[Fifty years of population growth and absorbing manual labor in Brazil, 1950-2000].

PubMed

Paiva, P D

1986-01-01

The economically active population has grown rapidly in Brazil, resulting either from population growth or increased female participation in the work force. This rhythm of growth will continue at least until the end of this century. The authors suggest that the impact of the recent decline in fertility will be moderate and will only affect the younger age groups. Despite the rapid growth of employment in the processing industry, the relative size of the so-called informal sector has remained stable since 1950. It is further predicted that, given the economically active population's rate of growth and the decrease in employment in agriculture, there will be a great demand for urban employment in the next 20 years.

The little women of Loja--growth hormone-receptor deficiency in an inbred population of southern Ecuador.

PubMed

Rosenbloom, A L; Guevara Aguirre, J; Rosenfeld, R G; Fielder, P J

1990-11-15

Laron-type dwarfism, which is characterized by the clinical appearance of isolated growth hormone deficiency with elevated serum levels of growth hormone and decreased serum levels of insulin-like growth factor I (IGF-I), has been described in approximately 50 patients. This condition is caused by a deficiency of the cellular receptor for growth hormone, and it is transmitted as an autosomal recessive trait, as indicated by an equal sex distribution and a high rate of consanguinity in affected families. We studied 20 patients (19 females and 1 male, 2 to 49 years of age), from an inbred Spanish population in southern Ecuador, who had the clinical features of Laron-type dwarfism. Seventeen patients were members of two large pedigrees. Among the 13 affected sibships, there were 19 affected and 24 unaffected female siblings and 1 affected and 21 unaffected male siblings. The patients' heights ranged from 10.0 to 6.7 SD below the normal mean height for age in the United States. In addition to the previously described features, 15 patients had limited elbow extensibility, all had blue scleras, affected adults had relatively short extremities, and all four affected women over 30 years of age had hip degeneration. Basal serum concentrations of growth hormone were elevated in all affected children (30 to 160 micrograms per liter) and normal to moderately elevated in the adults. The serum level of growth hormone-binding protein ranged from 1 to 30 percent of normal; IGF-I concentrations were low--less than or equal to 7 micrograms per liter in the children and less than or equal to 66 micrograms per liter in the adults (normal for Ecuadorean women, 98 to 238). Serum levels of IGF-II and growth hormone-dependent IGF-binding protein-3 were also low. We describe an inbred population with a high incidence of growth hormone-receptor deficiency resulting in a clinical picture resembling Laron-type dwarfism but differing principally in showing a marked predominance of affected

Human Population: Fundamentals of Growth and Change.

ERIC Educational Resources Information Center

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";…

Calculating second derivatives of population growth rates for ecology and evolution

PubMed Central

Shyu, Esther; Caswell, Hal

2014-01-01

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 R0, 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. PMID:25793101

Bird population trends are linearly affected by climate change along species thermal ranges.

PubMed

Jiguet, Frédéric; Devictor, Vincent; Ottvall, Richard; Van Turnhout, Chris; Van der Jeugd, Henk; Lindström, Ake

2010-12-07

Beyond the effects of temperature increase on local population trends and on species distribution shifts, how populations of a given species are affected by climate change along a species range is still unclear. We tested whether and how species responses to climate change are related to the populations locations within the species thermal range. We compared the average 20 year growth rates of 62 terrestrial breeding birds in three European countries along the latitudinal gradient of the species ranges. After controlling for factors already reported to affect bird population trends (habitat specialization, migration distance and body mass), we found that populations breeding close to the species thermal maximum have lower growth rates than those in other parts of the thermal range, while those breeding close to the species thermal minimum have higher growth rates. These results were maintained even after having controlled for the effect of latitude per se. Therefore, the results cannot solely be explained by latitudinal clines linked to the geographical structure in local spring warming. Indeed, we found that populations are not just responding to changes in temperature at the hottest and coolest parts of the species range, but that they show a linear graded response across their European thermal range. We thus provide insights into how populations respond to climate changes. We suggest that projections of future species distributions, and also management options and conservation assessments, cannot be based on the assumption of a uniform response to climate change across a species range or at range edges only.

Population Growth Types in India, 1961-71

ERIC Educational Resources Information Center

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)

Population priorities: the challenge of continued rapid population growth.

PubMed

Turner, Adair

2009-10-27

Rapid population growth continues in the least developed countries. The revisionist case that rapid population could be overcome by technology, that population density was advantageous, that capital shallowing is not a vital concern and that empirical investigations had not proved a correlation between high population growth and low per capita income was both empirically and theoretically flawed. In the modern world, population density does not play the role it did in nineteenth-century Europe and rates of growth in some of today's least developed nations are four times than those in nineteenth-century Europe, and without major accumulation of capital per capita, no major economy has or is likely to make the low- to middle-income transition. Though not sufficient, capital accumulation for growth is absolutely essential to economic growth. While there are good reasons for objecting to the enforced nature of the Chinese one-child policy, we should not underestimate the positive impact which that policy has almost certainly had and will have over the next several decades on Chinese economic performance. And a valid reticence about telling developing countries that they must contain fertility should not lead us to underestimate the severely adverse impact of high fertility rates on the economic performance and prospects of many countries in Africa and the Middle East.

Population Growth: Crisis and Challenge.

ERIC Educational Resources Information Center

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…

A new ODE tumor growth modeling based on tumor population dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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.

Canada's population: growth and dualism.

PubMed

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.

Teaching about Population Growth.

ERIC Educational Resources Information Center

Otero, George G., Jr., Comp.

This teaching guide contains 20 activities on population growth for students in grades 6-12. The purpose is to help students gain the skills, knowledge, and understanding of population dynamics so that they can make rational decisions and take responsible action regarding population matters and public policy. Activities are organized around the…

Population growth, agrarian peasant economy and environmental degradation in Tanzania.

PubMed

Madulu, N F

1995-03-01

Population strategies to relieve the density pressures on land and resources in Tanzania have not considered the basic causes of population growth. Resettlement results in the same environmental degradation as in the original settlement. There should be a reduction in the population growth and planning of proper land use and resource exploitation before resettlement. Rural development must include a decline in the dependency on subsistence agriculture. Population in Tanzania increased by 213% during 1948-88. An absolute increase in population size during 1978-88 is recorded despite a slight decline in the rate of growth. Death rates declined, but birth rates were relatively stable at around 50 per 1000 population. Regions with the highest growth rates were Dar es Salaam (4.8%), Rukwa (4.3%), Arusha (3.8%), Mbeya (3.1%), and Ruvuma (3.2%). The regions with the lowest rates were Tanga and Kilimanjaro (2.1%), Coast (2.1%), Lindi (2%), and Mtwara (1.4%). Low growth rates are attributed to low fertility and high infertility. Other factors affecting high growth rates are culture, rates of natural increase, intensity of internal and international migration, climatic conditions, and availability of resources. In 1988 46% of the population was under 15 years old. Per capita land availability declined from 11.8 hectares in 1948 to 3.8 hectares in 1988. The number of landless peasants increased. Productivity declined, and distances to farms increased. The total fertility rate was 6.5 children per woman in 1988 and 6.1 during 1991-92. Slight declines were apparent in the crude birth rate also. High fertility was a response to universal marriage, low contraceptive use (7% using modern methods during 1991-92), declining lactation periods, high mortality rates, and old traditions favoring large families. Children were used extensively in time-consuming and labor-intensive activities, such as fetching water. The mean number of children ever born was higher among women with 1

The relationship between population ageing and the economic growth in Asia

NASA Astrophysics Data System (ADS)

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.

Population growth, inequality and poverty.

PubMed

Rodgers, G

1983-01-01

In this discussion of population growth, inequality, and poverty, the type of relationships that can be observed in intercountry comparisons are explored, reviewing the findings of several other authors, presenting some new estimates using an International Labor Office data bank, considering some basic conceptual problems, and examining some of the theoretical and empirical issues that call for investigation at the national level. Intercountry comparisons, despite their limitations, appear to be the easiest starting point for empirical analysis. The approach adopted by most researchers has been to select 1 or more population indicators and a measure of national income inequality and to explain intercountry differences in 1 or both of these variables in terms of each other and of other indicators of economic and social development. Underlying this methodology is the assumption that there are aspects of demographic and economic change that are common to all countries included in the study, so that differences between countries give some guide to the likely evolution over time within any 1 country. This can be accepted at best with reservations, but given the scarcity of data on the evolution of inequality over time, a working hypothesis of this type appears unavoidable. But, as many of the factors likely to cause population growth and inequality operate over extended periods of time, a dynamic model is indicated. A simpler model, which pays particular attention to lags and variations over time, may generate new insights. A summary of the results of a new international cross-section analysis set up on these lines is presented. Results suggest that contrary to expectations, reducing population growth does not seem to generate longterm benefits for the poor in this model, though some short term gains are found. Increasing equality does appear to generate some decline in population growth, as well as persistent gains in incomes among the poor, but the reductions in

Population growth and development: the case of Bangladesh.

PubMed

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.

The containment of world population growth.

PubMed

Caldwell, J C

1975-12-01

The world has reached the present position of unprecedentedly rapid population growth not by achieving uniquely high fertility but by bringing about extraordinarily low mortality. The high growth rate and the built-in momentum of the age structure are obstacles to achievement of an acceptable standard of living for most of the world's population. Although government population programs have the potential to curb this growth rate, this potential has not been realized, and such programs are too often perceived both by their administrators and the population concerned as an end in themselves rather than a means toward a better standard of living. It is in this latter perspective, and in the context of the total development process, that population programs should be implemented.

Population growth rates: issues and an application.

PubMed Central

Godfray, H Charles J; Rees, Mark

2002-01-01

Current issues in population dynamics are discussed in the context of The Royal Society Discussion Meeting 'Population growth rate: determining factors and role in population regulation'. In particular, different views on the centrality of population growth rates to the study of population dynamics and the role of experiments and theory are explored. Major themes emerging include the role of modern statistical techniques in bringing together experimental and theoretical studies, the importance of long-term experimentation and the need for ecology to have model systems, and the value of population growth rate as a means of understanding and predicting population change. The last point is illustrated by the application of a recently introduced technique, integral projection modelling, to study the population growth rate of a monocarpic perennial plant, its elasticities to different life-history components and the evolution of an evolutionarily stable strategy size at flowering. PMID:12396521

Population growth and global security

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mumford, S.

A new threat to international and domestic security has emerged in the past three decades: uncontrolled world population growth. Current world population growth control efforts are ineffective. Unchecked growth will threaten global security by depleting food, energy, and other resources. Immigration is another complicating factor that is straining the carrying capacity of some overpopulated regions. Barriers to effective action include the desire of decision-makers to avoid the controversy of abortion and the role of the Catholic church in lobbying against birth control. (3 graphs, 12 photos, 2 tables)

Kinetic Model of Growth of Arthropoda Populations

NASA Astrophysics Data System (ADS)

Ershov, Yu. A.; Kuznetsov, M. A.

2018-05-01

Kinetic equations were derived for calculating the growth of crustacean populations ( Crustacea) based on the biological growth model suggested earlier using shrimp ( Caridea) populations as an example. The development cycle of successive stages for populations can be represented in the form of quasi-chemical equations. The kinetic equations that describe the development cycle of crustaceans allow quantitative prediction of the development of populations depending on conditions. In contrast to extrapolation-simulation models, in the developed kinetic model of biological growth the kinetic parameters are the experimental characteristics of population growth. Verification and parametric identification of the developed model on the basis of the experimental data showed agreement with experiment within the error of the measurement technique.

Metropolitan population growth in Arab countries.

PubMed

Vaidyanathan, K E

1977-01-01

A study or urban population growth in Arab countries has 3 objectives: 1) examination at the micro level of recent demographic trends in selected metropolitan areas of the Arab world and their relationship to changes in the total and urban populations in the respective countries; 2) estimation of net migration by sex and broad age groups for each metropolitan area; and 3) analysis of the pattern of variation in the metropolitan growth rates and their components, migration and natural increase. The study covers the cities proper or urban agglomerations, which includes the suburbs, whose population exceeded 100,000 in the most recent census. Altogether, the study covers 49 metropolitan areas from 9 Arab countries--Algeria; Morocco; Tunisia; Libya; Egypt; Sudan; Syria; Iraq; and Kuwait. Analysis revealed that metropolitan growth rates do follow geographic patterns. In countries with an oil-based economy, metropolitan growth rates are high; in countries with unexploited resources they are slightly below the 1st group; and countries which have pressure on land have low metropolitan growth rates. Population size of the metropolitan area appears to be an important factor associated with variations in metropolitan growth rates and net migration rates. Natural increase emerges as the predominant factor in metropolitan growth, but the differentials in the growth rates are more clearly associated with variations in net migration rates. As all the possibilities of analysis of relationships of metropolitan growth have not been exhausted, it is proposed to examine additional variables as possible factors associated with the speed of metropolitan growth.

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

PubMed

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.

Humic Fertilizer and Vermicompost Applied to the Soil Can Positively Affect Population Growth Parameters of Trichogramma brassicae (Hymenoptera: Trichogrammatidae) on Eggs of Tuta absoluta (Lepidoptera: Gelechiidae).

PubMed

Mohamadi, P; Razmjou, J; Naseri, B; Hassanpour, M

2017-12-01

The tomato leaf miner, Tuta absoluta (Meyrick), is a devastating pest of tomato worldwide. One of the control measures of T. absoluta is the use of biological control agents, such as Trichogramma wasps. Interactions between natural enemies and insect pests may be affected by application of fertilizers, because changes in plant quality through the fertilizer application may therefore affect herbivore characteristics and suitability of them to parasitism. Laboratory tests were carried out to evaluate the life table parameters of Trichogramma brassicae Bezdenko on T. absoluta eggs reared on tomato plants treated either with vermicompost (40%), humic fertilizer (2 g/kg soil), or control (suitable mixture of field soil and sand). Population growth parameters of T. brassicae were affected by fertilizer treatments. Significant differences were found for immature life period and total fecundity of T. brassicae on the treatments. Differences of intrinsic rate of natural increase (r m ), finite rate of increase (λ), net reproductive rate (R 0 ), mean generation time (T), and doubling time (DT) of T. brassicae among treatments were also significant. The lowest values of r m , λ, and R 0 were recorded for T. brassicae developed on T. absoluta eggs on control treatment, whereas the highest values of these parameters were observed on 2 g/kg humic fertilizer. Furthermore, T. brassicae had the shortest T and DT values on 2 g/kg humic fertilizer and 40% vermicompost treatments. Our results showed that application of humic fertilizer and vermicompost could positively affect population growth parameters of T. brassicae on eggs of T. absoluta fed on tomato plants.

Trans-generational influences of sulfamethoxazole on lifespan, reproduction and population growth of Caenorhabditis elegans.

PubMed

Yu, Zhenyang; Sun, Guohua; Liu, Yanjun; Yin, Daqiang; Zhang, Jing

2017-01-01

Trans-generational effects are increasingly used to indicate long-term influences of environmental pollutants. However, such studies can be complex and yield inconclusive results. In this study, the trans-generational effects of sulfamethoxazole (SMX) on Caenorhabditis elegans on lifespan, reproduction and population growth were tested for 7 consecutive generations, which included gestating generation (F0), embryo-exposed generation (F1), germline-exposed generation (F2), the first non-exposed generation (F3) and the three following generations (F4-F6). Results showed that lifespan was significantly affected by embryo exposure (F1) at 400µm SMX with a value as low as 47% of the control. The reproduction (a total brood size as 49% of the control) and population growth (81% of the control) were significantly affected in germline exposure (F2). Lifespan and reproduction were severely inhibited in non-exposed generations, confirming the real trans-generational effects. Notably, initial reproduction and reproduction duration showed opposite generation-related changes, indicating their interplay in the overall brood size. The population growth rate was well correlated with median lethal time, brood size and initial reproduction, which indicated that the population would increase when the nematodes lived longer and reproduced more offspring within shorter duration. Copyright © 2016 Elsevier Inc. All rights reserved.

Political economy of population growth.

PubMed

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.

Optimal population size and endogenous growth.

PubMed

Palivos, T; Yip, C K

1993-01-01

"Many applications in economics require the selection of an objective function which enables the comparison of allocations involving different population sizes. The two most commonly used criteria are the Benthamite and the Millian welfare functions, also known as classical and average utilitarianism, respectively. The former maximizes total utility of the society and thus represents individuals, while the latter maximizes average utility and so represents generations. Edgeworth (1925) was the first to conjecture, that the Benthamite principle leads to a larger population size and a lower standard of living.... The purpose of this paper is to examine Edgeworth's conjecture in an endogenous growth framework in which there are interactions between output and population growth rates. It is shown that, under conditions that ensure an optimum, the Benthamite criterion leads to smaller population and higher output growth rates than the Millian." excerpt

Modeling tradeoffs in avian life history traits and consequences for population growth

USGS Publications Warehouse

Clark, M.E.; Martin, T.E.

2007-01-01

Variation in population dynamics is inherently related to life history characteristics of species, which vary markedly even within phylogenetic groups such as passerine birds. We computed the finite rate of population change (??) from a matrix projection model and from mark-recapture observations for 23 bird species breeding in northern Arizona. We used sensitivity analyses and a simulation model to separate contributions of different life history traits to population growth rate. In particular we focused on contrasting effects of components of reproduction (nest success, clutch size, number of clutches, and juvenile survival) versus adult survival on ??. We explored how changes in nest success or adult survival coupled to costs in other life history parameters affected ?? over a life history gradient provided by our 23 Arizona species, as well as a broader sample of 121 North American passerine species. We further examined these effects for more than 200 passeriform and piciform populations breeding across North America. Model simulations indicate nest success and juvenile survival exert the largest effects on population growth in species with moderate to high reproductive output, whereas adult survival contributed more to population growth in long-lived species. Our simulations suggest that monitoring breeding success in populations across a broad geographic area provides an important index for identifying neotropical migratory populations at risk of serious population declines and a potential method for identifying large-scale mechanisms regulating population dynamics. ?? 2007 Elsevier B.V. All rights reserved.

The Population Growth and Carrying Capacity in Semarang City

NASA Astrophysics Data System (ADS)

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

Making a stand: five centuries of population growth in colonizing populations of Pinus ponderosa.

PubMed

Lesser, Mark R; Jackson, Stephen T

2012-05-01

The processes underlying the development of new populations are important for understanding how species colonize new territory and form viable long-term populations. Life-history-mediated processes such as Allee effects and dispersal capability may interact with climate variability and site-specific factors to govern population success and failure over extended time frames. We studied four disjunct populations of ponderosa pine in the Bighorn Basin of north-central Wyoming to examine population growth spanning more than five centuries. The study populations are separated from continuous ponderosa pine forest by distances ranging from 15 to >100 km. Strong evidence indicates that the initial colonizing individuals are still present, yielding a nearly complete record of population history. All trees in each population were aged using dendroecological techniques. The populations were all founded between 1530 and 1655 cal yr CE. All show logistic growth patterns, with initial exponential growth followed by a slowing during the mid to late 20th century. Initial population growth was slower than expectations from a logistic regression model at all four populations, but increased during the mid-18th century. Initial lags in population growth may have been due to strong Allee effects. A combination of overcoming Allee effects and a transition to favorable climate conditions may have facilitated a mid-18th century pulse in population growth rate.

Population growth and the decline of natural Southern yellow pine forests

Treesearch

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...

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

PubMed

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.

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

PubMed

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.

Does environmental policy affect scaling laws between population and pollution? Evidence from American metropolitan areas

PubMed Central

2017-01-01

Modern cities are engines of production, innovation, and growth. However, urbanization also increases both local and global pollution from household consumption and firms’ production. Do emissions change proportionately to city size or does pollution tend to outpace or lag urbanization? Do emissions scale differently with population versus economic growth or are emissions, population, and economic growth inextricably linked? How are the scaling relationships between emissions, population, and economic growth affected by environmental regulation? This paper examines the link between urbanization, economic growth and pollution using data from Metropolitan Statistical Areas (MSAs) in the United States between 1999 and 2011. We find that the emissions of local air pollution in these MSAs scale according to a ¾ power law with both population size and gross domestic product (GDP). However, the monetary damages from these local emissions scale linearly with both population and GDP. Counties that have previously been out of attainment with the local air quality standards set by the Clean Air Act show an entirely different relationship: local emissions scale according to the square root of population, while the monetary damages from local air pollution follow a 2/3rds power law with population. Counties out of attainment are subject to more stringent emission controls; we argue based on this that enforcement of the Clean Air Act induces sublinear scaling between emissions, damages, and city size. In contrast, we find that metropolitan GDP scales super-linearly with population in all MSAs regardless of attainment status. Summarizing, our findings suggest that environmental policy limits the adverse effects of urbanization without interfering with the productivity benefits that manifest in cities. PMID:28792949

Does environmental policy affect scaling laws between population and pollution? Evidence from American metropolitan areas.

PubMed

Muller, Nicholas Z; Jha, Akshaya

2017-01-01

Modern cities are engines of production, innovation, and growth. However, urbanization also increases both local and global pollution from household consumption and firms' production. Do emissions change proportionately to city size or does pollution tend to outpace or lag urbanization? Do emissions scale differently with population versus economic growth or are emissions, population, and economic growth inextricably linked? How are the scaling relationships between emissions, population, and economic growth affected by environmental regulation? This paper examines the link between urbanization, economic growth and pollution using data from Metropolitan Statistical Areas (MSAs) in the United States between 1999 and 2011. We find that the emissions of local air pollution in these MSAs scale according to a ¾ power law with both population size and gross domestic product (GDP). However, the monetary damages from these local emissions scale linearly with both population and GDP. Counties that have previously been out of attainment with the local air quality standards set by the Clean Air Act show an entirely different relationship: local emissions scale according to the square root of population, while the monetary damages from local air pollution follow a 2/3rds power law with population. Counties out of attainment are subject to more stringent emission controls; we argue based on this that enforcement of the Clean Air Act induces sublinear scaling between emissions, damages, and city size. In contrast, we find that metropolitan GDP scales super-linearly with population in all MSAs regardless of attainment status. Summarizing, our findings suggest that environmental policy limits the adverse effects of urbanization without interfering with the productivity benefits that manifest in cities.

Spatial variation in population growth rate and community structure affects local and regional dynamics.

PubMed

Trzcinski, M Kurtis; Walde, Sandra J; Taylor, Philip D

2008-11-01

1. Theory predicting that populations with high maximum rates of increase (r(max)) will be less stable, and that metapopulations with high average r(max) will be less synchronous, was tested using a small protist, Bodo, that inhabits pitcher plant leaves (Sarracenia purpurea L.). The effects of predators and resources on these relationships were also determined. 2. Abundance data collected for a total of 60 populations of Bodo, over a period of 3 months, at six sites in three bogs in eastern Canada, were used to test these predictions. Mosquitoes were manipulated in half the leaves partway through the season to increase the range of predation rates. 3. Dynamics differed greatly among leaves and sites, but most populations exhibited one or more episodes of rapid increase followed by a population crash. Estimates of r(max) obtained using a linear mixed-effects model, ranged from 1 x 5 to 2 x 7 per day. Resource levels (captured insect) and midge abundances affected r(max). 4. Higher r(max) was associated with greater temporal variability and lower synchrony as predicted. However, in contrast to expectations, populations with higher r(max) also had lower mean abundance and were more suppressed by predators. 5. This study demonstrates that the link between r(max) and temporal variability is key to understanding the dynamics of populations that spend little time near equilibrium, and to predicting and interpreting the effects of community structure on the dynamics of such populations.

U.S. Population Growth: Prospects and Policy.

ERIC Educational Resources Information Center

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)

Translating effects of inbreeding depression on component vital rates to overall population growth in endangered bighorn sheep.

PubMed

Johnson, Heather E; Mills, L Scott; Wehausen, John D; Stephenson, Thomas R; Luikart, Gordon

2011-12-01

Evidence of inbreeding depression is commonly detected from the fitness traits of animals, yet its effects on population growth rates of endangered species are rarely assessed. We examined whether inbreeding depression was affecting Sierra Nevada bighorn sheep (Ovis canadensis sierrae), a subspecies listed as endangered under the U.S. Endangered Species Act. Our objectives were to characterize genetic variation in this subspecies; test whether inbreeding depression affects bighorn sheep vital rates (adult survival and female fecundity); evaluate whether inbreeding depression may limit subspecies recovery; and examine the potential for genetic management to increase population growth rates. Genetic variation in 4 populations of Sierra Nevada bighorn sheep was among the lowest reported for any wild bighorn sheep population, and our results suggest that inbreeding depression has reduced adult female fecundity. Despite this population sizes and growth rates predicted from matrix-based projection models demonstrated that inbreeding depression would not substantially inhibit the recovery of Sierra Nevada bighorn sheep populations in the next approximately 8 bighorn sheep generations (48 years). Furthermore, simulations of genetic rescue within the subspecies did not suggest that such activities would appreciably increase population sizes or growth rates during the period we modeled (10 bighorn sheep generations, 60 years). Only simulations that augmented the Mono Basin population with genetic variation from other subspecies, which is not currently a management option, predicted significant increases in population size. Although we recommend that recovery activities should minimize future losses of genetic variation, genetic effects within these endangered populations-either negative (inbreeding depression) or positive (within subspecies genetic rescue)-appear unlikely to dramatically compromise or stimulate short-term conservation efforts. The distinction between

EFFECT OF FLUID SHEAR AND IRRADIANCE ON POPULATION GROWTH AND CELLULAR TOXIN CONTENT OF THE DINOFLAGELLATE ALEXANDRIUM FUNDYENSE.

EPA Science Inventory

The potential for in situ turbulence to inhibit dinoflagellate population growth has been demonstrated by experimentally exposing dinoflagellate cultures to quantified shear flow. However, despite interest in understanding environmental factors that affect the growth of toxic din...

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

PubMed Central

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

2017-01-01

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. PMID:29087298

Hispanic Population Growth and Rural Income Inequality

ERIC Educational Resources Information Center

Parrado, Emilio A.; Kandel, William A.

2010-01-01

We analyze the relationship between Hispanic population growth and changes in U.S. rural income inequality from 1990 through 2000. Applying comparative approaches used for urban areas we disentangle Hispanic population growth's contribution to inequality by comparing and statistically modeling changes in the family income Gini coefficient across…

Population Growth and Economic and Social Development.

ERIC Educational Resources Information Center

Clausen, A. W.

Because evidence is clear that in many developing countries development will be postponed indefinitely unless slower population growth can be achieved soon, the international community must work together in a renewed effort to slow population growth. Assistance can be accomplished in three ways: (1) encouraging dialog aimed at forging…

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

PubMed

DeLong, John P; Burger, Oskar; Hamilton, Marcus J

2010-10-05

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.

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

ERIC Educational Resources Information Center

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…

Meeting the Sustainable Development Goals leads to lower world population growth

PubMed Central

Abel, Guy J.; Barakat, Bilal; KC, Samir; Lutz, Wolfgang

2016-01-01

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. PMID:27911797

Population Growth and Poverty in the Developing World.

ERIC Educational Resources Information Center

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…

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

PubMed

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.

Population

EPA Science Inventory

Population growth influences many stressors on Narragansett Bay and its Watershed, including all landscape and chemical stressors discussed in other chapters of this report. In numerous ways, population growth affects the condition of the Bay ecosystem, Watershed ecosystem, and h...

Genetic variation facilitates seedling establishment but not population growth rate of a perennial invader

PubMed Central

Li, Shou-Li; Vasemägi, Anti; Ramula, Satu

2016-01-01

variation may facilitate plant invasions by increasing seedling establishment, it may not necessarily affect the long-term population growth rate. Therefore, established invasions may be able to grow equally well regardless of their genetic diversity. PMID:26420202

Metropolitan migration and population growth in selected developing countries.

PubMed

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

A review on the factors affecting mite growth in stored grain commodities.

PubMed

Collins, D A

2012-03-01

A thorough review of the literature has identified the key factors and interactions that affect the growth of mite pests on stored grain commodities. Although many factors influence mite growth, the change and combinations of the physical conditions (temperature, relative humidity and/or moisture content) during the storage period are likely to have the greatest impact, with biological factors (e.g. predators and commodity) playing an important role. There is limited information on the effects of climate change, light, species interactions, local density dependant factors, spread of mycotoxins and action thresholds for mites. A greater understanding of these factors may identify alternative control techniques. The ability to predict mite population dynamics over a range of environmental conditions, both physical and biological, is essential in providing an early warning of mite infestations, advising when appropriate control measures are required and for evaluating control measures. This information may provide a useful aid in predicting and preventing mite population development as part of a risk based decision support system.

Population growth and sustainable development in China.

PubMed

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.

Population growth of Varroa destructor (Acari: Varroidae) in honey bee colonies is affected by the number of foragers with mites

USDA-ARS?s Scientific Manuscript database

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 colonie...

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

PubMed

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.

Shanghai: a study on the spatial growth of population and economy in a Chinese metropolitan area.

PubMed

Zhu, J

1995-01-01

In this study of the growth in population and industry in Shanghai, China, between the 1982 and 1990 censuses, data on administrative divisions was normalized through digitization and spatial analysis. Analysis focused on spatial units, intensity of growth, time period, distance, rate of growth, and direction of spatial growth. The trisection method divided the city into city proper, outskirts, and suburbs. The distance function method considered the distance from center city as a function: exponential, power, trigonometric, logarithmic, and polynomial. Population growth and employment in all sectors increased in the outskirts and suburbs and decreased in the city proper except tertiary sectors. Primary sector employment decreased in all three sections. Employment in the secondary increased faster in the outskirts and suburbs than the total rate of growth of population and employment. In the city secondary sector employment rates decreased faster than total population and employment rates. The tertiary sector had the highest rate of growth in all sections, and employment grew faster than secondary sector rates. Tertiary growth was highest in real estate, finance, and insurance. Industrial growth in the secondary sector was 160.2% in the suburbs, 156.6% in the outskirts, and 80.9% in the city. In the distance function analysis, industry expanded further out than the entire secondary sector. Commerce grew the fastest in areas 15.4 km from center city. Economic growth was faster after economic reforms in 1978. Growth was led by industry and followed by the secondary sector, the tertiary sector, and population. Industrial expansion resulted from inner pressure, political factors controlling size, the social and economic system, and the housing construction and distribution system. Initially sociopsychological factors affected urban concentration.

Volatility and Growth in Populations of Rural Associations

ERIC Educational Resources Information Center

Wollebaek, Dag

2010-01-01

This article uses unique community-level data aggregated from censuses of associations to analyze growth and volatility in rural populations of grassroots associations. A qualitative comparative analysis (QCA) shows that the two main paths to growth were (1) centralization in polycephalous (multicentered) municipalities and (2) population growth…

Fertility decline and population growth: China's dilemma.

PubMed

Gu, B

1996-02-01

This article includes the assertion by the deputy director and demographer of the China Information and Research Center that China must maintain and implement a strict population policy in order to feed its large population. China has 22% of the world's total population but only 7% of the world's total cultivated land. The population rate varies by province and region in China and ranges from replacement level fertility in Shanghai to high growth in remote and underdeveloped provinces. About 70 million people live under the poverty line or have an annual family income of under 500 yuan. The family planning programs should emphasize a service oriented approach. The increased power of women and improved educational status of women are also desired. Concern is recognized in government circles about the rapid aging of the population. Rural-urban migration has improved the economic climate in cities, but migration has also resulted in "some serious social problems." China has a low fertility level but rapid population growth. In the 1990s about 21 million babies were born, which is a net increase of about 14 million annually. Population growth is serious because of a strong population momentum from the previous baby boom of the 1960s. China has accomplished a great deal in a short period of time in reducing fertility under unfavorable socioeconomic conditions. Credit must be given to the Chinese government, its various departments, and public response. Present population is over 1.2 billion, which is higher than the total population of developed countries of the world.

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

PubMed

Tkachenko, Natalie; Weissmann, John D; Petersen, Wesley P; Lake, George; Zollikofer, Christoph P E; Callegari, Simone

2017-01-01

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.

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

PubMed

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 (<100 per serving). Moreover, the exposure estimates obtained with the 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.

Can the Site-Frequency Spectrum Distinguish Exponential Population Growth from Multiple-Merger Coalescents?

PubMed Central

Eldon, Bjarki; Birkner, Matthias; Blath, Jochen; Freund, Fabian

2015-01-01

The ability of the site-frequency spectrum (SFS) to reflect the particularities of gene genealogies exhibiting multiple mergers of ancestral lines as opposed to those obtained in the presence of population growth is our focus. An excess of singletons is a well-known characteristic of both population growth and multiple mergers. Other aspects of the SFS, in particular, the weight of the right tail, are, however, affected in specific ways by the two model classes. Using an approximate likelihood method and minimum-distance statistics, our estimates of statistical power indicate that exponential and algebraic growth can indeed be distinguished from multiple-merger coalescents, even for moderate sample sizes, if the number of segregating sites is high enough. A normalized version of the SFS (nSFS) is also used as a summary statistic in an approximate Bayesian computation (ABC) approach. The results give further positive evidence as to the general eligibility of the SFS to distinguish between the different histories. PMID:25575536

Rapid Population Growth-Cause or Result of Global Problems?

ERIC Educational Resources Information Center

Schwartz, Richard H.

Explosive population growth is a symptom of the world's unjust and inequitable social, political, and economic conditions. The current rate of growth is staggering, particularly in the cities of the underdeveloped countries. While some progress has been made in slowing population growth, several factors still contribute to its momentum. One of…

Economic analyses of rapid population growth.

PubMed

Birdsall, N

1989-01-01

"Discussion of the macroeconomic consequences of rapid population growth is organized into three schools: pessimists, optimists, and the recent revisionists. For the revisionists, differing views are presented about the pervasiveness and relevance of market failures, such as the negative externalities of childbearing, and about the ability of families and institutions to adjust rapidly to changes brought on by rapid population growth. A welfare economics approach is used to review the merits of various public policies to reduce fertility, including public financing of family planning services and taxes and incentives associated with childbearing." The focus is on developing countries. excerpt

Genetic variation facilitates seedling establishment but not population growth rate of a perennial invader.

PubMed

Li, Shou-Li; Vasemägi, Anti; Ramula, Satu

2016-01-01

increasing seedling establishment, it may not necessarily affect the long-term population growth rate. Therefore, established invasions may be able to grow equally well regardless of their genetic diversity. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

THE IMPACT OF HISPANIC POPULATION GROWTH ON THE OUTLOOK OF AFRICAN AMERICANS

PubMed Central

Taylor, Marylee C.; Schroeder, Matthew B.

2014-01-01

We know too little about the effects of immigration on black Americans. If prior research yields mixed evidence about immigration’s consequences for the objective well-being of African Americans, it is silent about effects of immigration on blacks’ subjective well-being. To fill that void, this paper assesses the impact of the expanding Hispanic population on black Americans from a social psychological perspective. We ask whether blacks’ self-reported distress, social distrust, or attitudes toward Hispanics and immigrants are affected by the size of the local Hispanic population or by the percentage growth in local Hispanic residents. Answers come from responses of non-Hispanic black participants in the 1998–2002 General Social Surveys, linked to 1990 and 2000 census data. Contrary to pessimistic claims, most social psychological outcomes, including measures of economic distress, manifest no impact of local Hispanic numbers. The four exceptions, significant effects of local Hispanic population share or percentage growth evenly split in valence, underscore the complexity of recent immigration’s effects on African Americans. PMID:25242830

Understanding the demographic drivers of realized population growth rates.

PubMed

Koons, David N; Arnold, Todd W; Schaub, Michael

2017-10-01

Identifying the demographic parameters (e.g., reproduction, survival, dispersal) that most influence population dynamics can increase conservation effectiveness and enhance ecological understanding. Life table response experiments (LTRE) aim to decompose the effects of change in parameters on past demographic outcomes (e.g., population growth rates). But the vast majority of LTREs and other retrospective population analyses have focused on decomposing asymptotic population growth rates, which do not account for the dynamic interplay between population structure and vital rates that shape realized population growth rates (λt=Nt+1/Nt) in time-varying environments. We provide an empirical means to overcome these shortcomings by merging recently developed "transient life-table response experiments" with integrated population models (IPMs). IPMs allow for the estimation of latent population structure and other demographic parameters that are required for transient LTRE analysis, and Bayesian versions additionally allow for complete error propagation from the estimation of demographic parameters to derivations of realized population growth rates and perturbation analyses of growth rates. By integrating available monitoring data for Lesser Scaup over 60 yr, and conducting transient LTREs on IPM estimates, we found that the contribution of juvenile female survival to long-term variation in realized population growth rates was 1.6 and 3.7 times larger than that of adult female survival and fecundity, respectively. But a persistent long-term decline in fecundity explained 92% of the decline in abundance between 1983 and 2006. In contrast, an improvement in adult female survival drove the modest recovery in Lesser Scaup abundance since 2006, indicating that the most important demographic drivers of Lesser Scaup population dynamics are temporally dynamic. In addition to resolving uncertainty about Lesser Scaup population dynamics, the merger of IPMs with transient LTREs will

Explosive genetic evidence for explosive human population growth

PubMed Central

Gao, Feng; Keinan, Alon

2016-01-01

The advent of next-generation sequencing technology has allowed the collection of vast amounts of genetic variation data. A recurring discovery from studying larger and larger samples of individuals had been the extreme, previously unexpected, excess of very rare genetic variants, which has been shown to be mostly due to the recent explosive growth of human populations. Here, we review recent literature that inferred recent changes in population size in different human populations and with different methodologies, with many pointing to recent explosive growth, especially in European populations for which more data has been available. We also review the state-of-the-art methods and software for the inference of historical population size changes that lead to these discoveries. Finally, we discuss the implications of recent population growth on personalized genomics, on purifying selection in the non-equilibrium state it entails and, as a consequence, on the genetic architecture underlying complex disease and the performance of mapping methods in discovering rare variants that contribute to complex disease risk. PMID:27710906

Agriculture, population growth, and statistical analysis of the radiocarbon record.

PubMed

Zahid, H Jabran; Robinson, Erick; Kelly, Robert L

2016-01-26

The human population has grown significantly since the onset of the Holocene about 12,000 y ago. Despite decades of research, the factors determining prehistoric population growth remain uncertain. Here, we examine measurements of the rate of growth of the prehistoric human population based on statistical analysis of the radiocarbon record. We find that, during most of the Holocene, human populations worldwide grew at a long-term annual rate of 0.04%. Statistical analysis of the radiocarbon record shows that transitioning farming societies experienced the same rate of growth as contemporaneous foraging societies. The same rate of growth measured for populations dwelling in a range of environments and practicing a variety of subsistence strategies suggests that the global climate and/or endogenous biological factors, not adaptability to local environment or subsistence practices, regulated the long-term growth of the human population during most of the Holocene. Our results demonstrate that statistical analyses of large ensembles of radiocarbon dates are robust and valuable for quantitatively investigating the demography of prehistoric human populations worldwide.

Lebensraum: paradoxically, population growth may eventually end wars.

PubMed

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.

An evaluation of density-dependent and density-independent influences on population growth rates in Weddell seals

USGS Publications Warehouse

Rotella, J.J.; Link, W.A.; Nichols, J.D.; Hadley, G.L.; Garrott, R.A.; Proffitt, K.M.

2009-01-01

Much of the existing literature that evaluates the roles of density-dependent and density-independent factors on population dynamics has been called into question in recent years because measurement errors were not properly dealt with in analyses. Using state-space models to account for measurement errors, we evaluated a set of competing models for a 22-year time series of mark-resight estimates of abundance for a breeding population of female Weddell seals (Leptonychotes weddellii) studied in Erebus Bay, Antarctica. We tested for evidence of direct density dependence in growth rates and evaluated whether equilibrium population size was related to seasonal sea-ice extent and the Southern Oscillation Index (SOI). We found strong evidence of negative density dependence in annual growth rates for a population whose estimated size ranged from 438 to 623 females during the study. Based on Bayes factors, a density-dependence-only model was favored over models that also included en! vironmental covariates. According to the favored model, the population had a stationary distribution with a mean of 497 females (SD = 60.5), an expected growth rate of 1.10 (95% credible interval 1.08-1.15) when population size was 441 females, and a rate of 0.90 (95% credible interval 0.87-0.93) for a population of 553 females. A model including effects of SOI did receive some support and indicated a positive relationship between SOI and population size. However, effects of SOI were not large, and including the effect did not greatly reduce our estimate of process variation. We speculate that direct density dependence occurred because rates of adult survival, breeding, and temporary emigration were affected by limitations on per capita food resources and space for parturition and pup-rearing. To improve understanding of the relative roles of various demographic components and their associated vital rates to population growth rate, mark-recapture methods can be applied that incorporate both

The outlook for population growth.

PubMed

Lee, Ronald

2011-07-29

Projections of population size, growth rates, and age distribution, although extending to distant horizons, shape policies today for the economy, environment, and government programs such as public pensions and health care. The projections can lead to costly policy adjustments, which in turn can cause political and economic turmoil. The United Nations projects global population to grow from about 7 billion today to 9.3 billion in 2050 and 10.1 billion in 2100, while the Old Age Dependency Ratio doubles by 2050 and triples by 2100. How are such population projections made, and how certain can we be about the trends they foresee?

Response to long-term growth hormone therapy in patients affected by RASopathies and growth hormone deficiency: Patterns of growth, puberty and final height data.

PubMed

Tamburrino, Federica; Gibertoni, Dino; Rossi, Cesare; Scarano, Emanuela; Perri, Annamaria; Montanari, Francesca; Fantini, Maria Pia; Pession, Andrea; Tartaglia, Marco; Mazzanti, Laura

2015-11-01

RASopathies are developmental disorders caused by heterozygous germline mutations in genes encoding proteins in the RAS-MAPK signaling pathway. Reduced growth is a common feature. Several studies generated data on growth, final height (FH), and height velocity (HV) after growth hormone (GH) treatment in patients with these disorders, particularly in Noonan syndrome, the most common RASopathy. These studies, however, refer to heterogeneous cohorts in terms of molecular information, GH status, age at start and length of therapy, and GH dosage. This work reports growth data in 88 patients affected by RASopathies with molecularly confirmed diagnosis, together with statistics on body proportions, pubertal pattern, and FH in 33, including 16 treated with GH therapy for proven GH deficiency. Thirty-three patients showed GH deficiency after pharmacological tests, and were GH-treated for an average period of 6.8 ± 4.8 years. Before starting therapy, HV was -2.6 ± 1.3 SDS, and mean basal IGF1 levels were -2.0 ± 1.1 SDS. Long-term GH therapy, starting early during childhood, resulted in a positive height response compared with untreated patients (1.3 SDS in terms of height-gain), normalizing FH for Ranke standards but not for general population and Target Height. Pubertal timing negatively affected pubertal growth spurt and FH, with IGF1 standardized score increased from -2.43 to -0.27 SDS. During GH treatment, no significant change in bone age velocity, body proportions, or cardiovascular function was observed. © 2015 Wiley Periodicals, Inc.

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

PubMed

Zimmermann, Fabian; Ricard, Daniel; Heino, Mikko

2018-05-01

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

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

PubMed

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.

Nutrition, Development, and Population Growth

ERIC Educational Resources Information Center

Berg, Alan

1973-01-01

Focuses on the problem of malnutrition in developing countries through a description of its interrelationships with human development, national economies, economic growth and income, agricultural advances, the crisis in infant feeding practices, new foods, and the population dilemma. Outlines possible future policy directions to significantly…

[The fear of numbers or the challenge of population growth?].

PubMed

Loriaux, M

1991-12-01

Africa, currently one of the least densely populated continents, is growing so rapidly that its population will comprise some 1.5 billion inhabitants around 2020, and Africans will be more numerous than the population of the developed world. Attitudes about Africa's population size vary widely; many educated Africans believe that low density is a greater disadvantage than overpopulation, but most specialists believe the population of the developing world, and of Africa especially, to be too large, the prospects of significant voluntary reduction are dim. The rate of population growth has thus attracted attention as a factor amenable to modification. Africa's demographic transition remains largely in the future. Its case is unique because of the rate of demographic growth and because the phase of rapid growth will apparently continue far longer in Africa than in any other continent. The widening gap between population growth rates and rates of economic development in Africa inspires great pessimism about the future wellbeing of the population. Population officials urge that demographic growth be slowed in order to reduce pressure on economic and ecological resources and to gain time for social and economic development. But despite the consensus of international organizations, such as the UN Fund for Population, on the desirability of slowing population growth to encourage and permit economic growth, there has actually been relatively little progress since the time of Malthus in understanding the relationship between population, development, and the environment. Some recent works suggest that demographic growth has benefits as well as disadvantages, and the net impact on development is uncertain. Demographic pressure is in this view a far more potent force for innovation than is usually recognized. Population is not just an exogenous variable in development, but it is at the heart of the process. There can be no true integration of population into development until

Socioeconomic factors affecting marriage, divorce and birth rates in a Japanese population.

PubMed

Uchida, E; Araki, S; Murata, K

1993-10-01

The effects of low income, urbanisation and young age population on age-adjusted rates of first marriage, divorce and live birth among the Japanese population in 46 prefectures were analysed by stepwise regression for 1970 and for 1975. During this period, Japanese society experienced a drastic change from long-lasting economic growth to serious recession in 1973. In both 1970 and 1975, the first marriage rate for females was inversely related to low income and the divorce rates for both males and females were positively related to low income. The live birth rate was significantly related to low income, urbanisation and young age population only in 1975. The first marriage rate for females and the divorce rates for both sexes increased significantly but the first marriage rate for males and live birth rate significantly decreased between 1970 and 1975. These findings suggest that low income was the essential factor affecting first marriage for females and divorce for males and females.

[Population growth and the environment].

PubMed

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

Population Growth: Family Planning Programs.

ERIC Educational Resources Information Center

Doberenz, Alexander R., Ed.; Taylor, N. Burwell G., Ed.

These proceedings of the second annual symposium on population growth bring together speeches and panel discussions on family planning programs. Titles of speeches delivered are: Communicating Family Planning (Mrs. Jean Hutchinson); Effects of New York's Abortion Law Change (Dr. Walter Rogers); The Law and Birth Control, Sterilization and Abortion…

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

PubMed

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.

Anomalous Growth of Aging Populations

NASA Astrophysics Data System (ADS)

Grebenkov, Denis S.

2016-04-01

We consider a discrete-time population dynamics with age-dependent structure. At every time step, one of the alive individuals from the population is chosen randomly and removed with probability q_k depending on its age, whereas a new individual of age 1 is born with probability r. The model can also describe a single queue in which the service order is random while the service efficiency depends on a customer's "age" in the queue. We propose a mean field approximation to investigate the long-time asymptotic behavior of the mean population size. The age dependence is shown to lead to anomalous power-law growth of the population at the critical regime. The scaling exponent is determined by the asymptotic behavior of the probabilities q_k at large k. The mean field approximation is validated by Monte Carlo simulations.

Land use change and population growth in the Morobe Province of Papua New Guinea between 1975 and 2000.

PubMed

Ningal, Tine; Hartemink, A E; Bregt, A K

2008-04-01

The relation between human population growth and land use change is much debated. Here we present a case study from Papua New Guinea where the population has increased from 2.3 million in 1975 to 5.2 million in 2000. Since 85% of the population relies on subsistence agriculture, population growth affects agricultural land use. We assessed land use change in the Morobe province (33,933 km2) using topographic maps of 1975 and Landsat TM images of 1990 and 2000. Between 1975 and 2000, agricultural land use increased by 58% and population grew by 99%. Most new agricultural land was taken from primary forest and the forest area decreased from 9.8 ha person(-1) in 1975 to 4.4 ha person(-1) in 2000. Total population change and total land use change were strongly correlated. Most of the agricultural land use change occurred on Inceptisols in areas with high rainfall (>2500 mm year(-1)) on moderate to very steep slopes (10-56%). Agricultural land use changes in logged-over areas were in the vicinity of populated places (villages), and in close proximity to road access. There was considerable variation between the districts but districts with higher population growth also had larger increases in agricultural areas. It is concluded that in the absence of improved farming systems the current trend of increased agriculture with rapid population growth is likely to continue.

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

PubMed

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

Modeling Population Growth and Extinction

ERIC Educational Resources Information Center

Gordon, Sheldon P.

2009-01-01

The exponential growth model and the logistic model typically introduced in the mathematics curriculum presume that a population grows exclusively. In reality, species can also die out and more sophisticated models that take the possibility of extinction into account are needed. In this article, two extensions of the logistic model are considered,…

TOPICAL PROBLEMS: The phenomenological theory of world population growth

NASA Astrophysics Data System (ADS)

Kapitza, Sergei P.

1996-01-01

Of all global problems world population growth is the most significant. Demographic data describe this process in a concise and quantitative way in its past and present. Analysing this development it is possible by applying the concepts of systems analysis and synergetics, to work out a mathematical model for a phenomenological description of the global demographic process and to project its trends into the future. Assuming self-similarity as the dynamic principle of development, growth can be described practically over the whole of human history, assuming the growth rate to be proportional to the square of the number of people. The large parameter of the theory and the effective size of a coherent population group is of the order of 105 and the microscopic parameter of the phenomenology is the human lifespan. The demographic transition — a transition to a stabilised world population of some 14 billion in a foreseeable future — is a systemic singularity and is determined by the inherent pattern of growth of an open system, rather than by the lack of resources. The development of a quantitative nonlinear theory of the world population is of interest for interdisciplinary research in anthropology and demography, history and sociology, for population genetics and epidemiology, for studies in evolution of humankind and the origin of man. The model also provides insight into the stability of growth and the present predicament of humankind, and provides a setting for discussing the main global problems.

[World population growth and the food supply].

PubMed

Huang, Y

1982-07-29

The general trend in the last several hundred years has been that the speed of growth in the food supply exceeds the speed of the population growth. For the time being, 2 major problems still exist. The 1st problem is that food production is still influenced by natural conditions. For example, abnormal weather conditions may cause regional food shortages. The 2nd problem is the imbalance of food consumption by the world population. This phenomenon exists between different social classes as well as between developed and developing countries. According to statistics released by the World Bank, 1 billion suffer from malnutrition today and most of them are in developing countries. In developed countries, about half of their increase in the food supply is for feed grains, and those countries follow the policy of reducing farm land for the purpose of maintaing stabl e grain prices. Up to the present time, grain prices have been unstable, and this has become a rather heavy economic burden for numerous developing countries. Many developing countries are trying to increase grain production by increasing their arable land and promoting their cultivating techniques. However, these countries are facing the problems of finding and adequate water supply, fertilizer, and pesticides. In addition, a rapid population growth in these countries has offset their endeavors in agriculture. In recent years, these counties have realized the necessity of birth control. The world population growth rate has decreased from 2% to about 1.7% in 1981. Birth control and an increase in the food supply will bring new hope to the world's problems of overpopulation and food supply.

Different culture conditions affect the growth of human tendon stem/progenitor cells (TSPCs) within a mixed tendon cells (TCs) population.

PubMed

Viganò, M; Perucca Orfei, C; Colombini, A; Stanco, D; Randelli, P; Sansone, V; de Girolamo, L

2017-12-01

Tendon resident cells (TCs) are a mixed population made of terminally differentiated tenocytes and tendon stem/progenitor cells (TSPCs). Since the enrichment of progenitors proportion could enhance the effectiveness of treatments based on these cell populations, the interest on the effect of culture conditions on the TSPCs is growing. In this study the clonal selection and the culture in presence or absence of basic fibroblast growth factor (bFGF) were used to assess their influences on the stemness properties and phenotype specific features of tendon cells. Cells cultured with the different methods were analyzed in terms of clonogenic and differentiation abilities, stem and tendon specific genes expression and immunophenotype at passage 2 and passage 4. The clonal selection allowed to isolate cells with a higher multi-differentiation potential, but at the same time a lower proliferation rate in comparison to the whole population. Moreover, the clones express a higher amounts of stemness marker OCT4 and tendon specific transcription factor Scleraxis (SCX) mRNA, but a lower level of decorin (DCN). On the other hand, the number of cells obtained by clonal selection was extremely low and most of the clones were unable to reach a high number of passages in cultures. The presence of bFGF influences TCs morphology, enhance their proliferation rate and reduce their clonogenic ability. Interestingly, the expression of CD54, a known mesenchymal stem cell marker, is reduced in presence of bFGF at early passages. Nevertheless, bFGF does not affect the chondrogenic and osteogenic potential of TCs and the expression of tendon specific markers, while it was able to downregulate the OCT4 expression. This study showed that clonal selection enhance progenitors content in TCs populations, but the extremely low number of cells produced with this method could represent an insurmountable obstacle to its application in clinical approaches. We observed that the addition of bFGF to the

Nigerian population growth and its implications for economic development.

PubMed

Okpala, A O

1990-12-01

The population of Nigeria is growing at a rate of 3.75%/year indicating a doubling of the population every 22 years. Demographers estimated the population to be 91,178,000 in 1985. Even though population density is high (288 people/square mile), it is not equally distributed. It is highest in the south and southwest urban areas such as Lagos (1045 people/square mile) and lowest in the northeast (75 people/square mile). Moreover rural-urban migration is growing. A major reason for rural-urban migration is the dual nature of the economy in Nigeria. In urban areas, economic development brings about higher standards of living, but, in rural areas, a subsistence economy predominates. This coupled with rapid population growth results in small or no growth in per capita income. Only if the government were to integrate redistribution policies into complete economic development plans should it consider redistributing the population. It should stress rural development (e.g., incentives for firms to set up in rural areas). Further it should move some government offices to rural areas. The government also needs to adopt population policies encouraging the lowering of fertility levels. If it were to provide education through the secondary and prevocational education level free of charge, educated women will lower their fertility. Sex education should be included in the curriculum. Further the government must play an active role in family planning programs, especially educating rural women about family planning. It should also use the mass media to promote small family size, but it should not dictate family size. It also needs to recognize that population growth puts much pressure on the environment. For example, population growth causes soil erosion, nutrient exhaustion, rapid deforestation, and other problems which render the land unusable for agriculture.

Identification of Novel Growth Regulators in Plant Populations Expressing Random Peptides1[OPEN

PubMed Central

Bao, Zhilong; Clancy, Maureen A.

2017-01-01

The use of chemical genomics approaches allows the identification of small molecules that integrate into biological systems, thereby changing discrete processes that influence growth, development, or metabolism. Libraries of chemicals are applied to living systems, and changes in phenotype are observed, potentially leading to the identification of new growth regulators. This work describes an approach that is the nexus of chemical genomics and synthetic biology. Here, each plant in an extensive population synthesizes a unique small peptide arising from a transgene composed of a randomized nucleic acid sequence core flanked by translational start, stop, and cysteine-encoding (for disulfide cyclization) sequences. Ten and 16 amino acid sequences, bearing a core of six and 12 random amino acids, have been synthesized in Arabidopsis (Arabidopsis thaliana) plants. Populations were screened for phenotypes from the seedling stage through senescence. Dozens of phenotypes were observed in over 2,000 plants analyzed. Ten conspicuous phenotypes were verified through separate transformation and analysis of multiple independent lines. The results indicate that these populations contain sequences that often influence discrete aspects of plant biology. Novel peptides that affect photosynthesis, flowering, and red light response are described. The challenge now is to identify the mechanistic integrations of these peptides into biochemical processes. These populations serve as a new tool to identify small molecules that modulate discrete plant functions that could be produced later in transgenic plants or potentially applied exogenously to impart their effects. These findings could usher in a new generation of agricultural growth regulators, herbicides, or defense compounds. PMID:28807931

The Hispanic Population: 1990-2000 Growth and Change.

ERIC Educational Resources Information Center

Guzman, Betsy; McConnell, Eileen Diaz

2002-01-01

Points out significant changes in the Hispanic population between 1990 and 2000. Explores changes in the size and distribution of the Latino population using short-form data from the 1990 and 2000 censuses. Indicates significant growth of the Hispanic population who identify as 'other' Latino and the growing importance of the Midwest and South as…

Population growth and economic development: two new U.S. perspectives.

PubMed

Wulf, D; Klitsch, M

1986-01-01

This report compares the research paths of economic development reports by the US National Academy of Sciences (NAS) and the American Assembly of Columbia University. The NAS group, made up principally of economists and demographers, refrained from recommending population reduction targets, in contrast to the stronger terms of its 1971 report. A 1965 report by the Assembly spoke of population as a serious negative influence for economic development, political stability, and world peace, while the new report speaks of negative socioeconomic effects, and of the limiting of a person's right to control family size. The NAS agenda was established before the US delegation to the UN population conference in Mexico City retreated from declaring population growth to be a necessarily negative influencer of socioeconomic progress. The Assembly took the position that possible benefits of population growth would be far outweighed by factors such as resource depletion and women's health. The NAS maintained that growth might provide incentives for institutional adjustments (market development, investment in education) and control of growth should not be considered a substitute for such interventions. Both reports agree that control of fertility is a human right, but the NAS report examined the question of the acceptable degree of compulsion to be used to encourage couples. The Assembly objected to limiting access to family planning by defunding abortion programs oversease. Differences exist between the 2 reports in questins such as the negative impact of 1950's population growth, the synergistic effect of growth on many areas of human activity, the extent to which welfare of future generations is considered relevant today, and the adequacy of pure economic analysis in assessing need. Much study of population/development linkages is still required.

Population Growth in the 1990s: Patterns within the United States.

ERIC Educational Resources Information Center

Perry, Marc

2002-01-01

Examines population growth during the 1990s for a variety of geographic levels including regions, divisions, states, metropolitan areas, counties, and large cities. Compares growth rates for the 1990s with earlier decades to provide an historical context for present-day trends in population growth and decline. Discusses how differential population…

Effect of bacterial growth rate on bacteriophage population growth rate.

PubMed

Nabergoj, Dominik; Modic, Petra; Podgornik, Aleš

2018-04-01

It is important to understand how physiological state of the host influence propagation of bacteriophages (phages), due to the potential higher phage production needs in the future. In our study, we tried to elucidate the effect of bacterial growth rate on adsorption constant (δ), latent period (L), burst size (b), and bacteriophage population growth rate (λ). As a model system, a well-studied phage T4 and Escherichia coli K-12 as a host was used. Bacteria were grown in a continuous culture operating at dilution rates in the range between 0.06 and 0.98 hr -1 . It was found that the burst size increases linearly from 8 PFU·cell -1 to 89 PFU·cell -1 with increase in bacteria growth rate. On the other hand, adsorption constant and latent period were both decreasing from 2.6∙10 -9  ml·min -1 and 80 min to reach limiting values of 0.5 × 10 -9  ml·min -1 and 27 min at higher growth rates, respectively. Both trends were mathematically described with Michaelis-Menten based type of equation and reasons for such form are discussed. By applying selected equations, a mathematical equation for prediction of bacteriophage population growth rate as a function of dilution rate was derived, reaching values around 8 hr -1 at highest dilution rate. Interestingly, almost identical description can be obtained using much simpler Monod type equation and possible reasons for this finding are discussed. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Optimal growth entails risky localization in population dynamics

NASA Astrophysics Data System (ADS)

Gueudré, Thomas; Martin, David G.

2018-03-01

Essential to each other, growth and exploration are jointly observed in alive and inanimate entities, such as animals, cells or goods. But how the environment's structural and temporal properties weights in this balance remains elusive. We analyze a model of stochastic growth with time correlations and diffusive dynamics that sheds light on the way populations grow and spread over general networks. This model suggests natural explanations of empirical facts in econo-physics or ecology, such as the risk-return trade-off and the Zipf law. We conclude that optimal growth leads to a localized population distribution, but such risky position can be mitigated through the space geometry. These results have broad applicability and are subsequently illustrated over an empirical study of financial data.

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

ERIC Educational Resources Information Center

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…

Potential population growth and harmful effects on humans from bed bug populations exposed to different feeding regimes.

PubMed

Pereira, R M; Taylor, A S; Lehnert, M P; Koehler, P G

2013-06-01

Effects of host availability and feeding period on bed bugs, Cimex lectularius (L.) (Hemiptera: Cimicidae), were measured. Population growth and the potential harmful effect of bed bug populations on human hosts were modelled. Bloodmeal sizes were affected by both feeding length and frequency, with >2-fold difference between insects fed daily or weekly. Blood consumption increased >2-fold between bed bugs fed occasionally and often, and 1.5-fold between occasional and daily feeding. Bed bugs fed more often than once a week, potentially every 2-4 days. Egg production was associated with nutrition, being strongly correlated with blood consumption in the previous week. Bed bug populations can grow under different feeding regimes and are hard to control with <80% mortality. Bed bugs can survive and grow even in locations with a limited blood supply, where bed bug persistence may be important for the continual spread of populations. Persistence in non-traditional locations and a potential association with human pathogens increase the health risks of bed bugs. Potential blood loss as a result of a bed bug can have serious consequences because uncontrolled populations can reach harmful levels in 3-8 months. The reproduction potential of bed bug populations suggests serious consequences to human health and the need for efficacious control measures. © 2012 The Royal Entomological Society.

Population growth and economic development.

PubMed

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.

40 CFR 230.75 - Actions affecting plant and animal populations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Actions affecting plant and animal... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes in...

40 CFR 230.75 - Actions affecting plant and animal populations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Actions affecting plant and animal... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes in...

40 CFR 230.75 - Actions affecting plant and animal populations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Actions affecting plant and animal... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes in...

40 CFR 230.75 - Actions affecting plant and animal populations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Actions affecting plant and animal... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes in...

Simulated Warming Differentially Affects the Growth and Competitive Ability of Centaurea maculosa Populations from Home and Introduced Ranges

PubMed Central

He, Wei-Ming; Li, Jing-Ji; Peng, Pei-Hao

2012-01-01

Climate warming may drive invasions by exotic plants, thereby raising concerns over the risks of invasive plants. However, little is known about how climate warming influences the growth and competitive ability of exotic plants from their home and introduced ranges. We conducted a common garden experiment with an invasive plant Centaurea maculosa and a native plant Poa pratensis, in which a mixture of sand and vermiculite was used as a neutral medium, and contrasted the total biomass, competitive effects, and competitive responses of C. maculosa populations from Europe (home range) and North America (introduced range) under two different temperatures. The warming-induced inhibitory effects on the growth of C. maculosa alone were stronger in Europe than in North America. The competitive ability of C. maculosa plants from North America was greater than that of plants from Europe under the ambient condition whereas this competitive ability followed the opposite direction under the warming condition, suggesting that warming may enable European C. maculosa to be more invasive. Across two continents, warming treatment increased the competitive advantage instead of the growth advantage of C. maculosa, suggesting that climate warming may facilitate C. maculosa invasions through altering competitive outcomes between C. maculosa and its neighbors. Additionally, the growth response of C. maculosa to warming could predict its ability to avoid being suppressed by its neighbors. PMID:22303485

Simulated warming differentially affects the growth and competitive ability of Centaurea maculosa populations from home and introduced ranges.

PubMed

He, Wei-Ming; Li, Jing-Ji; Peng, Pei-Hao

2012-01-01

Climate warming may drive invasions by exotic plants, thereby raising concerns over the risks of invasive plants. However, little is known about how climate warming influences the growth and competitive ability of exotic plants from their home and introduced ranges. We conducted a common garden experiment with an invasive plant Centaurea maculosa and a native plant Poa pratensis, in which a mixture of sand and vermiculite was used as a neutral medium, and contrasted the total biomass, competitive effects, and competitive responses of C. maculosa populations from Europe (home range) and North America (introduced range) under two different temperatures. The warming-induced inhibitory effects on the growth of C. maculosa alone were stronger in Europe than in North America. The competitive ability of C. maculosa plants from North America was greater than that of plants from Europe under the ambient condition whereas this competitive ability followed the opposite direction under the warming condition, suggesting that warming may enable European C. maculosa to be more invasive. Across two continents, warming treatment increased the competitive advantage instead of the growth advantage of C. maculosa, suggesting that climate warming may facilitate C. maculosa invasions through altering competitive outcomes between C. maculosa and its neighbors. Additionally, the growth response of C. maculosa to warming could predict its ability to avoid being suppressed by its neighbors.

Future Coastal Population Growth and Exposure to Sea-Level Rise and Coastal Flooding - A Global Assessment

PubMed Central

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

Future coastal population growth and exposure to sea-level rise and coastal flooding--a global assessment.

PubMed

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

Population growth is a variable open to change

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Population properties affect inbreeding avoidance in moose

PubMed Central

Herfindal, Ivar; Haanes, Hallvard; Røed, Knut H.; Solberg, Erling J.; Markussen, Stine S.; Heim, Morten; Sæther, Bernt-Erik

2014-01-01

Mechanisms reducing inbreeding are thought to have evolved owing to fitness costs of breeding with close relatives. In small and isolated populations, or populations with skewed age- or sex distributions, mate choice becomes limited, and inbreeding avoidance mechanisms ineffective. We used a unique individual-based dataset on moose from a small island in Norway to assess whether inbreeding avoidance was related to population structure and size, expecting inbreeding avoidance to be greater in years with larger populations and even adult sex ratios. The probability that a potential mating event was realized was negatively related to the inbreeding coefficient of the potential offspring, with a stronger relationship in years with a higher proportion or number of males in the population. Thus, adult sex ratio and population size affect the degree of inbreeding avoidance. Consequently, conservation managers should aim for sex ratios that facilitate inbreeding avoidance, especially in small and isolated populations. PMID:25540152

Population properties affect inbreeding avoidance in moose.

PubMed

Herfindal, Ivar; Haanes, Hallvard; Røed, Knut H; Solberg, Erling J; Markussen, Stine S; Heim, Morten; Sæther, Bernt-Erik

2014-12-01

Mechanisms reducing inbreeding are thought to have evolved owing to fitness costs of breeding with close relatives. In small and isolated populations, or populations with skewed age- or sex distributions, mate choice becomes limited, and inbreeding avoidance mechanisms ineffective. We used a unique individual-based dataset on moose from a small island in Norway to assess whether inbreeding avoidance was related to population structure and size, expecting inbreeding avoidance to be greater in years with larger populations and even adult sex ratios. The probability that a potential mating event was realized was negatively related to the inbreeding coefficient of the potential offspring, with a stronger relationship in years with a higher proportion or number of males in the population. Thus, adult sex ratio and population size affect the degree of inbreeding avoidance. Consequently, conservation managers should aim for sex ratios that facilitate inbreeding avoidance, especially in small and isolated populations. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Memory and obesity affect the population dynamics of asexual freshwater planarians

NASA Astrophysics Data System (ADS)

Dunkel, Jörn; Talbot, Jared; Schötz, Eva-Maria

2011-04-01

Asexual reproduction in multicellular organisms is a complex biophysical process that is not yet well understood quantitatively. Here, we report a detailed population study for the asexual freshwater planarian Schmidtea mediterranea, which can reproduce via transverse fission due to a large stem cell contingent. Our long-term observations of isolated non-interacting planarian populations reveal that the characteristic fission waiting time distributions for head and tail fragments differ significantly from each other. The stochastic fission dynamics of tail fragments exhibits non-negligible memory effects, implying that an accurate mathematical description of future data should be based on non-Markovian tree models. By comparing the effective growth of non-interacting planarian populations with those of self-interacting populations, we are able to quantify the influence of interactions between flatworms and physical conditions on the population growth. A surprising result is the non-monotonic relationship between effective population growth rate and nutrient supply: planarians exhibit a tendency to become 'obese' if the feeding frequency exceeds a critical level, resulting in a decreased reproduction activity. This suggests that these flatworms, which possess many genes homologous to those of humans, could become a new model system for studying dietary effects on reproduction and regeneration in multicellular organisms.

Stochastic dynamics and logistic population growth

NASA Astrophysics Data System (ADS)

Méndez, Vicenç; Assaf, Michael; Campos, Daniel; Horsthemke, Werner

2015-06-01

The Verhulst model is probably the best known macroscopic rate equation in population ecology. It depends on two parameters, the intrinsic growth rate and the carrying capacity. These parameters can be estimated for different populations and are related to the reproductive fitness and the competition for limited resources, respectively. We investigate analytically and numerically the simplest possible microscopic scenarios that give rise to the logistic equation in the deterministic mean-field limit. We provide a definition of the two parameters of the Verhulst equation in terms of microscopic parameters. In addition, we derive the conditions for extinction or persistence of the population by employing either the momentum-space spectral theory or the real-space Wentzel-Kramers-Brillouin approximation to determine the probability distribution function and the mean time to extinction of the population. Our analytical results agree well with numerical simulations.

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

Treesearch

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,...

Endogenous population growth may imply chaos.

PubMed

Prskawetz, A; Feichtinger, G

1995-01-01

The authors consider a discrete-time neoclassical growth model with an endogenous rate of population growth. The resulting one-dimensional map for the capital intensity has a tilted z-shape. Using the theory of nonlinear dynamical systems, they obtain numerical results on the qualitative behavior of time paths for changing parameter values. Besides stable and periodic solutions, erratic time paths may result. In particular, myopic and far-sighted economies--assumed to be characterized by low and high savings rate respectively--are characterized by stable per capita capital stocks, while solutions with chaotic windows exist between these two extremes.

[African population growth: status and prospects].

PubMed

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

Predators select against high growth rates and risk-taking behaviour in domestic trout populations.

PubMed

Biro, Peter A; Abrahams, Mark V; Post, John R; Parkinson, Eric A

2004-11-07

Domesticated (farm) salmonid fishes display an increased willingness to accept risk while foraging, and achieve high growth rates not observed in nature. Theory predicts that elevated growth rates in domestic salmonids will result in greater risk-taking to access abundant food, but low survival in the presence of predators. In replicated whole-lake experiments, we observed that domestic trout (selected for high growth rates) took greater risks while foraging and grew faster than a wild strain. However, survival consequences for greater growth rates depended upon the predation environment. Domestic trout experienced greater survival when risk was low, but lower survival when risk was high. This suggests that animals with high intrinsic growth rates are selected against in populations with abundant predators, explaining the absence of such phenotypes in nature. This is, to our knowledge, the first large-scale field experiment to directly test this theory and simultaneously quantify the initial invasibility of domestic salmonid strains that escape into the wild from aquaculture operations, and the ecological conditions affecting their survival.

Genetic diversity affects the strength of population regulation in a marine fish.

PubMed

Johnson, D W; Freiwald, J; Bernardi, G

2016-03-01

Variation is an essential feature of biological populations, yet much of ecological theory treats individuals as though they are identical. This simplifying assumption is often justified by the perception that variation among individuals does not have significant effects on the dynamics of whole populations. However, this perception may be skewed by a historic focus on studying single populations. A true evaluation of the extent to which among-individual variation affects the dynamics of populations requires the study of multiple populations. In this study, we examined variation in the dynamics of populations of a live-bearing, marine fish (black surfperch; Embiotoca jacksoni). In collaboration with an organization of citizen scientists (Reef Check California), we were able to examine the dynamics of eight populations that were distributed throughout approximately 700 km of coastline, a distance that encompasses much of this species' range. We hypothesized that genetic variation within a local population would be related to the intensity of competition and to the strength of population regulation. To test this hypothesis, we examined whether genetic diversity (measured by the diversity of mitochondrial DNA haplotypes) was related to the strength of population regulation. Low-diversity populations experienced strong density dependence in population growth rates and population sizes were regulated much more tightly than they were in high-diversity populations. Mechanisms that contributed to this pattern include links between genetic diversity, habitat use, and spatial crowding. On average, low-diversity populations used less of the available habitat and exhibited greater spatial clustering (and more intense competition) for a given level of density (measured at the scale of the reef). Although the populations we studied also varied with respect to exogenous characteristics (habitat complexity, densities of predators, and interspecific competitors), none of these

The New Population Debate: Two Views on Population Growth and Economic Development. Population Trends and Public Policy, Number 7.

ERIC Educational Resources Information Center

King, Timothy; Kelley, Allen C.

Articles representing two views on the issue of rapid population growth and economic development are presented. Although the authors present different perspectives, they agree on many of the fundamentals. For example, both reject alarmism about impending "population explosions" and the use of population as a scapegoat for all Third World…

Krill population dynamics in the Scotia Sea: variability in growth and mortality within a single population

NASA Astrophysics Data System (ADS)

Reid, K.; Murphy, E. J.; Loeb, V.; Hewitt, R. P.

2002-07-01

Understanding the demographics of Antarctic krill over large scales may be complicated by regional differences in the processes that govern population structure. The influence of regional differences in growth and mortality on population size structure was examined using data on the length-frequency distribution of krill in the Scotia Sea using samples from the South Shetland Islands and South Georgia collected annually from 1991 to 2000. A correction function, which took account of the higher growth rate at South Georgia, produced a consistent similarity in the position of the modal size classes that was not present in the raw data. Optimising the mortality rate, to minimise the differences in the growth corrected length-frequency distribution, suggested a higher mortality rate at South Georgia that the South Shetlands. The intra-specific variations in growth and mortality rates are consistent with published values and with other Euphausiids species. Having accounted for the demographic plasticity, it is apparent that strong recruitment of the smallest size class of krill is represented in both populations simultaneously. It appears that first-year krill are advected into different regions of the Scotia Sea where the resultant population size structure is determined by regional differences in growth and mortality. The majority of the commercial harvest of krill in the Antarctic occurs in a relatively small number of regional fisheries within the Scotia Sea and is managed using population models based on a single set of demographic parameters. Where substantial differences in these parameters exist between fishing areas, the calculation of catch limits should take these differences into account.

Wolf population dynamics in the U.S. Northern Rocky Mountains are affected by recruitment and human-caused mortality

USGS Publications Warehouse

Gude, J.A.; Mitchell, M.S.; Russell, R.E.; Sime, C.A.; Bangs, E.E.; Mech, L.D.; Ream, R.R.

2012-01-01

Reliable analyses can help wildlife managers make good decisions, which are particularly critical for controversial decisions such as wolf (Canis lupus) harvest. Creel and Rotella (2010) recently predicted substantial population declines in Montana wolf populations due to harvest, in contrast to predictions made by Montana Fish, Wildlife and Parks (MFWP). We replicated their analyses considering only those years in which field monitoring was consistent, and we considered the effect of annual variation in recruitment on wolf population growth. Rather than assuming constant rates, we used model selection methods to evaluate and incorporate models of factors driving recruitment and human-caused mortality rates in wolf populations in the Northern Rocky Mountains. Using data from 27 area-years of intensive wolf monitoring, we show that variation in both recruitment and human-caused mortality affect annual wolf population growth rates and that human-caused mortality rates have increased with the sizes of wolf populations. We document that recruitment rates have decreased over time, and we speculate that rates have decreased with increasing population sizes and/or that the ability of current field resources to document recruitment rates has recently become less successful as the number of wolves in the region has increased. Estimates of positive wolf population growth in Montana from our top models are consistent with field observations and estimates previously made by MFWP for 2008-2010, whereas the predictions for declining wolf populations of Creel and Rotella (2010) are not. Familiarity with limitations of raw data, obtained first-hand or through consultation with scientists who collected the data, helps generate more reliable inferences and conclusions in analyses of publicly available datasets. Additionally, development of efficient monitoring methods for wolves is a pressing need, so that analyses such as ours will be possible in future years when fewer resources

Why Population Matters, 1996.

ERIC Educational Resources Information Center

Population Action International, Washington, DC.

Population growth around the world affects Americans through its impact on economy, environment, safety, and health, and the condition of the world children will inherit. The cumulative evidence is strong that current rates of population growth pose significant and interacting risks to human well-being and are a legitimate concern for Americans.…

The model of fungal population dynamics affected by nystatin

NASA Astrophysics Data System (ADS)

Voychuk, Sergei I.; Gromozova, Elena N.; Sadovskiy, Mikhail G.

Fungal diseases are acute problems of the up-to-day medicine. Significant increase of resistance of microorganisms to the medically used antibiotics and a lack of new effective drugs follows in a growth of dosage of existing chemicals to solve the problem. Quite often such approach results in side effects on humans. Detailed study of fungi-antibiotic dynamics can identify new mechanisms and bring new ideas to overcome the microbial resistance with a lower dosage of antibiotics. In this study, the dynamics of the microbial population under antibiotic treatment was investigated. The effects of nystatin on the population of Saccharomyces cerevisiae yeasts were used as a model system. Nystatin effects were investigated both in liquid and solid media by viability tests. Dependence of nystatin action on osmotic gradient was evaluated in NaCl solutions. Influences of glucose and yeast extract were additionally analyzed. A "stepwise" pattern of the cell death caused by nystatin was the most intriguing. This pattern manifested in periodical changes of the stages of cell death against stages of resistance to the antibiotic. The mathematical model was proposed to describe cell-antibiotic interactions and nystatin viability effects in the liquid medium. The model implies that antibiotic ability to cause a cells death is significantly affected by the intracellular compounds, which came out of cells after their osmotic barriers were damaged

COULD ETHINYL ESTRADIOL AFFECT THE POPULATION BIOLOGY OF CUNNER, TAUTOGOLABRUS ADSPERSUS

EPA Science Inventory

Endocrine disrupting chemicals in the environment may disturb the population dynamics of wildlife by affecting reproductive output and embryonic development of organisms. This study used a population model to evaluate whether ethinyl estradiol (EE2 could affect cunner Tautogolabr...

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

PubMed

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.

Life-History and Spatial Determinants of Somatic Growth Dynamics in Komodo Dragon Populations

PubMed Central

Laver, Rebecca J.; Purwandana, Deni; Ariefiandy, Achmad; Imansyah, Jeri; Forsyth, David; Ciofi, Claudio; Jessop, Tim S.

2012-01-01

Somatic growth patterns represent a major component of organismal fitness and may vary among sexes and populations due to genetic and environmental processes leading to profound differences in life-history and demography. This study considered the ontogenic, sex-specific and spatial dynamics of somatic growth patterns in ten populations of the world’s largest lizard the Komodo dragon (Varanus komodoensis). The growth of 400 individual Komodo dragons was measured in a capture-mark-recapture study at ten sites on four islands in eastern Indonesia, from 2002 to 2010. Generalized Additive Mixed Models (GAMMs) and information-theoretic methods were used to examine how growth rates varied with size, age and sex, and across and within islands in relation to site-specific prey availability, lizard population density and inbreeding coefficients. Growth trajectories differed significantly with size and between sexes, indicating different energy allocation tactics and overall costs associated with reproduction. This leads to disparities in maximum body sizes and longevity. Spatial variation in growth was strongly supported by a curvilinear density-dependent growth model with highest growth rates occurring at intermediate population densities. Sex-specific trade-offs in growth underpin key differences in Komodo dragon life-history including evidence for high costs of reproduction in females. Further, inverse density-dependent growth may have profound effects on individual and population level processes that influence the demography of this species. PMID:23028983

Spatial variability and macro‐scale drivers of growth for native and introduced Flathead Catfish populations

USGS Publications Warehouse

Massie, Danielle L.; Smith, Geoffrey; Bonvechio, Timothy F.; Bunch, Aaron J.; Lucchesi, David O.; Wagner, Tyler

2018-01-01

Quantifying spatial variability in fish growth and identifying large‐scale drivers of growth are fundamental to many conservation and management decisions. Although fish growth studies often focus on a single population, it is becoming increasingly clear that large‐scale studies are likely needed for addressing transboundary management needs. This is particularly true for species with high recreational value and for those with negative ecological consequences when introduced outside of their native range, such as the Flathead Catfish Pylodictis olivaris. This study quantified growth variability of the Flathead Catfish across a large portion of its contemporary range to determine whether growth differences existed between habitat types (i.e., reservoirs and rivers) and between native and introduced populations. Additionally, we investigated whether growth parameters varied as a function of latitude and time since introduction (for introduced populations). Length‐at‐age data from 26 populations across 11 states in the USA were modeled using a Bayesian hierarchical von Bertalanffy growth model. Population‐specific growth trajectories revealed large variation in Flathead Catfish growth and relatively high uncertainty in growth parameters for some populations. Relatively high uncertainty was also evident when comparing populations and when quantifying large‐scale patterns. Growth parameters (Brody growth coefficient [K] and theoretical maximum average length [L∞]) were not different (based on overlapping 90% credible intervals) between habitat types or between native and introduced populations. For populations within the introduced range of Flathead Catfish, latitude was negatively correlated with K. For native populations, we estimated an 85% probability that L∞ estimates were negatively correlated with latitude. Contrary to predictions, time since introduction was not correlated with growth parameters in introduced populations of Flathead Catfish

Drought tolerance and growth in populations of a wide-ranging tree species indicate climate change risks for the boreal north.

PubMed

Montwé, David; Isaac-Renton, Miriam; Hamann, Andreas; Spiecker, Heinrich

2016-02-01

Choosing drought-tolerant planting stock in reforestation programs may help adapt forests to climate change. To inform such reforestation strategies, we test lodgepole pine (Pinus contorta Doug. ex Loud. var latifolia Englm.) population response to drought and infer potential benefits of a northward transfer of seeds from drier, southern environments. The objective is addressed by combining dendroecological growth analysis with long-term genetic field trials. Over 500 trees originating from 23 populations across western North America were destructively sampled in three experimental sites in southern British Columbia, representing a climate warming scenario. Growth after 32 years from provenances transferred southward or northward over long distances was significantly lower than growth of local populations. All populations were affected by a severe natural drought event in 2002. The provenances from the most southern locations showed the highest drought tolerance but low productivity. Local provenances were productive and drought tolerant. Provenances from the boreal north showed lower productivity and less drought tolerance on southern test sites than all other sources, implying that maladaptation to drought may prevent boreal populations from taking full advantage of more favorable growing conditions under projected climate change. © 2015 John Wiley & Sons Ltd.

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

PubMed

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.

The Between-Population Genetic Architecture of Growth, Maturation, and Plasticity in Atlantic Salmon

PubMed Central

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

2014-01-01

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. PMID:24473933

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

PubMed

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.

Two Novel SNPs of PPARγ Significantly Affect Weaning Growth Traits of Nanyang Cattle.

PubMed

Huang, Jieping; Chen, Ningbo; Li, Xin; An, Shanshan; Zhao, Minghui; Sun, Taihong; Hao, Ruijie; Ma, Yun

2018-01-02

Peroxisome-proliferator-activated receptor gamma (PPARγ) is a key transcription factor that controls adipocyte differentiation and energy in mammals. Therefore, PPARγ is a potential factor influencing animal growth traits. This study primarily evaluates PPARγ as candidate gene for growth traits of cattle and identifies potential molecular marker for cattle breeding. Per previous studies, PPARγ mRNA was mainly expressed at extremely high levels in adipose tissues as shown by quantitative real-time polymerase chain reaction analysis. Three novel SNPs of the bovine PPARγ gene were identified in 514 individuals from six Chinese cattle breeds: SNP1 (AC_000179.1 g.57386668 C > G) in intron 2 and SNP2 (AC_000179.1 g.57431964 C > T) and SNP3 (AC_000179.1 g.57431994 T > C) in exon 7. The present study also investigated genetic characteristics of these SNP loci in six populations. Association analysis showed that SNP1 and SNP3 loci significantly affect weaning growth traits, especially body weight of Nanyang cattle. These results revealed that SNP1 and SNP3 are potential molecular markers for cattle breeding.

Growth of Salmonella on sprouting alfalfa seeds as affected by the inoculum size, native microbial load and Pseudomonas fluorescens 2-79.

PubMed

Liao, C-H

2008-02-01

To investigate the growth of salmonellae on sprouting alfalfa seeds as affected by the inoculum size, microbial load and Pseudomonas fluorescens 2-79. Alfalfa seeds pre-inoculated with < or =10(1)-10(3) CFU g(-1) of salmonellae and with or without Ps. fluorescens 2-79 were sprouted in glass jars and the population of salmonellae were determined daily for up to 6 days. The population of salmonellae on germinating seeds reached the maximum 2-3 days after sprouting when total bacterial count reached the maximum (10(9) CFU g(-1)). The population of salmonellae on sprouting seeds not treated with Ps. fluorescens 2-79 showed a net increase of 3-4 log units. However, the population of salmonellae on alfalfa seeds treated with Ps. fluorescens 2-79 showed a net increase of only 1-2 log units. Disinfection of seeds with calcium hypochlorite enhanced the growth of salmonellae. Treatment of seeds with Ps. fluorescens 2-79 reduced the growth of salmonellae by 2-3 log units. The potential of Ps. fluorescens 2-79 as a biological agent for use in control of salmonellae on sprouting seeds was demonstrated and warrants further investigation.

Apple dwarfing rootstocks and interstocks affect the type of growth units produced during the annual growth cycle: precocious transition to flowering affects the composition and vigour of annual shoots.

PubMed

Seleznyova, Alla N; Tustin, D Stuart; Thorp, T Grant

2008-04-01

Precocious flowering in apple trees is often associated with a smaller tree size. The hypothesis was tested that floral evocation in axillary buds, induced by dwarfing rootstocks, reduces the vigour of annual shoots developing from these buds compared with shoots developing from vegetative buds. The experimental system provided a wide range of possible tree vigour using 'Royal Gala' scions and M.9 (dwarfing) and MM.106 (non-dwarfing) as rootstocks and interstocks. Second-year annual shoots were divided into growth units corresponding to periods (flushes) of growth namely, vegetative spur, extension growth unit, uninterrupted growth unit, floral growth unit (bourse) and extended bourse. The differences between the floral and vegetative shoots were quantified by the constituent growth units produced. The dwarfing influence was expressed, firstly, in reduced proportions of shoots that contained at least one extension growth unit and secondly, in reduced proportions of bicyclic shoots (containing two extension growth units) and shoots with an uninterrupted growth unit. In treatments where floral shoots were present, they were markedly less vigorous than vegetative shoots with respect to both measures. In treatments with M.9 rootstock, vegetative and floral shoots produced on average 0.52 and 0.17 extension growth units, compared with 0.77 extension growth units per shoot in the MM.106 rootstock treatment. Remarkably, the number of nodes per extension growth unit was not affected by the rootstock/interstock treatments. These results showed that rootstocks/interstocks affect the type of growth units produced during the annual growth cycle, reducing the number of extension growth units, thus affecting the composition and vigour of annual shoots. This effect is particularly amplified by the transition to flowering induced by dwarfing rootstocks. The division of annual shoot into growth units will also be useful for measuring and modelling effects of age on apple tree

Population Growth of Varroa destructor (Acari: Varroidae) in Colonies of Russian and Unselected Honey Bee (Hymenoptera: Apidae) Stocks as Related to Numbers of Foragers With Mites.

PubMed

DeGrandi-Hoffman, Gloria; Ahumada, Fabiana; Danka, Robert; Chambers, Mona; DeJong, Emily Watkins; Hidalgo, Geoff

2017-06-01

Varroa (Varroa destructor Anderson and Trueman) is an external parasite of honey bees (Apis mellifera L.) and a leading cause of colony losses worldwide. Varroa populations can be controlled with miticides, but mite-resistant stocks such as the Russian honey bee (RHB) also are available. Russian honey bee and other mite-resistant stocks limit Varroa population growth by affecting factors that contribute to mite reproduction. However, mite population growth is not entirely due to reproduction. Numbers of foragers with mites (FWM) entering and leaving hives also affect the growth of mite populations. If FWM significantly contribute to Varroa population growth, mite numbers in RHB colonies might not differ from unselected lines (USL). Foragers with mites were monitored at the entrances of RHB and USL hives from August to November, 2015, at two apiary sites. At site 1, RHB colonies had fewer FWM than USL and smaller phoretic mite populations. Russian honey bee also had fewer infested brood cells and lower percentages with Varroa offspring than USL. At site 2, FWM did not differ between RHB and USL, and phoretic mite populations were not significantly different. At both sites, there were sharp increases in phoretic mite populations from September to November that corresponded with increasing numbers of FWM. Under conditions where FWM populations are similar between RHB and USL, attributes that contribute to mite resistance in RHB may not keep Varroa population levels below that of USL. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by US Government employees and is in the public domain in the US.

Parameter Estimates in Differential Equation Models for Population Growth

ERIC Educational Resources Information Center

Winkel, Brian J.

2011-01-01

We estimate the parameters present in several differential equation models of population growth, specifically logistic growth models and two-species competition models. We discuss student-evolved strategies and offer "Mathematica" code for a gradient search approach. We use historical (1930s) data from microbial studies of the Russian biologist,…

Tourism in Austria: biodiversity, environmental sustainability, and growth issues.

PubMed

Malik, Muhammad Asad Saleem; Shah, Syed Asim; Zaman, Khalid

2016-12-01

This study examined the long-run and causal relationships between international tourism, biodiversity loss, environmental sustainability, and specific growth factors under the premises of sustainable tourism in Austria, by using a consistent time series data from 1975 to 2015. The results reveal that inbound tourism, per capita income, and population density affected the potential habitat area while population density largely affected the food production in a country. Inbound tourism and population density both deteriorate the environmental quality in a form of increasing carbon dioxide (CO 2 ) emissions and fossil fuel energy consumption while per capita income reduces the fossil fuel energy consumption. Food exports increase per capita income, while food imports and population density both decrease economic growth. Inbound tourism and economic growth advance population density while forest area and food exports decrease the population density. The study supports growth-led tourism and growth-led food production in a country.

A Stochastic Super-Exponential Growth Model for Population Dynamics

NASA Astrophysics Data System (ADS)

Avila, P.; Rekker, A.

2010-11-01

A super-exponential growth model with environmental noise has been studied analytically. Super-exponential growth rate is a property of dynamical systems exhibiting endogenous nonlinear positive feedback, i.e., of self-reinforcing systems. Environmental noise acts on the growth rate multiplicatively and is assumed to be Gaussian white noise in the Stratonovich interpretation. An analysis of the stochastic super-exponential growth model with derivations of exact analytical formulae for the conditional probability density and the mean value of the population abundance are presented. Interpretations and various applications of the results are discussed.

Effects of forest management on density, survival, and population growth of wood thrushes

USGS Publications Warehouse

Powell, L.A.; Lang, J.D.; Conroy, M.J.; Krementz, D.G.

2000-01-01

Loss and alteration of breeding habitat have been proposed as causes of declines in several Neotropical migrant bird populations. We conducted a 4-year study to determine the effects of winter prescribed burning and forest thinning on breeding wood thrush (Hylocichla mustelina) populations at the Piedmont National Wildlife Refuge (PNWR) in Georgia. We estimated density, adult and juvenile survival rates, and apparent annual survival using transect surveys, radiotelemetry, and mist netting. Burning and thinning did not cause lower densities (P = 0.25); wood thrush density ranged from 0.15 to 1.30 pairs/10 ha. No radiomarked male wood thrushes (n = 68) died during the 4 years, but female (n = 63) weekly survival was 0.981 ? 0.014 (SE) for females (n = 63) and 0.976 ? 0.010 for juveniles (n = 38). Apparent annual adult survival was 0.579 (SE = 0.173). Thinning and prescribed burning did not reduce adult or juvenile survival during the breeding season or apparent annual adult survival. Annual population growth (lambda) at PNWR was 1.00 (95% confidence interval = 0.32--1.63), and the considerable uncertainty in this prediction underscores the need for long term monitoring to effectively manage Neotropical migrants. Population growth increased on experimental compartments after the burn and thin (95% CI before = 0.91--0.97, after = 0.98--1.05), while control compartment declined (before = 0.98--1.05, after = 0.87--0.92). We found no evidence that the current management regime at PNWR, designed to improve red-cockaded woodpecker (Picoides borealis) habitat, negatively affected wood thrushes.

Discerning environmental factors affecting current tree growth in Central Europe.

PubMed

Cienciala, Emil; Russ, Radek; Šantrůčková, Hana; Altman, Jan; Kopáček, Jiří; Hůnová, Iva; Štěpánek, Petr; Oulehle, Filip; Tumajer, Jan; Ståhl, Göran

2016-12-15

We examined the effect of individual environmental factors on the current spruce tree growth assessed from a repeated country-level statistical landscape (incl. forest) survey in the Czech Republic. An extensive set of variables related to tree size, competition, site characteristics including soil texture, chemistry, N deposition and climate was tested within a random-effect model to explain growth in the conditions of dominantly managed forest ecosystems. The current spruce basal area increment was assessed from two consecutive landscape surveys conducted in 2008/2009 and six years later in 2014/2015. Tree size, age and competition within forest stands were found to be the dominant explanatory variables, whereas the expression of site characteristics, environmental and climatic drives was weaker. The significant site variables affecting growth included soil C/N ratio and soil exchangeable acidity (pH KCl; positive response) reflecting soil chemistry, long-term N-deposition (averaged since 1975) in combination with soil texture (clay content) and Standardized Precipitation Index (SPI), a drought index expressing moisture conditions. Sensitivity of growth to N-deposition was positive, although weak. SPI was positively related to and significant in explaining tree growth when expressed for the growth season. Except SPI, no significant relation of growth was determined to altitude-related variables (temperature, growth season length). We identified the current spruce growth optimum at elevations about 800ma.s.l. or higher in the conditions of the country. This suggests that at lower elevations, limitation by a more pronounced water deficit dominates, whereas direct temperature limitation may concern the less frequent higher elevations. The mixed linear model of spruce tree growth explained 55 and 65% of the variability with fixed and random effects included, respectively, and provided new insights on the current spruce tree growth and factors affecting it within the

Adult survival and population growth rate in Colorado big brown bats (Eptesicus fuscus)

USGS Publications Warehouse

O'Shea, T.J.; Ellison, L.E.; Stanley, T.R.

2011-01-01

We studied adult survival and population growth at multiple maternity colonies of big brown bats (Eptesicus fuscus) in Fort Collins, Colorado. We investigated hypotheses about survival using information-theoretic methods and mark-recapture analyses based on passive detection of adult females tagged with passive integrated transponders. We constructed a 3-stage life-history matrix model to estimate population growth rate (??) and assessed the relative importance of adult survival and other life-history parameters to population growth through elasticity and sensitivity analysis. Annual adult survival at 5 maternity colonies monitored from 2001 to 2005 was estimated at 0.79 (95% confidence interval [95% CI] = 0.77-0.82). Adult survival varied by year and roost, with low survival during an extreme drought year, a finding with negative implications for bat populations because of the likelihood of increasing drought in western North America due to global climate change. Adult survival during winter was higher than in summer, and mean life expectancies calculated from survival estimates were lower than maximum longevity records. We modeled adult survival with recruitment parameter estimates from the same population. The study population was growing (?? = 1.096; 95% CI = 1.057-1.135). Adult survival was the most important demographic parameter for population growth. Growth clearly had the highest elasticity to adult survival, followed by juvenile survival and adult fecundity (approximately equivalent in rank). Elasticity was lowest for fecundity of yearlings. The relative importances of the various life-history parameters for population growth rate are similar to those of large mammals. ?? 2011 American Society of Mammalogists.

A model of northern pintail productivity and population growth rate

USGS Publications Warehouse

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.

The role of density-dependent individual growth in the persistence of freshwater salmonid populations.

PubMed

Vincenzi, Simone; Crivelli, Alain J; Jesensek, Dusan; De Leo, Giulio A

2008-06-01

Theoretical and empirical models of populations dynamics have paid little attention to the implications of density-dependent individual growth on the persistence and regulation of small freshwater salmonid populations. We have therefore designed a study aimed at testing our hypothesis that density-dependent individual growth is a process that enhances population recovery and reduces extinction risk in salmonid populations in a variable environment subject to disturbance events. This hypothesis was tested in two newly introduced marble trout (Salmo marmoratus) populations living in Slovenian streams (Zakojska and Gorska) subject to severe autumn floods. We developed a discrete-time stochastic individual-based model of population dynamics for each population with demographic parameters and compensatory responses tightly calibrated on data from individually tagged marble trout. The occurrence of severe flood events causing population collapses was explicitly accounted for in the model. We used the model in a population viability analysis setting to estimate the quasi-extinction risk and demographic indexes of the two marble trout populations when individual growth was density-dependent. We ran a set of simulations in which the effect of floods on population abundance was explicitly accounted for and another set of simulations in which flood events were not included in the model. These simulation results were compared with those of scenarios in which individual growth was modelled with density-independent Von Bertalanffy growth curves. Our results show how density-dependent individual growth may confer remarkable resilience to marble trout populations in case of major flood events. The resilience to flood events shown by the simulation results can be explained by the increase in size-dependent fecundity as a consequence of the drop in population size after a severe flood, which allows the population to quickly recover to the pre-event conditions. Our results suggest

Survival and growth of Enterobacter sakazakii in infant cereal as affected by composition, reconstitution liquid, and storage temperature.

PubMed

Lin, Li-Chun; Beuchat, Larry R

2007-06-01

Invasive infections caused by Enterobacter sakazakii have occurred predominantly in low-birth-weight neonates and infants younger than 2 months of age. However, infections have also occurred in healthy infants up to 8 months of age and in immunocompromised children up to 4 years of age. The ability of E. sakazakii to survive and grow in infant cereals as affected by composition of the cereal, composition of the reconstitution liquid, and temperature is unknown. A study was done to determine the survival and growth characteristics of E. sakazakii initially at populations of 0.005 and 0.52 CFU/ml of infant rice cereal, oatmeal cereal, or rice with mixed fruit cereal reconstituted with water, milk, or apple juice. Reconstituted cereals were stored at 4, 12, 21, and 30 degrees C, and populations were monitored for up to 72 h. Growth did not occur in reconstituted cereals stored at 4 degrees C or in cereals reconstituted with apple juice and stored at 12 degrees C. Populations (> or =1 CFU/ml) were detected in cereals reconstituted with water or milk and stored at 12, 21, and 30 degres C for 24, 8, and 4 h, respectively. The composition of infant cereals did not markedly affect the survival or growth of E. sakazakii in reconstituted cereals. Populations of E. sakazakii in reconstituted cereal decreased with increases in populations of mesophilic aerobic microflora up to 8 to 9 log CFU/ml, which was concurrent with decreases in pH. E. sakazakii, initially at 2.62 log CFU/ml of rice cereal reconstituted with apple juice (pH 4.32), survived at 40C for at least 14 days. The pathogen grew at 21 and 30 degrees C within 2 days and then decreased to undetectable levels (<1 CFU/10 ml) in cereal stored at 21 degrees C for 5 days or 30'C for 4 days. Initially, at 7.32 log CFU/ml, E. sakazakii was detected in rice cereal stored at 4 degrees C for 50 days. It is recommended that reconstituted infant cereals stored at 21 or 30 degrees C be discarded within 4 h after preparation or

Risk factors for injuries in landslide- and flood-affected populations in Uganda.

PubMed

Agrawal, Shreya; Gopalakrishnan, Tisha; Gorokhovich, Yuri; Doocy, Shannon

2013-08-01

The frequency of occurrence of natural disasters has increased over the past several decades, which necessitates a better understanding of human vulnerability, particularly in low-resource settings. This paper assesses risk factors for injury in the March 2010 floods and landslides in Eastern Uganda, and compares the effects of location, injury type, and severity. A stratified cluster survey of the disaster-affected populations was conducted five months after onset of the disasters. Probability proportional to size sampling was used to sample 800 households, including 400 affected by floods in Butaleja District and 400 affected by landslides in Bududa District. Flood- and landslide-affected populations were surveyed in July 2010 using a stratified cluster design. The odds of injury were 65% higher in the flood-affected groups than the landslide-affected groups in a logistic regression (OR = 0.35; 95% CI, 0.24-0.52; P < .001). The injury rate was greater in individuals under 42 years of age, and location of injury was a contributing factor. More people were injured in the flood-affected population as compared with the landslide-affected population, and injuries were more severe. This study illustrates differences between populations injured by flood and landslide disasters that occurred simultaneously in Eastern Uganda in 2010. In areas where landslides are prone to occur due to massive rainfalls or floods, preventative measures, such as early warning systems and evacuation, are more likely to increase the likelihood of people surviving, while for areas with massive floods, immediate and effective medical attention can save lives and improve injury outcomes.

Trends in the growth of population and labour force in Pakistan.

PubMed

Hashmi, S S

1990-01-01

Trends in the growth of the population and labor force in Pakistan are examined and future prospects for growth of population and labor, particularly agriculture, are estimated. The definition of labor force as employed or seeking work after a short period of employment has led to a great disparity in results for women in the labor force. Past trends in population growth reflected a growth rate of 1.6% for the 1950's, and 2.4% in 1960. The population rose to 84.3 million in 1981 from 42.6 million in 1961, which intercensally was an increase of 3.6% per annum for 1961-72 and 3.1% per annum for 1972-81. The estimated rate for 1981-86 was 2.9%/year. The rural population doubled and the urban tripled. There was a net migration of 2.123 million to urban areas reported in the 1981 census. There is also evidence of a high sex ratio. Balochistan (7.1%) and Sindh (3.6%) provinces have the highest growth rates. Although the largest population is in the Punjab, the growth is the lowest at 2.7%. The population is primarily young -- 44.5% 15 years in 1981, which is the highest in the world. Under high, medium, and low levels of fertility, prospective trends are estimated for 2006 and 2031, and by sex every 5 years from 1981. Population under high fertility is expected to reach 270 million by 2031, which is 3.39 persons/hectare. The population/hectare of land under cultivation was 4.25 in 1981 and is expected to rise to 13.49 persons/hectare in 2031. 11 million acres could be brought under cultivation to reduce the ratio. However, there are ecological considerations as well as an employment problem. The dependency ratio under the high variant will decline from 76.8 persons 0-14 and 65 years/100 persons 15-64 years in 1986 to 70.3 in 2006 which is still considerably higher than other developing countries. It is suggested that replacement level fertility be attained as soon as possible. Under low fertility, replacement level can be reached by 2011 with strong political commitment

Growth dynamics and the evolution of cooperation in microbial populations

NASA Astrophysics Data System (ADS)

Cremer, Jonas; Melbinger, Anna; Frey, Erwin

2012-02-01

Microbes providing public goods are widespread in nature despite running the risk of being exploited by free-riders. However, the precise ecological factors supporting cooperation are still puzzling. Following recent experiments, we consider the role of population growth and the repetitive fragmentation of populations into new colonies mimicking simple microbial life-cycles. Individual-based modeling reveals that demographic fluctuations, which lead to a large variance in the composition of colonies, promote cooperation. Biased by population dynamics these fluctuations result in two qualitatively distinct regimes of robust cooperation under repetitive fragmentation into groups. First, if the level of cooperation exceeds a threshold, cooperators will take over the whole population. Second, cooperators can also emerge from a single mutant leading to a robust coexistence between cooperators and free-riders. We find frequency and size of population bottlenecks, and growth dynamics to be the major ecological factors determining the regimes and thereby the evolutionary pathway towards cooperation.

Stable, semi-stable populations and growth potential.

PubMed

Bourgeois-Pichat, J

1971-07-01

Abstract Starting from the definition of a Malthusian population given by Alfred J. Lotka, the author recalls how the concept of stable population is introduced in demography, first as a particular case of stable populations, and secondly as a limit of a demographic evolutionary process in which female age-specific fertility rates and age-specific mortality rates remain constant. Then he defines a new concept: the semi-stable population which is a population with a constant age distribution. He shows that such a population coincides at any point of time with the stable population corresponding to the mortality and the fertility at this point of time. In the remaining part of the paper it is shown how the concept of a stable population can be used for defining a coefficient of inertia which measures the resistance of a population to modification of its course as a consequence of changing fertility and mortality. Some formulae are established to calculate this coefficient first for an arbitrary population, and secondly for a semistable population. In this second case the formula is particularly simple. It appears as a product of three terms: the expectation of life at birth in years, the crude birth rate, and a coefficient depending on the rate of growth and for which a numerical table is easy to establish.

Numerical solution of a logistic growth model for a population with Allee effect considering fuzzy initial values and fuzzy parameters

NASA Astrophysics Data System (ADS)

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.

Population structure of giraffes is affected by management in the Great Rift Valley, Kenya

PubMed Central

2018-01-01

Giraffe populations in East Africa have declined in the past thirty years yet there has been limited research on this species. This study had four objectives: i) to provide a baseline population assessment for the two largest populations of Rothschild’s giraffes in Kenya, ii) to assess whether there are differences in population structure between the two enclosed populations, iii) to assess the potential and possible implications of different management practices on enclosed giraffe populations to inform future decision-making, and iv) to add to the availability of information available about giraffes in the wild. I used individual identification to assess the size and structure of the two populations; in Soysambu Conservancy between May 2010 and January 2011, I identified 77 giraffes; in Lake Nakuru National Park between May 2011 and January 2012, I identified 89. Population structure differed significantly between the two sites; Soysambu Conservancy contained a high percentage of juveniles (34%) and subadults (29%) compared to Lake Nakuru NP, which contained fewer juveniles (5%) and subadults (15%). During the time of this study Soysambu Conservancy contained no lions while Lake Nakuru NP contained a high density of lions (30 lions per 100km2). Lions are the main predator of giraffes, and preferential predation on juvenile giraffes has previously been identified in Lake Nakuru NP. My results suggest that high lion density in Lake Nakuru NP may have influenced the structure of the giraffe population by removing juveniles and, consequently, may affect future population growth. I suggest that wildlife managers consider lion densities alongside breeding plans for Endangered species, since the presence of lions appears to influence the population structure of giraffes in enclosed habitats. PMID:29298338

Population structure of giraffes is affected by management in the Great Rift Valley, Kenya.

PubMed

Muller, Zoe

2018-01-01

Giraffe populations in East Africa have declined in the past thirty years yet there has been limited research on this species. This study had four objectives: i) to provide a baseline population assessment for the two largest populations of Rothschild's giraffes in Kenya, ii) to assess whether there are differences in population structure between the two enclosed populations, iii) to assess the potential and possible implications of different management practices on enclosed giraffe populations to inform future decision-making, and iv) to add to the availability of information available about giraffes in the wild. I used individual identification to assess the size and structure of the two populations; in Soysambu Conservancy between May 2010 and January 2011, I identified 77 giraffes; in Lake Nakuru National Park between May 2011 and January 2012, I identified 89. Population structure differed significantly between the two sites; Soysambu Conservancy contained a high percentage of juveniles (34%) and subadults (29%) compared to Lake Nakuru NP, which contained fewer juveniles (5%) and subadults (15%). During the time of this study Soysambu Conservancy contained no lions while Lake Nakuru NP contained a high density of lions (30 lions per 100km2). Lions are the main predator of giraffes, and preferential predation on juvenile giraffes has previously been identified in Lake Nakuru NP. My results suggest that high lion density in Lake Nakuru NP may have influenced the structure of the giraffe population by removing juveniles and, consequently, may affect future population growth. I suggest that wildlife managers consider lion densities alongside breeding plans for Endangered species, since the presence of lions appears to influence the population structure of giraffes in enclosed habitats.

A Role for M-Matrices in Modelling Population Growth

ERIC Educational Resources Information Center

James, Glyn; Rumchev, Ventsi

2006-01-01

Adopting a discrete-time cohort-type model to represent the dynamics of a population, the problem of achieving a desired total size of the population under a balanced growth (contraction) and the problem of maintaining the desired size, once achieved, are studied. Properties of positive-time systems and M-matrices are used to develop the results,…

[The decline in population growth, income distribution, and economic recession].

PubMed

Banguero, H

1983-05-01

This work uses Keynesian principles and an analysis of the Colombian population in the 1970s to argue that the Colombian policy of slowing population growth, which was adopted with the aim of improving the general welfare of the population, has had shortterm negative effects on effective demand and thus on the level of employment and welfare. These negative effects were caused by the inflexibility of income distribution, which prevented expansion of the internal market, complicated by the stagnant condition of the external sector and the budget deficit. The results of the Colombian case study demonstrate how the deceleration of population growth beginning in the 1960s had a significant impact on the levels of consumption and savings and on the patterns of consumption, leading to low levels of investment and little dynamism. Although the current Colombian economic recession is aggravated by contextual factors such as the world economic recession, the high cost of capital, the industrial recession, and declining food production among others, at the core of the crisis are longer term structural determinants such as the decline in the rate of population growth and the highly unequal distribution of income and wealth, which have contributed to a shrinking of the internal market for some types of goods. Given the unlikelihood of renewed rapid population growth, the Keynesian model suggests that the only alternative for increasing aggregate demand is state intervention through public spending and investment and reorientation of the financial system to achieve a dynamic redistribution of income. Based on these findings and on proposals of other analysts, a stragegy for revitalization is proposed which would imply a gradual income redistribution to allow increased consumption of mass produced goods by the low income groups. Direct consumption subsidies would be avoided because of their inflationary and import-expanding tendencies; rather, incentives and support would be

Development and population growth: the Indian experience.

PubMed

Chandna, R C

1996-01-01

This paper analyzes the prevailing demographic trends and development processes in India. Data were taken from the World Development Report and the Human Development Reports of South Asia and India, Census of India, and Government of India's Economic Survey. A much slower economic progress and human development was observed in South Asia as compared to those in East Asia. At present, the income levels in East Asia are 27 times higher and have a human development index twice that of South Asia. India had a better economic performance as compared to other countries in South Asia. However, the human deprivations within India continue to hinder the country's emergence as a politico-economic power on the international scene. Investigation of the diversity in population growth and development in India was presented in this paper using indicators such as: average annual population growth; couple protection rate; female literacy; mean age at marriage for females; infrastructural facilities; proportion below poverty line; and the per capita income. Finally, specific suggestions on how to accelerate the fertility transition in the country were enumerated.

Spaceflight and age affect tibial epiphyseal growth plate histomorphometry

NASA Technical Reports Server (NTRS)

Montufar-Solis, Dina; Duke, Pauline J.; Durnova, G.

1992-01-01

Growth plate histomorphometry of rats flown aboard the Soviet biosatellite Cosmos 2044, a 14-day spaceflight, was compared with that of control groups. In growth plates of flight animals, there was a significant increase in cell number per column and height of the proliferative zone and a reduction in height and cell number in the hypertrophy/calcification zone. No significant differences were found in matrix organization at the ultrastructural level of flight animals, indicating that although spacefligfht continues to affect bone growth of 15-wk-old rats, extracellular matrix is not altered in the same manner as seen previously in younger animals. All groups showed growth plate characteristics attributed to aging: lack of calcification zone, reduced hypertrophy zone, and unraveling of collagen fibrils. Tail-suspended controls did not differ from other controls in any of the parameters measured. The results suggest that growth plates of older rats are less responsive to unloading by spaceflight or suspension than those of younger rats and provide new evidence about the modifying effect of spaceflight on the growth plate.

Population Growth Rate: Teaching Guide. Measures of Progress Poster Kit Number 2.

ERIC Educational Resources Information Center

World Bank, Washington, DC.

This teaching guide accompanies the Population Growth Rate poster kit which is designed to teach students about population growth differences between rich and poor nations and about what people in developing countries are doing to help improve their quality of life. The guide is designed for use with: (1) a poster map of the world providing social…

Human population and atmospheric carbon dioxide growth dynamics: Diagnostics for the future

NASA Astrophysics Data System (ADS)

Hüsler, A. D.; Sornette, D.

2014-10-01

We analyze the growth rates of human population and of atmospheric carbon dioxide by comparing the relative merits of two benchmark models, the exponential law and the finite-time-singular (FTS) power law. The later results from positive feedbacks, either direct or mediated by other dynamical variables, as shown in our presentation of a simple endogenous macroeconomic dynamical growth model describing the growth dynamics of coupled processes involving human population (labor in economic terms), capital and technology (proxies by CO2 emissions). Human population in the context of our energy intensive economies constitutes arguably the most important underlying driving variable of the content of carbon dioxide in the atmosphere. Using some of the best databases available, we perform empirical analyses confirming that the human population on Earth has been growing super-exponentially until the mid-1960s, followed by a decelerated sub-exponential growth, with a tendency to plateau at just an exponential growth in the last decade with an average growth rate of 1.0% per year. In contrast, we find that the content of carbon dioxide in the atmosphere has continued to accelerate super-exponentially until 1990, with a transition to a progressive deceleration since then, with an average growth rate of approximately 2% per year in the last decade. To go back to CO2 atmosphere contents equal to or smaller than the level of 1990 as has been the broadly advertised goals of international treaties since 1990 requires herculean changes: from a dynamical point of view, the approximately exponential growth must not only turn to negative acceleration but also negative velocity to reverse the trend.

THE INFLUENCE OF MODEL TIME STEP ON THE RELATIVE SENSITIVITY OF POPULATION GROWTH TO SURVIVAL, GROWTH AND REPRODUCTION

EPA Science Inventory

Matrix population models are often used to extrapolate from life stage-specific stressor effects on survival and reproduction to population-level effects. Demographic elasticity analysis of a matrix model allows an evaluation of the relative sensitivity of population growth rate ...

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

USGS Publications Warehouse

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.

FACTORS ADVERSELY AFFECTING AMPHIBIAN POPULATIONS IN THE US

EPA Science Inventory

Factors known or suspected to be adversely affecting native amphibian populations in the US were identified using information from species accounts written in a standardized format by multiple authors in a forthcoming book. Specific adverse factors were identified for 53 (58%) of...

Removal of the local geomagnetic field affects reproductive growth in Arabidopsis.

PubMed

Xu, Chunxiao; Wei, Shufeng; Lu, Yan; Zhang, Yuxia; Chen, Chuanfang; Song, Tao

2013-09-01

The influence of the geomagnetic field-removed environment on Arabidopsis growth was investigated by cultivation of the plants in a near-null magnetic field and local geomagnetic field (45 µT) for the whole growth period under laboratory conditions. The biomass accumulation of plants in the near-null magnetic field was significantly suppressed at the time when plants were switching from vegetative growth to reproductive growth compared with that of plants grown in the local geomagnetic field, which was caused by a delay in the flowering of plants in the near-null magnetic field. At the early or later growth stage, no significant difference was shown in the biomass accumulation between the plants in the near-null magnetic field and local geomagnetic field. The average number of siliques and the production of seeds per plant in the near-null magnetic field was significantly lower by about 22% and 19%, respectively, than those of control plants. These resulted in a significant reduction of about 20% in the harvest index of plants in the near-null magnetic field compared with that of the controls. These results suggest that the removal of the local geomagnetic field negatively affects the reproductive growth of Arabidopsis, which thus affects the yield and harvest index. Copyright © 2013 Wiley Periodicals, Inc.

Sustainability of population growth: a case study of urban settlements in Israel.

PubMed

Portnov, B A; Pearlmutter, D

1997-01-01

"One of the most sensitive criteria for gauging the degree of socio-economic prosperity of an urban settlement is the ability to sustain stable rates of population growth by attracting newcomers and retaining existing population. The present paper argues that after reaching a particular size (on the average, 20-30,000 residents), urban localities in Israel tend to experience substantial changes in components of their annual population growth. Starting with this inflection point, the growth of settlements gradually becomes less dependent on natural causes (birth and death rates) than on the ability to attract newcomers and retain current residents. On the basis of this conclusion, a strategy of ¿redirecting priorities' to developing the peripheral regions of the country is suggested." excerpt

Drosophila melanogaster Natural Variation Affects Growth Dynamics of Infecting Listeria monocytogenes

PubMed Central

Hotson, Alejandra Guzmán; Schneider, David S.

2015-01-01

We find that in a Listeria monocytogenes/Drosophila melanogaster infection model, L. monocytogenes grows according to logistic kinetics, which means we can measure both a maximal growth rate and growth plateau for the microbe. Genetic variation of the host affects both of the pathogen growth parameters, and they can vary independently. Because growth rates and ceilings both correlate with host survival, both properties could drive evolution of the host. We find that growth rates and ceilings are sensitive to the initial infectious dose in a host genotype–dependent manner, implying that experimental results differ as we change the original challenge dose within a single strain of host. PMID:26438294

Factors affecting the accuracy of genomic selection for growth and wood quality traits in an advanced-breeding population of black spruce (Picea mariana).

PubMed

Lenz, Patrick R N; Beaulieu, Jean; Mansfield, Shawn D; Clément, Sébastien; Desponts, Mireille; Bousquet, Jean

2017-04-28

Genomic selection (GS) uses information from genomic signatures consisting of thousands of genetic markers to predict complex traits. As such, GS represents a promising approach to accelerate tree breeding, which is especially relevant for the genetic improvement of boreal conifers characterized by long breeding cycles. In the present study, we tested GS in an advanced-breeding population of the boreal black spruce (Picea mariana [Mill.] BSP) for growth and wood quality traits, and concurrently examined factors affecting GS model accuracy. The study relied on 734 25-year-old trees belonging to 34 full-sib families derived from 27 parents and that were established on two contrasting sites. Genomic profiles were obtained from 4993 Single Nucleotide Polymorphisms (SNPs) representative of as many gene loci distributed among the 12 linkage groups common to spruce. GS models were obtained for four growth and wood traits. Validation using independent sets of trees showed that GS model accuracy was high, related to trait heritability and equivalent to that of conventional pedigree-based models. In forward selection, gains per unit of time were three times higher with the GS approach than with conventional selection. In addition, models were also accurate across sites, indicating little genotype-by-environment interaction in the area investigated. Using information from half-sibs instead of full-sibs led to a significant reduction in model accuracy, indicating that the inclusion of relatedness in the model contributed to its higher accuracies. About 500 to 1000 markers were sufficient to obtain GS model accuracy almost equivalent to that obtained with all markers, whether they were well spread across the genome or from a single linkage group, further confirming the implication of relatedness and potential long-range linkage disequilibrium (LD) in the high accuracy estimates obtained. Only slightly higher model accuracy was obtained when using marker subsets that were

Population Growth and Global Security: Toward an American Strategic Commitment.

ERIC Educational Resources Information Center

Mumford, Steven

1981-01-01

Addresses the world population problem by highlighting three crucial areas: the relationship between population growth control and national security issues, the role of American leadership in resolving the problem, and the barriers to effective action. One barrier discussed in detail is the Roman Catholic Church's stand on abortion and…

Can coyotes affect deer populations in Southeastern North America?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kilgo, J., C.; Ray, H., Scott; Ruth, Charles

2010-07-01

ABSTRACT The coyote (Canis latrans) is a recent addition to the fauna of eastern North America, and in many areas coyote populations have been established for only a decade or two. Although coyotes are known predators of white-tailed deer (Odocoileus virginianus) in their historic range, effects this new predator may have on eastern deer populations have received little attention. We speculated that in the southeastern United States, coyotes may be affecting deer recruitment, and we present 5 lines of evidence that suggest this possibility. First, the statewide deer population in South Carolina has declined coincident with the establishment and increasemore » in the coyote population. Second, data sets from the Savannah River Site (SRS) in South Carolina indicate a new mortality source affecting the deer population concurrent with the increase in coyotes. Third, an index of deer recruitment at SRS declined during the period of increase in coyotes. Fourth, food habits data from SRS indicate that fawns are an important food item for coyotes during summer. Finally, recent research from Alabama documented significant coyote predation on fawns there. Although this evidence does not establish cause and effect between coyotes and observed declines in deer recruitment, we argue that additional research should proactively address this topic in the region. We identified several important questions on the nature of the deer–coyote relationship in the East.« less

Urban Ecology: Patterns of Population Growth and Ecological Effects

Treesearch

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...

Urban growth in Korea, 1970-1980: an application of the human ecological perspective.

PubMed

Ko, S H

1994-07-01

This study supports the ecological perspective proposed by Duncan (population, environment, organization, and technology) explaining urban population growth. Data were obtained from the 1970 and 1980 Korean Population Census and Korean Municipal Yearbook on cities with a minimum size of 20,000-50,000 people (108 cities and towns). Urban growth is most strongly influenced by indigenous labor surplus and the population potential of the city to be in contact with another city. Nine multiple regression variables explained just under 66% of the variance in urban growth. Net migration was influential among those aged 15-24 years. The extent of differentiation of industry affected net migration only among those aged 15-24 years and those aged 35-44 years. Population redistribution was more affected directly by changes in industrial organization, and migration was affected indirectly by environmental and technological effects on organization. Urban growth through migration of older age groups was affected by government expenditure on public works. Urban growth was not much affected by transportation/communication concentration, manufacturing concentration, urban labor surplus, population size, and site. Urban growth was viewed as the interaction between the unemployment rate and the urban wage, following Todaro's equilibrium models. In Korea, larger cities only grew faster during the 1960s. By the 1970s, upper middle-sized cities grew faster. Location was not a significant factor in explaining urban growth, but growth was rapid along a corridor within 100 km from Seoul and 50 km from Pusan, the second largest city in Korea. Caution was urged in interpreting Korea's ecological urban growth patterns as indicative of developing countries.

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

NASA Astrophysics Data System (ADS)

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.

Auditory processing deficits in growth restricted fetuses affect later language development.

PubMed

Kisilevsky, Barbara S; Davies, Gregory A L

2007-01-01

An increased risk for language deficits in infants born growth restricted has been reported in follow-up studies for more than 20 years, suggesting a relation between fetal auditory system development and later language learning. Work with animal models indicate that there are at least two ways in which growth restriction could affect the development of auditory perception in human fetuses: a delay in myelination or conduction and an increase in sensorineural threshold. Systematic study of auditory function in growth restricted human fetuses has not been reported. However, results of studies employing low-risk fetuses delivering as healthy full-term infants demonstrate that, by late gestation, the fetus can hear, sound properties modulate behavior, and sensory information is available from both inside (e.g., maternal vascular) and outside (e.g., noise, voices, music) of the maternal body. These data provide substantive evidence that the auditory system is functioning and that environmental sounds are available for shaping neural networks and laying the foundation for language acquisition before birth. We hypothesize that fetal growth restriction affects auditory system development, resulting in atypical auditory information processing in growth restricted fetuses compared to healthy, appropriately-grown-for-gestational-age fetuses. Speech perception that lays the foundation for later language competence will differ in growth restricted compared to normally grown fetuses and be associated with later language abilities.

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

USGS Publications Warehouse

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.

Growth, reproduction & population structure of the freshwater crab Sinopotamon yangtsekiense bott, 1967, from Zhejiang, China

NASA Astrophysics Data System (ADS)

Chen, Tao; Lai, Wei; Du, Nan-Shan

1994-03-01

Monthly investigations were mae on the population of Chinese freshwater crab, Sinopotamon yangtsekiense Bott, 1967 from April, 1984 to March, 1985. The data on 4413 specimens show that the growth was affected mainly by temperature. During the April to November growth period, the crabs' major development occurred from June through October. One year was required for a fine white oocyte to develop into a mature egg. The reproduction period was June October. Females bearing eggs were taken from June August, and crabs with young were found from July October. The females reproduced once a year but could for more than one year. The number of eggs carried by a female varied greatly according to the size of the crab, ranging from 30 to 100 eggs. New-born crabs become mature after 1 2 years. The sex ratio was approximately 1∶1 in the overall population. However, the larger crabs are predominantly male. The age distribution of S. yangtsekinese was estimated from size frequency histograms. There were more adult crabs (over 70%) from June to October and more immature crabs (over 50%) from November to May.

Modeling the growth of individuals in plant populations: local density variation in a strand population of Xanthium strumarium (Asteraceae).

PubMed

Weiner, J; Kinsman, S; Williams, S

1998-11-01

We studied the growth of individual Xanthium strumarium plants growing at four naturally occurring local densities on a beach in Maine: (1) isolated plants, (2) pairs of plants ≤1 cm apart, (3) four plants within 4 cm of each other, and (4) discrete dense clumps of 10-39 plants. A combination of nondestructive measurements every 2 wk and parallel calibration harvests provided very good estimates of the growth in aboveground biomass of over 400 individual plants over 8 wk and afforded the opportunity to fit explicit growth models to 293 of them. There was large individual variation in growth and resultant size within the population and within all densities. Local crowding played a role in determining plant size within the population: there were significant differences in final size between all densities except pairs and quadruples, which were almost identical. Overall, plants growing at higher densities were more variable in growth and final size than plants growing at lower densities, but this was due to increased variation among groups (greater variation in local density and/or greater environmental heterogeneity), not to increased variation within groups. Thus, there was no evidence of size asymmetric competition in this population. The growth of most plants was close to exponential over the study period, but half the plants were slightly better fit by a sigmoidal (logistic) model. The proportion of plants better fit by the logistic model increased with density and with initial plant size. The use of explicit growth models over several growth intervals to describe stand development can provide more biological content and more statistical power than "growth-size" methods that analyze growth intervals separately.

Consequences of increased longevity for wealth, fertility, and population growth

NASA Astrophysics Data System (ADS)

Bogojević, A.; Balaž, A.; Karapandža, R.

2008-01-01

We present, solve and numerically simulate a simple model that describes the consequences of increased longevity for fertility rates, population growth and the distribution of wealth in developed societies. We look at the consequences of the repeated use of life extension techniques and show that they represent a novel commodity whose introduction will profoundly influence key aspects of the economy and society in general. In particular, we uncover two phases within our simplified model, labeled as ‘mortal’ and ‘immortal’. Within the life extension scenario it is possible to have sustainable economic growth in a population of stable size, as a result of dynamical equilibrium between the two phases.

Effect of Population Growths on Water Resources in Dubai Emirate, United Arab Emirates

NASA Astrophysics Data System (ADS)

Al-Nuaimi, Hind S.; Murad, Ahmed A.

The Emirate of Dubai is situated to the north of the United Arab Emirates on the Arabian Gulf. Due to its political stability and strong economy, people are continuing to immigrate to Dubai and this will enhance the stress on water resources. Therefore, demands for water will increase significantly in Dubai. The scarcity of water resources in Dubai is evident. The total production of water in the Dubai has increased to 61,478 million gallons in 2004. About 58,808 million gallons has been produced from the desalination plants in 2004. The production of freshwater from the main aquifers is about 2763 and 2655 million gallons for the years 2003 and 2004, respectively. The reduction of groundwater in 2004 may be ascribed to the low amount of rainfall and to the decreasing capacity of the aquifers. Treated wastewater is another source for water whose quantity was increased from 72 m3 to about 107 m3 in 2000 and 2004, respectively. The increase in water production in Dubai to meet the demand corresponds to population growth and this might be attributed to the political stability and strong economy. Moreover, major problems related to the water resources have appeared and affected the availability of freshwater in Dubai. These problems include: lowering water level and groundwater deterioration. This paper is aimed to assess the impacts of population growth on water resources in Dubai.

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

PubMed

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

Contributions of long-distance dispersal to population growth in colonising Pinus ponderosa populations.

PubMed

Lesser, Mark R; Jackson, Stephen T

2013-03-01

Long-distance dispersal is an integral part of plant species migration and population development. We aged and genotyped 1125 individuals in four disjunct populations of Pinus ponderosa that were initially established by long-distance dispersal in the 16th and 17th centuries. Parentage analysis was used to determine if individuals were the product of local reproductive events (two parents present), long-distance pollen dispersal (one parent present) or long-distance seed dispersal (no parents present). All individuals established in the first century at each site were the result of long-distance dispersal. Individuals reproduced at younger ages with increasing age of the overall population. These results suggest Allee effects, where populations were initially unable to expand on their own, and were dependent on long-distance dispersal to overcome a minimum-size threshold. Our results demonstrate that long-distance dispersal was not only necessary for initial colonisation but also to sustain subsequent population growth during early phases of expansion. © 2012 Blackwell Publishing Ltd/CNRS.

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

Treesearch

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...

Complex numerical responses to top-down and bottom-up processes in vertebrate populations.

PubMed Central

Sinclair, A R E; Krebs, Charles J

2002-01-01

Population growth rate is determined in all vertebrate populations by food supplies, and we postulate bottom-up control as the universal primary standard. But this primary control system can be overridden by three secondary controls: top-down processes from predators, social interactions within the species and disturbances. Different combinations of these processes affect population growth rates in different ways. Thus, some relationships between growth rate and density can be hyperbolic or even have multiple nodes. We illustrate some of these in marsupial, ungulate and rabbit populations. Complex interactions between food, predators, environmental disturbance and social behaviour produce the myriad observations of population growth in nature, and we need to develop generalizations to classify populations. Different animal groups differ in the combination of these four processes that affect them, in their growth rates and in their vulnerability to extinction. Because conservation and management of populations depend critically on what factors drive population growth, we need to develop universal generalizations that will relieve us from the need to study every single population before we can make recommendations for management. PMID:12396514

Impacts of Hispanic Population Growth on Rural Wages. Agricultural Economic Report.

ERIC Educational Resources Information Center

Newman, Constance

Although earnings generally increased in rural areas in the 1990s, Hispanic population growth led to lower wages for at least one segment of the rural population--workers with a high school degree (skilled workers), particularly men in this skill group. Using data from the Bureau of Economic Analysis and the Current Population Survey, this report…

Growth history and crown vine coverage are principal factors influencing growth and mortality rates of big-leaf mahogany Swietenia macrophylla in Brazil

Treesearch

James Grogan; R. Matthew Landis

2009-01-01

1. Current efforts to model population dynamics of high-value tropical timber species largely assume that individual growth history is unimportant to population dynamics, yet growth autocorrelation is known to adversely affect model predictions. In this study, we analyse a decade of annual census data from a natural population of big-leaf mahogany Swietenia macrophylla...

High temperature combined with drought affect rainfed spring wheat and barley in South-Eastern Russia: I. Phenology and growth

PubMed Central

Hossain, Akbar; Teixeira da Silva, Jaime A.; Lozovskaya, Marina Viacheslavovna; Zvolinsky, Vacheslav Petrovich

2012-01-01

Heat stress, when combined with drought, is one of the major limitations to food production worldwide, especially in areas that use rainfed agriculture. As the world population continues to grow, and water resources for the crop production decline and temperature increases, so the development of heat- and drought-tolerant cultivars is an issue of global concern. In this context, four barley and two wheat genotypes were evaluated in south-eastern Russia to identify heat- and drought-tolerant genotypes for future breeding programmes by identifying suitable sowing times for specific genotypes. High temperature stress, when combined with drought during late sowing, decreased the days to visible awns, days to heading and days to ripe harvest, finally negatively affecting the growth and development of plants and resulting in a lower plant population m−2, tillers plant−1, plant height and dry matter production m−2. On the other hand, low temperature in combination with early sowing increased the number of days to germination, reduced seedling stand establishment and tillering capacity, finally affecting the growth and development of the crops. Compared to overall performance and optimum sowing date, barley genotypes ‘Zernograd.770’ and ‘Nutans’, and wheat genotype ‘Line4’ performed best in both late (high temperature with drought) and early (low temperature) stress conditions. PMID:23961209

Perturbations in growth trajectory due to early diet affect age-related deterioration in performance.

PubMed

Lee, Who-Seung; Monaghan, Pat; Metcalfe, Neil B

2016-04-01

Fluctuations in early developmental conditions can cause changes in growth trajectories that subsequently affect the adult phenotype. Here, we investigated whether compensatory growth has long-term consequences for patterns of senescence.Using three-spined sticklebacks ( Gasterosteus aculeatus ), we show that a brief period of dietary manipulation in early life affected skeletal growth rate not only during the manipulation itself, but also during a subsequent compensatory phase when fish caught up in size with controls.However, this growth acceleration influenced swimming endurance and its decline over the course of the breeding season, with a faster decline in fish that had undergone faster growth compensation.Similarly, accelerated growth led to a more pronounced reduction in the breeding period (as indicated by the duration of sexual ornamentation) over the following two breeding seasons, suggesting faster reproductive senescence. Parallel experiments showed a heightened effect of accelerated growth on these age-related declines in performance if the fish were under greater time stress to complete their compensation prior to the breeding season.Compensatory growth led to a reduction in median life span of 12% compared to steadily growing controls. While life span was independent of the eventual adult size attained, it was negatively correlated with the age-related decline in swimming endurance and sexual ornamentation.These results, complementary to those found when growth trajectories were altered by temperature rather than dietary manipulations, show that the costs of accelerated growth can last well beyond the time over which growth rates differ and are affected by the time available until an approaching life-history event such as reproduction.

The Educational Effects of Rapid Rural Population Growth.

ERIC Educational Resources Information Center

Ross, Peggy J.; Green, Bernal L.

Rapid population growth in rural areas has confronted rural communities and particularly rural educational systems with a number of problems. Sudden, large increases in students crowd school facilities and strain budgets. The different values, attitudes, and orientations toward education of the newcomers act as a catalyst for changes and can cause…

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

USGS Publications Warehouse

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.

The Long-Term Relationship between Population Growth and Vegetation Cover: An Empirical Analysis Based on the Panel Data of 21 Cities in Guangdong Province, China

PubMed Central

Li, Chao; Kuang, Yaoqiu; Huang, Ningsheng; Zhang, Chao

2013-01-01

It is generally believed that there is an inverse relationship between population growth and vegetation cover. However, reports about vegetation protection and reforestation around the World have been continuously increasing in recent decades, which seems to indicate that this relationship may not be true. In this paper, we have taken 21 cities in Guangdong Province, China as the study area to test the long-term relationship between population growth and vegetation cover, using an AVHRR NDVI data set and the panel cointegrated regression method. The results show that there is a long-term inverted N-shaped curve relationship between population growth and vegetation cover in the region where there are frequent human activities and the influence of climate change on vegetation cover changes is relatively small. The two turning points of the inverted N-shaped curve for the case of Guangdong Province correspond to 2,200 persons·km−2 and 3,820 persons·km−2, and they can provide a reference range for similar regions of the World. It also states that the population urbanization may have a negative impact on the vegetation cover at the early stage, but have a positive impact at the later stage. In addition, the Panel Error Correction Model (PECM) is used to investigate the causality direction between population growth and vegetation cover. The results show that not only will the consuming destruction effect and planting construction effect induced by the population growth have a great impact on vegetation cover changes, but vegetation cover changes in turn will also affect the population growth in the long term. PMID:23435589

Impact of Rainfall, Land-Cover and Population Growth on Groundwater - A Case Study From Karnataka State, India

NASA Astrophysics Data System (ADS)

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.

Evidence of sustained populations of a small reef fish on artificial structures. Does depth affect production on artificial reefs?

PubMed

Fowler, A M; Booth, D J

2012-03-01

The length frequencies and age structures of resident Pseudanthias rubrizonatus (n = 407), a small protogynous serranid, were measured at four isolated artificial structures on the continental shelf of north-western Australia between June and August 2008, to determine whether these structures supported full (complete size and age-structured) populations of this species. The artificial structures were located in depths between 82 and 135 m, and growth rates of juveniles and adults, and body condition of adults, were compared among structures to determine the effect of depth on potential production. All life-history stages, including recently settled juveniles, females and terminal males, of P. rubrizonatus were caught, ranging in standard length (L(s)) from 16·9 to 96·5 mm. Presumed ages estimated from whole and sectioned otoliths ranged between 22 days and 5 years, and parameter ±s.e. estimates of the von Bertalanffy growth model were L(∞) = 152 ± 34 mm, k = 0·15(±0·05) and t(0) = -1·15(±0·15). Estimated annual growth rates were similar between shallow and deep artificial structures; however, otolith lengths and recent growth of juveniles differed among individual structures, irrespective of depth. The artificial structures therefore sustained full populations of P. rubrizonatus, from recently settled juveniles through to adults; however, confirmation of the maximum age attainable for the species is required from natural populations. Depth placement of artificial reefs may not affect the production of fish species with naturally wide depth ranges. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Age, growth, and mortality of introduced flathead catfish in Atlantic rivers and a review of other populations

USGS Publications Warehouse

Kwak, T.J.; Pine, William E.; Waters, D.S.

2006-01-01

Knowledge of individual growth and mortality rates of an introduced fish population is required to determine the success and degree of establishment as well as to predict the fish's impact on native fauna. The age and growth of flathead catfish Pylodictis olivaris have been studied extensively in the species' native and introduced ranges, and estimates have varied widely. We quantified individual growth rates and age structure of three introduced flathead catfish populations in North Carolina's Atlantic slope rivers using sagittal otoliths, determined trends in growth rates over time, compared these estimates among rivers in native and introduced ranges, and determined total mortality rates for each population. Growth was significantly faster in the Northeast Cape Fear River (NECFR) than in the Lumber and Neuse rivers. Fish in the NECFR grew to a total length of 700 mm by age 7, whereas fish in the Neuse and Lumber river populations reached this length by 8 and 10 years, respectively. The growth rates of fish in all three rivers were consistently higher than those of native riverine populations, similar to those of native reservoir populations, and slower than those of other introduced riverine populations. In general, recent cohorts (1998-2001 year-classes) in these three rivers exhibited slower growth among all ages than did cohorts previous to the 1998 year-class. The annual total mortality rate was similar among the three rivers, ranging from 0.16 to 0.20. These mortality estimates are considerably lower than those from the Missouri and Mississippi rivers, suggesting relatively low fishing mortality for these introduced populations. Overall, flathead catfish populations in reservoirs grow faster than those in rivers, the growth rates of introduced populations exceed those of native populations, and eastern United States populations grow faster than those in western states. Such trends constitute critical information for understanding and managing local

Effects of Ambient Temperature on Growth Performance, Blood Metabolites, and Immune Cell Populations in Korean Cattle Steers.

PubMed

Kang, H J; Lee, I K; Piao, M Y; Gu, M J; Yun, C H; Kim, H J; Kim, K H; Baik, M

2016-03-01

Exposure to cold may affect growth performance in accordance with the metabolic and immunological activities of animals. We evaluated whether ambient temperature affects growth performance, blood metabolites, and immune cell populations in Korean cattle. Eighteen Korean cattle steers with a mean age of 10 months and a mean weight of 277 kg were used. All steers were fed a growing stage-concentrate diet at a rate of 1.5% of body weight and Timothy hay ad libitum for 8 weeks. Experimental period 1 (P1) was for four weeks from March 7 to April 3 and period 2 (P2) was four weeks from April 4 to May 1. Mean (8.7°C) and minimum (1.0°C) indoor ambient temperatures during P1 were lower (p<0.001) than those (13.0°C and 6.2°C, respectively) during P2. Daily dry matter feed intake in both the concentrate diet and forage groups was higher (p<0.001) during P2 than P1. Average daily weight gain was higher (p<0.001) during P2 (1.38 kg/d) than P1 (1.13 kg/d). Feed efficiency during P2 was higher (p = 0.015) than P1. Blood was collected three times; on March 7, April 4, and May 2. Nonesterified fatty acids (NEFA) were higher on March 7 than April 4 and May 2. Blood cortisol, glucose, and triglyceride concentrations did not differ among months. Blood CD4+, CD8+, and CD4+CD25+ T cell percentages were higher, while CD8+CD25+ T cell percentage was lower, during the colder month of March than during May, suggesting that ambient temperature affects blood T cell populations. In conclusion, colder ambient temperature decreased growth and feed efficiency in Korean cattle steers. The higher circulating NEFA concentrations observed in March compared to April suggest that lipolysis may occur at colder ambient temperatures to generate heat and maintain body temperature, resulting in lower feed efficiency in March.

Congenital heart disease affects cerebral size but not brain growth.

PubMed

Ortinau, Cynthia; Inder, Terrie; Lambeth, Jennifer; Wallendorf, Michael; Finucane, Kirsten; Beca, John

2012-10-01

Infants with congenital heart disease (CHD) have delayed brain maturation and alterations in brain volume. Brain metrics is a simple measurement technique that can be used to evaluate brain growth. This study used brain metrics to test the hypothesis that alterations in brain size persist at 3 months of age and that infants with CHD have slower rates of brain growth than control infants. Fifty-seven infants with CHD underwent serial brain magnetic resonance imaging (MRI). To evaluate brain growth across the first 3 months of life, brain metrics were undertaken using 19 tissue and fluid spaces shown on MRIs performed before surgery and again at 3 months of age. Before surgery, infants with CHD have smaller frontal, parietal, cerebellar, and brain stem measures (p < 0.001). At 3 months of age, alterations persisted in all measures except the cerebellum. There was no difference between control and CHD infants in brain growth. However, the cerebellum trended toward greater growth in infants with CHD. Somatic growth was the primary factor that related to brain growth. Presence of focal white matter lesions before and after surgery did not relate to alterations in brain size or growth. Although infants with CHD have persistent alterations in brain size at 3 months of age, rates of brain growth are similar to that of healthy term infants. Somatic growth was the primary predictor of brain growth, emphasizing the importance of optimal weight gain in this population.

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

USGS Publications Warehouse

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 (<30 animals) or remain at <100 individuals. We studied the fecundity and survivorship of three increasing, and three declining and suspected diseased, populations of bighorn sheep (the latter were subjected to outbreaks of bronchopneumonia) located in or near several large national parks in the western United States from 1991 to 1996. Titers verified both population categories were exposed to the bacteria Pasteurella haemolytica serotypes 3; 4; and 3, 4, 10; 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

Sweden Faces Zero Population Growth. Population Bulletin, Vol. 35, No. 2, June, 1980.

ERIC Educational Resources Information Center

Gendell, Murray

This bulletin examines the causes of the fertility decline in Sweden and the concerns and ambivalence of Swedes about zero population growth (ZPG). The fertility decline is attributed to many causes. In recent years there has been a drop in marriage rates and a sharp increase in non-marital cohabitation. The decline is also related to the…

Uncertainty in Population Growth Rates: Determining Confidence Intervals from Point Estimates of Parameters

PubMed Central

Devenish Nelson, Eleanor S.; Harris, Stephen; Soulsbury, Carl D.; Richards, Shane A.; Stephens, Philip A.

2010-01-01

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. PMID:21049049

Population increase, economic growth, educational inequality, and income distribution: some recent evidence.

PubMed

Ram, R

1984-04-01

The relationship between population increase, economic growth, education and income inequality was examined in a cross-section study based on data from 26 developing and 2 developed countries. As other studies have noted, high population growth is associated with a less equal income distribution. A 1 percentage point reduction in the rate of population growth tends to raise the income share of the poorest 80% in the less developed world by almost 5 percentage points and is associated with a 1.7 percentage point increase in the income share of the poorest 40%. The relationship between short-run income growth and equality, on the other hand, is strong and positive. Estimates suggest that a 1 percentage point increase in the short-run rate of growth of the gross domestic product (GDP) increases the income share of the bottom 80% by about 2 percentage points and that of the poorest 40% by almost 1 percentage point. Although higher mean schooling appears to be a mild equalizer, educational inequality does not appear to have an adverse effect on income distribution. Overall, these results challenge the widely held belief that there must be a growth-equity trade-off. Moreover, they suggest that the impact of educational inequality on income distribution may be different from that observed in earlier studies, implying a need for caution in using these earlier results as a basis for educational policy development.

Analysis of the impact of population growth in Henan Province on its environment and ecosystem.

PubMed

Zhao, J

1997-01-01

"This paper analyzes the effects of population growth on the...environment and ecosystem [of China's Henan Province]. This paper also proposes a key countermeasure to deal with the population growth and environmental improvement of Henan Province." excerpt

Meteorological limits on the growth and development of screwworm populations

NASA Technical Reports Server (NTRS)

Phinney, D. E.; Arp, G. K.

1978-01-01

A program to evaluate the use of remotely sensed data as an additional tool in existing and projected efforts to eradicate the screwworm began in 1973. Estimating weather conditions by use of remotely sensed data was part of the study. Next, the effect of weather on screwworm populations was modeled. A significant portion of the variation in screwworm population growth and development has been traced to weather-related parameters. This report deals with the salient points of the weather and the screwworm population interaction.

Growth in an English population from the Industrial Revolution.

PubMed

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.

A necessary condition for dispersal driven growth of populations with discrete patch dynamics.

PubMed

Guiver, Chris; Packman, David; Townley, Stuart

2017-07-07

We revisit the question of when can dispersal-induced coupling between discrete sink populations cause overall population growth? Such a phenomenon is called dispersal driven growth and provides a simple explanation of how dispersal can allow populations to persist across discrete, spatially heterogeneous, environments even when individual patches are adverse or unfavourable. For two classes of mathematical models, one linear and one non-linear, we provide necessary conditions for dispersal driven growth in terms of the non-existence of a common linear Lyapunov function, which we describe. Our approach draws heavily upon the underlying positive dynamical systems structure. Our results apply to both discrete- and continuous-time models. The theory is illustrated with examples and both biological and mathematical conclusions are drawn. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Wolbachia Affects Reproduction and Population Dynamics of the Coffee Berry Borer (Hypothenemus hampei): Implications for Biological Control

PubMed Central

Mariño, Yobana A.; Verle Rodrigues, José C.; Bayman, Paul

2017-01-01

Wolbachia are widely distributed endosymbiotic bacteria that influence the reproduction and fitness of their hosts. In recent years the manipulation of Wolbachia infection has been considered as a potential tool for biological control. The coffee berry borer (CBB), Hypothenemus hampei, is the most devastating coffee pest worldwide. Wolbachia infection in the CBB has been reported, but until now the role of Wolbachia in CBB reproduction and fitness has not been tested. To address this issue we reared the CBB in artificial diets with and without tetracycline (0.1% w/v) for ten generations. Tetracycline reduced significantly the relative proportion of Wolbachia in the CBB microbiota from 0.49% to 0.04%. This reduction affected CBB reproduction: females fed with tetracycline had significantly fewer progeny, lower fecundity, and fewer eggs per female. Tetracycline also reduced the population growth rate (λ), net reproductive rate (R0), and mean generation time (T) in CBB; the reduction in population growth was mostly due to variation in fertility, according to life time response experiments (LTREs) analysis. Our results suggest that Wolbachia contribute to the reproductive success of the CBB and their manipulation represents a possible approach to CBB biocontrol mediated by microbiome management. PMID:28085049

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

PubMed

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

Frequency-dependent population dynamics: effect of sex ratio and mating system on the elasticity of population growth rate.

PubMed

Haridas, C V; Eager, Eric Alan; Rebarber, Richard; Tenhumberg, Brigitte

2014-11-01

When vital rates depend on population structure (e.g., relative frequencies of males or females), an important question is how the long-term population growth rate λ responds to changes in rates. For instance, availability of mates may depend on the sex ratio of the population and hence reproductive rates could be frequency-dependent. In such cases change in any vital rate alters the structure, which in turn, affect frequency-dependent rates. We show that the elasticity of λ to a rate is the sum of (i) the effect of the linear change in the rate and (ii) the effect of nonlinear changes in frequency-dependent rates. The first component is always positive and is the classical elasticity in density-independent models obtained directly from the population projection matrix. The second component can be positive or negative and is absent in density-independent models. We explicitly express each component of the elasticity as a function of vital rates, eigenvalues and eigenvectors of the population projection matrix. We apply this result to a two-sex model, where male and female fertilities depend on adult sex ratio α (ratio of females to males) and the mating system (e.g., polygyny) through a harmonic mating function. We show that the nonlinear component of elasticity to a survival rate is negligible only when the average number of mates (per male) is close to α. In a strictly monogamous species, elasticity to female survival is larger than elasticity to male survival when α<1 (less females). In a polygynous species, elasticity to female survival can be larger than that of male survival even when sex ratio is female biased. Our results show how demography and mating system together determine the response to selection on sex-specific vital rates. Copyright © 2014 Elsevier Inc. All rights reserved.

Computer Simulation of the Population Growth (Schizosaccharomyces Pombe) Experiment.

ERIC Educational Resources Information Center

Daley, Michael; Hillier, Douglas

1981-01-01

Describes a computer program (available from authors) developed to simulate "Growth of a Population (Yeast) Experiment." Students actively revise the counting techniques with realistically simulated haemocytometer or eye-piece grid and are reminded of the necessary dilution technique. Program can be modified to introduce such variables…

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

PubMed

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

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

NASA Astrophysics Data System (ADS)

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.

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

ERIC Educational Resources Information Center

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…

Parameter Stability of the Functional–Structural Plant Model GREENLAB as Affected by Variation within Populations, among Seasons and among Growth Stages

PubMed Central

Ma, Yuntao; Li, Baoguo; Zhan, Zhigang; Guo, Yan; Luquet, Delphine; de Reffye, Philippe; Dingkuhn, Michael

2007-01-01

Background and Aims It is increasingly accepted that crop models, if they are to simulate genotype-specific behaviour accurately, should simulate the morphogenetic process generating plant architecture. A functional–structural plant model, GREENLAB, was previously presented and validated for maize. The model is based on a recursive mathematical process, with parameters whose values cannot be measured directly and need to be optimized statistically. This study aims at evaluating the stability of GREENLAB parameters in response to three types of phenotype variability: (1) among individuals from a common population; (2) among populations subjected to different environments (seasons); and (3) among different development stages of the same plants. Methods Five field experiments were conducted in the course of 4 years on irrigated fields near Beijing, China. Detailed observations were conducted throughout the seasons on the dimensions and fresh biomass of all above-ground plant organs for each metamer. Growth stage-specific target files were assembled from the data for GREENLAB parameter optimization. Optimization was conducted for specific developmental stages or the entire growth cycle, for individual plants (replicates), and for different seasons. Parameter stability was evaluated by comparing their CV with that of phenotype observation for the different sources of variability. A reduced data set was developed for easier model parameterization using one season, and validated for the four other seasons. Key Results and Conclusions The analysis of parameter stability among plants sharing the same environment and among populations grown in different environments indicated that the model explains some of the inter-seasonal variability of phenotype (parameters varied less than the phenotype itself), but not inter-plant variability (parameter and phenotype variability were similar). Parameter variability among developmental stages was small, indicating that parameter

"Peer Review: Nonroad (NR) Updates to Population Growth, Compression Ignition (CI) Criteria, Toxic Emission Factors and Speciation Profiles"

EPA Science Inventory

This report focuses on the methodology for estimating growth in NR engine populations as used in the MOVES201X-NONROAD emission inventory model. MOVES NR growth rates start with base year engine populations and estimate growth in the populations of NR engines, while applying cons...

Basic Fibroblast Growth Factor Influences Epidermal Homeostasis of Living Skin Equivalents through Affecting Fibroblast Phenotypes and Functions.

PubMed

Yang, Lujun; Zhang, Dangui; Wu, Hongjuan; Xie, Sitian; Zhang, Mingjun; Zhang, Bingna; Tang, Shijie

2018-05-30

To elucidate the possible mechanisms of how basic fibroblast growth factor (bFGF) influences epidermal homeostasis in a living skin equivalent (LSE) model. Several wound healing-related growth factors were analyzed at protein and mRNA levels for dermal fibroblasts of induced alpha-smooth muscle actin (α-SMA)-positive or α-SMA-negative phenotypes. During culturing an LSE model by seeding normal human keratinocytes on a fibroblast-populated type I collagen gel, bFGF or neutralizing antibody for keratinocyte growth factor (KGF) was added to investigate its effects on fibroblast phenotypes and, subsequently, epidermal homeostasis by histology and immunohistochemistry. The α-SMA-positive phenotype of fibroblasts induced by transforming growth factor beta-1 (TGF-β1) markedly suppressed the expression of KGF and hepatocyte growth factor (HGF), and slightly upregulated vascular endothelial growth factor (VEGF) and TGF-β1 at mRNA and protein levels, compared with α-SMA-negative fibroblasts treated with bFGF. α-SMA expression of fibroblasts at the epidermal-mesenchymal junction of the LSEs was suppressed by the addition of bFGF, and a better-differentiated epidermis was presented. The abrogation of KGF from fibroblasts by the addition of the KGF neutralizing antibody disenabled the LSE culturing system to develop an epidermis. bFGF, through affecting the phenotypes and functions of fibroblasts, especially KGF expression, influenced epidermal homeostasis in an LSE model. © 2018 S. Karger AG, Basel.

Plantation Spacing Affects Early Growth of Planted Virginia Pine

Treesearch

T.E. Russell

1979-01-01

Spacings ranging from 4 x 4 to 8 x 8 ft did not affect 15 year height growth of Virginia pines planted on a cutover Cumberland Plateau site. Wider spacings produced trees of larger diameters than did closer spacings; closer spacings had more basal area and volume. Although height to the base of the live crown increased as spacing narrowed, self-pruning was poor at all...

An SNP in the MyoD1 gene intron 2 associated with growth and carcass traits in three duck populations.

PubMed

Wu, Y; Pi, J S; Pan, A L; Pu, Y J; Du, J P; Shen, J; Liang, Z H; Zhang, J R

2012-12-01

Myogenic differentiation 1 (MyoD1) genes belong to the MyoD gene family and play key roles in growth and muscle development. This study was designed to investigate the effects of variants in the MyoD1 gene on duck growth and carcass traits. Three duck populations (Cherry Valley, Jingjiang, and Muscovy) were sampled, their growth and carcass traits were measured, and they were genotyped using the PCR-RFLP method. The results showed one novel polymorphism, an alteration in intron 2 of the MyoD1 gene (A to T). It was associated with the traits of weight at 8 weeks, carcass weight, breast muscle weight, leg muscle weight, eviscerated percentage, percentage of leg muscle weight, dressing percentage, and lean meat percentage. This alteration in intron 2 of MyoD1 may be linked with potential major loci or genes affecting some growth and carcass traits.

Recommendations for the Use of ICT in Elderly Populations with Affective Disorders

PubMed Central

Gros, Auriane; Bensamoun, David; Manera, Valeria; Fabre, Roxane; Zacconi-Cauvin, Anne-Marie; Thummler, Susanne; Benoit, Michel; Robert, Philippe; David, Renaud

2016-01-01

Objective: Affective disorders are frequently encountered among elderly populations, and the use of information and communication technologies (ICT) could provide an added value for their recognition and assessment in addition to current clinical methods. The diversity and lack of consensus in the emerging field of ICTs is however a strong limitation for their global use in daily practice. The aim of the present article is to provide recommendations for the use of ICTs for the assessment and management of affective disorders among elderly populations with or without dementia. Methods: A Delphi panel was organized to gather recommendations from experts in the domain. A set of initial general questions for the use of ICT in affective disorders was used to guide the discussion of the expert panel and to analyze the Strengths, Weaknesses, Opportunities, and Threats (SWOT) of employing ICT in elderly populations with affective disorders. Based on the results collected from this first round, a web survey was sent to local general practitioners (GPs) and to all interns in psychiatry in France. Results: The results of the first round revealed that ICT may offer very useful tools for practitioners involved in the diagnosis and management of affective disorders. However, the results of the web survey showed the interest to explain better to current and upcoming practitioners the utility of ICT especially for people living with dementia. PMID:27877126

Recommendations for the Use of ICT in Elderly Populations with Affective Disorders.

PubMed

Gros, Auriane; Bensamoun, David; Manera, Valeria; Fabre, Roxane; Zacconi-Cauvin, Anne-Marie; Thummler, Susanne; Benoit, Michel; Robert, Philippe; David, Renaud

2016-01-01

Objective : Affective disorders are frequently encountered among elderly populations, and the use of information and communication technologies (ICT) could provide an added value for their recognition and assessment in addition to current clinical methods. The diversity and lack of consensus in the emerging field of ICTs is however a strong limitation for their global use in daily practice. The aim of the present article is to provide recommendations for the use of ICTs for the assessment and management of affective disorders among elderly populations with or without dementia. Methods : A Delphi panel was organized to gather recommendations from experts in the domain. A set of initial general questions for the use of ICT in affective disorders was used to guide the discussion of the expert panel and to analyze the Strengths, Weaknesses, Opportunities, and Threats (SWOT) of employing ICT in elderly populations with affective disorders. Based on the results collected from this first round, a web survey was sent to local general practitioners (GPs) and to all interns in psychiatry in France. Results : The results of the first round revealed that ICT may offer very useful tools for practitioners involved in the diagnosis and management of affective disorders. However, the results of the web survey showed the interest to explain better to current and upcoming practitioners the utility of ICT especially for people living with dementia.

Growth curves for ostriches (Struthio camelus) in a Brazilian population.

PubMed

Ramos, S B; Caetano, S L; Savegnago, R P; Nunes, B N; Ramos, A A; Munari, D P

2013-01-01

The objective of this study was to fit growth curves using nonlinear and linear functions to describe the growth of ostriches in a Brazilian population. The data set consisted of 112 animals with BW measurements from hatching to 383 d of age. Two nonlinear growth functions (Gompertz and logistic) and a third-order polynomial function were applied. The parameters for the models were estimated using the least-squares method and Gauss-Newton algorithm. The goodness-of-fit of the models was assessed using R(2) and the Akaike information criterion. The R(2) calculated for the logistic growth model was 0.945 for hens and 0.928 for cockerels and for the Gompertz growth model, 0.938 for hens and 0.924 for cockerels. The third-order polynomial fit gave R(2) of 0.938 for hens and 0.924 for cockerels. Among the Akaike information criterion calculations, the logistic growth model presented the lowest values in this study, both for hens and for cockerels. Nonlinear models are more appropriate for describing the sigmoid nature of ostrich growth.

Environmental Growth Conditions of Trichoderma spp. Affects Indole Acetic Acid Derivatives, Volatile Organic Compounds, and Plant Growth Promotion

PubMed Central

Nieto-Jacobo, Maria F.; Steyaert, Johanna M.; Salazar-Badillo, Fatima B.; Nguyen, Dianne Vi; Rostás, Michael; Braithwaite, Mark; De Souza, Jorge T.; Jimenez-Bremont, Juan F.; Ohkura, Mana; Stewart, Alison

2017-01-01

Trichoderma species are soil-borne filamentous fungi widely utilized for their many plant health benefits, such as conferring improved growth, disease resistance and abiotic stress tolerance to their hosts. Many Trichoderma species are able to produce the auxin phytohormone indole-3-acetic acid (IAA), and its production has been suggested to promote root growth. Here we show that the production of IAA is strain dependent and diverse external stimuli are associated with its production. In in vitro assays, Arabidopsis primary root length was negatively affected by the interaction with some Trichoderma strains. In soil experiments, a continuum effect on plant growth was shown and this was also strain dependent. In plate assays, some strains of Trichoderma spp. inhibited the expression of the auxin reporter gene DR5 in Arabidopsis primary roots but not secondary roots. When Trichoderma spp. and A. thaliana were physically separated, enhancement of both shoot and root biomass, increased root production and chlorophyll content were observed, which strongly suggested that volatile production by the fungus influenced the parameters analyzed. Trichoderma strains T. virens Gv29.8, T. atroviride IMI206040, T. sp. “atroviride B” LU132, and T. asperellum LU1370 were demonstrated to promote plant growth through volatile production. However, contrasting differences were observed with LU1370 which had a negative effect on plant growth in soil but a positive effect in plate assays. Altogether our results suggest that the mechanisms and molecules involved in plant growth promotion by Trichoderma spp. are multivariable and are affected by the environmental conditions. PMID:28232840

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

PubMed

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.

An assessment of bird habitat quality using population growth rates

USGS Publications Warehouse

Knutson, M.G.; Powell, L.A.; Hines, R.K.; Friberg, M.A.; Niemi, G.J.

2006-01-01

Survival and reproduction directly affect population growth rate (lambda) making lambda a fundamental parameter for assessing habitat quality. We used field data, literature review, and a computer simulation to predict annual productivity and lambda for several species of landbirds breeding in floodplain and upland forests in the Midwestern United States. We monitored 1735 nests of 27 species; 760 nests were in the uplands and 975 were in the floodplain. Each type of forest habitat (upland and floodplain) was a source habitat for some species. Despite a relatively low proportion of regional forest cover, the majority of species had stable or increasing populations in all or some habitats, including six species of conservation concern. In our search for a simple analog for lambda, we found that only adult apparent survival, juvenile survival, and annual productivity were correlated with lambda; daily nest survival and relative abundance estimated from point counts were not. Survival and annual productivity are among the most costly demographic parameters to measure and there does not seem to be a low-cost alternative. In addition, our literature search revealed that the demographic parameters needed to model annual productivity and lambda were unavailable for several species. More collective effort across North America is needed to fill the gaps in our knowledge of demographic parameters necessary to model both annual productivity and lambda. Managers can use habitat-specific predictions of annual productivity to compare habitat quality among species and habitats for purposes of evaluating management plans.

Aridity weakens population-level effects of multiple species interactions on Hibiscus meyeri.

PubMed

Louthan, Allison M; Pringle, Robert M; Goheen, Jacob R; Palmer, Todd M; Morris, William F; Doak, Daniel F

2018-01-16

Predicting how species' abundances and ranges will shift in response to climate change requires a mechanistic understanding of how multiple factors interact to limit population growth. Both abiotic stress and species interactions can limit populations and potentially set range boundaries, but we have a poor understanding of when and where each is most critical. A commonly cited hypothesis, first proposed by Darwin, posits that abiotic factors (e.g., temperature, precipitation) are stronger determinants of range boundaries in apparently abiotically stressful areas ("stress" indicates abiotic factors that reduce population growth), including desert, polar, or high-elevation environments, whereas species interactions (e.g., herbivory, competition) play a stronger role in apparently less stressful environments. We tested a core tenet of this hypothesis-that population growth rate is more strongly affected by species interactions in less stressful areas-using experimental manipulations of species interactions affecting a common herbaceous plant, Hibiscus meyeri (Malvaceae), across an aridity gradient in a semiarid African savanna. Population growth was more strongly affected by four distinct species interactions (competition with herbaceous and shrubby neighbors, herbivory, and pollination) in less stressful mesic areas than in more stressful arid sites. However, contrary to common assumptions, this effect did not arise because of greater density or diversity of interacting species in less stressful areas, but rather because aridity reduced sensitivity of population growth to these interactions. Our work supports classic predictions about the relative strength of factors regulating population growth across stress gradients, but suggests that this pattern results from a previously unappreciated mechanism that may apply to many species worldwide.

Population growth and development of Liposcelis pearmani (Psocoptera: Liposcelididae) at constant temperatures and relative humidities.

PubMed

Aminatou, B A; Gautam, S G; Opit, G P; Talley, J; Shakya, K

2011-08-01

Psocids of genus Liposcelis are now considered serious pests of stored products. We investigated the effects of eight temperatures (22.5, 25.0, 27.5, 30.0, 32.5, 35.0, 37.5, and 40.0°C) and four relative humidities (43, 55, 63, and 75%) on population growth and development of the psocid Liposcelis pearmani Lienhard. L. pearmani did not survive at 37.5 and 40.0°C, at all relative humidities tested; at 43% RH, at all temperatures tested; and at 55% RH, at 32.5 and 35°C. The greatest population growth was recorded at 32.5°C and 75% RH (32-fold growth). L. pearmani males have two to four nymphal instars, and the percentages of males with two, three, and four instars were 17, 63, and 20%, respectively. Female L. pearmani have two to five instars, and the percentages of females with two, three, four, and five instars were 5, 39, 55, and 1%, respectively. We developed temperature-dependent development equations for male and female eggs, individual nymphal, combined nymphal, and combined immature stages. Based on 30-d population growth, L. pearmani cannot survive at temperatures >35.0°C; does not thrive at low relative humidities (55%), at temperatures above 25°C; and has a high optimum relative humidity for population growth (75%). Therefore, we expect it to have a more limited distribution compared with other Liposcelis species. These data provide a better understanding of how temperature and RH may influence L. pearmani population dynamics and can be used in population growth models to help develop effective management strategies for this psocid, and to predict its occurrence.

From facilitation to competition: temperature-driven shift in dominant plant interactions affects population dynamics in seminatural grasslands.

PubMed

Olsen, Siri L; Töpper, Joachim P; Skarpaas, Olav; Vandvik, Vigdis; Klanderud, Kari

2016-05-01

Biotic interactions are often ignored in assessments of climate change impacts. However, climate-related changes in species interactions, often mediated through increased dominance of certain species or functional groups, may have important implications for how species respond to climate warming and altered precipitation patterns. We examined how a dominant plant functional group affected the population dynamics of four co-occurring forb species by experimentally removing graminoids in seminatural grasslands. Specifically, we explored how the interaction between dominants and subordinates varied with climate by replicating the removal experiment across a climate grid consisting of 12 field sites spanning broad-scale temperature and precipitation gradients in southern Norway. Biotic interactions affected population growth rates of all study species, and the net outcome of interactions between dominants and subordinates switched from facilitation to competition with increasing temperature along the temperature gradient. The impacts of competitive interactions on subordinates in the warmer sites could primarily be attributed to reduced plant survival. Whereas the response to dominant removal varied with temperature, there was no overall effect of precipitation on the balance between competition and facilitation. Our findings suggest that global warming may increase the relative importance of competitive interactions in seminatural grasslands across a wide range of precipitation levels, thereby favouring highly competitive dominant species over subordinate species. As a result, seminatural grasslands may become increasingly dependent on disturbance (i.e. traditional management such as grazing and mowing) to maintain viable populations of subordinate species and thereby biodiversity under future climates. Our study highlights the importance of population-level studies replicated under different climatic conditions for understanding the underlying mechanisms of climate

[Effect of the population density on growth and regeneration in the snail Achatina fulica].

PubMed

Sidel'nikov, A P; Stepanov, I I

2000-01-01

In the laboratory, the growth rate of the giant African snail Achatina fulica, as estimated by the weight and shell length was shown to decrease when the population density increased from 10 to 60 snails/m2 of the total terrarium area for five months. In the second experiment, when the population density increased from 48 to 193 snails/m2, the growth rate had already decreased by six weeks. In the groups with a high population density the feeding behavior was weakened, expressed by a greater amount of nonconsumed food, according to visual observations, than in the groups with lower population densities. At the population density of 10 to 60 snails/m2, the proliferative activity in the course of the optic tentacle regeneration, as expressed by the mitotic index, did not differ reliably within five months. In the second experiment, the mitotic indices at the population densities of 96 and 193 snails/m2 within 1.5 months exceeded that of 48 snails/m2. Recommendations are given concerning the population density from the viewpoint of commercial growth of the snails. It was proposed that, based on the analysis of the mechanism underlying the inhibition of feeding behavior in populations with extra high densities, one may develop a new approach to the production of chemical agents to control land snails as agricultural pests.

Growth rates and variances of unexploited wolf populations in dynamic equilibria

USGS Publications Warehouse

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).

Rural Renaissance in America? The Revival of Population Growth in Remote Areas.

ERIC Educational Resources Information Center

Morrison, Peter A.; Wheeler, Judith P.

Presenting narrative and tabular documentation of the revival of population growth in remote, rural areas and the decline of growth in urban areas, this bulletin describes the characteristics of these shifts, considers their possible causes, and suggests some of the problems and potential benefits. Specifically, this report presents the following:…

Optimal Resting-Growth Strategies of Microbial Populations in Fluctuating Environments

PubMed Central

Geisel, Nico; Vilar, Jose M. G.; Rubi, J. Miguel

2011-01-01

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. PMID:21525975

Populational Growth Models Proportional to Beta Densities with Allee Effect

NASA Astrophysics Data System (ADS)

Aleixo, Sandra M.; Rocha, J. Leonel; Pestana, Dinis D.

2009-05-01

We consider populations growth models with Allee effect, proportional to beta densities with shape parameters p and 2, where the dynamical complexity is related with the Malthusian parameter r. For p>2, these models exhibit a population dynamics with natural Allee effect. However, in the case of 1

Rate of language evolution is affected by population size

PubMed Central

Bromham, Lindell; Hua, Xia; Fitzpatrick, Thomas G.; Greenhill, Simon J.

2015-01-01

The effect of population size on patterns and rates of language evolution is controversial. Do languages with larger speaker populations change faster due to a greater capacity for innovation, or do smaller populations change faster due to more efficient diffusion of innovations? Do smaller populations suffer greater loss of language elements through founder effects or drift, or do languages with more speakers lose features due to a process of simplification? Revealing the influence of population size on the tempo and mode of language evolution not only will clarify underlying mechanisms of language change but also has practical implications for the way that language data are used to reconstruct the history of human cultures. Here, we provide, to our knowledge, the first empirical, statistically robust test of the influence of population size on rates of language evolution, controlling for the evolutionary history of the populations and formally comparing the fit of different models of language evolution. We compare rates of gain and loss of cognate words for basic vocabulary in Polynesian languages, an ideal test case with a well-defined history. We demonstrate that larger populations have higher rates of gain of new words whereas smaller populations have higher rates of word loss. These results show that demographic factors can influence rates of language evolution and that rates of gain and loss are affected differently. These findings are strikingly consistent with general predictions of evolutionary models. PMID:25646448

The Association between Natural Amenities, Rural Population Growth, and Long-Term Residents' Economic Well-Being

ERIC Educational Resources Information Center

Hunter, Lori M; Boardman, Jason D.; Saint Onge, Jarron M.

2005-01-01

Population growth in rural areas characterized by high levels of natural amenities has recently received substantial research attention. A noted concern with amenity-driven rural population growth is its potential to raise local costs-of-living while yielding only low-wage service sector employment for long-term residents. The work presented here…

Consequences of Rapid Population Growth: An Overview. World Bank Staff Working Papers No. 691 and Population and Development Series No. 16.

ERIC Educational Resources Information Center

McNicoll, Geoffrey

A systematic discussion of the consequences of rapid population growth for economics and social systems examines growth resulting from mortality decline in the absence of comparable fertility decline. Growth resulting from net migration is also considered. The background and rationale for the study are supplied in a brief introduction. Part 2…

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

ERIC Educational Resources Information Center

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.…

Population. Global Issues Education Packet.

ERIC Educational Resources Information Center

Holm, Amy E.

One of the most critical issues that faces humanity is the world population boom. The high rate of population growth can directly affect sensitive issues such as the state of the environment, economic development, health, resource uses, and consumption. Though we have achieved the capability to override many of nature's limitations, we live in a…

Individual heterogeneity and offspring sex affect the growth-reproduction trade-off in a mammal with indeterminate growth.

PubMed

Gélin, Uriel; Wilson, Michelle E; Cripps, Jemma; Coulson, Graeme; Festa-Bianchet, Marco

2016-04-01

Reproduction can lead to a trade-off with growth, particularly when individuals reproduce before completing body growth. Kangaroos have indeterminate growth and may always face this trade-off. We combined an experimental manipulation of reproductive effort and multi-year monitoring of a large sample size of marked individuals in two populations of eastern grey kangaroos to test the predictions (1) that reproduction decreases skeletal growth and mass gain and (2) that mass loss leads to reproductive failure. We also tested if sex-allocation strategies influenced these trade-offs. Experimental reproductive suppression revealed negative effects of reproduction on mass gain and leg growth from 1 year to the next. Unmanipulated females, however, showed a positive correlation between number of days lactating and leg growth over periods of 2 years and longer, suggesting that over the long term, reproductive costs were masked by individual heterogeneity in resource acquisition. Mass gain was necessary for reproductive success the subsequent year. Although mothers of daughters generally lost more mass than females nursing sons, mothers in poor condition experienced greater mass gain and arm growth if they had daughters than if they had sons. The strong links between individual mass changes and reproduction suggest that reproductive tactics are strongly resource-dependent.

Growth and competitive effects of Centaurea stoebe populations in response to simulated nitrogen deposition.

PubMed

He, Wei-Ming; Montesinos, Daniel; Thelen, Giles C; Callaway, Ragan M

2012-01-01

Increased resource availability can promote invasion by exotic plants, raising concerns over the potential effects of global increases in the deposition of nitrogen (N). It is poorly understood why increased N favors exotics over natives. Fast growth may be a general trait of good invaders and these species may have exceptional abilities to increase growth rates in response to N deposition. Additionally, invaders commonly displace locals, and thus may have inherently greater competitive abilities. The mean growth response of Centaurea stoebe to two N levels was significantly greater than that of North American (NA) species. Growth responses to N did not vary among C. stoebe populations or NA species. Without supplemental N, NA species were better competitors than C. stoebe, and C. stoebe populations varied in competitive effects. The competitive effects of C. stoebe populations increased with N whereas the competitive effects of NA species decreased, eliminating the overall competitive advantage demonstrated by NA species in soil without N added. These results suggest that simulated N deposition may enhance C. stoebe invasion through increasing its growth and relative competitive advantage, and also indicate the possibility of local adaptation in competitive effects across the introduced range of an invader.

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

PubMed

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.

Modeling the Pre-Industrial Roots of Modern Super-Exponential Population Growth

PubMed Central

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

Response of Growth and Density of a Population of Geukensia demissa to Land-Derived Nitrogen Loading, in Waquoit Bay, Massachusetts

NASA Astrophysics Data System (ADS)

Evgenidou, A.; Valiela, I.

2002-07-01

Nutrient enrichment is a widespread phenomenon affecting coastal waters, including salt marshes. As land-derived nitrogen loading in estuarine waters increases, chlorophyll concentrations in the water also increase. We hypothesized that such increases might increase growth of the food-limited population of Geukensia demissa, which is a dominant component of salt marshes. To test this, we conducted a regional scale experiment in three estuaries of Waquoit Bay, Massachusetts that receive different nitrogen loading rates. A stable isotope experiment on mussel tissues and on particulate organic matter (POM) showed that mussels within an estuary fed on POM characteristic of that estuary, demonstrating the direct linkage between POM and mussels within an estuary. In addition, we measured age-specific shell growth rates of mussel populations using two different methods: indirectly, shell growth of mussels indicated by internal shell-lines was measured by fitting the data to the von Bertalanffy equation, and directly, mussels were transplanted from one estuary to the other two, and their actual shell growth rates after 80 days were measured. Growth rates of mussels in the Waquoit Bay estuaries varied with age of the mussel, tidal elevation, and with mean concentration of chlorophyll in the water. Mussels grew best in the lower intertidal zone, at the marsh banks. Young mussels grew faster than older mussels. Growth rates increased in response to presumed greater food supply across the estuaries, only for younger mussels. The significant differences we found among the mussels from different estuaries indicate a response to higher concentrations of food particles available in estuaries subject to higher nitrogen loads.

Anthropometric growth study of the ear in a Chinese population.

PubMed

Zhao, Shichun; Li, Dianguo; Liu, Zhenzhong; Wang, Yibiao; Liu, Lei; Jiang, Duyin; Pan, Bo

2018-04-01

A large number of anthropometric studies of the auricle have been reported in different nations, but little data were available in the Chinese population. The aim of this study was to analyze growth changes in the ear by measuring the width and length of ears in a Chinese population. A total of 480 participants were enrolled and classified into 1-, 3-, 5-, 7-, 9-, 12-, 14-, and 18-year groups (half were boys and half were girls in each group). Ear length, ear width, body weight, and body length were measured and recorded; ear index was calculated according to ear length and ear width. The growth of auricle and differences between genders were analyzed. Growth of ear in relation to body height and weight and the degree of emphasis on the length and width of the auricle were also analyzed. Ear length and width increased with age. Ear length achieved its mature size in both 14-year-old males and females. Ear width reached its mature size in males at 7 years and in females at 5 years. Different trends of ear index were shown between males and females. People in this population paid more attention to the length than the width of the auricle. The data indicated that ear development followed increase in age. There were gender and ethnic difference in the development of ear. These results may have potential implications for the diagnosis of congenital malformations, syndromes, and planning of ear reconstruction surgery. Copyright © 2017 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Detecting crop population growth using chlorophyll fluorescence imaging.

PubMed

Wang, Heng; Qian, Xiangjie; Zhang, Lan; Xu, Sailong; Li, Haifeng; Xia, Xiaojian; Dai, Liankui; Xu, Liang; Yu, Jingquan; Liu, Xu

2017-12-10

For both field and greenhouse crops, it is challenging to evaluate their growth information on a large area over a long time. In this work, we developed a chlorophyll fluorescence imaging-based system for crop population growth information detection. Modular design was used to make the system provide high-intensity uniform illumination. This system can perform modulated chlorophyll fluorescence induction kinetics measurement and chlorophyll fluorescence parameter imaging over a large area of up to 45  cm×34  cm. The system can provide different lighting intensity by modulating the duty cycle of its control signal. Results of continuous monitoring of cucumbers in nitrogen deficiency show the system can reduce the judge error of crop physiological status and improve monitoring efficiency. Meanwhile, the system is promising in high throughput application scenarios.

Quantifying long-term population growth rates of threatened bull trout: challenges, lessons learned, and opportunities

USGS Publications Warehouse

Budy, Phaedra; Bowerman, Tracy; Al-Chokhachy, Robert K.; Conner, Mary; Schaller, Howard

2017-01-01

Temporal symmetry models (TSM) represent advances in the analytical application of mark–recapture data to population status assessments. For a population of char, we employed 10 years of active and passive mark–recapture data to quantify population growth rates using different data sources and analytical approaches. Estimates of adult population growth rate were 1.01 (95% confidence interval = 0.84–1.20) using a temporal symmetry model (λTSM), 0.96 (0.68–1.34) based on logistic regressions of annual snorkel data (λA), and 0.92 (0.77–1.11) from redd counts (λR). Top-performing TSMs included an increasing time trend in recruitment (f) and changes in capture probability (p). There was only a 1% chance the population decreased ≥50%, and a 10% chance it decreased ≥30% (λMCMC; based on Bayesian Markov chain Monte Carlo procedure). Size structure was stable; however, the adult population was dominated by small adults, and over the study period there was a decline in the contribution of large adults to total biomass. Juvenile condition decreased with increasing adult densities. Utilization of these different information sources provided a robust weight-of-evidence approach to identifying population status and potential mechanisms driving changes in population growth rates.

An American Laboratory: Population Growth and Environmental Quality in California.

ERIC Educational Resources Information Center

McConnell, Robert

1993-01-01

Describes the cumulative impact of rapid population growth, industrial and military activity, agriculture, and motor vehicles on California's environmental and social fabric. Discusses these problems in California as a forecast for the nation and test to consensus-based U.S. representative government. (Author/ MCO)

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

Treesearch

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...

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

USGS Publications Warehouse

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.

Rapid population growth. Effects on the social infrastructures of southern Africa.

PubMed

Smith, J D

1995-01-01

Southern Africa's high rate of population growth and widespread poverty have serious implications for the region's social infrastructure. Large increases in the school-age population have undermined efforts to improve the quality of education since all resources are directed toward expansion of availability. To achieve a teacher-pupil ratio of 1:40 at the primary level and 1:35 at the secondary level, an estimated additional 50,000 classrooms would be required. Also jeopardized by high fertility is access to health services, safe water, and sanitation. In Mozambique, for example, where only 30% of the population has access to health services, the under-five years mortality rate is 297/1000 live births and the physician-population ratio is 1:37,970. Substandard housing, homelessness, congestion, deteriorating public services, pollution, and crime dominate urban areas. The single most effective intervention to reduce population growth in Southern Africa is female education. Women without a secondary education bear an average of seven children; if 40% of women attend secondary school, this drops to three children. Thus, governments must make gender equality a central focus of development planning and ensure that women are participants in this process. Property and inheritance laws that serve to increase the economic need for early marriage should be eliminated. Public health programs, including family planning, must be expanded. Finally, women's organizations should be strengthened and urged to foster female empowerment.

Differences in Townsend's chipmunk populations between second- and old-growth forests in western Oregon

Treesearch

D.K. Rosenberg; R.G. Anthony

1993-01-01

Because Townsend's chipmunks (Tomias townsendii) may be important in maintaining natural ecosystem processes in forests in the central Oregon Cascade Range, we compared their population characteristics in young second-growth and old-growth forests. We live-trapped Townsend's chipmunks in 5 young (30-60 yr old) second-growth and 5 old-...

Women and Population Growth: Choice beyond Childbearing. Worldwatch Paper 16.

ERIC Educational Resources Information Center

Newland, Kathleen

The paper explores the relationship of women's childbearing attitudes to educational and work opportunities. Program administrators for family planning, educational programs, and national development efforts in developing countries must realize the importance of the social and cultural environment in designing programs to reduce population growth.…

Comparisons of Growth and Survival Performance Among Selected Families and Wild Populations of Fenneropenaeus chinensis

NASA Astrophysics Data System (ADS)

Luo, Kun; Kong, Jie; Meng, Xianhong; Luan, Sheng; Cao, Baoxiang; Chen, Baolong

2018-04-01

In this study, families of selected population for growth (SP_BWT), selected population for white spot syndrome virus (WSSV) resistance (SP_RW), Bohai wild population (WP_BH) and Huanghai wild population (WP_HH) of F. chinensis were constructed through artificial insemination and with the standardized procedure of larvae rearing. Growth and survival performance were studied among four populations after a 70 days common test. The results showed that the maximum least square mean of body weight was 17.50 g in SP_BWT while the minimum was 13.03 g in WP_HH. Compared with WP_BH, body weight of SP_BWT increased by 23.41% ( P < 0.01) and that of SP_RW by 12.20% ( P > 0.05). Body weights of SP_BWT and SP_RW were significantly higher than that of WP_HH, which increased by 34.31% ( P < 0.01) and 22.10% ( P < 0.05), respectively. The mean AGR of four populations was 0.19, 0.18, 0.17 and 0.16 g d-1, respectively. Coefficient of variation of body weight among four populations was high, which ranged from 32.67% to 35.25%. Such a range showed that there was the potentiality for further improvement in selected populations. Coefficient of variation of survival rate among four populations was low, varying between 3.20% and 5.90%. The difference of survival was highly significant ( P < 0.01) between SP_BWT and WP_BH, and significant ( P < 0.05) between SP_RW and WP_BH. However, no significant difference among other populations ( P < 0.05) was observed. Different growth performances were also observed among different families in each population. The body weight of 798F family was the highest. The absolute growth rate (AGR) was 0.25 g d-1, 150% higher than that of the lowest one, 0.1 g d-1 in 807F family. Survival rate of families among four populations was different. The highest was 94.74%, and the lowest was 71.88%.

Growth and Competitive Effects of Centaurea stoebe Populations in Response to Simulated Nitrogen Deposition

PubMed Central

He, Wei-Ming; Montesinos, Daniel; Thelen, Giles C.; Callaway, Ragan M.

2012-01-01

Increased resource availability can promote invasion by exotic plants, raising concerns over the potential effects of global increases in the deposition of nitrogen (N). It is poorly understood why increased N favors exotics over natives. Fast growth may be a general trait of good invaders and these species may have exceptional abilities to increase growth rates in response to N deposition. Additionally, invaders commonly displace locals, and thus may have inherently greater competitive abilities. The mean growth response of Centaurea stoebe to two N levels was significantly greater than that of North American (NA) species. Growth responses to N did not vary among C. stoebe populations or NA species. Without supplemental N, NA species were better competitors than C. stoebe, and C. stoebe populations varied in competitive effects. The competitive effects of C. stoebe populations increased with N whereas the competitive effects of NA species decreased, eliminating the overall competitive advantage demonstrated by NA species in soil without N added. These results suggest that simulated N deposition may enhance C. stoebe invasion through increasing its growth and relative competitive advantage, and also indicate the possibility of local adaptation in competitive effects across the introduced range of an invader. PMID:22563451

Population and development.

PubMed

Rao, S V

1992-01-01

A unified approach to development is recommended: one in which the social, economic, and political components are accounted for within a multidimensional process of reorganization and reorientation of structures and attitudes, customs, and beliefs. During the 1970s, development was construed as improvement in employment within a growing economy and elimination of poverty and inequality--a redistribution of growth. Development should increase and widen the distribution of basic life sustaining goods, increase levels of living, and expand economic and social choices and free people from dependence on other people and servitude to ignorance and poverty. Six basic issues linking population growth and development were identified; the interrelationships between economic, social, and demographic variables were explained. The aims of educational development and educational progress as affected by urbanization were discussed. It is inappropriate to isolate economic, social, and demographic concerns as separate entities and as separate from the development process. The population problem of rapid population growth is intertwined with the problem of unmet human needs; problematic are illiteracy, extreme deprivation, insufficient income to purchase essential health services and basic nutrition, and inadequate diets. Improvements have not kept pace with needs. The theories of Malthus are no longer germane, and demographic transition theory is not as effective in achieving or explaining the reduction of birth rates. An approach which attacks poverty and low quality of life would be directed to core motivations. The hidden momentum of population growth and the impact of literacy and age and sex composition are discussed as features of improvement in quality of life and of fertility reduction. Economic and social development are dependent on human resources, not on capital or material resources. The institutional mechanism for developing human potential is the educational system

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

PubMed

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.

The intrinsic growth rate as a predictor of population viability under climate warming.

PubMed

Amarasekare, Priyanga; Coutinho, Renato M

2013-11-01

1. Lately, there has been interest in using the intrinsic growth rate (rm) to predict the effects of climate warming on ectotherm population viability. However, because rm is calculated using the Euler-Lotka equation, its reliability in predicting population persistence depends on whether ectotherm populations can achieve a stable age/stage distribution in thermally variable environments. Here, we investigate this issue using a mathematical framework that incorporates mechanistic descriptions of temperature effects on vital rates into a stage-structured population model that realistically captures the temperature-induced variability in developmental delays that characterize ectotherm life cycles. 2. We find that populations experiencing seasonal temperature variation converge to a stage distribution whose intra-annual pattern remains invariant across years. As a result, the mean annual per capita growth rate also remains constant between years. The key insight is the mechanism that allows populations converge to a stationary stage distribution. Temperature effects on the biochemical processes (e.g. enzyme kinetics, hormonal regulation) that underlie life-history traits (reproduction, development and mortality) exhibit well-defined thermodynamical properties (e.g. changes in entropy and enthalpy) that lead to predictable outcomes (e.g. reduction in reaction rates or hormonal action at temperature extremes). As a result, life-history traits exhibit a systematic and predictable response to seasonal temperature variation. This in turn leads to temporally predictable temperature responses of the stage distribution and the per capita growth rate. 3. When climate warming causes an increase in the mean annual temperature and/or the amplitude of seasonal fluctuations, the population model predicts the mean annual per capita growth rate to decline to zero within 100 years when warming is slow relative to the developmental period of the organism (0.03-0.05°C per year) and to

Development of disease-specific growth charts in Turner syndrome and Noonan syndrome.

PubMed

Isojima, Tsuyoshi; Yokoya, Susumu

2017-12-01

Many congenital diseases are associated with growth failure, and patients with these diseases have specific growth patterns. As the growth patterns of affected individuals differ from those of normal populations, it is challenging to detect additional conditions that can influence growth using standard growth charts. Disease-specific growth charts are thus very useful tools and can be helpful for understanding the growth pattern and pathogenesis of congenital diseases. In addition, disease-specific growth charts allow doctors to detect deviations from the usual growth patterns for early diagnosis of an additional condition and can be used to evaluate the effects of growth-promoting treatment for patients. When developing these charts, factors that can affect the reliability of the charts should be considered. These factors include the definition of the disease with growth failure, selection bias in the measurements used to develop the charts, secular trends of the subjects, the numbers of subjects of varying ages and ethnicities, and the statistical method used to develop the charts. In this review, we summarize the development of disease-specific growth charts for Japanese individuals with Turner syndrome and Noonan syndrome and evaluate the efforts to collect unbiased measurements of subjects with these diseases. These charts were the only available disease-specific growth charts of Turner syndrome and Noonan syndrome for Asian populations and were developed using a Japanese population. Therefore, when these charts are adopted for Asian populations other than Japanese, different growth patterns should be considered.

Preoperative ketoprofen administration to piglets undergoing castration does not affect subsequent growth performance

PubMed Central

Cassar, Glen; Amezcua, Rocio; Tenbergen, Ryan; Friendship, Robert M.

2014-01-01

The purpose of this study was to determine if treatment of pigs with ketoprofen (3 mg/kg body weight) before castration at 7 days of age would affect subsequent growth during the suckling period. Piglets from 301 litters were treated with ketoprofen or a placebo and weighed at castration and at weaning. There was no difference in growth rate between the 2 groups of pigs. PMID:24381346

Population policy.

PubMed

1987-03-01

Participants in the Seminar on Population Policies for Top-level Policy Makers and Program Managers, meeting in Thailand during January 1987, examined the challenges now facing them regarding the implementation of fertility regulation programs in their respective countries -- Bangladesh, China, India, Indonesia, Malaysia, Nepal, Pakistan, the Philippines, the Republic of Korea, and Thailand. This Seminar was organized to coincide with the completion of an Economic and Social Commission for Asia and the Pacific (ESCAP) study investigating the impact and efficiency of family planning programs in the region. Country studies were reviewed at the Seminar along with policy issues about the status of women, incentive and disincentive programs, and socioeconomic factors affecting fertility. In Bangladesh the government recognizes population growth as its top priority problem related to the socioeconomic development of the country and is working to promote a reorientation strategy from the previous clinic-oriented to a multidimensional family welfare program. China's family planning program seeks to postpone marraige, space the births of children between 3-5 years, and promote the 1-child family. Its goal is to reduce the rate of natural increase from 12/1000 in 1978 to 5/1000 by 1985 and 0 by 2000. India's 7th Five-Year-Plan (1986-90) calls for establishing a 2-child family norm by 2000. In Indonesia the government's population policy includes reducing the rate of population growth, achieving a redistribution of the population, adjusting economic factors, and creating prosperous families. The government of Indonesia reversed its policy to reduce the population growth rate in 1984 and announced its goal of achieving a population of 70 million by 2100 in order to support mass consumption industries. It has created an income tax deduction system favoring large families and maternity benefits for women who have up to 5 children as incentives. Nepal's official policy is to

Effects of recruitment, growth, and exploitation on walleye population size structure in northern Wisconsin lakes

USGS Publications Warehouse

Hansen, Michael J.; Nate, Nancy A.

2014-01-01

We evaluated the dynamics of walleye Sander vitreus population size structure, as indexed by the proportional size distribution (PSD) of quality-length fish, in Escanaba Lake during 1967–2003 and in 204 other lakes in northern Wisconsin during 1990–2011. We estimated PSD from angler-caught walleyes in Escanaba Lake and from spring electrofishing in 204 other lakes, and then related PSD to annual estimates of recruitment to age-3, length at age 3, and annual angling exploitation rate. In Escanaba Lake during 1967–2003, annual estimates of PSD were highly dynamic, growth (positively) explained 35% of PSD variation, recruitment explained only 3% of PSD variation, and exploitation explained only 7% of PSD variation. In 204 other northern Wisconsin lakes during 1990–2011, PSD varied widely among lakes, recruitment (negatively) explained 29% of PSD variation, growth (positively) explained 21% of PSD variation, and exploitation explained only 4% of PSD variation. We conclude that population size structure was most strongly driven by recruitment and growth, rather than exploitation, in northern Wisconsin walleye populations. Studies of other species over wide spatial and temporal ranges of recruitment, growth, and mortality are needed to determine which dynamic rate most strongly influences population size structure of other species. Our findings indicate a need to be cautious about assuming exploitation is a strong driver of walleye population size structure.

Urban population growth and urbanization in the Caribbean.

PubMed

Hope, K R

1985-01-01

The structure, sources, consequences, and policy implications of urbanization and of the rapid growth of the urban population in the Caribbean are examined. In particular, a comparative analysis of the situation in Barbados, Guyana, Jamaica, and Trinidad and Tobago is presented. Data are from a variety of secondary sources, including those published by the United Nations and the World Bank. The need to reorient policies to favor rural rather than urban areas in order to reduce rural-urban migration is noted.

Determining Individual Variation in Growth and Its Implication for Life-History and Population Processes Using the Empirical Bayes Method

PubMed Central

Vincenzi, Simone; Mangel, Marc; Crivelli, Alain J.; Munch, Stephan; Skaug, Hans J.

2014-01-01

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 (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. PMID:25211603

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

PubMed

Vincenzi, Simone; Mangel, Marc; Crivelli, Alain J; Munch, Stephan; Skaug, Hans J

2014-09-01

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.

The balance of planting and mortality in a street tree population

Treesearch

Lara A. Roman; John J. Battles; Joe R. McBride

2013-01-01

Street trees have aesthetic, environmental, human health, and economic benefits in urban ecosystems. Street tree populations are constructed by cycles of planting, growth, death, removal and replacement. The goals of this study were to understand how tree mortality and planting rates affect net population growth, evaluate the shape of the mortality curve, and assess...

MECHANISMS OF FLUID SHEAR-INDUCED INHIBITION OF POPULATION GROWTH IN A RED-TIDE DINOFLAGELLATE

EPA Science Inventory

Net population growth of some dinoflagellates is inhibited by fluid shear at shear stresses comparable with those generated during oceanic turbulence. Decreased net growth may occur through lowered cell division, increased mortality, or both. The dominant mechanism under various ...

Water abstraction affects abundance, size-structure and growth of two threatened cyprinid fishes

PubMed Central

Merciai, Roberto; Molons-Sierra, Carlota; Sabater, Sergi; García-Berthou, Emili

2017-01-01

Hydrologic alteration is a major threat to freshwater biota, and particularly fish, in many river courses around the world. We analyzed and compared the effects of water abstraction on two threatened cyprinid fishes of contrasting ecology (the Mediterranean barbel Barbus meridionalis and the Catalan chub Squalius laietanus) in a Mediterranean stream. We compared abundance, size-structure, growth, and condition of both species across perennial and artificially intermittent reaches affected by water abstraction. Both species were less abundant, had scarce large individuals, and displayed slower growth rates (length-at-age) in intermittent reaches, showing clear detrimental effects of water diversion. Mixed-effect models of scale increments showed variation among individuals and among sites, years and age classes for both species. The larger-sized, water-column species (chub) disappeared or was rare in many intermittent reaches. The barbel present in intermittent reaches showed better somatic condition than in sites with permanent flow, perhaps due to reduced competition after rewetting or colonization by better fitted individuals. This benthic, rheophilic species seems more resilient to moderate water abstraction than chub. Many effects of water flow intermittency were only detected on fish life-history traits when accounting for natural, often non-linear, variation, along upstream-downstream gradients. Our results suggest that abundance was the strongest indicator of effects of water abstraction on fish populations, whereas condition was a more labile trait, rapidly recovering from anthropogenic disturbance. PMID:28414787

Does Size Matter? A Study of Risk Perceptions of Global Population Growth.

PubMed

Dawson, Ian G J; Johnson, Johnnie E V

2017-01-01

The global human population now exceeds 7 billion and is projected to reach 10 billion around 2060. While population growth has been associated with certain benefits (e.g., economies of scale, technological advancements), theoretical models, probabilistic projections, and empirical evidence also indicate that this growth could increase the likelihood of many adverse events (e.g., climate change, resource shortages) and the impact of these events, as more people are exposed to the outcomes. While concerns about these issues are well-documented in the academic literature, there is little evidence concerning the public's perceptions of the risks associated with global population growth (GPG) and how these perceptions are likely to influence related decisions. To address these issues, we conducted a U.K.-based study that examined respondents' risk perceptions of GPG, their willingness to embrace mitigation/precautionary behaviors, and reasons for variations in these two factors. We found that GPG is perceived as a moderate-to-high risk, with concerns about the increased likelihood of resource shortages, ecological damage, and violent conflict being foremost. Respondents believed that the worst effects of GPG would arrive around 2050 and would be experienced by the world's poorest people. Respondents who perceived greater levels of risk from GPG were generally those who indicated a greater willingness to embrace mitigation behaviors (e.g., reduce resource consumption) and preventative actions (e.g., support political action to limit growth). We discuss how our findings might be utilized to better manage the potential challenges associated with GPG and we suggest several directions for further research. © 2016 Society for Risk Analysis.

Teaching Population Growth Using Cultures of Vinegar Eels, "Turbatrix aceti" (Nematoda)

ERIC Educational Resources Information Center

Wallace, Robert L.

2005-01-01

A simple laboratory exercise is presented that follows the population growth of the common vinegar eel, "Turbatrix aceti" (Nematoda), in a microcosm using a simple culture medium. It lends itself to an exercise in a single semester course. (Contains 4 figures.)

Cross-scale interactions affect tree growth and intrinsic water ...

EPA Pesticide Factsheets

1. We investigated the potential of cross-scale interactions to affect the outcome of density reduction in a large-scale silvicultural experiment. 2. We measured tree growth and intrinsic water-use efficiency (iWUE) based on stable carbon isotopes (13C) to investigate the impacts of thinning across a range of progressively finer spatial scales: site, stand, hillslope position, and neighborhood position. In particular, we focused on the influence of thinning beyond the boundaries of thinned stands to include impacts on downslope and neighboring stands across sites varying in soil moisture. 3. Trees at the wet site responded to thinning with increased growth when compared with trees at the dry site. Additionally, trees in thinned stands at the dry site responded with increased iWUE while trees in thinned stands at the wet site showed no difference in iWUE compared to unthinned stands. 4. We hypothesized that water is not the primary limiting factor for growth at our sites, but that thinning released other resources, such as growing space or nutrients to drive the growth response. At progressively finer spatial scales we found that the responses of trees was not driven by hillslope location (i.e., downslope of thinning) but to changes in local neighborhood tree density. 5. The results of this study demonstrated that water can be viewed as an “agent” that allows us to investigate cross-scale interactions as it links coarse to finer spatial scales and vice ver

ZnO Nanoparticles Affect Bacillus subtilis Cell Growth and Biofilm Formation.

PubMed

Hsueh, Yi-Huang; Ke, Wan-Ju; Hsieh, Chien-Te; Lin, Kuen-Song; Tzou, Dong-Ying; Chiang, Chao-Lung

2015-01-01

Zinc oxide nanoparticles (ZnO NPs) are an important antimicrobial additive in many industrial applications. However, mass-produced ZnO NPs are ultimately disposed of in the environment, which can threaten soil-dwelling microorganisms that play important roles in biodegradation, nutrient recycling, plant protection, and ecological balance. This study sought to understand how ZnO NPs affect Bacillus subtilis, a plant-beneficial bacterium ubiquitously found in soil. The impact of ZnO NPs on B. subtilis growth, FtsZ ring formation, cytosolic protein activity, and biofilm formation were assessed, and our results show that B. subtilis growth is inhibited by high concentrations of ZnO NPs (≥ 50 ppm), with cells exhibiting a prolonged lag phase and delayed medial FtsZ ring formation. RedoxSensor and Phag-GFP fluorescence data further show that at ZnO-NP concentrations above 50 ppm, B. subtilis reductase activity, membrane stability, and protein expression all decrease. SDS-PAGE Stains-All staining results and FT-IR data further demonstrate that ZnO NPs negatively affect exopolysaccharide production. Moreover, it was found that B. subtilis biofilm surface structures became smooth under ZnO-NP concentrations of only 5-10 ppm, with concentrations ≤ 25 ppm significantly reducing biofilm formation activity. XANES and EXAFS spectra analysis further confirmed the presence of ZnO in co-cultured B. subtilis cells, which suggests penetration of cell membranes by either ZnO NPs or toxic Zn+ ions from ionized ZnO NPs, the latter of which may be deionized to ZnO within bacterial cells. Together, these results demonstrate that ZnO NPs can affect B. subtilis viability through the inhibition of cell growth, cytosolic protein expression, and biofilm formation, and suggest that future ZnO-NP waste management strategies would do well to mitigate the potential environmental impact engendered by the disposal of these nanoparticles.

ZnO Nanoparticles Affect Bacillus subtilis Cell Growth and Biofilm Formation

PubMed Central

Hsueh, Yi-Huang; Ke, Wan-Ju; Hsieh, Chien-Te; Lin, Kuen-Song; Tzou, Dong-Ying; Chiang, Chao-Lung

2015-01-01

Zinc oxide nanoparticles (ZnO NPs) are an important antimicrobial additive in many industrial applications. However, mass-produced ZnO NPs are ultimately disposed of in the environment, which can threaten soil-dwelling microorganisms that play important roles in biodegradation, nutrient recycling, plant protection, and ecological balance. This study sought to understand how ZnO NPs affect Bacillus subtilis, a plant-beneficial bacterium ubiquitously found in soil. The impact of ZnO NPs on B. subtilis growth, FtsZ ring formation, cytosolic protein activity, and biofilm formation were assessed, and our results show that B. subtilis growth is inhibited by high concentrations of ZnO NPs (≥ 50 ppm), with cells exhibiting a prolonged lag phase and delayed medial FtsZ ring formation. RedoxSensor and Phag-GFP fluorescence data further show that at ZnO-NP concentrations above 50 ppm, B. subtilis reductase activity, membrane stability, and protein expression all decrease. SDS-PAGE Stains-All staining results and FT-IR data further demonstrate that ZnO NPs negatively affect exopolysaccharide production. Moreover, it was found that B. subtilis biofilm surface structures became smooth under ZnO-NP concentrations of only 5–10 ppm, with concentrations ≤ 25 ppm significantly reducing biofilm formation activity. XANES and EXAFS spectra analysis further confirmed the presence of ZnO in co-cultured B. subtilis cells, which suggests penetration of cell membranes by either ZnO NPs or toxic Zn+ ions from ionized ZnO NPs, the latter of which may be deionized to ZnO within bacterial cells. Together, these results demonstrate that ZnO NPs can affect B. subtilis viability through the inhibition of cell growth, cytosolic protein expression, and biofilm formation, and suggest that future ZnO-NP waste management strategies would do well to mitigate the potential environmental impact engendered by the disposal of these nanoparticles. PMID:26039692

Nutritional status and growth in pediatric Crohn's disease: a population-based study.

PubMed

Vasseur, Francis; Gower-Rousseau, Corinne; Vernier-Massouille, Gwenola; Dupas, Jean Louis; Merle, Veronique; Merlin, Beatrice; Lerebours, Eric; Savoye, Guillaume; Salomez, Jean Louis; Cortot, Antoine; Colombel, Jean Frederic; Turck, Dominique

2010-08-01

Growth retardation and malnutrition are major features of pediatric Crohn's disease (CD). We examined nutritional and growth parameters from diagnosis to maximal follow-up in a population-based pediatric cohort, and we determined predictive factors. A total of 261 patients (156 boys, 105 girls) with onset of CD before the age of 17 were identified from 1988 to 2004 through the EPIMAD registry (Registre des Maladies Inflammatoires Chroniques de l'Intestin) in northern France. Median age at diagnosis was 13 years (11.2-15.4) and median follow-up was 73 months (46-114). Z-scores of height/age, weight/age, and body mass index (BMI)/age were determined. Multivariate stepwise regression analysis identified predictive factors for malnutrition and growth retardation at maximal follow-up. At diagnosis, 25 children (9.5%) showed height less than -2 s.d., 70 (27%) weight less than -2 s.d., and 84 (32%) BMI less than -2 s.d. At maximal follow-up, growth retardation was present in 18 children (6.9%), whereas 40 (15%) had malnutrition. Nutritional status was more severely impaired in children with stricturing disease. Growth and nutritional retardation at diagnosis, young age, male gender, and extraintestinal manifestations at diagnosis were indicators of poor prognosis. A significant compensation was observed for weight and BMI in both genders and for height in girls. No treatment was associated with height, weight, or BMI at maximal follow-up. In our pediatric population-based study, growth retardation and severe malnutrition were still present at maximal follow-up in 6.9 and 15% of CD children, respectively. Young boys with substantial inflammatory manifestations of CD have a higher risk of subsequent growth failure, especially when growth retardation is present at diagnosis.

Single and combined effects of microplastics and copper on the population growth of the marine microalgae Tetraselmis chuii

NASA Astrophysics Data System (ADS)

Davarpanah, Elham; Guilhermino, Lúcia

2015-12-01

As the accumulation of microplastics continues to rise in the marine environment, more knowledge on their potential toxic effects on marine organisms is needed to assess their risks to environmental and human health. Thus, the goal of the present study was to investigate the effects of fluorescent red polyethylene plastic micro-spheres 1-5 μm diameter (used as microplastic model and hereafter indicated as MP), alone and in mixture with copper, on the population growth of the marine microalgae Tetraselmis chuii. Two null hypotheses were tested: (H01) Exposure to MP concentrations in ppb range does not affect the average specific growth rate of T. chuii; (H02) MP do not interact with the toxicity of copper to T. chuii. In laboratory bioassays, T. chuii cultures were exposed for 96 h to MP concentrations ranging from 0.046 to 1.472 mg/l), concentrations of copper alone ranging from 0.02 to 0.64 mg/l, and the same concentrations of copper in the presence of 0.184 mg/l of MP in test media. No significant effects of MP on T. chuii population growth were found (p > 0.05), leading to the acceptance of H01. Copper alone significantly decreased the population growth of T. chuii with EC10, EC20 and EC50 of 0.009, 0.023 and 0.139 mg/l, respectively. The corresponding values in the presence of MP were 0.012, 0.029 and 0.145 mg/l, respectively. Moreover, the study found no significant differences between the toxicity curves of copper in the presence and absence of MP (p > 0.05), leading to the acceptance of H02. Despite these findings, because microplastics are known to adsorb and accumulate copper, aged pellets more than virgin ones, and the toxicity of smaller particles may be higher, further studies on the combined effects of copper and microplastics on microalgae should be performed, especially under long-term exposures to nano-sized aged microplastics.

Matrix models for size-structured populations: unrealistic fast growth or simply diffusion?

PubMed

Picard, Nicolas; Liang, Jingjing

2014-01-01

Matrix population models are widely used to study population dynamics but have been criticized because their outputs are sensitive to the dimension of the matrix (or, equivalently, to the class width). This sensitivity is concerning for the population growth rate (λ) because this is an intrinsic characteristic of the population that should not depend on the model specification. It has been suggested that the sensitivity of λ to matrix dimension was linked to the existence of fast pathways (i.e. the fraction of individuals that systematically move up a class), whose proportion increases when class width increases. We showed that for matrix population models with growth transition only from class i to class i + 1, λ was independent of the class width when the mortality and the recruitment rates were constant, irrespective of the growth rate. We also showed that if there were indeed fast pathways, there were also in about the same proportion slow pathways (i.e. the fraction of individuals that systematically remained in the same class), and that they jointly act as a diffusion process (where diffusion here is the movement in size of an individual whose size increments are random according to a normal distribution with mean zero). For 53 tree species from a tropical rain forest in the Central African Republic, the diffusion resulting from common matrix dimensions was much stronger than would be realistic. Yet, the sensitivity of λ to matrix dimension for a class width in the range 1-10 cm was small, much smaller than the sampling uncertainty on the value of λ. Moreover, λ could either increase or decrease when class width increased depending on the species. Overall, even if the class width should be kept small enough to limit diffusion, it had little impact on the estimate of λ for tree species.

Drivers of seabird population recovery on New Zealand islands after predator eradication.

PubMed

Buxton, Rachel T; Jones, Christopher; Moller, Henrik; Towns, David R

2014-04-01

Eradication of introduced mammalian predators from islands has become increasingly common, with over 800 successful projects around the world. Historically, introduced predators extirpated or reduced the size of many seabird populations, changing the dynamics of entire island ecosystems. Although the primary outcome of many eradication projects is the restoration of affected seabird populations, natural population responses are rarely documented and mechanisms are poorly understood. We used a generic model of seabird colony growth to identify key predictor variables relevant to recovery or recolonization. We used generalized linear mixed models to test the importance of these variables in driving seabird population responses after predator eradication on islands around New Zealand. The most influential variable affecting recolonization of seabirds around New Zealand was the distance to a source population, with few cases of recolonization without a source population ≤25 km away. Colony growth was most affected by metapopulation status; there was little colony growth in species with a declining status. These characteristics may facilitate the prioritization of newly predator-free islands for active management. Although we found some evidence documenting natural recovery, generally this topic was understudied. Our results suggest that in order to guide management strategies, more effort should be allocated to monitoring wildlife response after eradication. © 2014 Society for Conservation Biology.

Analysing the natural population growth of a large marine mammal after a depletive harvest.

PubMed

Romero, M A; Grandi, M F; Koen-Alonso, M; Svendsen, G; Ocampo Reinaldo, M; García, N A; Dans, S L; González, R; Crespo, E A

2017-07-13

An understanding of the underlying processes and comprehensive history of population growth after a harvest-driven depletion is necessary when assessing the long-term effectiveness of management and conservation strategies. The South American sea lion (SASL), Otaria flavescens, is the most conspicuous marine mammal along the South American coasts, where it has been heavily exploited. As a consequence of this exploitation, many of its populations were decimated during the early 20th century but currently show a clear recovery. The aim of this study was to assess SASL population recovery by applying a Bayesian state-space modelling framework. We were particularly interested in understanding how the population responds at low densities, how human-induced mortality interplays with natural mechanisms, and how density-dependence may regulate population growth. The observed population trajectory of SASL shows a non-linear relationship with density, recovering with a maximum increase rate of 0.055. However, 50 years after hunting cessation, the population still represents only 40% of its pre-exploitation abundance. Considering that the SASL population in this region represents approximately 72% of the species abundance within the Atlantic Ocean, the present analysis provides insights into the potential mechanisms regulating the dynamics of SASL populations across the global distributional range of the species.

Individual and Population-Level Impacts of an Emerging Poxvirus Disease in a Wild Population of Great Tits

PubMed Central

Lachish, Shelly; Bonsall, Michael B.; Lawson, Becki; Cunningham, Andrew A.; Sheldon, Ben C.

2012-01-01

Emerging infectious diseases of wildlife can have severe effects on host populations and constitute a pressing problem for biodiversity conservation. Paridae pox is an unusually severe form of avipoxvirus infection that has recently been identified as an emerging infectious disease particularly affecting an abundant songbird, the great tit (Parus major), in Great Britain. In this study, we study the invasion and establishment of Paridae pox in a long-term monitored population of wild great tits to (i) quantify the impact of this novel pathogen on host fitness and (ii) determine the potential threat it poses to population persistence. We show that Paridae pox significantly reduces the reproductive output of great tits by reducing the ability of parents to fledge young successfully and rear those young to independence. Our results also suggested that pathogen transmission from diseased parents to their offspring was possible, and that disease entails severe mortality costs for affected chicks. Application of multistate mark-recapture modelling showed that Paridae pox causes significant reductions to host survival, with particularly large effects observed for juvenile survival. Using an age-structured population model, we demonstrate that Paridae pox has the potential to reduce population growth rate, primarily through negative impacts on host survival rates. However, at currently observed prevalence, significant disease-induced population decline seems unlikely, although pox prevalence may be underestimated if capture probability of diseased individuals is low. Despite this, because pox-affected model populations exhibited lower average growth rates, this emerging infectious disease has the potential to reduce the resilience of populations to other environmental factors that reduce population size. PMID:23185263

Fifty years of population growth and absorption of labor in Brazil: from 1950 to 2000.

PubMed

Paiva, P D

1997-01-01

For a long time, the Brazilian population has grown at a relatively high rate, and only recently has the process of demographic transition intensified in the country. While the associated decline in fertility could result in a future decline in the size of the working-age population, it could also lead to an increase in female participation in the labor market. Brazil's economy is performing well, with gross domestic product (GDP) growing at an average annual rate of 7.1% during 1947-80. Marked growth in industrial employment opportunities has accompanied this growth in GDP. The size of the informal sector, however, has not decreased in similar proportion, while the 1981-83 economic crisis caused urban employment levels to drop, especially in industry and construction. Moreover, the level of rural-urban migration has increased and the agricultural employment index has fallen. The author evaluates past growth trends of the Economically Active Population (EAP) and of employment in Brazil, and assesses the potential growth of the labor force until the year 2000.

Inductions of reproduction and population growth in the generalist predator Cyrtorhinus lividipennis (Hemiptera: Miridae) exposed to sub-lethal concentrations of insecticides.

PubMed

Lu, Weiwei; Xu, Qiujing; Zhu, Jun; Liu, Chen; Ge, Linquan; Yang, Guoqing; Liu, Fang

2017-08-01

The miridbug, Cyrtorhinus lividipennis, is a significant predacious enemy of rice planthoppers. The effects of sub-lethal concentrations of triazophos, deltamethrin and imidacloprid on fecundity, egg hatchability, expression levels of genes associated with reproduction, and population growth in C. lividipennis were investigated. The fecundities for three pair combinations (♀ c × ♂ t , ♀ t × ♂ c and ♀ t × ♂ t ) treated with sub-lethal concentrations of the insecticides triazophos, deltamethrin and imidacloprid (LC 10 and LC 20 ) showed a significant increase compared to the untreated pairs (♀ c × ♂ c ). However, sub-lethal concentration treatments did not affect the egg hatchability. The ClVg expression levels of female adults exposed to triazophos, deltamethrin and imidacloprid (LC 20 ) increased by 52.6, 48.9 and 91.2%, respectively. The ClSPATA13 expression level of adult males exposed to triazophos, deltamethrim and imidacloprid (LC 20 ) increased by 80.7, 41.3 and 48.3%, respectively. Furthermore, sub-lethal concentrations of insecticides (LC 20 ) caused increased population numbers in C. lividipennis. Sub-lethal concentrations of triazophos, deltamethrin and imidacloprid stimulated reproduction and enhanced population growth of C. lividipennis. The reproductive stimulation might result from the up-regulation of ClVg or ClSPATA13. These findings may be useful in mediating populations of planthoppers. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Strength of Rocks Affected by Deformation Enhanced Grain Growth

NASA Astrophysics Data System (ADS)

Kellermann Slotemaker, A.; de Bresser, H.; Spiers, C.

2005-12-01

One way of looking into the possibility of long-term strength changes in the lithosphere is to study transient effects resulting from modifications of the microstructure of rocks. It is generally accepted that mechanical weakening may occur due to progressive grain size refinement resulting from dynamic recrystallization. A decrease in grain size may induce a switch from creep controlled by grain size insensitive dislocation mechanisms to creep governed by grain size sensitive (GSS) mechanisms involving diffusion and grain boundary sliding processes. This switch forms a well-known scenario to explain localization in the lithosphere. However, fine-grained rocks in localized deformation zones are prone to grain coarsening due to surface energy driven grain boundary migration (SED-GBM). This might harden the rock, affecting its role in localizing strain in the long term. The question has arisen if grain growth by SED-GBM in a rock deforming in the GSS creep field can be significantly affected by strain. The broad aim of this study is to shed more light onto this. We have experimentally investigated the microstructural and strength evolution of fine-grained (~0.6 μm) synthetic forsterite and Fe-bearing olivine aggregates that coarsen in grain size while deforming by GSS creep at elevated pressure (600 MPa) and temperature (850-1000 °C). The materials were prepared by `sol-gel' method and contained 0.3-0.5 wt% water and 5-10 vol% enstatite. We performed i) static heat treatment tests of various time durations involving hot isostatic pressing (HIP), and ii) heat treatment tests starting with HIP and continuing with deformation up to 45% axial strain at strain rates in the range 4x10-7 - 1x10-4 s-1. Microstructures were characterized by analyzing full grain size distributions and textures using SEM/EBSD. In addition to the experiments, we studied microstructural evolution in simple two-dimensional numerical models, combining deformation and SED-GBM by means of the

Investment, population growth and GNP as determinants of US immigration.

PubMed

Kritz, M M

1998-09-01

Northern countries typically attract migrants from poorer countries because of the formers' high wage rates and demand for labor. In particular, the US receives large numbers of legal migrants from almost every country and region of the world. This paper explores the determinants of permanent emigration to the US during 1989-93 using data drawn from the US Immigration and Naturalization Service (INS) Annual Tapes for the period. The analysis is restricted to only legal migration from 150 countries, and specifically investigates whether emigration to the US during 1989-93 can be accounted for by demographic and economic conditions in sending countries, or by levels of US investment in sending countries. No support is found for claims that rapid population growth and US investment fuel US immigration; emigration is comparatively far lower from countries experiencing rapid population growth and not significantly correlated with US investment, while the US typically invests the most in the more developed countries which send relatively few migrants to the US. Geographic proximity is the most important correlate of migration, followed by the population size of sending countries, which is negatively related to emigration. Some evidence was found that emigration will decrease as countries develop. Who a country decides to admit and how many people are admitted depend mainly upon public policy and very little upon the economic and demographic conditions of sending countries.

Some Population Trends Affecting Extension Education and Other Community Programs.

ERIC Educational Resources Information Center

Niederfrank, E. J.

Population trends affecting extension education and other community programs reveal that there will be large increases in numbers of young adult and young middleaged households, beginning in the next five years. The number of households in the United States will rise to 84.4 million by July 1985, representing an increase of 26.3 million over the…

Risk factors for mortality in landslide- and flood-affected populations in Uganda.

PubMed

Agrawal, Shreya; Gorokhovich, Yuri; Doocy, Shannon

2013-01-01

Assess mortality risk factors including age, sex, and disaster type, in the March 2010 floods and landslides in Eastern Uganda and to compare time period, cause, location, and receipt of medical care among landslide and flood fatalities. A stratified cluster survey was conducted of 802 affected households in community and camp locations. Flood and landslide affected populations in the East Uganda the districts of Baduda and Butaleja. Adult household members in 802 households were surveyed regarding household member deaths in the floods and landslides areas. The primary outcome measure was the odds of death associated with age, sex, and disaster type (flood or landslide). The secondary outcome measure was the odds of event (landslide or flood) among fatalities associated with sex, age, time period of death, and cause of death. The odds of death were significantly higher in landslide affected populations than in flood affected populations (OR 3.06, 95% CI 2.20-4.25, p < 0.001). Time period of death (p = 0.016), type of death (p < 0.001), death after seeking medical care (p = 0.033), month of death (p < 0.001), and cause of death (p < 0.001) were significantly associated with increased odds of death due to landslides as compared to floods. More deaths occurred due to landslides than floods, and landslide deaths were more immediate, with a majority occurring on the day of the event. Females and younger age groups faced a greater risk of death from the landslide than the flood.

Recent and prospective population trends in Malaysia.

PubMed

Jones, G W; Tan, P C

1985-09-01

Recent population trends in Malaysia are reviewed, with the focus on Peninsular Malaysia. Separate consideration is given to population growth between 1970 and 1980; mortality trends; period and cohort fertility trends; factors affecting fertility, including changes in age structure, nuptiality, and other socioeconomic and demographic changes; and the recent development of a pro-natalist policy involving a goal of a population of 70 million by 2050.

Bacterial populations growth under co- and counter-flow condition

NASA Astrophysics Data System (ADS)

Tesser, Francesca; Zeegers, Jos C. H.; Clercx, Herman J. H.; Toschi, Federico

2014-11-01

For organisms living in a liquid ecosystem, flow and flow gradients play a major role on the population level: the flow has a dual role as it transports the nutrient while dispersing the individuals. In absence of flow and under homogeneous conditions, the growth of a population towards an empty region is usually described by a reaction diffusion equation. The solution predicts the expansion as a wave front (Fisher wave) proceeding at constant speed, till the carrying capacity is reached everywhere. The effect of fluid flow, however, is not well understood and the interplay between transport of individuals and nutrient opens a wide scenario of possible behaviors. In this work, we experimentally observe non-motile E. coli bacteria spreading inside rectangular channels in a PDMS microfluidic device. By use of a fluorescent microscope we analyze the dynamics of the population density subjected to different co- and counter-flow conditions and shear rates.

Is There Hidden Potential for Rural Population Growth in Sweden?

ERIC Educational Resources Information Center

Niedomysl, Thomas; Amcoff, Jan

2011-01-01

Rural depopulation is a concern in many countries, and various policy initiatives have been taken to combat such trends. This article examines whether hidden potential for rural population growth can be found in Sweden. If such potential exists, it implies that the development prospects for many rural areas are not as unpromising as they may seem…

The Economic Base of Recent Population Growth in Nonmetropolitan Settings.

ERIC Educational Resources Information Center

Long, Larry; DeAre, Diana

In the late 1970s both jobs and population were growing more rapidly outside metropolitan areas. As a group, nonmetropolitan counties not adjacent to a metropolitan area experienced a faster rate of employment growth than metropolitan areas between 1975-79. Even in rural counties (no urban place of 2,500 or more) not adjacent to a metropolitan…

A note on the status of women as a factor in population growth in less developed countries.

PubMed

Laidlaw, K A; Pugh, M D; Stockwell, E G

1980-01-01

The 1978 U.S. Bureau of the Census reported 4.3 billion as the world's population. 3.1 billion were living in the less developed areas where life is characterized by poverty and low levels of material well-being. In the develop countries the per capita income averaged $490, compared to $5,210 in developed areas. Little attention has been paid to the status of women in developing countries, where the impact of development often has a negative effect. As a measure of women's status, rates are given for male/female infant mortality. If the ratio is less than 1.14 the status of women is low. If the is 1.15-1.24 the status is medium. If the ratio is 1.25 and over, women enjoy high status. In countries where women have low status the population growth ra averages 3%. Where the status of women is medium, the growth rate is 2.5%. I countries of high status the population growth rate is 2.2. Further research is needed on correlations between population and economic growth, with particula emphasis on subtle factors behind population/economic development.

Population policy in the United States.

PubMed

Corsa, L

1979-01-01

The importance of population in the richer nations is seen in terms of increasing demand for fuels and the resultant pollution of air and water. All governments have a population policy, even if it negative and even if it is impied. U.S. federal funding for family planning, lack of funding for abortion, and immigration laws make up part of the U.S. population policy, an inconsistent policy. The 1970-72 Commission of Population Growth and the American Future called for stabilized growth, i.e. zero population growth. This is also the position of the Sierra Club and other organizations. So far, American presidents have not stated their position on the issue. In order to formulate a national population policy, the values must be recognized which a policy would affect. All national agovernments should provide widespread population education activities, provide easily available and safe family planning services, and incorporate demographic data into their planning. Population policy must be comprehensive and longterm. In the case of the U.S., it msut carry over from 1 administration to the next. The U.S. government has lagged behind in formulation of population policy. Private sector groups, e.g., the Sierra Club, must now take the lead.

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

PubMed

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.

Variations in growth, survival and carbon isotope composition (delta(13)C) among Pinus pinaster populations of different geographic origins.

PubMed

Correia, Isabel; Almeida, Maria Helena; Aguiar, Alexandre; Alía, Ricardo; David, Teresa Soares; Pereira, João Santos

2008-10-01

To evaluate differences in growth and adaptability of maritime pine (Pinus pinaster Ait.), we studied growth, polycyclism, needle tissue carbon isotope composition (delta(13)C) as an estimate of water-use efficiency (WUE) and survival of seven populations at 10 years of age growing in a performance trial at a provenance test site in Escaroupim, Portugal. Six populations were from relatively high rainfall sites in Portugal and southwestern France (Atlantic group), and one population was from a more arid Mediterranean site in Spain. There were significant differences between some populations in total height, diameter at breast height, delta(13)C of bulk needle tissue, polycyclism and survival. A population from central Portugal (Leiria, on the Atlantic coast) was the tallest and had the lowest delta(13)C. Overall, the variation in delta(13)C was better explained by the mean minimum temperatures of the coldest month than by annual precipitation at the place of origin. Analyses of the relationships between delta(13)C and growth or survival revealed a distinct pattern for the Mediterranean population, with low delta(13)C (and WUE) associated with the lowest growth potential and reduced survival. There were significant negative correlations between delta(13)C and height or survival in the Atlantic group. Variation in polycyclism was correlated with annual precipitation at the place of origin. Some Atlantic populations maintained a high growth potential while experiencing moderate water stress. A detailed knowledge of the relationships between growth, survival and delta(13)C in contrasting environments will enhance our ability to select populations for forestry or conservation.

Fetal growth and psychiatric and socioeconomic problems: population-based sibling comparison

PubMed Central

Class, Quetzal A.; Rickert, Martin E.; Larsson, Henrik; Lichtenstein, Paul; D’Onofrio, Brian M.

2014-01-01

Background It is unclear whether associations between fetal growth and psychiatric and socioeconomic problems are consistent with causal mechanisms. Aims To estimate the extent to which associations are a result of unmeasured confounding factors using a sibling-comparison approach. Method We predicted outcomes from continuously measured birth weight in a Swedish population cohort (n = 3 291 773), while controlling for measured and unmeasured confounding. Results In the population, lower birth weight (⩽2500 g) increased the risk of all outcomes. Sibling-comparison models indicated that lower birth weight independently predicted increased risk for autism spectrum disorder (hazard ratio for low birth weight = 2.44, 95% CI 1.99-2.97) and attention-deficit hyperactivity disorder. Although attenuated, associations remained for psychotic or bipolar disorder and educational problems. Associations with suicide attempt, substance use problems and social welfare receipt, however, were fully attenuated in sibling comparisons. Conclusions Results suggest that fetal growth, and factors that influence it, contribute to psychiatric and socioeconomic problems. PMID:25257067

Fetal growth and psychiatric and socioeconomic problems: population-based sibling comparison.

PubMed

Class, Quetzal A; Rickert, Martin E; Larsson, Henrik; Lichtenstein, Paul; D'Onofrio, Brian M

2014-11-01

It is unclear whether associations between fetal growth and psychiatric and socioeconomic problems are consistent with causal mechanisms. To estimate the extent to which associations are a result of unmeasured confounding factors using a sibling-comparison approach. We predicted outcomes from continuously measured birth weight in a Swedish population cohort (n = 3 291 773), while controlling for measured and unmeasured confounding. In the population, lower birth weight (⩽ 2500 g) increased the risk of all outcomes. Sibling-comparison models indicated that lower birth weight independently predicted increased risk for autism spectrum disorder (hazard ratio for low birth weight = 2.44, 95% CI 1.99-2.97) and attention-deficit hyperactivity disorder. Although attenuated, associations remained for psychotic or bipolar disorder and educational problems. Associations with suicide attempt, substance use problems and social welfare receipt, however, were fully attenuated in sibling comparisons. Results suggest that fetal growth, and factors that influence it, contribute to psychiatric and socioeconomic problems. Royal College of Psychiatrists.

Associations of DNA polymorphisms in growth hormone and its transcriptional regulators with growth and carcass traits in two populations of Brangus bulls.

PubMed

Thomas, M G; Enns, R M; Shirley, K L; Garcia, M D; Garrett, A J; Silver, G A

2007-03-30

Sequence polymorphisms in the growth hormone (GH) gene and its transcriptional regulators, Pit-1 and Prop-1, were evaluated for associations with growth and carcass traits in two populations of Brangus bulls Chihuahuan Desert Rangeland Research Center (CDRRC, N = 248 from 14 sires) and a cooperating breeding program (COOP, N = 186 from 34 sires). Polymorphisms were SNP mutations in intron 4 (C/T) and exon V (C/G) in GH, A/G in exon VI in Pit-1, and A/G in exon III in Prop-1. In the COOP population, bulls of Pit-1 GG genotype had a significantly greater percentage of intramuscular fat than bulls of the AA or AG genotype, and bulls of the Prop-1 AA genotype had significantly greater scrotal circumference than bulls of AG or GG genotypes at ~365 days of age. Also, heterozygous genotypes for the two GH polymorphisms appeared advantageous for traits of muscularity and adiposity in the COOP population. The heterozygous genotype of GH intron 4 SNP was associated with advantages in weight gain, scrotal circumference, and fat thickness in the CDRRC population. The two GH polymorphisms accounted for >/=27.7% of the variation in these traits in the CDRRC population; however, R(2) was <5% in the COOP population. Based on haplotype analyses the two GH SNPs appeared to be in phase; the haplotype analyses also paralleled with the genotype analyses. Polymorphisms in GH and its transcriptional regulators appear to be predictors of growth and carcass traits in Brangus bulls, particularly those with heterozygous GH genotypes.

Disruption of the lower food web in Lake Ontario: Did it affect alewife growth or condition?

USGS Publications Warehouse

O'Gorman, R.; Prindle, S.E.; Lantry, J.R.; Lantry, B.F.

2008-01-01

From the early 1980s to the late 1990s, a succession of non-native invertebrates colonized Lake Ontario and the suite of consequences caused by their colonization became known as "food web disruption". For example, the native burrowing amphipod Diporeia spp., a key link in the profundal food web, declined to near absence, exotic predaceous cladocerans with long spines proliferated, altering the zooplankton community, and depth distributions of fishes shifted. These changes had the potential to affect growth and condition of planktivorous alewife Alosa pseudoharengus, the most abundant fish in the lake. To determine if food web disruption affected alewife, we used change-point analysis to examine alewife growth and adult alewife condition during 1976-2006 and analysis-of-variance to determine if values between change points differed significantly. There were no change points in growth during the first year of life. Of three change points in growth during the second year of life, one coincided with the shift in springtime distribution of alewife to deeper water but it was not associated with a significant change in growth. After the second year of life, no change points in growth were evident, although growth in the third year of life spiked in those years when Bythotrephes, the largest of the exotic cladocerans, was abundant suggesting that it was a profitable prey item for age-2 fish. We detected two change points in condition of adult alewife in fall, but the first occurred in 1981, well before disruption began. A second change point occurred in 2003, well after disruption began. After the springtime distribution of alewife shifted deeper during 1992-1994, growth in the first two years of life became more variable, and growth in years of life two and older became correlated (P < 0.05). In conclusion, food web disruption had no negative affect on growth and condition of alewife in Lake Ontario although it appears to have resulted in growth in the first two years of

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

PubMed

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

Effects of red, far-red and blue light in maintaining growth in latitudinal populations of Norway spruce (Picea abies).

PubMed

Mølmann, Jørgen Alexander; Junttila, Olavi; Johnsen, Oystein; Olsen, Jorunn Elisabeth

2006-02-01

Seedlings of trees with a free growth pattern cease growth when night-lengths become shorter than a critical value, and this critical night-length (CNL) decreases with increasing latitude of origin. In northern populations, the light quality also appears to play an important role and a clinal variation in requirement for far-red (FR) light has been documented. In this study we dissected the light quality requirements for maintaining growth in different latitudinal populations of Norway spruce (Picea abies (L.) H. Karst.) using light emitting diodes for red (R), FR and blue (B) light, as 12 h day extension to provide 24 h photoperiod. At equal spectral photon flux, FR light was more effective than R light in maintaining growth, and the requirement of both R and FR increased with northern latitude of origin. One-to-one mixtures of R and FR light were more effective in maintaining growth than either FR or R light alone, indicating a possible interaction between R and FR light maintaining growth. Using the blue light as day extension could not prevent growth cessation in any of the populations, but delayed the bud set slightly in all populations. Our results suggest that phytochrome(s) are the primary photoreceptors in high irradiance responses maintaining growth in Norway spruce seedlings.

Physical Growth of the Shuar: Height, Weight, and BMI References for an Indigenous Amazonian Population

PubMed Central

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.

2015-01-01

Objectives 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. Methods Mixed-longitudinal measures of height, weight, and 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 GAMLSS. Pseudo-velocity and LMS curves were generated to further investigate Shuar patterns of growth and to facilitate comparison with U.S. CDC and multinational WHO growth references. Results 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. Conclusions 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. PMID:26126793

[Population and crisis. Economic inflexibility or demographic subordination].

PubMed

Morelos, J B

1989-01-01

Much speculation, fact-based and subjective, has centered on the links between population and economic crisis, and between population and progress. In the past, famines directly affected the size and dynamics of population in affected regions, and such cycles inspired theories that regarded subsistence as the adjustment mechanism for demographic regimes. Population has alternatively been viewed as a crucial factor of production and a force for modernization and progress. After World War I and the Great Depression, many economists believed that population growth would be indispensable for renewing economic expansion. The favorable view of population growth in Mexico led to measures to repatriate emigrants, attract immigrants, and improve health conditions. The gross national product grew by around 6.0% annually on average between 1940 and 1960, and the per capita GNP by about 3%. Demographic dynamics acquired momentum by the 1960s, with high growth rates, a young age structure, considerable demographic inertia, and relative predominance of the urban population. Indications began to appear that a primarily economic solution to achieving full development would be unlikely. The polarization of development, distributive insufficiency, distortions in exchange relations for agricultural products, and incorporation of inappropriate technologies were factors decreasing the ability of the economy to respond adequately to population demands. National development was insufficient to meet growing demographic pressures in the labor market, educational system, housing, and urban services. The adjustment programs reduced even further the flexibility of the government to respond to pressures. Expectations for the future have been seriously compromised by the fall of real incomes.

Lifetime Prevalence and Correlates of Schizophrenia-Spectrum, Affective, and Other Non-affective Psychotic Disorders in the Chinese Adult Population.

PubMed

Chang, Wing Chung; Wong, Corine Sau Man; Chen, Eric Yu Hai; Lam, Linda Chiu Wa; Chan, Wai Chi; Ng, Roger Man Kin; Hung, Se Fong; Cheung, Eric Fuk Chi; Sham, Pak Chung; Chiu, Helen Fung Kum; Lam, Ming; Lee, Edwin Ho Ming; Chiang, Tin Po; Chan, Lap Kei; Lau, Gary Kar Wai; Lee, Allen Ting Chun; Leung, Grace Tak Yu; Leung, Joey Shuk Yan; Lau, Joseph Tak Fai; van Os, Jim; Lewis, Glyn; Bebbington, Paul

2017-10-21

Lifetime prevalence of psychotic disorders varies widely across studies. Epidemiological surveys have rarely examined prevalences of specific psychotic disorders other than schizophrenia, and the majority used a single-phase design without employing clinical reappraisal interview for diagnostic verification. The current study investigated lifetime prevalence, correlates and service utilization of schizophrenia-spectrum, affective, and other non-affective psychotic disorders in a representative sample of community-dwelling Chinese adult population aged 16-75 years (N = 5719) based on a territory-wide, population-based household survey for mental disorders in Hong Kong. The survey adopted a 2-phase design comprising first-phase psychosis screening and second-phase diagnostic verification incorporating clinical information from psychiatrist-administered semi-structured interview and medical record review to ascertain DSM-IV lifetime diagnosis for psychotic disorders. Data on sociodemographics, psychosocial characteristics and service utilization were collected. Our results showed that lifetime prevalence was 2.47% for psychotic disorder overall, 1.25% for schizophrenia, 0.15% for delusional disorder, 0.38% for psychotic disorder not otherwise specified, 0.31% for bipolar disorder with psychosis, and 0.33% for depressive disorder with psychosis. Schizophrenia-spectrum disorder was associated with family history of psychosis, cigarette smoking and variables indicating socioeconomic disadvantage. Victimization experiences were significantly related to affective psychoses and other non-affective psychoses. Around 80% of participants with any psychotic disorder sought some kind of professional help for mental health problems in the past year. Using comprehensive diagnostic assessment involving interview and record data, our results indicate that approximately 2.5% of Chinese adult population had lifetime psychotic disorder which represents a major public health concern. �

A systematic review on tobacco use among civilian populations affected by armed conflict.

PubMed

Lo, Janice; Patel, Preeti; Roberts, Bayard

2016-03-01

To systematically examine evidence on tobacco use among conflict-affected civilian populations. Primary quantitative and qualitative studies published in English up to April 2014. Bibliographic databases searched were EMBASE, Global Health, MEDLINE, PsycEXTRA, PsycINFO, Web of Science, Cochrane; with the main terms of: (Smoke*, tobacco*, cigarette*, nicotine, beedi, bidi, papirosi, dip, chew, snuff, snus, smokeless tobacco) AND (armed-conflict, conflict-affected, conflict, war, refugee, internally displaced, forcibly displaced, asylum, humanitarian). Grey literature was searched using humanitarian databases, websites and search engines. Studies were independently selected by two reviewers, with a study outcome of tobacco use and a population of conflict-affected civilian populations such as internally displaced persons, refugees, residents in conflict-affected areas, residents and returning forcibly displaced populations returning in stabilised and postconflict periods. 2863 studies were initially identified. Data were independently extracted. The Quality Assessment Tool for Quantitative Studies and the Critical Appraisal Skills Programme for qualitative studies were used to assess study quality. 39 studies met inclusion criteria and descriptive analysis was used. Findings were equivocal on the effect of conflict on tobacco use. Evidence was clearer on associations between post-traumatic stress and other mental disorders with nicotine dependence. However, there were too few studies for definitive conclusions. No study examined the effectiveness of tobacco-related interventions. The quantitative studies were moderate (N=13) or weak (N=22) quality, and qualitative studies were moderate (N=3) or strong (N=2). Some evidence indicates links between conflict and tobacco use but substantially more research is required. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Guar meal germ and hull fractions differently affect growth performance and intestinal viscosity of broiler chickens.

PubMed

Lee, J T; Bailey, C A; Cartwright, A L

2003-10-01

High concentrations of guar meal in poultry diets deleteriously affect growth, feed intake, and digesta viscosity. These effects are attributed to residual gum in the meal. A 2 x 5 factorial experiment investigated the impacts of two guar meal fractions (germ and hull) at five inclusion levels (0, 2.5, 5.0, 7.5, and 10.0%) on intestinal viscosity, measures of growth, and feed conversion in broiler chickens fed to 20 d of age. Growth and feed conversion ratio were not affected by inclusion of as much as 7.5% of the germ fraction into poultry diets, while inclusion of the hull fraction reduced growth at all concentrations. The hull fraction increased intestinal viscosity at all inclusion levels fed, although feed conversion was not affected until the inclusion rate exceeded 5.0%. The germ fraction significantly increased intestinal viscosity at 7.5 and 10% inclusion rates. When germ fraction was fed, relative organ weights remained constant through all concentrations except for the ventriculus and duodenum at 7.5 and 10% inclusion levels. Relative pancreas weight was significantly increased at the 10% level of the hull fraction. Increases in intestinal viscosity corresponded with growth depression. These results suggest that residual gum was responsible for some deleterious effects seen when guar meal was fed. The germ fraction was a superior ingredient when compared with the hull fraction. The guar meal germ fraction constituting as much as 7.5% of the diet supported growth and feed conversion measures similar to those observed with a typical corn-soybean poultry ration.

Periodic matrix population models: growth rate, basic reproduction number, and entropy.

PubMed

Bacaër, Nicolas

2009-10-01

This article considers three different aspects of periodic matrix population models. First, a formula for the sensitivity analysis of the growth rate lambda is obtained that is simpler than the one obtained by Caswell and Trevisan. Secondly, the formula for the basic reproduction number R0 in a constant environment is generalized to the case of a periodic environment. Some inequalities between lambda and R0 proved by Cushing and Zhou are also generalized to the periodic case. Finally, we add some remarks on Demetrius' notion of evolutionary entropy H and its relationship to the growth rate lambda in the periodic case.

Do plastic particles affect microalgal photosynthesis and growth?

PubMed

Sjollema, Sascha B; Redondo-Hasselerharm, Paula; Leslie, Heather A; Kraak, Michiel H S; Vethaak, A Dick

2016-01-01

The unbridled increase in plastic pollution of the world's oceans raises concerns about potential effects these materials may have on microalgae, which are primary producers at the basis of the food chain and a major global source of oxygen. Our current understanding about the potential modes and mechanisms of toxic action that plastic particles exert on microalgae is extremely limited. How effects might vary with particle size and the physico-chemical properties of the specific plastic material in question are equally unelucidated, but may hold clues to how toxicity, if observed, is exerted. In this study we selected polystyrene particles, both negatively charged and uncharged, and three different sizes (0.05, 0.5 and 6μm) for testing the effects of size and material properties. Microalgae were exposed to different polystyrene particle sizes and surface charges for 72h. Effects on microalgal photosynthesis and growth were determined by pulse amplitude modulation fluorometry and flow cytometry, respectively. None of the treatments tested in these experiments had an effect on microalgal photosynthesis. Microalgal growth was negatively affected (up to 45%) by uncharged polystyrene particles, but only at high concentrations (250mg/L). Additionally, these adverse effects were demonstrated to increase with decreasing particle size. Copyright © 2015 Elsevier B.V. All rights reserved.

Population Growth in New Hampshire during the Nineteenth and Twentieth Centuries. Studies in New England Geography, Number 1.

ERIC Educational Resources Information Center

Hobart, Christine L.

This paper traces the shifts in New Hampshire's state and county population during the nineteenth and twentieth centuries, focusing on the growth of urban centers and industry. From 1790 to 1840 most of New Hampshire's population growth was agricultural despite the beginnings of industrialization and urbanization. These processes greatly…

Global drought and severe drought-affected populations in 1.5 and 2 °C warmer worlds

NASA Astrophysics Data System (ADS)

Liu, Wenbin; Sun, Fubao; Lim, Wee Ho; Zhang, Jie; Wang, Hong; Shiogama, Hideo; Zhang, Yuqing

2018-03-01

The 2015 Paris Agreement proposed a more ambitious climate change mitigation target on limiting global warming to 1.5 °C instead of 2 °C above preindustrial levels. Scientific investigations on environmental risks associated with these warming targets are necessary to inform climate policymaking. Based on the Coupled Model Intercomparison Project phase 5 (CMIP5) climate models, we present the first risk-based assessment of changes in global drought and the impact of severe drought on populations from additional 1.5 and 2 °C warming conditions. Our results highlight the risk of drought on a global scale and in several hotspot regions such as the Amazon, northeastern Brazil, southern Africa and Central Europe at both 1.5 and 2 °C global warming relative to the historical period, showing increases in drought durations from 2.9 to 3.2 months. Correspondingly, more total and urban populations would be exposed to severe droughts globally (+132.5 ± 216.2 million and +194.5 ± 276.5 million total population and +350.2 ± 158.8 million and +410.7 ± 213.5 million urban populations in 1.5 and 2 °C warmer worlds) and regionally (e.g., East Africa, West Africa and South Asia). Less rural populations (-217.7 ± 79.2 million and -216.2 ± 82.4 million rural populations in 1.5 and 2 °C warmer worlds) would be exposed to severe drought globally under climate warming, population growth and especially the urbanization-induced population migration. By keeping global warming at 1.5 °C above the preindustrial levels instead of 2 °C, there is a decrease in drought risks (i.e., less drought duration, less drought intensity and severity but relatively more frequent drought) and the affected total, urban and rural populations would decrease globally and in most regions. While challenging for both East Africa and South Asia, the benefits of limiting warming to below 1.5 °C in terms of global drought risk and impact reduction are significant.

The effect of light direction and suspended cell concentrations on algal biofilm growth rates.

PubMed

Schnurr, Peter J; Espie, George S; Allen, D Grant

2014-10-01

Algae biofilms were grown in a semicontinuous flat plate biofilm photobioreactor to study the effects of light direction and suspended algal cell populations on algal biofilm growth. It was determined that, under the growth conditions and biofilm thicknesses studied, light direction had no effect on long-term algal biofilm growth (26 days); however, light direction did affect the concentration of suspended algal cells by influencing the photon flux density in the growth medium in the photobioreactors. This suspended algal cell population affected short-term (7 days) algae cell recruitment and algal biofilm growth, but additional studies showed that enhanced suspended algal cell populations did not affect biofilm growth rates over the long term (26 days). Studying profiles of light transmittance through biofilms as they grew showed that most of the light became attenuated by the biomass after just a few days of growth (88 % after 3 days). The estimated biofilm thicknesses after these few days of growth were approximately 150 μm. The light attenuation data suggests that, although the biofilms grew to 700-900 μm, under these light intensities, only the first few hundred micrometers of the biofilm is receiving enough light to be photosynthetically active. We postulate that this photosynthetically active layer of the biofilm grows adjacent to the light source, while the rest of the biofilm is in a stationary growth phase. The results of this study have implications for algal biofilm photobioreactor design and operation.

The Impact of Population Demography and Selection on the Genetic Architecture of Complex Traits

PubMed Central

Lohmueller, Kirk E.

2014-01-01

Population genetic studies have found evidence for dramatic population growth in recent human history. It is unclear how this recent population growth, combined with the effects of negative natural selection, has affected patterns of deleterious variation, as well as the number, frequency, and effect sizes of mutations that contribute risk to complex traits. Because researchers are performing exome sequencing studies aimed at uncovering the role of low-frequency variants in the risk of complex traits, this topic is of critical importance. Here I use simulations under population genetic models where a proportion of the heritability of the trait is accounted for by mutations in a subset of the exome. I show that recent population growth increases the proportion of nonsynonymous variants segregating in the population, but does not affect the genetic load relative to a population that did not expand. Under a model where a mutation's effect on a trait is correlated with its effect on fitness, rare variants explain a greater portion of the additive genetic variance of the trait in a population that has recently expanded than in a population that did not recently expand. Further, when using a single-marker test, for a given false-positive rate and sample size, recent population growth decreases the expected number of significant associations with the trait relative to the number detected in a population that did not expand. However, in a model where there is no correlation between a mutation's effect on fitness and the effect on the trait, common variants account for much of the additive genetic variance, regardless of demography. Moreover, here demography does not affect the number of significant associations detected. These findings suggest recent population history may be an important factor influencing the power of association tests and in accounting for the missing heritability of certain complex traits. PMID:24875776

Adult height variants affect birth length and growth rate in children.

PubMed

Paternoster, Lavinia; Howe, Laura D; Tilling, Kate; Weedon, Michael N; Freathy, Rachel M; Frayling, Timothy M; Kemp, John P; Smith, George Davey; Timpson, Nicholas J; Ring, Susan M; Evans, David M; Lawlor, Debbie A

2011-10-15

Previous studies identified 180 single nucleotide polymorphisms (SNPs) associated with adult height, explaining ∼10% of the variance. The age at which these begin to affect growth is unclear. We modelled the effect of these SNPs on birth length and childhood growth. A total of 7768 participants in the Avon Longitudinal Study of Parents and Children had data available. Individual growth trajectories from 0 to 10 years were estimated using mixed-effects linear spline models and differences in trajectories by individual SNPs and allelic score were determined. The allelic score was associated with birth length (0.026 cm increase per 'tall' allele, SE = 0.003, P = 1 × 10(-15), equivalent to 0.017 SD). There was little evidence of association between the allelic score and early infancy growth (0-3 months), but there was evidence of association between the allelic score and later growth. This association became stronger with each consecutive growth period, per 'tall' allele per month effects were 0.015 SD (3 months-1 year, SE = 0.004), 0.023 SD (1-3 years, SE = 0.003) and 0.028 SD (3-10 years, SE = 0.003). By age 10, the mean height difference between individuals with ≤170 versus ≥191 'tall' alleles (the top and bottom 10%) was 4.7 cm (0.8 SD), explaining ∼5% of the variance. There was evidence of associations with specific growth periods for some SNPs (rs3791675, EFEMP1 and rs6569648, L3MBTL3) and supportive evidence for previously reported age-dependent effects of HHIP and SOCS2 SNPs. SNPs associated with adult height influence birth length and have an increasing effect on growth from late infancy through to late childhood. By age 10, they explain half the height variance (∼5%) of that explained in adults (∼10%).

Age, growth and population structure of invasive lionfish (Pterois volitans/miles) in northeast Florida using a length-based, age-structured population model.

PubMed

Johnson, Eric G; Swenarton, Mary Katherine

2016-01-01

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.

Age, growth and population structure of invasive lionfish (Pterois volitans/miles) in northeast Florida using a length-based, age-structured population model

PubMed Central

2016-01-01

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. PMID:27920953

Social policy and population growth in South-East Asia.

PubMed

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.

Reproductive health, population growth, economic development and environmental change.

PubMed

Lincoln, D W

1993-01-01

World population will increase by 1000 million, or by 20%, within 10 years. Ninety-five per cent of this increase will occur in the South, in areas that are already economically, environmentally and politically fragile. Morbidity and mortality associated with reproduction will be greater in the current decade than in any period in human history. Annually, 40-60 million pregnancies will be terminated and 5-10 million children will die within one year of birth. AIDS-related infections, e.g. tuberculosis, will undermine health care in Africa (and elsewhere) and in places AIDS-related deaths will decimate the work-force. The growth in population and associated morbidity will inhibit global economic development and spawn new problems. The key issues are migration, the spread of disease, the supply of water and the degradation of land, and fiscal policies with respect to family planning, pharmaceuticals and Third-World debt. Full education, particularly of women, and more effective family planning in the South have the power to unlock the problem. Failure will see the developed countries, with their 800 million population, swamped by the health, economic and environmental problems of the South, with its projected population of 5400 million people for the year 2000.

Recent range expansion of a terrestrial orchid corresponds with climate-driven variation in its population dynamics.

PubMed

van der Meer, Sascha; Jacquemyn, Hans; Carey, Peter D; Jongejans, Eelke

2016-06-01

The population dynamics and distribution limits of plant species are predicted to change as the climate changes. However, it remains unclear to what extent climate variables affect population dynamics, which vital rates are most sensitive to climate change, and whether the same vital rates drive population dynamics in different populations. In this study, we used long-term demographic data from two populations of the terrestrial orchid Himantoglossum hircinum growing at the northern edge of their geographic range to quantify the influence of climate change on demographic vital rates. Integral projection models were constructed to study how climate conditions between 1991 and 2006 affected population dynamics and to assess how projected future climate change will affect the long-term viability of this species. Based on the parameterised vital rate functions and the observed climatic conditions, one of the studied populations had an average population growth rate above 1 (λ = 1.04), while the other was declining at ca. 3 % year(-1) (λ = 0.97). Variation in temperature and precipitation mainly affected population growth through their effect on survival and fecundity. Based on UK Climate Projection 2009 estimates of future climate conditions for three greenhouse gas emission scenarios, population growth rates are expected to increase in one of the studied populations. Overall, our results indicate that the observed changes in climatic conditions appeared to be beneficial to the long-term survival of the species in the UK and suggest that they may have been the driving force behind the current range expansion of H. hircinum in England.

Identification and synthetic modeling of factors affecting American black duck populations

USGS Publications Warehouse

Conroy, Michael J.; Miller, Mark W.; Hines, James E.

2002-01-01

We reviewed the literature on factors potentially affecting the population status of American black ducks (Anas rupribes). Our review suggests that there is some support for the influence of 4 major, continental-scope factors in limiting or regulating black duck populations: 1) loss in the quantity or quality of breeding habitats; 2) loss in the quantity or quality of wintering habitats; 3) harvest, and 4) interactions (competition, hybridization) with mallards (Anas platyrhychos) during the breeding and/or wintering periods. These factors were used as the basis of an annual life cycle model in which reproduction rates and survival rates were modeled as functions of the above factors, with parameters of the model describing the strength of these relationships. Variation in the model parameter values allows for consideration of scientific uncertainty as to the degree each of these factors may be contributing to declines in black duck populations, and thus allows for the investigation of the possible effects of management (e.g., habitat improvement, harvest reductions) under different assumptions. We then used available, historical data on black duck populations (abundance, annual reproduction rates, and survival rates) and possible driving factors (trends in breeding and wintering habitats, harvest rates, and abundance of mallards) to estimate model parameters. Our estimated reproduction submodel included parameters describing negative density feedback of black ducks, positive influence of breeding habitat, and negative influence of mallard densities; our survival submodel included terms for positive influence of winter habitat on reproduction rates, and negative influences of black duck density (i.e., compensation to harvest mortality). Individual models within each group (reproduction, survival) involved various combinations of these factors, and each was given an information theoretic weight for use in subsequent prediction. The reproduction model with highest

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

PubMed

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.

Innovation and the growth of human population.

PubMed

Weinberger, V P; Quiñinao, C; Marquet, P A

2017-12-05

Biodiversity is sustained by and is essential to the services that ecosystems provide. Different species would use these services in different ways, or adaptive strategies, which are sustained in time by continuous innovations. Using this framework, we postulate a model for a biological species ( Homo sapiens ) in a finite world where innovations, aimed at increasing the flux of ecosystem services (a measure of habitat quality), increase with population size, and have positive effects on the generation of new innovations (positive feedback) as well as costs in terms of negatively affecting the provision of ecosystem services. We applied this model to human populations, where technological innovations are driven by cumulative cultural evolution. Our model shows that depending on the net impact of a technology on the provision of ecosystem services ( θ ), and the strength of technological feedback ( ξ ), different regimes can result. Among them, the human population can fill the entire planet while maximizing their well-being, but not exhaust ecosystem services. However, this outcome requires positive or green technologies that increase the provision of ecosystem services with few negative externalities or environmental costs, and that have a strong positive feedback in generating new technologies of the same kind. If the feedback is small, then the technological stock can collapse together with the human population. Scenarios where technological innovations generate net negative impacts may be associated with a limited technological stock as well as a limited human population at equilibrium and the potential for collapse. The only way to fill the planet with humans under this scenario of negative technologies is by reducing the technological stock to a minimum. Otherwise, the only feasible equilibrium is associated with population collapse. Our model points out that technological innovations per se may not help humans to grow and dominate the planet. Instead

A systematic review of measures of HIV/AIDS stigma in paediatric HIV-infected and HIV-affected populations

PubMed Central

McAteer, Carole Ian; Truong, Nhan-Ai Thi; Aluoch, Josephine; Deathe, Andrew Roland; Nyandiko, Winstone M; Marete, Irene; Vreeman, Rachel Christine

2016-01-01

Introduction HIV-related stigma impacts the quality of life and care management of HIV-infected and HIV-affected individuals, but how we measure stigma and its impact on children and adolescents has less often been described. Methods We conducted a systematic review of studies that measured HIV-related stigma with a quantitative tool in paediatric HIV-infected and HIV-affected populations. Results and discussion Varying measures have been used to assess stigma in paediatric populations, with most studies utilizing the full or variant form of the HIV Stigma Scale that has been validated in adult populations and utilized with paediatric populations in Africa, Asia and the United States. Other common measures included the Perceived Public Stigma Against Children Affected by HIV, primarily utilized and validated in China. Few studies implored item validation techniques with the population of interest, although scales were used in a different cultural context from the origin of the scale. Conclusions Many stigma measures have been used to assess HIV stigma in paediatric populations, globally, but few have implored methods for cultural adaptation and content validity. PMID:27717409

A systematic review of measures of HIV/AIDS stigma in paediatric HIV-infected and HIV-affected populations.

PubMed

McAteer, Carole Ian; Truong, Nhan-Ai Thi; Aluoch, Josephine; Deathe, Andrew Roland; Nyandiko, Winstone M; Marete, Irene; Vreeman, Rachel Christine

2016-01-01

HIV-related stigma impacts the quality of life and care management of HIV-infected and HIV-affected individuals, but how we measure stigma and its impact on children and adolescents has less often been described. We conducted a systematic review of studies that measured HIV-related stigma with a quantitative tool in paediatric HIV-infected and HIV-affected populations. Varying measures have been used to assess stigma in paediatric populations, with most studies utilizing the full or variant form of the HIV Stigma Scale that has been validated in adult populations and utilized with paediatric populations in Africa, Asia and the United States. Other common measures included the Perceived Public Stigma Against Children Affected by HIV, primarily utilized and validated in China. Few studies implored item validation techniques with the population of interest, although scales were used in a different cultural context from the origin of the scale. Many stigma measures have been used to assess HIV stigma in paediatric populations, globally, but few have implored methods for cultural adaptation and content validity.

Genetic variation in Pinus strobiformis growth and drought tolerance from southwestern US populations.

PubMed

Goodrich, Betsy A; Waring, Kristen M; Kolb, Thomas E

2016-10-01

The persistence of some tree species is threatened by combinations of novel abiotic and biotic stressors. To examine the hypothesis that Pinus strobiformis Engelm., a tree threatened by an invasive forest pathogen and a changing climate, exhibits intraspecific genetic variation in adaptive traits, we conducted a common garden study of seedlings at one location with two watering regimes using 24 populations. Four key findings emerged: (i) growth and physiological traits were low to moderately differentiated among populations but differentiation was high for some traits in water-stressed populations; (ii) seedlings from warmer climates grew larger, had higher stomatal density and were more water-use efficient (as measured by the carbon isotope ratio) than populations from colder climates; (iii) seedlings from the northern edge of the species' distribution had lower water-use efficiency, higher stomatal conductance, slower growth and longer survival in a lethal drought experiment compared with seedlings from more southern populations; and (iv) based on non-metric multidimensional scaling analyses, populations clustered into southern and northern groups, which did not correspond to current seed transfer zones. Our discovery of a clinal geographic pattern of genetic variation in adaptive traits of P. strobiformis seedlings will be useful in developing strategies to maintain the species during ongoing climate change and in the face of an invasive pathogen. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Population ecology of the gulf ribbed mussel across a salinity gradient: recruitment, growth and density

USGS Publications Warehouse

Honig, Aaron; Supan, John; LaPeyre, Megan K.

2015-01-01

Benthic intertidal bivalves play an essential role in estuarine ecosystems by contributing to habitat provision, water filtration, and promoting productivity. As such, changes that impact population distributions and persistence of local bivalve populations may have large ecosystem level consequences. Recruitment, growth, mortality, population size structure and density of the gulf coast ribbed mussel, Geukensia granosissima, were examined across a salinity gradient in southeastern Louisiana. Data were collected along 100-m transects at interior and edge marsh plots located at duplicate sites in upper (salinity ~4 psu), central (salinity ~8 psu) and lower (salinity ~15 psu) Barataria Bay, Louisiana, U.S.A. Growth, mortality and recruitment were measured in established plots from April through November 2012. Mussel densities were greatest within the middle bay (salinity ~8) regardless of flooding regime, but strongly associated with highest stem densities of Juncus roemerianus vegetation. Mussel recruitment, growth, size and survival were significantly higher at mid and high salinity marsh edge sites as compared to all interior marsh and low salinity sites. The observed patterns of density, growth and mortality in Barataria Bay may reflect detrital food resource availability, host vegetation community distribution along the salinity gradient, salinity tolerance of the mussel, and reduced predation at higher salinity edge sites.

Global Population Growth: 21st Century Challenges. Headline Series No. 302.

ERIC Educational Resources Information Center

Moffett, George D.

This booklet examines the highly complex and highly nuanced subject of population growth and its consequences. The subject is controversial because it lies at the intersection of so many different disciplines. The primary purpose of the book is to define the large measure of common ground that exists among experts with respect to two critical…

Soil type affects Pinus ponderosa var. scopulorum (Pinaceae) seedling growth in simulated drought experiments.

PubMed

Lindsey, Alexander J; Kilgore, Jason S

2013-08-01

Effects of drought stress and media type interactions on growth of Pinus ponderosa var. scopulorum germinants were investigated. • Soil properties and growth responses under drought were compared across four growth media types: two native soils (dolomitic limestone and granite), a soil-less industry standard conifer medium, and a custom-mixed conifer medium. After 35 d of growth, the seedlings under drought stress (reduced watering) produced less shoot and root biomass than watered control seedlings. Organic media led to decreased root biomass, but increased root length and shoot biomass relative to the mineral soils. • Media type affected root-to-shoot biomass partitioning of P. ponderosa var. scopulorum, which may influence net photosynthetic rates, growth, and long-term seedling survival. Further work should examine how specific soil properties like bulk density and organic matter influence biomass allocation in greenhouse studies.

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

USGS Publications Warehouse

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

Exploring posttraumatic growth in Tamil children affected by the Indian Ocean Tsunami in 2004.

PubMed

Exenberger, Silvia; Ramalingam, Panch; Höfer, Stefan

2016-10-13

Few studies explore posttraumatic growth (PTG) in children from Eastern cultures. To help address this gap, the present study examined PTG among 177 South Indian children aged 8-17 years who were affected by the 2004 Tsunami. The study identifies the underlying factor structure of the Tamil version of the Revised Posttraumatic Growth Inventory for Children (PTGI-C-R), and aims to explore the prevalence of PTG, the relationship between distress and growth, and gender and age differences in PTG. The results of the principal component analysis indicated a two-factor structure with an interpersonal and a person-centred dimension of growth. The total scores of the Tamil PTGI-C-R were positively associated with posttraumatic stress symptoms (PTSS) and age. Moreover, there was a significant relationship between age and the person-centred growth subscale. Non-parametric tests found no gender differences in perceived growth. The role of socio-cultural factors on the nature of PTG is discussed. © 2016 International Union of Psychological Science.

The third population boom and corresponding macro-policies.

PubMed

Tian, X

1990-01-01

China's birth peak between 1962-1973, and the expected 3rd peak beginning in 1986 has and will create a need for better, stable family planning measures; economic planning between 1990 and 2020 needs to accommodate the working population which in 2010 is expected to be 71.4% of the population (956 million); and a macro-strategic policy needs to be developed of the elderly who may constitute 17.44% of the population. The aging trend in China's working age population is expected to rise so rapidly that in 48 years, between 1982 and 2040, the over 65 population will quadruple ( a process in developed countries usually taking 80 years), thus creating a significant impact on a society with a low level of economic development. It is suggested that along with the growth in the national economy should come a state-provided welfare and retirement system, with reforms necessary to generate the additional income for elderly support; it is important that the cultural pattern of family care of the elderly remain intact. Assisting the able elderly in earning income in the service sector is encouraged. China's population has historically undergone 2 peak growth periods, between 1685 and 1830 with a 1% growth rate and between 1949-89 with an annual growth rate of 1.8%. The 2nd period is marked by 2 smaller peaks, one between 1953- 1957 with a growth rate of 2.38% and 1962-73 with a growth rate of 2.56%. A decline after 1974 changed to another upward cycle in 1986 with an increase to a 1.43 % growth rate expected to continue to 1996. The 1st peak between 1953-57 has already affected population control and the job market, and the fecund population is of concern because of the absolute size of the population, and because the planned limit for population growth of 1.2 billion by the year 2000 may be exceeded; and the projected rates, which have been increasing as expected, mean a population of 1.5 billion by 2050.

Body downsizing caused by non-consumptive social stress severely depresses population growth rate

PubMed Central

Edeline, Eric; Haugen, Thrond O.; Weltzien, Finn-Arne; Claessen, David; Winfield, Ian J.; Stenseth, Nils Chr.; Vøllestad, L. Asbjørn

2010-01-01

Chronic social stress diverts energy away from growth, reproduction and immunity, and is thus a potential driver of population dynamics. However, the effects of social stress on demographic density dependence remain largely overlooked in ecological theory. Here we combine behavioural experiments, physiology and population modelling to show in a top predator (pike Esox lucius) that social stress alone may be a primary driver of demographic density dependence. Doubling pike density in experimental ponds under controlled prey availability did not significantly change prey intake by pike (i.e. did not significantly change interference or exploitative competition), but induced a neuroendocrine stress response reflecting a size-dependent dominance hierarchy, depressed pike energetic status and lowered pike body growth rate by 23 per cent. Assuming fixed size-dependent survival and fecundity functions parameterized for the Windermere (UK) pike population, stress-induced smaller body size shifts age-specific survival rates and lowers age-specific fecundity, which in Leslie matrices projects into reduced population rate of increase (λ) by 37–56%. Our models also predict that social stress flattens elasticity profiles of λ to age-specific survival and fecundity, thus making population persistence more dependent on old individuals. Our results suggest that accounting for non-consumptive social stress from competitors and predators is necessary to accurately understand, predict and manage food-web dynamics. PMID:19923130

Sociality, individual fitness and population dynamics of yellow-bellied marmots.

PubMed

Armitage, Kenneth B

2012-02-01

Social behaviour was proposed as a density-dependent intrinsic mechanism that could regulate an animal population by affecting reproduction and dispersal. Populations of the polygynous yellow-bellied marmot (Marmota flaviventris) fluctuate widely from year to year primarily driven by the number of weaned young. The temporal variation in projected population growth rate was driven mainly by changes in the age of first reproduction and fertility, which are affected by reproductive suppression. Dispersal is unrelated to population density, or the presence of the father; hence, neither of these limits population growth or acts as an intrinsic mechanism of population regulation; overall, intrinsic regulation seems unlikely. Sociality affects the likelihood of reproduction in that the annual probability of reproducing and the lifetime number of offspring are decreased by the number of older females and by the number of same-aged females present, but are increased by the number of younger adult females present. Recruitment of a yearling female is most likely when her mother is present; recruitment of philopatric females is much more important than immigration for increasing the number of adult female residents. Predation and overwinter mortality are the major factors limiting the number of resident adults. Social behaviour is not directed towards population regulation, but is best interpreted as functioning to maximize direct fitness. © 2011 Blackwell Publishing Ltd.

Population growth and rural-urban migration, with special reference to Ghana.

PubMed

De Graft-johnson, K T

1974-01-01

While the population of Ghana is expected to double in 25 years at the current rate of increase (approximately 2.5% per annum), the population of urban centers is increasing even faster. The 1970 census shows the urban population growing by 4.8% per annum. This is mainly the result of rural to urban migration and, to a smaller extent, the increase in the number of urban centers from 39 in 1948 to 98 in 1960 to 135 in 1970. In the 1970 census only 57.1% of the population were enumerated in their locality of birth and only 20.9% in a locality other than their place of birth but in the same region. 4.1% were born outside Ghana, mostly in another West African country. 1 striking difference between urban and rural areas is the differing sex ratio of the working population. In rural areas there are 91.0 males aged 15-64 years for every 100 females while in urban areas there are 107.1. Most migration in Africa is for employment and those most likely to migrate are working-age males. Because secondary schools are scarce in rural areas, urban dwellers generally have a higher education level. There are no significant differences between overall labor force participation rates for females. The nationwide participation rate was 38.9% for both males and females (males 43.8%, females 34.1%); in urban areas the total was 40.0% (males 46.3%, females 33.7%) and in rural areas 38.5% (males 42.7%, females 34.3%). Ghanaian women have traditionally occupied a prominent place in the labor force. The theory that urban migration is due to urban-rural income disparities is not confirmed by figures. Considering the high amount of unemployment in urban areas, a rural dweller can average as much as a city dweller. In fact, poorly educated migrants are the ones most affected by urban unemployment. A recent study by Kodwo Ewusi considered the impact of many variables on migration; he found depressed social conditions at the place of origin are more compelling motivations than economic factors

Customized versus population-based growth curves: prediction of low body fat percent at term corrected gestational age following preterm birth.

PubMed

Law, Tameeka L; Katikaneni, Lakshmi D; Taylor, Sarah N; Korte, Jeffrey E; Ebeling, Myla D; Wagner, Carol L; Newman, Roger B

2012-07-01

Compare customized versus population-based growth curves for identification of small-for-gestational-age (SGA) and body fat percent (BF%) among preterm infants. Prospective cohort study of 204 preterm infants classified as SGA or appropriate-for-gestational-age (AGA) by population-based and customized growth curves. BF% was determined by air-displacement plethysmography. Differences between groups were compared using bivariable and multivariable linear and logistic regression analyses. Customized curves reclassified 30% of the preterm infants as SGA. SGA infants identified by customized method only had significantly lower BF% (13.8 ± 6.0) than the AGA (16.2 ± 6.3, p = 0.02) infants and similar to the SGA infants classified by both methods (14.6 ± 6.7, p = 0.51). Customized growth curves were a significant predictor of BF% (p = 0.02), whereas population-based growth curves were not a significant independent predictor of BF% (p = 0.50) at term corrected gestational age. Customized growth potential improves the differentiation of SGA infants and low BF% compared with a standard population-based growth curve among a cohort of preterm infants.

Bone growth, limb proportions and non-specific stress in archaeological populations from Croatia.

PubMed

Pinhasi, R; Timpson, A; Thomas, M; Slaus, M

2014-01-01

The effect of environmental factors and, in particular, non-specific stress on the growth patterns of limbs and other body dimensions of children from past populations is not well understood. This study assesses whether growth of mediaeval and post-mediaeval children aged between 0-11.5 years from Adriatic (coastal) and continental Croatia varies by region and by the prevalence and type of non-specific stress. Dental ages were estimated using the Moorrees, Fanning and Hunt (MFH) scoring method. Growth of long bone diaphyses (femur, tibia, humerus, radius and ulna) was assessed by using a composite Z-score statistic (CZS). Clavicular length was measured as a proxy for upper trunk width, distal metaphyseal width of the femur was measured as a proxy for body mass and upper and lower intra-limb indices were calculated. Differences between sub-sets sampled by (a) region and (b) active vs healed non-specific stress indicators and (c) intra-limb indices were tested by Mann--Whitney U-tests and Analysis of Covariance (ANCOVA). Adriatic children attained larger dimensions-per-age than continental children. Children with healed stress lesions had larger dimensions-per-age than those with active lesions. No inter-regional difference was found in intra-limb indices. These findings highlight the complexity of growth patterns in past populations and indicate that variation in environmental conditions such as diet and differences in the nature of non-specific stress lesions both exert a significant effect on long bone growth.

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

PubMed Central

Struchiner, Claudio Jose; Rocklöv, Joacim; Wilder-Smith, Annelies; Massad, Eduardo

2015-01-01

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. PMID:26322517

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

PubMed

Struchiner, Claudio Jose; Rocklöv, Joacim; Wilder-Smith, Annelies; Massad, Eduardo

2015-01-01

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.

Impacts of invasive fish removal through angling on population characteristics and juvenile growth rate.

PubMed

Evangelista, Charlotte; Britton, Robert J; Cucherousset, Julien

2015-06-01

Exploitation can modify the characteristics of fish populations through the selective harvesting of individuals, with this potentially leading to rapid ecological and evolutionary changes. Despite the well-known effects of invasive fishes on aquatic ecosystems generally, the potential effects of their selective removal through angling, a strategy commonly used to manage invasive fish, are poorly understood. The aim of this field-based study was to use the North American pumpkinseed Lepomis gibbosus as the model species to investigate the consequences of selective removal on their population characteristics and juvenile growth rates across 10 populations in artificial lakes in southern France. We found that the maximal individual mass in populations decreased as removal pressure through angling increased, whereas we did not observed any changes in the maximal individual length in populations as removal pressure increased. Total population abundance did not decrease as removal pressure increased; instead, here was a U-shaped relationship between removal pressure and the abundance of medium-bodied individuals. In addition, population biomass had a U-shaped curve response to removal pressure, implying that invasive fish populations can modulate their characteristics to compensate for the negative effects of selective removals. In addition, individual lengths at age 2 and juvenile growth rates decreased as removal pressure through angling increased, suggesting a shift toward an earlier size at maturity and an overall slower growing phenotype. Therefore, these outputs challenge the efficiency of selective management methods, suggesting the use of more proactive strategies to control invasive populations, and the need to investigate the potential ecological and evolutionary repercussions of nonrandom removal.

Impacts of invasive fish removal through angling on population characteristics and juvenile growth rate

PubMed Central

Evangelista, Charlotte; Britton, Robert J; Cucherousset, Julien

2015-01-01

Exploitation can modify the characteristics of fish populations through the selective harvesting of individuals, with this potentially leading to rapid ecological and evolutionary changes. Despite the well-known effects of invasive fishes on aquatic ecosystems generally, the potential effects of their selective removal through angling, a strategy commonly used to manage invasive fish, are poorly understood. The aim of this field-based study was to use the North American pumpkinseed Lepomis gibbosus as the model species to investigate the consequences of selective removal on their population characteristics and juvenile growth rates across 10 populations in artificial lakes in southern France. We found that the maximal individual mass in populations decreased as removal pressure through angling increased, whereas we did not observed any changes in the maximal individual length in populations as removal pressure increased. Total population abundance did not decrease as removal pressure increased; instead, here was a U-shaped relationship between removal pressure and the abundance of medium-bodied individuals. In addition, population biomass had a U-shaped curve response to removal pressure, implying that invasive fish populations can modulate their characteristics to compensate for the negative effects of selective removals. In addition, individual lengths at age 2 and juvenile growth rates decreased as removal pressure through angling increased, suggesting a shift toward an earlier size at maturity and an overall slower growing phenotype. Therefore, these outputs challenge the efficiency of selective management methods, suggesting the use of more proactive strategies to control invasive populations, and the need to investigate the potential ecological and evolutionary repercussions of nonrandom removal. PMID:26078856

Conspecific and not performance-based attraction on immigrants drives colony growth in a waterbird.

PubMed

Tenan, Simone; Fasola, Mauro; Volponi, Stefano; Tavecchia, Giacomo

2017-09-01

Local recruitment and immigration play an important part in the dynamics and growth of animal populations. However, their estimation and incorporation into open population models is, in most cases, problematic. We studied factors affecting the growth of a recently established colony of Eurasian spoonbill (Platalea leucorodia) and assessed the contribution of local recruits, i.e. birds born in the colony, and immigrants, i.e. birds of unknown origin, to colony growth. We applied an integrated population model that accounts for uncertainty in breeding state assignment and merges population surveys, local fecundity and individual longitudinal data of breeding and non-breeding birds, to estimate demographic rates and the relative role of recruitment and immigration in driving the local dynamics. We also used this analytical framework to assess the degree of support for the 'performance-based' and 'conspecific attraction' hypotheses as possible mechanisms of colony growth. Among the demographic rates, only immigration was positively and significantly correlated with population growth rate. In addition, the number of immigrants settling in the colony was positively correlated with colony size in the previous and current year, but was not correlated with fecundity of the previous year. Our results suggest that the variation in immigration affected colony dynamics and that conspecific attraction likely triggered the relevant role of immigration in the growth of a recently formed waterbird colony, supporting the need of including immigration in population analysis. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

Guide to Population Issues for Students and Teachers [and] Curriculum Guide.

ERIC Educational Resources Information Center

Facing the Future, Lopez Island, WA.

As the world grapples with increasing environmental, social, and security problems, population is rarely considered a cause or contributing factor. The relationship of population to the human condition, and to the condition of the Earth, is often subtle and complex. But population growth affects almost every aspect of life from education to…

Stochastic resonance in a generalized Von Foerster population growth model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumi, N.; Mankin, R.

The stochastic dynamics of a population growth model, similar to the Von Foerster model for human population, is studied. The influence of fluctuating environment on the carrying capacity is modeled as a multiplicative dichotomous noise. It is established that an interplay between nonlinearity and environmental fluctuations can cause single unidirectional discontinuous transitions of the mean population size versus the noise amplitude, i.e., an increase of noise amplitude can induce a jump from a state with a moderate number of individuals to that with a very large number, while by decreasing the noise amplitude an opposite transition cannot be effected. Anmore » analytical expression of the mean escape time for such transitions is found. Particularly, it is shown that the mean transition time exhibits a strong minimum at intermediate values of noise correlation time, i.e., the phenomenon of stochastic resonance occurs. Applications of the results in ecology are also discussed.« less

Estimating the effects of 17α-ethinylestradiol on stochastic population growth rate of fathead minnows: a population synthesis of empirically derived vital rates

USGS Publications Warehouse

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.

Estimating the effects of 17α-ethinylestradiol on stochastic population growth rate of fathead minnows: a population synthesis of empirically derived vital rates.

PubMed

Schwindt, Adam R; Winkelman, Dana L

2016-09-01

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.

Effect of autochthonous bacteriocin-producing Lactococcus lactis on bacterial population dynamics and growth of halotolerant bacteria in Brazilian charqui.

PubMed

Biscola, Vanessa; Abriouel, Hikmate; Todorov, Svetoslav Dimitrov; Capuano, Verena Sant'Anna Cabral; Gálvez, Antonio; Franco, Bernadette Dora Gombossy de Melo

2014-12-01

Charqui is a fermented, salted and sun-dried meat product, widely consumed in Brazil and exported to several countries. Growth of microorganisms in this product is unlikely due to reduced Aw, but halophilic and halotolerant bacteria may grow and cause spoilage. Charqui is a good source of lactic acid bacteria able to produce antimicrobial bacteriocins. In this study, an autochthonous bacteriocinogenic strain (Lactococcus lactis subsp. lactis 69), isolated from charqui, was added to the meat used for charqui manufacture and evaluated for its capability to prevent the growth of spoilage bacteria during storage up to 45 days. The influence of L. lactis 69 on the bacterial diversity during the manufacturing of the product was also studied, using denaturing gradient gel electrophoresis (DGGE). L. lactis 69 did not affect the counts and diversity of lactic acid bacteria during manufacturing and storage, but influenced negatively the populations of halotolerant microorganisms, reducing the spoilage potential. The majority of tested virulence genes was absent, evidencing the safety and potential technological application of this strain as an additional hurdle to inhibit undesirable microbial growth in this and similar fermented meat products. Copyright © 2014 Elsevier Ltd. All rights reserved.

Population Problems: A Constituent of General Culture in the 21st Century.

ERIC Educational Resources Information Center

Rath, Ferdinand J. C. M.

1993-01-01

Compares modern population problems with those of previous generations. Examines variations in population problems in different countries and world regions and the ways in which demographic events (e.g., rapid population growth or urbanization) in one region affect other regions. Advocates preparing for demographic changes through education. (DMM)

Harvest residue and competing vegetation affect soil moisture, soil temperature, N availability, and Douglas-fir seedling growth.

Treesearch

Scott D. Roberts; Constance A. Harrington; Thomas A. Terry

2005-01-01

Decisions made during stand regeneration that affect subsequent levels of competing vegetation and residual biomass can have important short-term consequences for early stand growth, and may affect long-term site productivity. Competing vegetation clearly affects the availability of site resources such as soil moisture and nutrients. Harvest residues can also impact...

Growth of non-Saccharomyces yeasts affects nutrient availability for Saccharomyces cerevisiae during wine fermentation.

PubMed

Medina, Karina; Boido, Eduardo; Dellacassa, Eduardo; Carrau, Francisco

2012-07-02

Yeast produces numerous secondary metabolites during fermentation that impact final wine quality. Although it is widely recognized that growth of diverse non-Saccharomyces (NS) yeast can positively affect flavor complexity during Saccharomyces cerevisiae wine fermentation, the inability to control spontaneous or co-fermentation processes by NS yeast has restricted their use in winemaking. We selected two NS yeasts from our Uruguayan native collection to study NS-S. cerevisiae interactions during wine fermentation. The selected strains of Hanseniaspora vineae and Metschnikowia pulcherrima had different yeast assimilable nitrogen consumption profiles and had different effects on S. cerevisiae fermentation and growth kinetics. Studies in which we varied inoculum size and using either simultaneous or sequential inoculation of NS yeast and S. cerevisiae suggested that competition for nutrients had a significant effect on fermentation kinetics. Sluggish fermentations were more pronounced when S. cerevisiae was inoculated 24h after the initial stage of fermentation with a NS strain compared to co-inoculation. Monitoring strain populations using differential WL nutrient agar medium and fermentation kinetics of mixed cultures allowed for a better understanding of strain interactions and nutrient addition effects. Limitation of nutrient availability for S. cerevisiae was shown to result in stuck fermentations as well as to reduce sensory desirability of the resulting wine. Addition of diammonium phosphate (DAP) and a vitamin mix to a defined medium allowed for a comparison of nutrient competition between strains. Addition of DAP and the vitamin mix was most effective in preventing stuck fermentations. Copyright © 2012 Elsevier B.V. All rights reserved.

Stage-Structured Population Dynamics of AEDES AEGYPTI

NASA Astrophysics Data System (ADS)

Yusoff, Nuraini; Budin, Harun; Ismail, Salemah

Aedes aegypti is the main vector in the transmission of dengue fever, a vector-borne disease affecting world population living in tropical and sub-tropical countries. Better understanding of the dynamics of its population growth will help in the efforts of controlling the spread of this disease. In looking at the population dynamics of Aedes aegypti, this paper explored the stage-structured modeling of the population growth of the mosquito using the matrix population model. The life cycle of the mosquito was divided into five stages: eggs, larvae, pupae, adult1 and adult2. Developmental rates were obtained for the average Malaysian temperature and these were used in constructing the transition matrix for the matrix model. The model, which was based only on temperature, projected that the population of Aedes aegypti will blow up with time, which is not realistic. For further work, other factors need to be taken into account to obtain a more realistic result.

Rodent malaria-resistant strains of the mosquito, Anopheles gambiae, have slower population growth than -susceptible strains

PubMed Central

Voordouw, Maarten J; Anholt, Bradley R; Taylor, Pam J; Hurd, Hilary

2009-01-01

Background Trade-offs between anti-parasite defence mechanisms and other life history traits limit the evolution of host resistance to parasites and have important implications for understanding diseases such as malaria. Mosquitoes have not evolved complete resistance to malaria parasites and one hypothesis is that anti-malaria defence mechanisms are costly. Results We used matrix population models to compare the population growth rates among lines of Anopheles gambiae that had been selected for resistance or high susceptibility to the rodent malaria parasite, Plasmodium yoelii nigeriensis. The population growth rate of the resistant line was significantly lower than that of the highly susceptible and the unselected control lines, regardless of whether mosquitoes were infected with Plasmodium or not. The lower population growth of malaria-resistant mosquitoes was caused by reduced post blood-feeding survival of females and poor egg hatching. Conclusion With respect to eradicating malaria, the strategy of releasing Plasmodium-resistant Anopheles mosquitoes is unlikely to be successful if the costs of Plasmodium-resistance in the field are as great as the ones measured in this study. High densities of malaria-resistant mosquitoes would have to be maintained by continuous release from captive breeding facilities. PMID:19379508

Energetics of growth and reproduction in a high-tidal population of the clam Ruditapes decussatus from Urdaibai Estuary (Basque Country, N. Spain)

NASA Astrophysics Data System (ADS)

Urrutia, M. B.; Ibarrola, I.; Iglesias, J. I. P.; Navarro, E.

1999-08-01

Energetics of growth and reproduction were studied in a high-tidal population of the clam Ruditapes decussatus living in the Mundaka Estuary in the Biosphere Reserve of Urdaibai (Basque Country, North Spain). The study included an analysis of growth rings on the shells to establish the growth curve as well as seasonal patterns of growth and body condition, and estimates of the breeding cycle including quantification of the reproductive output and reproductive effort. The simultaneous determination of the seasonal course of metabolism allowed estimates of assimilation, growth efficiency and reproductive costs. Growth rates were consistently lower in this population than in other populations from similar latitudes, and this effect is interpreted in terms of nutritional restrictions caused by the high tidal position of the population. Assimilation rapidly increased from March to July, as a consequence of optimal nutritional conditions and increasing water temperatures. Somatic growth (spring) and gonadal development (early summer) both took place during this period. Negative growth was restricted to the winter and late summer and was associated with poor nutritional conditions (winter) and high rates of metabolic expenditure induced by high temperatures (late summer). Net growth efficiencies (ranging from 27% in 1-y-old to 6% in 7-y-old individuals) ranked among the lowest recorded for populations of marine bivalves. Reduced reproductive-effort values were consistent with the poor growing conditions that appeared to characterise this population of clams.

Fetal growth trajectory and risk for eczema in a Saudi population.

PubMed

AlMakoshi, Amel; Ellahi, Awaiss; Sallout, Bala; Devereux, Graham; Turner, Steve

2015-12-01

Recent studies in Western cohorts have identified associations between increasing fetal abdominal circumference (AC) during mid-pregnancy and increased risk for eczema and atopy. We sought to replicate these findings in a Saudi population where antenatal environmental exposures are different compared with Western countries. A Saudi birth cohort was recruited to relate maternal dietary intake and fetal growth to wheeze, eczema, and rhinitis in the first 2 yrs. Fetal size was determined from routine ultrasound scan measurements in the second and third trimesters and birthweight was noted. Parent-reported outcomes during the first 2 yrs were acquired by telephone-administered questionnaire. There were 1076 mothers recruited. AC was determined in 562 for the second, in 632 for the third, and in 281 for both second and third trimesters. A history of eczema was determined in 814 children at 2 yrs of age. There was an inverse relationship between change in abdominal circumference between the second and third trimesters for eczema (OR 0.66 per z score increase in AC [95% CI 0.49, 0.89]), and the quartile with the greatest faltering growth were at increased risk compared with other groups (p ≤ 0.045). Change in fetal size between the third trimester and birth was not associated with altered eczema risk. There were no associations between fetal growth and wheeze at the age of 2 yrs. Our findings contrast observations made in Western populations but nonetheless suggest that factors associated with changing fetal growth trajectory in the second half of pregnancy are also relevant to atopy development on the global setting. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

[Effect of the development phase and growth rate of a Shigella sonnei population on the reproduction of homologous bacteriophage].

PubMed

Voroshilova, N N; Kazakova, T B

1983-04-01

This study showed that the minimum latent period (20 minutes) of the intracellular multiplication of dysentery bacteriophage S-9 in the population of S. sonnei substrate strain under the conditions of static heterogeneous surface batch cultivation was observed at the end of the lag phase and at the growth acceleration phase, in the first and second thirds of the exponential curve, while the maximum latent period (35-40 minutes) was observed at the stationary phase. The maximum yield of phage S-9 from one infected bacterial cell (628.3 +/- 116.8) was registered during the first third of the phase of the exponential growth of the bacterial population and the minimum yield (18.66 +/- 6.6), at the beginning of the lag phase. The significant direct correlation between the specific growth rate of the bacterial population and the yield of the phage from one infected bacterial cell at the end of the lag phase, at the growth acceleration and deceleration phases, as well as the significant inverse correlation between the yield of the phage and the time of the generation of the bacterial population at the growth acceleration phase were established.

Impacts of population growth and economic development on water quality of a lake: case study of Lake Victoria Kenya water.

PubMed

Juma, Dauglas Wafula; Wang, Hongtao; Li, Fengting

2014-04-01

Anthropogenic-induced water quality pollution is a major environmental problem in freshwater ecosystems today. As a result of this, eutrophication of lakes occurs. Population and economic development are key drivers of water resource pollution. To evaluate how growth in the riparian population and in the gross domestic product (GDP) with unplanned development affects the water quality of the lake, this paper evaluates Lake Victoria Kenyan waters basin. Waters quality data between 1990 and 2012 were analyzed along with reviews of published literature, papers, and reports. The nitrate-nitrogen (NO3-N), soluble phosphorus (PO4-P), chlorophyll a, and Secchi transparencies were evaluated as they are key water quality indicators. The NO3-N increased from 10 μg l(-1) in 1990 to 98 μg 1(-1) in 2008, while PO4-P increased from 4 μg l(-1) in 1990 to 57 μg l(-1) in 2008. The population and economic growth of Kenya are increasing with both having minimums in 1990 of 24.143 million people and 12.18 billion US dollars, to maximums in 2010 of 39.742 million people and 32.163 billion US dollars, respectively. A Secchi transparency is reducing with time, indicating an increasing pollution. This was confirmed by an increase in aquatic vegetation using an analysis of moderate resolution imaging spectroradiometer (MODIS) images of 2000 and 2012 of Kenyan waters. This study found that increasing population and GDP increases pollution discharge thus polluting lakes. One of major factors causing lake water pollution is the unplanned or poor waste management policy and service.

Integrating physiological and biomechanical drivers of population growth over environmental gradients on coral reefs.

PubMed

Madin, Joshua S; Hoogenboom, Mia O; Connolly, Sean R

2012-03-15

Coral reefs exhibit marked spatial and temporal variability, and coral reef organisms exhibit trade-offs in functional traits that influence demographic performance under different combinations of abiotic environmental conditions. In many systems, trait trade-offs are modelled using an energy and/or nutrient allocation framework. However, on coral reefs, differences in biomechanical vulnerability have major demographic implications, and indeed are believed to play an essential role in mediating species coexistence because highly competitive growth forms are vulnerable to physical dislodgment events that occur with high frequency (e.g. annual summer storms). Therefore, an integrated energy allocation and biomechanics framework is required to understand the effect of physical environmental gradients on species' demographic performance. However, on coral reefs, as in most ecosystems, the effects of environmental conditions on organisms are measured in different currencies (e.g. lipid accumulation, survival and number of gametes), and thus the relative contributions of these effects to overall capacity for population growth are not readily apparent. A comprehensive assessment of links between the environment and the organism, including those mediated by biomechanical processes, must convert environmental effects on individual-level performance (e.g. survival, growth and reproduction) into a common currency that is relevant to the capacity to contribute to population growth. We outline such an approach by considering the population-level performance of scleractinian reef corals over a hydrodynamic gradient, with a focus on the integrating the biomechanical determinants of size-dependent coral colony dislodgment as a function of flow, with the effects of flow on photosynthetic energy acquisition and respiration.

NOVEL POLYPHENOLS THAT INHIBIT COLON CANCER CELL GROWTH AFFECTING CANCER CELL METABOLISM.

PubMed

Gomez de Cedron, Marta; Vargas, Teodoro; Madrona, Andres; Jimenez, Aranza; Perez Perez, Maria Jesus; Quintela, Jose Carlos; Reglero, Guillermo; San-Felix, Ana Rosa; Ramirez de Molina, Ana

2018-06-05

New series of polyphenols with a hydrophilic galloyl based "head" and a hydrophobic N-acyl "tail", linked through a serinol moiety, have been synthesized and tested against colon cancer cell growth. Our structure activity relationship studies revealed that galloyl moieties are essential for growth inhibition. Moreover, the length of the N-acyl chain is crucial for the activity. Introduction of a (Z) double bond in the acyl chain increased the anti-cancer properties. Our findings demonstrate that 16, the most potent compound within this series, has inhibitory effects on colon cancer cell growth and metabolism (glycolysis and mitochondrial respiration) at the same time that activates AMPK and induces apoptotic cell death. Based on these results we propose that 16 might reprogram colon cancer cell metabolism through AMPK activation. This might lead to alterations on cancer cell bioenergy compromising cancer cell viability. Importantly, these anti-proliferative and pro-apoptotic effects are selective for cancer cells. Accordingly, these results indicate that 16, with an unsaturated C18 chain, might be a useful prototype for the development of novel colon cancer cell growth inhibitors affecting cell metabolism. The American Society for Pharmacology and Experimental Therapeutics.

Population Growth and Economic Development: Lessons from Selected Asian Countries. Policy Development Studies, Number 10.

ERIC Educational Resources Information Center

Mason, Andrew; And Others

The major findings of a research project on the relationship between population growth and economic development are summarized in this monograph. The study compares recent demographic and economic trends in Japan, Korea, Thailand, and Indonesia to worldwide experience as described by an econometric model of population and development. The study…

Pleiotropic Genes Affecting Carcass Traits in Bos indicus (Nellore) Cattle Are Modulators of Growth

PubMed Central

Milanesi, Marco; Torrecilha, Rafaela B. P.; Carmo, Adriana S.; Neves, Haroldo H. R.; Carvalheiro, Roberto; Ajmone-Marsan, Paolo; Sonstegard, Tad S.; Sölkner, Johann; Contreras-Castillo, Carmen J.; Garcia, José F.

2016-01-01

Two complementary methods, namely Multi-Trait Meta-Analysis and Versatile Gene-Based Test for Genome-wide Association Studies (VEGAS), were used to identify putative pleiotropic genes affecting carcass traits in Bos indicus (Nellore) cattle. The genotypic data comprised over 777,000 single-nucleotide polymorphism markers scored in 995 bulls, and the phenotypic data included deregressed breeding values (dEBV) for weight measurements at birth, weaning and yearling, as well visual scores taken at weaning and yearling for carcass finishing precocity, conformation and muscling. Both analyses pointed to the pleomorphic adenoma gene 1 (PLAG1) as a major pleiotropic gene. VEGAS analysis revealed 224 additional candidates. From these, 57 participated, together with PLAG1, in a network involved in the modulation of the function and expression of IGF1 (insulin like growth factor 1), IGF2 (insulin like growth factor 2), GH1 (growth hormone 1), IGF1R (insulin like growth factor 1 receptor) and GHR (growth hormone receptor), suggesting that those pleiotropic genes operate as satellite regulators of the growth pathway. PMID:27410030

[The Marxist outlook on population].

PubMed

Qin, R

1984-09-29

Marxist population theory and world population are discussed. From his study of capitalist population theory Marx concluded, "In capitalist reproduction, poverty produces population," thus rejecting Malthusian population determinism theory and developing economic determinism. According to UN statistics, world population has stabilized since the middle of this century after having doubled every hundred years for the last 300; population in the developed countries showed a positive decrease and average net population growth of the developing countries also decreased. The premise of this paper is that population grows according to social economy development. During the last several hundred years, world wealth increased much faster than population; in the last 200 years alone, the population has increased fivefold, but wealth fortyfold. In addition, world population analysis reveals an inverse relationship between wealth and population in the developed and developing countries: the poorer the country, the greater the population. From this perspective, the study of population must begin with surplus labor. Accumulation of surplus production is the foundation of continuous social development and the basis for population growth. The major difference in methods between capitalist countries and China is that the capitalist-planned fertility affects the individual family while Chinese-planned fertility has the whole nation in mind. Human fertility is determined by the economic system. Private ownership determines the private nature of fertility and public ownership determines the public nature of fertility. Thus population development is determined by the accumulation of social wealth.

Size of clearcut opening affects species composition, growth rate, and stand characteristics.

Treesearch

Martin E. Dale; H. Clay Smith; Jeffrey N. Pearcy

1995-01-01

In the late 1950's and early 1960's, a series of studies was installed in the central hardwood forest to determine if size of clearcut opening affects the growth rate and species composition of new stands. In 1991, about 30 years after cutting, stand data were collected in 89 openings ranging in size from 0.04 to 1.61 acres. The number of stems per acre...

[The impact of population growth on Tamba Kosi, a Himalayan valley in Nepal].

PubMed

Verliat, S

1994-01-01

Two several-month-long stays in the isolated Tamba Kosi valley in Nepal in 1983 and 1986 allowed an assessment of the importance of changes in rural societies. In about 50 years, the oldest inhabitants of some villages have seen the number of houses quadruple. In the absence of reliable statistical data, the inhabitants say that the Tamba Kosi valley population has doubled in the last 25 years. This population growth exacerbates the multiethnic fight for good land (i.e., ground of modest slope, hot, and humid). Many people have emigrated, which has somewhat eased problems relative to population growth. Soil degradation, which is becoming more and more acute, drives the inhabitants to cut down trees and clear the land for cultivation of new plots. These new plots are running up against steep slopes and high altitude. Most families have barely two hectares, which must suffice to feed 5-6 people on average. This fuels intensification of agricultural production, resulting in low efficacy. Livestock mutilate forests with their hooves and teeth. The marked increase in the variety of livestock accelerates this destruction. Three types of building materials are used in this high valley: thatch, shingles (fir tree), and bamboo matting. The disappearance of wild grasses used to make thatch roofs and people moving to higher and higher altitudes resulted in use of shingles to make roofs. Buildings made of shingles, which demanded changes in construction techniques, changed the conception of homes. They became the preferred building type, which increased the demand for fir trees and deforestation. This lead to a demand for roofing material made of bamboo matting and another change in construction techniques. The retreat of the forest and disappearance of the most wanted plant species are the most spectacular impacts of population growth. This environmental degradation exacerbates erosion at all bioclimatic altitudes.

Lichen secondary metabolites affect growth of Physcomitrella patens by allelopathy.

PubMed

Goga, Michal; Antreich, Sebastian J; Bačkor, Martin; Weckwerth, Wolfram; Lang, Ingeborg

2017-05-01

Lichen secondary metabolites can function as allelochemicals and affect the development and growth of neighboring bryophytes, fungi, vascular plants, microorganisms, and even other lichens. Lichen overgrowth on bryophytes is frequently observed in nature even though mosses grow faster than lichens, but there is still little information on the interactions between lichens and bryophytes.In the present study, we used extracts from six lichen thalli containing secondary metabolites like usnic acid, protocetraric acid, atranorin, lecanoric acid, nortistic acid, and thamnolic acid. To observe the influence of these metabolites on bryophytes, the moss Physcomitrella patens was cultivated for 5 weeks under laboratory conditions and treated with lichen extracts. Toxicity of natural mixtures of secondary metabolites was tested at three selected doses (0.001, 0.01, and 0.1 %). When the mixture contained substantial amounts of usnic acid, we observed growth inhibition of protonemata and reduced development of gametophores. Significant differences in cell lengths and widths were also noticed. Furthermore, usnic acid had a strong effect on cell division in protonemata suggesting a strong impact on the early stages of bryophyte development by allelochemicals contained in the lichen secondary metabolites.Biological activities of lichen secondary metabolites were confirmed in several studies such as antiviral, antibacterial, antitumor, antiherbivore, antioxidant, antipyretic, and analgetic action or photoprotection. This work aimed to expand the knowledge on allelopathic effects on bryophyte growth.

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

PubMed

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

Population growth and development of the psocid Liposcelis brunnea (Psocoptera: Liposcelididae) at constant temperatures and relative humidities.

PubMed

Opit, G P; Throne, J E

2009-06-01

We studied the effects of temperature and relative humidity on population growth and development of the psocid Liposcelis brunnea Motschulsky. L. brunnea did not survive at 43% RH, but populations increased from 22.5 to 32.5 degrees C and 55-75% RH. Interestingly, we found population growth was higher at 63% RH than at 75% RH, and the greatest population growth was recorded at 32.5 degrees C and 63% RH. At 35 degrees C, L. brunnea nymphal survivorship was 33%, and populations declined or barely grew. L. brunnea males have two to four nymphal instars, and the percentages of males with two, three, and four instars were 13, 82, and 5%, respectively. Female L. brunnea have three to five instars, and the percentages of females with three, four, and five instars were 18, 78, and 4%, respectively. The life cycle was shorter for males than females. We developed temperature-dependent development equations for male and female eggs, individual nymphal, combined nymphal, and combined immature stages and nymphal survivorship. The ability of L. brunnea to multiply rather rapidly at 55% RH may allow it to thrive under conditions of low relative humidity where other Liposcelis species may not. These data give us a better understanding of L. brunnea population dynamics and can be used to help develop effective management strategies for this psocid.

Theory of a microfluidic serial dilution bioreactor for growth of planktonic and biofilm populations.

PubMed

Hsu, Sze-Bi; Yang, Ya-Tang

2016-04-01

We present the theory of a microfluidic bioreactor with a two-compartment growth chamber and periodic serial dilution. In the model, coexisting planktonic and biofilm populations exchange by adsorption and detachment. The criteria for coexistence and global extinction are determined by stability analysis of the global extinction state. Stability analysis yields the operating diagram in terms of the dilution and removal ratios, constrained by the plumbing action of the bioreactor. The special case of equal uptake function and logistic growth is analytically solved and explicit growth curves are plotted. The presented theory is applicable to generic microfluidic bioreactors with discrete growth chambers and periodic dilution at discrete time points. Therefore, the theory is expected to assist the design of microfluidic devices for investigating microbial competition and microbial biofilm growth under serial dilution conditions.

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

USGS Publications Warehouse

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

2015-07-14

Increasing or decreasing the total carrying capacity of all stream segments resulted in changes in equilibrium population size that were directly proportional to the change in capacity. However, changes in carrying capacity to some stream segments but not others could result in disproportionate changes in equilibrium population sizes by altering density-dependent movement and survival in the stream network. These simulations show how our IBM can provide a useful management tool for understanding the effect of restoration actions or reintroductions on carrying capacity, and, in turn, how these changes affect Moapa dace abundance. Such tools are critical for devising management strategies to achieve recovery goals.

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