respectively, using StatView program. Results We observed 10 haplotypes in our studied cohort whereH1 (ACGG, H2 (ACAG, H7 (CTGG and H8 (CTGA were the most frequent. We observed the association of the genotype CT of the SNP rs30225039 with PCOS phenotype (P = 0

  14. Effects of wind energy production on growth, demography, and survivorship of a Desert Tortoise (Gopherus agassizii) population in Southern California with comparisons to natural populations

    Science.gov (United States)

    Lovich, J.E.; Ennen, J.R.; Madrak, S.; Meyer, K.; Loughran, C.; Bjurlin, C.; Arundel, T.; Turner, W.; Jones, C.; Groenendaal, G.M.

    2011-01-01

    We studied a Desert Tortoise (Gopherus agassizii) population at a large wind energy generation facility near Palm Springs, California over six field seasons from 1997 to 2010. We compared growth and demographic parameters to populations living in less disturbed areas; as well as populations of the closely-related and newly-described G. morafkai elsewhere in the Sonoran Desert of Arizona. We marked 69 individuals of all size classes and estimated a population size of 96 tortoises, or about 15.4/km2. Growth rates for males were lower than reported elsewhere, although maximum body size was larger. The smallest female with shelled eggs was 221 mm and males mature at over 200 mm. Mean male size was greater than that of females. The adult sex ratio was not significantly different from unity. Size frequency histograms were similar over time and when compared to most, but not all, G. morafkai populations in the Sonoran Desert. For a cohort of adult females, we estimated mortality at 8.4% annually due, in part, to site operations. This value was low in comparison to many other populations during the same time period. Other than possible differences in growth rate of males and the high survivorship of females, there appear to be few differences between this population and those in more natural areas. The high productivity of food plants at the site and its limited public access may contribute to the overall stability of the population. However, the effects of utility-scale renewable energy development on tortoises in other, less productive, areas are unknown. Additional research (especially controlled and replicated before and after studies) is urgently needed to address this deficiency because of forecasted expansion of utility-scale renewable energy development in the future.

  15. Mating system, population growth, and management scenario for Kalanchoe pinnata in an invaded seasonally dry tropical forest.

    Science.gov (United States)

    González de León, Salvador; Herrera, Ileana; Guevara, Roger

    2016-07-01

    Ecological invasions are a major issue worldwide, where successful invasion depends on traits that facilitate dispersion, establishment, and population growth. The nonnative succulent plant Kalanchoe pinnata, reported as invasive in some countries, is widespread in remnants of seasonally dry tropical forest on a volcanic outcrop with high conservation value in east-central Mexico where we assessed its mating system and demographic growth and identified management strategies. To understand its local mating system, we conducted hand-pollination treatments, germination, and survival experiments. Based on the experimental data, we constructed a life-stage population matrix, identified the key traits for population growth, weighted the contributions of vegetative and sexual reproduction, and evaluated management scenarios. Hand-pollination treatments had slight effects on fruit and seed setting, as well as on germination. With natural pollination treatment, the successful germination of seeds from only 2/39 fruit suggests occasional effective natural cross-pollination. The ratios of the metrics for self- and cross-pollinated flowers suggest that K. pinnata is partially self-compatible. Most of the pollinated flowers developed into fruit, but the seed germination and seedling survival rates were low. Thus, vegetative propagation and juvenile survival are the main drivers of population growth. Simulations of a virtual K. pinnata population suggest that an intense and sustained weeding campaign will reduce the population within at least 10 years. Synthesis and applications. The study population is partially self-compatible, but sexual reproduction by K. pinnata is limited at the study site, and population growth is supported by vegetative propagation and juvenile survival. Demographic modeling provides key insights and realistic forecasts on invasion process and therefore is useful to design management strategies.

  16. The effect of selected plant extracts on the development of single-species dental biofilms

    International Nuclear Information System (INIS)

    Rahim, Z.H.; Shaikh, S.; Razak, A.; Ismail, W.N.H.W.

    2014-01-01

    To determine the effect of a mixture of plant extracts on the adherence and retention of bacteria in dental biofilm. Study Design: Experimental study. Place and Duration of Study:Department of Oral Biology, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia, from December 2009 to December 2011. Methodology: For determination of adhering ability, experimental pellicle was first treated with the Plant Extracts Mixture (PEM) before inoculating it with individual bacterial species ( S. mitis / S. sanguinis / S. mutans). For the determination of retention ability, the procedure was repeated with the experimental pellicle being inoculated first with the individual bacterial species and then treating it with the PEM. These two experiments were repeated with deionized distilled water (negative control) and Thymol (0.64%) (positive control). The bacterial populations in biofilms for the two experiments were expressed as Colony Forming Unit (CFU) / mL x 10/sup 4/ and the corresponding values were expressed as mean +- SD. Results: The effect of the Plant Extracts Mixture (PEM) for the two experiments was compared with that of Thymol and deionized distilled water. It was shown that there is a reduced adherence of bacteria to PEM-treated and Thymol (0.064%) treated experimental pellicle compared with the negative control (p < 0.001). It was also found that the retention of bacteria in both treated biofilms is also lower than that of negative control (p = 0.001). Conclusion: Plant Extracts Mixture (PEM) may influence the development of dental biofilm by affecting the adhering and retention capacities of the bacterial species in the dental biofilms. (author)

  17. Why Does Population Aging Matter So Much for Asia? Population Aging, Economic Growth, and Economic Security in Asia

    OpenAIRE

    Lee, Sang-Hyop; Mason, Andrew; Park, Donghyun

    2011-01-01

    Asia as a whole is experiencing a rapid demographic transition toward older populations, though different countries are at different stages of this region- wide trend. We document Asia's aging population, describe the region's old-age support systems, and highlight the regional socioeconomic implications of the transition for those support systems. Aging populations present two fundamental challenges to Asian policymakers: (1) developing socioeconomic systems that can provide economic securit...

  18. Water availability and population origin affect the expression of the tradeoff between reproduction and growth in Plantago coronopus

    DEFF Research Database (Denmark)

    Hansen, C. F.; Garcia, M. B.; Ehlers, B. K.

    2013-01-01

    temperature and precipitation. We found that water availability affected the expression of the tradeoff (both phenotypic and genetic) between reproduction and growth, being most accentuated under dry condition. However, populations responded very differently to water treatments. Plants from annual populations...... showed a similar response to drought condition with little variation among maternal families, suggesting a history of selection favouring genotypes with high allocation to reproduction when water availability is low. Plants from annual populations also expressed the highest level of plasticity...... water availability even among geographically close populations....

  19. Effects of Nitrogen Addition on Leaf Decomposition of Single-Species and Litter Mixture in Pinus tabulaeformis Forests

    Directory of Open Access Journals (Sweden)

    Jinsong Wang

    2015-12-01

    Full Text Available The litter decomposition process is closely correlated with nutrient cycling and the maintenance of soil fertility in the forest ecosystem. In particular, the intense environmental concern about atmospheric nitrogen (N deposition requires a better understanding of its influence on the litter decomposition process. This study examines the responses of single-species litter and litter mixture decomposition processes to N addition in Chinese pine (Pinus tabulaeformis Carr. ecosystems. Chinese pine litter, Mongolian oak (Quercus mongolica Fisch. ex Ledeb. litter, and a pine–oak mixture were selected from a plantation and a natural forest of Chinese pine. Four N addition treatments, i.e., control (N0: 0 kg N ha−1·year−1, low-N (N1: 5 kg N ha−1·year−1, medium-N (N2: 10 kg N ha−1·year−1, and high-N (N3: 15 kg N ha−1·year−1, were applied starting May 2010. In the plantation, N addition significantly stimulated the decomposition of the Chinese pine litter. In the natural forest, N addition had variable effects on the decomposition of single-species litter and the litter mixture. A stimulatory effect of the high-N treatment on the Chinese pine litter decomposition could be attributed to a decrease in the substrate C:N ratio. However, an opposite effect was found for the Mongolian oak litter decomposition. The stimulating effect of N addition on the Chinese pine litter may offset the suppressive effect on the Mongolian oak litter, resulting in a neutral effect on the litter mixture. These results suggest that the different responses in decomposition of single-species litter and the litter mixture to N addition are mainly attributed to litter chemical composition. Further investigations are required to characterize the effect of long-term high-level N addition on the litter decomposition as N deposition is likely to increase rapidly in the region where this study was conducted.

  20. Effect of growth conditions and substratum composition on the persistence of coliforms in mixed-population biofilms.

    OpenAIRE

    Camper, A K; Jones, W L; Hayes, J T

    1996-01-01

    Laboratory reactors operated under oligotrophic conditions were used to evaluate the importance of initial growth rate and substratum composition on the long-term persistence of coliforms in mixed-population biofilms. The inoculum growth rate had a dramatic effect on the ability of coliforms to remain on surfaces. The most slowly grown coliforms (mu = 0.05/h) survived at the highest cell concentration. Antibody staining revealed that Klebsiella pneumoniae existed primarily as discrete microco...

  1. Modeling the growth and decline of pathogen effective population size provides insight into epidemic dynamics and drivers of antimicrobial resistance.

    Science.gov (United States)

    Volz, Erik M; Didelot, Xavier

    2018-02-07

    Non-parametric population genetic modeling provides a simple and flexible approach for studying demographic history and epidemic dynamics using pathogen sequence data. Existing Bayesian approaches are premised on stochastic processes with stationary increments which may provide an unrealistic prior for epidemic histories which feature extended period of exponential growth or decline. We show that non-parametric models defined in terms of the growth rate of the effective population size can provide a more realistic prior for epidemic history. We propose a non-parametric autoregressive model on the growth rate as a prior for effective population size, which corresponds to the dynamics expected under many epidemic situations. We demonstrate the use of this model within a Bayesian phylodynamic inference framework. Our method correctly reconstructs trends of epidemic growth and decline from pathogen genealogies even when genealogical data is sparse and conventional skyline estimators erroneously predict stable population size. We also propose a regression approach for relating growth rates of pathogen effective population size and time-varying variables that may impact the replicative fitness of a pathogen. The model is applied to real data from rabies virus and Staphylococcus aureus epidemics. We find a close correspondence between the estimated growth rates of a lineage of methicillin-resistant S. aureus and population-level prescription rates of β-lactam antibiotics. The new models are implemented in an open source R package called skygrowth which is available at https://github.com/mrc-ide/skygrowth. © The Author(s) 2018. Published by Oxford University Press, on behalf of the Society of Systematic Biologists.

  2. Investigating the effect of clustering of the urban field on sustainable population growth of centrally located and peripheral towns.

    Science.gov (United States)

    Portnov, B A; Erell, E; Bivand, R; Nilsen, A

    2000-01-01

    In a previous study (Portnov and Erell, 1998a), an Index of Clustering was defined, which allowed an analysis of the combined effect of spatial isolation and remoteness of peripheral towns on the long-term patterns of their population growth. In the present paper, the analysis of the effect of clustering of the urban field on the patterns of population growth is extended to centrally located urban places, and the validity of this index is tested in two unevenly populated countries--Israel and Norway. In both countries, the effect of clustering of the urban field on the patterns of urban growth is twofold. In sparsely populated areas, the presence of neighboring towns appears to increase their chances of attracting potential migrants due to inter-urban exchanges, while in more densely populated areas, increasing clustering tends to reduce migration influx to a given locality due to inter-town competition. Following this conclusion, a strategy of "redirecting priorities" leading to the formation of urban clusters is proposed, which may enhance the potential of urban growth in geographical areas where this is desirable.

  3. Population effects of growth hormone transgenic coho salmon depend on food availability and genotype by environment interactions.

    Science.gov (United States)

    Devlin, Robert H; D'Andrade, Mark; Uh, Mitchell; Biagi, Carlo A

    2004-06-22

    Environmental risk assessment of genetically modified organisms requires determination of their fitness and invasiveness relative to conspecifics and other ecosystem members. Cultured growth hormone transgenic coho salmon (Oncorhynchus kisutch) have enhanced feeding capacity and growth, which can result in large enhancements in body size (>7-fold) relative to nontransgenic salmon, but in nature, the ability to compete for available food is a key factor determining survival fitness and invasiveness of a genotype. When transgenic and nontransgenic salmon were cohabitated and competed for different levels of food, transgenic salmon consistently outgrew nontransgenic fish and could affect the growth of nontransgenic cohorts except when food availability was high. When food abundance was low, dominant individuals emerged, invariably transgenic, that directed strong agonistic and cannibalistic behavior to cohorts and dominated the acquisition of limited food resources. When food availability was low, all groups containing transgenic salmon experienced population crashes or complete extinctions, whereas groups containing only nontransgenic salmon had good (72.0 +/- 4.3% SE) survival, and their population biomass continued to increase. Thus, effects of growth hormone transgenic salmon on experimental populations were primarily mediated by an interaction between food availability and population structure. These data, while indicative of forces which may act on natural populations, also underscore the importance of genotype by environment interactions in influencing risk assessment data for genetically modified organisms and suggest that, for species such as salmon which are derived from large complex ecosystems, considerable caution is warranted in applying data from individual studies.

  4. Vector population growth and condition-dependent movement drive the spread of plant pathogens.

    Science.gov (United States)

    Shaw, Allison K; Peace, Angela; Power, Alison G; Bosque-Pérez, Nilsa A

    2017-08-01

    Plant viruses, often spread by arthropod vectors, impact natural and agricultural ecosystems worldwide. Intuitively, the movement behavior and life history of vectors influence pathogen spread, but the relative contribution of each factor has not been examined. Recent research has highlighted the influence of host infection status on vector behavior and life history. Here, we developed a model to explore how vector traits influence the spread of vector-borne plant viruses. We allowed vector life history (growth rate, carrying capacity) and movement behavior (departure and settlement rates) parameters to be conditional on whether the plant host is infected or healthy and whether the vector is viruliferous (carrying the virus) or not. We ran simulations under a wide range of parameter combinations and quantified the fraction of hosts infected over time. We also ran case studies of the model for Barley yellow dwarf virus, a persistently transmitted virus, and for Potato virus Y, a non-persistently transmitted virus. We quantified the relative importance of each parameter on pathogen spread using Latin hypercube sampling with the statistical partial rank correlation coefficient technique. We found two general types of mechanisms in our model that increased the rate of pathogen spread. First, increasing factors such as vector intrinsic growth rate, carrying capacity, and departure rate from hosts (independent of whether these factors were condition-dependent) led to more vectors moving between hosts, which increased pathogen spread. Second, changing condition-dependent factors such as a vector's preference for settling on a host with a different infection status than itself, and vector tendency to leave a host of the same infection status, led to increased contact between hosts and vectors with different infection statuses, which also increased pathogen spread. Overall, our findings suggest that vector population growth rates had the greatest influence on rates of virus

  5. Genetic and environmental factors influencing the Placental Growth Factor (PGF variation in two populations.

    Directory of Open Access Journals (Sweden)

    Rossella Sorice

    Full Text Available Placental Growth Factor (PGF is a key molecule in angiogenesis. Several studies have revealed an important role of PGF primarily in pathological conditions (e.g.: ischaemia, tumour formation, cardiovascular diseases and inflammatory processes suggesting its use as a potential therapeutic agent. However, to date, no information is available regarding the genetics of PGF variability. Furthermore, even though the effect of environmental factors (e.g.: cigarette smoking on angiogenesis has been explored, no data on the influence of these factors on PGF levels have been reported so far. Here we have first investigated PGF variability in two cohorts focusing on non-genetic risk factors: a study sample from two isolated villages in the Cilento region, South Italy (N=871 and a replication sample from the general Danish population (N=1,812. A significant difference in PGF mean levels was found between the two cohorts. However, in both samples, we observed a strong correlation of PGF levels with ageing and sex, men displaying PGF levels significantly higher than women. Interestingly, smoking was also found to influence the trait in the two populations, although differently. We have then focused on genetic risk factors. The association between five single nucleotide polymorphisms (SNPs located in the PGF gene and the plasma levels of the protein was investigated. Two polymorphisms (rs11850328 and rs2268614 were associated with the PGF plasma levels in the Cilento sample and these associations were strongly replicated in the Danish sample. These results, for the first time, support the hypothesis of the presence of genetic and environmental factors influencing PGF plasma variability.

  6. Vascular endothelial growth factor gene polymorphisms in age-related macular degeneration in a Turkish population

    Directory of Open Access Journals (Sweden)

    Yunus Bulgu

    2014-10-01

    Full Text Available AIM:To assess the association between age-related macular degeneration (AMD and three single nucleotide polymorphisms (SNPs related to the vascular endothelial growth factor (VEGF gene.METHODS: The patients who were diagnosed with AMD were included in this prospective study. Three SNPs (rs1413711, rs2146323, and rs3025033 of the VEGF gene were genotyped by real-time polymerase chain reaction in the genomic DNA isolated from peripheral blood samples of the 82 patients and 80 controls.RESULTS: The genotype frequencies of rs1413711 and rs2146323 were not significantly different between the study group and the control group (P=0.072 and P=0.058. However, there was a significant difference in the genotype frequencies of these SNPs between the wet type AMD and dry type AMD (P=0.005 and P=0.010, respectively. One of the SNPs (rs1413711 was also found to be associated with the severity of AMD (P=0.001 with significant genotype distribution between early, intermediate, and advanced stages of the disease. The ancestral alleles were protective for both SNPs while the polymorphic alleles increased the risk for dry AMD.CONCLUSION: VEGF SNPs rs1413711 and rs2146323 polymorphisms are significantly associated with AMD subtypes in our population.

  7. Effects of population density on growth and production of Tilapia in monoculture

    Directory of Open Access Journals (Sweden)

    TH Majumder

    2017-12-01

    Full Text Available The experiment was conducted to determine the effect of population density on growth and production of Tilapia (monosex GIFT tilapia in monoculture system for a period of 110 days. The experiment was carried out in six earthen ponds, which were situated in the Bangladesh Agricultural University Campus, Mymensingh. The experiment was carried out under three treatments each with two replications. Fish population density was 200 fish per decimal under treatment-I, 400 fish per decimal under treatment-II and 600 fish per decimal under treatment-III. In the ponds supplementary feed of wheat bran and rice bran mixture were used daily at the rate of 46 g, 92 g and 136 g per decimal under treatment-I, II, and III, respectively. The average initial length and weight of tilapia were 4.63 cm and 2.82 g respectively. The ponds were fertilized fortnightly with urea and TSP at the rates of 60 g and 90 g, respectively. During experimental period, the ranges of water temperature (25.82 to 29.80 ºC, transparency (28.00 to 38.00 cm, dissolved oxygen (5.50 to 8.30 mg/L, pH (7.00 to 7.90, total alkalinity (130.00 to 200.00 mg/L, free CO2 (2.00 to 6.00 mg/L, phosphate-phosphorus (1.20 to 2.30 mg/L, and nitrate-nitrogen (3.20 to 4.00 mg/L were within the productive range and more or less similar in all the ponds under three treatments. There were 25 genera of phytoplankton under five major groups and 10 genera of zooplankton under three major groups in the experimental ponds. Mean survival rate of fish under treatment-I, treatment-II, and treatment-III were 82.75%, 77.12% and 74.33% respectively. The calculated net fish production under treatment-I was 6.75 ton/ha/yr and that of the ponds under treatment-II was 10.26 ton/ha/yr and that of the ponds under treatment-III was 12.15 ton/ha/yr. The net fish production under treatment-II and treatment-III were 152% and 180% higher than that of treatment-I, taking net fish production under treatment-I for 100%. According to

  8. New Venture, Survival, Growth : Continuance, Termination and Growth of Business Firms and Business Populations in Sweden During the 20th Century

    OpenAIRE

    Box, Marcus

    2005-01-01

    This dissertation focuses on the formation, growth and discontinuance of business populations and firms in Sweden during the 20th century. It addresses some key issues in the domain of economic and social sciences, and in particular entrepreneurship and small business research: if and when firms grow, stagnate and decline, as well as how long firms survive and when they are likely to disband. Previous research has primarily analyzed these questions from a short time frame. Further, an individ...

  9. Relationships of population growth and socio-economic development between satellite areas and the inner city--Taipei metropolitan case.

    Science.gov (United States)

    Tsai, H C

    1985-07-01

    This case study analyzes population growth and socioeconomic development in Taipei City and its satellite areas. Particular attention was devoted to 4 aspects: 1) population growth and industrial deconcentration in Taipei Metropolitan Area, 2) effects of population growth on demographic and socioeconomic changes in satellite areas, 3) effects of population and industrial growth in satellite areas on changes in the inner city, and 4) interrelationships between public services and facilities between the inner city and outlying areas. In 1968-82 the population of Taipei City increased 47%, from 1,579,346 to 2,327,641, and the population in industrialized satellite areas increased 127%, from 1,078,615 to 2,445,129. This trend reflects the 250% increase in the number of factories located in Taipei County in 1968-83. In the inner city, the number of factories increased by only 25% during this period. This pattern has increased the proportion of the population aged 25-39 years in satellite areas. In most of these areas, the industrial pattern has shifted from predominantly primary to largely secondary or tertiary. The total cultivated land mass in satellite areas has decreased dramatically. The total number of registered business companies and stores increased by 323% in Taipei City and by 243% in Taipei County in 1968-82. Household income increased more rapidly in the County than in the City, thereby decreasing the income gap between these 2 areas. It is expected that some of those living in satellite areas may later move to the inner city once their economic position has improved. Horticulture development in satellite areas has effectively supplied increasing consumption needs for fruit, vegetables, and flowers in the inner city. Transportation facilities, educational services, and hospitals are reciprocally used by residents of both areas. As the interdependence between Taipei City and County increases in the years ahead, there is a need to achieve greater cooperation

  10. Hybrid Rational Haar Wavelet and Block Pulse Functions Method for Solving Population Growth Model and Abel Integral Equations

    Directory of Open Access Journals (Sweden)

    E. Fathizadeh

    2017-01-01

    Full Text Available We use a computational method based on rational Haar wavelet for solving nonlinear fractional integro-differential equations. To this end, we apply the operational matrix of fractional integration for rational Haar wavelet. Also, to show the efficiency of the proposed method, we solve particularly population growth model and Abel integral equations and compare the numerical results with the exact solutions.

  11. Height-growth response to climatic changes differs among populations of Douglas-fir: A novel analysis of historic data

    Science.gov (United States)

    Laura P. Leites; Andrew P. Robinson; Gerald E. Rehfeldt; John D. Marshall; Nicholas L. Crookston

    2012-01-01

    Projected climate change will affect existing forests, as substantial changes are predicted to occur during their life spans. Species that have ample intraspecific genetic differentiation, such as Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), are expected to display population-specific growth responses to climate change. Using a mixed-effects modeling approach,...

  12. Southern (DisComfort?: Latino Population Growth, Economic Integration and Spatial Assimilation in North Carolina Micropolitan Areas

    Directory of Open Access Journals (Sweden)

    Ana-María González Wahl

    2007-10-01

    Full Text Available This paper examines more closely the growth and assimilation of the Latino population in non-metropolitan areas across North Carolina. More specifically, the analysis focuses on micropolitan areas. Based on the last decennial census, micropolitan areas were newly defined by the Census Bureau to reflect the growing importance of "urban clusters" located in non-metropolitan counties.

  13. Growth of Trichomycterus punctulatus “Life” in three population densities in intensive culture system with recirculation

    Directory of Open Access Journals (Sweden)

    Segundo Juan López Cubas

    2013-09-01

    Full Text Available The present research was conducted in order to determine the effect of population density on the growth of Trichomycterus punctulatus, in an intensive culture system with recirculation, to which was applied Increasing Stimulus Experimental Design with three treatments without repetition: 2.21 lifes / liter, 2.94 lifes / liter and 3.68 lifes / liter. The fish were fed a diet of 32% protein and were sampled monthly growth as well as physical and chemical parameters of the water. We applied ANOVA and Duncan test. Growth of T. punctulatus was affected by population density in direct, with a higher density of 3.68 lifes / liter: 90.90 mm and 5.95 g; also the overall production per cubic meter and observed the same trend. The physicochemical parameters of the water were similar among treatments and were within the ranges of good development for fish.

  14. Fetal growth curves for an ethnically diverse military population: the American Institute of Ultrasound in Medicine-accredited platform experience.

    Science.gov (United States)

    Elliott, Dawn; Patience, Troy; Boyd, Emily; Hume, Roderick F; Calhoun, Byron C; Napolitano, Peter G; Apodaca, Christina C

    2006-06-01

    To determine which fetal growth curve provided the best estimates of fetal weight for a cohort of ethnically diverse patients at sea level. The study consisted of a population of 1,729 fetuses examined at sea level between January 1, 1997, and June 30, 2000, at 18 weeks, 28 weeks, and term. Gestational age (GA) based on menstrual dates was confirmed or adjusted by crown-rump length or early second-trimester biometry. Fetal weight was estimated by using biparietal diameter, head circumference, abdominal circumference, and femur length. Our fetal growth curves were analyzed with fourth-order polynomial regression analysis, applying four previously defined formulae for fetal growth. Fetal growth curves for estimated fetal weight demonstrated the expected parabolic shape, which varied according to the formulae used. Our curve best fit the following equation: estimated fetal weight = 4.522 - 0.22 x GA age + 0.25 x GA(2) - 0.001 x GA(3) + 5.248 x 10(-6) x GA(4) (R2 = 0.976). SD increased in concordance with GA. Madigan Army Medical Center serves a racially mixed, culturally diverse, military community with unrestricted access to prenatal care. Determination of the optimal population-appropriate growth curve at the correct GA assists clinicians in identifying fetuses at risk for growth restriction or macrosomia and therefore at risk for increased perinatal morbidity and death.

  15. Numerical solution of a logistic growth model for a population with Allee effect considering fuzzy initial values and fuzzy parameters

    Science.gov (United States)

    Amarti, Z.; Nurkholipah, N. S.; Anggriani, N.; Supriatna, A. K.

    2018-03-01

    Predicting the future of population number is among the important factors that affect the consideration in preparing a good management for the population. This has been done by various known method, one among them is by developing a mathematical model describing the growth of the population. The model usually takes form in a differential equation or a system of differential equations, depending on the complexity of the underlying properties of the population. The most widely used growth models currently are those having a sigmoid solution of time series, including the Verhulst logistic equation and the Gompertz equation. In this paper we consider the Allee effect of the Verhulst’s logistic population model. The Allee effect is a phenomenon in biology showing a high correlation between population size or density and the mean individual fitness of the population. The method used to derive the solution is the Runge-Kutta numerical scheme, since it is in general regarded as one among the good numerical scheme which is relatively easy to implement. Further exploration is done via the fuzzy theoretical approach to accommodate the impreciseness of the initial values and parameters in the model.

  16. Age, growth and population structure of invasive lionfish (Pterois volitans/miles in northeast Florida using a length-based, age-structured population model

    Directory of Open Access Journals (Sweden)

    Eric G. Johnson

    2016-12-01

    Full Text Available The effective management of invasive species requires detailed understanding of the invader’s life history. This information is essential for modeling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Indo-Pacific lionfish (Pterois volitans/miles have rapidly invaded the western Atlantic, Gulf of Mexico and Caribbean Sea with documented negative impacts on native ecosystems. To better understand the life history of this species, we developed and validated a length-based, age-structured model to investigate age, growth and population structure in northeast Florida. The main findings of this study were: (1 lionfish exhibited rapid growth with seasonal variation in growth rates; (2 distinct cohorts were clearly identifiable in the length-frequency data, suggesting that lionfish are recruiting during a relatively short period in summer; and (3 the majority of lionfish were less than two years old with no lionfish older than three years of age, which may be the result of culling efforts as well as ontogenetic habitat shifts to deeper water.

  17. Life cycle and population growth rate of Caenorhabditis elegans studied by a new method

    Directory of Open Access Journals (Sweden)

    Schroeder Fabian

    2009-05-01

    Full Text Available Abstract Background The free-living nematode Caenorhabditis elegans is the predominant model organism in biological research, being used by a huge number of laboratories worldwide. Many researchers have evaluated life-history traits of C. elegans in investigations covering quite different aspects such as ecotoxicology, inbreeding depression and heterosis, dietary restriction/supplement, mutations, and ageing. Such traits include juvenile growth rates, age at sexual maturity, adult body size, age-specific fecundity/mortality, total reproduction, mean and maximum lifespan, and intrinsic population growth rates. However, we found that in life-cycle experiments care is needed regarding protocol design. Here, we test a recently developed method that overcomes some problems associated with traditional cultivation techniques. In this fast and yet precise approach, single individuals are maintained within hanging drops of semi-fluid culture medium, allowing the simultaneous investigation of various life-history traits at any desired degree of accuracy. Here, the life cycles of wild-type C. elegans strains N2 (Bristol, UK and MY6 (Münster, Germany were compared at 20°C with 5 × 109 Escherichia coli ml-1 as food source. Results High-resolution life tables and fecundity schedules of the two strains are presented. Though isolated 700 km and 60 years apart from each other, the two strains barely differed in life-cycle parameters. For strain N2 (n = 69, the intrinsic rate of natural increase (rmd-1, calculated according to the Lotka equation, was 1.375, the net reproductive rate (R0 291, the mean generation time (T 90 h, and the minimum generation time (Tmin 73.0 h. The corresponding values for strain MY6 (n = 72 were rm = 1.460, R0 = 289, T = 84 h, and Tmin = 67.3 h. Peak egg-laying rates in both strains exceeded 140 eggs d-1. Juvenile and early adulthood mortality was negligible. Strain N2 lived, on average, for 16.7 d, while strain MY6 died 2 days

  18. The Importance of Human Ecology at the Threshold of the Next Millennium: How Can Population Growth Be Stopped?

    Science.gov (United States)

    Nentwig, W.

    Ecology is defined as the set of complex interactions between the biotic and abiotic environments. Human ecology concerns principally the population ecology "only" of Homo sapiens, but it also includes all aspects of global ecology because humans are the most important species. Human demography is characterized by a recent decline in mortality and fertility rates. These demographic transitions have largely been completed in industrialized countries, but not in the 140 developing countries. Approximately 100 countries are following the same demographic pattern as industrialized countries, however with a time delay of several generations. China has effectively reduced its population increase by means that would be unacceptable in Western democracies. Some 44 developing countries still show increasing population growth and no detectable demographic transition in birth rate. Thus one part of the world shows limited (and, in the long run, shrinking) population growth, and another continues with a strong increase. All populations are limited in their development by their sustainability by their environment, for example, food and energy resources, and the extent of pollution which the use of these resources produces. It is argued that in the case of human population the limits of sustainability have already been reached with the 6 billion humans alive today, since at least 20% of these suffer from hunger, natural resources are overexploited, and biodiversity is threatened. In the coming 200years it is more likely that the total population will substantially oscillate rather than approach the predicted 12 billion. The most important goal of human ecology should therefore be to slow population growth as far as possible.

  19. Population growth of Varroa destructor (Acari: Varroidae) in commercial honey bee colonies treated with beta plant acids.

    Science.gov (United States)

    DeGrandi-Hoffman, Gloria; Ahumada, Fabiana; Curry, Robert; Probasco, Gene; Schantz, Lloyd

    2014-10-01

    Varroa (Varroa destuctor Anderson and Trueman) populations in honey bee (Apis mellifera L.) colonies might be kept at low levels by well-timed miticide applications. HopGuard(®) (HG) that contains beta plant acids as the active ingredient was used to reduce mite populations. Schedules for applications of the miticide that could maintain low mite levels were tested in hives started from either package bees or splits of larger colonies. The schedules were developed based on defined parameters for efficacy of the miticide and predictions of varroa population growth generated from a mathematical model of honey bee colony-varroa population dynamics. Colonies started from package bees and treated with HG in the package only or with subsequent HG treatments in the summer had 1.2-2.1 mites per 100 bees in August. Untreated controls averaged significantly more mites than treated colonies (3.3 mites per 100 bees). By October, mite populations ranged from 6.3 to 15.0 mites per 100 bees with the lowest mite numbers in colonies treated with HG in August. HG applications in colonies started from splits in April reduced mite populations to 0.12 mites per 100 bees. In September, the treated colonies had significantly fewer mites than the untreated controls. Subsequent HG applications in September that lasted for 3 weeks reduced mite populations to levels in November that were significantly lower than in colonies that were untreated or had an HG treatment that lasted for 1 week. The model accurately predicted colony population growth and varroa levels until the fall when varroa populations measured in colonies established from package bees or splits were much greater than predicted. Possible explanations for the differences between actual and predicted mite populations are discussed.

  20. Linking temporal changes in the demographic structure and individual growth to the decline in the population of a tropical fish

    Science.gov (United States)

    Sirot, Charlotte; Darnaude, Audrey M.; Guilhaumon, François; Ramos-Miranda, Julia; Flores-Hernandez, Domingo; Panfili, Jacques

    2015-11-01

    The exceptional biodiversity and productivity of tropical coastal lagoons can only be preserved by identifying the causes for the decline in the populations living in these vulnerable ecosystems. The Terminos lagoon in Mexico provided an opportunity for studying this issue as some of its fish populations, in particular the Silver Perch (Bairdiella chrysoura), have declined significantly since the 1980s. Fish sampling campaigns carried out over the whole lagoon area in 1979-81 and again in 2006-2011 revealed the mechanisms which may have been responsible for this decline. Based on biometrical data for 295 juveniles and adults from the two periods and on somatic growth derived from 173 otoliths, a study of the temporal changes in the demographic structure and life history traits (individual growth and body condition) made it possible to distinguish the causes of the decline in the B. chrysoura population. Growth models for the lagoon in 1980-1981 and 2006-2011 showed no significant change in the growth parameters of the population over the last 30 years with a logistic model giving an accurate estimate (R2 = 0.66) of the size-at-age for both periods. The decline in the B. chrysoura population could not be explained by an overall decrease in individual size and condition in the lagoon, the average standard length (SL) and Fulton index (FI) having increased slightly since 1980-1981 (4.6 mm and 0.02 for juveniles and 5.42 mm and 0.07 for adults). However, the size structure of the population in the lagoon has changed, with a significant shift in the size distribution of juveniles with a marked reduction in the proportion of juveniles ≤ 60 mm in the captures (90.9% fewer than in 1980-1981). As the otolith growth rate of fish during the first 4 months also decreased significantly between the two sampling periods (-15%), it is suggested that the main reason for the decline in the abundance and biomass of B. chrysoura within this system may be that its habitats are less

  1. Growth and physiological responses to cadmium stress of two populations of Dittrichia viscosa (L.) Greuter

    Energy Technology Data Exchange (ETDEWEB)

    Fernández, R.; Bertrand, A. [Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, Catedrático Rodrigo Uría s/n, 33071 Oviedo (Spain); Instituto Universitario de Biotecnología de Asturias (Spain); Reis, R.; Mourato, M.P.; Martins, L.L. [Departamento de Química Agrícola e Ambiental, Universidade Técnica de Lisboa, Tapada da Ajuda 1349-017, Lisboa (Portugal); González, A., E-mail: aidag@uniovi.es [Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, Catedrático Rodrigo Uría s/n, 33071 Oviedo (Spain); Instituto Universitario de Biotecnología de Asturias (Spain)

    2013-01-15

    Highlights: ► Cd tolerance and accumulation are constitutive traits in D. viscosa. ► The physiological mechanisms involved in Cd stress differed between clones. ► The metallicolous clone was more Cd tolerant than the non-metallicolous one. ► Antioxidant enzymes had important roles in each clone, especially peroxidases. -- Abstract: Two clones of Dittrichia viscosa (L.) Greuter from contrasting populations, DV-A (metallicolous) and DV-W (non-metallicolous), were studied to compare Cd accumulation and tolerance. After 10 days of hydroponic culture with 0, 5, 10, and 15 mg Cd L{sup −1}, metal accumulation and plant growth were measured as well as other stress markers such as decrease in the content of photosynthetic pigments, lipid peroxidation, phenols, H{sub 2}O{sub 2}, and free proline. We also analyzed the activity of the antioxidant enzymes guaiacol and ascorbate peroxidases, catalase, superoxide dismutase, and glutathione reductase as well as their isoform patterns. Our results confirmed a high Cd tolerance and accumulation in both clones of D. viscosa, which suggests that these traits are constitutive in this species. However, when the Cd concentration in solution exceeded 10 mg Cd L{sup −1}, DV-A was more tolerant than DV-W. The physiological mechanisms involved in Cd tolerance also differed between them, although phenols and guaiacol peroxidase played an important role in both clones. The effective Cd detoxification of DV-A consisted mainly in a promoted ascorbate peroxidase activity and better efficiency of catalase and glutathione reductase enzymes.

  2. Growth and physiological responses to cadmium stress of two populations of Dittrichia viscosa (L.) Greuter

    International Nuclear Information System (INIS)

    Fernández, R.; Bertrand, A.; Reis, R.; Mourato, M.P.; Martins, L.L.; González, A.

    2013-01-01

    Highlights: ► Cd tolerance and accumulation are constitutive traits in D. viscosa. ► The physiological mechanisms involved in Cd stress differed between clones. ► The metallicolous clone was more Cd tolerant than the non-metallicolous one. ► Antioxidant enzymes had important roles in each clone, especially peroxidases. -- Abstract: Two clones of Dittrichia viscosa (L.) Greuter from contrasting populations, DV-A (metallicolous) and DV-W (non-metallicolous), were studied to compare Cd accumulation and tolerance. After 10 days of hydroponic culture with 0, 5, 10, and 15 mg Cd L −1 , metal accumulation and plant growth were measured as well as other stress markers such as decrease in the content of photosynthetic pigments, lipid peroxidation, phenols, H 2 O 2 , and free proline. We also analyzed the activity of the antioxidant enzymes guaiacol and ascorbate peroxidases, catalase, superoxide dismutase, and glutathione reductase as well as their isoform patterns. Our results confirmed a high Cd tolerance and accumulation in both clones of D. viscosa, which suggests that these traits are constitutive in this species. However, when the Cd concentration in solution exceeded 10 mg Cd L −1 , DV-A was more tolerant than DV-W. The physiological mechanisms involved in Cd tolerance also differed between them, although phenols and guaiacol peroxidase played an important role in both clones. The effective Cd detoxification of DV-A consisted mainly in a promoted ascorbate peroxidase activity and better efficiency of catalase and glutathione reductase enzymes

  3. Growth, condition, and mortality of caribou (Rangifer tarandus groenlandicus in the Sisimiut Population, West Greenland

    Directory of Open Access Journals (Sweden)

    Vidar Holthe

    1984-05-01

    Full Text Available Growth and condition of the Sisimiut caribou was anlysed by means of mandible length, carcass weight, and back fat indices. Mandible lenght showed unchanged growth conditions since the late 1960s, and growth stops at 4 years of age. The Sisimiut caribou seems to be smaller than North American caribous, Greenlandic semi-domesticated reindeer and of same size or smaller than Scandinavian reindeer. Carcass weight showed similar results, however cow growth rate seems not to prolong sexual maturation. Back fat deposits were less than what is known from other reindeer and caribou populations. Sex and age distribution of mandibles from various materials and survival curves based on the same material shows — an uneven distribution between bulls and cows and a relatively large proportion of old cows in the bag from the last years, which seems to be caused by a light hunting pressure when the population peaked in the 1960s. Heavy natural mortality for animals born before or after a winter with unfavorable snow conditions was also showed.Vækst, kondition og dødelighed hos vildren (Rangifer tarandus groenlandicus i Sisimiut-bestanden, Vestgrønland.Abstract in Danish / Sammendrag: Vækst- og konditionsforhold for Sisimiut-vildrenbestanden i Vestgrønland er beskrevet ved hjæip af underkæbelængde, slagtevægt og rygfedt. Undersøgelsen af kæbelængde viste, at vækstforholdene havde været uforandret siden sidste halvdel af 1960-erne, at væksten standser ved 4-års alderen, samt at Sisimiut-vildrenen er mindre end de nordamerikanske caribou, Itinnera-tamrenen og på størrelse med eller mindre end skandinaviske rensdyr. Dette viste sig også ved sammenligninger af slagtevægt. Vægten af simlerne er dog ikke så ringe, at der kan iagttages nogen forsinkelse i kønsmodningen. Fedtreserverne ved indgangen til vinteren synes at være dårligere end i andre undersøgte rensdyrbestande. Køns- og aldersfordelingen blandt forskellige typer af indsamlet k

  4. Long-term data reveal a population decline of the tropical lizard Anolis apletophallus, and a negative affect of el nino years on population growth rate.

    Science.gov (United States)

    Stapley, Jessica; Garcia, Milton; Andrews, Robin M

    2015-01-01

    Climate change threatens biodiversity worldwide, however predicting how particular species will respond is difficult because climate varies spatially, complex factors regulate population abundance, and species vary in their susceptibility to climate change. Studies need to incorporate these factors with long-term data in order to link climate change to population abundance. We used 40 years of lizard abundance data and local climate data from Barro Colorado Island to ask how climate, total lizard abundance and cohort-specific abundance have changed over time, and how total and cohort-specific abundance relate to climate variables including those predicted to make the species vulnerable to climate change (i.e. temperatures exceeding preferred body temperature). We documented a decrease in lizard abundance over the last 40 years, and changes in the local climate. Population growth rate was related to the previous years' southern oscillation index; increasing following cooler-wetter, la niña years, decreasing following warmer-drier, el nino years. Within-year recruitment was negatively related to rainfall and minimum temperature. This study simultaneously identified climatic factors driving long-term population fluctuations and climate variables influencing short-term annual recruitment, both of which may be contributing to the population decline and influence the population's future persistence.

  5. Long-term data reveal a population decline of the tropical lizard Anolis apletophallus, and a negative affect of el nino years on population growth rate.

    Directory of Open Access Journals (Sweden)

    Jessica Stapley

    Full Text Available Climate change threatens biodiversity worldwide, however predicting how particular species will respond is difficult because climate varies spatially, complex factors regulate population abundance, and species vary in their susceptibility to climate change. Studies need to incorporate these factors with long-term data in order to link climate change to population abundance. We used 40 years of lizard abundance data and local climate data from Barro Colorado Island to ask how climate, total lizard abundance and cohort-specific abundance have changed over time, and how total and cohort-specific abundance relate to climate variables including those predicted to make the species vulnerable to climate change (i.e. temperatures exceeding preferred body temperature. We documented a decrease in lizard abundance over the last 40 years, and changes in the local climate. Population growth rate was related to the previous years' southern oscillation index; increasing following cooler-wetter, la niña years, decreasing following warmer-drier, el nino years. Within-year recruitment was negatively related to rainfall and minimum temperature. This study simultaneously identified climatic factors driving long-term population fluctuations and climate variables influencing short-term annual recruitment, both of which may be contributing to the population decline and influence the population's future persistence.

  6. Growth rate and rupture rate of unruptured intracranial aneurysms: a population approach

    Science.gov (United States)

    Jou, Liang-Der; Mawad, Michel E

    2009-01-01

    Background Understanding aneurysm growth rate allows us to predict not only the current rupture risk, but also accumulated rupture risk in the future. However, determining growth rate of unruptured intracranial aneurysms often requires follow-up of patients for a long period of time so that significant growth can be observed and measured. We investigate a relationship between growth rate and rupture rate and develop a theoretical model that can predict average behavior of unruptured intracranial aneurysms based on existing clinical data. Methods A mathematical model is developed that links growth rate and rupture rate. This model assumes a stable aneurysm size distribution so the number of aneurysm ruptures is balanced by the growth of aneurysms. Annual growth rates and growth profiles are calculated from a hypothetical size distribution and data from a previous clinical study. Results Our model predicts a growth rate of 0.34–1.63 mm/yr for three different growth models when the rupture rate at 10 mm is 1%. The growth rate is 0.56–0.65 mm/yr if annual rupture rate averaged over all aneurysm sizes is assumed to be 2%. The peak of aneurysm size distribution coincides with a period of slow growth between 5 mm and 8 mm. Conclusion This mathematical model can be used to predict aneurysm growth rate, and the results are consistent with previous clinical studies. Predictions from both hypothetical and clinical cases agree very well. This model explains why some aneurysms may grow into a stable size and remain so without rupture. PMID:19534830

  7. Variation in freshwater growth and development among five New England Atlantic salmon (Salmo salar) populations reared in a common environment

    Science.gov (United States)

    Obedzinski, M.; Letcher, B.H.

    2004-01-01

    We examined phenotypic variation in growth and development from the eyed-egg stage to the age-1+ smolt stage among five New England populations of Atlantic salmon (Salmo salar: East Machias, Narraguagus, Sheepscot, Penobscot, Connecticut) reared in a common laboratory environment. Study populations originated from rivers varying in size, latitude, and level of hatchery supplementation and included one reintroduced population (Connecticut was a recipient of Penobscot origin stock). Phenotypic trait differences were found among populations, and the degree of stock variation depended on ontogeny. Eggs were smaller and hatched sooner in the Penobscot (a northern, intensively managed population), but no stock differences were detected in size or growth efficiency from the onset of exogenous feeding to age 0+ summer. Differences again emerged in age 0+ autumn, with the degree of bimodality in length-frequency distributions differing among stocks; the Connecticut had the highest proportion of upper-mode fish and, ultimately, age-1+ smolts. Although genetic effects could not be entirely separated from maternal effects for egg size variation, it is likely that differences in hatch timing and smolt age had a genetic basis. Early emphasis on age-1+ hatchery-reared smolts in the Connecticut may have led to divergence in smolt age between the Penobscot and Connecticut populations in less than eight generations. ?? 2004 NRC Canada.

  8. Population differentiation for germination and early seedling root growth traits under saline conditions in the annual legume Medicago truncatula (Fabaceae).

    Science.gov (United States)

    Cordeiro, Matilde A; Moriuchi, Ken S; Fotinos, Tonya D; Miller, Kelsey E; Nuzhdin, Sergey V; von Wettberg, Eric J; Cook, Douglas R

    2014-03-01

    Seedling establishment and survival are highly sensitive to soil salinity and plants that evolved in saline environments are likely to express traits that increase fitness in those environments. Such traits are of ecological interest and they may have practical value for improving salt tolerance in cultivated species. We examined responses to soil salinity and tested potential mechanisms of salt tolerance in Medicago truncatula, using genotypes that originated from natural populations occurring on saline and nonsaline soils. Germination and seedling responses were quantified and compared between saline and nonsaline origin genotypes. Germination treatments included a range of sodium chloride (NaCl) concentrations in both offspring and parental environments. Seedling treatments included NaCl, abscisic acid (ABA), and potassium chloride (KCl). Saline origin genotypes displayed greater salinity tolerance for germination and seedling traits relative to nonsaline origin genotypes. We observed population specific differences for the effects of salinity on time to germination and for the impact of parental environment on germination rates. ABA and NaCl treatments had similar negative effects on root growth, although relative sensitivities differed, with saline population less sensitive to NaCl and more sensitive to ABA compared to their nonsaline counterparts. We report population differentiation for germination and seedling growth traits under saline conditions among populations derived from saline and nonsaline environments. These observations are consistent with a syndrome of adaptations for salinity tolerance during early plant development, including traits that are common among saline environments and those that are idiosyncratic to local populations.

  9. [Spatial pattern analysis and associations of Quercus aquifolioides population at different growth stages in Southeast Tibet, China].

    Science.gov (United States)

    Shen, Zhi-qiang; Hua, Min; Dan, Qu; Lu, Jie; Fang, Jiang-ping

    2016-02-01

    This article analyzed the spatial pattern and its correlation of Quercus aquifolioides, Southeast Tibet at different growing stages by using Ripley' s L function in the method of point pattern, analysis. The results showed the diameter structure of Q. aquifolioides population in Southeast Tibet followed a 'single peak' shape and the saplings and medium trees predominated in number in the whole population. The population had a high regeneration rate and was of increase type. In the growth process of Q. aquifolioides from saplings to large trees, saplings and medium trees showed aggregation distribution at.small scale, while large trees showed basically random distribution at whole scale. There was significant correlation between saplings with medium or large trees at small scale, however, there was no correlation between medium and large trees. In the growth process of Q. aquifolioides population from saplings, medium trees to large trees, its spatial pattern developed from aggregative distribution to random distribution. The natural regeneration of Q. aquifolioides population was affected not only by interspecific competition, but also by intraspecific competition. In the similar natural environment, the most important factors affecting the spatial pattern of Q. aquifoioides population were its own biological and ecological characteristics.

  10. Clonal variation in growth plasticity within a Bosmina longirostris population: the potential for resistance to toxic cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Xiaodong Jiang

    Full Text Available Many aquatic organisms respond phenotypically, through morphological, behavioral, and physiological plasticity, to environmental changes. The small-size cladoceran Bosminalongirostris, a dominant zooplankter in eutrophic waters, displayed reduced growth rates in response to the presence of a toxic cyanobacterium, Microcystisaeruginosa, in their diets. The magnitude of growth reduction differed among 15 clones recently isolated from a single population. A significant interaction between clone and food type indicated a genetic basis for the difference in growth plasticity. The variation in phenotypic plasticity was visualized by plotting reaction norms with two diets. The resistance of each clone to dietary cyanobacteria was measured as the relative change in growth rates on the "poor" diet compared with the "good" diet. The enhanced resistance to M. aeruginosa in B. longirostris was derived from both the reduced slope of reaction norms and the increased mean growth rates with two diets. The large clonal variation within a B. longirostris population may contribute to local adaptation to toxic cyanobacteria and influence ecosystem function via clonal succession.

  11. Growth during infancy and early childhood in children with cerebral palsy: a population-based study.

    Science.gov (United States)

    Strand, Kristin Melheim; Dahlseng, Magnus O; Lydersen, Stian; Rø, Torstein B; Finbråten, Ane-Kristine; Jahnsen, Reidun B; Andersen, Guro L; Vik, Torstein

    2016-09-01

    To describe growth in infancy and early childhood in children with cerebral palsy (CP). One hundred and four children with CP born at minimum 36 weeks' gestation in 2002 to 2010 were included. Prospectively collected growth data were requested from public health clinics. We calculated standard deviation (SD) scores (z-scores) for weight and height for 12 set age points for each child from birth to 5 years, and for head circumference from birth to 12 months. Children with CP had normal growth in weight and height if they were born non-small for gestational age (non-SGA) or had mild motor impairments (i.e. Gross Motor Function Classification System [GMFCS] I-II), whereas children born SGA or with severe motor impairments (GMFCS III-V) had reduced growth (pChildren with feeding difficulties in infancy had reduced growth in weight and height throughout early childhood, while children without feeding difficulties had normal growth. Head circumference growth decreased most severely among children born SGA, who had mean z-scores of -3.0 (95% confidence interval [CI] -3.7 to -2.2) at 1 year. Children with mild CP had normal growth in weight and height until 5 years, and in head circumference during infancy. Feeding difficulties in infancy and being born SGA were strongly associated with reduced growth. © 2016 Mac Keith Press.

  12. Nonencapsulated Streptococcus pneumoniae causes otitis media during single-species infection and during polymicrobial infection with nontypeable Haemophilus influenzae.

    Science.gov (United States)

    Murrah, Kyle A; Pang, Bing; Richardson, Stephen; Perez, Antonia; Reimche, Jennifer; King, Lauren; Wren, John; Swords, W Edward

    2015-07-01

    Streptococcus pneumoniae strains lacking capsular polysaccharide have been increasingly reported in carriage and disease contexts. Since most cases of otitis media involve more than one bacterial species, we aimed to determine the capacity of a nonencapsulated S. pneumoniae clinical isolate to induce disease in the context of a single-species infection and as a polymicrobial infection with nontypeable Haemophilus influenzae. Using the chinchilla model of otitis media, we found that nonencapsulated S. pneumoniae colonizes the nasopharynx following intranasal inoculation, but does not readily ascend into the middle ear. However, when we inoculated nonencapsulated S. pneumoniae directly into the middle ear, the bacteria persisted for two weeks post-inoculation and induced symptoms consistent with chronic otitis media. During coinfection with nontypeable H. influenzae, both species persisted for one week and induced polymicrobial otitis media. We also observed that nontypeable H. influenzae conferred passive protection from killing by amoxicillin upon S. pneumoniae from within polymicrobial biofilms in vitro. Therefore, based on these results, we conclude that nonencapsulated pneumococci are a potential causative agent of chronic/recurrent otitis media, and can also cause mutualistic infection with other opportunists, which could complicate treatment outcomes. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Epidemiological survey in single-species flocks from Poland reveals expanded genetic and antigenic diversity of small ruminant lentiviruses

    Science.gov (United States)

    Valas, Stephen; Kuźmak, Jacek

    2018-01-01

    Small ruminant lentivirus (SRLV) infections are widespread in Poland and circulation of subtypes A1, A12, A13, B1 and B2 was detected. The present work aimed at extending previous study based on the analysis of a larger number of animals from single-species flocks. Animals were selected for genetic analysis based on serological reactivity towards a range of recombinant antigens derived from Gag and Env viral proteins. Phylogenetic analysis revealed the existence of subtypes B2 and A12 in both goats and sheep and subtypes A1 and B1 in goats only. In addition, two novel subtypes, A16 and A17, were found in goats. Co-infections with strains belonging to different subtypes within A and B groups were detected in 1 sheep and 4 goats originating from four flocks. Although the reactivity of serum samples towards the recombinant antigens confirmed immunological relatedness between Gag epitopes of different subtypes and the cross-reactive nature of Gag antibodies, eleven serum samples failed to react with antigens representing all subtypes detected up-to-date in Poland, highlighting the limitations of the serological diagnosis. These data showed the complex nature of SRLV subtypes circulating in sheep and goats in Poland and the need for improving SRLV-related diagnostic capacity. PMID:29505612

  14. Future coastal population growth and exposure to sea-level rise and coastal flooding--a global assessment.

    Directory of Open Access Journals (Sweden)

    Barbara Neumann

    Full Text Available Coastal zones are exposed to a range of coastal hazards including sea-level rise with its related effects. At the same time, they are more densely populated than the hinterland and exhibit higher rates of population growth and urbanisation. As this trend is expected to continue into the future, we investigate how coastal populations will be affected by such impacts at global and regional scales by the years 2030 and 2060. Starting from baseline population estimates for the year 2000, we assess future population change in the low-elevation coastal zone and trends in exposure to 100-year coastal floods based on four different sea-level and socio-economic scenarios. Our method accounts for differential growth of coastal areas against the land-locked hinterland and for trends of urbanisation and expansive urban growth, as currently observed, but does not explicitly consider possible displacement or out-migration due to factors such as sea-level rise. We combine spatially explicit estimates of the baseline population with demographic data in order to derive scenario-driven projections of coastal population development. Our scenarios show that the number of people living in the low-elevation coastal zone, as well as the number of people exposed to flooding from 1-in-100 year storm surge events, is highest in Asia. China, India, Bangladesh, Indonesia and Viet Nam are estimated to have the highest total coastal population exposure in the baseline year and this ranking is expected to remain largely unchanged in the future. However, Africa is expected to experience the highest rates of population growth and urbanisation in the coastal zone, particularly in Egypt and sub-Saharan countries in Western and Eastern Africa. The results highlight countries and regions with a high degree of exposure to coastal flooding and help identifying regions where policies and adaptive planning for building resilient coastal communities are not only desirable but essential

  15. Future coastal population growth and exposure to sea-level rise and coastal flooding--a global assessment.

    Science.gov (United States)

    Neumann, Barbara; Vafeidis, Athanasios T; Zimmermann, Juliane; Nicholls, Robert J

    2015-01-01

    Coastal zones are exposed to a range of coastal hazards including sea-level rise with its related effects. At the same time, they are more densely populated than the hinterland and exhibit higher rates of population growth and urbanisation. As this trend is expected to continue into the future, we investigate how coastal populations will be affected by such impacts at global and regional scales by the years 2030 and 2060. Starting from baseline population estimates for the year 2000, we assess future population change in the low-elevation coastal zone and trends in exposure to 100-year coastal floods based on four different sea-level and socio-economic scenarios. Our method accounts for differential growth of coastal areas against the land-locked hinterland and for trends of urbanisation and expansive urban growth, as currently observed, but does not explicitly consider possible displacement or out-migration due to factors such as sea-level rise. We combine spatially explicit estimates of the baseline population with demographic data in order to derive scenario-driven projections of coastal population development. Our scenarios show that the number of people living in the low-elevation coastal zone, as well as the number of people exposed to flooding from 1-in-100 year storm surge events, is highest in Asia. China, India, Bangladesh, Indonesia and Viet Nam are estimated to have the highest total coastal population exposure in the baseline year and this ranking is expected to remain largely unchanged in the future. However, Africa is expected to experience the highest rates of population growth and urbanisation in the coastal zone, particularly in Egypt and sub-Saharan countries in Western and Eastern Africa. The results highlight countries and regions with a high degree of exposure to coastal flooding and help identifying regions where policies and adaptive planning for building resilient coastal communities are not only desirable but essential. Furthermore, we

  16. Future Coastal Population Growth and Exposure to Sea-Level Rise and Coastal Flooding - A Global Assessment

    Science.gov (United States)

    Neumann, Barbara; Vafeidis, Athanasios T.; Zimmermann, Juliane; Nicholls, Robert J.

    2015-01-01

    Coastal zones are exposed to a range of coastal hazards including sea-level rise with its related effects. At the same time, they are more densely populated than the hinterland and exhibit higher rates of population growth and urbanisation. As this trend is expected to continue into the future, we investigate how coastal populations will be affected by such impacts at global and regional scales by the years 2030 and 2060. Starting from baseline population estimates for the year 2000, we assess future population change in the low-elevation coastal zone and trends in exposure to 100-year coastal floods based on four different sea-level and socio-economic scenarios. Our method accounts for differential growth of coastal areas against the land-locked hinterland and for trends of urbanisation and expansive urban growth, as currently observed, but does not explicitly consider possible displacement or out-migration due to factors such as sea-level rise. We combine spatially explicit estimates of the baseline population with demographic data in order to derive scenario-driven projections of coastal population development. Our scenarios show that the number of people living in the low-elevation coastal zone, as well as the number of people exposed to flooding from 1-in-100 year storm surge events, is highest in Asia. China, India, Bangladesh, Indonesia and Viet Nam are estimated to have the highest total coastal population exposure in the baseline year and this ranking is expected to remain largely unchanged in the future. However, Africa is expected to experience the highest rates of population growth and urbanisation in the coastal zone, particularly in Egypt and sub-Saharan countries in Western and Eastern Africa. The results highlight countries and regions with a high degree of exposure to coastal flooding and help identifying regions where policies and adaptive planning for building resilient coastal communities are not only desirable but essential. Furthermore, we

  17. Genetic variation for growth rate, feed conversion efficiency, and disease resistance exists within a farmed population of rainbow trout

    DEFF Research Database (Denmark)

    Henryon, Mark; Jokumsen, Alfred; Berg, Peer

    2002-01-01

    The objective of this study was to test that additive genetic (co)variation for survival, growth rate, feed conversion efficiency, and resistance to viral haemorrhagic septicaemia (VHS) exists within a farmed population of rainbow trout. Thirty sires and 30 dams were mated by a partly factorial...... the predicted breeding values for VHS resistance and the predicted breeding values for the body weights, body length, and feed conversion efficiencies. These results demonstrate that additive genetic (co)variation for growth rate, feed conversion efficiency, and VHS resistance does exist within the farmed...

  18. The effects of population growth on timber management and inventories in Virginia

    Science.gov (United States)

    David N. Wear; Rei Liu; J. Michael Foreman; Raymond M. Sheffield

    1999-01-01

    Expanding human populations may have important effects on the availability of timber from private lands in the South. To examine the effects of development on timber supply, the authors compared the density of populations and various site variables with expert opinions on the future location of commercial timberland for a study site in Virginia. Population density is a...

  19. A highly variable segment of human subterminal 16p reveals a history of population growth for modern humans outside Africa

    Science.gov (United States)

    Alonso, Santos; Armour, John A. L.

    2001-01-01

    We have sequenced a highly polymorphic subterminal noncoding region from human chromosome 16p13.3, flanking the 5′ end of the hypervariable minisatellite MS205, in 100 chromosomes sampled from different African and Euroasiatic populations. Coalescence analysis indicates that the time to the most recent common ancestor (approximately 1 million years) predates the appearance of anatomically modern human forms. The root of the network describing this variability lies in Africa. African populations show a greater level of diversity and deeper branches. Most Euroasiatic variability seems to have been generated after a recent out-of-Africa range expansion. A history of population growth is the most likely scenario for the Euroasiatic populations. This pattern of nuclear variability can be reconciled with inferences based on mitochondrial DNA. PMID:11158547

  20. Quantitative trait local analysis of growth-related traits in a new Arabidopsis recombinant inbred population

    NARCIS (Netherlands)

    El-Lithy, M.E.M.; Clerkx, E.J.M.; Ruijs, G.J.; Koornneef, M.; Vreugdenhil, D.

    2004-01-01

    Arabidopsis natural variation was used to analyze the genetics of plant growth rate. Screening of 22 accessions revealed a large variation for seed weight, plant dry weight and relative growth rate but not for water content. A positive correlation was observed between seed weight and plant area 10 d

  1. Water availability and population origin affect the expression of the tradeoff between reproduction and growth in Plantago coronopus.

    Science.gov (United States)

    Hansen, C F; García, M B; Ehlers, B K

    2013-05-01

    Investment in reproduction and growth represent a classic tradeoff with implication for life history evolution. The local environment can play a major role in the magnitude and evolutionary consequences of such a tradeoff. Here, we examined the investment in reproductive and vegetative tissue in 40 maternal half-sib families from four different populations of the herb Plantago coronopus growing in either a dry or wet greenhouse environment. Plants originated from populations with an annual or a perennial life form, with annuals prevailing in drier habitats with greater seasonal variation in both temperature and precipitation. We found that water availability affected the expression of the tradeoff (both phenotypic and genetic) between reproduction and growth, being most accentuated under dry condition. However, populations responded very differently to water treatments. Plants from annual populations showed a similar response to drought condition with little variation among maternal families, suggesting a history of selection favouring genotypes with high allocation to reproduction when water availability is low. Plants from annual populations also expressed the highest level of plasticity. For the perennial populations, one showed a large variation among maternal families in resource allocation and expressed significant negative genetic correlations between reproductive and vegetative biomass under drought. The other perennial population showed less variation in response to treatment and had trait values similar to those of the annuals, although it was significantly less plastic. We stress the importance of considering intraspecific variation in response to environmental change such as drought, as conspecific plants exhibited very different abilities and strategies to respond to high versus low water availability even among geographically close populations. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  2. Increasing cell culture population doublings for long-term growth of finite life span human cell cultures

    Science.gov (United States)

    Stampfer, Martha R; Garbe, James C

    2015-02-24

    Cell culture media formulations for culturing human epithelial cells are herein described. Also described are methods of increasing population doublings in a cell culture of finite life span human epithelial cells and prolonging the life span of human cell cultures. Using the cell culture media disclosed alone and in combination with addition to the cell culture of a compound associated with anti-stress activity achieves extended growth of pre-stasis cells and increased population doublings and life span in human epithelial cell cultures.

  3. Macrophage Ablation Reduces M2-Like Populations and Jeopardizes Tumor Growth in a MAFIA-Based Glioma Model12

    Science.gov (United States)

    Gabrusiewicz, Konrad; Hossain, Mohammad B.; Cortes-Santiago, Nahir; Fan, Xuejun; Kaminska, Bozena; Marini, Frank C.; Fueyo, Juan; Gomez-Manzano, Candelaria

    2015-01-01

    Monocytes/macrophages are an influential component of the glioma microenvironment. However, understanding their diversity and plasticity constitute one of the most challenging areas of research due to the paucity of models to study these cells' inherent complexity. Herein, we analyzed the role of monocytes/macrophages in glioma growth by using a transgenic model that allows for conditional ablation of this cell population. We modeled glioma using intracranial GL261-bearing CSF-1R–GFP+ macrophage Fas-induced apoptosis (MAFIA) transgenic mice. Conditional macrophage ablation was achieved by exposure to the dimerizer AP20187. Double immunofluorescence was used to characterize M1- and M2-like monocytes/macrophages during tumor growth and after conditional ablation. During glioma growth, the monocyte/macrophage population consisted predominantly of M2 macrophages. Conditional temporal depletion of macrophages reduced the number of GFP+ cells, targeting mainly the repopulation of M2-polarized cells, and altered the appearance of M1-like monocytes/macrophages, which suggested a shift in the M1/M2 macrophage balance. Of interest, compared with control-treated mice, macrophage-depleted mice had a lower tumor mitotic index, microvascular density, and reduced tumor growth. These results demonstrated the possibility of studying in vivo the role and phenotype of macrophages in gliomas and suggested that transitory depletion of CSF-1R+ population influences the reconstitutive phenotypic pool of these cells, ultimately suppressing tumor growth. The MAFIA model provides a much needed advance in defining the role of macrophages in gliomas. PMID:25925380

  4. Macrophage Ablation Reduces M2-Like Populations and Jeopardizes Tumor Growth in a MAFIA-Based Glioma Model.

    Science.gov (United States)

    Gabrusiewicz, Konrad; Hossain, Mohammad B; Cortes-Santiago, Nahir; Fan, Xuejun; Kaminska, Bozena; Marini, Frank C; Fueyo, Juan; Gomez-Manzano, Candelaria

    2015-04-01

    Monocytes/macrophages are an influential component of the glioma microenvironment. However, understanding their diversity and plasticity constitute one of the most challenging areas of research due to the paucity of models to study these cells' inherent complexity. Herein, we analyzed the role of monocytes/macrophages in glioma growth by using a transgenic model that allows for conditional ablation of this cell population. We modeled glioma using intracranial GL261-bearing CSF-1R-GFP(+) macrophage Fas-induced apoptosis (MAFIA) transgenic mice. Conditional macrophage ablation was achieved by exposure to the dimerizer AP20187. Double immunofluorescence was used to characterize M1- and M2-like monocytes/macrophages during tumor growth and after conditional ablation. During glioma growth, the monocyte/macrophage population consisted predominantly of M2 macrophages. Conditional temporal depletion of macrophages reduced the number of GFP(+) cells, targeting mainly the repopulation of M2-polarized cells, and altered the appearance of M1-like monocytes/macrophages, which suggested a shift in the M1/M2 macrophage balance. Of interest, compared with control-treated mice, macrophage-depleted mice had a lower tumor mitotic index, microvascular density, and reduced tumor growth. These results demonstrated the possibility of studying in vivo the role and phenotype of macrophages in gliomas and suggested that transitory depletion of CSF-1R(+) population influences the reconstitutive phenotypic pool of these cells, ultimately suppressing tumor growth. The MAFIA model provides a much needed advance in defining the role of macrophages in gliomas. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  5. The Environmental Consequences of Altered Nitrogen Cycling Resulting from Industrial Activity, Agricultural Production, and Population Growth in China

    OpenAIRE

    Xing, G.X.; Zhu, Z.L.

    2001-01-01

    Human activities exerted very little effect on nitrogen (N) cycling in China before 1949. Between 1949 and 1999, however, rapid economic development and population growth led to dramatic changes in anthropogenic reactive N, inputted recycling N, N flux on land, N2O emission, and NH3 volatilization. Consequently, these changes have had a tremendous impact on the environment in China. In the current study, we estimated the amount of atmospheric wet N deposition and N transportation into water b...

  6. In a long-term experimental demography study, excluding ungulates reversed invader's explosive population growth rate and restored natives.

    Science.gov (United States)

    Kalisz, Susan; Spigler, Rachel B; Horvitz, Carol C

    2014-03-25

    A major goal in ecology is to understand mechanisms that increase invasion success of exotic species. A recent hypothesis implicates altered species interactions resulting from ungulate herbivore overabundance as a key cause of exotic plant domination. To test this hypothesis, we maintained an experimental demography deer exclusion study for 6 y in a forest where the native ungulate Odocoileus virginianus (white-tailed deer) is overabundant and Alliaria petiolata (garlic mustard) is aggressively invading. Because population growth is multiplicative across time, we introduce metrics that correctly integrate experimental effects across treatment years, the cumulative population growth rate, λc, and its geometric mean, λper-year, the time-averaged annual population growth rate. We determined λc and λper-year of the invader and of a common native, Trillium erectum. Our results conclusively demonstrate that deer are required for the success of Alliaria; its projected population trajectory shifted from explosive growth in the presence of deer (λper-year = 1.33) to decline toward extinction where deer are excluded (λper-year = 0.88). In contrast, Trillium's λper-year was suppressed in the presence of deer relative to deer exclusion (λper-year = 1.04 vs. 1.20, respectively). Retrospective sensitivity analyses revealed that the largest negative effect of deer exclusion on Alliaria came from rosette transitions, whereas the largest positive effect on Trillium came from reproductive transitions. Deer exclusion lowered Alliaria density while increasing Trillium density. Our results provide definitive experimental support that interactions with overabundant ungulates enhance demographic success of invaders and depress natives' success, with broad implications for biodiversity and ecosystem function worldwide.

  7. Effects of Stochasticity in Early Life History on Steepness and Population Growth Rate Estimates: An Illustration on Atlantic Bluefin Tuna

    Science.gov (United States)

    Simon, Maximilien; Fromentin, Jean-Marc; Bonhommeau, Sylvain; Gaertner, Daniel; Brodziak, Jon; Etienne, Marie-Pierre

    2012-01-01

    The intrinsic population growth rate (r) of the surplus production function used in the biomass dynamic model and the steepness (h) of the stock-recruitment relationship used in age-structured population dynamics models are two key parameters in fish stock assessment. There is generally insufficient information in the data to estimate these parameters that thus have to be constrained. We developed methods to directly estimate the probability distributions of r and h for the Atlantic bluefin tuna (Thunnus thynnus, Scombridae), using all available biological and ecological information. We examined the existing literature to define appropriate probability distributions of key life history parameters associated with intrinsic growth rate and steepness, paying particular attention to the natural mortality for early life history stages. The estimated probability distribution of the population intrinsic growth rate was weakly informative, with an estimated mean r = 0.77 (±0.53) and an interquartile range of (0.34, 1.12). The estimated distribution of h was more informative, but also strongly asymmetric with an estimated mean h = 0.89 (±0.20) and a median of 0.99. We note that these two key demographic parameters strongly depend on the distribution of early life history mortality rate (M0), which is known to exhibit high year-to-year variations. This variability results in a widely spread distribution of M0 that affects the distribution of the intrinsic population growth rate and further makes the spawning stock biomass an inadequate proxy to predict recruitment levels. PMID:23119063

  8. Effects of stochasticity in early life history on steepness and population growth rate estimates: an illustration on Atlantic bluefin tuna.

    Directory of Open Access Journals (Sweden)

    Maximilien Simon

    Full Text Available The intrinsic population growth rate (r of the surplus production function used in the biomass dynamic model and the steepness (h of the stock-recruitment relationship used in age-structured population dynamics models are two key parameters in fish stock assessment. There is generally insufficient information in the data to estimate these parameters that thus have to be constrained. We developed methods to directly estimate the probability distributions of r and h for the Atlantic bluefin tuna (Thunnus thynnus, Scombridae, using all available biological and ecological information. We examined the existing literature to define appropriate probability distributions of key life history parameters associated with intrinsic growth rate and steepness, paying particular attention to the natural mortality for early life history stages. The estimated probability distribution of the population intrinsic growth rate was weakly informative, with an estimated mean r = 0.77 (±0.53 and an interquartile range of (0.34, 1.12. The estimated distribution of h was more informative, but also strongly asymmetric with an estimated mean h = 0.89 (±0.20 and a median of 0.99. We note that these two key demographic parameters strongly depend on the distribution of early life history mortality rate (M(0, which is known to exhibit high year-to-year variations. This variability results in a widely spread distribution of M(0 that affects the distribution of the intrinsic population growth rate and further makes the spawning stock biomass an inadequate proxy to predict recruitment levels.

  9. Maturity and growth population dynamics of Norway pout (Trisopterus esmarkii) in the North Sea, Skagerrak, and Kattegat

    DEFF Research Database (Denmark)

    Lambert, Gwladys; Nielsen, J. Rasmus; Larsen, Lena I.

    2009-01-01

    The population dynamics of the Norway pout stock in the North Sea are investigated by statistical analyses, and GIS of ICES International Bottom Trawl Surveys (IBTS) and Danish commercial catch data from 1983 to 2006. The stock spawns mainly around mid-February along the northeastern English...... should be taken into account when estimating spawning-stock biomass in routine assessments. Growth is also variable, with a tendency for male maximum length to be smaller than that of females, and immature fish to be smaller than mature ones in each age group. The juvenile growth rate is higher when...... the stock density is low and results in a reduced age-at-50%-maturity. Besides these intraspecific patterns, the growth rates show interspecific links to stock sizes of the important predators: cod, haddock, and whiting....

  10. Genetic variation for growth rate, feed conversion efficiency, and disease resistance exists within a farmed population of rainbow trout

    DEFF Research Database (Denmark)

    Henryon, Mark; Jokumsen, Alfred; Berg, Peer

    2002-01-01

    The objective of this study was to test that additive genetic (co)variation for survival, growth rate, feed conversion efficiency, and resistance to viral haemorrhagic septicaemia (VHS) exists within a farmed population of rainbow trout. Thirty sires and 30 dams were mated by a partly factorial...... mating design. Each sire was mated to two dams, and each dam was mated to two sires, producing 50 viable full-sib families (29 sires, 25 dams). The fish from these families were reared for a 215-day growout period, and were assessed for survival between days 52 and 215, growth rate (i.e., body weight...... the predicted breeding values for VHS resistance and the predicted breeding values for the body weights, body length, and feed conversion efficiencies. These results demonstrate that additive genetic (co)variation for growth rate, feed conversion efficiency, and VHS resistance does exist within the farmed...

  11. Growth, size and age at maturity of the agile frog (Rana dalmatina) in an Iberian Peninsula population.

    Science.gov (United States)

    Sarasola-Puente, Vanessa; Gosá, Alberto; Oromí, Neus; Madeira, María José; Lizana, Miguel

    2011-06-01

    The mean age of a population of agile frogs (Rana dalmatina) from the Iberian Peninsula was estimated using mark and recapture and skeletochronology. Life-history parameters, including growth rate, body length, age and size at maturity, sexual dimorphism and longevity, were studied. The regression between age and snout-vent length (SVL) was highly significant in both sexes. Males reached sexual maturity at two years of age, although sometimes they can reach it at only one year of age. The average SVL at maturity was 51.75 mm (standard error (SE)=0.71; n=45). Females reached sexual maturity at two years of age with an average SVL of 62.14 mm (SE=2.20; n=14). A subset of the female population reached sexual maturity at three years of age. Growth was rapid until sexual maturity was reached. There was an overlap of SVL between different age classes. Growth was continuous, fulfilling the conditions of Von Bertalanffy's model. The growth coefficient (K) was 0.840 in males and 0.625 in females. The maximum SVL was greater in females (73.00 mm) than in males (59.50mm). Sexual dimorphism was significantly biased towards females in all age classes. The maximum longevity observed was 6 years in females and 8 years in males. Management strategies for agile frogs should take into account factors such as these life-history characteristics. Copyright © 2011 Elsevier GmbH. All rights reserved.

  12. Population Growth, Migration, and Changes in the Racial Differential in Imprisonment in the United States, 1940–1980

    Directory of Open Access Journals (Sweden)

    David J. Harding

    2016-07-01

    Full Text Available The proportion of U.S. prison inmates who were black increased dramatically between 1940 and 2000. While about two-thirds of the increase occurred between 1940 and 1970, most recent research analyzes the period after 1970, focusing on explanations such as the war on drugs, law-and-order politics, discrimination, inequality, and racial threat. We analyze the growth in the racial difference in incarceration between 1940 and 1980, focusing on the role of demographic processes, particularly population growth, migration, and urbanization. We implement three analyses to assess the role of these demographic processes: (1 a simple accounting model that decomposes the national trend into population growth, changes in arrests, and changes in sentencing; (2 a model of state variation in incarceration that decomposes the racial difference in incarceration into population change, migration between states with different incarceration rates, and other processes; and (3 race-specific models of within-state variation in incarceration rates using state characteristics coupled with a decomposition of the role of changes in state characteristics.

  13. Herbivory and growth in terrestrial and aquatic populations of amphibious stream plants

    DEFF Research Database (Denmark)

    Sand-Jensen, Kaj; Jacobsen, Dean

    2002-01-01

    to evaluate advantages and disadvantages of aerial and submerged life. 2. Terrestrial populations had higher area shoot density, biomass and leaf production than aquatic populations, while leaf turnover rate and longevity were the same. Terrestrial populations experienced lower percentage grazing loss of leaf...... production (average 1.2-5.1%) than aquatic populations (2.9-17.3%), while the same plant dry mass was consumed per unit ground area. 3. Grazing loss increased linearly with leaf age apart from the youngest leaf stages. Grazing loss during the lifetime of leaves was therefore 2.4-3.1 times higher than mean...

  14. Implementing ecosystem-based fisheries management: from single-species to integrated ecosystem assessment and advice for Baltic Sea fish stocks

    DEFF Research Database (Denmark)

    Möllmann, Christian; Lindegren, Martin; Blenckner, Thorsten

    2014-01-01

    Theory behind ecosystem-based management (EBM) and ecosystem-based fisheries management (EBFM) is nowwell developed. However, the implementation of EBFM exemplified by fisheries management in Europe is still largely based on single-species assessments and ignores the wider ecosystem context and i...

  15. In situ growth rates and biofilm development of Pseudomonas aeruginosa populations in chronic lung infections

    DEFF Research Database (Denmark)

    Yang, L.; Haagensen, J.A.; Jelsbak, L.

    2008-01-01

    The growth dynamics of bacterial pathogens within infected hosts are a fundamental but poorly understood feature of most infections. We have focused on the in situ distribution and growth characteristics of two prevailing and transmissible Pseudomonas aeruginosa clones that have caused chronic lung...... matrix, whereas nonmucoid variants were present mainly as dispersed cells. To obtain estimates of the growth rates of P. aeruginosa in CF lungs, we used quantitative FISH to indirectly measure growth rates of bacteria in sputum samples (reflecting the in vivo lung conditions). The concentration of r......RNA in bacteria isolated from sputa was measured and correlated with the rRNA contents of the same bacteria growing in vitro at defined rates. The results showed that most cells were actively growing with doubling times of between 100 and 200 min, with some growing even faster. Only a small stationary...

  16. In situ growth rates and biofilm development of Pseudomonas aeruginosa populations in chronic lung infections

    DEFF Research Database (Denmark)

    Yang, L.; Haagensen, J.A.; Jelsbak, L.

    2008-01-01

    matrix, whereas nonmucoid variants were present mainly as dispersed cells. To obtain estimates of the growth rates of P. aeruginosa in CF lungs, we used quantitative FISH to indirectly measure growth rates of bacteria in sputum samples (reflecting the in vivo lung conditions). The concentration of r......The growth dynamics of bacterial pathogens within infected hosts are a fundamental but poorly understood feature of most infections. We have focused on the in situ distribution and growth characteristics of two prevailing and transmissible Pseudomonas aeruginosa clones that have caused chronic lung......RNA in bacteria isolated from sputa was measured and correlated with the rRNA contents of the same bacteria growing in vitro at defined rates. The results showed that most cells were actively growing with doubling times of between 100 and 200 min, with some growing even faster. Only a small stationary...

  17. Effect of dispersants on the growth of indigenous bacterial population and biodegradation of crude oil

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Row, A.

    Oil dispersants (5 from Castrol Ltd., Bombay and 2 from British Petroleum, London) were studied individually and in combination with Saudi Arabian crude oil for their effect on the growth of indigenous bacteria and on the biodegradation of oil. None...

  18. Genetic improvement on Chinese shrimp ( Fenneropenaeus chinensis): growth and viability performance in F1 hybrids of different populations

    Science.gov (United States)

    Tian, Yi; Kong, Jie; Li, Wendong; Luan, Sheng; Yang, Cuihua; Wang, Qingyin

    2008-11-01

    Fenneropenaeus chinensis distributed in the Yellow Sea and Bohai Sea of China and the west coast of the Korean Peninsula. Different geographical populations represent potentially different genetic resources. To learn further the characteristics of different geographical population, crosses among two wild and three farmed populations were produced. The two wild populations were from the Yellow Sea and Bohai Sea (WYP), and the west coast of the Korean Peninsula and coast (WKN). The three farmed populations included the offspring of first generation of wild shrimp from coast in Korea (FKN), the Huang Hai (the Yellow Sea in Chinese) No.1 (HH1), and JK98. The phenotypes growth and survival rates of these populations were compared to confirm the feasibility for crossbreeding. The body length (BL), carapace length (CL), carapace width (CW), height of the second and third abdominal segment (HST), width of the second and third abdominal segment (WST), length of the first abdominal segment (LF), length of the last abdominal segment (LL), live body weight (BW), and survival rate were measured. Different combinations were statistically performed with ANOVA and Duncan’s Multiple Range Test. The results show that the survival rate of JK98(♀)×WKN(♂) was the highest, followed by WYP(♀)×WKN(♂), FKN(♀)×WYP(♂), FKN(♀)×HH1(♂) and WYP(♀)×FKN(♂); the body weight of FKN(♀)sxHH1(♂) was the highest, followed by FKN(♀)×WYP(♂), WYP(♀)×WKN(♂), WYP(♀)×FKN(♂) and JK98(♀)×WKN(♂); the total length had the same ranking as the body weight. All growth traits in hybrids JK98(♀)×WKN(♂) were the lowest among all combinations. F1 hybrids had significant difference (P0.05) in other growth traits and survival rate. The results of Duncan’s Multiple Range Test are that BL and CL of JK98(♀)×WKN(♂) were significantly different from the other combinations; HST different from the combination of FKN(♀)×WYP(♂), FKN(♀)×HH1(♂) and WYP

  19. Economic growth, income equality, and population health among the Asian Tigers.

    Science.gov (United States)

    Siddiqi, A; Hertzman, C

    2001-01-01

    The "Tiger" economies of Southeast Asia provide examples of developing nations where economic growth and increasing income equality are compatible and, when occurring together, are associated with superior health trends over time. The degree of income inequality in the Asian Tigers declined during the period of rapid economic growth. Traditionally, economists have viewed economic growth and relative parity in income distribution as incompatible, or trade-offs. This poses a public policy dilemma, since a reasonable propensity to increase a nation's overall economic well-being would mean forsaking measures that increase income parity. The Asian Tigers, however, have shown that this need not be viewed as a trade-off. Economic growth and a simultaneous increase in income equality are possible and, with respect to health outcomes, desirable. The authors propose a variety of mechanisms through which income inequality can enhance economic growth, and discuss policies in education, agricultural land reform, and housing that influence the simultaneous attainment of income equality and economic growth.

  20. Decades of Urban Growth and Development on Deltas; Comparative Global Analysis of Night Lights and Population

    Science.gov (United States)

    Small, C.; Elvidge, C.; Yetman, G.; Baugh, K.; MacManus, K.

    2016-12-01

    It is well-known that coastal zones in general, and deltas in particular, are among the most densely populated environments on Earth. Decades of satellite imagery offer spatially explicit observations of the changing land use and development of deltas worldwide. Stable night lights provide globally consistent proxies for lighted development associated with a variety of human settlement types. Gridded census enumerations provide geospatial depictions of human population density associated with residential population distributions. Recent improvements in both night light imaging and census data resolution allow us to compare stable night light and residential population density with much greater spatial correspondence than previously possible. We use night light brightness from the Visible/Infrared Imaging Radiometer Suite (VIIRS) on the NASA/NOAA Suomi satellite and population density grids from the NASA SEDAC Gridded Population of the World v.4 (GPWv4) product to derive density/intensity transfer functions for a wide range of urban/rural gradients worldwide. These transfer functions provide the basis for spatial disaggregation of population using the higher resolution night light imagery in areas where census data lack the resolution for meaningful analysis of population and coastal hazard. Disaggregated population maps are combined with digital elevation models to estimate current population distributions with elevation and fluvial proximity for several of the world's most densely populated deltas. In addition, we use DMSP-OLS night light composites to map changes in lighted development on these deltas since 1992. Landsat imagery is then used to map the land cover changes associated with increases in night light brightness on these deltas. The result allows for spatially explicit comparisons of development patterns in different types of deltaic environments. We present a generalized methodology for mapping development and land cover with sufficient detail and

  1. Effect of Component Population on the Growth and Yield of Maize ...

    African Journals Online (AJOL)

    Field experiment to determine the optimum component populations of maize (Zea mays L.) and egusi melon Colocynthis citrullus L. Schrad) component crops in intercrop were conducted in 2004 and 2005 cropping seasons. There were three maize populations (17,780; 26,670 and 53,330 plants/ha), three egusi melon ...

  2. Past, Present and Future: Immigration, High Fertility Fuel State's Population Growth.

    Science.gov (United States)

    Clark, William A. V.

    2000-01-01

    Presents demographic information on California's increasing population and ethnic diversity. Describes age pyramids and fertility rates by ethnic group, indicating that Asians and Hispanics will comprise over two-thirds of the state's population by 2030. Discusses implications for education, teenage pregnancy, political representation, prenatal…

  3. Population growth and the environment in Africa : local informal institutions, the missing link

    NARCIS (Netherlands)

    Mazzucato, V.; Niemeijer, D.

    2002-01-01

    Population and environment debates regarding Africa, whether Malthusian or Boserupian in nature, focus on population levels as the driving force behind the relationship between environment and society. This article argues, instead, that how people adjust to their rise in numbers is more important

  4. Effect of Plant Population and Nitrogen on Growth and Dry Matter ...

    African Journals Online (AJOL)

    Variety was in the main plots, with population and nitrogen in the sub–plots and sub–sub plots, respectively. The results showed that there was year x variety interaction effects on all the parameters studied. Average over the years, population and nitrogen, TZB produced 12% more leaves than TZESRW. However, TZESRW ...

  5. Does pollen limitation affect population growth of the endangered Dracocephalum austriacum L.?

    NARCIS (Netherlands)

    Castro, S.; Dostálek, T.; van der Meer, S.; Oostermeijer, G.; Münzbergová, Z.

    2015-01-01

    Reproductive strategies can have significant consequences for the viability of plant populations. Still, the effects of lower fruit set due to pollen limitation on plant demography and population persistence have rarely been explored. The objectives of this study were to assess the ecological

  6. Physical activity and health in the presence of China's economic growth: Meeting the public health challenges of the aging population

    Directory of Open Access Journals (Sweden)

    Fuzhong Li

    2016-09-01

    Full Text Available Three decades of rapid economic development in China have not only benefited millions of Chinese by improving their living standards but have also dramatically increased the number of people who are part of the country's aging population. However, economic growth has not been accompanied by sufficient attention given to important public health issues, including an increase in the incidence of chronic diseases and a decline in physical activity (PA that comes with an aging population. The rapid growth in China's older population will soon exert an impact on the nation's economy, population health status, and health behaviors, and will increase stress on its healthcare system. This review article provides a broad perspective on the impact of rapid economic development, industrialization, and urbanization on health-related behaviors, with a specific focus on PA among older adults. Specifically, the article offers an overview of the demographic context, significant public health challenges, evidence on PA and exercise interventions, and knowledge gaps and future directions for research.

  7. Impact of Rainfall, Land-Cover and Population Growth on Groundwater - A Case Study From Karnataka State, India

    Science.gov (United States)

    Srivastav, R. K.; Chinnapa Reddy, A. R.

    2015-12-01

    Recent trends in climate, land-use pattern and population has affected almost every portable water resources in the world. Due to depleting surface water and untimely distribution of precipitation, the demand to use groundwater has increased considerably. Further recent studies have shown that the groundwater stress is more in developing countries like India. This study focuses on understanding the impacts of three major factors (i.e., rainfall, land-cover and population growth) effecting the groundwater levels. For this purpose, the correlation between the trends in groundwater time series is compared with trends in rainfall, land-cover and population growth. To detect the trends in time series, two statistical methods namely, least square method and Mann-Kendall method, are adopted. The results were analyzed based on the measurements from 1800 observation wells in the Karnataka state, India. The data is obtained for a total of 9 year time period ranging from 2005 to 2013. A gridded precipitation data of 0.5o× 0.5o over the entire region is used. The change in land-cover and population data was approximately obtained from the local governing bodies. The early results show significant correlation between rainfall and groundwater time series trends. The outcomes will assess the vulnerability of groundwater levels under changing physical and hydroclimatic conditions, especially under climate change.

  8. Individual growth and reproductive behavior in a newly established population of northern snakehead (Channa argus), Potomac River, USA

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    Landis, Andrew M. Gascho; Lapointe, Nicolas W. R.; Angermeier, Paul L.

    2010-01-01

    Northern snakehead (Channa argus) were first found in the Potomac River in 2004. In 2007, we documented feeding and reproductive behavior to better understand how this species is performing in this novel environment. From April to October, we used electrofishing surveys to collect data on growth, condition, and gonad weight of adult fish. Growth rates of young were measured on a daily basis for several weeks. Mean length-at-age for Potomac River northern snakehead was lower than for fish from China, Russia, and Uzbekistan. Fish condition was above average during spring and fall, but below average in summer. Below-average condition corresponded to periods of high spawning activity. Gonadosomatic index indicated that females began spawning at the end of April and continued through August. Peak spawning occurred at the beginning of June when average temperatures reached 26°C. Larval fish growth rate, after the transition to exogenous feeding, was 2.3 (SD ± 0.7) mm (total length, TL) per day. Although Potomac River northern snakehead exhibited lower overall growth rates when compared to other populations, these fish demonstrated plasticity in timing of reproduction and rapid larval growth rates. Such life history characteristics likely contribute to the success of northern snakehead in its new environment and limit managers’ options for significant control of its invasion.

  9. Kinetic Behaviors of a Competitive Population and Fitness System in Exchange-Driven Growth

    Science.gov (United States)

    Lu, Ke; Lin, Zhen-Quan; Sun, Yun-Fei

    2008-07-01

    We proposed an aggregation model of two species aggregates of fitness and population to study the interaction between the two species in their exchange-driven processes of the same species by introducing the monomer birth of fitness catalyzed by the population, where the fitness aggregates perform self-death process and the population aggregates perform self-birth process. The kinetic behaviors of the aggregate size distributions of the fitness and population were analyzed by the rate equation approach with their exchange rate kernel K1(k,j) = K1kj and K2(k,j) = K2kj, the fitness aggregate's self-death rate kernel J1(k) = J1k, population aggregate's self-birth rate kernel J2(k) = J2k and population-catalyzed fitness birth rate kernel I(k,j) = Ikjv. The kinetic behavior of the fitness was found depending crucially on the parameter v, which reflects the dependence of the population-catalyzed fitness birth rate on the size of the catalyst (population) aggregate. (i) In the v birth of fitness is rather weak and the exchange-driven aggregation and self-death of the fitness dominate the process, and the fitness aggregate size distribution ak(t) does not have scale form. (ii) When v > 0, the effect of the population-catalyzed birth of fitness gets strong enough, and the catalyzed-birth and self-death of the fitness aggregates, together with the self-birth of the population aggregates dominate the evolution process of the fitness aggregates. The aggregate size distribution ak(t) approaches a generalized scaling form.

  10. Kinetic Behaviors of a Competitive Population and Fitness System in Exchange-Driven Growth

    International Nuclear Information System (INIS)

    Lu Ke; Lin Zhenquan; Sun Yunfei

    2008-01-01

    We proposed an aggregation model of two species aggregates of fitness and population to study the interaction between the two species in their exchange-driven processes of the same species by introducing the monomer birth of fitness catalyzed by the population, where the fitness aggregates perform self-death process and the population aggregates perform self-birth process. The kinetic behaviors of the aggregate size distributions of the fitness and population were analyzed by the rate equation approach with their exchange rate kernel K 1 (k,j) = K 1 kj and K 2 (k,j) = K 2 kj, the fitness aggregate's self-death rate kernel J 1 (k) = J 1 k, population aggregate's self-birth rate kernel J 2 (k) = J 2 k and population-catalyzed fitness birth rate kernel I(k,j) = Ikj v . The kinetic behavior of the fitness was found depending crucially on the parameter v, which reflects the dependence of the population-catalyzed fitness birth rate on the size of the catalyst (population) aggregate. (i) In the v ≤ 0 case, the effect of catalyzed-birth of fitness is rather weak and the exchange-driven aggregation and self-death of the fitness dominate the process, and the fitness aggregate size distribution a k (t) does not have scale form. (ii) When v > 0, the effect of the population-catalyzed birth of fitness gets strong enough, and the catalyzed-birth and self-death of the fitness aggregates, together with the self-birth of the population aggregates dominate the evolution process of the fitness aggregates. The aggregate size distribution a k (t) approaches a generalized scaling form

  11. Growth rate of invasive ductal carcinomas from a screened 50-74-year-old population.

    Science.gov (United States)

    Otten, Johannes Dm; van Schoor, Guido; Peer, Petronella Gm; den Heeten, Gerard J; Holland, Roland; Broeders, Mireille Jm; Verbeek, André Lm

    2018-03-01

    Objective As breast cancer growth rate is associated with menopause, most screening programmes target mainly women aged 50-74. We studied the association between age at diagnosis and growth rate in this screening-specific age range. Methods We used data from breast cancer patients diagnosed in the screening programme in Nijmegen, the Netherlands. The data were restricted to the screening rounds when analogue mammography was used in both the screening and clinical setting. Growth rate expressed as tumour volume doubling time was based on increasing tumour size in longitudinal series of mammograms. Estimates were based on (a) tumours showing at least two measurable shadows, (b) tumours showing a shadow at detection only (left censored), and (c) tumours showing no growth (right-censored observation). All 293 tumours were consecutively diagnosed invasive ductal breast cancers in participants of the Nijmegen screening programme in the period 2000-2007. Results Depending on the assumptions made on tumour margins and mammographic density, the relation of volume doubling time with age non-significantly varies from a decrease of 3.3% to an increase of 1.4% for each year increase in age at diagnosis (all P-values ≥ 0.18). Applying left censoring on indistinct tumours, the geometric mean volume doubling time was 191 days (95% confidence interval 158-230). Conclusion We found no significant change in growth rate with age in women diagnosed with invasive ductal breast cancer in the screening age range 50-74. This outcome does not support differential screening intervals by age based solely on breast cancer growth rate for this particular group.

  12. Identification of top-down forces regulating cotton aphid population growth in transgenic Bt cotton in central China.

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    Peng Han

    Full Text Available The cotton aphid Aphis gossypii Glover is the main aphid pest in cotton fields in the Yangtze River Valley Cotton-planting Zone (YRZ in central China. Various natural enemies may attack the cotton aphid in Bt cotton fields but no studies have identified potential specific top-down forces that could help manage this pest in the YRZ in China. In order to identify possibilities for managing the cotton aphid, we monitored cotton aphid population dynamics and identified the effect of natural enemies on cotton aphid population growth using various exclusion cages in transgenic Cry1Ac (Bt+CpTI (Cowpea trypsin inhibitor cotton field in 2011. The aphid population growth in the open field (control was significantly lower than those protected or restricted from exposure to natural enemies in the various exclusion cage types tested. The ladybird predator Propylaea japonica Thunberg represented 65% of Coccinellidae predators, and other predators consisted mainly of syrphids (2.1% and spiders (1.5%. The aphid parasitoids Aphidiines represented 76.7% of the total count of the natural enemy guild (mainly Lysiphlebia japonica Ashmead and Binodoxys indicus Subba Rao & Sharma. Our results showed that P. japonica can effectively delay the establishment and subsequent population growth of aphids during the cotton growing season. Aphidiines could also reduce aphid density although their impact may be shadowed by the presence of coccinellids in the open field (likely both owing to resource competition and intraguild predation. The implications of these results are discussed in a framework of the compatibility of transgenic crops and top-down forces exerted by natural enemy guild.

  13. Effects of chestnut tannins and coconut oil on growth performance, methane emission, ruminal fermentation, and microbial populations in sheep.

    Science.gov (United States)

    Liu, H; Vaddella, V; Zhou, D

    2011-12-01

    This study was conducted to evaluate the effects of chestnut tannins (CT) and coconut oil (CO) on growth performance, methane (CH₄) emission, ruminal fermentation, and microbial populations in sheep. A total of 48 Rideau Arcott sheep (average body weight 31.5±1.97 kg, 16 wk old) were randomly assigned into 6 treatment groups in a 3 × 2 factorial design, with CT and CO as the main effects (8 sheep per group). The treatments were control diet (CTR), 10 or 30 g of CT/kg of diet (CT10 and CT30), 25 g of CO/kg of concentrate (CO25), and 10 or 30 g of CT/kg of diet+25 g of CO/kg of concentrate (CT10CO25 and CT30CO25). After the feeding trial (60 d), all sheep were moved to respiratory chambers to measure CH₄ emission. After CH₄ emission measurements, all sheep were slaughtered to obtain rumen fluid samples. Results showed that the addition of CT, CO, and CT+CO had no significant effects on growth performance of sheep but reduced CH₄ emission. Addition of CT reduced the NH₃-N concentration in rumen fluid in CT30. Addition of CO decreased the concentration of total volatile fatty acids in rumen fluid. No significant differences were observed in pH and molar proportion of volatile fatty acids among treatments. Addition of CT, CO, and CT+CO significantly decreased methanogen and protozoa populations. Moreover, CO decreased counts of Fibrobacter succinogenes. No significant differences were observed in populations of fungi, Ruminococcus flavefaciens, or Ruminococcus albus among treatments. In conclusion, supplementation of CT and CO seemed to be a feasible means of decreasing emissions of CH₄ from sheep by reduction of methanogen and protozoa populations with no negative effect on growth performance. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  14. Stand structure and climate influence on the growth trends of a marginal forest population of Pinus nigra spp. nigra

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    Maurizio Marchi

    2015-12-01

    Full Text Available The Black pine of Villetta Barrea (Pinus nigra ssp. nigra var italica is a variety of the nigra subspecies. It is naturally distributed only in the Abruzzo Region, near the village of Villetta Barrea, with a rear-edge marginal population.  A dendrochronological sampling of the population was implemented with the aim of studying its stand structure and the most probable interactions between growth trends and climate. Mensurational data were used to characterize the stand and, furthermore, the general correlation function (CF and the moving correlation function (MCF, with a 30 years window, were used to assess the interrelation between the growth of the tree rings and the climate.The results indicated that the past forest management, mainly carried out with thinnings from below and selective cuttings, influenced the current structure of the forest (mean diameter but no differences in growth trends were detected within the population.The survey on Villetta Barrea Black pine showed a positive and statistically significant correlation between the ring-width and the average temperatures of the months of December (before the ring formation - t-1, February and March; but it also showed a negative correlation with the temperatures of July, September and October of the current year (t.Moreover, the analysis with moving correlation functions suggested that, in the last decades, the population has negatively reacted to very few climate factors and, in particular, to the changes in temperatures (both minimum and maximum temperatures. This is especially true for the shifts occurred in September, the year of the ring formation.

  15. Assessing the Impact of Population Growth, Climate Change, and Land Use Change on Water Resources in India

    Science.gov (United States)

    Singh, N.; Cherkauer, K. A.

    2014-12-01

    India is poised to become the most populous country in the world by 2019 and reach a population of over 2 billion by 2050 based on current growth rates. It is also a region which will be under severe socio-economic and environmental stress if mitigation efforts are not adapted. In the past 10 years the population of India has grown by an average rate of 17 million people per year. In addition to unprecedented population growth, rapid urbanization and industrialization are straining the overburdened environmental system. This rapid growth in population, urbanization and industrialized will result in increased demand for food, requiring expansion of agricultural resources. Since total agricultural land in India has been relatively constant over the past 10 years the demand for additional food has to be partly met by enhanced production on existing land. Arable land in India has declined by around 3% according to FAOSTAT while the total agricultural area under irrigation has increased by about 9% thus further straining its water resources. In addition projections for future climate indicate that India is one of the regions where water resources are expected to be negatively impacted. Total agriculture water withdrawal in India increased by approximately 18 % from 2000-2010 while the total per capita water withdrawal increased by over 9% from 2000-2010. Total freshwater withdrawal as percentage of renewable water resources was around 40% in 2010. In addition, recent mandates of biofuel policies in India are also expected to impact its water resources. The combined impact of these various factors on future water availability in India could be one of the most severe globally due its unprecedented increase in population, food production and industrialization. In this study we assess the impact of land use and climate change on water resources over southern India in the face of a growing population and interest in development of national biofuel supplies. We use

  16. Rapid growth and genetic diversity retention in an isolated reintroduced black bear population in the central appalachians

    Science.gov (United States)

    Murphy, Sean M.; Cox, John J.; Clark, Joseph D.; Augustine, Benjamin J.; Hast, John T.; Gibbs, Dan; Strunk, Michael; Dobey, Steven

    2015-01-01

    Animal reintroductions are important tools of wildlife management to restore species to their historical range, and they can also create unique opportunities to study population dynamics and genetics from founder events. We used non-invasive hair sampling in a systematic, closed-population capture-mark-recapture (CMR) study design at the Big South Fork (BSF) area in Kentucky during 2010 and Tennessee during 2012 to estimate the demographic and genetic characteristics of the black bear (Ursus americanus) population that resulted from a reintroduced founding population of 18 bears in 1998. We estimated 38 (95% CI: 31–66) and 190 (95% CI: 170–219) bears on the Kentucky and Tennessee study areas, respectively. Based on the Tennessee abundance estimate alone, the mean annual growth rate was 18.3% (95% CI: 17.4–19.5%) from 1998 to 2012. We also compared the genetic characteristics of bears sampled during 2010–2012 to bears in the population during 2000–2002, 2–4 years following reintroduction, and to the source population. We found that the level of genetic diversity since reintroduction as indicated by expected heterozygosity (HE) remained relatively constant (HE(source, 2004) = 0.763, HE(BSF, 2000–2002) = 0.729, HE(BSF, 2010–2012) = 0.712) and the effective number of breeders (NB) remained low but had increased since reintroduction in the absence of sufficient immigration (NB(BSF, 2000–2002) = 12, NB(BSF, 2010–2012)  = 35). This bear population appears to be genetically isolated, but contrary to our expectations, we did not find evidence of genetic diversity loss or other deleterious genetic effects typically observed from small founder groups. We attribute that to high initial genetic diversity in the founder group combined with overlapping generations and rapid population growth. Although the population remains relatively small, the reintroduction using a small founder group appears to be demographically and genetically

  17. Population growth and within-plant distribution of the striped mealybug Ferrisia virgata (Cockerell (Hemiptera, Pseudococcidae on cotton

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    Martin D. Oliveira

    2014-03-01

    Full Text Available Population growth and within-plant distribution of the striped mealybug Ferrisia virgata (Cockerell (Hemiptera, Pseudococcidae on cotton. The striped mealybug, Ferrisia virgata (Cockerell (Hemiptera, Pseudococcidae, is a widely distributed and polyphagous pest species, which naturally occurs on cotton plants in Brazil. This study evaluated the establishment and population growth as well as the within-plant distribution of F. virgata on four cotton cultivars: CNPA 7H (white fibers, BRS Verde, BRS Safira, and BRS Rubi (colored fibers. The experiment was conducted in a complete randomized design with four treatments (cultivars and 18 replications of each. Thus, cotton plants of each cultivar were infested with 100 newly hatched nymphs of F. virgata. The number of adult female mealybugs and the total number of mealybugs per plant were quantified, respectively, at 25 and 50 days after infestation. The developmental and pre-reproductive periods were also determined. Furthermore, we verified the distribution of F. virgata on the plant parts at 25 and 50 days after infestation. Ferrisia virgata showed similar growth of 412-fold in the four cotton cultivars studied. Also, the nymphs were spread on infested leaves; the secondgeneration nymphs were spread and established in all plant parts. Our results characterize F. virgata as having much potential as an important cotton pest in Brazil.

  18. Population densities of indigenous Acidobacteria change in the presence of plant growth promoting rhizobacteria (PGPR) in rhizosphere.

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    Kalam, Sadaf; Das, Subha Narayan; Basu, Anirban; Podile, Appa Rao

    2017-05-01

    Rhizosphere microbial community has diverse metabolic capabilities and plays a crucial role in maintaining plant health. Oligotrophic plant growth promoting rhizobacteria (PGPR), along with difficult-to-culture microbial fractions, might be involved synergistically in microbe-microbe and plant-microbe interactions in the rhizosphere. Among the difficult-to-culture microbial fractions, Acidobacteria constitutes the most dominant phylum thriving in rhizospheric soils. We selected effective PGPR for tomato and black gram and studied their effect on population densities of acidobacterial members. Three facultatively oligotrophic PGPR were identified through 16S rRNA gene sequencing as Sphingobacterium sp. (P3), Variovorax sp. (P4), and Roseomonas sp. (A2); the latter being a new report of PGPR. In presence of selected PGPR strains, the changes in population densities of Acidobacteria were monitored in metagenomic DNA extracted from bulk and rhizospheric soils of tomato and black gram using real time qPCR. A gradual increase in equivalent cell numbers of Acidobacteria members was observed over time along with a simultaneous increase in plant growth promotion by test PGPR. We report characterization of three effective PGPR strains and their effects on indigenous, underexplored difficult-to-culture phylum-Acidobacteria. We suggest that putative interactions between these two bacterial groups thriving in rhizospheric soils could be beneficial for plant growth. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Language Growth in Children with Heterogeneous Language Disorders: A Population Study

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    Norbury, Courtenay Frazier; Vamvakas, George; Gooch, Debbie; Baird, Gillian; Charman, Tony; Simonoff, Emily; Pickles, Andrew

    2017-01-01

    Background: Language development has been characterised by significant individual stability from school entry. However, the extent to which trajectories of language growth vary in children with language disorder as a function of co-occurring developmental challenges is a question of theoretical import, with implications for service provision.…

  20. Cancer Stem Cell Plasticity as Tumor Growth Promoter and Catalyst of Population Collapse

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    Jan Poleszczuk

    2016-01-01

    Full Text Available It is increasingly argued that cancer stem cells are not a cellular phenotype but rather a transient state that cells can acquire, either through intrinsic signaling cascades or in response to environmental cues. While cancer stem cell plasticity is generally associated with increased aggressiveness and treatment resistance, we set out to thoroughly investigate the impact of different rates of plasticity on early and late tumor growth dynamics and the response to therapy. We develop an agent-based model of cancer stem cell driven tumor growth, in which plasticity is defined as a spontaneous transition between stem and nonstem cancer cell states. Simulations of the model show that plasticity can substantially increase tumor growth rate and invasion. At high rates of plasticity, however, the cells get exhausted and the tumor will undergo spontaneous remission in the long term. In a series of in silico trials, we show that such remission can be facilitated through radiotherapy. The presented study suggests that s