WorldWideScience

Sample records for satellite population growth

  1. Population growth and economic growth.

    Science.gov (United States)

    Narayana, D L

    1984-01-01

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

  2. Modeling Exponential Population Growth

    Science.gov (United States)

    McCormick, Bonnie

    2009-01-01

    The concept of population growth patterns is a key component of understanding evolution by natural selection and population dynamics in ecosystems. The National Science Education Standards (NSES) include standards related to population growth in sections on biological evolution, interdependence of organisms, and science in personal and social…

  3. Modeling Exponential Population Growth

    Science.gov (United States)

    McCormick, Bonnie

    2009-01-01

    The concept of population growth patterns is a key component of understanding evolution by natural selection and population dynamics in ecosystems. The National Science Education Standards (NSES) include standards related to population growth in sections on biological evolution, interdependence of organisms, and science in personal and social…

  4. Frequency Population Growth Rate

    Directory of Open Access Journals (Sweden)

    Nouralah Salehi Asfiji

    2012-10-01

    Full Text Available The Solow growth model assumes that labor force grows exponentially. That is not a realistic assumption. In generalized logistic equations that describes more accurately population growth. Economic growth is not a smooth process. Real GDP has fluctuations in the growth rate. We call these fluctuations business cycles. Business cycle theory came about from the failures of classical economics in being able to illuminate on the causes of the Great Depression. The logistic growth model to explain changes in population growth rates are not. In this paper a new analysis of the population growth rate in the frequency space is described with mathematical logic and economic reasoning, so that, firstly, to a higher level of capital per capita, or at least equal to the Solow growth model reaches Second, the limits of saturation (Carrying-Capacity is not, and ultimately, population growth rates have an impact on long-term per capita amounts. The initial classic assumption is changed in this article based on the available frequencies in the population growth equation.

  5. Global population growth.

    Science.gov (United States)

    Langmore, J

    1992-07-01

    The global population passed 5 billion in 1987. In the year 2000 the world's population will be more than 6 billion, increasing by 90-100 million each year. About 95% of future demographic growth will take place in developing countries. The number of school age children is projected to increase from 940 million in 1980 to 1280 million by the year 2000. Under current labor force growth projections in developing countries, around 1.6 billion new jobs will have to be created between 1980 and 2025, with nearly 1 billion of them in Asia. Population often increases at a more rapid rate than agricultural growth. Food production per capita has declined in 70 developing countries. Much of the projected population increase will take place in environmentally fragile regions of the developing world. Population pressures contribute to deforestation, desertification, and scarcity of clean water. The United Nations Population Fund has estimated that in Asia over 43% of women not using family planning would like to postpone, space, or limit their childbearing. Over half of the world's couples of reproductive age are now using contraception. Family planning to postpone the first birth and to eliminate late child bearing would reduce both child loss and maternal illness and death. Both infant and maternal mortality are greater with higher order births. Reducing average family size is an effective way of reducing infant and maternal mortality. The World Bank has given high priority to population assistance, with large programs in Bangladesh, Egypt, India, Indonesia, the Philippines, and Thailand. Population assistance provided by the Australian International Development Assistance Bureau totaled about $4.5 million during 1989-90 and is expected to be about $8 million during 1991-92. Australia should increase the proportion of its development assistance budget devoted to population, and family planning programs should increase to around $26 million in line with other major donors.

  6. The reionization of galactic satellite populations

    Energy Technology Data Exchange (ETDEWEB)

    Ocvirk, P.; Gillet, N.; Aubert, D.; Chardin, J. [Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS UMR 7550, 11 rue de l' Université, F-67000 Strasbourg (France); Knebe, A.; Yepes, G. [Grupo de Astrofísica, Departamento de Fisica Teorica, Modulo C-8, Universidad Autónoma de Madrid, Cantoblanco E-280049 (Spain); Libeskind, N.; Gottlöber, S. [Leibniz-Institute für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Hoffman, Y. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)

    2014-10-10

    We use high-resolution simulations of the formation of the local group, post-processed by a radiative transfer code for UV photons, to investigate the reionization of the satellite populations of an isolated Milky Way-M31 galaxy pair in a variety of scenarios. We use an improved version of ATON which includes a simple recipe for radiative feedback. In our baseline models, reionization is initiated by low-mass, radiatively regulated halos at high redshift, until more massive halos appear, which then dominate and complete the reionization process. We investigate the relation between reionization history and present-day positions of the satellite population. We find that the average reionization redshift (z {sub r}) of satellites is higher near galaxy centers (MW and M31). This is due to the inside out reionization patterns imprinted by massive halos within the progenitor during the epoch of reionization, which end up forming the center of the galaxy. Due to incomplete dynamical mixing during galaxy assembly, these early patterns survive to present day, resulting in a clear radial gradient in the average satellite reionization redshift, up to the virial radius of MW and M31 and beyond. In the lowest emissivity scenario, the outer satellites are reionized about 180 Myr later than the inner satellites. This delay decreases with increasing source model emissivity, or in the case of external reionization by Virgo or M31, because reionization occurs faster overall and becomes spatially quasi-uniform at the highest emissivity.

  7. Population growth and economic growth: any connection?

    Science.gov (United States)

    Kasun, J R

    1982-12-01

    The author examines the current evidence concerning the relationship between population growth and economic growth, with particular reference to the justification for U.S. assistance to programs designed to slow rates of population growth in developing countries. It is concluded that "the results of economic theory and research do not support the oft-repeated claims that population growth inhibits economic growth." The author suggests that the reason for continued U.S. support for population programs is the effectiveness of a population lobby that has a vested interest in the continuation of such assistance.

  8. The reionization of galactic satellite populations

    CERN Document Server

    Ocvirk, P; Aubert, D; Knebe, A; Libeskind, N; Chardin, J; Gottlöber, S; Yepes, G; Hoffman, Y

    2014-01-01

    We use high resolution simulations of the formation of the local group post-processed by a radiative transfer code for UV photons, to investigate the reionization of the satellite populations of an isolated Milky Way-M31 galaxy pair in a variety of scenarios. We use an improved version of ATON which includes a simple recipe for radiative feedback. In our baseline models, reionization is initiated by low mass, radiatively regulated haloes at high redshift, until more massive haloes appear, which then dominate and complete the reionization process. We investigate the relation between reionization history and present-day positions of the satellite population. We find that the average reionization redshift (zr) of satellites is higher near galaxy centers (MW and M31). This is due to the inside-out reionization patterns imprinted by massive haloes within the progenitor during the EoR, which end up forming the center of the galaxy. Thanks to incomplete dynamical mixing during galaxy assembly, these early patterns s...

  9. Population growth, poverty and health.

    Science.gov (United States)

    Kibirige, J S

    1997-07-01

    One of the most popular explanations for the many problems that face Africa is population growth. Africa's population has doubled since 1960. Africa has the highest fertility rate in the world and the rate of population growth is higher than in any other region. At the same time, Africa faces a social and economic situation that is viewed by many as alarming. Among the problems that devastate Africa is that of persistent poor health. Africa has lower life expectancy, higher mortality rates and is affected by more disease and illness conditions than any other region. Focusing on sub-Saharan Africa, this paper examines the relationship between population growth, poverty and poor health. While most analyses have focused on population growth as an original cause of poverty and underdevelopment, this paper argues that while both population growth and poor health play a significant role in exacerbating the problem of poverty, they are themselves primary consequences of poverty rather than its cause.

  10. BMP signaling regulates satellite cell-dependent postnatal muscle growth.

    Science.gov (United States)

    Stantzou, Amalia; Schirwis, Elija; Swist, Sandra; Alonso-Martin, Sonia; Polydorou, Ioanna; Zarrouki, Faouzi; Mouisel, Etienne; Beley, Cyriaque; Julien, Anaïs; Le Grand, Fabien; Garcia, Luis; Colnot, Céline; Birchmeier, Carmen; Braun, Thomas; Schuelke, Markus; Relaix, Frédéric; Amthor, Helge

    2017-08-01

    Postnatal growth of skeletal muscle largely depends on the expansion and differentiation of resident stem cells, the so-called satellite cells. Here, we demonstrate that postnatal satellite cells express components of the bone morphogenetic protein (BMP) signaling machinery. Overexpression of noggin in postnatal mice (to antagonize BMP ligands), satellite cell-specific knockout of Alk3 (the gene encoding the BMP transmembrane receptor) or overexpression of inhibitory SMAD6 decreased satellite cell proliferation and accretion during myofiber growth, and ultimately retarded muscle growth. Moreover, reduced BMP signaling diminished the adult satellite cell pool. Abrogation of BMP signaling in satellite cell-derived primary myoblasts strongly diminished cell proliferation and upregulated the expression of cell cycle inhibitors p21 and p57 In conclusion, these results show that BMP signaling defines postnatal muscle development by regulating satellite cell-dependent myofiber growth and the generation of the adult muscle stem cell pool. © 2017. Published by The Company of Biologists Ltd.

  11. Human Population: Fundamentals of Growth and Change.

    Science.gov (United States)

    Stauffer, Cheryl Lynn, Ed.

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

  12. City Population Growth and Economic Growth

    DEFF Research Database (Denmark)

    Freire-Gibb, L. Carlos

    2008-01-01

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

  13. Canada's population: growth and dualism.

    Science.gov (United States)

    Beaujot, R P

    1978-04-01

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

  14. Food production and population growth.

    Science.gov (United States)

    Pereira, H C

    1993-07-01

    Governments have frequently ignored the issue of population consumption exceeding the rates of renewal of natural resources. At the UN Conference on the Environment and Development in Rio de Janeiro, the issue of population growth was ignored in the agenda and action plan. In 1974, the UN World Population Conference suggested population stability would be possible if standards of living were raised. Industrialized nations spent half a century of active interference with the stability of global populations and failed to slow growth. 27 countries, mainly in tropical and subtropical zones, have an average cereal yield of under 1 ton per hectare, when improved seed and basic minimum fertilizer could yield 2 tons per hectare. Efforts to increase yields by the Consultative Group for International Agricultural research in 13 international centers resulted in global annual increases of about 50 million tons of grain (wheat and rice). Rainfed agriculture did not benefit as much because of climatic conditions. Where varieties of triticale, sorghum, millet, groundnuts, chick peas, cowpeas, beans, and cassava have helped increase food production, population growth has outstripped the gains. Agricultural fertilizers have been unfairly blamed for soil nutrient losses. Because of the age structure of population, the expected population growth can only be addressed through development of higher yields, new strains resistant to disease, and fertilizers. Slow release phosphates for tropical soils are needed. Shortages of domestic fuel divert much needed farmyard manure and composted crop residues. About 400 million tons of dung are thus wasted annually; food grain harvests are thus reduced by 14 million tons. About 50% of the 1133 million poorest people will live in Asia and another 25% will live in Sub-Saharan Africa, living on a total degraded area of 1219 million hectares. Imbalance between food supply and population need to be addressed on an effective international scale.

  15. Population growth and its implications

    Directory of Open Access Journals (Sweden)

    Badii, M. H.

    2005-01-01

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

  16. Population Growth: Family Planning Programs.

    Science.gov (United States)

    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…

  17. Political economy of population growth.

    Science.gov (United States)

    Mehta, S; Mehta, H S

    1987-01-01

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

  18. Reliability Growth Analysis of Satellite Systems

    Science.gov (United States)

    2012-09-01

    obtained. In addition, the Cumulative Intensity Function ( CIF ) of a family of satellite systems was analyzed to assess its similarity to that of a...parameters are obtained. In addition, the Cumulative Intensity Function ( CIF ) of a family of satellite systems was analyzed to assess its similarity to that...System Figures 7a through 7i display the real CIF for a variety of GOES missions. These cumulative intensity functions have shapes similar to the

  19. Population, growth and health expenditure

    Directory of Open Access Journals (Sweden)

    Luis Currais

    2000-12-01

    Full Text Available A genuine understanding of the economic growth process should take into account the extent to which fertility and mortality affect the population growth rate as an endogenous variable. To this end we construct a growth model using an infinite horizon setup in which economic development and health status influence the population growth rate. Mortality depends on health expenditure, and fertility is endogenously determined. Adults within each household take into account the welfare and resources of their current and future descendants. Their decisions determine not only the evolution of the population growth rate but also the evolution of the per capita income.Este artigo analisa a mortalidade e a fertilidade como variáveis endógenas ao modelo e determinantes do crescimento da população associado ao processo de crescimento econômico. Com este propósito, é desenvolvido um modelo de horizonte infinito onde tanto o nível de desenvolvimento econômico quanto o gasto em saúde influenciam a taxa de crescimento da população. Cada família toma suas decisões tendo em conta o bem-estar social e os recursos disponíveis de seus descendentes atuais e futuros. Suas decisões determinam não só a evolução da taxa de crescimento da população, mas também a evolução da renda per capita.

  20. Population growth and global warming

    Science.gov (United States)

    Short, R.V.

    2009-01-01

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

  1. Satellite Data Inform Forecasts of Crop Growth

    Science.gov (United States)

    2015-01-01

    During a Stennis Space Center-led program called Ag 20/20, an engineering contractor developed models for using NASA satellite data to predict crop yield. The model was eventually sold to Genscape Inc., based in Louisville, Kentucky, which has commercialized it as LandViewer. Sold under a subscription model, LandViewer software provides predictions of corn production to ethanol plants and grain traders.

  2. Reduced satellite cell population may lead to contractures in children with cerebral palsy.

    Science.gov (United States)

    Smith, Lucas R; Chambers, Henry G; Lieber, Richard L

    2013-03-01

    Satellite cells are the stem cells residing in muscle responsible for skeletal muscle growth and repair. Skeletal muscle in cerebral palsy (CP) has impaired longitudinal growth that results in muscle contractures. We hypothesized that the satellite cell population would be reduced in contractured muscle. We compared the satellite cell populations in hamstring muscles from participants with CP contracture (n=8; six males, two females; age range 6-15y; Gross Motor Function Classification System [GMFCS] levels II-V; 4 with hemiplegia, 4 with diplegia) and from typically developing participants (n=8; six males, two females, age range 15-18y). Muscle biopsies were extracted from the gracilis and semitendinosus muscles and mononuclear cells were isolated. Cell surface markers were stained with fluorescently conjugated antibodies to label satellite cells (neural cell adhesion molecule) and inflammatory and endothelial cells (CD34 and CD4 respectively). Cells were analyzed using flow cytometry to determine cell populations. After gating for intact cells a mean of 12.8% (SD 2.8%) were determined to be satellite cells in typically developing children, but only 5.3% (SD 2.3%; p0.05) suggesting the isolation procedure was valid. A reduced satellite cell population may account for the decreased longitudinal growth of muscles in CP that develop into fixed contractures or the decreased ability to strengthen muscle in CP. This suggests a unique musculoskeletal disease mechanism and provides a potential therapeutic target for debilitating muscle contractures. © The Authors. Developmental Medicine & Child Neurology © 2012 Mac Keith Press.

  3. The satellite cell in male and female, developing and adult mouse muscle: distinct stem cells for growth and regeneration.

    Directory of Open Access Journals (Sweden)

    Alice Neal

    Full Text Available Satellite cells are myogenic cells found between the basal lamina and the sarcolemma of the muscle fibre. Satellite cells are the source of new myofibres; as such, satellite cell transplantation holds promise as a treatment for muscular dystrophies. We have investigated age and sex differences between mouse satellite cells in vitro and assessed the importance of these factors as mediators of donor cell engraftment in an in vivo model of satellite cell transplantation. We found that satellite cell numbers are increased in growing compared to adult and in male compared to female adult mice. We saw no difference in the expression of the myogenic regulatory factors between male and female mice, but distinct profiles were observed according to developmental stage. We show that, in contrast to adult mice, the majority of satellite cells from two week old mice are proliferating to facilitate myofibre growth; however a small proportion of these cells are quiescent and not contributing to this growth programme. Despite observed changes in satellite cell populations, there is no difference in engraftment efficiency either between satellite cells derived from adult or pre-weaned donor mice, male or female donor cells, or between male and female host muscle environments. We suggest there exist two distinct satellite cell populations: one for muscle growth and maintenance and one for muscle regeneration.

  4. The Optimum Growth Rate for Population Reconsidered

    OpenAIRE

    Jaeger, Klaus; Kuhle, Wolfgang

    2007-01-01

    This article gives exact general conditions for the existence of an interior optimum growth rate for population in the neoclassical two-generations-overlapping model. In an economy where high (low) growth rates of population lead to a growth path which is efficient (inefficient) there always exists an interior optimum growth rate for population. In all other cases there exists no interior optimum. The Serendipity Theorem, however, does in general not hold in an economy with government debt. M...

  5. The population factor in economic growth theory

    NARCIS (Netherlands)

    Meilink, H.A.

    1974-01-01

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

  6. Population and Economic Growth in Developing Countries

    Directory of Open Access Journals (Sweden)

    Minh Quang Dao

    2012-01-01

    Full Text Available This paper examines the economic effects of the demographic transition in developing countries. Based on data from the World Bank and using a sample of forty-three developing economies, we find that the growth rate of per capita GDP is linearly dependent upon population growth, both the young and old dependency ratios, the mortality rate, and whether or not the rate of population growth is less than 1.2 percent per year. Using interaction variables in light of the severe degree of multicollinearity among explanatory variables, we find that per capita GDP growth linearly depends on population growth, the old dependency ratio, the mortality rate, and the interactions between population growth and both the young and old dependency ratios, between population growth and whether or not the rate of population growth is less than 1.2 percent per year, and the interaction term between the young dependency ratio and whether or not the rate of population growth is less than 1.2 percent per year. Statistical results of such an empirical examination will assist governments in devising policies aimed at influencing the economic effects of the demographic transition. Data for all variables are from the 2010 World Development Indicators. We apply the least-squares estimation technique in a multivariate linear regression. We also test for the nonlinear effect of population growth on economic growth and note that the introduction of interaction terms between population growth and dependency ratios as well as those between whether or not the population growth rate is less than 1.2 percent and population growth and the young dependency ratio yields better statistical results.

  7. Population distribution and population growth in Yogyakarta special region

    Directory of Open Access Journals (Sweden)

    Ida Bagus Mantra

    2013-07-01

    The annual rate of population growth in Yogyakarta Special Region is much lower compared with other provinces in Java. During 1961 and 1971 the rate of population growth was 1.1 percent, for the period 1971— 1980 became 1.09 percent. This region experienced a net loss of population through migration, and that the losses were greater in the poor areas of Gunung Kidul and Kulon Progo

  8. Hispanic Population Growth and Rural Income Inequality

    Science.gov (United States)

    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…

  9. Population aging and endogenous economic growth.

    Science.gov (United States)

    Prettner, Klaus

    2013-04-01

    We investigate the consequences of population aging for long-run economic growth perspectives. Our framework incorporates endogenous growth models and semi-endogenous growth models as special cases. We show that (1) increases in longevity have a positive impact on per capita output growth, (2) decreases in fertility have a negative impact on per capita output growth, (3) the positive longevity effect dominates the negative fertility effect in case of the endogenous growth framework, and (4) population aging fosters long-run growth in the endogenous growth framework, while its effect depends on the relative change between fertility and mortality in the semi-endogenous growth framework.Electronic supplementary material The online version of this article (doi:10.1007/s00148-012-0441-9) contains supplementary material, which is available to authorized users.

  10. Segue 2: A Prototype of the Population of Satellites of Satellites

    CERN Document Server

    Belokurov, V; Evans, N W; Gilmore, G; Irwin, M J; Mateo, M; Mayer, L; Olszewski, E; Bechtold, J; Pickering, T

    2009-01-01

    We announce the discovery of a new Milky Way satellite Segue 2 found in the data of the Sloan Extension for Galactic Understanding and Exploration (SEGUE). We followed this up with deeper imaging and spectroscopy on the Multiple Mirror Telescope. From this, we derive a luminosity of M_v = -2.5, a half-light radius of 34 pc and a systemic velocity of -40$ km/s. Our MMT data also provides evidence for a stream around Segue 2 at a similar heliocentric velocity, and the SEGUE data show that it is also present in neighboring fields. We resolve the velocity dispersion of Segue 2 as 3.4 km/s and the possible stream as about 7 km/s. This object shows points of comparison with other recent discoveries, Segue 1, Boo II and Coma. We speculate that all four objects may be representatives of a population of satellites of satellites -- survivors of accretion events that destroyed their larger but less dense parents. They are likely to have formed at redshifts z > 10 and are good candidates for fossils of the reionization e...

  11. Templated growth of gold satellites on dimpled silica cores.

    Science.gov (United States)

    Chomette, C; Duguet, E; Mornet, S; Yammine, E; Manoharan, V N; Schade, N B; Hubert, C; Ravaine, S; Perro, A; Tréguer-Delapierre, M

    2016-10-06

    We synthesize robust clusters of gold satellites positioned with tetrahedral symmetry on the surface of a patchy silica core by adsorption and growth of gold on the patches. First we conduct emulsion polymerization of styrene in the presence of 52 nm silica seeds whose surface has been modified with methacryloxymethyltriethoxysilane (MMS). We derive four-dimple particles from the resulting silica/polystyrene tetrapods. Polystyrene chains are covalently bound to the silica surface within the dimples due to the MMS grafts and they may be thiolated to induce adsorption of 12 nm gold particles. Using chloroauric acid, ascorbic acid and sodium citrate at room temperature, we grow gold from these 12 nm seeds without detachment from or deformation of the dimpled silica surface. We obtain gold satellites of tunable diameter up to 140 nm.

  12. Stochastic population growth in spatially heterogeneous environments.

    Science.gov (United States)

    Evans, Steven N; Ralph, Peter L; Schreiber, Sebastian J; Sen, Arnab

    2013-02-01

    Classical ecological theory predicts that environmental stochasticity increases extinction risk by reducing the average per-capita growth rate of populations. For sedentary populations in a spatially homogeneous yet temporally variable environment, a simple model of population growth is a stochastic differential equation dZ(t) = μZ(t)dt + σZ(t)dW(t), t ≥ 0, where the conditional law of Z(t+Δt)-Z(t) given Z(t) = z has mean and variance approximately z μΔt and z²σ²Δt when the time increment Δt is small. The long-term stochastic growth rate lim(t→∞) t⁻¹ log Z(t) for such a population equals μ − σ²/2 . Most populations, however, experience spatial as well as temporal variability. To understand the interactive effects of environmental stochasticity, spatial heterogeneity, and dispersal on population growth, we study an analogous model X(t) = (X¹(t) , . . . , X(n)(t)), t ≥ 0, for the population abundances in n patches: the conditional law of X(t+Δt) given X(t) = x is such that the conditional mean of X(i)(t+Δt) − X(i)(t) is approximately [x(i)μ(i) + Σ(j) (x(j) D(ji) − x(i) D(i j) )]Δt where μ(i) is the per capita growth rate in the ith patch and D(ij) is the dispersal rate from the ith patch to the jth patch, and the conditional covariance of X(i)(t+Δt)− X(i)(t) and X(j)(t+Δt) − X(j)(t) is approximately x(i)x(j)σ(ij)Δt for some covariance matrix Σ = (σ(ij)). We show for such a spatially extended population that if S(t) = X¹(t)+· · ·+ X(n)(t) denotes the total population abundance, then Y(t) = X(t)/S(t), the vector of patch proportions, converges in law to a random vector Y(∞) as t → ∞, and the stochastic growth rate lim(t→∞) t⁻¹ log S(t) equals the space-time average per-capita growth rate Σ(i)μ(i)E[Y(i)(∞)] experienced by the population minus half of the space-time average temporal variation E[Σ(i,j) σ(i j)Y(i)(∞) Y(j)(∞)] experienced by the population. Using this characterization of the

  13. Population priorities: the challenge of continued rapid population growth.

    Science.gov (United States)

    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.

  14. Solar furnace satellite for large diameter crystal growth in space

    Science.gov (United States)

    Overfelt, Tony; Wells, Mark; Blake, John

    1993-02-01

    Investigators worldwide are preparing experiments to test the influence of low gravity found in space on the growth of many crystalline materials. However, power limitations prevent existing space crystal growth furnaces from being able to process samples any larger than about 2 cm, and in addition, the background microgravity levels found on the Space Shuttle are not low enough to significantly benefit samples much larger than 2 cm. This paper describes a novel concept of a free-flying platform utilizing well-established solar furnace technology to enable materials processing in space experiments on large-diameter crystals. The conceptual design of this Solar Furnace Satellite is described along with its operational scenario and the anticipated g levels.

  15. Asynchronous exponential growth of a bacterial population

    Directory of Open Access Journals (Sweden)

    Mohamed Boulanouar

    2014-01-01

    Full Text Available In this work, we complete a study started earlier in [1,2] wherein a model of growing bacterial population has been the matter of a mathematical analysis. We show that the full model is governed by a strongly continuous semigroup. Beside the positivity and the irreducibility of the generated semigroup, we describe its asymptotic behavior in the uniform topology which leads to the asynchronous exponential growth of the bacterial population.

  16. Keynes on population and economic growth.

    Science.gov (United States)

    Toye, J

    1997-01-01

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

  17. Population-based geographic access to parent and satellite National Cancer Institute Cancer Center Facilities.

    Science.gov (United States)

    Onega, Tracy; Alford-Teaster, Jennifer; Wang, Fahui

    2017-09-01

    Satellite facilities of National Cancer Institute (NCI) cancer centers have expanded their regional footprints. This study characterized geographic access to parent and satellite NCI cancer center facilities nationally overall and by sociodemographics. Parent and satellite NCI cancer center facilities, which were geocoded in ArcGIS, were ascertained. Travel times from every census tract in the continental United States and Hawaii to the nearest parent and satellite facilities were calculated. Census-based population attributes were used to characterize measures of geographic access for sociodemographic groups. From the 62 NCI cancer centers providing clinical care in 2014, 76 unique parent locations and 211 satellite locations were mapped. The overall proportion of the population within 60 minutes of a facility was 22% for parent facilities and 32.7% for satellite facilities. When satellites were included for potential access, the proportion of some racial groups for which a satellite was the closest NCI cancer center facility increased notably (Native Americans, 22.6% with parent facilities and 39.7% with satellite facilities; whites, 34.8% with parent facilities and 50.3% with satellite facilities; and Asians, 40.0% with parent facilities and 54.0% with satellite facilities), with less marked increases for Hispanic and black populations. Rural populations of all categories had dramatically low proportions living within 60 minutes of an NCI cancer center facility of any type (1.0%-6.6%). Approximately 14% of the population (n = 43,033,310) lived more than 180 minutes from a parent or satellite facility, and most of these individuals were Native Americans and/or rural residents (37% of Native Americans and 41.7% of isolated rural residents). Racial/ethnic and rural populations showed markedly improved geographic access to NCI cancer center care when satellite facilities were included. Cancer 2017;123:3305-11. © 2017 American Cancer Society. © 2017 American

  18. Molecular and functional heterogeneity of early postnatal porcine satellite cell populations is associated with bioenergetic profile

    Science.gov (United States)

    Miersch, Claudia; Stange, Katja; Hering, Silvio; Kolisek, Martin; Viergutz, Torsten; Röntgen, Monika

    2017-01-01

    During postnatal development, hyperplastic and hypertrophic processes of skeletal muscle growth depend on the activation, proliferation, differentiation, and fusion of satellite cells (SC). Therefore, molecular and functional SC heterogeneity is an important component of muscle plasticity and will greatly affect long-term growth performance and muscle health. However, its regulation by cell intrinsic and extrinsic factors is far from clear. In particular, there is only minor information on the early postnatal period which is critical for muscle maturation and the establishment of adult SC pools. Here, we separated two SC subpopulations (P40/50, P50/70) from muscle of 4-day-old piglets. Our results characterize P40/50 as homogeneous population of committed (high expression of Myf5), fast-proliferating muscle progenitors. P50/70 constituted a slow-proliferating phenotype and contains high numbers of differentiated SC progeny. During culture, P50/70 is transformed to a population with lower differentiation potential that contains 40% Pax7-positive cells. A reversible state of low mitochondrial activity that results from active down-regulation of ATP-synthase is associated with the transition of some of the P50/70 cells to this more primitive fate typical for a reserve cell population. We assume that P40/50 and P50/70 subpopulations contribute unequally in the processes of myofiber growth and maintenance of the SC pool. PMID:28344332

  19. Impact of demographic policy on population growth.

    Science.gov (United States)

    Podyashchikh, P

    1968-01-01

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

  20. Economic Development and Population Growth. International Evidence Economic Development and Population Growth. International Evidence

    Directory of Open Access Journals (Sweden)

    Munir Quddus

    1986-03-01

    Full Text Available Economic Development and Population Growth. International Evidence The paper usses Granger causality tests on economic development and population growth for 44 countries to discriminate among several alternative hypotheses. The time series evidence does not provide an unambiguous picture as to the exact nature of the relationship. Therefore, previous attempts to generalize such relationship based on simple cross-section data are strongly suspect.

  1. The SAGA Survey. I. Satellite Galaxy Populations around Eight Milky Way Analogs

    Science.gov (United States)

    Geha, Marla; Wechsler, Risa H.; Mao, Yao-Yuan; Tollerud, Erik J.; Weiner, Benjamin; Bernstein, Rebecca; Hoyle, Ben; Marchi, Sebastian; Marshall, Phil J.; Muñoz, Ricardo; Lu, Yu

    2017-09-01

    We present the survey strategy and early results of the “Satellites Around Galactic Analogs” (SAGA) Survey. The SAGA Survey’s goal is to measure the distribution of satellite galaxies around 100 systems analogous to the Milky Way down to the luminosity of the Leo I dwarf galaxy ({M}rgri color criteria. We have discovered a total of 25 new satellite galaxies: 14 new satellite galaxies meet our formal criteria around our complete host systems, plus 11 additional satellites in either incompletely surveyed hosts or below our formal magnitude limit. Combined with 13 previously known satellites, there are a total of 27 satellites around 8 complete Milky-Way-analog hosts. We find a wide distribution in the number of satellites per host, from 1 to 9, in the luminosity range for which there are 5 Milky Way satellites. Standard abundance matching extrapolated from higher luminosities predicts less scatter between hosts and a steeper luminosity function slope than observed. We find that the majority of satellites (26 of 27) are star-forming. These early results indicate that the Milky Way has a different satellite population than typical in our sample, potentially changing the physical interpretation of measurements based only on the Milky Way’s satellite galaxies.

  2. Effects of the Global Population Growth

    Directory of Open Access Journals (Sweden)

    Voiculeţ Alina

    2017-01-01

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

  3. [Models of economic theory of population growth].

    Science.gov (United States)

    Von Zameck, W

    1987-01-01

    "The economic theory of population growth applies the opportunity cost approach to the fertility decision. Variations and differentials in fertility are caused by the available resources and relative prices or by the relative production costs of child services. Pure changes in real income raise the demand for children or the total amount spent on children. If relative prices or production costs and real income are affected together the effect on fertility requires separate consideration." (SUMMARY IN ENG)

  4. Satellite DNA as a driver of population divergence in the red flour beetle Tribolium castaneum.

    Science.gov (United States)

    Feliciello, Isidoro; Akrap, Ivana; Brajković, Josip; Zlatar, Ivo; Ugarković, Đurđica

    2014-12-19

    Tandemly repeated satellite DNAs are among most rapidly evolving sequences in eukaryotic genome, usually differing significantly among closely related species. By inducing changes in heterochromatin and/or centromere, satellite DNAs are expected to drive population and species divergence. However, despite high evolutionary dynamics, divergence of satellite DNA profiles at the level of natural population which precedes and possibly triggers speciation process is not readily detected. Here, we characterize minor TCAST2 satellite DNA of the red flour beetle Tribolium castaneum and follow its dynamics among wild-type strains originating from diverse geographic locations. The investigation revealed presence of three distinct subfamilies of TCAST2 satellite DNA which differ in monomer size, genome organization, and subfamily specific mutations. Subfamilies Tcast2a and Tcast2b are tandemly arranged within pericentromeric heterochromatin whereas Tcast2c is preferentially dispersed within euchromatin of all chromosomes. Among strains, TCAST2 subfamilies are conserved in sequence but exhibit a significant content variability. This results in overrepresentation or almost complete absence of particular subfamily in some strains and enables discrimination between strains. It is proposed that homologous recombination, probably stimulated by environmental stress, is responsible for the emergence of TCAST2 satellite subfamilies, their copy number variation and dispersion within genome. The results represent the first evidence for the existence of population-specific satellite DNA profiles. Partial organization of TCAST2 satellite DNA in the form of single repeats dispersed within euchromatin additionally contributes to the genome divergence at the population level.

  5. Satellite data for Singapore, Manila and Kuala Lumpur city growth analysis

    Directory of Open Access Journals (Sweden)

    Mukesh Singh Boori

    2016-06-01

    Full Text Available This data article presents satellite data related to city growth of Singapore, Manila and Kuala Lumpur cities. The data were collected from NASA and USGS websites. A method has been developed for city built-up density from city center to outward till 50 km by using satellite data. These data sets consists three decade Landsat images. A detailed description is given to show how to use this data to produce urban growth maps. The urban growth maps have been used to know the changes and growth pattern in the Southeast Asia Cities.

  6. Satellite data for Singapore, Manila and Kuala Lumpur city growth analysis.

    Science.gov (United States)

    Boori, Mukesh Singh; Choudhary, Komal; Kupriyanov, Alexander; Kovelskiy, Viktor

    2016-06-01

    This data article presents satellite data related to city growth of Singapore, Manila and Kuala Lumpur cities. The data were collected from NASA and USGS websites. A method has been developed for city built-up density from city center to outward till 50 km by using satellite data. These data sets consists three decade Landsat images. A detailed description is given to show how to use this data to produce urban growth maps. The urban growth maps have been used to know the changes and growth pattern in the Southeast Asia Cities.

  7. Population Growth, (Per Capita) Economic Growth, and Poverty Reduction in Uganda: Theory and Evidence

    OpenAIRE

    Stephan Klasen

    2005-01-01

    This paper examines the link between population and per capita economic growth in Uganda. After showing that Uganda has one of the highest population growth rates in the world which, due to the inherent demographic momentum, will persist for some time to come, it then considers the impact of population growth on per capita economic growth. It finds that both theoretical considerations as well as strong empirical evidence suggest that the currently high population growth puts a considerable br...

  8. Circadian rhythm and cell population growth

    CERN Document Server

    Clairambault, Jean; Lepoutre, Thomas

    2010-01-01

    Molecular circadian clocks, that are found in all nucleated cells of mammals, are known to dictate rhythms of approximately 24 hours (circa diem) to many physiological processes. This includes metabolism (e.g., temperature, hormonal blood levels) and cell proliferation. It has been observed in tumor-bearing laboratory rodents that a severe disruption of these physiological rhythms results in accelerated tumor growth. The question of accurately representing the control exerted by circadian clocks on healthy and tumour tissue proliferation to explain this phenomenon has given rise to mathematical developments, which we review. The main goal of these previous works was to examine the influence of a periodic control on the cell division cycle in physiologically structured cell populations, comparing the effects of periodic control with no control, and of different periodic controls between them. We state here a general convexity result that may give a theoretical justification to the concept of cancer chronothera...

  9. Beijing moves to curb population growth.

    Science.gov (United States)

    Pao, T K

    Education and incentives are being used to encourage a "one-child for one-family" campaign in Beijing. The goal is to reduce its population growth rate to 5%/1000 by 1985. Parents who have only child will receive a certificate entitling the only child to preferential treatment for nursery or kindergarten and medical care. 1-child families will receive an annual bonus of 60 yuan. Those who have more than 2 children will be taxed a minimum of 10% of salaries. Single, childless people will receive their full salaries as pensions on retirement. All urban families will receive the same housing space no matter what size the family. The same will be true for the size of small plots of land parcelled out for private use in the rural suburban area. Sterilization operations are available for those who wish them. Parents with 1 child who have such operations can have their tubes rejoined free of charge if their child is disabled or dies. The average growth rate for China projected for 1978-1000 is 1.2%.

  10. How will Population Aging Affect Economic Growth?

    Institute of Scientific and Technical Information of China (English)

    蔡昉; 王美艳

    2007-01-01

    Not long ago,the problem of an aging population only emerged in developed countries once per capita GDP had reached a relatively high level.However,in today’s China,although the per capita GDP has remained low,the problem of growing old before becoming rich is looming.As China is not yet prosperous,economic development needs to be persistently upheld;however,will the aging problem cause economic growth to be challenged by labour shortages in the future? From a structural perspective,although continuous rural labour transfer can ease demand for urban labour,the problem now is that rural labourers are not always qualified to take on positions requiring ever-advancing skills,resulting in a skills drought.It could be claimed that this skills drought is due to a lack of education on the part of rural workers,yet university students with a formal education also encounter difficulties when hunting for a job.Does this indicate that the current education structure should be revised? The above questions suggest that China is currently facing a complicated and delicate situation with regard to the interrelated problems of economy,population,employment and education,and will continue to do so for a long period in the future.These problems require the cautious planning of overall and sustainable policies.The two"Domestic Column"articles this issue offer in-depth analyses of these problems and provide valuable policy suggestions.

  11. Function of Membrane-Associated Proteoglycans in the Regulation of Satellite Cell Growth.

    Science.gov (United States)

    Song, Yan

    2016-01-01

    Muscle growth can be divided into embryonic and postnatal periods. During the embryonic period, mesenchymal stem cells proliferate and differentiate to form muscle fibers. Postnatal muscle growth (hypertrophy) is characterized by the enlargement of existing muscle fiber size. Satellite cells (also known as adult myoblasts) are responsible for hypertrophy. The activity of satellite cells can be regulated by their extracellular matrix (ECM). The ECM is composed of collagens, proteoglycans, non-collagenous glycoproteins, cytokines and growth factors. Proteoglycans contain a central core protein with covalently attached glycosaminoglycans (GAGs: chondroitin sulfate, keratan sulfate, dermatan sulfate, and heparan sulfate) and N- or O-linked glycosylation chains. Membrane-associated proteoglycans attach to the cell membrane either through a glycosylphosphatidylinositol anchor or transmembrane domain. The GAGs can bind proteins including cytokines and growth factors. Both cytokines and growth factors play important roles in regulating satellite cell growth and development. Cytokines are generally associated with immune cells. However, cytokines can also affect muscle cell development. For instance, interleukin-6, tumor necrosis factor-α, and leukemia inhibitory factor have been reported to affect the proliferation and differentiation of satellite cells and myoblasts. Growth factors are potent stimulators or inhibitors of satellite cell proliferation and differentiation. The proper function of some cytokines and growth factors requires an interaction with the cell membrane-associated proteoglycans to enhance the affinity to bind to their primary receptors to initiate downstream signal transduction. This chapter is focused on the interaction of membrane-associated proteoglycans with cytokines and growth factors, and their role in satellite cell growth and development.

  12. Population growth and human capital: a welfarist approach

    OpenAIRE

    Thomas Renstrom; Luca Spataro

    2014-01-01

    In this paper we investigate the relationship between economic and population growth in an endogenous growth model driven by human capital accumulation à la Lucas (1988). Since we allow for endogenous population growth, we adopt the population criterion Relative Critical Level Utilitarianism (an extension of Critical Level Utilitarianism, Blackorby et al. 1995) which allows axiomatically founded welfare orderings under variable population. Under this extension the Critical Level Utility is de...

  13. The Massive Satellite Population of Milky-Way Sized Galaxies

    CERN Document Server

    Rodriguez-Puebla, A; Drory, N

    2013-01-01

    Occupational distributions for satellite galaxies ms>4E7Msun around Milky-Way-sized(MW-s) hosts are presented and used to predict the internal dynamics of these sats. For the analysis, a galaxy group mock catalog is constructed on the basis of (sub)halo-to-stellar mass relations fully constrained with available observations; the stellar mass function of centrals and satellites, and the 2-point correlation function. 6.6% of MW-s galaxies host 2 sats in the mass range of the Small and Large Magellanic Clouds (SMC and LMC). The probabilities of the MW-s galaxies to have 1 sat>= the LMC or 2 sats>= the SMC or 3 sats>= Saggitarius (Sgr) are ~0.26,0.14, and 0.14. MW-s hosting 3 sats>= Sgr (as the MW) are among the most common cases. However, the most and 2nd most massive sats in these systems are ms) for MW-s galaxies is broad, the case of the MW being of low frequency but not an outlier. The Mh of MW-s galaxies correlates only weakly with N(>ms). Then, it is not possible to accurately determine the MW halo mass by...

  14. Satellite-aided evaluation of population exposure to air pollution

    Science.gov (United States)

    Todd, W. J.; George, A. J., Jr.; Bryant, N. A.

    1979-01-01

    The evaluation of population exposure to air pollution through the computer processing of Landsat digital land use data, along with total suspended particulate estimates and population data by census tracts, is demonstrated. Digital image processing was employed to analyze simultaneously data from Landsat MSS bands 4 through 7 in order to extract land use and land cover information. The three data sets were spatially registered in a digital format, compatible with integrated computer processing, and cross-tabulated. A map illustrating relative air quality by 2-sq km cells for the residential population in the Portland, Oregon area is obtained.

  15. Satellite Image Edge Detection for Population Distribution Pattern Identification using Levelset with Morphological Filtering Process

    Science.gov (United States)

    Harsiti; Munandar, T. A.; Suhendar, A.; Abdullah, A. G.; Rohendi, D.

    2017-03-01

    Population distribution pattern is directly related with economic gap of a region. Analysis of population distribution pattern is usually performed by studying statistical data on population. This study aimed to analyze population distribution pattern using image analysis concept, i.e. using satellite images. Levelset and morphological image filtering methods were used to analyze images to see distribution pattern. The research result showed that Levelset and morphological image filtering could remove a lot of noises in analysis result images and form object edge contours very clearly. The detected object contours were used as references to recognize population distribution pattern based on satellite image analysis. The pattern made based on the research result didn’t show optimal result because Levelset performed image segmentation based on the contours of the analyzed objects. Other segmentation methods should be combined with it to produce clearer population distribution pattern.

  16. Population Growth and Poverty in the Developing World.

    Science.gov (United States)

    Birdsall, Nancy

    1980-01-01

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

  17. An observer's guide to the (Local Group) dwarf galaxies: predictions for their own dwarf satellite populations

    CERN Document Server

    Dooley, Gregory A; Yang, Tianyi; Willman, Beth; Griffen, Brendan F; Frebel, Anna

    2016-01-01

    A recent surge in the discovery of new ultrafaint dwarf satellites of the Milky Way has inspired the idea of searching for faint satellites, $10^3\\, \\mathrm{M_{\\odot}}99\\%$ chance that at least one satellite with stellar mass $M_*> 10^5 \\, \\mathrm{M_{\\odot}}$ exists around the combined five Local Group field dwarf galaxies with the largest stellar mass. When considering satellites with $M_*> 10^4 \\, \\mathrm{M_{\\odot}}$, we predict a combined $5-25$ satellites for the five largest field dwarfs, and $10-50$ for the whole Local Group field dwarf population. Because of the relatively small number of predicted dwarfs, and their extended spatial distribution, a large fraction each Local Group dwarf's virial volume will need to be surveyed to guarantee discoveries. We compute the predicted number of satellites in a given field of view of specific Local Group galaxies, as a function of minimum satellite luminosity, and explicitly obtain such values for the Solitary Local dwarfs survey. Uncertainties in abundance matc...

  18. Salamander limb regeneration involves the activation of a multipotent skeletal muscle satellite cell population.

    Science.gov (United States)

    Morrison, Jamie I; Lööf, Sara; He, Pingping; Simon, András

    2006-01-30

    In contrast to mammals, salamanders can regenerate complex structures after injury, including entire limbs. A central question is whether the generation of progenitor cells during limb regeneration and mammalian tissue repair occur via separate or overlapping mechanisms. Limb regeneration depends on the formation of a blastema, from which the new appendage develops. Dedifferentiation of stump tissues, such as skeletal muscle, precedes blastema formation, but it was not known whether dedifferentiation involves stem cell activation. We describe a multipotent Pax7+ satellite cell population located within the skeletal muscle of the salamander limb. We demonstrate that skeletal muscle dedifferentiation involves satellite cell activation and that these cells can contribute to new limb tissues. Activation of salamander satellite cells occurs in an analogous manner to how the mammalian myofiber mobilizes stem cells during skeletal muscle tissue repair. Thus, limb regeneration and mammalian tissue repair share common cellular and molecular programs. Our findings also identify satellite cells as potential targets in promoting mammalian blastema formation.

  19. The entwined growth of population and product, 1922-1982.

    Science.gov (United States)

    Ben-porath, Y

    1997-01-01

    This article "discusses aggregate-level interactions between Jewish immigration and economic growth both in the Jewish sector of Mandatory Palestine and in Israel". The reciprocal effects of population and economic growth are discussed in two sections on population as an engine of growth and was the size of the population dependent on the economy. The author concludes that "causality between population and [gross national] product runs both ways.... For the whole period 1922-1982, it is very clear that immigration pushed the rate of increase of capital stock. For the period from 1954 on, immigration responded to the growth rate of per capita income or consumption." excerpt

  20. A quantitative explanation of the observed population of Milky Way satellite galaxies

    CERN Document Server

    Koposov, Sergey E; Rix, Hans-Walter; Weinberg, David H; Macciò, Andrea V; Miralda-Escudé, Jordi

    2009-01-01

    We revisit the well known discrepancy between the observed number of Milky Way (MW) dwarf satellite companions and the predicted population of cold dark matter (CDM) sub-halos, in light of the dozen new low luminosity satellites found in SDSS imaging data and our recent calibration of the SDSS satellite detection efficiency, which implies a total population far larger than these dozen discoveries. We combine a dynamical model for the CDM sub-halo population with simple, physically motivated prescriptions for assigning stellar content to each sub-halo, then apply observational selection effects and compare to the current observational census. As expected, models in which the stellar mass is a constant fraction F(Omega_b/Omega_m) of the sub-halo mass M_sat at the time it becomes a satellite fail for any choice of F. However, previously advocated models that invoke suppression of gas accretion after reionization in halos with circular velocity v_c <~ 35 km/s can reproduce the observed satellite counts for -15...

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

    OpenAIRE

    Rosenzweig, Mark R.

    1987-01-01

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

  2. Muscle Interstitial Cells: A Brief Field Guide to Non-satellite Cell Populations in Skeletal Muscle.

    Science.gov (United States)

    Tedesco, Francesco Saverio; Moyle, Louise A; Perdiguero, Eusebio

    2017-01-01

    Skeletal muscle regeneration is mainly enabled by a population of adult stem cells known as satellite cells. Satellite cells have been shown to be indispensable for adult skeletal muscle repair and regeneration. In the last two decades, other stem/progenitor cell populations resident in the skeletal muscle interstitium have been identified as "collaborators" of satellite cells during regeneration. They also appear to have a key role in replacing skeletal muscle with adipose, fibrous, or bone tissue in pathological conditions. Here, we review the role and known functions of these different interstitial skeletal muscle cell types and discuss their role in skeletal muscle tissue homeostasis, regeneration, and disease, including their therapeutic potential for cell transplantation protocols.

  3. The effect of population growth in China in the course of economic growth.

    Science.gov (United States)

    Zhang, S

    1993-01-01

    The interaction of population and economic growth in China was analyzed between 1953 and 1989. The principle index for population-economic growth was differential per capita income, or income exceeding the basic minimum standard of living. Population growth occurred when per capita income was higher than the standard up to a threshold level, after which population declined. Rapid population growth decreased differential per capital income. Differential per capita income was considered the better measure of the interaction between economic conditions and population growth. Time-series differential per capita income measures were provided annually. Differential income per capita was accounted for by differential per capita investment, marginal productiveness of differential per capital investment, and labor force input on differential per capita income. Measures accounted for a constant tariff and labor productivity. The results showed the depletion effect on national income from increased population growth. Prior to 1978, the economic depletion in China was due to the impact of the marginal population and, after 1978, the depletion was due to increased consumption. Income increased from 2.53 yuan in 1953 to 8.64 in 1989; the average annual growth of the per capita consumption level increased from 2.1% between 1966 and 1973 to 8.7% by 1989. The depletion intensity of population growth on differential per capita income varied with population growth rates; it tended to fall over time, but differential per capita income would not be reduced to zero or a "low level income trough." The blockage of economic growth from population growth was evidenced in 13 specific years. The average coefficient between 1953 and 1989 was 0.58, which indicated that the blockage effect from population growth was less than the impetus effect of economic growth, but still high enough to offset rapid economic growth. Graphing the interaction between differential income growth and population

  4. Using high-resolution satellite imagery to assess populations of animals in the Antarctic

    Science.gov (United States)

    LaRue, Michelle Ann

    The Southern Ocean is one of the most rapidly-changing ecosystems on the planet due to the effects of climate change and commercial fishing for ecologically-important krill and fish. It is imperative that populations of indicator species, such as penguins and seals, be monitored at regional- to global scales to decouple the effects of climate and anthropogenic changes for appropriate ecosystem-based management of the Southern Ocean. Remotely monitoring populations through high-resolution satellite imagery is currently the only feasible way to gain information about population trends of penguins and seals in Antarctica. In my first chapter, I review the literature where high-resolution satellite imagery has been used to assess populations of animals in polar regions. Building on this literature, my second chapter focuses on estimating changes in abundance in the Weddell seal population in Erebus Bay. I found a strong correlation between ground and satellite counts, and this finding provides an alternate method for assessing populations of Weddell seals in areas where less is known about population status. My third chapter explores how size of the guano stain of Adelie penguins can be used to predict population size. Using high-resolution imagery and ground counts, I built a model to estimate the breeding population of Adelie penguins using a supervised classification to estimate guano size. These results suggest that the size of guano stain is an accurate predictor of population size, and can be applied to estimate remote Adelie penguin colonies. In my fourth chapter, I use air photos, satellite imagery, climate and mark-resight data to determine that climate change has positively impacted the population of Adelie penguins at Beaufort Island through a habitat release that ultimately affected the dynamics within the southern Ross Sea metapopulation. Finally, for my fifth chapter I combined the literature with observations from aerial surveys and satellite imagery to

  5. Confidence interval for number of population in dynamical stochastic exponential population growth models

    Directory of Open Access Journals (Sweden)

    Morteza Khodabin

    2013-06-01

    Full Text Available In this paper, the confidence interval for the solution of stochastic exponential population growth model where the so-called parameter, population growth rate is not completely definite and it depends on some random environmental effects is obtained. We use Iran population data in the period 1921-2006 as an example.

  6. Muscle Atrophy Reversed by Growth Factor Activation of Satellite Cells in a Mouse Muscle Atrophy Model

    DEFF Research Database (Denmark)

    Hauerslev, Simon; Vissing, John; Krag, Thomas O

    2014-01-01

    Muscular dystrophies comprise a large group of inherited disorders that lead to progressive muscle wasting. We wanted to investigate if targeting satellite cells can enhance muscle regeneration and thus increase muscle mass. We treated mice with hepatocyte growth factor and leukemia inhibitory...... factor under three conditions: normoxia, hypoxia and during myostatin deficiency. We found that hepatocyte growth factor treatment led to activation of the Akt/mTOR/p70S6K protein synthesis pathway, up-regulation of the myognic transcription factors MyoD and myogenin, and subsequently the negative growth...... control factor, myostatin and atrophy markers MAFbx and MuRF1. Hypoxia-induced atrophy was partially restored by hepatocyte growth factor combined with leukemia inhibitory factor treatment. Dividing satellite cells were three-fold increased in the treatment group compared to control. Finally, we...

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

    Directory of Open Access Journals (Sweden)

    Gunter Zeug

    2010-04-01

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

  8. Muscle atrophy reversed by growth factor activation of satellite cells in a mouse muscle atrophy model.

    Directory of Open Access Journals (Sweden)

    Simon Hauerslev

    Full Text Available Muscular dystrophies comprise a large group of inherited disorders that lead to progressive muscle wasting. We wanted to investigate if targeting satellite cells can enhance muscle regeneration and thus increase muscle mass. We treated mice with hepatocyte growth factor and leukemia inhibitory factor under three conditions: normoxia, hypoxia and during myostatin deficiency. We found that hepatocyte growth factor treatment led to activation of the Akt/mTOR/p70S6K protein synthesis pathway, up-regulation of the myognic transcription factors MyoD and myogenin, and subsequently the negative growth control factor, myostatin and atrophy markers MAFbx and MuRF1. Hypoxia-induced atrophy was partially restored by hepatocyte growth factor combined with leukemia inhibitory factor treatment. Dividing satellite cells were three-fold increased in the treatment group compared to control. Finally, we demonstrated that myostatin regulates satellite cell activation and myogenesis in vivo following treatment, consistent with previous findings in vitro. Our results suggest, not only a novel in vivo pharmacological treatment directed specifically at activating the satellite cells, but also a myostatin dependent mechanism that may contribute to the progressive muscle wasting seen in severely affected patients with muscular dystrophy and significant on-going regeneration. This treatment could potentially be applied to many conditions that feature muscle wasting to increase muscle bulk and strength.

  9. Green sea turtle age, growth, population characteristics

    Data.gov (United States)

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

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

    NARCIS (Netherlands)

    Hartemink, A.E.

    2007-01-01

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

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

    Science.gov (United States)

    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.

  12. The population growth and desertification crisis.

    Science.gov (United States)

    Milas, S

    1985-01-01

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

  13. The demographic imperative: managing population growth

    NARCIS (Netherlands)

    A.M. Fischer (Andrew Martín)

    2010-01-01

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

  14. Bounded Population Growth: A Curve Fitting Lesson.

    Science.gov (United States)

    Mathews, John H.

    1992-01-01

    Presents two mathematical methods for fitting the logistic curve to population data supplied by the U.S. Census Bureau utilizing computer algebra software to carry out the computations and plot graphs. (JKK)

  15. Demographic heterogeneity, cohort selection, and population growth

    OpenAIRE

    Bruce E. Kendall; Fox, Gordon A.; Fujiwara, Masami; Nogeire, Theresa M.

    2011-01-01

    Demographic heterogeneity—variation among individuals in survival and reproduction—is ubiquitous in natural populations. Structured population models address heterogeneity due to age, size, or major developmental stages. However, other important sources of demographic heterogeneity, such as genetic variation, spatial heterogeneity in the environment, maternal effects, and differential exposure to stressors, are often not easily measured and hence are modeled as stochasticity. Recent research ...

  16. Temperature effect on proliferation and differentiation of satellite cells from turkeys with different growth rates.

    Science.gov (United States)

    Clark, D L; Coy, C S; Strasburg, G M; Reed, K M; Velleman, S G

    2016-04-01

    Poultry selected for growth have an inefficient thermoregulatory system and are more sensitive to temperature extremes. Satellite cells are precursors to skeletal muscle and mediate all posthatch muscle growth. Their physiological functions are affected by temperature. The objective of the current study was to determine how temperature affects satellite cells isolated from the pectoralis major (p. major) muscle (breast muscle) of turkeys selected for increased 16 wk body weight (F line) in comparison to a randombred control line (RBC2) from which the F line originated. Pectoralis major muscle satellite cells were thermally challenged by culturing between 33°C and 43°C to analyze the effects of cold and heat on proliferation and differentiation as compared to control temperature of 38°C. Expression levels of myogenic regulatory factors: myogenic differentiation factor 1 (MYOD1) and myogenin (MYOG) were quantified by quantitative polymerase chain reaction (qPCR). At all sampling times, proliferation increased at a linear rate across temperature in both the RBC2 and F lines. Differentiation also increased at a linear rate across temperature from 33 to 41°C at all sampling times in both the F and RBC2 lines. Satellite cells isolated from F line turkeys were more sensitive to both hot and cold temperatures as proliferation and differentiation increased to a greater extent across temperature (33 to 43°C) when compared with the RBC2 line. Expression of MYOD1 and MYOG increased as temperatures increased from 33 to 41°C at all sampling times in both the F and RBC2 lines. These results demonstrate that satellite cell function is sensitive to both cold and hot temperatures and p. major muscle satellite cells from F line turkeys are more sensitive to temperature extremes than RBC2 satellite cells.

  17. Population growth and endogenous technological change: Australian economic growth in the long run

    OpenAIRE

    Banerjee, Rajabrata

    2011-01-01

    The Australian growth experience appears to be a three-act phenomenon, with higher per capita income and living standards before 1890 and after 1940, disconnected by a 50-year period of no trend improvement in between. This paper examines the roles of technological progress and population growth in Australian productivity growth over the past two centuries. The empirical results confirm that while population growth had a negative effect, innovative activity had a positive effect on productivi...

  18. [Five recommendations for controlling population growth in China].

    Science.gov (United States)

    Lui, Z; Wu, C P; Lin, F D

    1980-10-01

    The rapid population growth rate (2% annually from 1949 to 1978) caused great difficulties for China's national economy because it increased the burden of families, communities, and government. It caused employment problems and slowed increases in living standards and educational levels. The best way to control population growth is based on a combination of political education and effective economic measures. The recommendations are: 1) coordinate employment, food rationing, salaries, bonuses, health treatment, age and condition of retirement, preschool care and education with family planning programs, maintain the elderly's living standard, and give preference to childless and single child families; 2) educate people about family planning and incorporate population growth and family planning into political and economics courses in high school and college; 3) incorporate population control into national economic plans; 4) prohibit families with 3 children and advocate 1 child per couple; and 5) establish a permanent population committee to plan, develop, and implement population policies and related research.

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

    Science.gov (United States)

    Luallen, Jeremy; Cutler, Christopher

    2017-09-01

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

  20. Urban population and economic growth: South Asia perspective

    Directory of Open Access Journals (Sweden)

    Sandip Sarker

    2016-07-01

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

  1. Population growth in the cities of Irbid Governorate, Jordan.

    Science.gov (United States)

    Khamis, M

    1985-12-01

    This discussion of population growth in the cities of Irbid Governorate, Jordan, covers population growth development city inhabitants before the 20th century; city population in the 20th century; population growth factors; natural growth; migration patterns; and migration factors. Despite the fact that no census was conducted before the turn of this century, estimates indicate that no significant variation in the population growth of the cities was registered. Between 1946-52, Jordanian cities witnessed a significant population growth because of Palestinian immigration to Jordan, leading to a 3-fold increase in comparison with the 1946 figure. A historical review of development in Irbid cities shows a decline in population stability in the city of Ajlun after the end of the "Al-Mamalik" rule and the population was confined to a limited number of families. This trend continued until the early 18th century when a number of people from nearby areas settled in the cities. Since then and up to the end of the past century, population growth was slow due to high mortality rates. As for the cities of Ramtha and Shuna, Ramtha has maintained its population because of its geographical location, and the city of northern Shuna accommodated a number of families only. Population growth of Irbid cities in the 1st half of the 20th century was characterized by slow development and fluctuation and by sharp declines in some years, attributable to high mortality rates caused by epidemics, wars, and conflicts. In the 1930s, mortality rates in Jordan, in general, reached 25-27/1000; birth rates were estimated at 48/1000, a natural increase of 2% annually. Like other Jordanian cities, those in the Irbid governorate witnessed a noticeable population growth that was attributed to the growth in the State's population. Population growth has varied significantly among the cities of the governorate, ranging from 1 to 9% annually with no major differences in the natural growth for each city

  2. The role of ejecta in the small crater populations on the mid-sized saturnian satellites

    Science.gov (United States)

    Bierhaus, Edward B.; Dones, Luke; Alvarellos, José Luis; Zahnle, Kevin

    2012-03-01

    We find evidence, by both observation and analysis, that primary crater ejecta play an important role in the small crater (less than a few km) populations on the saturnian satellites, and more broadly, on cratered surfaces throughout the Solar System. We measure crater populations in Cassini images of Enceladus, Rhea, and Mimas, focusing on image data with scales less than 500 m/pixel. We use recent updates to crater scaling laws and their constants (Housen, K.R., Holsapple, K.A. [2011]. Icarus 211, 856-875) to estimate the amount of mass ejected in three different velocity ranges: (i) greater than escape velocity, (ii) less than escape velocity and faster than the minimum velocity required to make a secondary crater (vmin), and (iii) velocities less than vmin. Although the vast majority of mass on each satellite is ejected at speeds less than vmin, our calculations demonstrate that the differences in mass available in the other two categories should lead to observable differences in the small crater populations; the predictions are borne out by the measurements we have made to date. In particular, Rhea, Tethys, and Dione have sufficient surface gravities to retain ejecta moving fast enough to make secondary crater populations. The smaller satellites, such as Enceladus but especially Mimas, are expected to have little or no traditional secondary populations because their escape velocities are near the threshold velocity necessary to make a secondary crater. Our work clarifies why the Galilean satellites have extensive secondary crater populations relative to the saturnian satellites. The presence, extent, and sizes of sesquinary craters (craters formed by ejecta that escape into temporary orbits around Saturn before re-impacting the surface, see Dobrovolskis, A.R., Lissauer, J.J. [2004]. Icarus 169, 462-473; Alvarellos, J.L., Zahnle, K.J., Dobrovolskis, A.R., Hamill, P. [2005]. Icarus 178, 104-123; Zahnle, K., Alvarellos, J.L., Dobrovolskis, A.R., Hamill, P. [2008

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

    Science.gov (United States)

    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.

  4. Parameter Estimates in Differential Equation Models for Population Growth

    Science.gov (United States)

    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,…

  5. The old age security hypothesis and optimal population growth.

    Science.gov (United States)

    Bental, B

    1989-03-01

    The application of the Samuelson-Diamond overlapping generations framework to the old age security hypothesis indicates that government intervention schemes can influence the relationship between population growth and capital accumulation. The most direct means of optimizing population growth is through taxes or subsidies that relate to the intergenerational transfer of wealth. A pay-as-you-go social security scheme, in which payment is predicated on the number of children the receiver has and is financed by taxes levied on the working population, emerges as the most likely intervention to produce the optimal steady state equilibrium. This system is able to correct any distortions the private sector may build into it. In contrast, a child support system, in which the government subsidizes or taxes workers according to their family size, can guarantee the optimal capital:labor ratio but not the optimal population growth rate. Thus, if the government seeks to decrease the population growth rate, the appropriate intervention is to levy a lump-sum social-security tax on workers and transfer the revenues to the old; the direction should be reversed if the goal is to increase population growth. Another alternative, a lump sum social security system, can guarantee optimal population growth but not a desirable capital:labor ratio. Finally, the introduction of money as a valued commodity into an economy with a high capital:labor ratio will also serve to decrease the population growth rate and solve the intergenerational transfer problem through the private sector without any need for government intervention.

  6. Population growth and economic development revisited with reference to Asia.

    Science.gov (United States)

    Jha, S C; Deolalikar, A B; Pernia, E M

    1993-01-01

    "This article takes another look at the old issue of population growth and economic development in the context of recent developments and with the benefit of the increasing stock of knowledge on the subject. It first presents a demographic perspective; then it analyzes the implications of population growth with respect to such integral aspects of economic development as human capital accumulation, income distribution and poverty, the environment, and sustainable economic growth. The approach in each case is to review the theoretical considerations, survey the empirical evidence, and then draw policy implications. An overall conclusion with implications for policy caps the paper." The geographical focus is on Asia.

  7. Growth of a young pingo in the Canadian Arctic observed by RADARSAT-2 interferometric satellite radar

    OpenAIRE

    Samsonov, Sergey V.; Lantz, Trevor C.; Kokelj, Steven V; Zhang, Yu

    2016-01-01

    Advancements in radar technology are increasing our ability to detect Earth surface deformation in permafrost environments. In this paper we use satellite Differential Interferometric Synthetic Aperture Radar (DInSAR) to describe the growth of a large, relatively young pingo in the Tuktoyaktuk Coastlands. High-resolution RADARSAT-2 imagery (2011–2014) analyzed with the Multidimensional Small Baseline Subset (MSBAS) DInSAR revealed a maximum 2.7 cm yr−1 of domed uplift locate...

  8. Current Characteristics and Trends of the Tracked Satellite Population in the Human Space Flight Regime

    Science.gov (United States)

    Johnson, Nicholas L.

    2006-01-01

    Since the end of the Apollo program in 1972, human space flight has been restricted to altitudes below 600 km above the Earth s surface with most missions restricted to a ceiling below 400 km. An investigation of the tracked satellite population transiting and influencing the human space flight regime during the past 11 years (equivalent to a full solar cycle) has recently been completed. The overall effects of satellite breakups and solar activity are typically less pronounced in the human space flight regime than other regions of low Earth orbit. As of January 2006 nearly 1500 tracked objects resided in or traversed the human space flight regime, although two-thirds of these objects were in orbits of moderate to high eccentricity, significantly reducing their effect on human space flight safety. During the period investigated, the spatial density of tracked objects in the 350-400 km altitude regime of the International Space Station demonstrated a steady decline, actually decreasing by 50% by the end of the period. On the other hand, the region immediately above 600 km experienced a significant increase in its population density. This regime is important for future risk assessments, since this region represents the reservoir of debris which will influence human space flight safety in the future. The paper seeks to put into sharper perspective the risks posed to human space flight by the tracked satellite population, as well as the influences of solar activity and the effects of compliance with orbital debris mitigation guidelines on human space flight missions. Finally, the methods and successes of characterizing the population of smaller debris at human space flight regimes are addressed.

  9. Surface growth of a motile bacterial population resembles growth in a chemostat.

    Science.gov (United States)

    Koster, Daniel A; Mayo, Avraham; Bren, Anat; Alon, Uri

    2012-12-07

    The growth behavior in well-mixed bacterial cultures is relatively well understood. However, bacteria often grow in heterogeneous conditions on surfaces where their growth is dependent on spatial position, especially in the case of motile populations. For such populations, the relation between growth, motility and spatial position is unclear. We developed a microscope-based assay for quantifying in situ growth and gene expression in space and time, and we observe these parameters in populations of Escherichia coli swimming in galactose soft agar plates. We find that the bacterial density and the shape of the motile population, after an initial transient, are constant in time. By considering not only the advancing population but also the fraction that lags behind, we propose a growth model that relates spatial distribution, motility and growth rate. This model, that is similar to bacterial growth in a chemostat predicts that the fraction of the population lagging behind is inversely proportional to the velocity of the motile population. We test this prediction by modulating motility using inducible expression of the flagellar sigma factor FliA. Finally, we observe that bacteria in the chemotactic ring express higher relative levels of the chemotaxis and galactose metabolism genes fliC, fliL and galE than those that stay behind in the center of the plate.

  10. TOPICAL PROBLEMS: The phenomenological theory of world population growth

    Science.gov (United States)

    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.

  11. How does cell size regulation affect population growth?

    CERN Document Server

    Lin, Jie

    2016-01-01

    The proliferation of a growing microbial colony is well characterized by the population growth rate. However, at the single-cell level, isogenic cells often exhibit different cell-cycle durations. For evolutionary dynamics, it is thus important to establish the connection between the population growth rate and the heterogeneous single-cell generation time. Existing theories often make the assumption that the generation times of mother and daughter cells are independent. However, it has been shown that to maintain a bounded cell size distribution, cells that grow exponentially at the single-cell level need to adopt cell size regulation, leading to a negative correlation of mother-daughter generation time. In this work, we construct a general framework to describe the population growth in the presence of size regulation. We derive a formula for the population growth rate, which only depends on the variability of single-cell growth rate, independent of other sources of noises. Our work shows that a population ca...

  12. Population growth and the development of a central place system

    Science.gov (United States)

    Cromley, Robert G.; Hanink, Dean M.

    2008-12-01

    This paper describes the spatial and functional evolution of a central place system as market conditions change with population growth. Utilizing a partial equilibrium optimization model, we examine the spatial response of two economic sectors to increases in market populations resulting from natural increase and migration. Response in both sectors is conditioned by threshold demand, with factor prices also affecting one of the sectors. As the central place system evolves it exhibits spatial and functional characteristics that are initially consistent with a Löschian landscape, then a Christallerian landscape at higher populations, while at even larger populations Krugman’s landscape emerges.

  13. "Runaway" population growth to hurt RP's economy -- ADB.

    Science.gov (United States)

    The Asian Development Bank (ADB) has raised concern over continued growth of the Filipino population. The ADB stated that increase in population could have a negative effect on economic development and social welfare. In its annual Asian Development Outlook, the ADB reported that the Philippines¿ 2.3% annual increase in population is attributable to Filipino couples' lack of knowledge about or the means to practice effective birth control, as well as to the presence of "incentives for couples to have many children". The ADB recommended that the Philippines should establish a strong population policy based on combined economic incentives and adequate family planning services supported by a committed government.

  14. Validity and feasibility of a satellite imagery-based method for rapid estimation of displaced populations

    Directory of Open Access Journals (Sweden)

    Checchi Francesco

    2013-01-01

    Full Text Available Abstract Background Estimating the size of forcibly displaced populations is key to documenting their plight and allocating sufficient resources to their assistance, but is often not done, particularly during the acute phase of displacement, due to methodological challenges and inaccessibility. In this study, we explored the potential use of very high resolution satellite imagery to remotely estimate forcibly displaced populations. Methods Our method consisted of multiplying (i manual counts of assumed residential structures on a satellite image and (ii estimates of the mean number of people per structure (structure occupancy obtained from publicly available reports. We computed population estimates for 11 sites in Bangladesh, Chad, Democratic Republic of Congo, Ethiopia, Haiti, Kenya and Mozambique (six refugee camps, three internally displaced persons’ camps and two urban neighbourhoods with a mixture of residents and displaced ranging in population from 1,969 to 90,547, and compared these to “gold standard” reference population figures from census or other robust methods. Results Structure counts by independent analysts were reasonably consistent. Between one and 11 occupancy reports were available per site and most of these reported people per household rather than per structure. The imagery-based method had a precision relative to reference population figures of Conclusions In settings with clearly distinguishable individual structures, the remote, imagery-based method had reasonable accuracy for the purposes of rapid estimation, was simple and quick to implement, and would likely perform better in more current application. However, it may have insurmountable limitations in settings featuring connected buildings or shelters, a complex pattern of roofs and multi-level buildings. Based on these results, we discuss possible ways forward for the method’s development.

  15. Sphingosine-1-phosphate mediates epidermal growth factor-induced muscle satellite cell activation

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, Yosuke, E-mail: cynagata@mail.ecc.u-tokyo.ac.jp; Ohashi, Kazuya; Wada, Eiji; Yuasa, Yuki; Shiozuka, Masataka; Nonomura, Yoshiaki; Matsuda, Ryoichi

    2014-08-01

    Skeletal muscle can regenerate repeatedly due to the presence of resident stem cells, called satellite cells. Because satellite cells are usually quiescent, they must be activated before participating in muscle regeneration in response to stimuli such as injury, overloading, and stretch. Although satellite cell activation is a crucial step in muscle regeneration, little is known of the molecular mechanisms controlling this process. Recent work showed that the bioactive lipid sphingosine-1-phosphate (S1P) plays crucial roles in the activation, proliferation, and differentiation of muscle satellite cells. We investigated the role of growth factors in S1P-mediated satellite cell activation. We found that epidermal growth factor (EGF) in combination with insulin induced proliferation of quiescent undifferentiated mouse myoblast C2C12 cells, which are also known as reserve cells, in serum-free conditions. Sphingosine kinase activity increased when reserve cells were stimulated with EGF. Treatment of reserve cells with the D-erythro-N,N-dimethylsphingosine, Sphingosine Kinase Inhibitor, or siRNA duplexes specific for sphingosine kinase 1, suppressed EGF-induced C2C12 activation. We also present the evidence showing the S1P receptor S1P2 is involved in EGF-induced reserve cell activation. Moreover, we demonstrated a combination of insulin and EGF promoted activation of satellite cells on single myofibers in a manner dependent on SPHK and S1P2. Taken together, our observations show that EGF-induced satellite cell activation is mediated by S1P and its receptor. - Highlights: • EGF in combination with insulin induces proliferation of quiescent C2C12 cells. • Sphingosine kinase activity increases when reserve cells are stimulated with EGF. • EGF-induced activation of reserve cells is dependent on sphingosine kinase and ERK. • The S1P receptor S1P2 is involved in EGF-induced reserve cell activation. • EGF-induced reserve cell activation is mediated by S1P and its

  16. [Economic growth and changes in the structure of the population].

    Science.gov (United States)

    Conroy, M E

    1980-01-01

    A reevaluation of classic works by Simon Kuznets and Wassily Leontief suggests that their conclusions concerning the interrelationships between economic growth and population structure correspond to relatively highly specialized characteristics of present forms of capitalist development or underdevelopment and not necessarily to capitalist development within a new international economic order or to socialist development. Kuznets' work seems to offer conclusive proof of the negative effects of rapid population growth on economic development for 3 reasons: 1) requirements for capital are greater, 2) total production and per capita consumption are greatly reduced with high dependency ratios, and 3) rapid growth in consumption is more difficult when the population is growing more rapidly. However, at least 4 problems are noted when Kuznets' ideas are applied to the 3rd world. Kuznets assumes that growth of physical capital is the only source of growth, so that only increased investment can increase returns. Secondly, assuming the same ratio of capital/output for all cases assumes that no substitution of labor for capital is possible. Third, the assumption that participation rates remain the same regardless of dependency ratios may be incorrect. And finally, the difference in per capita consumption that Kuznets attributes to differences in rates of population growth represents a tiny proportion of the total gap in the standard of living of rich countries with slow population growth and poor countries with rapid growth. Kuznets' argument has considerable validity in Third World countries which relay on traditional patterns of capitalist accumulation, but the problems represent the effects of rapid population growth only under the current modes of capitalist expansion. The negative effect of high fertility on savings has probably been greatly exaggerated, and the problems of providing educational facilities and health care for ever larger numbers of persons have been

  17. Pericytes in the myovascular niche promote post-natal myofiber growth and satellite cell quiescence.

    Science.gov (United States)

    Kostallari, Enis; Baba-Amer, Yasmine; Alonso-Martin, Sonia; Ngoh, Pamela; Relaix, Frederic; Lafuste, Peggy; Gherardi, Romain K

    2015-04-01

    The satellite cells, which serve as adult muscle stem cells, are both located beneath myofiber basement membranes and closely associated with capillary endothelial cells. We observed that 90% of capillaries were associated with pericytes in adult mouse and human muscle. During post-natal growth, newly formed vessels with their neuroglial 2 proteoglycan (NG2)-positive pericytes became progressively associated with the post-natal muscle stem cells, as myofibers increased in size and satellite cells entered into quiescence. In vitro, human muscle-derived pericytes promoted myogenic cell differentiation through insulin-like growth factor 1 (IGF1) and myogenic cell quiescence through angiopoietin 1 (ANGPT1). Diphtheria toxin-induced ablation of muscle pericytes in growing mice led both to myofiber hypotrophy and to impaired establishment of stem cells quiescence. Similar effects were observed following conditional in vivo deletion of pericyte Igf1 and Angpt1 genes, respectively. Our data therefore demonstrate that, by promoting post-natal myogenesis and stem cell quiescence, pericytes play a key role in the microvascular niche of satellite cells. © 2015. Published by The Company of Biologists Ltd.

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

    Science.gov (United States)

    Jha, S; Bawa, K S

    2006-06-01

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

  19. Vintage growth and population density: an empirical investigation.

    Science.gov (United States)

    Mcmillen, D P

    1994-11-01

    "This paper tests a central prediction of vintage growth models of urban structure: that there are discontinuities in the population density function. The data set covers quarter sections in Chicago in 1980. Using such highly disaggregated data is critical because discontinuities are less likely to be found the larger is the unit of observation. Both a switching regression model and a nonparametric estimator reveal discontinuities and upward-sloping segments in the function, which supports the vintage growth model."

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

    Directory of Open Access Journals (Sweden)

    Evelyn J. Patterson

    2017-06-01

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

  1. Hepatocyte Growth Factor-mediated satellite cells niche perturbation promotes development of distinct sarcoma subtypes.

    Science.gov (United States)

    Morena, Deborah; Maestro, Nicola; Bersani, Francesca; Forni, Paolo Emanuele; Lingua, Marcello Francesco; Foglizzo, Valentina; Šćepanović, Petar; Miretti, Silvia; Morotti, Alessandro; Shern, Jack F; Khan, Javed; Ala, Ugo; Provero, Paolo; Sala, Valentina; Crepaldi, Tiziana; Gasparini, Patrizia; Casanova, Michela; Ferrari, Andrea; Sozzi, Gabriella; Chiarle, Roberto; Ponzetto, Carola; Taulli, Riccardo

    2016-03-17

    Embryonal Rhabdomyosarcoma (ERMS) and Undifferentiated Pleomorphic Sarcoma (UPS) are distinct sarcoma subtypes. Here we investigate the relevance of the satellite cell (SC) niche in sarcoma development by using Hepatocyte Growth Factor (HGF) to perturb the niche microenvironment. In a Pax7 wild type background, HGF stimulation mainly causes ERMS that originate from satellite cells following a process of multistep progression. Conversely, in a Pax7 null genotype ERMS incidence drops, while UPS becomes the most frequent subtype. Murine EfRMS display genetic heterogeneity similar to their human counterpart. Altogether, our data demonstrate that selective perturbation of the SC niche results in distinct sarcoma subtypes in a Pax7 lineage-dependent manner, and define a critical role for the Met axis in sarcoma initiation. Finally, our results provide a rationale for the use of combination therapy, tailored on specific amplifications and activated signaling pathways, to minimize resistance emerging from sarcomas heterogeneity.

  2. Growth dynamics and the evolution of cooperation in microbial populations

    OpenAIRE

    Jonas Cremer; Anna Melbinger; Erwin Frey

    2012-01-01

    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 c...

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

    Science.gov (United States)

    Wayne C. Zipperer; Steward T.A. Pickett

    2012-01-01

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

  4. Satellite remote sensing for urban growth assessment in Shaoxing City, Zhejiang Province

    Institute of Scientific and Technical Information of China (English)

    RAMADAN Elnazir; FENG Xue-zhi (冯学智); CHENG Zheng (程征)

    2004-01-01

    Urban growth represents specific response to economic, demographic and environmental conditions. Rapid urbanization and industrializations have resulted in sharp land cover changes. The present investigation was carried out from Shaoxing City to quantify satellite-derived estimates of urban growth using a three-epoch time series Landsat TM data for the years 1984, 1997 and ETM 2000. The methodology used was based on post classification comparison. The use of GIS allowed spatial analysis of the data derived from remotely sensed images. Results showed that the built-up area surrounding Shaoxing City has expanded at an annual average of 7 km2. Analysis of the classified map showed that the physical growth of urban area is upsetting the other land cover classes such as farming, water resources, etc. The study conclusion mainly emphasized the need for sustainable urban capacity.

  5. The population growth consequences of variation in individual heterozygosity.

    Directory of Open Access Journals (Sweden)

    Martina M I Di Fonzo

    Full Text Available Heterozygosity has been associated with components of fitness in numerous studies across a wide range of taxa. Because heterozygosity is associated with individual performance it is also expected to be associated with population dynamics. However, investigations into the association between heterozygosity and population dynamics have been rare because of difficulties in linking evolutionary and ecological processes. The choice of heterozygosity measure is a further issue confounding such studies as it can be biased by individual differences in the frequencies of the alleles studied, the number of alleles at each locus as well as the total number of loci typed. In this study, we first examine the differences between the principal metrics used to calculate heterozygosity using long-term data from a marked population of Soay sheep (Ovis aries. Next, by means of statistical transformation of the homozygosity weighted by loci index, we determine how heterozygosity contributes to population growth in Soay sheep by modelling individual contributions to population growth (p(t(i as a function of several covariates, including sex, weight and faecal egg count--a surrogate of parasitic nematode burden in the gut. We demonstrate that although heterozygosity is associated with some components of fitness, most notably adult male reproductive success, in general it is only weakly associated with population growth.

  6. Proximate causes of adaptive growth rates: growth efficiency variation among latitudinal populations of Rana temporaria.

    Science.gov (United States)

    Lindgren, B; Laurila, A

    2005-07-01

    In ectothermic organisms, declining season length and lower temperature towards higher latitudes often select for latitudinal variation in growth and development. However, the energetic mechanisms underlying this adaptive variation are largely unknown. We investigated growth, food intake and growth efficiency of Rana temporaria tadpoles from eight populations along a 1500 km latitudinal gradient across Sweden. To gain an insight into the mechanisms of adaptation at organ level, we also examined variation in tadpole gut length. The tadpoles were raised at two temperatures (16 and 20 degrees C) in a laboratory common garden experiment. We found increased growth rate towards higher latitudes, regardless of temperature treatment. This increase in growth was not because of a higher food intake rate, but populations from higher latitudes had higher growth efficiency, i.e. they were more efficient at converting ingested food into body mass. Low temperature reduced growth efficiency most strongly in southern populations. Relative gut length increased with latitude, and tadpoles at low temperature tended to have longer guts. However, variation in gut length was not the sole adaptive explanation for increased growth efficiency as latitude and body length still explained significant amounts of variation in growth efficiency. Hence, additional energetic adaptations are probably involved in growth efficiency variation along the latitudinal gradient.

  7. Satellite Microwave Remote Sensing for Environmental Modeling of Mosquito Population Dynamics

    Science.gov (United States)

    Chuang, Ting-Wu; Henebry, Geoffrey M.; Kimball, John S.; VanRoekel-Patton, Denise L.; Hildreth, Michael B.; Wimberly, Michael C.

    2012-01-01

    Environmental variability has important influences on mosquito life cycles and understanding the spatial and temporal patterns of mosquito populations is critical for mosquito control and vector-borne disease prevention. Meteorological data used for model-based predictions of mosquito abundance and life cycle dynamics are typically acquired from ground-based weather stations; however, data availability and completeness are often limited by sparse networks and resource availability. In contrast, environmental measurements from satellite remote sensing are more spatially continuous and can be retrieved automatically. This study compared environmental measurements from the NASA Advanced Microwave Scanning Radiometer on EOS (AMSR-E) and in situ weather station data to examine their ability to predict the abundance of two important mosquito species (Aedes vexans and Culex tarsalis) in Sioux Falls, South Dakota, USA from 2005 to 2010. The AMSR-E land parameters included daily surface water inundation fraction, surface air temperature, soil moisture, and microwave vegetation opacity. The AMSR-E derived models had better fits and higher forecasting accuracy than models based on weather station data despite the relatively coarse (25-km) spatial resolution of the satellite data. In the AMSR-E models, air temperature and surface water fraction were the best predictors of Aedes vexans, whereas air temperature and vegetation opacity were the best predictors of Cx. tarsalis abundance. The models were used to extrapolate spatial, seasonal, and interannual patterns of climatic suitability for mosquitoes across eastern South Dakota. Our findings demonstrate that environmental metrics derived from satellite passive microwave radiometry are suitable for predicting mosquito population dynamics and can potentially improve the effectiveness of mosquito-borne disease early warning systems. PMID:23049143

  8. Economic consequences of population size, structure and growth.

    Science.gov (United States)

    Lee, R

    1983-01-01

    There seems to be 4 major approaches to conceptualizing and modeling demographic influences on economic and social welfare. These approaches are combined in various ways to construct richer and more comprehensive models. The basic approaches are: demographic influences on household or family behavior; population growth and reproducible capital; population size and fixed factors; and population and advantages of scale. These 4 models emphasize the supply side effects of population. A few of the ways in which these theories have been combined are sketched. Neoclassical growth models often have been combined with age distributed populations of individuals (or households), assumed to pursue optimal life cycle consumption and saving. In some well known development models, neoclassical growth models for the modern sector are linked by labor markets and migration to fixed factor (land) models of the traditional (agricultural) sector. A whole series of macro simulation models for developed and developing countries was based on single sector neoclassical growth models with age distributed populations. Yet, typically the household level foundations of assumed age distribution effects were not worked out. Simon's (1977) simulation models are in a class by themselves, for they are the only models that attempt to incorporate all the kinds of effects discussed. The economic demography of the individual and family cycle, as it is affected by regimes of fertility, mortality, and nuptiality, taken as given, are considered. The examination touches on many of the purported consequences of aggregate population growth and age composition, since so many of these are based implicitly or explicitly on assertions about micro level behavior. Demographic influences on saving and consumption, on general labor supply and female labor supply, and on problems of youth and old age dependency frequently fall in this category. Finally, attention is focused specifically on macro economic issues in

  9. Capital accumulation, endogenous population growth, and Easterlin cycles.

    Science.gov (United States)

    Feichtinger, G; Dockner, E J

    1990-01-01

    "In this paper we attempt to explain the occurrence of population cycles in industrialised economies where the birth rate depends on the difference between the actual and the expected consumption rate. This model of an endogenously growing population brings together Easterlin's idea of an adapting aspiration level with the neoclassical optimal growth paradigm. It is shown that in this highly aggregated demo-economic system (i.e., without inclusion of the age structure of a population) swings both in the economic and demographic variables may exist. The reason behind this 'strange' optimal behaviour is identified to be an intertemporal substitution effect between current and future levels of consumption."

  10. Food-dependent individual growth and population dynamics in fishes

    NARCIS (Netherlands)

    L. Persson; A.M. de Roos

    2006-01-01

    It is long since well established that growth and development in fish individuals are heavily dependent on food intake. Yet, this dependence of individual development on food levels has only to a limited extent been taken into consideration when studying fish population and community processes. Usin

  11. Using Satellite Data for Environmental Impact Analysis in Economic Growth: the Case of Mongolia

    Science.gov (United States)

    Tungalag, A.; Tsolmon, R.; Ochirkhuyag, L.; Oyunjargal, J.

    2016-06-01

    The Mongolian economy is based on the primary and secondary economic sectors of agriculture and industry. In addition, minerals and mining become a key sector of its economy. The main mining resources are gold, copper, coal, fluorspar and steel. However, the environment and green economy is one of the big problems among most of the countries and especially for countries like Mongolia where the mining is major part of economy; it is a number one problem. The research of the work tested how environmental elements effect to current Mongolian economic growth, which is growing economy because of mining sector. The study of economic growth but the starting point for any study of economic growth is the neoclassical growth model emphasizing the role of capital accumulation. The growth is analysed either in terms of models with exogenous saving rates (the Solow-Swan model), or models where consumption and hence savings are determined by optimizing individuals. These are the so-called optimal growth or Ramsey-Cass-Koopmans. The study extends the Solow model and the Ramsey-Cass-Koopmans model, including environmental elements which are satellite data determine to degraded land and vegetation value from 1995 to 2013. In contrast, we can see the degraded land area increases from 1995 (4856 m2) to 2013 (10478 m2) and vegetation value decrease at same time. A description of the methodology of the study conducted follows together with the data collected and econometric estimations and calibration with environmental elements.

  12. Growth of consanguineous populations: effect of family and group size

    Directory of Open Access Journals (Sweden)

    Srdjan Denic

    2012-05-01

    Full Text Available Objective: Although inbreeding is detrimental to the offspring, consanguineous marriages still remain very common in many countries. To better understand this sociobiological puzzle, we compared the growth of isolated consanguineous versus non- consanguineous populations of varying sizes. Methods: In a computer, over five generations, we simulated first cousin marriages, family size, and offspring survival to find the effect on population growth. Results: In large groups, the practice of first cousin marriages decreased the population size due to an excessive number of deaths among the offspring. In small groups, however, first cousin marriages increased the population size; without first cousins, there is a relative shortage of marriageable potential spouses. Marriages to first cousins produced additional unions and a surplus of viable offspring despite excessive deaths caused by inbreeding. Consequently, small consanguineously marrying groups grew faster than small non-consanguineously marrying groups. Independently, family size directly affected the number of consanguineous marriages and inbreeding in consanguineous groups. Conclusions: In small groups, kin marriages, despite the harms of inbreeding, result in relatively faster population growth.

  13. Determinants of Population Growth in Rajasthan: An Analysis

    CERN Document Server

    Singh, V V; Sharma, Neetish; Smarandache, Florentin

    2010-01-01

    Rajasthan is the biggest State of India and is currently in the second phase of demographic transition and is moving towards the third phase of demographic transition with very slow pace. However, state's population will continue to grow for a time period. Rajasthan's performance in the social and economic sector has been poor in past. The poor performance is the outcome of poverty, illiteracy and poor development, which co-exist and reinforce each other. There are many demographic and socio-economic factors responsible for population growth. This paper attempts to identify the demographic and socio-economic variables, which are responsible for population growth in Rajasthan with the help of multivariate analysis.

  14. Can population promote income per-capita growth? A balanced perspective

    OpenAIRE

    Frederic Tournemaine

    2007-01-01

    We develop a model in which technical progress, human capital and population interact endogenously to examine the impact of population growth on economic development. We find that population growth can be positively or negatively correlated with the growth rate of income per-capita. The outcome depends on the relative contribution of population and human capital to the determination of output growth.

  15. Critical amino acids in syndecan-4 cytoplasmic domain modulation of turkey satellite cell growth and development.

    Science.gov (United States)

    Song, Yan; McFarland, Douglas C; Velleman, Sandra G

    2012-02-01

    Syndecan-4 is composed of a core protein and covalently attached glycosaminoglycan (GAG) and N-linked glycosylated (N-glycosylated) chains. The core protein is divided into extracellular, transmembrane, and cytoplasmic domains. The cytoplasmic domain has two conserved regions and a variable region in the middle. The Ser residue in the conserved region 1 and the Tyr residue in the variable region are important in regulating protein kinase C alpha (PKCα) membrane localization and focal adhesion formation. The objective of the current study was to investigate the role of syndecan-4 Ser and Tyr residues in combination with the GAG and N-glycosylated chains in turkey satellite cell proliferation, differentiation, fibroblast growth factor 2 (FGF2) responsiveness, and PKCα membrane localization. Site-directed mutagenesis was used to generate Ser and Tyr mutants with or without GAG and N-glycosylated chains. The wild type and mutant syndecan-4 constructs were transfected into turkey satellite cells. The over-expression of Ser and Tyr mutants increased cell proliferation and differentiation and decreased membrane localization of PKCα. Furthermore, Ser mutants enhanced cellular responsiveness to FGF2. The results from this study are the first demonstration of a role of syndecan-4 cytoplasmic domain Ser and Tyr residues in regulating satellite cell proliferation, differentiation, and the modulation of cellular responsiveness to FGF2.

  16. Habitat-specific population growth of a farmland bird.

    Directory of Open Access Journals (Sweden)

    Debora Arlt

    Full Text Available BACKGROUND: To assess population persistence of species living in heterogeneous landscapes, the effects of habitat on reproduction and survival have to be investigated. METHODOLOGY/PRINCIPAL FINDINGS: We used a matrix population model to estimate habitat-specific population growth rates for a population of northern wheatears Oenanthe oenanthe breeding in farmland consisting of a mosaic of distinct habitat (land use types. Based on extensive long-term data on reproduction and survival, habitats characterised by tall field layers (spring- and autumn-sown crop fields, ungrazed grasslands displayed negative stochastic population growth rates (log lambda(s: -0.332, -0.429, -0.168, respectively, that were markedly lower than growth rates of habitats characterised by permanently short field layers (pastures grazed by cattle or horses, and farmyards, log lambda(s: -0.056, +0.081, -0.059. Although habitats differed with respect to reproductive performance, differences in habitat-specific population growth were largely due to differences in adult and first-year survival rates, as shown by a life table response experiment (LTRE. CONCLUSIONS/SIGNIFICANCE: Our results show that estimation of survival rates is important for realistic assessments of habitat quality. Results also indicate that grazed grasslands and farmyards may act as source habitats, whereas crop fields and ungrazed grasslands with tall field layers may act as sink habitats. We suggest that the strong decline of northern wheatears in Swedish farmland may be linked to the corresponding observed loss of high quality breeding habitat, i.e. grazed semi-natural grasslands.

  17. Neighbors' problems, our problems: population growth in Central America.

    Science.gov (United States)

    Fox, R W

    1990-06-01

    A largely ignored issue, Central America faces its most pressing problem in its soaring population growth, one that is wreaking havoc on its economic and social infrastructures. Rising by a factor of 7, Central America's population -- presently 28.9 million -- is expected to reach 7.7 million by the year 2000, and 62.8 million by 2025. Typical of most of the Third World, Central America's population explosion stems from the fact that while the latter half of the 20th century has seen reductions of mortality rates, brought on by improvements of general health conditions, birth rates have remained excessively high. Despite moderate declines in the birth rate, Central American women still average 3-6 children. These demographic factors pose catastrophic consequences for Central America's natural resources, urban development and labor force. And they also threaten to increase migration to the US. Economic pressures have put great demands on the region's rain forests, exploited both for its resources and cleared away to create farmland. Today, only 40% of the original forest remains, and almost 3% more is destroyed annually. The area's capital cities have seen their populations increase 3-6 fold between 1950 and 1980. This explosion places further demands on already overburdened urban infrastructures, and has led to a mushrooming of squatter settlements. It has also led to a massive increase in the urban labor force which cannot be accommodated by the region's economies, which are in disarray due to falling export commodity earnings, limited natural resources, and scant investment capital. The economic woes could further increase the flow of workers to the US (15-20% of El Salvador's total population has already filed to the US). Historically, the region had attempted to offset population growth through economic development, but such expectations were not met, especially with the economic decline that wiped out gains made during the 1960s and 70s. Only recently have the

  18. Population growth is a variable open to change

    Science.gov (United States)

    Potts, M.

    2016-12-01

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

  19. Deterministic versus stochastic aspects of superexponential population growth models

    Science.gov (United States)

    Grosjean, Nicolas; Huillet, Thierry

    2016-08-01

    Deterministic population growth models with power-law rates can exhibit a large variety of growth behaviors, ranging from algebraic, exponential to hyperexponential (finite time explosion). In this setup, selfsimilarity considerations play a key role, together with two time substitutions. Two stochastic versions of such models are investigated, showing a much richer variety of behaviors. One is the Lamperti construction of selfsimilar positive stochastic processes based on the exponentiation of spectrally positive processes, followed by an appropriate time change. The other one is based on stable continuous-state branching processes, given by another Lamperti time substitution applied to stable spectrally positive processes.

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

    Directory of Open Access Journals (Sweden)

    Axel Kristinsson

    2016-06-01

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

  1. The Role of Human Capital and Population Growth in R&D-Based Models of Economic Growth

    OpenAIRE

    Holger Strulik

    2001-01-01

    Human capital accumulation is introduced in a growth model with R\\&D-driven expansion in variety and quality of intermediate goods andknowledge spillovers from both research activities. Economic growth is no longer uniquely tied to population growth as previous growth models without scale effects suggest. The model predicts that economic growth depends positively on the rate of human capital accumulation and positively or negatively on population growth and is therefore supported by empirical...

  2. Genomic growth curves of an outbred pig population

    Directory of Open Access Journals (Sweden)

    Fabyano Fonseca e Silva

    2013-01-01

    Full Text Available In the current post-genomic era, the genetic basis of pig growth can be understood by assessing SNP marker effects and genomic breeding values (GEBV based on estimates of these growth curve parameters as phenotypes. Although various statistical methods, such as random regression (RR-BLUP and Bayesian LASSO (BL, have been applied to genomic selection (GS, none of these has yet been used in a growth curve approach. In this work, we compared the accuracies of RR-BLUP and BL using empirical weight-age data from an outbred F2 (Brazilian Piau X commercial population. The phenotypes were determined by parameter estimates using a nonlinear logistic regression model and the halothane gene was considered as a marker for evaluating the assumptions of the GS methods in relation to the genetic variation explained by each locus. BL yielded more accurate values for all of the phenotypes evaluated and was used to estimate SNP effects and GEBV vectors. The latter allowed the construction of genomic growth curves, which showed substantial genetic discrimination among animals in the final growth phase. The SNP effect estimates allowed identification of the most relevant markers for each phenotype, the positions of which were coincident with reported QTL regions for growth traits.

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

    Science.gov (United States)

    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

  4. Deforestation driven by urban population growth and agricultural trade in the twenty-first century

    Science.gov (United States)

    Defries, Ruth S.; Rudel, Thomas; Uriarte, Maria; Hansen, Matthew

    2010-03-01

    Reducing atmospheric carbon emissions from tropical deforestation is at present considered a cost-effective option for mitigating climate change. However, the forces associated with tropical forest loss are uncertain. Here we use satellite-based estimates of forest loss for 2000 to 2005 (ref. 2) to assess economic, agricultural and demographic correlates across 41 countries in the humid tropics. Two methods of analysis-linear regression and regression tree-show that forest loss is positively correlated with urban population growth and exports of agricultural products for this time period. Rural population growth is not associated with forest loss, indicating the importance of urban-based and international demands for agricultural products as drivers of deforestation. The strong trend in movement of people to cities in the tropics is, counter-intuitively, likely to be associated with greater pressures for clearing tropical forests. We therefore suggest that policies to reduce deforestation among local, rural populations will not address the main cause of deforestation in the future. Rather, efforts need to focus on reducing deforestation for industrial-scale, export-oriented agricultural production, concomitant with efforts to increase yields in non-forested lands to satisfy demands for agricultural products.

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

    Science.gov (United States)

    Lambert, Guillaume; Kussell, Edo

    2013-03-01

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

  6. Minimal models of growth and decline of microbial populations.

    Science.gov (United States)

    Juška, Alfonsas

    2011-01-21

    Dynamics of growth and decline of microbial populations were analysed and respective models were developed in this investigation. Analysis of the dynamics was based on general considerations concerning the main properties of microorganisms and their interactions with the environment which was supposed to be affected by the activity of the population. Those considerations were expressed mathematically by differential equations or systems of the equations containing minimal sets of parameters characterizing those properties. It has been found that: (1) the factors leading to the decline of the population have to be considered separately, namely, accumulation of metabolites (toxins) in the medium and the exhaustion of resources; the latter have to be separated again into renewable ('building materials') and non-renewable (sources of energy); (2) decline of the population is caused by the exhaustion of sources of energy but no decline is predicted by the model because of the exhaustion of renewable resources; (3) the model determined by the accumulation of metabolites (toxins) in the medium does not suggest the existence of a separate 'stationary phase'; (4) in the model determined by the exhaustion of energy resources the 'stationary' and 'decline' phases are quite discernible; and (5) there is no symmetry in microbial population dynamics, the decline being slower than the rise. Mathematical models are expected to be useful in getting insight into the process of control of the dynamics of microbial populations. The models are in agreement with the experimental data.

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

    Science.gov (United States)

    Casey, Gregory; Galor, Oded

    2017-01-01

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

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

    Science.gov (United States)

    Gill, M S

    1987-01-01

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

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

    CERN Document Server

    Kapitza, Sergei P

    1996-01-01

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

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

    Science.gov (United States)

    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.

  11. FINGERNAIL GROWTH RATE IN A NORMAL CHINESE POPULATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To investigate fingernail growth rate (FNGR) role in the physiological or pathological status of the fingernails in normal Chinese population. Methods The FNGR was measured with vernier caliper. The data of 1 595 fingernails from 208 normal Chinese subjects (including 96 men and 112 women; age ranging from 14 to 78 years) were analyzed. Results The average FNGR was (0.104±0.027) mm per day. Higher growth rates were observed in males than in females, in the young individuals than in the old individuals, in summer than in winter, and in the right hand than in the left hand, respectively. The FNGR differed among fingernails and decreased in order of precedence: middle fingernails, index fingernails or ring fingernails, thumb and little fingernails. Conclusion FNGR was significantly associated with age, gender and temperature. Different fingernail grew at an individual speed.

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

    Science.gov (United States)

    Mays, S; Brickley, M; Ives, R

    2008-05-01

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

  13. Modelling population growth with delayed nonlocal reaction in 2-dimensions.

    Science.gov (United States)

    Liang, Dong; Wu, Jianhong; Zhang, Fan

    2005-01-01

    In this paper, we consider the population growth of a single species living in a two-dimensional spatial domain. New reaction-difusion equation models with delayed nonlocal reaction are developed in two-dimensional bounded domains combining diferent boundary conditions. The important feature of the models is the reflection of the joint efect of the difusion dynamics and the nonlocal maturation delayed efect. We consider and ana- lyze numerical solutions of the mature population dynamics with some wellknown birth functions. In particular, we observe and study the occurrences of asymptotically stable steady state solutions and periodic waves for the two-dimensional problems with nonlocal delayed reaction. We also investigate numerically the efects of various parameters on the period, the peak and the shape of the periodic wave as well as the shape of the asymptotically stable steady state solution.

  14. Population growth of Yellowstone grizzly bears: Uncertainty and future monitoring

    Science.gov (United States)

    Harris, R.B.; White, Gary C.; Schwartz, C.C.; Haroldson, M.A.

    2007-01-01

    Grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem of the US Rocky Mountains have recently increased in numbers, but remain vulnerable due to isolation from other populations and predicted reductions in favored food resources. Harris et al. (2006) projected how this population might fare in the future under alternative survival rates, and in doing so estimated the rate of population growth, 1983–2002. We address issues that remain from that earlier work: (1) the degree of uncertainty surrounding our estimates of the rate of population change (λ); (2) the effect of correlation among demographic parameters on these estimates; and (3) how a future monitoring system using counts of females accompanied by cubs might usefully differentiate between short-term, expected, and inconsequential fluctuations versus a true change in system state. We used Monte Carlo re-sampling of beta distributions derived from the demographic parameters used by Harris et al. (2006) to derive distributions of λ during 1983–2002 given our sampling uncertainty. Approximate 95% confidence intervals were 0.972–1.096 (assuming females with unresolved fates died) and 1.008–1.115 (with unresolved females censored at last contact). We used well-supported models of Haroldson et al. (2006) and Schwartz et al. (2006a,b,c) to assess the strength of correlations among demographic processes and the effect of omitting them in projection models. Incorporating correlations among demographic parameters yielded point estimates of λ that were nearly identical to those from the earlier model that omitted correlations, but yielded wider confidence intervals surrounding λ. Finally, we suggest that fitting linear and quadratic curves to the trend suggested by the estimated number of females with cubs in the ecosystem, and using AICc model weights to infer population sizes and λ provides an objective means to monitoring approximate population trajectories in addition to demographic

  15. The influence of satellite populations of emerald ash borer on projected economic costs in U.S. communities, 2010-2020.

    Science.gov (United States)

    Kovacs, Kent F; Mercader, Rodrigo J; Haight, Robert G; Siegert, Nathan W; McCullough, Deborah G; Liebhold, Andrew M

    2011-09-01

    The invasion spread of the emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is characterized by the formation of satellite populations that expand and coalesce with the continuously invading population front. As of January 2010, satellite infestations have been detected in 13 states and two Canadian provinces. Understanding how newly established satellite populations may affect economic costs can help program managers to justify and design prevention and control strategies. We estimate the economic costs caused by EAB for the 10-yr period from 2010 to 2020 for scenarios of fewer EAB satellite populations than those found from 2005 to 2010 and slower expansion of satellite populations found in 2009. We measure the projected discounted cost of treatment, removal, and replacement of ash trees (Fraxinus spp.) growing in managed landscapes in U.S. communities. Estimated costs for the base scenario with the full complement of satellites in 2005-2010 and no program to mitigate spread is $12.5 billion. Fewer EAB satellites from 2005 to 2010 delay economic costs of $1.0 to 7.4 billion. Slower expansion of 2009 satellite populations delays economic costs of $0.1 to 0.7 billion. Satellite populations that are both distant from the core EAB infestation and close to large urban areas caused more economic costs in our simulations than did other satellites. Our estimates of delayed economic costs suggest that spending on activities that prevent establishment of new satellite EAB populations or slow expansion of existing populations can be cost-effective and that continued research on the cost and effectiveness of prevention and control activities is warranted.

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

    Science.gov (United States)

    You Poh Seng Rao, B; Shantakumar, G

    1974-01-01

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

  17. [The metropolitan area of Guadalajara. The population growth transition].

    Science.gov (United States)

    Arroyo Alejandre, J

    1994-01-01

    The Guadalajara metropolitan area, containing approximately three million inhabitants in the municipios of Guadalajara, Zapopan, Tlaquepaque, Tonala, and El Salto, has high rates of population growth due to in-migration, natural increase, and annexation of localities. The average annual rate of growth declined from 6.8% in the 1950s to 2.6% in the 1980s. Despite the decline, which can be considered an indicator of transition, the increase in absolute numbers resulting from a 2.6% rate of growth amounts to 78,000 new inhabitants each year. A change has occurred in recent decades in the migratory patterns and urban spatial distribution of Western Mexico. In-migration to the Guadalajara metropolitan zone has slowed in both absolute and relative terms. Growth of smaller and intermediate sized cities is now more rapid than is that of the metropolitan zone. Surveys in Guadalajara indicate that the proportion of in-migrants from urban areas has increased substantially. Despite the slowing pace of growth, the Guadalajara metropolitan area faces serious problems of housing, land use, transport, and urban infrastructure and services in general. Because of rapid growth and the preponderance of young people among the migrants, the problems are likely to persist for some time. Population projections suggest that 66,000 new jobs will be needed during 1990-95 and 57,000 during 1995-2000, assuming no significant increases in the proportion of women who work. An average of 2500 hectares of land will be needed every five years, nearly equivalent to the total area of the city in 1940. The number of daily trips on urban transit is projected to increase from 6 million at present to 7 million in 2005. The daily load of solid waste is expected to increase from 4000 to 5000 tons in 2005. The economic structure of the city is also changing. Commerce and small and medium-sized manufacturing enterprises have lost their primacy and large national and transnational manufacturing and commercial

  18. Monitoring the Urban Growth of Dhaka (bangladesh) by Satellite Imagery in Flooding Risk Management Perspective

    Science.gov (United States)

    Bitelli, G.; Franci, F.; Mandanici, E.

    2013-01-01

    There is large consensus that demographic changes, the lack of appropriate environmental policies and sprawling urbanization result in high vulnerability and exposure to the natural disasters. This work reports some experiences of using multispectral satellite imagery to produce landuse/cover maps for the Dhaka city, the capital of Bangladesh, which is subject to frequent flooding events.The activity was conducted in collaboration with the non-profit organization ITHACA (Information Technology for Humanitarian Assistance, Cooperation and Action). The Landsat images acquired in 2000, 2002 and 2009 were used to evaluate the urban growth in order to support risk assessment studies; to identify areas routinely flooded during the monsoon season, the image of October 2009 (the most critical month for the effects of rain) was compared with two images acquired in January and February 2010. The analysis between 2000 and 2009 was able to quantify a very rapid growth of the metropolis, with an increase in built-up areas from 75 to 111 km2. The analysis highlights also a sharp rise of Bare soil class, likely related to the construction of embankments for the creation of new building space; consequently a decrease of cultivated land was observed. In particular, these artificial islands have been invading flooding areas. The change detection procedure also showed that the flooding in October 2009 affected about 20% (115 out of 591 km2) of the entire study area; furthermore these areas became wetlands and farmland over the next three/four months.

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

    Science.gov (United States)

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

    2015-07-14

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

  20. The vascular endothelial growth factor expression and vascular regeneration in infarcted myocardium by skeletal muscle satellite cells

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Background Myocardial infarction results in tissue necrosis, leading to cell loss and ultimately to cardiac failure. Implantation of skeletal muscle satellite cells into the scar area may compensate for the cell loss and provides a new strategy for infarct therapy. Vascular endothelial growth factor (VEGF) is a promising reagent for inducing myocardial angiogenesis. Skeletal myoblast transplantation has been shown to improve cardiac function in chronic heart failure models by regenerating muscle. We hypothesized that VEGF expression and vascular regeneration increased in infarcted myocardium by skeletal muscle satellite cells, which can promote vascular producing and improve survival environment in infarcted myocardium.Methods The skeletal muscle satellite cells were implanted into the infarcted myocardium in a model through ligated left anterior artery in Louis Inbrad Strain rat. Specimens were got for identifying the expression of VEGF and the density of vascular by immunochemical method at two weeks after implantation. Results The proliferation and differentiation of the skeletal muscle satellite cell was very well. The expression of VEGF was higher in the implanted group (146.83±2.49) than that in the control group (134.26±6.84) (P<0.05). The vascular density in the implanted group (13.00±1.51) was also higher than that in the control (10.68±1.79) (P<0.05). Conclusion The implanted satellite cell could excrete growth factor that would induce angiogenesis and improve cell survival environment in infarcted myocardium.

  1. Hawksbill satellite-tracking case study: Implications for remigration interval and population estimates

    Science.gov (United States)

    Sartain-Iverson, Autumn R.; Hart, Kristen M.; Fujisaki, Ikuko; Cherkiss, Michael S.; Pollock, Clayton; Lundgren, Ian; Hillis-Starr, Zandy

    2016-01-01

    Hawksbill sea turtles (Eretmochelys imbricata) are circumtropically distributed and listed as Critically Endangered by the IUCN (Meylan & Donnelly 1999; NMFS & USFWS 1993). To aid in population recovery and protection, the Hawksbill Recovery Plan identified the need to determine demographic information for hawksbills, such as distribution, abundance, seasonal movements, foraging areas (sections 121 and 2211), growth rates, and survivorship (section 2213, NMFS & USFWS 1993). Mark-recapture analyses are helpful in estimating demographic parameters and have been used for hawksbills throughout the Caribbean (e.g., Richardson et al. 1999; Velez-Zuazo et al. 2008); integral to these studies are recaptures at the nesting site as well as remigration interval estimates (Hays 2000). Estimates of remigration intervals (the duration between nesting seasons) are critical to marine turtle population estimates and measures of nesting success (Hays 2000; Richardson et al. 1999). Although hawksbills in the Caribbean generally show natal philopatry and nesting-site fidelity (Bass et al. 1996; Bowen et al. 2007), exceptions to this have been observed for hawksbills and other marine turtles (Bowen & Karl 2007; Diamond 1976; Esteban et al. 2015; Hart et al. 2013). This flexibility in choosing a nesting beach could therefore affect the apparent remigration interval and subsequently, region-wide population counts.

  2. Population Growth, Human Capital Expenditures and Economic Growth: A Macroeconometric Analysis

    OpenAIRE

    Aniceto C. Orbeta Jr

    1992-01-01

    The paper presents an econometrically estimated model where economic and demographic variables are determined simultaneously. It is used to quantify the importance of human capital expenditures in socioeconomic and demographic development as well as analyze the effects of rapid population growth on human capital expenditures. The simulation results indicate that human capital expenditures are important determinants of economic development, have appreciable negative effects on both fertility a...

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

    Science.gov (United States)

    Sharpless, J

    1995-01-01

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

  4. Plane of nutrition affects growth rate, organ size and skeletal muscle satellite cell activity in newborn calves.

    Science.gov (United States)

    MacGhee, M E; Bradley, J S; McCoski, S R; Reeg, A M; Ealy, A D; Johnson, S E

    2016-11-18

    Plane of nutrition effects on body, tissue and cellular growth in the neonatal calf are poorly understood. The hypothesis that a low plane of nutrition (LPN) would limit skeletal muscle size by reducing fibre growth and muscle progenitor cell activity was tested. At birth, calves were randomly assigned to either a LPN (20% CP, 20% fat; GE=1.9 Mcal/days) or a high plane of nutrition (HPN; 27% CP, 10% fat, GE = 3.8 Mcal/days) in a 2 × 3 factorial design to test the impact of diet on neonatal calf growth, organ weight and skeletal muscle morphometry with time. Groups of calves (n = 4 or 5) were euthanised at 2, 4 and 8 week of age and organ and empty carcass weights were recorded. Body composition was measured by DXA. Longissimus muscle (LM) fibre cross-sectional area (CSA), fibre/mm(2) and Pax7 were measured by immunohistology. Satellite cells were isolated at each time point and proliferation rates were measured by EdU incorporation. Calves fed a HPN had greater (p satellite cells per fibre. Proliferation rates of satellite cells isolated from HPN fed calves were greater (p satellite cell activity.

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

    Directory of Open Access Journals (Sweden)

    Komol Singha

    2013-01-01

    Full Text Available The study of population and economic growth has been the subject of intense debates between the two schools of thought. One relates to pessimistic opinion that population has a negative impact on economic growth while the other is convinced that the effect is positive. Recently, third group argues that the rise in population is neutral on economic growth. However, till date, the issue remains inconclusive. To analyse causality, using 51 years time series data of GDP and population growth, a Granger Causality Test was done and found that population growth causes neither GDP nor vice versa in India.

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

    Science.gov (United States)

    Saw, S

    1988-01-01

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

  7. Food shortages in sub-Saharan Africa and population growth.

    Science.gov (United States)

    Munisi, S E

    1982-12-01

    Food problems faced by sub-Saharan African nations center around the widening gap between food needs and availablity. Food shortages are suggested to originate from poor distribution and as a result of natural disasters; not as a consequence of population growth. Imperialism, colonialism, and neocolonial exploitation has encouraged African economic and cultural backwardness; a situation in which high population growth can have grave consequences. Fertility control is promoted by industrialized governments as a means of solving socioeconomic problems. However, fertility control may not be justified in many African nations which experience high infant mortality and labor intensive agriculture. Although the number of people who can be fed in any circumstance is ultimately finite, Africa's situation could be improved. If presently uninhabitable land was made suitable for settlement, land shortage from overpopulation would not be problematic for a long time. Modernization of agricultural practices could have a substantial impact of food production. At present, innovations are largely associated with the production of export crops which has often necessitated food imports. Food aid for relief in emergencies or for support of regions with chronic shortages is appropriate and beneficial, however, in some cases food aid can be detrimental, e.g., by lowering food prices thus burdening small farmers. Food aid tends to create dependency, not self-sufficiency. Malnutrition and hunger are symptoms of underdevelopment. At the policy level, a food and nutrition strategy should include rural development designed to improve income redistribution, agricultural modernization, and measures to influence the production of various foods to ensure a balanced diet, and nutrition and health intervention programs for vulnerable groups. In addition to overall agricultural development, 2 general recommendations are offered: increased production of staple food stuffs and a concentrated effort to

  8. Skeletal muscle satellite cells: mediators of muscle growth during development and implications for developmental disorders.

    Science.gov (United States)

    Dayanidhi, Sudarshan; Lieber, Richard L

    2014-11-01

    Satellite cells (SCs) are the muscle stem cells responsible for longitudinal and cross-sectional postnatal growth and repair after injury and which provide new myonuclei when needed. We review their morphology and contribution to development and their role in sarcomere and myonuclear addition. SCs, similar to other tissue stem cells, cycle through different states, such as quiescence, activation, and self-renewal, and thus we consider the signaling mechanisms involved in maintenance of these states. The role of the SC niche and their interactions with other cells, such as fibroblasts and the extracellular matrix, are all emerging as major factors that affect aging and disease. Interestingly, children with cerebral palsy appear to have a reduced SC number, which could play a role in their reduced muscular development and even in muscular contracture formation. Finally, we review the current information on SC dysfunction in children with muscular dystrophy and emerging therapies that target promotion of myogenesis and reduction of fibrosis. © 2014 Wiley Periodicals, Inc.

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

    Science.gov (United States)

    Ehrlich, I; Lui, F

    1997-01-01

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

  10. Modelling of Informal Settlement Growth with Satellite Data in Latakia City,Syria

    Directory of Open Access Journals (Sweden)

    Yahya Ghassoun

    2013-12-01

    , dynamics of change in land use/land cover and their impact have been studied. The satellite data (Landsat, IRS, and CORONA have been used. This study shows significant classes (Trees, Grass, Buildings, Water, Vacant, Roads in the land use/land cover which are found to change significantly during 1970 and 2005. Also rapid growth of informal settlements have been observed. Remote sensing images have been handled using GIS system to visualize the dynamics of the changes in land use/land cover. Finally the physical situation of the informal settlement has been studied and has been organized in three categories (Good, Medium and bad.

  11. Strong persistent growth differences govern individual performance and population dynamics in a tropical forest understorey palm

    NARCIS (Netherlands)

    Jansen, M.; Zuidema, P.A.; Anten, N.P.R.; Martínez-Ramos, M.

    2012-01-01

    1. Persistent variation in growth rate between individual plants can have strong effects on population dynamics as fast growers reach the reproductive size at an earlier age and thus potentially contribute more to population growth than slow growers. In tropical forests, such persistent growth diffe

  12. People of New Mexico: Size, Growth and Hispanic Population from the 1980 Census. Research Report 482.

    Science.gov (United States)

    Williams, James D.

    New Mexico, while small, is a state of great diversity in terms of size, growth, and Hispanic concentration of population. Data from the 1980 census indicate New Mexico is the 37th largest state with slightly more than 1.3 million persons and is ninth among the states in percentage of population growth. Growth comes from two demographic sources:…

  13. Determinism, noise, and spurious estimations in a generalised model of population growth

    NARCIS (Netherlands)

    De Vladar, H.P.; Pen, I.R.

    2007-01-01

    We study a generalised model of population growth in which the state variable is population growth rate instead of population size. Stochastic parametric perturbations, modelling phenotypic variability, lead to a Langevin system with two sources of multiplicative noise. The stationary probability di

  14. Insulin-like growth factor-I extends in vitro replicative life span of skeletal muscle satellite cells by enhancing G1/S cell cycle progression via the activation of phosphatidylinositol 3'-kinase/Akt signaling pathway

    Science.gov (United States)

    Chakravarthy, M. V.; Abraha, T. W.; Schwartz, R. J.; Fiorotto, M. L.; Booth, F. W.

    2000-01-01

    Interest is growing in methods to extend replicative life span of non-immortalized stem cells. Using the insulin-like growth factor I (IGF-I) transgenic mouse in which the IGF-I transgene is expressed during skeletal muscle development and maturation prior to isolation and during culture of satellite cells (the myogenic stem cells of mature skeletal muscle fibers) as a model system, we elucidated the underlying molecular mechanisms of IGF-I-mediated enhancement of proliferative potential of these cells. Satellite cells from IGF-I transgenic muscles achieved at least five additional population doublings above the maximum that was attained by wild type satellite cells. This IGF-I-induced increase in proliferative potential was mediated via activation of the phosphatidylinositol 3'-kinase/Akt pathway, independent of mitogen-activated protein kinase activity, facilitating G(1)/S cell cycle progression via a down-regulation of p27(Kip1). Adenovirally mediated ectopic overexpression of p27(Kip1) in exponentially growing IGF-I transgenic satellite cells reversed the increase in cyclin E-cdk2 kinase activity, pRb phosphorylation, and cyclin A protein abundance, thereby implicating an important role for p27(Kip1) in promoting satellite cell senescence. These observations provide a more complete dissection of molecular events by which increased local expression of a growth factor in mature skeletal muscle fibers extends replicative life span of primary stem cells than previously known.

  15. Insulin-like growth factor-I extends in vitro replicative life span of skeletal muscle satellite cells by enhancing G1/S cell cycle progression via the activation of phosphatidylinositol 3'-kinase/Akt signaling pathway

    Science.gov (United States)

    Chakravarthy, M. V.; Abraha, T. W.; Schwartz, R. J.; Fiorotto, M. L.; Booth, F. W.

    2000-01-01

    Interest is growing in methods to extend replicative life span of non-immortalized stem cells. Using the insulin-like growth factor I (IGF-I) transgenic mouse in which the IGF-I transgene is expressed during skeletal muscle development and maturation prior to isolation and during culture of satellite cells (the myogenic stem cells of mature skeletal muscle fibers) as a model system, we elucidated the underlying molecular mechanisms of IGF-I-mediated enhancement of proliferative potential of these cells. Satellite cells from IGF-I transgenic muscles achieved at least five additional population doublings above the maximum that was attained by wild type satellite cells. This IGF-I-induced increase in proliferative potential was mediated via activation of the phosphatidylinositol 3'-kinase/Akt pathway, independent of mitogen-activated protein kinase activity, facilitating G(1)/S cell cycle progression via a down-regulation of p27(Kip1). Adenovirally mediated ectopic overexpression of p27(Kip1) in exponentially growing IGF-I transgenic satellite cells reversed the increase in cyclin E-cdk2 kinase activity, pRb phosphorylation, and cyclin A protein abundance, thereby implicating an important role for p27(Kip1) in promoting satellite cell senescence. These observations provide a more complete dissection of molecular events by which increased local expression of a growth factor in mature skeletal muscle fibers extends replicative life span of primary stem cells than previously known.

  16. Growth in NOx emissions from power plants in China: bottom-up estimates and satellite observations

    Directory of Open Access Journals (Sweden)

    Y. Lei

    2012-01-01

    Full Text Available Using OMI (Ozone Monitoring Instrument tropospheric NO2 columns and a nested-grid 3-D global chemical transport model (GEOS-Chem, we investigated the growth in NOx emissions from coal-fired power plants and their contributions to the growth in NO2 columns in 2005–2007 in China. We first developed a unit-based power plant NOx emission inventory for 2005–2007 to support this investigation. The total capacities of coal-fired power generation have increased by 48.8% in 2005–2007, with 92.2% of the total capacity additions coming from generator units with size ≥300 MW. The annual NOx emissions from coal-fired power plants were estimated to be 8.11 Tg NO2 for 2005 and 9.58 Tg NO2 for 2007, respectively. The modeled summer average tropospheric NO2 columns were highly correlated (R2 = 0.79–0.82 with OMI measurements over grids dominated by power plant emissions, with only 7–14% low bias, lending support to the high accuracy of the unit-based power plant NOx emission inventory. The ratios of OMI-derived annual and summer average tropospheric NO2 columns between 2007 and 2005 indicated that most of the grids with significant NO2 increases were related to power plant construction activities. OMI had the capability to trace the changes of NOx emissions from individual large power plants in cases where there is less interference from other NOx sources. Scenario runs from GEOS-Chem model suggested that the new power plants contributed 18.5% and 10% to the annual average NO2 columns in 2007 in Inner Mongolia and North China, respectively. The massive new power plant NOx emissions significantly changed the local NO2 profiles, especially in less polluted areas. A sensitivity study found that changes of NO2 shape factors due to including new power plant emissions increased the summer average OMI tropospheric NO2 columns by 3.8–17.2% for six selected locations, indicating that the updated emission information could help to improve the satellite

  17. Growth in NOx emissions from power plants in China: bottom-up estimates and satellite observations

    Directory of Open Access Journals (Sweden)

    Y. Lei

    2012-05-01

    Full Text Available Using OMI (Ozone Monitoring Instrument tropospheric NO2 columns and a nested-grid 3-D global chemical transport model (GEOS-Chem, we investigated the growth in NOx emissions from coal-fired power plants and their contributions to the growth in NO2 columns in 2005–2007 in China. We first developed a unit-based power plant NOx emission inventory for 2005–2007 to support this investigation. The total capacities of coal-fired power generation have increased by 48.8% in 2005–2007, with 92.2% of the total capacity additions coming from generator units with size ≥300 MW. The annual NOx emissions from coal-fired power plants were estimated to be 8.11 Tg NO2 for 2005 and 9.58 Tg NO2 for 2007, respectively. The modeled summer average tropospheric NO2 columns were highly correlated (R2 = 0.79–0.82 with OMI measurements over grids dominated by power plant emissions, with only 7–14% low bias, lending support to the high accuracy of the unit-based power plant NOx emission inventory. The ratios of OMI-derived annual and summer average tropospheric NO2 columns between 2007 and 2005 indicated that most of the grids with significant NO2 increases were related to power plant construction activities. OMI had the capability to trace the changes of NOx emissions from individual large power plants in cases where there is less interference from other NOx sources. Scenario runs from GEOS-Chem model suggested that the new power plants contributed 18.5% and 10% to the annual average NO2 columns in 2007 in Inner Mongolia and North China, respectively. The massive new power plant NOx emissions significantly changed the local NO2 profiles, especially in less polluted areas. A sensitivity study found that changes of NO2 shape factors due to including new power plant emissions increased the summer average OMI tropospheric NO2 columns by 3.8–17.2% for six selected locations, indicating that the updated emission information could help to improve the satellite

  18. Satellite cell activation in stretched skeletal muscle and the role of nitric oxide and hepatocyte growth factor.

    Science.gov (United States)

    Tatsumi, Ryuichi; Liu, Xiaosong; Pulido, Antonio; Morales, Mark; Sakata, Tomowa; Dial, Sharon; Hattori, Akihito; Ikeuchi, Yoshihide; Allen, Ronald E

    2006-06-01

    In the present study, we examined the roles of hepatocyte growth factor (HGF) and nitric oxide (NO) in the activation of satellite cells in passively stretched rat skeletal muscle. A hindlimb suspension model was developed in which the vastus, adductor, and gracilis muscles were subjected to stretch for 1 h. Satellite cells were activated by stretch determined on the basis of 5-bromo-2'-deoxyuridine (BrdU) incorporation in vivo. Extracts from stretched muscles stimulated BrdU incorporation in freshly isolated control rat satellite cells in a concentration-dependent manner. Extracts from stretched muscles contained the active form of HGF, and the satellite cell-activating activity could be neutralized by incubation with anti-HGF antibody. The involvement of NO was investigated by administering nitro-L-arginine methyl ester (L-NAME) or the inactive enantiomer N(G)-nitro-D-arginine methyl ester HCl (D-NAME) before stretch treatment. In vivo activation of satellite cells in stretched muscle was not inhibited by D-NAME but was inhibited by L-NAME. The activity of stretched muscle extract was abolished by L-NAME treatment but could be restored by the addition of HGF, indicating that the extract was not inhibitory. Finally, NO synthase activity in stretched and unstretched muscles was assayed in muscle extracts immediately after 2-h stretch treatment and was found to be elevated in stretched muscle but not in stretched muscle from L-NAME-treated rats. The results of these experiments demonstrate that stretching muscle liberates HGF in a NO-dependent manner, which can activate satellite cells.

  19. Origin of the Different Architectures of the Jovian and Saturnian Satellite Systems

    OpenAIRE

    Sasaki, Takanori; Stewart, Glen R.; Ida, Shigeru

    2010-01-01

    The Jovian regular satellite system mainly consists of four Galilean satellites that have similar masses and are trapped in mutual mean motion resonances except for the outer satellite, Callisto. On the other hand, the Saturnian regular satellite system has only one big icy body, Titan, and a population of much smaller icy moons. We have investigated the origin of these major differences between the Jovian and Saturnian satellite systems by semi-analytically simulating the growth and orbital ...

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

    Science.gov (United States)

    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 ...

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

    Directory of Open Access Journals (Sweden)

    Wei-Bin Zhang

    2016-09-01

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

  2. Exploring the Population and Economic Growth Dynamics in Former Homeland Settlements between 1996 and 2011

    CSIR Research Space (South Africa)

    Ngidi, M

    2014-12-01

    Full Text Available and an age cohort analysis was used to indicate population movement. A simple linear regression was used to assess the relationship between population settlement patterns and economic growth on the prevalence of social grant recipients across settlements...

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

    National Research Council Canada - National Science Library

    Stutz, Aaron Jonas

    2014-01-01

    .... 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...

  4. Assessing the population coverage of a health demographic surveillance system using satellite imagery and crowd-sourcing.

    Science.gov (United States)

    Di Pasquale, Aurelio; McCann, Robert S; Maire, Nicolas

    2017-01-01

    Remotely sensed data can serve as an independent source of information about the location of residential structures in areas under demographic and health surveillance. We report on results obtained combining satellite imagery, imported from Bing, with location data routinely collected using the built-in GPS sensors of tablet computers, to assess completeness of population coverage in a Health and Demographic Surveillance System in Malawi. The Majete Malaria Project Health and Demographic Surveillance System, in Malawi, started in 2014 to support a project with the aim of studying the reduction of malaria using an integrated control approach by rolling out insecticide treated nets and improved case management supplemented with house improvement and larval source management. In order to support the monitoring of the trial a Health and Demographic Surveillance System was established in the area that surrounds the Majete Wildlife Reserve (1600 km2), using the OpenHDS data system. We compared house locations obtained using GPS recordings on mobile devices during the demographic surveillance census round with those acquired from satellite imagery. Volunteers were recruited through the crowdcrafting.org platform to identify building structures on the images, which enabled the compilation of a database with coordinates of potential residences. For every building identified on these satellite images by the volunteers (11,046 buildings identified of which 3424 (ca. 30%) were part of the censused area), we calculated the distance to the nearest house enumerated on the ground by fieldworkers during the census round of the HDSS. A random sample of buildings (85 structures) identified on satellite images without a nearby location enrolled in the census were visited by a fieldworker to determine how many were missed during the baseline census survey, if any were missed. The findings from this ground-truthing effort suggest that a high population coverage was achieved in the

  5. Influence of exercise contraction mode and protein supplementation on human skeletal muscle satellite cell content and muscle fiber growth.

    Science.gov (United States)

    Farup, Jean; Rahbek, Stine Klejs; Riis, Simon; Vendelbo, Mikkel Holm; Paoli, Frank de; Vissing, Kristian

    2014-10-15

    Skeletal muscle satellite cells (SCs) are involved in remodeling and hypertrophy processes of skeletal muscle. However, little knowledge exists on extrinsic factors that influence the content of SCs in skeletal muscle. In a comparative human study, we investigated the muscle fiber type-specific association between emergence of satellite cells (SCs), muscle growth, and remodeling in response to 12 wk unilateral resistance training performed as eccentric (Ecc) or concentric (Conc) resistance training ± whey protein (Whey, 19.5 g protein + 19.5 g glucose) or placebo (Placebo, 39 g glucose) supplementation. Muscle biopsies (vastus lateralis) were analyzed for fiber type-specific SCs, myonuclei, and fiber cross-sectional area (CSA). Following training, SCs increased with Conc in both type I and type II fibers (P hypertrophy correlated with whole muscle hypertrophy exclusively following Conc training (P eccentric resistance training while type II fiber hypertrophy was accentuated when combining concentric resistance training with whey protein supplementation.

  6. Influence of exercise contraction mode and protein supplementation on human skeletal muscle satellite cell content and muscle fiber growth

    DEFF Research Database (Denmark)

    Farup, Jean; Rahbek, Stine Klejs; Riis, Simon

    2014-01-01

    -specific association between emergence of satellite cells (SCs), muscle growth, and remodeling in response to 12 wk unilateral resistance training performed as eccentric (Ecc) or concentric (Conc) resistance training ± whey protein (Whey, 19.5 g protein + 19.5 g glucose) or placebo (Placebo, 39 g glucose......Skeletal muscle satellite cells (SCs) are involved in remodeling and hypertrophy processes of skeletal muscle. However, little knowledge exists on extrinsic factors that influence the content of SCs in skeletal muscle. In a comparative human study, we investigated the muscle fiber type......) supplementation. Muscle biopsies (vastus lateralis) were analyzed for fiber type-specific SCs, myonuclei, and fiber cross-sectional area (CSA). Following training, SCs increased with Conc in both type I and type II fibers (P

  7. 525 Population Growth, Hysteresis and Development Outcomes in ...

    African Journals Online (AJOL)

    The examples of the East Asian countries; especially the cases of China and. India are very ... increasing population indices; accounting for 15.2 percent of the world population ...... Economic Development (Eleventh Edition). Pearson ...

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

    Science.gov (United States)

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

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

  9. Latino Population Growth, Demographic Characteristics, and Educational Stagnation: An Examination of Recent Trends.

    Science.gov (United States)

    Chapa, Jorge; Valencia, Richard R.

    1993-01-01

    Presents data on rapid growth of the Latino population during the 1980s. Outlines ethnic and racial differences in educational attainment, family income, language status, age distribution, and other demographic variables. Discusses the impact of school segregation, growth of youth population, and low socioeconomic status on Latino access to…

  10. Urbanisation and Growth of Slum Population in Jharkhand: A Spatial Analysis

    Directory of Open Access Journals (Sweden)

    Rahul Harshwardhan

    2015-06-01

    Full Text Available The objective of this paper is to examine the relation between the pace of urbanisation and growth of slum population in Jharkhand. This paper also attempts to analyse the trends and patterns of growth of slum population at the district level in Jharkhand. In terms of urbanisation process of India, slums have become an integral part of urban scenario. In India, rapid growth of slums is the result of rural-urban migration of the rural poor to the cities/towns in search of employment in the last two decades. In the absence of any affordable housing, there has been growth of slums in the urban areas of the country. In India, out of a total population of 1.21 billion, 31.30% population resides in the urban areas, but 21.68% (61.8 million of the total urban population live in the slums. Slums are considered as a major problem within the urban areas, particularly in relation to the issues of transportation, population growth, health and safety. The developing states or regions of India are more prone to this problem due to the lack of infrastructural development and heavy urban population pressure. Like other states of India, Jharkhand too is facing the problem of slums. After its separation from Bihar in 2000, the rate of urbanisation and the rate of growth of slums had gone high. The study reveals that in 2001, there were only 11 urban centers consisting of slum population but in 2011, it reached to 31. The slum population registers 23.68% growth while the urban population growth stands at 32%. This paper is primarily based on secondary data collected from different governmental agencies, particularly the Census data of population to analyse the spatial distribution of slum population in the districts of Jharkhand. This study explores the changing urbanisation scenario in Jharkhand and the growth of slums with respect to it.

  11. Population Growth, Available Resources, and Quality of Life: China's Post-Reform Economic Development

    Institute of Scientific and Technical Information of China (English)

    Tim Futing Liao; Hua Qin

    2012-01-01

    Two opposing intellectual traditions and their contem- porary developments regarding the relations among population, available resources, and quality of life as reflected in economic growth are reviewed. What is at issue is whether population growth is detrimental to or beneficial for economic development. Neither of the extreme views gives a complete picture of the interplay among population, resources, and quality of life. Following previ- ous literature on the topic, this paper establishes a more balanced approach that considers the function linking population and quality of life not constant but variable and regards the limitedness of resources as not absolute but relative to regions and societies. The proposed approach is more flexible in better explaining the relation between population and economic growth. China is examined as a case in point to shed light on the interaction of population growth, economic development, and available resources, and its recent post-economic reform experiences showcase the appropriateness of the synthetic approach.

  12. Population growth, saving, interest rates and stagnation: Discussing the Eggertsson-Mehrotra model

    OpenAIRE

    Spahn, Peter

    2016-01-01

    Post Keynesian stagnation theory argues that slower population growth dampens consumption and investment. A New Keynesian OLG model derives an unemployment equilibrium due to a negative natural rate in a three-generations credit contract framework. Besides deleveraging or rising inequality, also a shrinking population is a triggering factor. In all cases, a saving surplus drives real interest rates down. In other OLG settings however, with bonds as stores of value, slower population growth, o...

  13. Estimating individual contributions to population growth: evolutionary fitness in ecological time

    OpenAIRE

    Coulson, T.; Benton, T. G.; Lundberg, Per; Dall, S.R.X.; Kendall, B E; Gaillard, J.M.

    2006-01-01

    Ecological and evolutionary change is generated by variation in individual performance. Biologists have consequently long been interested in decomposing change measured at the population level into contributions from individuals, the traits they express and the alleles they carry. We present a novel method of estimating individual contributions to population growth and changes in distributions of quantitative traits and alleles. An individual's contribution to population growth is an indi...

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

    Science.gov (United States)

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

    2015-01-01

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

  15. The Effects of Solar Maximum on the Earth's Satellite Population and Space Situational Awareness

    Science.gov (United States)

    Johnson, Nicholas L.

    2012-01-01

    The rapidly approaching maximum of Solar Cycle 24 will have wide-ranging effects not only on the number and distribution of resident space objects, but also on vital aspects of space situational awareness, including conjunction assessment processes. The best known consequence of high solar activity is an increase in the density of the thermosphere, which, in turn, increases drag on the vast majority of objects in low Earth orbit. The most prominent evidence of this is seen in a dramatic increase in space object reentries. Due to the massive amounts of new debris created by the fragmentations of Fengyun-1C, Cosmos 2251 and Iridium 33 during the recent period of Solar Minimum, this effect might reach epic levels. However, space surveillance systems are also affected, both directly and indirectly, historically leading to an increase in the number of lost satellites and in the routine accuracy of the calculation of their orbits. Thus, at a time when more objects are drifting through regions containing exceptionally high-value assets, such as the International Space Station and remote sensing satellites, their position uncertainties increase. In other words, as the possibility of damaging and catastrophic collisions increases, our ability to protect space systems is degraded. Potential countermeasures include adjustments to space surveillance techniques and the resetting of collision avoidance maneuver thresholds.

  16. Population Growth and Policies in Mega-Cities. Sao Paulo.

    Science.gov (United States)

    United Nations New York, NY. Dept. of Economic and Social Information and Policy Analysis.

    This document is one in a series of studies that focus on the population policies and plans of a number of mega-cities in developing countries. The object of the series is to examine the formulation, implementation, and evaluation of the population policies of mega-cities from a broad perspective, emphasizing the reciprocal links between…

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

    Science.gov (United States)

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

    2015-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Barry Edmonston

    2009-12-01

    Full Text Available The effect of changes in rates of mortality, fertility, and migration depend not only on the age-specific patterns and levels of these rates, but on the age structure of the population. In order to remove the influences of the age structure and concentrate on the impact of the demographic rates themselves, a common practice is to analyze the influences of the rates for a standard age structure. This paper adapts the general approach of using a standard age structure to a stationary population equivalent (SPE model, and analyzes current population change, using the SPE model, for provinces of Canada. Below-replacement fertility levels are only partially offset by net immigration. The SPE model evidences the decrease in the eventual provincial populations brought about by the below replacement fertility. Out-migration for some provinces to other areas of Canada accentuates their eventual population decreases.

  19. Ramet population ecology of Panicum virgatum in the field - Competitively random growth of ramets and foraging behavior of ramet populations

    Institute of Scientific and Technical Information of China (English)

    Xinguo Yang; Tianlong Wu; Xu Cheng

    2008-01-01

    The authors investigated the heterogeneous size patterns and dynamic growth of the ramet population of Panicum virgatum, a clonal caespitose plant, limited to the space occupied by a ramet bunch and the time of the ramet yearly life cycle, to understand the ecology of clonal caespitose plants in the field, where the ramet bunch generally consisted of more than one genet. Dynamic life tables for ramet populations were established by the replacement of living ramets at the present time with "dead" ones in past time. These tables revealed stable coexisting patterns of isometric and allometric growing processes of ramets in mass and height respectively, which approximately followed the historic trajectory of a density-independent population. The ecology of clonal caespitose plants is further discussed based on the competitively random growth of ramet individuals, including the scale of foraging behavior. In the field, the ramet population ecol-ogy of switchgrass may be a statistical result of competitively random growth of ramet individuals. The foraging behavior of a ramet population could then be presented as a process in which ramet individuals competed with each other for light and grew randomly, whileat the same time a relatively stable dynamic growth pattern was apparent at the level of the ramet population, and the functional leaves were placed properly in time and space.

  20. Life-history and spatial determinants of somatic growth dynamics in Komodo dragon populations.

    Directory of Open Access Journals (Sweden)

    Rebecca J Laver

    Full Text Available 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.

  1. Density Effects on Plant Height Growth and Inequality in Sunflower Populations

    Institute of Scientific and Technical Information of China (English)

    Sa Xiao; Shu-Yan Chen; Lu-Qiang Zhao; Gang Wang

    2006-01-01

    Comparisons between competing and non-competing sunflower (Helianthus annuus L.) populations demonstrate pronounced effects of density on plant height growth, height-to-crown width ratio, and a population's height inequality. In the present study, non-destructive measurements of height and the projected crown area of sunflower plants were taken at seven times from emergence to fruit maturation in even-aged monospecific stands with initial densities of 1, 4, 16, and 64 plants/m2. The mean height of populations increased and then decreased with increasing population density; the height inequalities of uncrowded populations decreased during stand growth, whereas the height inequalities of crowded populations decreased first and then increased during stand development. The interindividual relationships between the relative height growth rate and height within uncrowded populations became significantly negative during population growth, whereas these relationships were negative first and then became positive during the development of crowded populations. In the uncrowded populations, the static interindividual relationship between height-to-crown width ratio and volume was positive, whereas for the crowded population these relationships became negative with increasing competition for light. The data suggest that the plastic responses of plant height and height-to-crown width ratio to light competition will become more intense with increasing competition intensity. The results of the present study argue strongly for the importance of size-dependent individual-level plastic responses due to size-asymmetric light competition in generating the variations in population height inequality.

  2. Geographically distinct Ceratophyllum demersum populations differ in growth, photosynthetic responses and phenotypic plasticity to nitrogen availability

    DEFF Research Database (Denmark)

    Hyldgaard, Benita; Sorrell, Brian Keith; Olesen, Birgit

    2012-01-01

    from New Zealand (NZ) and a noninvasive population from Denmark (DK). The populations were compared with a focus on both morphological and physiological traits. The NZ population had higher relative growth rates (RGRs) and photosynthesis rates (Pmax) (range: RGR, 0.06–0.08 per day; Pmax, 200–395 µmol O...

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

    Directory of Open Access Journals (Sweden)

    Edmonston, Barry

    2009-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Xiao-Yu Chang

    Full Text Available 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.

  6. The Transverse velocity of the Andromeda system, derived from the M31 satellite population

    CERN Document Server

    Salomon, J -B; Famaey, B; Martin, N F; Lewis, G F

    2015-01-01

    We present a dynamical measurement of the tangential motion of the Andromeda system, the ensemble consisting of the Andromeda Galaxy (M31) and its satellites. The system is modelled as a structure with cosmologically-motivated velocity dispersion and density profiles, and we show that our method works well when tested using the most massive substructures in high-resolution {\\Lambda} Cold Dark Matter ({\\Lambda}CDM) simulations. Applied to the sample of 40 currently-known galaxies of this system, we find a value for the transverse velocity of 164.4 +/- 61.8 km/s (v_{East} = -111.5 +/- 70.2 km/s and v{North} = 99.4 +/- 60.0 km/s), significantly higher than previous estimates of the proper motion of M31 itself. This result has significant implications on estimates of the mass of the Local Group, as well as on its past and future history.

  7. Population size, survival, growth, and movements of Rana sierrae

    Science.gov (United States)

    Fellers, Gary M.; Kleeman, Patrick M.; Miller, David A. W.; Halstead, Brian J.; Link, William

    2013-01-01

    Based on 2431 captures of 757 individual frogs over a 9-yr period, we found that the population of R. sierrae in one meadow–stream complex in Yosemite National Park ranged from an estimated 45 to 115 adult frogs. Rana sierrae at our relatively low elevation site (2200 m) grew at a fast rate (K = 0.73–0.78), had high overwintering survival rates (44.6–95%), lived a long time (up to 16 yr), and tended to be fairly sedentary during the summer (100% minimum convex polygon annual home ranges of 139 m2) but had low year-to-year site fidelity. Even though the amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) has been present in the population for at least 13 yr, there was no clear downward trend as might be expected from reports of R. sierrae population declines associated with Bd or from reports of widespread population decline of R. sierrae throughout its range.

  8. Rapid Population Growth and its Implication for Malawi

    African Journals Online (AJOL)

    type and technology as constraints on agricultural output, research has ... anization, modern fertilizers and improved seeds, ... Population and Human Resources Development Unit,. Office of ... income and employment, health and education,.

  9. Understanding contributions of cohort effects to growth rates of fluctuating populations.

    Science.gov (United States)

    Wittmer, Heiko U; Powell, Roger A; King, Carolyn M

    2007-09-01

    1. Understanding contributions of cohort effects to variation in population growth of fluctuating populations is of great interest in evolutionary biology and may be critical in contributing towards wildlife and conservation management. Cohort-specific contributions to population growth can be evaluated using age-specific matrix models and associated elasticity analyses. 2. We developed age-specific matrix models for naturally fluctuating populations of stoats Mustela erminea in New Zealand beech forests. Dynamics and productivity of stoat populations in this environment are related to the 3-5 year masting cycle of beech trees and consequent effects on the abundance of rodents. 3. The finite rate of increase (lambda) of stoat populations in New Zealand beech forests varied substantially, from 1.98 during seedfall years to 0.58 during post-seedfall years. Predicted mean growth rates for stoat populations in continuous 3-, 4- or 5-year cycles are 0.85, 1.00 and 1.13. The variation in population growth was a consequence of high reproductive success of females during seedfall years combined with low survival and fertility of females of the post-seedfall cohort. 4. Variation in population growth was consistently more sensitive to changes in survival rates both when each matrix was evaluated in isolation and when matrices were linked into cycles. Relative contributions to variation in population growth from survival and fertility, especially in 0-1-year-old stoats, also depend on the year of the cycle and the number of transitional years before a new cycle is initiated. 5. Consequently, management strategies aimed at reducing stoat populations that may be best during one phase of the beech seedfall cycle may not be the most efficient during other phases of the cycle. We suggest that management strategies based on elasticities of vital rates need to consider how population growth rates vary so as to meet appropriate economic and conservation targets.

  10. Kinematic evidence of satellite galaxy populations in the potential wells of first-ranked cluster galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Cowie, L.L.; Hu, E.M.

    1986-06-01

    The velocities of 38 centrally positioned galaxies (r much less than 100 kpc) were measured relative to the velocity of the first-ranked galaxy in 14 rich clusters. Analysis of the velocity distribution function of this sample and of previous data shows that the population cannot be fit by a single Gaussian. An adequate fit is obtained if 60 percent of the objects lie in a Gaussian with sigma = 250 km/s and the remainder in a population with sigma = 1400 km/s. All previous data sets are individually consistent with this conclusion. This suggests that there is a bound population of galaxies in the potential well of the central galaxy in addition to the normal population of the cluster core. This is taken as supporting evidence for the galactic cannibalism model of cD galaxy formation. 14 references.

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Agustino Martínez-Antonio

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

  13. Population growth and economic development in the very long run: a simulation model of three revolutions.

    Science.gov (United States)

    Steinmann, G; Komlos, J

    1988-08-01

    The authors propose an economic model capable of simulating the 4 main historical stages of civilization: hunting, agricultural, industrial, and postindustrial. An output-maximizing society to respond to changes in factor endowments by switching technologies. Changes in factor proportions arise through population growth and capital accumulation. A slow rate of exogenous technical process is assumed. The model synthesizes Malthusian and Boserupian notions of the effect of population growth on per capita output. Initially the capital-diluting effect of population growth dominates. As population density increases, however, and a threshold is reached, the Boserupian effect becomes crucial, and a technological revolution occurs. The cycle is thereafter repeated. After the second economic revolution, however, the Malthusian constraint dissolves permanently, as population growth can continue without being constrained by diminishing returns to labor. By synthesizing Malthusian and Boserupian notions, the model is able to capture the salient features of economic development in the very long run.

  14. Synergistic Use of Nighttime Satellite Data, Electric Utility Infrastructure, and Ambient Population to Improve Power Outage Detections in Urban Areas

    Directory of Open Access Journals (Sweden)

    Tony A. Cole

    2017-03-01

    Full Text Available Natural and anthropogenic hazards are frequently responsible for disaster events, leading to damaged physical infrastructure, which can result in loss of electrical power for affected locations. Remotely-sensed, nighttime satellite imagery from the Suomi National Polar-orbiting Partnership (Suomi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS Day/Night Band (DNB can monitor power outages in disaster-affected areas through the identification of missing city lights. When combined with locally-relevant geospatial information, these observations can be used to estimate power outages, defined as geographic locations requiring manual intervention to restore power. In this study, we produced a power outage product based on Suomi-NPP VIIRS DNB observations to estimate power outages following Hurricane Sandy in 2012. This product, combined with known power outage data and ambient population estimates, was then used to predict power outages in a layered, feedforward neural network model. We believe this is the first attempt to synergistically combine such data sources to quantitatively estimate power outages. The VIIRS DNB power outage product was able to identify initial loss of light following Hurricane Sandy, as well as the gradual restoration of electrical power. The neural network model predicted power outages with reasonable spatial accuracy, achieving Pearson coefficients (r between 0.48 and 0.58 across all folds. Our results show promise for producing a continental United States (CONUS- or global-scale power outage monitoring network using satellite imagery and locally-relevant geospatial data.

  15. Satellite Communications

    CERN Document Server

    Pelton, Joseph N

    2012-01-01

    The field of satellite communications represents the world's largest space industry. Those who are interested in space need to understand the fundamentals of satellite communications, its technology, operation, business, economic, and regulatory aspects. This book explains all this along with key insights into the field's future growth trends and current strategic challenges. Fundamentals of Satellite Communications is a concise book that gives all of the key facts and figures as well as a strategic view of where this dynamic industry is going. Author Joseph N. Pelton, PhD, former Dean of the International Space University and former Director of Strategic Policy at Intelstat, presents a r

  16. Seed dispersal by pulp consumers, not "legitimate" seed dispersers, increases Guettarda viburnoides population growth.

    Science.gov (United States)

    Loayza, Andrea P; Knight, Tiffany

    2010-09-01

    We examined the effect of seed dispersal by Purplish Jays (Cyanocorax cyanomelas; pulp consumers) and the Chestnut-eared Araçari (Pteroglossus castanotis; "legitimate" seed dispersers) on population growth of the small tree Guettarda viburnoides (Rubiaceae) in northeastern Bolivian savannas. Because each bird species differs with respect to feeding and post-feeding behavior, we hypothesized that seed dispersal by each species will contribute differently to the rate of increase of G. viburnoides, but that seed dispersal by either species will increase population growth when compared to a scenario with no seed dispersal. To examine the effects of individual dispersers on the future population size of G. viburnoides, we projected population growth rate using demographic models for G. viburnoides that explicitly incorporate data on quantitative and qualitative aspects of seed dispersal by each frugivore species. Our model suggests that seed dispersal by C. cyanomelas leads to positive population growth of G. viburnoides, whereas seed dispersal by P. castanotis has a detrimental effect on the population growth of this species. To our knowledge, this is the first study to report negative effects of a "legitimate" seed disperser on the population dynamics of the plant it consumes. Our results stress the importance of incorporating frugivore effects into population projection matrices, to allow a comprehensive analysis of the effectiveness of different dispersers for plant population dynamics.

  17. Geographic after-tax real income differentials and population growth rates.

    Science.gov (United States)

    Alexander, G; Cebula, R J; Koch, J V

    1990-03-01

    "The purpose of this [one-page] note is to empirically investigate the impact of geographic after-tax real income differentials on geographic population growth rate differentials. The focus is on population growth rates in Florida's 67 counties over the period 1980-88." The authors conclude that "even after allowing for a variety of other location-influencing factors, including coastal access, after-tax real income differentials exercise a positive and significant impact on population growth rate differentials among Florida's counties."

  18. The Relationship Among Electricity Consumption, Economic Growth and Population in Developing Countries

    Directory of Open Access Journals (Sweden)

    Betül İSMİÇ

    2015-06-01

    Full Text Available The importance of electiricity as a type of energy is the main obejective of this study. This study aims to test the relationship between variables of electricity consumption, economic growth and population for 8 developing countries according to the IMF list. Data were analyzed for 8 countries for 1990-2012 period to test the direction and impact of economic growth and population on electricity consumption by using panel data analysis. Our model is analyzed through Swamy’s Random Coefficient Model and Seemingly Unrelated Model; the positive effect of economic growth on electricity consumption is observed and the effect of population seems insignificant for 2 countries.

  19. Population growth through history and the escape from the Malthusian trap: a homeostatic simulation model.

    Science.gov (United States)

    Artzrouni, M; Komlos, J

    1985-01-01

    "A Malthusian simulation model is proposed to describe the growth of human population from the Neolithic through the Industrial Revolution. The economy is composed of a subsistence sector and a capital-producing sector. Our model captures the 'incessant contest' between population growth and the means of subsistence. When the per capita agricultural output falls below a biological minimum, the growth rate of the population is subject, in a random fashion, to perturbations that can take on disastrous proportions." It is suggested that "the slow accumulation of capital (and the buildup of the population of the capital-producing sector) eventually enables the population to overcome the constraints of the hostile economic environment. Our simulations (complete with confidence intervals) yield numerically realistic estimates of the population that eventually escapes from the Malthusian menace and grows unhindered during the Industrial Revolution." (summary in FRE, ITA)

  20. Decades of Urban Growth and Development on Deltas; Comparative Global Analysis of Night Lights and Population

    Science.gov (United States)

    Small, C.; Elvidge, C.; Yetman, G.; Baugh, K.; MacManus, K.

    2016-12-01

    It is well-known that coastal zones in general, and deltas in particular, are among the most densely populated environments on Earth. Decades of satellite imagery offer spatially explicit observations of the changing land use and development of deltas worldwide. Stable night lights provide globally consistent proxies for lighted development associated with a variety of human settlement types. Gridded census enumerations provide geospatial depictions of human population density associated with residential population distributions. Recent improvements in both night light imaging and census data resolution allow us to compare stable night light and residential population density with much greater spatial correspondence than previously possible. We use night light brightness from the Visible/Infrared Imaging Radiometer Suite (VIIRS) on the NASA/NOAA Suomi satellite and population density grids from the NASA SEDAC Gridded Population of the World v.4 (GPWv4) product to derive density/intensity transfer functions for a wide range of urban/rural gradients worldwide. These transfer functions provide the basis for spatial disaggregation of population using the higher resolution night light imagery in areas where census data lack the resolution for meaningful analysis of population and coastal hazard. Disaggregated population maps are combined with digital elevation models to estimate current population distributions with elevation and fluvial proximity for several of the world's most densely populated deltas. In addition, we use DMSP-OLS night light composites to map changes in lighted development on these deltas since 1992. Landsat imagery is then used to map the land cover changes associated with increases in night light brightness on these deltas. The result allows for spatially explicit comparisons of development patterns in different types of deltaic environments. We present a generalized methodology for mapping development and land cover with sufficient detail and

  1. Scaling relationship for NO2 pollution and urban population size: a satellite perspective.

    Science.gov (United States)

    Lamsal, L N; Martin, R V; Parrish, D D; Krotkov, N A

    2013-07-16

    Concern is growing about the effects of urbanization on air pollution and health. Nitrogen dioxide (NO2) released primarily from combustion processes, such as traffic, is a short-lived atmospheric pollutant that serves as an air-quality indicator and is itself a health concern. We derive a global distribution of ground-level NO2 concentrations from tropospheric NO2 columns retrieved from the Ozone Monitoring Instrument (OMI). Local scaling factors from a three-dimensional chemistry-transport model (GEOS-Chem) are used to relate the OMI NO2 columns to ground-level concentrations. The OMI-derived surface NO2 data are significantly correlated (r = 0.69) with in situ surface measurements. We examine how the OMI-derived ground-level NO2 concentrations, OMI NO2 columns, and bottom-up NOx emission inventories relate to urban population. Emission hot spots, such as power plants, are excluded to focus on urban relationships. The correlation of surface NO2 with population is significant for the three countries and one continent examined here: United States (r = 0.71), Europe (r = 0.67), China (r = 0.69), and India (r = 0.59). Urban NO2 pollution, like other urban properties, is a power law scaling function of the population size: NO2 concentration increases proportional to population raised to an exponent. The value of the exponent varies by region from 0.36 for India to 0.66 for China, reflecting regional differences in industrial development and per capita emissions. It has been generally established that energy efficiency increases and, therefore, per capita NOx emissions decrease with urban population; here, we show how outdoor ambient NO2 concentrations depend upon urban population in different global regions.

  2. Core-satellite populations and seasonality of water meter biofilms in a metropolitan drinking water distribution system.

    Science.gov (United States)

    Ling, Fangqiong; Hwang, Chiachi; LeChevallier, Mark W; Andersen, Gary L; Liu, Wen-Tso

    2016-03-01

    Drinking water distribution systems (DWDSs) harbor the microorganisms in biofilms and suspended communities, yet the diversity and spatiotemporal distribution have been studied mainly in the suspended communities. This study examined the diversity of biofilms in an urban DWDS, its relationship with suspended communities and its dynamics. The studied DWDS in Urbana, Illinois received conventionally treated and disinfected water sourced from the groundwater. Over a 2-year span, biomass were sampled from household water meters (n=213) and tap water (n=20) to represent biofilm and suspended communities, respectively. A positive correlation between operational taxonomic unit (OTU) abundance and occupancy was observed. Examined under a 'core-satellite' model, the biofilm community comprised 31 core populations that encompassed 76.7% of total 16 S rRNA gene pyrosequences. The biofilm communities shared with the suspended community highly abundant and prevalent OTUs, which related to methano-/methylotrophs (i.e., Methylophilaceae and Methylococcaceae) and aerobic heterotrophs (Sphingomonadaceae and Comamonadaceae), yet differed by specific core populations and lower diversity and evenness. Multivariate tests indicated seasonality as the main contributor to community structure variation. This pattern was resilient to annual change and correlated to the cyclic fluctuations of core populations. The findings of a distinctive biofilm community assemblage and methano-/methyltrophic primary production provide critical insights for developing more targeted water quality monitoring programs and treatment strategies for groundwater-sourced drinking water systems.

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

    Science.gov (United States)

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

    2010-06-01

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

  4. The Revival of Population Growth in Nonmetropolitan America.

    Science.gov (United States)

    Beale, Calvin L.

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

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

    African Journals Online (AJOL)

    Dr Ike

    in the good life and well being of the people in that society, thus .... and people have to travel long distances to get to school. Where .... and in the process may end up raising an unwieldy family size .... classrooms, equipment, laboratories, books and other teaching ... And what is more, the dense population of the country,.

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

    Directory of Open Access Journals (Sweden)

    Neeme Lumi

    2014-01-01

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

  7. Cougar predation and population growth of sympatric mule deer and white-tailed deer

    National Research Council Canada - National Science Library

    Robinson H.S; Wielgus R.B; Gwilliam J.C

    2002-01-01

    ...), recruitment, and cause-specific adult ( 1 year old) mortality rate for sympatric mule deer and white-tailed deer in south-central British Columbia to assess population growth for each species...

  8. Metropolitan population growth and distribution in the American South, 1970-1990.

    Science.gov (United States)

    Gihula, T J

    1994-11-01

    "Southern Metropolitan Statistical Areas (MSA) are rated among the nation's leaders in [U.S.] population growth in recent decades. Growth and rankings of MSAs are examined using Pannell's (1974) method. A linear rank-size pattern of cities is revealed, with centers of greatest population growing larger while smaller centers follow with proportionally smaller population changes. A regression model provided some support for the contention that city sizes affect city growth rates. Additional factors in southern metropolitan growth and decline were considered. Introduction of a labor cost factor into the regression model provided moderate support in accounting for variation in MSA growth rates. Several MSAs grew at rates predicted by the regression model while others performed differently than expected. Explanations for variations are presented for selected MSAs." excerpt

  9. [Population development and economic growth. A simulation analysis for Switzerland].

    Science.gov (United States)

    Schmidt, C; Straubhaar, T

    1996-01-01

    "A simulation exercise of a general equilibrium model for Switzerland makes clear that the macroeconomic impacts of aging populations are not very strong. There is no need for urgent policy actions to avoid severe negative economic consequences....However, the aging of population affects negatively the net income of the active labor force. An increasing share of their gross salaries goes to the retirement system to finance the pension payments of a growing number of pensioners. Attempts to moderate the elderly dependency ratio would lower this burden for the active labor force. Options are an increase of the female participation rate, an increase of the labor participation rate of the elderly--[which] also means a higher retirement age--and an increasing flow of immigrants. But socioeconomic problems might probably generate practical limits on the extent to which immigration can be increased." (SUMMARY IN ENG AND FRE) excerpt

  10. Survival, recruitment, and population growth rate of an important mesopredator: the northern raccoon.

    Directory of Open Access Journals (Sweden)

    Elizabeth M Troyer

    Full Text Available Populations of mesopredators (mid-sized mammalian carnivores are expanding in size and range amid declining apex predator populations and ever-growing human presence, leading to significant ecological impacts. Despite their obvious importance, population dynamics have scarcely been studied for most mesopredator species. Information on basic population parameters and processes under a range of conditions is necessary for managing these species. Here we investigate survival, recruitment, and population growth rate of a widely distributed and abundant mesopredator, the northern raccoon (Procyon lotor, using Pradel's temporal symmetry models and >6 years of monthly capture-mark-recapture data collected in a protected area. Monthly apparent survival probability was higher for females (0.949, 95% CI = 0.936-0.960 than for males (0.908, 95% CI = 0.893-0.920, while monthly recruitment rate was higher for males (0.091, 95% CI = 0.078-0.106 than for females (0.054, 95% CI = 0.042-0.067. Finally, monthly realized population growth rate was 1.000 (95% CI = 0.996-1.004, indicating that our study population has reached a stable equilibrium in this relatively undisturbed habitat. There was little evidence for substantial temporal variation in population growth rate or its components. Our study is one of the first to quantify survival, recruitment, and realized population growth rate of raccoons using long-term data and rigorous statistical models.

  11. A novel approach for estimating growth phases and parameters of bacterial population in batch culture

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Huaiqiang; LIU; Yuqing; LIU; Bo; GAO; Peiji

    2006-01-01

    Using mathematical analysis, a new method has been developed for studying the growth kinetics of bacterial populations in batch culture. First, sampling data were smoothed with the spline interpolation method. Second, the instantaneous rates were derived by numerical differential techniques and finally, the derived data were fitted with the Gaussian function to obtain growth parameters. We named this the Spline-Numerical-Gaussian or SNG method. This method yielded more accurate estimates of the growth rates of bacterial populations and new parameters. It was possible to divide the growth curve into four different but continuous phases based on changes in the instantaneous rates. The four phases are the accelerating growth phase, the constant growth phase, the decelerating growth phase and the declining phase. Total DNA content was measured by flow cytometry and varied depending on the growth phase. The SNG system provides a very powerful tool for describing the kinetics of bacterial population growth. The SNG method avoids the unrealistic assumptions generally used in the traditional growth equations.

  12. The Visible Minority Population in Canada: A Review of Numbers, Growth and Labour Force Issues

    Directory of Open Access Journals (Sweden)

    John Samuel

    2006-12-01

    Full Text Available In this paper, the Visible Minority Population in Canada: Numbers, Growth and Labour Force Issues, the characteristics of the visible minority population and labour force are examined including those employed by firms under the Legislated Employment Equity Program and the Federal Contractors Program. The future growth of the visible minority labour force and the socio-economic impact of the findings are discussed along with their implications.

  13. Trend shifts in satellite-derived vegetation growth in Central Eurasia, 1982-2013.

    Science.gov (United States)

    Xu, Hao-Jie; Wang, Xin-Ping; Yang, Tai-Bao

    2017-02-01

    Central Eurasian vegetation is critical for the regional ecological security and the global carbon cycle. However, climatic impacts on vegetation growth in Central Eurasia are uncertain. The reason for this uncertainty lies in the fact that the response of vegetation to climate change showed nonlinearity, seasonality and differences among plant functional types. Based on remotely sensed vegetation index and in-situ meteorological data for the years 1982-2013, in conjunction with the latest land cover type product, we analyzed how vegetation growth trend varied across different seasons and evaluated vegetation response to climate variables at regional, biome and pixel scales. We found a persistent increase in the growing season NDVI over Central Eurasia during 1982-1994, whereas this greening trend has stalled since the mid-1990s in response to increased water deficit. The stalled trend in the growing season NDVI was largely attributed by summer and autumn NDVI changes. Enhanced spring vegetation growth after 2002 was caused by rapid spring warming. The response of vegetation to climatic factors varied in different seasons. Precipitation was the main climate driver for the growing season and summer vegetation growth. Changes in temperature and precipitation during winter and spring controlled the spring vegetation growth. Autumn vegetation growth was mainly dependent on the vegetation growth in summer. We found diverse responses of different vegetation types to climate drivers in Central Eurasia. Forests were more responsive to temperature than to precipitation. Grassland and desert vegetation responded more strongly to precipitation than to temperature in summer but more strongly to temperature than to precipitation in spring. In addition, the growth of desert vegetation was more dependent on winter precipitation than that of grasslands. This study has important implications for improving the performance of terrestrial ecosystem models to predict future vegetation

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

    NARCIS (Netherlands)

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

    1996-01-01

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

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

    NARCIS (Netherlands)

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

    2002-01-01

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

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

    NARCIS (Netherlands)

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

    2002-01-01

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

  17. Barium Strontium Titanate Thin Film Growth with rotational speed variation as a satellite temperature sensor prototype

    Science.gov (United States)

    Mulyadi; Rika, W.; Sulidah; Irzaman; Hardhienata, Hendradi

    2017-01-01

    Barium Strontium Titanate(BST) is a promising material for sensor devices such as temperature and infrared sensor. BaxSr1-xTiO3 thin films with affordable Si substrate were prepared by chemical solution deposition method and spin coating technique for 30 seconds with variation in rotation speed (3000 rpm, 5500 rpm and 8000 rpm). A high baking temperature at 8500C has been used for 15 hours during the annealing process. The thickness of BST film was calculated via gravimetric calculation. USB 2000 VIS-NIR was used to characterize the optical properties of BST thin film. The obtained reflectance curve showed that the most reflected wavelengths were in the range of 408-452 nm respectively. The result of the optical film characterization is very important for further development as a sensor in satellite technology.

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

    Directory of Open Access Journals (Sweden)

    Cox Murray P

    2011-04-01

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

  19. Active population growth and immigration hypotheses in Western Europe.

    Science.gov (United States)

    Feld, S

    2000-03-01

    The paper examines, in respect of 12 Western European countries over a period of 20 years, the widely held view that any decline in their working population should be offset by greater reliance on immigrant labor. This research, based on demographic projections and forecasts regarding labor market participation rates by age and sex for each of the countries concerned, focuses on the two most likely scenarios. It appears that only Italy will be faced with a fall in its working population. All other western countries will either maintain the same level or, more generally, see their workforce grow substantially. Accordingly, the authors may safely assert that there is no risk of a shortage of workers between now and the year 2020, and that an increasing supply of labor will render reliance on a greater influx of immigrant workers unnecessary. The second part analyses changes in the structure of the demand for labor. The authors deal chiefly with the phenomenon of the concentration of foreign manpower in each sector, its flexibility and mobility in a context of unemployment, as well as the impact of new technologies and globalization on the main determinants of international migration of labor.

  20. Effect of the population heterogeneity on growth behavior and its estimation

    Institute of Scientific and Technical Information of China (English)

    ZHANG HuaiQiang; LU LiLi; YAN XueLan; GAO PeiJi

    2007-01-01

    Different types of the Logistic model are constructed based on a simple assumption that the microbial populations are all composed of homogeneous members and consequently, the condition of design for the initial value of these models has to be rather limited in the case of N(t0)=N0. Therefore, these models cannot distinguish the dynamic behavior of the populations possessing the same N0 from heterogeneous phases. In fact, only a certain ratio of the cells in a population is dividing at any moment during growth progress, termed as θ, and thus, dN/dt not only depends on N, but also on θ. So θis a necessary element for the condition design of the initial value. Unfortunately, this idea has long been neglected in widely used growth models. However, combining together the two factors (N0 and θ) into the initial value often leads to the complexity in the mathematical solution. This difficulty can be overcome by using instantaneous rates (Vinst) to express growth progress. Previous studies in our laboratory suggested that the Vinst curve of the bacterial populations all showed a Guassian function shape and thus,the different growth phases can be reasonably distinguished. In the present study, the Gaussian distribution function was transformed approximately into an analytical form (Yi = αe[-0.5(xi-x0/b)2]) that can be conveniently used to evaluate the growth parameters and in this way the intrinsic growth behavior of a bacterial species growing in heterogeneous phases can be estimated. In addition, a new method has been proposed, in this case, the lag period and the double time for a bacterial population can also be reasonably evaluated. This approach proposed could thus be expected to reveal important insight of bacterial population growth. Some aspects in modeling population growth are also discussed.

  1. Effect of the population heterogeneity on growth behavior and its estimation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Different types of the Logistic model are constructed based on a simple assumption that the microbial populations are all composed of homogeneous members and consequently, the condition of design for the initial value of these models has to be rather limited in the case of N(t0)=N0. Therefore, these models cannot distinguish the dynamic behavior of the populations possessing the same N0 from heteroge-neous phases. In fact, only a certain ratio of the cells in a population is dividing at any moment during growth progress, termed as θ, and thus, ddNt not only depends on N, but also on θ. So θ is a necessary element for the condition design of the initial value. Unfortunately, this idea has long been neglected in widely used growth models. However, combining together the two factors (N0 and θ ) into the initial value often leads to the complexity in the mathematical solution. This difficulty can be overcome by using instantaneous rates (Vinst) to express growth progress. Previous studies in our laboratory sug-gested that the Vinst curve of the bacterial populations all showed a Guassian function shape and thus, the different growth phases can be reasonably distinguished. In the present study, the Gaussian dis-tribution function was transformed approximately into an analytical form (0.5x ibxYi αe=20) that can be conveniently used to evaluate the growth parameters and in this way the intrinsic growth behavior of a bacterial species growing in heterogeneous phases can be estimated. In addition, a new method has been proposed, in this case, the lag period and the double time for a bacterial population can also be reasonably evaluated. This approach proposed could thus be expected to reveal important insight of bacterial population growth. Some aspects in modeling population growth are also discussed.

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

    Science.gov (United States)

    Jianwei Zhang; Bert M. Cregg

    2005-01-01

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

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

    NARCIS (Netherlands)

    C.A.M. de Meijer (Claudine)

    2012-01-01

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

  4. Genomic sharing surrounding alleles identical by descent : Effects of genetic drift and population growth

    NARCIS (Netherlands)

    te Meerman, G J; Van der Meulen, M A

    1997-01-01

    The number of identical deleterious mutations present in a population may become very large, depending on the combined effect of genetic drift, population growth and limited negative selection. The distribution of the length of the shared area between two random chromosomes carrying the mutations ha

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

    DEFF Research Database (Denmark)

    Steiner, Uli; Tuljapurkar, Shripad; Coulson, Tim

    2014-01-01

    to age-structured populations. Here we generalize this result to populations structured by stage and age by providing a new, unique measure of reproductive timing (Tc) that, along with net reproductive rate (R0), has a direct mathematical relationship to and approximates growth rate (r). We use simple...

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

    NARCIS (Netherlands)

    C.A.M. de Meijer (Claudine)

    2012-01-01

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

  7. Genomic sharing surrounding alleles identical by descent : Effects of genetic drift and population growth

    NARCIS (Netherlands)

    te Meerman, G J; Meulen ,van der Martin

    1997-01-01

    The number of identical deleterious mutations present in a population may become very large, depending on the combined effect of genetic drift, population growth and limited negative selection. The distribution of the length of the shared area between two random chromosomes carrying the mutations ha

  8. Age and growth in three populations of Dosinia exoleta (Bivalvia: Veneridae) from the Portuguese coast

    Science.gov (United States)

    Moura, Paula; Vasconcelos, Paulo; Gaspar, Miguel B.

    2013-12-01

    The present study aimed at estimating the age and growth in three populations of Dosinia exoleta from the Portuguese coast (Aveiro in the north, Setúbal in the southwest and Faro in the south). Two techniques were compared to ascertain the most suitable method for ageing D. exoleta. Growth marks on the shell surface and acetate peel replicas of sectioned shells were the techniques applied. Two hypotheses were tested: growth parameters present latitudinal variation along the Portuguese coast; growth parameters are influenced by the fishing exploitation. Shell surface rings proved inappropriate for ageing this species, whereas acetate peels provided realistic estimates of the von Bertalanffy growth parameters ( K, L ∞ and t 0). A latitudinal gradient in growth rate was detected, with a clear southward increase in the growth coefficient ( K) of D. exoleta (Faro > Setúbal and Aveiro) indicating that warmer waters in southern Portugal provide optimal conditions for the growth of this species. Fishing exploitation in northern Portugal targets larger individuals and leaves behind a younger population of smaller individuals, decreasing the asymptotic shell length ( L ∞ ) of D. exoleta from Aveiro. The overall growth performance was compared among populations of D. exoleta and with other venerid species worldwide.

  9. Quantitative traits correlative analysis and growth comparison among different populations of bay scallop,Argopecten irradians

    Institute of Scientific and Technical Information of China (English)

    LIUBaozhong; LIANGYubo; LIUXiaolin; DONGBo; XIANGJianhai

    2004-01-01

    The shell traits and weight traits are measured in cultured populations of bay scallop, Argopecten irradians. The results of regression analysis show that the regression relationships for all the traits are significant (P0.05). The multiple regression equation is obtained to estimate live body weight and tissue weight. The above traits except anterior and posterior auricle length are used for the growth and production comparison among three cultured populations, Duncan's new multiple range procedure analysis shows that all the traits in the Lingshuiqiao (LSQ) population are much more significant than those of the other two populations (P0.05). The results indicate that the LSQ population has a higher growth rate and is expected to be more productive than the other two populations.

  10. Application of High Resolution Satellite Imagery to Characterize Individual-Based Environmental Heterogeneity in a Wild Blue Tit Population

    Directory of Open Access Journals (Sweden)

    Marta Szulkin

    2015-10-01

    Full Text Available Environmental heterogeneity in space and time plays a key role in influencing trait variability in animals, and can be particularly relevant to animal phenology. Until recently, the use of remotely sensed imagery in understanding animal variation was limited to analyses at the population level, largely because of a lack of high-resolution data that would allow inference at the individual level. We evaluated the potential of SPOT 4 (Take 5 satellite imagery data (with observations every fifth day at 20 m resolution and equivalent to acquisition parameters of Sentinel-2 in animal ecology research. We focused on blue tit Cyanistes caeruleus reproduction in a study site containing 227 nestboxes scattered in a Mediterranean forest dominated by deciduous downy oaks Quercus pubescens with a secondary cover of evergreen holm oaks Quercus ilex. We observed high congruence between ground data collected in a 50 m radius around each nestbox and NDVI values averaged across a 5 by 5 pixel grid centered around each nestbox of the study site. The number of deciduous and evergreen oaks around nestboxes explained up to 66% of variance in nestbox-centered, SPOT-derived NDVI values. We also found highly equivalent patterns of spatial autocorrelation for both ground- and satellite-derived indexes of environmental heterogeneity. For deciduous and evergreen oaks, the derived NDVI signal was highly distinctive in winter and early spring. June NDVI values for deciduous and evergreen oaks were higher by 58% and 8% relative to February values, respectively. The number of evergreen oaks was positively associated with later timing of breeding in blue tits. SPOT-derived, Sentinel-2 like imagery thus provided highly reliable, ground-validated information on habitat heterogeneity of direct relevance to a long-term field study of a free-living passerine bird. Given that the logistical demands of gathering ground data often limit our understanding of variation in animal

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-22

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

  12. [Population growth in Plasencia in the nineteenth century].

    Science.gov (United States)

    Sanchez De La Calle, J A

    1993-01-01

    "Using sources such as parish registers, civil registers, records of the town hall, inquiries, [censuses] and list of inhabitants, we have been able to confirm the existence of four different stages in the demographic development of Plasencia [Spain]. The first one, between 1800 and 1815, is characterized by a scarce growing.... The second one, between 1816 and 1839, shows a certain increase which is restrained at the end of the 30s because of some epidemic illness (cholera and various fevers). The period between 1840 and 1871 is a stage of slow growing due to many subsistence crises. The fourth stage, 1872-1899, continues the same outline with a great rising of mortality, which does not prevent the rising of population in Plasencia caused by a high rate of inmigration." (SUMMARY IN ENG AND FRE)

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

    Directory of Open Access Journals (Sweden)

    Xavier Franch Auladell

    2013-01-01

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

  14. The effects of economic and population growth on national saving and inequality.

    Science.gov (United States)

    Deaton, A S; Paxson, C H

    1997-02-01

    This is a progress report on ongoing research into the effects of economic and population growth on national saving rates and inequality. The theoretical basis for the investigation is the life cycle model of saving and inequality. We report evidence that is conditional on the validity of the model, as well as evidence that casts doubt on it. Using time series of cross-sectional household surveys from Taiwan, Thailand, Britain, and the United States, we show that it is possible to force a life cycle interpretation on the data on consumption, income, and saving, but that the evidence is not consistent with large rate-of-growth effects, whereby economic and population growth enhances rates of national saving. The well-established cross-country link between economic growth and saving cannot be attributed to life cycle saving, nor will changes in economic or population growth exert large effects on saving within individual countries. There is evidence in favor of the life cycle model's prediction that within-cohort inequality of consumption and of total income--though not necessarily inequality of earnings--should increase with the age of the cohort. Decreases in the population growth rate redistribute population toward older, more unequal, cohorts, and can increase national inequality. We provide calculations on the magnitude of these effects.

  15. Sedimentary iron inputs stimulate seagrass ( Posidonia oceanica) population growth in carbonate sediments

    Science.gov (United States)

    Marbà, Núria; Duarte, Carlos M.; Holmer, Marianne; Calleja, Maria Ll.; Álvarez, Elvira; Díaz-Almela, Elena; Garcias-Bonet, Neus

    2008-02-01

    The relationship between sedimentary Fe inputs and net seagrass population growth across a range of Posidonia oceanica meadows growing in carbonate Mediterranean sediments (Balearic Islands, Spain; SE Iberian Peninsula, Spain; Limassol, Cyprus; Sounion, Greece) was examined using comparative analysis. Sedimentary Fe inputs were measured using benthic sediment traps and the net population growth of P. oceanica meadows was assessed using direct census of tagged plants. The meadows examined ranged from meadows undergoing a severe decline to expanding meadows (specific net population growth, from -0.14 yr -1 to 0.05 yr -1). Similarly, Fe inputs to the meadows ranged almost an order of magnitude across meadows (8.6-69.1 mg Fe m -2 d -1). There was a significant, positive relationship between sedimentary iron inputs and seagrass net population growth, accounting for 36% of the variability in population growth across meadows. The relationship obtained suggested that seagrass meadows receiving Fe inputs below 43 mg Fe m -2 d -1 are vulnerable and in risk of decline, confirming the pivotal role of Fe in the control of growth and the stability of seagrass meadows in carbonate sediments.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Peter M. Allen

    1999-01-01

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

  18. Dwarf spheroidal satellites of M31: I. Variable stars and stellar populations in Andromeda XIX

    CERN Document Server

    Cusano, Felice; Garofalo, Alessia; Cignoni, Michele; Federici, Luciana; Marconi, Marcella; Musella, Ilaria; Ripepi, Vincenzo; Boutsia, Konstantina; Fumana, Marco; Gallozzi, Stefano; Testa, Vincenzo

    2013-01-01

    We present B,V time-series photometry of Andromeda XIX (And XIX), the most extended (half-light radius of 6.2') of Andromeda's dwarf spheroidal companions, that we observed with the Large Binocular Cameras at the Large Binocular Telescope. We surveyed a 23'x 23' area centered on And XIX and present the deepest color magnitude diagram (CMD) ever obtained for this galaxy, reaching, at V~26.3 mag, about one magnitude below the horizontal branch (HB). The CMD shows a prominent and slightly widened red giant branch, along with a predominantly red HB, which, however, extends to the blue to significantly populate the classical instability strip. We have identified 39 pulsating variable stars, of which 31 are of RR Lyrae type and 8 are Anomalous Cepheids (ACs). Twelve of the RR Lyrae variables and 3 of the ACs are located within And XIX's half light radius. The average period of the fundamental mode RR Lyrae stars ( = 0.62 d, \\sigma= 0.03 d) and the period-amplitude diagram qualify And XIX as an Oosterhoff-Intermedia...

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

    Directory of Open Access Journals (Sweden)

    John P DeLong

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

  20. Dwarf spheroidal satellites of M31. I. Variable stars and stellar populations in Andromeda XIX

    Energy Technology Data Exchange (ETDEWEB)

    Cusano, Felice; Clementini, Gisella; Garofalo, Alessia; Federici, Luciana, E-mail: felice.cusano@oabo.inaf.it, E-mail: gisella.clementini@oabo.inaf.it, E-mail: luciana.federici@oabo.inaf.it, E-mail: alessia.garofalo@studio.unibo.it [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); and others

    2013-12-10

    We present B, V time-series photometry of Andromeda XIX (And XIX), the most extended (half-light radius of 6.'2) of Andromeda's dwarf spheroidal companions, which we observed with the Large Binocular Cameras at the Large Binocular Telescope. We surveyed a 23' × 23' area centered on And XIX and present the deepest color-magnitude diagram (CMD) ever obtained for this galaxy, reaching, at V ∼ 26.3 mag, about one magnitude below the horizontal branch (HB). The CMD shows a prominent and slightly widened red giant branch, along with a predominantly red HB, which extends to the blue to significantly populate the classical instability strip. We have identified 39 pulsating variable stars, of which 31 are of RR Lyrae type and 8 are Anomalous Cepheids (ACs). Twelve of the RR Lyrae variables and three of the ACs are located within And XIX's half light radius. The average period of the fundamental mode RR Lyrae stars ((P {sub ab}) = 0.62 days, σ = 0.03 days) and the period-amplitude diagram qualify And XIX as an Oosterhoff-Intermediate system. From the average luminosity of the RR Lyrae stars ((V(RR)) = 25.34 mag, σ = 0.10 mag), we determine a distance modulus of (m – M){sub 0} = 24.52 ± 0.23 mag in a scale where the distance to the Large Magellanic Cloud (LMC) is 18.5 ± 0.1 mag. The ACs follow a well-defined Period-Wesenheit (PW) relation that appears to be in very good agreement with the PW relationship defined by the ACs in the LMC.

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

    Science.gov (United States)

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

    2012-11-01

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

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

    Science.gov (United States)

    Xu, D

    1983-01-01

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

  3. Getting the timing right: antler growth phenology and sexual selection in a wild red deer population.

    Science.gov (United States)

    Clements, Michelle N; Clutton-Brock, Tim H; Albon, Steve D; Pemberton, Josephine M; Kruuk, Loeske E B

    2010-10-01

    There has been growing interest in the determinants of the annual timing of biological phenomena, or phenology, in wild populations, but research on vertebrate taxa has primarily focused on the phenology of reproduction. We present here analyses of the phenology of the annual growth of a secondary sexual characteristic, antlers in red deer (Cervus elaphus) males. The long-term individual-based data from a wild population of red deer on the Isle of Rum, Scotland allow us to consider ecological factors influencing variation in the phenology of growth of antlers, and the implications of variation in antler growth phenology with respect to the phenotype of antler grown (antler mass) and annual breeding success. The phenology of antler growth was influenced by local environmental conditions: higher population density delayed both the start date (during spring) and the relative end date (in late summer) of antler growth, and warmer temperatures in the September and April prior to growth advanced start and end dates, respectively. Furthermore, there was variation between individuals in this phenotypic plasticity of start date, although not in that of end date of growth. The phenology of antler growth impacted on the morphology of antlers grown, with individuals who started and ended growth earliest having the heaviest antlers. The timing of antler growth phenology was associated with breeding success in the following mating season, independently of the mass of antlers grown: an earlier start of antler growth was associated with siring a higher number of the calves born the following spring. Our results suggest that the phenology of traits that are not directly correlated with offspring survival may also regularly show correlations with fitness.

  4. Modeling circadian clock-cell cycle interaction effects on cell population growth rates.

    Science.gov (United States)

    El Cheikh, R; Bernard, S; El Khatib, N

    2014-12-21

    The circadian clock and the cell cycle are two tightly coupled oscillators. Recent analytical studies have shown counter-intuitive effects of circadian gating of the cell cycle on growth rates of proliferating cells which cannot be explained by a molecular model or a population model alone. In this work, we present a combined molecular-population model that studies how coupling the circadian clock to the cell cycle, through the protein WEE1, affects a proliferating cell population. We show that the cell cycle can entrain to the circadian clock with different rational period ratios and characterize multiple domains of entrainment. We show that coupling increases the growth rate for autonomous periods of the cell cycle around 24 h and above 48 h. We study the effect of mutation of circadian genes on the growth rate of cells and show that disruption of the circadian clock can lead to abnormal proliferation. Particularly, we show that Cry 1, Cry 2 mutations decrease the growth rate of cells, Per 2 mutation enhances it and Bmal 1 knockout increases it for autonomous periods of the cell cycle less than 21 h and decreases it elsewhere. Combining a molecular model to a population model offers new insight on the influence of the circadian clock on the growth of a cell population. This can help chronotherapy which takes benefits of physiological rhythms to improve anti-cancer efficacy and tolerance to drugs by administering treatments at a specific time of the day.

  5. Population growth of carmine cochineal in giant cactus pear artificially infested on laboratory conditions

    Directory of Open Access Journals (Sweden)

    Jacinto de Luna Batista

    2009-12-01

    Full Text Available The carmine cochineal (Dactylopius opuntiae is up today, the main pest of the giant cactus pear in the states of Pernambuco, Paraíba and Ceará. This research aimed to measure the population growth of D. opuntiae in cladodes of giant cactus pear infested in the laboratory conditios. Cladodes of giant cactus pear were artificially infested with colonies carmine cochineal. The experiment was initiated on 10/02/2009 and ended 10/03/2009. Shaped population growth is a function of time and infestation levels of initial and final, using a regression analysis with the application ASSISTAT 8.0 Beta. Data were also submitted to analysis of variance - ANOVA using a completely randomized design (CRD with eight treatments and five replications. The comparison of means was done by Tukey test at 5% probability. The results of the regression equations and curves showed that the insect Dactylopius opuntiae had a population growth in geometric progression in all treatments. Treatment eight colonies had the largest population growth where the average was obtained 1223.80 colonies / cladodes in 35 days. The lack of sunshine, average temperature of 22 º C and relative humidity of 75% RH during the study period, particularly favored the growth of the insect population.

  6. Inference of Super-exponential Human Population Growth via Efficient Computation of the Site Frequency Spectrum for Generalized Models

    OpenAIRE

    Gao, Feng; Keinan, Alon

    2015-01-01

    The site frequency spectrum (SFS) and other genetic summary statistics are at the heart of many population genetic studies. Previous studies have shown that human populations have undergone a recent epoch of fast growth in effective population size. These studies assumed that growth is exponential, and the ensuing models leave an excess amount of extremely rare variants. This suggests that human populations might have experienced a recent growth with speed faster than exponential. Recent stud...

  7. Plant defences limit herbivore population growth by changing predator-prey interactions.

    Science.gov (United States)

    Kersch-Becker, Mônica F; Kessler, André; Thaler, Jennifer S

    2017-09-13

    Plant quality and predators are important factors affecting herbivore population growth, but how they interact to regulate herbivore populations is not well understood. We manipulated jasmonate-induced plant resistance, exposure to the natural predator community and herbivore density to test how these factors jointly and independently affect herbivore population growth. On low-resistance plants, the predator community was diverse and abundant, promoting high predator consumption rates. On high-resistance plants, the predator community was less diverse and abundant, resulting in low predator consumption rate. Plant resistance only directly regulated aphid population growth on predator-excluded plants. When predators were present, plant resistance indirectly regulated herbivore population growth by changing the impact of predators on the herbivorous prey. A possible mechanism for the interaction between plant resistance and predation is that methyl salicylate, a herbivore-induced plant volatile attractive to predators, was more strongly induced in low-resistance plants. Increased plant resistance reduced predator attractant lures, preventing predators from locating their prey. Low-resistance plants may regulate herbivore populations via predators by providing reliable information on prey availability and increasing the effectiveness of predators. © 2017 The Author(s).

  8. Population Growth, Socio-economy and Quality of life in Birbhum District, West Bengal, India

    Directory of Open Access Journals (Sweden)

    Piyal Basu Roy

    2011-09-01

    Full Text Available The present study attempts to analyze the decadal variation of population growth, socio-economic condition and quality of life of the people in Birbhum District, West Bengal, India. It has been well accepted that if the amount of resource available within a country does not feed its total inhabitants due to excessive population in comparison to existing resource, quality of life of individual and socio-economy of that area collapse, which is very often found in developing nations of the world. Consequently, well being of common people through provision of basic needs like food, clothing, shelter, education, and health is obstructed. This adversely affects the quality of life of an individual. Increasing rate of population growth brings reduction in per capita income of people by creating pressure on land, making consumer product costlier and decreasing national capital. Moreover, the increase in the population growth rate due to high fertility, low mortality and inflow of migrants prevent improved quality of life also. Among others factors influencing Quality of Life (QOL in particular and socio-economic development and human well being in general are literacy, dietary pattern, transportation, and health service etc., the assessment of which reveals that study area turns out to be one of the backward districts of West Bengal where socio-economy and quality of life are of unfortunate character due to excessive population growth and inconsistent infrastructural development that cannot keep pace with the population increase.

  9. Age, growth and mortality in four populations of the boring bivalve Lithophaga patagonica from Argentina

    Science.gov (United States)

    Bagur, María; Richardson, Christopher A.; Gutiérrez, Jorge L.; Arribas, Lorena P.; Doldan, M. Socorro; Palomo, M. Gabriela

    2013-08-01

    The boring bivalve Lithophaga patagonica (d'Orbigny, 1842) is a locally abundant inhabitant of hard substrata in the coastal waters of the Southwestern Atlantic. In this paper, we describe the growth, age and mortality of three intertidal rock-boring populations of L. patagonica and one subtidal oyster shell (Ostrea puelchana) boring population. An analysis of acetate peel replicas of shell sections showed that L. patagonica slows down its growth during autumn-winter, which leads to changes in the direction and rate of shell deposition and the formation of conspicuous annual (low temperature induced) clefts in the shell margin. Cleft counts and Von Bertalanffy growth analyses indicated that maximum age varies from 4 years in the oyster-boring population to 13 years in a rock-boring one (longevity estimates varied between 6.5 and 15 years, respectively). Maximum asymptotic length (L∞) and Von Bertalanffy growth constant (K) were also variable between populations (L∞ between 14.76 and 36.95 mm and K from 0.20 to 0.90 yr- 1 respectively). Mortality rates were higher at the two southernmost populations. Type (rock vs. oyster), composition and hardness of the substrata are likely the main factors controlling the observed differences between populations.

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

    Science.gov (United States)

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

    2009-07-01

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

  11. Survival, Recruitment, and Population Growth Rate of an Important Mesopredator: The Northern Raccoon

    Science.gov (United States)

    Troyer, Elizabeth M.; Cameron Devitt, Susan E.; Sunquist, Melvin E.; Goswami, Varun R.; Oli, Madan K.

    2014-01-01

    Populations of mesopredators (mid-sized mammalian carnivores) are expanding in size and range amid declining apex predator populations and ever-growing human presence, leading to significant ecological impacts. Despite their obvious importance, population dynamics have scarcely been studied for most mesopredator species. Information on basic population parameters and processes under a range of conditions is necessary for managing these species. Here we investigate survival, recruitment, and population growth rate of a widely distributed and abundant mesopredator, the northern raccoon (Procyon lotor), using Pradel’s temporal symmetry models and >6 years of monthly capture-mark-recapture data collected in a protected area. Monthly apparent survival probability was higher for females (0.949, 95% CI = 0.936–0.960) than for males (0.908, 95% CI = 0.893–0.920), while monthly recruitment rate was higher for males (0.091, 95% CI = 0.078–0.106) than for females (0.054, 95% CI = 0.042–0.067). Finally, monthly realized population growth rate was 1.000 (95% CI = 0.996–1.004), indicating that our study population has reached a stable equilibrium in this relatively undisturbed habitat. There was little evidence for substantial temporal variation in population growth rate or its components. Our study is one of the first to quantify survival, recruitment, and realized population growth rate of raccoons using long-term data and rigorous statistical models. PMID:24901349

  12. Living bacteria rheology: population growth, aggregation patterns and cooperative behaviour under different shear flows

    CERN Document Server

    Patricio, P; Portela, R; Sobral, R G; Grilo, I R; Cidade, T; Leal, C R

    2014-01-01

    The activity of growing living bacteria was investigated using real-time and in situ rheology -- in stationary and oscillatory shear. Two different strains of the human pathogen Staphylococcus aureus -- strain COL and its isogenic cell wall autolysis mutant -- were considered in this work. For low bacteria density, strain COL forms small clusters, while the mutant, presenting deficient cell separation, forms irregular larger aggregates. In the early stages of growth, when subjected to a stationary shear, the viscosity of both strains increases with the population of cells. As the bacteria reach the exponential phase of growth, the viscosity of the two strains follow different and rich behaviours, with no counterpart in the optical density or in the population's colony forming units measurements. While the viscosity of strain COL keeps increasing during the exponential phase and returns close to its initial value for the late phase of growth, where the population stabilizes, the viscosity of the mutant strain ...

  13. Effects of fertilizers on soil’s microbial growth and populations: a review

    Directory of Open Access Journals (Sweden)

    Ojo OI

    2015-07-01

    Full Text Available Soil nutrients availability and decomposition of organic matter depends on microorganism but there are little available literatures on the possible effects of nutrients fixing chemicals and substances on the survival and population distribution of various microbes. Also, because of importance of organic and inorganic fertilizers to increase the soil microorganisms needed for the growth of plants there is need for comprehensive review of existing literature on the subject. This paper reviewed the effects of fertilizers on soil’s microbial growth and populations in available literatures. Various studies agreed that low microbe population due to lack of organic matter can be easily rectified by amending the soil with fertilizers and organic matter and allowing time for microbial growth therefore jump-starting the reproduction of microbes by adding beneficial microbes along with organic matter. Microbe improves soil structure by the humus they create while digesting organic matter and also help in nitrogen fixing.

  14. Influence of plant population and nitrogen-fertilizer at various levels on growth and growth efficiency of maize.

    Science.gov (United States)

    Tajul, M I; Alam, M M; Hossain, S M M; Naher, K; Rafii, M Y; Latif, M A

    2013-01-01

    Field experiments were conducted to evaluate plant population and N-fertilizer effects on yield and yield components of maize (Zea mays L.). Three levels of plant populations (53000, 66000, and 800,000 plants ha⁻¹ corresponding to spacings of 75 × 25, 60 × 25, and 50 × 25 cm) and 4 doses of N (100, 140, 180, and 220 kg ha⁻¹) were the treatment variables. Results revealed that plant growth, light interception (LI), yield attributes, and grain yield varied significantly due to the variations in population density and N-rates. Crop growth rate (CGR) was the highest with the population of 80,000 ha⁻¹ receiving 220 kg N ha⁻¹, while relative growth rate (RGR) showed an opposite trend of CGR. Light absorption was maximum when most of densely populated plant received the highest amount of N (220 kg N ha⁻¹). Response of soil-plant-analysis development (SPAD) value as well as N-content to N-rates was found significant. Plant height was the maximum at the lowest plant density with the highest amount of N. Plants that received 180 kg N ha⁻¹ with 80,000 plants ha⁻¹ had larger foliage, greater SPAD value, and higher amount of grains cob⁻¹ that contributed to the maximum yield (5.03 t ha⁻¹) and the maximum harvest index (HI) compared to the plants in other treatments.

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

    Directory of Open Access Journals (Sweden)

    M. I. Tajul

    2013-01-01

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

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

    Science.gov (United States)

    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.

  17. Existence of limit cycles in the Solow model with delayed-logistic population growth.

    Science.gov (United States)

    Bianca, Carlo; Guerrini, Luca

    2014-01-01

    This paper is devoted to the existence and stability analysis of limit cycles in a delayed mathematical model for the economy growth. Specifically the Solow model is further improved by inserting the time delay into the logistic population growth rate. Moreover, by choosing the time delay as a bifurcation parameter, we prove that the system loses its stability and a Hopf bifurcation occurs when time delay passes through critical values. Finally, numerical simulations are carried out for supporting the analytical results.

  18. Black Populations and Economic Growth: An Extreme Bounds Analysis of Mississippi County-Level Data

    OpenAIRE

    Young, Andrew; Higgins, Matthew; Levy, Daniel

    2007-01-01

    We use Mississippi county-level data on (per capita) income and the percentages of populations that are Black (henceforth "Black") to examine the relationship between race and economic growth. The analysis is also conditioned on 40 other economic and socio-demographic variables. Given a negative and statistically significant partial correlation between income growth and Black, we ask if it is robust to exhaustive combinations of other conditioning variables (taken 3 at a time). The evidence ...

  19. Population Ageing, Government Budgets, and Productivity Growth in Politico-Economic Equilibrium

    OpenAIRE

    Gonzales-Eiras, Martín; Niepelt, Dirk

    2007-01-01

    We analyze the effect of changes in fertility and longevity on taxes, the composition of government spending, and productivity. To that purpose, we introduce politics in an OLG economy with endogenous growth due to human and physical capital accumulation. Population ageing shifts political power from students and workers to retirees, leading to a reallocation of resources from education spending to retirement benefits and a slowdown of productivity growth. Calibrated to U.S. data, the closed-...

  20. Testosterone inhibits transforming growth factor-β signaling during myogenic differentiation and proliferation of mouse satellite cells: potential role of follistatin in mediating testosterone action.

    Science.gov (United States)

    Braga, Melissa; Bhasin, Shalender; Jasuja, Ravi; Pervin, Shehla; Singh, Rajan

    2012-03-05

    Testosterone (T) administration is associated with increased satellite cell number and skeletal muscle hypertrophy, although there is considerable heterogeneity in the response of different skeletal muscle groups to T in vivo. We investigated the effects of T on the growth and differentiation of satellite cells isolated from levator ani (LA) and gastrocnemius (gastroc) muscles. T up regulated follistatin (Fst) expression, but down regulated the mRNA and protein expression of a number of genes in the transforming growth factor-beta (TGF-β)-signaling pathway. Inhibition of Fst expression by small interfering RNA (siRNA) inhibited myogenic differentiation and blocked the pro-myogenic effects of T. Treatment of satellite cells with T or Fst up regulated the expression of Pax7 and PCNA, and increased their proliferation. T and Fst blocked TGF-β induced inhibition of growth and myogenic differentiation and down regulated TGF-β-dependent transcriptome in both LA and gastroc cells. We conclude that T stimulation of satellite cell proliferation and myogenic differentiation are associated with up regulation of Fst and inhibition of TGF-β-signaling.

  1. Vascular Endothelial Growth Factor-A Is Associated with Chronic Mountain Sickness in the Andean Population

    OpenAIRE

    Espinoza, Jose R.; Alvarez, Giancarlo; León-Velarde, Fabiola; Ju Preciado, Hugo F.; Macarlupu, Jose-Luis; Rivera-Ch, Maria; Rodriguez, Jorge; Favier, Judith; Gimenez-Roqueplo, Anne-Paule; Richalet, Jean-Paul

    2014-01-01

    Espinoza, Jose R., Giancarlo Alvarez, Fabiola León-Velarde, Hugo F. Ju Preciado, Jose-Luis Macarlupu, Maria Rivera-Ch, Jorge Rodriguez, Judith Favier, Anne-Paule Gimenez-Roqueplo, and Jean-Paul Richalet. Vascular endothelial growth factor-A is associated with chronic mountain sickness in Andean population. High Alt Med Biol. 15:146–154, 2014.—A study of chronic mountain sickness (CMS) with a candidate gene—vascular endothelial growth factor A (VEGFA)—was carried out in a Peruvian population l...

  2. Population growth of carmine cochineal in giant cactus pear artificially infested on laboratory conditions

    OpenAIRE

    2009-01-01

    The carmine cochineal (Dactylopius opuntiae) is up today, the main pest of the giant cactus pear in the states of Pernambuco, Paraíba and Ceará. This research aimed to measure the population growth of D. opuntiae in cladodes of giant cactus pear infested in the laboratory conditios. Cladodes of giant cactus pear were artificially infested with colonies carmine cochineal. The experiment was initiated on 10/02/2009 and ended 10/03/2009. Shaped population growth is a function of time and infesta...

  3. Spatial and temporal changes in household structure locations using high-resolution satellite imagery for population assessment: an analysis in southern Zambia, 2006-2011

    Directory of Open Access Journals (Sweden)

    Timothy Shields

    2016-05-01

    Full Text Available Satellite imagery is increasingly available at high spatial resolution and can be used for various purposes in public health research and programme implementation. Comparing a census generated from two satellite images of the same region in rural southern Zambia obtained four and a half years apart identified patterns of household locations and change over time. The length of time that a satellite image-based census is accurate determines its utility. Households were enumerated manually from satellite images obtained in 2006 and 2011 of the same area. Spatial statistics were used to describe clustering, cluster detection, and spatial variation in the location of households. A total of 3821 household locations were enumerated in 2006 and 4256 in 2011, a net change of 435 houses (11.4% increase. Comparison of the images indicated that 971 (25.4% structures were added and 536 (14.0% removed. Further analysis suggested similar household clustering in the two images and no substantial difference in concentration of households across the study area. Cluster detection analysis identified a small area where significantly more household structures were removed than expected; however, the amount of change was of limited practical significance. These findings suggest that random sampling of households for study participation would not induce geographic bias if based on a 4.5-year-old image in this region. Application of spatial statistical methods provides insights into the population distribution changes between two time periods and can be helpful in assessing the accuracy of satellite imagery.

  4. Effect of linear alkylbenzene sulfonate on population growth of Daphnia galeata: a life table evaluation.

    Science.gov (United States)

    Tanaka, Y; Nakanishi, J

    2001-01-01

    The chronic effect of linear alkylbenzene sulfonate (LAS12) on a daphnid species (Daphnia galeata) was examined by the life table experiment. The estimated responses in the intrinsic rate of population growth r were analyzed with two alternate concentration-response functions, i.e., the power function and the quadratic function. Based on the best-fit power function model with biases corrected by the jackknife procedure, the population-level EC50, which is defined as the concentration of chemicals that reduces the population growth rate (the intrinsic rate of natural increase) by 50%, was estimated as 2.5 mg/L. The 48-h acute immobility test yielded EC50 of 4.6 mg/L. The population-level effect of LAS12 on this test species is considerably more sensitive than the acute lethal effects to neonates.

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

    Science.gov (United States)

    Stutz, Aaron Jonas

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Aaron Jonas Stutz

    Full Text Available 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

  7. Taiyuan Satellite Launch Center

    Institute of Scientific and Technical Information of China (English)

    LiuJie

    2004-01-01

    There are three major space launch bases in China, the Jiuquan Satellite Launch Center,the Taiyuan Satellite Launch Center and the Xichang Satellite Launch Center. All the three launch centers are located in sparsely populated areas where the terrain is even and the field of vision is broad. Security, transport conditions and the influence of the axial rotation

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2003-01-01

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

  10. Effects of temperature and population density on von Bertalanffy growth parameters in Atlantic herring: a macro-ecological analysis

    NARCIS (Netherlands)

    Brunel, T.P.A.; Dickey-Collas, M.

    2010-01-01

    The effect of temperature and population density on the growth of Atlantic herring Clupea harengus was studied using a comparative approach applied to 15 North Atlantic populations. The von Bertalanffy (VB) equation was applied to describe mean growth of individuals in each population, both averaged

  11. Behavioural models of population growth rates: implications for conservation and prediction.

    OpenAIRE

    Sutherland, William J.; Norris, Ken

    2002-01-01

    Conservation biologists often wish to predict how vertebrate populations will respond to local or global changes in conditions such as those resulting from sea-level rise, deforestation, exploitation, genetically modified crops, global warming, human disturbance or from conservation activities. Predicting the consequences of such changes almost always requires understanding the population growth rate and the density dependence. Traditional means of directly measuring density dependence are of...

  12. Birth, growth and death as structuring tools in bacterial population dynamics

    OpenAIRE

    Lavric, Vasile; Graham, David W.

    2010-01-01

    Abstract A new model is presented that describes microbial population dynamics that emerge from complex interactions among birth, growth and death as oriented, discrete events. Specifically, birth and death act as structuring operators for individual organisms within the population, which become synchronised as age clusters (called cell-generations that are structured in age-classes) that are born at the same time and die in concert; a pattern very consistent with recent experiment...

  13. Demographic Stress and Governance: The Influence of Nigerian Population Growth on the Risk of Civil Conflict

    Science.gov (United States)

    2015-06-01

    growth is declining , the United Nations projects world population to reach a staggering 9.6 billion by 2050. In that time, Nigeria is expected to...children according to a given fertility rate. Rates above two indicate growing populations with declining median ages.11 The following chart...and popular disorders, as merchants, shopkeepers, and craftsmen forcibly wrested control of London from the aldermen, as crowds in the city

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

    Science.gov (United States)

    Mahar, Dennis J., Ed.; And Others

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

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

    Science.gov (United States)

    Mech, L. David; Fieberg, John

    2015-01-01

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

  16. Population Growth of Small Harmful Rats in Grassland Subjected to Noise

    Institute of Scientific and Technical Information of China (English)

    LIU Xue-Mei; LI Zhi-Bing; XIE Hui-Zhang; AI Bao-Quan; CHENG Xiao-Bo; LIU Liang-Gang

    2007-01-01

    The population growth of small harmful rats in grassland subjected to environment fluctuation has been modelled in a logistic equation. Two correlated random variables responsible to the fluctuation of the genetic factor and the suppression factor are used. A two-peak structure of the steady probability distribution of rate population is observed in the large fluctuation regime of the genetic factor. With the increase of correlation constant λ, the steady probability distribution can change from two peaks to a single peak. The suppression factor i and its fluctuation also affect the steady probability distribution and can push it toward a small population.

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

    Science.gov (United States)

    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…

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

    NARCIS (Netherlands)

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

    2007-01-01

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

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

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

    2016-12-13

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

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

    NARCIS (Netherlands)

    Dagnelie, P.C.

    1988-01-01

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

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

    Science.gov (United States)

    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.)

  3. Effect of dispersants on the growth of indigenous bacterial population and biodegradation of crude oil

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Row, A.

    of the dispersants were toxic, except IB 2/80, to the bacterial population. All of the dispersants, when used alone, or in combination with the crude oil, supported good growth of bacteria. The Saudi Arabian crude oil by itself was toxic to the bacteria, and when...

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

    DEFF Research Database (Denmark)

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

    1997-01-01

    Carlo method is shown to be superior with respect to versatility. With measurements of 100 hyphal elements to represent a steady state and using the Monte Carlo method and a statistical test it is shown that one can discriminate between four models of hyphal fragmentation in submerged cultures. (C) 1997......Descriptions of population dynamics in submerged cultures are important when studying the mechanisms of growth and fragmentation of filamentous microorganisms. Population models are traditionally formulated as population balance equations. Population models of filamentous morphology are difficult...... to solve because of random fragmentation, which introduces an integral term into the population balance equations. Balances for the systemic properties, e.g. concentration of hyphal elements, substrate concentration, average total hyphal length, and average number of growing tips, are set up. Based...

  5. [The growth and distribution of the population of Brazil: recent trends].

    Science.gov (United States)

    Martine, G; Camargo, L

    1984-01-01

    Population trends underwent profound changes in Brazil during the last few decades. An important decrease in the rate of population growth was registered in the 1970s. This decrease is attributable to a decline in the level of fertility, which was observed in all regions and in both urban and rural areas. In order to explain this decline, it is necessary to analyze both structural and circumstantial factors related to the political, economic, and social context of the times. Main trends in population redistribution during the 1970s can be regrouped in terms of interregional exchanges and rural-urban migration. A growing convergence between these 2 types of patterns is observed in that population is increasingly being concentrated in densely populated areas of intense economic activities. The implications of these trends for public action are analyzed in the final section.

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

    Science.gov (United States)

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

    2008-08-01

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

  7. Association with pathogenic bacteria affects life-history traits and population growth in Caenorhabditis elegans.

    Science.gov (United States)

    Diaz, S Anaid; Mooring, Eric Q; Rens, Elisabeth G; Restif, Olivier

    2015-04-01

    Determining the relationship between individual life-history traits and population dynamics is an essential step to understand and predict natural selection. Model organisms that can be conveniently studied experimentally at both levels are invaluable to test the rich body of theoretical literature in this area. The nematode Caenorhabditis elegans, despite being a well-established workhorse in genetics, has only recently received attention from ecologists and evolutionary biologists, especially with respect to its association with pathogenic bacteria. In order to start filling the gap between the two areas, we conducted a series of experiments aiming at measuring life-history traits as well as population growth of C. elegans in response to three different bacterial strains: Escherichia coli OP50, Salmonella enterica Typhimurium, and Pseudomonas aeruginosa PAO1. Whereas previous studies had established that the latter two reduced the survival of nematodes feeding on them compared to E. coli OP50, we report for the first time an enhancement in reproductive success and population growth for worms feeding on S. enterica Typhimurium. Furthermore, we used an age-specific population dynamic model, parameterized using individual life-history assays, to successfully predict the growth of populations over three generations. This study paves the way for more detailed and quantitative experimental investigation of the ecology and evolution of C. elegans and the bacteria it interacts with, which could improve our understanding of the fate of opportunistic pathogens in the environment.

  8. Life-shortening Wolbachia infection reduces population growth of Aedes aegypti.

    Science.gov (United States)

    Suh, Eunho; Mercer, David R; Dobson, Stephen L

    2017-08-01

    Wolbachia bacteria are being introduced into natural populations of vector mosquitoes, with the goal of reducing the transmission of human diseases such as Zika and dengue fever. The successful establishment of Wolbachia infection is largely dependent on the effects of Wolbachia infection to host fitness, but the effects of Wolbachia infection on the individual life-history traits of immature mosquitoes can vary. Here, the effects of life-shortening Wolbachia (wMelPop) on population growth of infected individuals were evaluated by measuring larval survival, developmental time and adult size of Aedes aegypti in intra- (infected or uninfected only) and inter-group (mixed with infected and uninfected) larval competition assays. At low larval density conditions, the population growth of wMelPop infected and uninfected individuals was similar. At high larval densities, wMelPop infected individuals had a significantly reduced population growth rate relative to uninfected individuals, regardless of competition type. We discuss the results in relation to the invasion of the wMelPop Wolbachia infection into naturally uninfected populations. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    Howat, Peter; Stoneham, Melissa

    2011-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Eleanor S Devenish Nelson

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

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

    Science.gov (United States)

    Stutz, Aaron Jonas

    2014-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Giovana Vera

    2014-06-01

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

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    The rapidly growing human population in sub-Saharan Africa generates increasing demand for agricultural land and forest products, which presumably leads to deforestation. Conversely, a greening of African drylands has been reported, but this has been difficult to associate with changes in woody...... an increase in woody cover largely in drylands, and 11% had a decrease (2,150,000 km2), mostly in humid zones. Increases in woody cover were associated with low population growth, and were driven by increases in CO2 in the humid zones and by increases in precipitation in drylands, whereas decreases in woody...... cover were associated with high population growth. The spatially distinct pattern of these opposing trends reflects, first, the natural response of vegetation to precipitation and atmospheric CO2, and second, deforestation in humid areas, minor in size but important for ecosystem services...

  15. Population growth of Nassella trichotoma in grasslands in New Zealand slower today than in the past

    Science.gov (United States)

    Lamoureaux, Shona L.; Bourdôt, Graeme W.; Saville, David J.

    2011-09-01

    Nassella trichotoma established in modified tussock-grasslands in New Zealand from about 1860. Management programmes since 1946 have reduced populations to levels no longer impacting pastoral production. Optimising future management requires knowledge of the trajectory of population growth and its regulating demographic processes. To that end, four long-term field experiments were conducted. Net reproductive rate varied from 1.021 to 1.237 year -1 and growth in plant basal diameter from 8.1 to 16.6 mm year -1. The probability of flowering increased with basal diameter and was essentially unity above 50 mm diameter. Populations grubbed annually declined abruptly but recruitment was unaffected and extinction did not occur. Of seeds sown into disturbed and intact pastures, 0-51% produced seedlings and more arose on sunny slopes and from disturbed than intact pasture. Death rates were high; 7 years after sowing, surviving plants represented only 0-9% of the seed sown. Seeds buried 25 mm deep in the pasture litter on two occasions declined in viability at rates of 74 and 89% in the first year and first three months respectively and 26 and 0% year -1 thereafter. Seed production plant -1 (square root scale) increased linearly with plant basal diameter; for example, plants of 11 and 100 mm diameter are predicted to produce 0 and 11,092 spikelets (each with one seed) respectively. We estimate that a N. trichotoma population today will, in the absence of management, take 210 years to increase to 90% of its carrying capacity supporting the hypothesis that population growth in this species is slower than occurred historically. We show that the rates of some demographic processes may be much lower than in the past and suggest this is due to more competitive vegetation resulting from improved management. The size-dependence of many processes supports the need for a size-structured model to explain population growth in this weed.

  16. Towards a Quantitative Use of Satellite Remote Sensing in Crop Growth Models for Large Scale Agricultural Production Estimate (Invited)

    Science.gov (United States)

    Defourny, P.

    2013-12-01

    such the Green Area Index (GAI), fAPAR and fcover usually retrieved from MODIS, MERIS, SPOT-Vegetation described the quality of the green vegetation development. The GLOBAM (Belgium) and EU FP-7 MOCCCASIN projects (Russia) improved the standard products and were demonstrated over large scale. The GAI retrieved from MODIS time series using a purity index criterion depicted successfully the inter-annual variability. Furthermore, the quantitative assimilation of these GAI time series into a crop growth model improved the yield estimate over years. These results showed that the GAI assimilation works best at the district or provincial level. In the context of the GEO Ag., the Joint Experiment of Crop Assessment and Monitoring (JECAM) was designed to enable the global agricultural monitoring community to compare such methods and results over a variety of regional cropping systems. For a network of test sites around the world, satellite and field measurements are currently collected and will be made available for collaborative effort. This experiment should facilitate international standards for data products and reporting, eventually supporting the development of a global system of systems for agricultural crop assessment and monitoring.

  17. The Visible minority population in Canada: a review of numbers, growth and labour force issues

    Directory of Open Access Journals (Sweden)

    Basavarajappa, Kogular

    2006-01-01

    Full Text Available EnglishIn this paper, the Visible Minority Population in Canada: Numbers, Growth andLabour Force Issues, the characteristics of the visible minority population andlabour force are examined including those employed by firms under theLegislated Employment Equity Program and the Federal Contractors Program.The future growth of the visible minority labour force and the socio-economicimpact of the findings are discussed along with their implications.FrenchDans cet article : La population de minorité visible au Canada : nombres,croissance et problèmes de la population active, les caractéristiques de lapopulation générale et de la population active des minorités visibles sontexaminées y compris celles qui sont utilisées par les firmes sous le Programmelégiféré d’équité en matière d’emploi et le Programme de contrats fédéraux. Lacroissance future de la population active de minorité visible et l’impact socioéconomique des conclusions sont discutées ainsi que leurs implications.

  18. EVALUATION COMPREHENSION OF THE CHILDREN AND ADOLESCENT PHYSICAL GROWTH IN THE COURSE OF THE POPULATION RESEARCH

    Directory of Open Access Journals (Sweden)

    V.R. Kuchma

    2008-01-01

    Full Text Available The urgency of the given research is intimately related to the necessity to choose the comprehension approaches to the evaluation of the children's physical growth, which may be applied in monitoring of the children collectives health status, planning and performance of the preventive and sanitary events at the group and population levels. The authors studied the socially different children collectives and examined 3,600 children and adolescents. They showed that the use of the regional modified regression scales, complex schemes and centile tables, i.e. regional standards based approaches to the evaluation of the physical growth would be comprehensive for the physical growth features of the children collectives subject to ethnic, climate and geographic as well as social and economic differences.Key words: physical growth, evaluation approaches, children, adolescents.

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

    Science.gov (United States)

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

    2017-04-01

    Identifying climatic drivers of an animal population's vital rates and locating where they operate steers conservation efforts to optimize species recovery. The population growth of endangered whooping cranes (Grus americana) hinges on juvenile recruitment. Therefore, we identify climatic drivers (solar activity [sunspots] and weather) of whooping crane recruitment throughout the species' life cycle (breeding, migration, wintering). Our method uses a repeated cross-validated absolute shrinkage and selection operator approach to identify drivers of recruitment. We model effects of climate change on those drivers to predict whooping crane population growth given alternative scenarios of climate change and solar activity. Years with fewer sunspots indicated greater recruitment. Increased precipitation during autumn migration signified less recruitment. On the breeding grounds, fewer days below freezing during winter and more precipitation during breeding suggested less recruitment. We predicted whooping crane recruitment and population growth may fall below long-term averages during all solar cycles when atmospheric CO2 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.

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

    Science.gov (United States)

    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.

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

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    FC. Massaro

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

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

    Science.gov (United States)

    Massaro, F C; Rocha, O

    2008-05-01

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

  3. [Some fundamental problems concerning the relationship between population growth and economic development].

    Science.gov (United States)

    Huang, Z

    1983-05-29

    The population growth rate is closely related to the quality of economic life, available funds for individual and social consumption, national income to be used for reproduction, and the labor employment situation. Since liberation, socialism has not been able to show its superiority, mainly because of China's large population figure, low economic productivity, low national income, and poor management in the relationship between consumption and accumulation. In order to solve these problems, we need to adequately control the pace of the population growth and match the rate of population growth with the pace of economic development. A way to increase national income is through saving and avoiding unnecessary waste. Social expenditures on education, culture, science, health and medical care, social welfare, and investment in the promotion of people's wisdom should all be increased. Meanwhile, the living standard of the people needs to be raised, and capital accumulation should also be managed so that funds will be available for industrial and economic enterprises. Existing inefficient production enterprises should be properly reorganized so that full employment may be achieved. In this way, the national economy will have more prosperity, and the people will benefit more from the Socialist policy.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    Barr, Brannon; Wolverton, Steve

    2014-10-01

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

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

    KAUST Repository

    Baumgarten, Sebastian

    2013-12-04

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

  7. Association between mandibular posterior alveolar morphology and growth pattern in a Chinese population with normal occlusion

    Institute of Scientific and Technical Information of China (English)

    Min HAN; Dong-xu LIU; Chun-ling WANG; Rong-yang WANG; Hong LIU; Xiu-juan ZHU; Fu-lan WEI; Tao LV; Na-na WANG; Li-hua HU; Guo-ju LI

    2013-01-01

    Objective:To investigate the relationship between growth patterns and mandibular posterior tooth-alveolar bone complex morphology in a Chinese population with normal occlusion.Methods:Forty-five patients with normal occlusion (23 males,22 females) were included in this study.Among these patients,20 displayed the vertical growth pattern,and 20 had the horizontal growth pattern,while the remaining patients displayed the average growth pattern.All of the patients underwent dental cone beam computed tomography (CBCT),which included the region of the mandibular posterior teeth and the alveolar.A linear regression analysis and a correlation analysis between the facial height index (FHI) and the alveolar bone morphology were performed.Results:The inclination of the molars,the thickness of the cortical bone,and the height of the mandibular bone differed significantly between patients with the horizontal growth pattern and those with the vertical growth pattern (P<0.05).Significant positive correlations were found between:the FHI and the inclination of the molars; the FHI and the thickness of the cortical bone; and the FHI and the height of the mandibular bone.Conclusions:The mandibular posterior tooth-alveolar bone complex morphology may be affected by growth patterns.

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

    Science.gov (United States)

    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

  9. Satellite monitoring of glaciers in the Karakoram from 1977 to 2013: an overall almost stable population of dynamic glaciers

    Directory of Open Access Journals (Sweden)

    R. M. Brahmbhatt

    2015-03-01

    Full Text Available Six hundred and seven glaciers of the Shigar, Shashghan, Nubra and part of Shyok sub-basins of the Karakoram region were monitored using satellite data of years 1977, 1990, 2000, 2001, 2002, 2004, 2006, 2008, 2009, 2010, 2011 and 2013. Landsat MSS, TM, ETM+ and IRS/Resourcesat-1 LISS III data were used. Glacier observations were classified into 3 categories such as advance, retreat or stable with reference to base data of 1977. Glaciers of the Karakoram have shown inconsistency in advance, retreat and no change during this period, and some examples of glacier surging have been caught in action. Despite significant geographic and temporal variability betraying the dynamic nature of many of the glaciers, in aggregate the population is roughly stable with less propensity toward retreat than most other glaciers in the nearby Himalaya and in the world. 341 glaciers exhibited no measured change throughout the 36 years of the study. Among other glaciers, no significant and sustained pattern of retreat or advance was observed. The overall changes in glacier area in the whole region are of small magnitudes (positive and negative values in the various measured intervals. Moreover, it is mostly disconnected glaciers in tributary valleys which have advanced, whereas the main former trunk glaciers have primarily not changed. The dynamical differences between disconnected former tributaries and trunks may be related to response time differences, with the smaller, perhaps steeper tributaries responding more rapidly than trunks to brief climatic fluctuations. The advance/retreat fluctuations of many individual glaciers suggest that their response times primarily may be of order decades rather than some longer period, though some glaciers may have longer response times that have limited their length and area changes over the 36 year study period. The data from 2001 onwards were also utilized for finding annual changes of glaciers. Among the 607 glaciers, 10 show

  10. Econometric Based Modeling of Population Growth under Socio-cultual Constraints

    CERN Document Server

    Ausloos, Marcel; Herteliu, Claudiu; Ileanu, Bogdan Vasile

    2015-01-01

    There are many constraints on population growth or decay in a country: several are of socio-economic origins. Sometimes cultual constraints also exist: sexual intercourse is banned in various religions, during Nativity and Lent fasting periods. We analyzed data consisting of registered daily birth records for very long (35,429 points) time series and many (24,947,061) babies in Romania between 1905 and 2001 (97 years). The data was obtained from the 1992 and 2002 censuses. We grouped the population into two categories (Eastern Orthodox and Non-Orthodox) in order to distinguish cultual constraints. We performed extensive data analysis in a comparative manner for both groups. From such a long time series data analysis, it seems that the Lent fast has a more drastic effect than the Nativity fast over baby conception within the Eastern Orthodox population, thereby differently increasing the population ratio. Thereafter, we developed and tested econometric models where the dependent variable is the baby conception...

  11. Trans-theta logistics: a new family of population growth sigmoid functions.

    Science.gov (United States)

    Kozusko, F; Bourdeau, M

    2011-12-01

    Sigmoid functions have been applied in many areas to model self limited population growth. The most popular functions; General Logistic (GL), General von Bertalanffy (GV), and Gompertz (G), comprise a family of functions called Theta Logistic ([Formula: see text] L). Previously, we introduced a simple model of tumor cell population dynamics which provided a unifying foundation for these functions. In the model the total population (N) is divided into reproducing (P) and non-reproducing/quiescent (Q) sub-populations. The modes of the rate of change of ratio P/N was shown to produce GL, GV or G growth. We now generalize the population dynamics model and extend the possible modes of the P/N rate of change. We produce a new family of sigmoid growth functions, Trans-General Logistic (TGL), Trans-General von Bertalanffy (TGV) and Trans-Gompertz (TG)), which as a group we have named Trans-Theta Logistic (T [Formula: see text] L) since they exist when the [Formula: see text] L are translated from a two parameter into a three parameter phase space. Additionally, the model produces a new trigonometric based sigmoid (TS). The [Formula: see text] L sigmoids have an inflection point size fixed by a single parameter and an inflection age fixed by both of the defining parameters. T [Formula: see text] L and TS sigmoids have an inflection point size defined by two parameters in bounding relationships and inflection point age defined by three parameters (two bounded). While the Theta Logistic sigmoids provided flexibility in defining the inflection point size, the Trans-Theta Logistic sigmoids provide flexibility in defining the inflection point size and age. By matching the slopes at the inflection points we compare the range of values of inflection point age for T [Formula: see text] L versus [Formula: see text] L for model growth curves.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Claudio Jose Struchiner

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

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

    Science.gov (United States)

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

    2014-08-01

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

  15. Growth regression models at two generations of selected populations Alabio ducks

    Directory of Open Access Journals (Sweden)

    L Hardi Prasetyo

    2007-12-01

    Full Text Available A selection process to increase egg production of Alabio ducks was conducted in Balai Penelitian Ternak, Ciawi-Bogor. The selection aimed at increasing production, however observation on growth of the selected ducks was necessary since early growth stage (0-8 wks determines the performance during laying period. This paper presents the growth models and the coefficient of determination of two generations of selected Alabio ducks. Body weight were observed weekly on 363 ducks from F1 and 356 ducks from F2, between 0-8 weeks and then fortinghly until 16 weeks. Growth curves were analysed using regression models between age and bodyweight of each population. The selection of model with the best fit was based on the large value of determination coefficient (R2, small value of MSE, and sinificant level of regression coefficient. Result showed that cubic polynomial regression was the best fit for the two populations, Y = 56.31-1.44X+0.64X2-0.005X3 for F1 and Y = 43.05 + 0.96X + 0.69X2 - 0.0056X3 for F2. The values of R2 were 0.9466 for F1 and 0.9243 for F2, and the values of MSE were 11.586 for F1 and 19.978 for F2. The growth of F1 is better during starter period, but F2 is better during grower period.

  16. Measuring selection in human populations using the growth rate per generation.

    Science.gov (United States)

    Ewbank, Douglas

    2016-04-19

    Estimates of the speed of evolution between generations depend on the association between individual traits and a measure of fitness. The two most frequently used measures of fitness are the net reproduction rate and the 1-year growth factor implied by the fertility and mortality rates. Results based on the two lead to very different results. The reason is that the 1-year growth factor is not a measure of change between generations. Therefore, studies of changes between generations should use the amount of growth over the length of a generation. This is especially important for studies of human populations because of the long length of generation. In addition, estimates based on a single year's growth are overly sensitive to data on individuals who fail to reproduce. The effects of using a generational measure are demonstrated using data from Kenya and Ukraine. These results demonstrate that using a 1-year growth rate to measure fitness leads to estimates that understate the rate at which evolution changes the characteristics of a human population.

  17. The factors of urban population growth: net inmigration versus natural increase.

    Science.gov (United States)

    Ledent, J

    1982-10-01

    "As a country evolves from a traditional to an advanced society, the part of urban growth that is due to net inmigration follows a simple pattern, which can be described by an inverted U-shaped curve: it first increases, then passes through a maximum, and decreases thereafter. This hypothesis is confirmed by quantitative analysis using time-series and cross-section data. The analysis suggests that in the second half of this century natural increase often provides a slightly higher contribution to urban population growth than net inmigration." (summary in FRE, ITA, JPN, )

  18. Population growth and the environment: Can we eat the cake and have it?

    Directory of Open Access Journals (Sweden)

    Shmuel Amir

    1999-01-01

    Full Text Available Continuous population growth and the concomitant maintenance of a growth sustaining environment are not in conflict only if the rates of both economic and biological processes are slowed down steadily. For this to happen, individual and social impatience-lowering adaptations should be adopted, and the capital of the system, both economic and natural, has to be redistributed among the system interacting components to result in an ever more complex organizational web. In addition, these factors have to corroborate with a third element, the incorporation of an arsenal of varied technological innovations that improves the use of existing stocks.

  19. Growth Strategy of Rhizomatous and Non-Rhizomatous Tall Fescue Populations in Response to Defoliation

    Directory of Open Access Journals (Sweden)

    Racheal H. Bryant

    2015-09-01

    Full Text Available The aim of this study was to determine the morphology of rhizome production, in two contrasting rhizomatous (R and non-rhizomatous (NR tall fescue (Schedonorus arundinaceus (Schreb. Dumort populations, and to assess whether rhizome production is associated with changed biomass allocation or plant growth pattern. Growth of R and NR populations was compared, under hard defoliation (H, 50 mm stubble, lax defoliation (L, 100 mm stubble, or without defoliation (U, uncut. Populations were cloned and grown in a glasshouse and defoliated every three weeks, with destructive harvests performed at 6, 12 and 18 weeks. R plants allocated more biomass to root and less to pseudostem than NR plants. Plant tiller numbers were greatly reduced by defoliation, and R and NR populations differed in leaf formation strategy. R plants had narrower leaves than NR, but their leaves were longer, because of greater leaf elongation duration. R plants were more plastic than NR plants in response to defoliation. Ultimately, biomass allocation to rhizomes did not differ between populations but R plants exhibited a subtle shift in distribution of internode length with a few longer internode segments typically located on secondary and tertiary tillers.

  20. Effects of population increase on cui-ui growth and maturation

    Science.gov (United States)

    Scoppettone, G.G.; Rissler, P.H.

    2007-01-01

    Cui-ui Chasmistes cujus is endemic to Pyramid Lake, Nevada. The cui-ui population declined during much of the 20th century as a result of water diversion and the formation of a shallow and virtually impassable delta at the mouth of the Truckee River, its spawning habitat. The population increased more than 10-fold to more than 1 million adults after access to the river was restored, creating a period of relatively higher density. This change presented the opportunity to test intraspecific density effects on cui-ui age and length at maturity and on growth. We also compared the year-class structure of the adult population before and after improved access. At low density, cui-ui mean age at maturation was 9.2 years for males and 9.6 for females; at high density, it was significantly higher: 11.8 years for males and 12.0 for females. There was no significant change in mean fork length at maturity related to population increase. Growth patterns differed between high and low density, the low-density fish growing faster than high-density fish before their respective mean age of maturity; past their mean age at maturity, high-density fish grew significantly faster than low-density fish. Fish in both density periods reached similar lengths by about 19-20 years of age. Year-class structure for both density periods consisted of strong year-classes, which predominated the adult population for several years.

  1. On the bubble? With healthcare job growth outstripping population in aging Rust Belt cities, some question the trend's durability.

    Science.gov (United States)

    Carlson, Joe; Kutscher, Beth

    2013-03-01

    Aging Rust Belt cities are some of the leaders in healthcare job growth despite stagnant or decreasing populations, even amid mounting pressure to cut healthcare costs. Areas seeing rapid population growth aren't as dependent on healthcare. "Cities that are growing quickly are most likely adding diversified industries," says Dr. Sheldon Retchin, of the Virginia Commonwealth University Health System.

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

    NARCIS (Netherlands)

    Van Hinsberg, A.

    1997-01-01

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

  3. Simultaneous inference of selection and population growth from patterns of variation in the human genome

    DEFF Research Database (Denmark)

    Williamson, Scott H.; Hernandez, Ryan; Fledel-Alon, Adi

    2005-01-01

    for patterns of polymorphism in the presence of both population size change and natural selection. If data are available from different functional classes of variation, and a priori information suggests that mutations in one of those classes are selectively neutral, then the putatively neutral class can...... this method to a large polymorphism data set from 301 human genes and find (i) widespread negative selection acting on standing nonsynonymous variation, (ii) that the fitness effects of nonsynonymous mutations are well predicted by several measures of amino acid exchangeability, especially site......-specific methods, and (iii) strong evidence for very recent population growth....

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

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

    OpenAIRE

    Izmirlioglu, Yusuf

    2008-01-01

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

  6. Evidence of exponential growth of an anammox population in an anaerobic batch culture.

    Science.gov (United States)

    Yasuda, Tomoko; Waki, Miyoko; Yoshinaga, Ikuo; Amano, Teruki; Suzuki, Kazuyoshi; Tanaka, Yasuo; Yamagishi, Takao; Suwa, Yuichi

    2011-01-01

    Twenty-five replicates of growth medium for anaerobic ammonium oxidation (anammox) containing (15)N-labeled ammonium and non-labeled nitrite were inoculated into an anammox enrichment culture at low density, and anaerobically incubated batchwise. In the headspace, (29)N(2) partial pressure linearly increased via anammox in 25 vials, confirming that anammox populations were viable in all subcultures. On prolonged incubation, exponential increases in (29)N(2) were not observed in all but 13 subcultures, suggesting that the anammox population may not proliferate unless all conditions for growth are satisfied. The estimated first-order rate coefficients in those 13 subcultures varied from 0.0029 to 0.0048 h(-1).

  7. Bot fly parasitism of the red-backed vole: host survival, infection risk, and population growth.

    Science.gov (United States)

    Lemaître, Jérôme; Fortin, Daniel; Montiglio, Pierre-Olivier; Darveau, Marcel

    2009-03-01

    Parasites can play an important role in the dynamics of host populations, but empirical evidence remains sparse. We investigated the role of bot fly (Cuterebra spp.) parasitism in red-backed voles (Myodes gapperi) by first assessing the impacts of the parasite on the probability of vole survival under stressful conditions as well as on the reproductive activity of females. We then identified the main factors driving both the individual risk of infection and the abundance of bot flies inside red-backed voles. Finally, we evaluated the impacts of bot fly prevalence on the growth rate of vole populations between mid-July and mid-August. Thirty-six populations of red-backed voles were sampled in the boreal forest of Québec, Canada. The presence and the abundance of parasites in voles, two host life history traits (sex and body condition), three indices of habitat complexity (tree basal area, sapling basal area, coarse woody debris volume), and vole abundance were considered in models evaluating the effects of bot flies on host populations. We found that the probability of survival of red-backed voles in live traps decreased with bot fly infection. Both the individual risk of infection and the abundance of bot flies in red-backed voles were driven mainly by vole abundance rather than by the two host life history traits or the three variables of habitat complexity. Parasitism had population consequences: bot fly prevalence was linked to a decrease in short-term growth rate of vole populations over the summer. We found that bot flies have the potential to reduce survival of red-backed voles, an effect that may apply to large portions of populations.

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

    Directory of Open Access Journals (Sweden)

    Radek Bukowski

    2014-04-01

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

  9. Fetal Growth and Risk of Stillbirth: A Population-Based Case–Control Study

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2014-04-01

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

  11. Effects of human population growth on the Fraser and Okanagan River systems, Canada: a comparative inquiry.

    Science.gov (United States)

    Northcote, T G

    1996-10-01

    The author compares the impact of human population growth on the Fraser and Okanagan river systems in Canada. The effects "on water, fisheries and other aquatic resources of the two basins are explored along with possibilities and suggestions for their sustainable development. The latter, despite some glimmers of hope, will not be tenable without major changes in public attitude, in government policy at all levels, and in other measures which to many may seem impossible." excerpt

  12. Natural Disasters, Forced migration and population growth in 21st century in India

    OpenAIRE

    Lokanath Suar

    2013-01-01

    The impact of drought, floods, severe weather and other effects of climate change may worsen in the future, contributing to growing human migration as vulnerable people seek safer more stable living conditions. This expected migration of thousands of people can negatively affect human well-being and political status. The paper presents the effect and its management. Key words: natural disasters, forced migration, population growth

  13. Satellite NO2 data improve national land use regression models for ambient NO2 in a small densely populated country

    NARCIS (Netherlands)

    Hoek, Gerard; Eeftens, Marloes; Beelen, Rob; Fischer, Paul; Brunekreef, Bert; Boersma, K. Folkert; Veefkind, Pepijn

    2015-01-01

    Land use regression (LUR) modelling has increasingly been applied to model fine scale spatial variation of outdoor air pollutants including nitrogen dioxide (NO2). Satellite observations of tropospheric NO2 improved LUR model in very large study areas, including Canada, United States and Australia.

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

    Science.gov (United States)

    He, Ling-Yun; Wen, Xing-Chun

    2017-03-01

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

  15. Vulnerability of Korean water resources to climate change and population growth.

    Science.gov (United States)

    Chang, H; Franczyk, J; Im, E-S; Kwon, W-T; Bae, D-H; Jung, I-W

    2007-01-01

    Freshwater availability is affected by changes in climate and growth. We assessed the freshwater vulnerability for five major Korean river basins for 2015 and 2030. We used a regional climate model based on the IPCC SRES A2 scenario, US Geological Survey's Precipitation Rainfall Simulation Model, and population and industrial growth scenarios for impact assessment. The model simulation results suggest increasing spatial and temporal variations of water stress for the basins that are already developed. While freshwater is more vulnerable to growth scenarios than the climate change scenario, climate change alone could decrease mean annual runoff by 10% in four major river basins by 2030. As the first national assessment of climate change, we suggest possible adaptive water resource management and policy strategies for reducing climate related risks in Korea.

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

    Directory of Open Access Journals (Sweden)

    Hsin Y. Tsai

    2015-12-01

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

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

    Science.gov (United States)

    Brendan, Lo Rick; Sek, Siok Kun

    2017-08-01

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

  18. Avoid population growth to reduce water stress and food demand. Prof. Malin Falkenmark on water, food and population.

    Science.gov (United States)

    1996-01-01

    Global food security is closely linked to the overall availability of water. In some regions of the world, water scarcity will increasingly constrain crop production, forcing a dependency upon food imports. This problem will be particularly acute in dry-climate countries with rapid population growth. Water availability is therefore a fundamental condition for socioeconomic development which requires policymaker attention. Crops depend upon soil moisture and aquifers and rivers. Poor rainfalls and depleted aquifers threaten crop yields. The larger the population, the more water is needed for social and economic needs, including irrigation. However, water for irrigation competes with the water needs of households and industry. Recent research indicates that many dry-climate countries are moving farther away from the possibility of food self-sufficiency. These countries should study their comparative advantages to determine what to export in exchange for food imports from the sub-humid and humid regions of the world. Governments should also promote family planning and the small family norm with the goal of reducing water stress and food demand.

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

    Directory of Open Access Journals (Sweden)

    Simone Vincenzi

    2014-09-01

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

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

    Science.gov (United States)

    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

  1. Influence of molecular noise on the growth of single cells and bacterial populations.

    Directory of Open Access Journals (Sweden)

    Mischa Schmidt

    Full Text Available During the last decades experimental studies have revealed that single cells of a growing bacterial population are significantly exposed to molecular noise. Important sources for noise are low levels of metabolites and enzymes that cause significant statistical variations in the outcome of biochemical reactions. In this way molecular noise affects biological processes such as nutrient uptake, chemotactic tumbling behavior, or gene expression of genetically identical cells. These processes give rise to significant cell-to-cell variations of many directly observable quantities such as protein levels, cell sizes or individual doubling times. In this study we theoretically explore if there are evolutionary benefits of noise for a growing population of bacteria. We analyze different situations where noise is either suppressed or where it affects single cell behavior. We consider two specific examples that have been experimentally observed in wild-type Escherichia coli cells: (i the precision of division site placement (at which molecular noise is highly suppressed and (ii the occurrence of noise-induced phenotypic variations in fluctuating environments. Surprisingly, our analysis reveals that in these specific situations both regulatory schemes [i.e. suppression of noise in example (i and allowance of noise in example (ii] do not lead to an increased growth rate of the population. Assuming that the observed regulatory schemes are indeed caused by the presence of noise our findings indicate that the evolutionary benefits of noise are more subtle than a simple growth advantage for a bacterial population in nutrient rich conditions.

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

    Science.gov (United States)

    Shaw, R P

    1992-02-01

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

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

    Science.gov (United States)

    Leta, Samson; Mesele, Frehiwot

    2014-01-01

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

  4. Vascular endothelial growth factor-A is associated with chronic mountain sickness in the Andean population.

    Science.gov (United States)

    Espinoza, Jose R; Alvarez, Giancarlo; León-Velarde, Fabiola; Preciado, Hugo F Ju; Macarlupu, Jose-Luis; Rivera-Ch, Maria; Rodriguez, Jorge; Favier, Judith; Gimenez-Roqueplo, Anne-Paule; Richalet, Jean-Paul

    2014-06-01

    A study of chronic mountain sickness (CMS) with a candidate gene--vascular endothelial growth factor A (VEGFA)--was carried out in a Peruvian population living at high altitude in Cerro de Pasco (4380 m). The study was performed by genotyping of 11 tag SNPs encompassing 2.2 kb of region of VEGFA gene in patients with a diagnosis of CMS (n = 131; 49.1 ± 12.7 years old) and unrelated healthy controls (n = 84; 47.2 ± 13.4 years old). The VEGFA tag SNP rs3025033 was found associated with CMS (p Cerro de Pasco population and HapMap3 population (Fst > 0.36, p < 0.01), suggesting selection is operating on the VEGF gene. Our results suggest that VEGFA is associated with CMS in long-term residents at high altitude in the Peruvian Andes.

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

    Directory of Open Access Journals (Sweden)

    N. A. Serebryakova

    2015-01-01

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

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

    Science.gov (United States)

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

    2008-01-01

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

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

    Science.gov (United States)

    Bagan, H.; Yamagata, Y.

    2012-12-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  10. Genetic analysis of leg problems and growth in a random mating broiler population.

    Science.gov (United States)

    González-Cerón, F; Rekaya, R; Anthony, N B; Aggrey, S E

    2015-02-01

    Improvement in growth has been widely reported as the cause of increased incidence of leg problems in broiler chickens. We report herein the genetic relationship between growth and leg problems in a random mating broiler control population. The traits studied were valgus (VL), varus (VR), and tibial dyschondroplasia (TD), which were expressed on a binary scale of 0 (normal) and 1 (abnormal); growth rates from 0 to 4 wk (BWG 0-4) and from 0 to 6 wk of age (BWG 0-6); and residual feed intake from 5 to 6 wk of age (RFI 5-6). A threshold-linear mixed model was employed for the joint analysis of the categorical and linear traits. Incidences of VL, VR, and TD were 26, 4, and 2%, respectively. Heritability of leg problems ranged from 0.11 to 0.13. Phenotypic correlations alluded to an unfavorable relationship between growth and leg problems; however, the genetic relationship between growth and leg problems was extremely weak, ranging from 0.01 to 0.08. There is, therefore, a basis for genetic improvement in leg problems. However, improved management practices would also be important to reduce incidence of leg problems in broiler chickens.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Rishikesh Pandey

    2014-05-01

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

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

    Science.gov (United States)

    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.

  14. Population size and growth in Pakistan based on early reports of 1972 census.

    Science.gov (United States)

    Krotki, K J; Parveen, K

    1976-01-01

    The 1972 census of Pakistan showed a population of 64.9 million, surprisingly high considering family planning campaigns, 2 wars with India, only minor gains in migration from Bangladesh, and the fact that other nearby countries have shown slowed population growth. This paper discusses many variables which may relate to the reliability of this figure. Census data in Pakistan has been traditionally difficult to obtain. For this reason growth rates rather than gross numbers are used for this analysis because these seem to move in relationship to total population and are more easily obtained. Before the 1961 census it was hopefully assumed that the growth rate was 1.4% per year. Between 1951 and 1961 however it was 2.2% and may have been as high as 2.8% or 3.2%. The 1972 census gives age distributions for only 23 of 61 districts but by comparing data for these 23 districts certain trends can be distinguished. Data for age group 0-5 years is often underreported so the actual population increase is picked up in the 5-9 and 10-15 age groups. In both 1961 and 1972 the 5-9 age group is very large. Either there is overreporting in this age group or these children were actually born when demographers were claiming success for the family planning program. There is a drop for those aged 15 in 1961, a similar but not so pronounced drop in 1971, another drop for those aged 40, and another drop for those aged 50. The reason for this ''zig-zag'' phenomena is not clear. The male-female ratios at older ages are more in line with the rest of the world in the 1972 census. This may be because older women were less forgotten than in the 1961 census. Charts and graphs detail the statistics. Ways of improving census data in the future are discussed.

  15. The future fertility of mankind: effects on world population growth and migration.

    Science.gov (United States)

    Short, R V

    2001-01-01

    The world's population, currently just over 6 billion, is projected to increase to 9-10 billion by the year 2050. Most of this growth will occur in the developing countries of Asia, where there is an enormous unmet demand for contraception, while an increasing number of developed countries will have declining populations. The human immunodeficiency virus (HIV) pandemic will target developing countries, with India destined to become its new epicenter. By 2050, there may be 1 billion HIV-infected people in the world. The significant protective effect of male circumcision may spare Islamic countries, such as Pakistan, Bangladesh, Iran and Indonesia, from the worst effects of the pandemic. Australia will be increasingly threatened by the high rates of population growth of her Asian neighbours. This, coupled with political instability and sea-level rises as a consequence of global warming, will turn the present trickle of refugees from a variety of Asian countries seeking safe haven on our sparsely populated northern coastline into a veritable flood. There will come a time when we have neither the manpower, nor the means, nor even the moral right to intercept, detain or repatriate the thousands who will come in peace, in search of a better life. However, if Australia is to stabilize its future population at around 23 million, which seems highly desirable on ecological grounds, then the net immigration rate must be limited to approximately 50000 people per year. Because the final point of departure for all these refugees is Indonesia, it is essential that Australia maintains good relations with Indonesia, so that together we can attempt to manage the refugee problem. However, Indonesia's own population is destined to increase by 100 million in the next 50 years, which will only exacerbate the situation. Australia would be well advised to make a major increase in its paltry financial assistance to Indonesia's excellent family planning programmes, which are currently

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Hal Caswell

    2010-09-01

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

  18. Detecting tents to estimate the displaced populations for post-disaster relief using high resolution satellite imagery

    Science.gov (United States)

    Wang, Shifeng; So, Emily; Smith, Pete

    2015-04-01

    Estimating the number of refugees and internally displaced persons is important for planning and managing an efficient relief operation following disasters and conflicts. Accurate estimates of refugee numbers can be inferred from the number of tents. Extracting tents from high-resolution satellite imagery has recently been suggested. However, it is still a significant challenge to extract tents automatically and reliably from remote sensing imagery. This paper describes a novel automated method, which is based on mathematical morphology, to generate a camp map to estimate the refugee numbers by counting tents on the camp map. The method is especially useful in detecting objects with a clear shape, size, and significant spectral contrast with their surroundings. Results for two study sites with different satellite sensors and different spatial resolutions demonstrate that the method achieves good performance in detecting tents. The overall accuracy can be up to 81% in this study. Further improvements should be possible if over-identified isolated single pixel objects can be filtered. The performance of the method is impacted by spectral characteristics of satellite sensors and image scenes, such as the extent of area of interest and the spatial arrangement of tents. It is expected that the image scene would have a much higher influence on the performance of the method than the sensor characteristics.

  19. Comparative growth and viability of hybrids between two populations of Chinese shrimp (Fennropenaeus chinensis)

    Institute of Scientific and Technical Information of China (English)

    TIAN Yi; KONG Jie; YANG Cuihua

    2006-01-01

    Fenneropenaeus chinensis is confined to the Yellow Sea and Bohai Sea in China and the West Coast of the Korean Peninsula. Intra- and intercross populations were produced between Rushany (YP) and Korean (KN) populations. Seven traits were recorded. The heterosis of hybrids was computed and comparison between treatments was performed by ANOVA. At the fourth month after post-larvae, six indexes of growth trait and viability showed a range of heterosis, ranging from 0.514% to 14.950%. At the fifth month after post-larvae, six indexes of growth trait and viability ranged from -9.000% to 19.090%. The negative heterosis was observed in CL, HST and viability. The heterosis of KN♀×YP♂ tended generally to increase as the age of the Chinese shrimp increased while the heterosis of YP♀×KN♂ tended to decrease. The results indicated that the viability of reciprocal hybrids were not significantly different (P>0.05) from their parents during the experiment. The result of ANOVA indicated that the F1 hybrids were significantly different (P<0.05) in WST and TW at the fourth month. The multiple comparisons of LSD test indicated that the hybrids of YP♀×KN♂ were significantly different (P<0.05) from their parents in TW. The hybrids of YP♀×KN♂ were significantly different (P<0.05) from the other three combinations in WST. At the fifth months, the F1 hybrids had significant difference (P<0.05) in body weight while other traits showed no significant differences (P>0.05) from their parents. The multiple comparisons of LSD test indicated that the hybrids of KN♀×YP♂ were significantly different (P<0.05) from the KN parents in TW. The results indicate that in experimental conditions, the F1 hybrids created from two populations of Chinese shrimp showed a certain level of heterosis for growth performance and viability. The crossing scheme may improve growth performance and viability in Chinese shrimp, but the improvement may be limited because effective

  20. Agricultural adjuvants: acute mortality and effects on population growth rate of Daphnia pulex after chronic exposure.

    Science.gov (United States)

    Stark, John D; Walthall, William K

    2003-12-01

    Acute and chronic toxicity of eight agricultural adjuvants (Bond, Kinetic, Plyac, R-11, Silwet L-77, Sylgard 309, X-77, and WaterMaxx) to Daphnia pulex were evaluated with 48-h acute lethal concentration estimates (LC50) and a 10-d population growth-rate measurement, the instantaneous rate of increase (r1). Based on LC50, the order of toxicity was R-11 > X-77 = Sylgard 309 = Silwet L-77 > Kinetic > Bond > Plyac > WaterMaxx; all LC50 estimates were higher than the expected environmental concentration (EEC) of 0.79 mg/L, indicating that none of these adjuvants should cause high levels of mortality in wild D. pulex populations. Extinction, defined as negative population growth rate, occurred after exposure to 0.9 mg/L R-11, 13 mg/L X-77, 25 mg/L Kinetic, 28 mg/L Silwet, 18 mg/L Sylgard, 450 mg/L Bond, 610 mg/L Plyac, and 1,600 mg/L WaterMaxx. Concentrations that caused extinction were substantially below the acute LC50 for R-11, Kinetic, Plyac, X-77, and Bond. The no-observable-effects concentration (NOEC) and lowest-observable-effects concentration (LOEC) for the number of offspring per surviving female after exposure to R-11 were 0.5 and 0.75 mg/L, respectively. The NOEC and LOEC for population size after exposure to R-11 were (1.25 and 0.5 mg/L, respectively. Both of these values were lower than the EEC, indicating that R-11 does have the potential to cause damage to D. pulex populations after application at recommended field rates. The wide range of concentrations causing extinction makes it difficult to generalize about the potential impacts that agricultural adjuvants might have on aquatic ecosystems. Therefore, additional studies that examine effects on other nontarget organisms and determine residues in aquatic ecosystems may be warranted.

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

    Directory of Open Access Journals (Sweden)

    Nico Geisel

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

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

    Science.gov (United States)

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

    2011-04-15

    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.

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

    Directory of Open Access Journals (Sweden)

    Aldo Compagnoni

    2014-01-01

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

  4. Optical terminal definition for the Future Service Growth (FSG) module of the Advanced Tracking and Data Relay Satellite (ATDRSS)

    Science.gov (United States)

    Bruno, Ronald C.; Kalil, Ford

    1992-01-01

    Results are presented from preliminary analyses and definition studies for an optical terminal's incorporation into the FSG module of the ATDRS system, which must support crosslinks between selected relay satellites of a modified ATDRS constellation and thereby allow the placement of a relay satellite at an orbital location which eliminates the zone of exclusion. These studies have attempted to identify alternative constellations by means of one or more crosslinks, and to formulate the service-routing requirement for the FSG terminal. Attention is given to an FSG optical terminal that furnishes the functionality and performance required for a crosslink terminal.

  5. Optical terminal definition for the Future Service Growth (FSG) module of the Advanced Tracking and Data Relay Satellite (ATDRSS)

    Science.gov (United States)

    Bruno, Ronald C.; Kalil, Ford

    1992-01-01

    Results are presented from preliminary analyses and definition studies for an optical terminal's incorporation into the FSG module of the ATDRS system, which must support crosslinks between selected relay satellites of a modified ATDRS constellation and thereby allow the placement of a relay satellite at an orbital location which eliminates the zone of exclusion. These studies have attempted to identify alternative constellations by means of one or more crosslinks, and to formulate the service-routing requirement for the FSG terminal. Attention is given to an FSG optical terminal that furnishes the functionality and performance required for a crosslink terminal.

  6. Influence of projected ocean warming on population growth potential in two North Atlantic copepod species

    Science.gov (United States)

    Stegert, Christoph; Ji, Rubao; Davis, Cabell S.

    2010-10-01

    Copepods of the genera Pseudocalanus and Centropages play an important role in the North Atlantic ecosystems and have distinctive spatial and temporal patterns depending on physiological adaptation to different environmental conditions. To examine the possible impact of climate change on these biogeographic patterns, potential population growth rate was computed for each species using IPCC projections of sea surface temperature together with chlorophyll distributions from SeaWiFS climatology and published laboratory data on temperature and food-dependent life-history parameters. The results indicate that the predicted temperature increase throughout the North Atlantic will cause temporal and spatial shifts in copepod species population growth potential. The Centropages population is projected to increase in mid-latitudinal shelf areas, e.g. the Gulf of Maine and the North Sea, due to shorter generation times and a longer growing season, while Pseudocalanus is predicted to be less abundant in these regions after 2050. These shifts potentially have a significant impact on the future demographics of pelagic fish species for which the copepods are the major food source.

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

    Directory of Open Access Journals (Sweden)

    Wei-Bin Zhang

    2016-05-01

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

  8. High Population Density of Juvenile Chum Salmon Decreased the Number and Sizes of Growth Hormone Cells in the Pituitary

    OpenAIRE

    Salam, Md. Abdus; Ota, Yuki; Ando, Hironori; Fukuwaka, Masa-aki; Kaeriyama, Masahide; Urano, Akihisa

    1999-01-01

    Juveniles of chum salmon (Oncorhynchus keta) held at high population density were apparently smaller than those held at medium and low population densities. The effects of high population density on pituitary growth hormone (GH) cells in juvenile chum salmon were examined using immunocytochemical and in situ hybridization techniques. The ratio of GH-immunoreactive (ir) area to the whole pituitary was almost constant in all of the high, medium and low population density groups, although the nu...

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

    Science.gov (United States)

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

    2012-01-01

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

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

    DEFF Research Database (Denmark)

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

    2010-01-01

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

  11. Population growth rate and genetic variability of small and large populations of Red flour beetle (Tribolium castaneum) following multigenerational exposure to copper.

    Science.gov (United States)

    Laskowski, Ryszard; Radwan, Jacek; Kuduk, Katarzyna; Mendrok, Magdalena; Kramarz, Paulina

    2015-07-01

    We reared large (1000 individuals) and small (20 individuals) populations of Tribolium castaneum on diet contaminated with copper in order to determine if the size of a population affects its ability to adapt to adverse environmental conditions. After 10 generations, we used microsatellite markers to estimate and subsequently compare the genetic variability of the copper-treated populations with that of the control populations, which were reared on uncontaminated medium. Additionally, we conducted a full cross-factorial experiment which evaluated the effects of 10 generations of "pre-exposure" to copper on a population's fitness in control and copper-contaminated environments. In order to distinguish results potentially arising from genetic adaptation from those due to non-genetic effects associated to parental exposure to copper, we subjected also F11 generation, originating from parents not exposed to copper, to the same cross-factorial experiment. The effects of long-term exposure to copper depended on population size: the growth rates of small populations that were pre-exposed to copper were inhibited compared to those of small populations reared in uncontaminated environments. Large Cu-exposed populations had a higher growth rate in the F10 generation compared to the control groups, while the growth rate of the F11 generation was unaffected by copper exposure history. The only factor that had a significant effect on genetic variability was population size, but this was to be expected given the large difference in the number of individuals between large and small populations. Neither copper contamination nor its interaction with population size affected the number of microsatellite alleles retained in the F10 generation.

  12. Growth and Reproduction of Glyphosate-Resistant and Susceptible Populations of Kochia scoparia

    OpenAIRE

    Vipan Kumar; Prashant Jha

    2015-01-01

    Evolution of glyphosate-resistant kochia is a threat to no-till wheat-fallow and glyphosate-resistant (GR) cropping systems of the US Great Plains. The EPSPS (5-enol-pyruvylshikimate-3-phosphate synthase) gene amplification confers glyphosate resistance in the tested Kochia scoparia (L.) Schrad populations from Montana. Experiments were conducted in spring to fall 2014 (run 1) and summer 2014 to spring 2015 (run 2) to investigate the growth and reproductive traits of the GR vs. glyphosate-sus...

  13. Programmable models of growth and mutation of cancer-cell populations

    CERN Document Server

    Bortolussi, Luca; 10.4204/EPTCS.67.4

    2011-01-01

    In this paper we propose a systematic approach to construct mathematical models describing populations of cancer-cells at different stages of disease development. The methodology we propose is based on stochastic Concurrent Constraint Programming, a flexible stochastic modelling language. The methodology is tested on (and partially motivated by) the study of prostate cancer. In particular, we prove how our method is suitable to systematically reconstruct different mathematical models of prostate cancer growth - together with interactions with different kinds of hormone therapy - at different levels of refinement.

  14. A Stable Finite-Difference Scheme for Population Growth and Diffusion on a Map

    Science.gov (United States)

    Callegari, S.; Lake, G. R.; Tkachenko, N.; Weissmann, J. D.; Zollikofer, Ch. P. E.

    2017-01-01

    We describe a general Godunov-type splitting for numerical simulations of the Fisher–Kolmogorov–Petrovski–Piskunov growth and diffusion equation on a world map with Neumann boundary conditions. The procedure is semi-implicit, hence quite stable. Our principal application for this solver is modeling human population dispersal over geographical maps with changing paleovegetation and paleoclimate in the late Pleistocene. As a proxy for carrying capacity we use Net Primary Productivity (NPP) to predict times for human arrival in the Americas. PMID:28085882

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

    Science.gov (United States)

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

    2012-12-01

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

  16. Phylogenetic prediction of the maximum per capita rate of population growth.

    Science.gov (United States)

    Fagan, William F; Pearson, Yanthe E; Larsen, Elise A; Lynch, Heather J; Turner, Jessica B; Staver, Hilary; Noble, Andrew E; Bewick, Sharon; Goldberg, Emma E

    2013-07-22

    The maximum per capita rate of population growth, r, is a central measure of population biology. However, researchers can only directly calculate r when adequate time series, life tables and similar datasets are available. We instead view r as an evolvable, synthetic life-history trait and use comparative phylogenetic approaches to predict r for poorly known species. Combining molecular phylogenies, life-history trait data and stochastic macroevolutionary models, we predicted r for mammals of the Caniformia and Cervidae. Cross-validation analyses demonstrated that, even with sparse life-history data, comparative methods estimated r well and outperformed models based on body mass. Values of r predicted via comparative methods were in strong rank agreement with observed values and reduced mean prediction errors by approximately 68 per cent compared with two null models. We demonstrate the utility of our method by estimating r for 102 extant species in these mammal groups with unknown life-history traits.

  17. In the national interest: the PCSD puts population growth back on the agenda.

    Science.gov (United States)

    Dixon, B

    1995-01-01

    In 1972, President Nixon launched the Rockefeller Commission on Population Growth and the American Future. The US population has grown by more than 50 million people since 1972. In 1995, a report by the President's Council on Sustainable Development (PCSD) states that failure on the part of the US to stabilize its population will jeopardize any effort to achieve sustainable development. As a follow-up to the Earth Summit, President Clinton established the PCSD in 1993 to identify ways to encourage sustainable development in the US. The Council has 25 members representing government, business, and public interest organizations and has 8 critical issues task forces, including Energy, Transportation, Sustainable Community, Education and Outreach, Natural Resources, Eco Efficiency and Sustainable Agriculture. Timothy Wirth, Under Secretary of State for Global Affairs, spearheaded efforts to create a task force on the twin issues of population and consumption. The Population and Consumption Task Force, which began its official discussions in the spring of 1994, aimed to solicit public comment on critical population-related issues. These meetings sought both general public and expert participation on subjects such as teen pregnancy, resource use, and economic indicators. Among these recommendations are improving access to family planning services for all Americans; focusing on special efforts to reduce teen pregnancy and childbearing; improving external factors such as poverty and a lack of economic opportunities for girls and women; and reducing immigration to the US. A combination of actions are needed, including a tax shift from labor and earnings to natural resource use; development of environmentally sound technologies; and public understanding of the importance of sustainable life style and consumption choices. Individual and community action is crucial since the current Congress is unlikely to adopt policies to promote sustainable development without significant

  18. A guide for the analysis of long-term population growth in cancer.

    Science.gov (United States)

    Silva, Andrew O; Felipe, Karina B; Villodre, Emilly S; Lopez, Patricia L C; Lenz, Guido

    2016-10-01

    Although cancer is a chronic disease, most of the in vitro experiments to assess the effectiveness of intervention are performed in hours or a few days. Moreover, none of the available methodologies to measure cell proliferation are adapted to provide information about the growth kinetic during and after treatment. Thus, the objective of this work is to provide a guide to assess long-term changes in cell population size to be used mainly in cancer research. Cumulative population doubling (CPD) graphs based on cell counting for in vitro or tumor volume for in vivo assays were used to calculate four parameters: relative end CPD (RendCPD), to quantify the end point analysis of proliferation; relative area under curve (rAUC), to describe the global chronic effect of a treatment; relative time to cross a threshold (RTCT), to indicate the delay in cell population recovery produced by a treatment; and relative proliferation rate (RPR), to describe the relative regrowth velocity of the cells that survived after treatment. These parameters describe not only the acute and chronic effects of a treatment but also the behavior of cells that are not eliminated by the treatment, providing crucial information about the growth kinetic of the surviving population. Moreover, the proposed analysis allowed the grouping of independent CPD experiments quantified at different time points and even the direct comparison of in vitro and in vivo experiments. Therefore, this new way to analyze long-term outcomes provides a global view of the effectiveness of an intervention, as an important tool for long-term studies.

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

    Science.gov (United States)

    Patterson, J G; Shrestha, N R

    1988-01-01

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

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

    Science.gov (United States)

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

    2009-01-01

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

  1. Bushmeat poaching reduces the seed dispersal and population growth rate of a mammal-dispersed tree.

    Science.gov (United States)

    Brodie, Jedediah F; Helmy, Olga E; Brockelman, Warren Y; Maron, John L

    2009-06-01

    Myriad tropical vertebrates are threatened by overharvest. Whether this harvest has indirect effects on nonhunted organisms that interact with the game species is a critical question. Many tropical birds and mammals disperse seeds. Their overhunting in forests can cause zoochorous trees to suffer from reduced seed dispersal. Yet how these reductions in seed dispersal influence tree abundance and population dynamics remains unclear. Reproductive parameters in long-lived organisms often have very low elasticities; indeed the demographic importance of seed dispersal is an open question. We asked how variation in hunting pressure across four national parks with seasonal forest in northern Thailand influenced the relative abundance of gibbons, muntjac deer, and sambar deer, the sole dispersers of seeds of the canopy tree Choerospondias axillaris. We quantified how variation in disperser numbers affected C. axillaris seed dispersal and seedling abundance across the four parks. We then used these data in a structured population model based on vital rates measured in Khao Yai National Park (where poaching pressure is minimal) to explore how variation in illegal hunting pressure might influence C. axillaris population growth and persistence. Densities of the mammals varied strongly across the parks, from relatively high in Khao Yai to essentially zero in Doi Suthep-Pui. Levels of C. axillaris seed dispersal and seedling abundance positively tracked mammal density. If hunting in Khao Yai were to increase to the levels seen in the other parks, C. axillaris population growth rate would decline, but only slightly. Extinction of C. axillaris is a real possibility, but may take many decades. Recent and ongoing extirpations of vertebrates in many tropical forests could be creating an extinction debt for zoochorous trees whose vulnerability is belied by their current abundance.

  2. Satellite Communication.

    Science.gov (United States)

    Technology Teacher, 1985

    1985-01-01

    Presents a discussion of communication satellites: explains the principles of satellite communication, describes examples of how governments and industries are currently applying communication satellites, analyzes issues confronting satellite communication, links mathematics and science to the study of satellite communication, and applies…

  3. The uncertainty of future water supply adequacy in megacities: Effects of population growth and climate change

    Science.gov (United States)

    Alarcon, T.; Garcia, M. E.; Small, D. L.; Portney, K.; Islam, S.

    2013-12-01

    Providing water to the expanding population of megacities, which have over 10 million people, with a stressed and aging water infrastructure creates unprecedented challenges. These challenges are exacerbated by dwindling supply and competing demands, altered precipitation and runoff patterns in a changing climate, fragmented water utility business models, and changing consumer behavior. While there is an extensive literature on the effects of climate change on water resources, the uncertainty of climate change predictions continues to be high. This hinders the value of these predictions for municipal water supply planning. The ability of water utilities to meet future water needs will largely depend on their capacity to make decisions under uncertainty. Water stressors, like changes in demographics, climate, and socioeconomic patterns, have varying degrees of uncertainty. Identifying which stressors will have a greater impact on water resources, may reduce the level of future uncertainty for planning and managing water utilities. Within this context, we analyze historical and projected changes of population and climate to quantify the relative impacts of these two stressors on water resources. We focus on megacities that rely primarily on surface water resources to evaluate (a) population growth pattern from 1950-2010 and projected population for 2010-2060; (b) climate change impact on projected climate change scenarios for 2010-2060; and (c) water access for 1950-2010; projected needs for 2010-2060.

  4. Monitoring agricultural crop growth: comparison of high spatial-temporal satellite imagery versus UAV-based imaging spectrometer time series measurements

    Science.gov (United States)

    Mucher, Sander; Roerink, Gerbert; Franke, Jappe; Suomalainen, Juha; Kooistra, Lammert

    2014-05-01

    providers are involved in the consortium. First results show that the Greenmonitor is much more suitable for comparison in growth between fields at regional scale, while UAV based imagery is much more suitable for mapping variation in crop biochemistry (i.e., chlorophyll, nitrogen) within the fields, which requires in the Netherlands a spatial resolution of a few meters. Finally, the spatial and spectral dimension of satellite and UAV derived vegetation indices (i.e., weighted difference vegetation index, chlorophyll red-edge index) to evaluate to which extent UAV based image acquisition could be adopted to complement missing data in satellite time-series.

  5. Urban Land Cover Change Modelling Using Time-Series Satellite Images: A Case Study of Urban Growth in Five Cities of Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Abdullah F. Alqurashi

    2016-10-01

    Full Text Available This study analyses the expansion of urban growth and land cover changes in five Saudi Arabian cities (Riyadh, Jeddah, Makkah, Al-Taif and the Eastern Area using Landsat images for the 1985, 1990, 2000, 2007 and 2014 time periods. The classification was carried out using object-based image analysis (OBIA to create land cover maps. The classified images were used to predict the land cover changes and urban growth for 2024 and 2034. The simulation model integrated the Markov chain (MC and Cellular Automata (CA modelling methods and the simulated maps were compared and validated to the reference maps. The simulation results indicated high accuracy of the MC–CA integrated models. The total agreement between the simulated and the reference maps was >92% for all the simulation years. The results indicated that all five cities showed a massive urban growth between 1985 and 2014 and the predicted results showed that urban expansion is likely to continue going for 2024 and 2034 periods. The transition probabilities of land cover, such as vegetation and water, are most likely to be urban areas, first through conversion to bare soil and then to urban land use. Integrating of time-series satellite images and the MC–CA models provides a better understanding of the past, current and future patterns of land cover changes and urban growth in this region. Simulation of urban growth will help planners to develop sustainable expansion policies that may reduce the future environmental impacts.

  6. Water scarcity in the tropical Andes: population growth outweighs climate change

    Science.gov (United States)

    Buytaert, W.; De Bièvre, B.

    2012-12-01

    Globally, water resources for cities are under increasing stress. Two main stressors are climate change and population growth, but evaluating their relative impact is difficult, especially because of the complex topology of water supply. This is especially true in the tropical Andes, which is a region with strong climatic gradients and topographical limits to water resources. In this study we present an evaluation of both stressors on water resources in a geospatial framework to identify gradients in water availability that may lead to conflicts over water use. We focus on 4 major cities in, or receiving water from the tropical Andes. A multi-model dataset of 19 climate models is used as input for a regional water balance model. Per capita water availability is evaluated along topographic gradients for the present, and for future scenarios of population growth and climate change. In all cases, the median projection of climate change suggests a relatively limited impact on water availability but uncertainties are large. Despite these uncertainties, we find that the expected demographic changes are very likely to outpace the impact of climate change on water availability and should therefore be the priority for local policy making. However, distinctive geospatial patterns characterize the supply systems of the studied cities, highlighting the need to analyse the topology of water supply within an ecosystem services context. Our approach is flexible enough to be extended to other regions, stressors and water resources topologies.

  7. Bond population analysis on combination of favorable growth unit of Al(OH)3 crystals

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The quantum chemical calculation on four representative combination modes of the favorable growth unit Al6(OH)18(H2O)6of Al(OH)3 crystals and the single unit were calculated. On the base of the prior investigation, and from the point of view of bond population and net atomic charge, the relationships between the combination mode of the favorable growth unit and the relative intensity of chemical bond of the systems were discussed. The quantum chemistry calculations were performed at RB3LYP/6-31G and RHF/6-31G levels by ab initio and DFT methods respectively. From the point of view of bond population, it can be preliminarily presumed that the interatomic bond force of the system with side-face-combination-B mode is weaker to a certain extent. From the point of view of the net charge, when the combination mode is obverse-face-combination-D, the interatomic bond force will be enhanced.

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

    Directory of Open Access Journals (Sweden)

    Sam M. Ferreira

    2017-01-01

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    DeGrandi-Hoffman, Gloria; Ahumada, Fabiana; Zazueta, Victor; Chambers, Mona; Hidalgo, Geoffrey; deJong, Emily Watkins

    2016-05-01

    Varroa mites are a serious pest of honey bees and the leading cause of colony losses. Varroa have relatively low reproductive rates, so populations should not increase rapidly, but often they do. Other factors might contribute to the growth of varroa populations including mite migration into colonies on foragers from other hives. We measured the proportion of foragers carrying mites on their bodies while entering and leaving hives, and determined its relationship to the growth of varroa populations in those hives at two apiary sites. We also compared the estimates of mite population growth with predictions from a varroa population dynamics model that generates estimates of mite population growth based on mite reproduction. Samples of capped brood and adult bees indicated that the proportion of brood cells infested with mites and adult bees with phoretic mites was low through the summer but increased sharply in the fall especially at site 1. The frequency of capturing foragers with mites on their bodies while entering or leaving hives also increased in the fall. The growth of varroa populations at both sites was not significantly related to our colony estimates of successful mite reproduction, but instead to the total number of foragers with mites (entering and leaving the colony). There were more foragers with mites at site 1 than site 2, and mite populations at site 1 were larger especially in the fall. The model accurately estimated phoretic mite populations and infested brood cells until November when predictions were much lower than those measured in colonies. The rapid growth of mite populations particularly in the fall being a product of mite migration rather than mite reproduction only is discussed.

  11. Some socio-economic aspects of population growth in the USSR.

    Science.gov (United States)

    Simchera, V

    1974-01-01

    This summarizes population trends in the U.S.S.R. since the early 19 00's. On August 9, 1973, the population topped 250 million, almost precisely double that of Russia at the time of the 1st general census in 1897. Since 1922 it had increased by more than 84%. Russia has suffered more population loss in wars than any other country in modern times. The First World War, the Civil War, and the Second World War took a toll of more than 30 million, more than 20 million during the Second World War alone. The extent of these loses can be judged from the following: between 1897 and 1913 the population of Russia increased at the rate of 1.55% per annum or 34.6 million; if this had continued the population would have been at least 182.8 million by the end of 1922. As it was, the population was 136.1 million by 1922 and the hypothetical 182.8 million was not reached until 1952. More than 4/5 of today's population have been born since the October Revolution. Only 43 million were born before the revolution and only 7.5 were born in the last century. The economic base has grown much more rapidly than the population. For the period 1940-1972 the population increased 1.27 times, national income 9.51 times, fixed assets, 8.76 times, industrial production, 13.65 times, agricultural output, 2.14 times, and capital investment 14.52 times. The birthrate has been falling since World War 1 but total population growth has increased steadily. Birthrates have declined from 45.5/1000 in 1913 to 17.8/1000 in 1972 and a slight upturn is seen. It is expected that the birthrate will continue to increase slightly, then stabilize. Much of the population increase has come from significantly reduced mortality rates. 1st and 2nd children now account for 71% of all births. Family allowances, child care, free health care, and other social benefits encourage births while high employment levels for women, a shortage of men in the marriageable age ranges, and late marriages tend to depress the birthrate

  12. Stimulation with monochromatic green light during incubation alters satellite cell mitotic activity and gene expression in relation to embryonic and posthatch muscle growth of broiler chickens.

    Science.gov (United States)

    Zhang, L; Zhang, H J; Wang, J; Wu, S G; Qiao, X; Yue, H Y; Yao, J H; Qi, G H

    2014-01-01

    Previous studies showed that monochromatic green light stimuli during embryogenesis accelerated posthatch body weight (BW) and pectoral muscle growth of broilers. In this experiment, we further investigated the morphological and molecular basis of this phenomenon. Fertile broiler eggs (Arbor Acres, n=880) were pre-weighed and randomly assigned to 1 of the 2 incubation treatment groups: (1) dark condition (control group), and (2) monochromatic green light group (560 nm). The monochromatic lighting systems sourced from light-emitting diode lamps and were equalized at the intensity of 15 lx at eggshell level. The dark condition was set as a commercial control from day 1 until hatching. After hatch, 120 male 1-day-old chicks from each group were housed under incandescent white light with an intensity of 30 lx at bird-head level. No effects of light stimuli during embryogenesis on hatching time, hatchability, hatching weight and bird mortality during the feeding trial period were observed in the present study. Compared with the dark condition, the BW, pectoral muscle weight and myofiber cross-sectional areas were significantly greater on 7-day-old chicks incubated under green light. Green light also increased the satellite cell mitotic activity of pectoral muscle on 1- and 3-day-old birds. In addition, green light upregulated MyoD, myogenin and myostatin mRNA expression in late embryos and/ or newly hatched chicks. These data suggest that stimulation with monochromatic green light during incubation promote muscle growth by enhancing proliferation and differentiation of satellite cells in late embryonic and newly hatched stages. Higher expression of myostatin may ultimately help prevent excessive proliferation and differentiation of satellite cells in birds incubated under green light.

  13. Association of STAT2 SNP genotypes and growth phenotypes in heifers from an Angus, Brahman and Romosinuano diallel population

    Science.gov (United States)

    Components of the growth endocrine axis regulate growth and reproduction traits in cattle. A SNP in the promoter of the signal transducer and activator of transcription 2 (STAT2) has been previously reported to be associated with postpartum rebreeding in a diallel beef population composed of 650 hei...

  14. Identification of QTLs for shoot and root growth under ionic-osmotic stress in Lotus, using a RIL population

    DEFF Research Database (Denmark)

    Quero, Gastón; Gutíerrez, Lucía; Lascano, Ramiro

    2014-01-01

    The genus Lotus includes a group of forage legume species including genotypes of agronomic interest and model species. In this work, an experimental hydroponic growth system allowed the discrimination of growth responses to ionic-osmotic stress in a population of recombinant inbred lines (RILs) d...

  15. Identification of QTLs for shoot and root growth under ionic-osmotic stress in Lotus, using a RIL population

    DEFF Research Database (Denmark)

    Quero, Gastón; Gutíerrez, Lucía; Lascano, Ramiro

    2014-01-01

    The genus Lotus includes a group of forage legume species including genotypes of agronomic interest and model species. In this work, an experimental hydroponic growth system allowed the discrimination of growth responses to ionic-osmotic stress in a population of recombinant inbred lines (RILs...

  16. Population dynamics of Gluconacetobacter diazotrophicus in sugarcane cultivars and its effect on plant growth.

    Science.gov (United States)

    Muñoz-Rojas, J; Caballero-Mellado, J

    2003-11-01

    Different experiments have estimated that the contribution of biological nitrogen fixation (BNF) is largely variable among sugarcane cultivars. Which bacteria are the most important in sugarcane-associated BNF is unknown. However, Gluconacetobacter diazotrophicus has been suggested as a strong candidate responsible for the BNF observed. In the present study, bacteria-free micropropagated plantlets of five sugarcane cultivars were inoculated with three G. diazotrophicus strains belonging to different genotypes. Bacterial colonization was monitored under different nitrogen fertilization levels and at different stages of plant growth. Analysis of the population dynamics of G. diazotrophicus strains in the different sugarcane varieties showed that the bacterial populations decreased drastically in relation to plant age, regardless of the nitrogen fertilization level, bacterial genotype or sugarcane cultivars. However, the persistence of the three strains was significantly longer in some cultivars (e.g., MEX 57-473) than in others (e.g., MY 55-14). In addition, some strains (e.g., PAl 5(T)) persisted for longer periods in higher numbers than other strains (e.g., PAl 3) inside plants of all the cultivars tested. Indeed, the study showed that the inoculation of G. diazotrophicus may be beneficial for sugarcane plant growth, but this response is dependent both on the G. diazotrophicus genotype and the sugarcane variety. The most positive response to inoculation was observed with the combination of strain PAl 5(T) and the variety MEX 57-473. Although the positive effect on sugarcane growth apparently occurred by mechanisms other than nitrogen fixation, the results show the importance of the sugarcane variety for the persistence of the plant-bacteria interaction, and it could explain the different rates of BNF estimated among sugarcane cultivars.

  17. Morphometry, growth and reproduction of an Atlantic population of the razor clam Ensis macha (Molina, 1782

    Directory of Open Access Journals (Sweden)

    Pedro J. Barón

    2004-06-01

    Full Text Available Ensis macha is a razor clam distributed throughout the coasts of southern Argentina and Chile. Even though it represents a valuable fishery resource, the exploitation of its Atlantic populations has begun only in recent years. This study provides the first estimates of growth rate, an interpretation of the reproductive cycle on the coast of the northern Argentine Patagonia and an analysis of the species morphometry. Growth was estimated by direct observation of growth rings on the valves by two observers. The reproductive cycle was interpreted by the analysis of temporal change of oocyte size frequency distributions. Parameter estimations for the von Bertalanffy equations respectively obtained by observers 1 and 2 were 154 and 153.7 mm for L?, 0.25 and 0.20 yr-1 for k, and -0.08 and -0.72 yr for t0. Two spawning peaks were detected: September-November 1999 and May-June 2000. However, mature females were found all year round. An abrupt change in the relationship between shell length and height was detected at 11.2 mm length.

  18. Fracture and Growth Are Competing Forces Determining the Fate of Conformers in Tau Fibril Populations*

    Science.gov (United States)

    Meyer, Virginia; Holden, Michael R.; Weismiller, Hilary A.; Eaton, Gareth R.; Eaton, Sandra S.; Margittai, Martin

    2016-01-01

    Tau fibrils are pathological aggregates that can transfer between neurons and then recruit soluble Tau monomers by template-assisted conversion. The propagation of different fibril polymorphs is thought to be a contributing factor to phenotypic diversity in Alzheimer disease and other Tauopathies. We found that a homogeneous population of Tau fibrils composed of the truncated version K18 (residues 244–372) gradually converted to a new set of fibril conformers when subjected to multiple cycles of seeding and growth. Using double electron-electron resonance (DEER) spectroscopy, we observed that the distances between spin labels at positions 311 and 328 in the fibril core progressively decreased. The findings were corroborated by changes in turbidity, morphology, and protease sensitivity. Fibrils that were initially formed under stirring conditions exhibited an increased fragility compared with fibrils formed quiescently after multiple cycles of seeding. The quiescently formed fibrils were marked by accelerated growth. The difference in fragility and growth between the different conformers explains how the change in incubation condition could lead to the amplification of a minor subpopulation of fibrils. Under quiescent conditions where fibril breakage is minimal, faster growing fibrils have a selective advantage. The findings are of general importance as they suggest that changes in selective pressures during fibril propagation in the human brain could result in the emergence of new fibril conformers with varied clinicopathological consequences. PMID:27080260

  19. Fracture and Growth Are Competing Forces Determining the Fate of Conformers in Tau Fibril Populations.

    Science.gov (United States)

    Meyer, Virginia; Holden, Michael R; Weismiller, Hilary A; Eaton, Gareth R; Eaton, Sandra S; Margittai, Martin

    2016-06-03

    Tau fibrils are pathological aggregates that can transfer between neurons and then recruit soluble Tau monomers by template-assisted conversion. The propagation of different fibril polymorphs is thought to be a contributing factor to phenotypic diversity in Alzheimer disease and other Tauopathies. We found that a homogeneous population of Tau fibrils composed of the truncated version K18 (residues 244-372) gradually converted to a new set of fibril conformers when subjected to multiple cycles of seeding and growth. Using double electron-electron resonance (DEER) spectroscopy, we observed that the distances between spin labels at positions 311 and 328 in the fibril core progressively decreased. The findings were corroborated by changes in turbidity, morphology, and protease sensitivity. Fibrils that were initially formed under stirring conditions exhibited an increased fragility compared with fibrils formed quiescently after multiple cycles of seeding. The quiescently formed fibrils were marked by accelerated growth. The difference in fragility and growth between the different conformers explains how the change in incubation condition could lead to the amplification of a minor subpopulation of fibrils. Under quiescent conditions where fibril breakage is minimal, faster growing fibrils have a selective advantage. The findings are of general importance as they suggest that changes in selective pressures during fibril propagation in the human brain could result in the emergence of new fibril conformers with varied clinicopathological consequences. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. Growth and Reproduction of Glyphosate-Resistant and Susceptible Populations of Kochia scoparia.

    Science.gov (United States)

    Kumar, Vipan; Jha, Prashant

    2015-01-01

    Evolution of glyphosate-resistant kochia is a threat to no-till wheat-fallow and glyphosate-resistant (GR) cropping systems of the US Great Plains. The EPSPS (5-enol-pyruvylshikimate-3-phosphate synthase) gene amplification confers glyphosate resistance in the tested Kochia scoparia (L.) Schrad populations from Montana. Experiments were conducted in spring to fall 2014 (run 1) and summer 2014 to spring 2015 (run 2) to investigate the growth and reproductive traits of the GR vs. glyphosate-susceptible (SUS) populations of K. scoparia and to determine the relationship of EPSPS gene amplification with the level of glyphosate resistance. GR K. scoparia inbred lines (CHES01 and JOP01) exhibited 2 to 14 relative copies of the EPSPS gene compared with the SUS inbred line with only one copy. In the absence of glyphosate, no differences in growth and reproductive parameters were evident between the tested GR and SUS inbred lines, across an intraspecific competition gradient (1 to 170 plants m-2). GR K. scoparia plants with 2 to 4 copies of the EPSPS gene survived the field-use rate (870 g ha-1) of glyphosate, but failed to survive the 4,350 g ha-1 rate of glyphosate (five-times the field-use rate). In contrast, GR plants with 5 to 14 EPSPS gene copies survived the 4,350 g ha-1 of glyphosate. The results from this research indicate that GR K. scoparia with 5 or more EPSPS gene copies will most likely persist in field populations, irrespective of glyphosate selection pressure.

  1. Growth and Reproduction of Glyphosate-Resistant and Susceptible Populations of Kochia scoparia.

    Directory of Open Access Journals (Sweden)

    Vipan Kumar

    Full Text Available Evolution of glyphosate-resistant kochia is a threat to no-till wheat-fallow and glyphosate-resistant (GR cropping systems of the US Great Plains. The EPSPS (5-enol-pyruvylshikimate-3-phosphate synthase gene amplification confers glyphosate resistance in the tested Kochia scoparia (L. Schrad populations from Montana. Experiments were conducted in spring to fall 2014 (run 1 and summer 2014 to spring 2015 (run 2 to investigate the growth and reproductive traits of the GR vs. glyphosate-susceptible (SUS populations of K. scoparia and to determine the relationship of EPSPS gene amplification with the level of glyphosate resistance. GR K. scoparia inbred lines (CHES01 and JOP01 exhibited 2 to 14 relative copies of the EPSPS gene compared with the SUS inbred line with only one copy. In the absence of glyphosate, no differences in growth and reproductive parameters were evident between the tested GR and SUS inbred lines, across an intraspecific competition gradient (1 to 170 plants m-2. GR K. scoparia plants with 2 to 4 copies of the EPSPS gene survived the field-use rate (870 g ha-1 of glyphosate, but failed to survive the 4,350 g ha-1 rate of glyphosate (five-times the field-use rate. In contrast, GR plants with 5 to 14 EPSPS gene copies survived the 4,350 g ha-1 of glyphosate. The results from this research indicate that GR K. scoparia with 5 or more EPSPS gene copies will most likely persist in field populations, irrespective of glyphosate selection pressure.

  2. Components and public health impact of population growth in the Arab world.

    Directory of Open Access Journals (Sweden)

    Asharaf Abdul Salam

    Full Text Available The Arab world, which consists of the 22 member states of the Arab League, is undergoing a rapid transition in demographics, including fertility, mortality, and migration. Comprising a distinctive geographic region spread across West Asia and North East Africa and unified by the Arabic language, these states share common values and characteristics despite having diverse economic and political conditions. The demographic lag (high fertility and low mortality that characterizes the Arab world is unique, but the present trend of declining fertility, combined with the relatively low mortality, brings about significant changes in its population size. This research aimed to: (i assess the population growth in the Arab world over 3 time periods, (ii explore its components, and (iii understand its public health impact. Data from the International Data Base (IDB of the U.S. Census Bureau for 3 time periods (1992, 2002, and 2012 in 21 countries of the Arab world were analyzed by dividing them into four geographic sectors, namely, the Gulf Cooperation Council (GCC, West Asia, Maghreb, and the Nile Valley African Horn. The population of the Arab world has grown considerably due to both natural growth and migration. The immigration is pronounced, especially into resource-intensive GCC nations, not only from East Asian and Central African countries but also from resource-thrifty (limited-resource Arab nations. The migrations within, as well as outside, the Arab world reveal an interesting demographic phenomenon that requires further research: migration flows and trends. However, the transformations in public health statistics related to mortality-the impact of demographic changes-depict a new era in the Arab world.

  3. Components and public health impact of population growth in the Arab world.

    Science.gov (United States)

    Abdul Salam, Asharaf; Elsegaey, Ibrahim; Khraif, Rshood; AlMutairi, Abdullah; Aldosari, Ali

    2015-01-01

    The Arab world, which consists of the 22 member states of the Arab League, is undergoing a rapid transition in demographics, including fertility, mortality, and migration. Comprising a distinctive geographic region spread across West Asia and North East Africa and unified by the Arabic language, these states share common values and characteristics despite having diverse economic and political conditions. The demographic lag (high fertility and low mortality) that characterizes the Arab world is unique, but the present trend of declining fertility, combined with the relatively low mortality, brings about significant changes in its population size. This research aimed to: (i) assess the population growth in the Arab world over 3 time periods, (ii) explore its components, and (iii) understand its public health impact. Data from the International Data Base (IDB) of the U.S. Census Bureau for 3 time periods (1992, 2002, and 2012) in 21 countries of the Arab world were analyzed by dividing them into four geographic sectors, namely, the Gulf Cooperation Council (GCC), West Asia, Maghreb, and the Nile Valley African Horn. The population of the Arab world has grown considerably due to both natural growth and migration. The immigration is pronounced, especially into resource-intensive GCC nations, not only from East Asian and Central African countries but also from resource-thrifty (limited-resource) Arab nations. The migrations within, as well as outside, the Arab world reveal an interesting demographic phenomenon that requires further research: migration flows and trends. However, the transformations in public health statistics related to mortality-the impact of demographic changes-depict a new era in the Arab world.

  4. Cell Differentiation in a Bacillus thuringiensis Population during Planktonic Growth, Biofilm Formation, and Host Infection

    Science.gov (United States)

    Verplaetse, Emilie; Slamti, Leyla; Gohar, Michel

    2015-01-01

    ABSTRACT Bacillus thuringiensis (Bt) is armed to complete a full cycle in its insect host. During infection, virulence factors are expressed under the control of the quorum sensor PlcR to kill the host. After the host’s death, the quorum sensor NprR controls a necrotrophic lifestyle, allowing the vegetative cells to use the insect cadaver as a bioincubator and to survive. Only a part of the Bt population sporulates in the insect cadaver, and the precise composition of the whole population and its evolution over time are unknown. Using fluorescent reporters to record gene expression at the single-cell level, we have determined the differentiation course of a Bt population and explored the lineage existing among virulent, necrotrophic, and sporulating cells. The dynamics of cell differentiation were monitored during growth in homogenized medium, biofilm formation, and colonization of insect larvae. We demonstrated that in the insect host and in planktonic culture in rich medium, the virulence, necrotrophism, and sporulation regulators are successively activated in the same cell. In contrast, in biofilms, activation of PlcR is dispensable for NprR activation and we observed a greater heterogeneity than under the other two growth conditions. We also showed that sporulating cells arise almost exclusively from necrotrophic cells. In biofilm and in the insect cadaver, we identified an as-yet-uncharacterized category of cells that do not express any of the reporters used. Overall, we showed that PlcR, NprR, and Spo0A act as interconnected integrators to allow finely tuned adaptation of the pathogen to its environment. PMID:25922389

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

    Science.gov (United States)

    Schwindt, Adam R; Winkelman, Dana L

    2016-09-01

    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.

  6. Reproduction, abundance, and population growth for a fisher (Pekania pennanti) population in the Sierra National Forest, California

    Science.gov (United States)

    Rick A. Sweitzer; Viorel D. Popescu; Reginald H. Barrett; Kathryn L. Purcell; Craig M. Thompson

    2015-01-01

    In the west coast region of the United States, fishers (Pekania pennanti) exist in 2 remnant populations—1 in northern California and 1 in the southern Sierra Nevada, California—and 3 reintroduced populations (western Washington, southern Oregon, and northeastern California). The West Coast Distinct Population Segment of fishers encompassing all of...

  7. World population and energy growth: Impact on the Caribbean and the roles of energy efficiency improvements and renewable energies

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, J.

    1997-06-01

    This paper briefly describes population and energy use trends and their consequences, particularly to the Caribbean region. Historical trends for transitional countries show a decrease in population growth rate as annual per capita commercial energy use increases. If trends continue, an increase in per capita energy will be important to stabilizing populations of transitional countries. Energy efficiency improvements, the role of fossil energy, and the use of alternative energy sources in Caribbean nations are briefly discussed. 6 refs., 3 figs.

  8. World population and energy growth: Impact on the Caribbean and the roles of energy efficiency improvements and renewable energies

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, J.

    1997-06-01

    This paper briefly describes population and energy use trends and their consequences, particularly to the Caribbean region. Historical trends for transitional countries show a decrease in population growth rate as annual per capita commercial energy use increases. If trends continue, an increase in per capita energy will be important to stabilizing populations of transitional countries. Energy efficiency improvements, the role of fossil energy, and the use of alternative energy sources in Caribbean nations are briefly discussed. 6 refs., 3 figs.

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

    Science.gov (United States)

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

    2017-04-01

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

  10. A national system for monitoring the population of agricultural pests using an integrated approach of remote sensing data from in situ automated traps and satellite images

    Science.gov (United States)

    Diofantos, Hadjimitsis G.; Panayiotis, Philimis; Elias, Psimolophitis; Georgiou, George K.; Kyriacos, Themistocleous

    2010-10-01

    A national system for monitoring the population increase of agricultural pest "Lobesia Botrana" (vine moth/fly that attacks grapes) in Cyprus has been developed. The system comprises of automated delta traps with GPS that use wireless(Wi-Fi) camera, automated image analysis for identification of the specific fly species, Wi-Fi technology for transferring the data using mobile telephony network to a central station for result presentation and analysis. A GIS database was developed and included details of the pilot vineyards, environmental conditions and daily data of the number of captured flies from each automated trap. The results were compared with MODIS and LANDSAT satellite thermal images since the appearance of the vine fly is greatly dependent on the microclimate temperatures (degree days). Results showed that satellite data can estimate accurately the appearance of the vine fly. The proposed system can be an important tool for the improvement of a national Integrated Pest Management (IPM) system and it can also be used for monitoring other agricultural pests and insects.

  11. Inference of Super-exponential Human Population Growth via Efficient Computation of the Site Frequency Spectrum for Generalized Models.

    Science.gov (United States)

    Gao, Feng; Keinan, Alon

    2016-01-01

    The site frequency spectrum (SFS) and other genetic summary statistics are at the heart of many population genetic studies. Previous studies have shown that human populations have undergone a recent epoch of fast growth in effective population size. These studies assumed that growth is exponential, and the ensuing models leave an excess amount of extremely rare variants. This suggests that human populations might have experienced a recent growth with speed faster than exponential. Recent studies have introduced a generalized growth model where the growth speed can be faster or slower than exponential. However, only simulation approaches were available for obtaining summary statistics under such generalized models. In this study, we provide expressions to accurately and efficiently evaluate the SFS and other summary statistics under generalized models, which we further implement in a publicly available software. Investigating the power to infer deviation of growth from being exponential, we observed that adequate sample sizes facilitate accurate inference; e.g., a sample of 3000 individuals with the amount of data expected from exome sequencing allows observing and accurately estimating growth with speed deviating by ≥10% from that of exponential. Applying our inference framework to data from the NHLBI Exome Sequencing Project, we found that a model with a generalized growth epoch fits the observed SFS significantly better than the equivalent model with exponential growth (P-value [Formula: see text]). The estimated growth speed significantly deviates from exponential (P-value [Formula: see text]), with the best-fit estimate being of growth speed 12% faster than exponential.

  12. Field population abundance of leafhopper (Homoptera: Cicadelidae) and planthopper (Homoptera: Delphacidae) as affected by rice growth stages

    Science.gov (United States)

    Hafizal, M. M.; Idris, A. B.

    2013-11-01

    The leafhopper (Homoptera: Delphacidae) and planthopper (Homoptera: Cicadelidae) are considered as important rice pest in Asia including Malaysia. As phloem-feeders, they can cause loss to rice growth development and their population abundance is thought to be influenced by rice growth stages. This study was conducted to examine the population of Delphacidae and Cicadelidae between different rice growth stages, i.e. before and after rice planting periods. Monthly sampling was conducted in three sites in Kuala Selangor at before planting, vegetative, reproductive, maturing stages and post-harvest period using sweeping net and light traps. Population abundance of Delphacidae and Cicadelidae were found to be significantly different and positively correlated with different rice growth stages (ppopulation of these two homopterans indicated adaptive feeding strategy to reduce food competition.

  13. Structure, growth and secondary production of two Tyrrhenian populations of the white gorgonian Eunicella singularis (Esper 1791)

    Science.gov (United States)

    Munari, Cristina; Serafin, Greta; Mistri, Michele

    2013-03-01

    Growth and secondary production of the shallow-water gorgonian Eunicella singularis were investigated at two infralittoral rocky stations located in the Tyrrhenian Sea (Cannitello and Cape Enfola), separated by a cline of 4° latitude. Colonies were aged by counting the number of annual growth rings at the base of the skeleton. Mean annual linear growth rates were calculated by fitting a von Bertalanffy growth equation for the species. Growth rates were 3.55 and 4.52 cm yr-1 respectively. The Enfola population exhibited an age structure reflecting a past pulse in recruitment. The Cannitello population exhibited a gamma-type distribution, dominated by younger age classes, thus suggesting a continuous recruitment rate over time. The two population differed also in colony density, which was higher at Enfola. Secondary production was estimated by means of the increment-summation method, and yielded 5.6 and 3.2 g ash-free dry weight (AFDW) m-2 yr-1 for Cannitello and Enfola populations, respectively. P/B ratio was higher at Cannitello, because of the age structure of the population. Strong currents probably cause population density-thinning mechanisms, favoring a more continuous recruitment.

  14. Rate and time trend of perinatal, infant, maternal mortality, natality and natural population growth in kosovo.

    Science.gov (United States)

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

    2012-01-01

    THE AIM OF WORK HAS BEEN THE PRESENTATION OF THE RATE AND TIME TRENDS OF SOME INDICATORS OF THE HEATH CONDITION OF MOTHERS AND CHILDREN IN KOSOVO: fetal mortality, early neonatal mortality, perinatal mortality, infant mortality, natality, natural growth of population etc. The treated patients were the newborn and infants in the post neonatal period, women during their pregnancy and those 42 days before and after the delivery. THE DATA WERE TAKEN FROM: register of the patients treated in the Pediatric Clinic of Prishtina, World Health Organization, Mother and Child Health Care, Reproductive Health Care, Ministry of Health of the Republic of Kosovo, Statistical Department of Kosovo, the National Institute of Public Health and several academic texts in the field of pediatrics. Some indicators were analyzed in a period between year 1945-2010 and 1950-2010, whereas some others were analyzed in a time period between year 2000 and 2011. The perinatal mortality rate in 2000 was 29.1‰, whereas in 2011 it was 18.7‰. The fetal mortality rate was 14.5‰ during the year 2000, whereas in 2011 it was 11.0‰, in 2000 the early neonatal mortality was 14.8‰, in 2011 it was 7.5‰. The infant mortality in Kosovo was 164‰ in 1950, whereas in 2010 it was 20.5‰. The most frequent causes of infant mortality have been: lower respiratory tract infections, acute infective diarrhea, perinatal causes, congenital malformations and unclassified conditions. Maternal death rate varied during this time period. Maternal death in 2000 was 23 whereas in 2010 only two cases were reported. Regarding the natality, in 1950 it reached 46.1 ‰, whereas in 2010 it reached 14‰, natural growth of population rate in Kosovo was 29.1‰ in 1950, whereas in 2011 it was 11.0‰. Perinatal mortality rate in Kosovo is still high in comparison with other European countries (Turkey and Kyrgyzstan have the highest perinatal mortality rate), even though it is in a continuous decrease. Infant mortality

  15. GROWTH OF STREPTOCOCCUS MUTANS IN BIOFILMS ALTERS PEPTIDE SIGNALING AT THE SUB-POPULATION LEVEL

    Directory of Open Access Journals (Sweden)

    Robert Colquhoun Shields

    2016-07-01

    Full Text Available Streptococcus mutans activates multiple cellular processes in response to the formation of a complex between comX-inducing peptide (XIP and the ComR transcriptional regulator. Bulk phase and microfluidic experiments previously revealed that ComR-dependent activation of comX is altered by pH and by carbohydrate source. Biofilm formation is a major factor in bacterial survival and virulence in the oral cavity. Here, we sought to determine the response of S. mutans biofilm cells to XIP during different stages of biofilm maturation. Using flow cytometry and confocal microscopy, we showed that exogenous addition of XIP to early biofilms resulted in robust comX activation. However, as the biofilms matured, increasing amounts of XIP were required to activate comX expression. Single-cell analysis demonstrated that the entire population was responding to XIP with activation of comX in early biofilms, but only a sub-population was responding in mature biofilms. The sub-population response of mature biofilms was retained when the cells were dispersed and then treated with XIP. The proportion and intensity of the bi-modal response of mature biofilm cells was altered in mutants lacking the Type II toxins MazF and RelE, or in a strain lacking the (pppGpp synthase/hydrolase RelA. Thus, competence signaling is markedly altered in cells growing in mature biofilms, and pathways that control cell death and growth/survival decisions modulate activation of comX expression in these sessile populations.

  16. Growth of Streptococcus mutans in Biofilms Alters Peptide Signaling at the Sub-population Level

    Science.gov (United States)

    Shields, Robert C.; Burne, Robert A.

    2016-01-01

    Streptococcus mutans activates multiple cellular processes in response to the formation of a complex between comX-inducing peptide (XIP) and the ComR transcriptional regulator. Bulk phase and microfluidic experiments previously revealed that ComR-dependent activation of comX is altered by pH and by carbohydrate source. Biofilm formation is a major factor in bacterial survival and virulence in the oral cavity. Here, we sought to determine the response of S. mutans biofilm cells to XIP during different stages of biofilm maturation. Using flow cytometry and confocal microscopy, we showed that exogenous addition of XIP to early biofilms resulted in robust comX activation. However, as the biofilms matured, increasing amounts of XIP were required to activate comX expression. Single-cell analysis demonstrated that the entire population was responding to XIP with activation of comX in early biofilms, but only a sub-population was responding in mature biofilms. The sub-population response of mature biofilms was retained when the cells were dispersed and then treated with XIP. The proportion and intensity of the bi-modal response of mature biofilm cells was altered in mutants lacking the Type II toxins MazF and RelE, or in a strain lacking the (p)ppGpp synthase/hydrolase RelA. Thus, competence signaling is markedly altered in cells growing in mature biofilms, and pathways that control cell death and growth/survival decisions modulate activation of comX expression in these sessile populations. PMID:27471495

  17. Cassini Growth of Population Between Two Metropolitan Cities——A Case Study of Beijing-Tianjin Region, China

    Institute of Scientific and Technical Information of China (English)

    ZONG Yueguang; YANG Wei; MA Qiang; XUE Song

    2009-01-01

    The existing models of population distribution often focus on the region with a single city or even multiple centers, and lack the detailed explorations of the common and special type of urbanization areas with two centers. Taking Beijing-Tianjin region of China, which is a distinct dual-nuclei metropolitan area in the world, as an example and choosing Landsat-5 TM image in 2005, population, etc. As the data, this paper devotes to comprehending and illus-trating a model of Cassini growth of population between the two metropolitan cities through the research of spatial population distribution pattern, aided with RS and GIS techniques. Main technical processes include Kriging interpola-tion of the population data and character simulation of the Cassini ovals. According to the calculation of a/b, a key characteristic index of Cassini growth model, the spatial structures of population distribution were given. When a/b1,it is a curve with two separated loops with a population density more than 3000 persons/km2. When a/b=1, it is a lem-niscate curve with a population density about 3000 persons/km2. When 1(√2), there is an oval-shaped convex curve with a population density less than 500 persons/km2. The results show that owing to the combined action and influence of the regional dual-nuclei, the population distribution of Beijing-Tianjin region is in accord with Cassini model significantly. There-fore, there is Cassini growth of population between the two metropolitan cities in Beijing-Tianjin region. In addition,the process of Cassini growth has extraordinarily instructive significance for judging the development stages of the dual-nuclei metropolitan areas.

  18. Richards growth model and viability indicators for populations subject to interventions

    Directory of Open Access Journals (Sweden)

    Selene Loibel

    2010-12-01

    Full Text Available In this work we study the problem of modeling identification of a population employing a discrete dynamic model based on the Richards growth model. The population is subjected to interventions due to consumption, such as hunting or farming animals. The model identification allows us to estimate the probability or the average time for a population number to reach a certain level. The parameter inference for these models are obtained with the use of the likelihood profile technique as developed in this paper. The identification method here developed can be applied to evaluate the productivity of animal husbandry or to evaluate the risk of extinction of autochthon populations. It is applied to data of the Brazilian beef cattle herd population, and the the population number to reach a certain goal level is investigated.Neste trabalho estudamos o problema de identificação do modelo de uma população utilizando um modelo dinâmico discreto baseado no modelo de crescimento de Richards. A população é submetida a intervenções devido ao consumo, como no caso de caça ou na criação de animais. A identificação do modelo permite-nos estimar a probabilidade ou o tempo médio de ocorrência para que se atinja um certo número populacional. A inferência paramétrica dos modelos é obtida através da técnica de perfil de máxima verossimilhança como desenvolvida neste trabalho. O método de identificação desenvolvido pode ser aplicado para avaliar a produtividade de criação animal ou o risco de extinção de uma população autóctone. Ele foi aplicado aos dados da população global de gado de corte bovino brasileiro, e é utilizado na investigação de a população atingir um certo número desejado de cabeças.

  19. Modelagem do crescimento populacional do rebanho bovino brasileiro Modeling the growth of Brazilian cattle population

    Directory of Open Access Journals (Sweden)

    Alfredo Ribeiro de Freitas

    2005-12-01

    Full Text Available Considerando-se o número efetivo de animais e a taxa de abate do rebanho bovino brasileiro no período de 1983 a 2000, estimou-se o crescimento dessa população utilizando-se o modelo de Richards, ajustado pela técnica de verossimilhança profile. O modelo se mostrou adequado para descrever o crescimento da população brasileira de bovinos, pois as superestimavas e ou subestimavas dos valores se situaram entre 1 e 2,5%. A partir da modelagem por cadeia de Markov, foram calculados a probabilidade de o rebanho atingir 200 milhões de animais até o ano de 2015, em função da taxa de abate, e o tempo esperado para se atingir este tamanho populacional, em função da taxa de abate. A probabilidade de o rebanho atingir 200 milhões de animais até o ano de 2015, a uma taxa de abate de aproximadamente 17%, é 0,7. Com taxa de abate anual de 16%, o rebanho atingirá esse tamanho no período de 11 anos e, com taxa de abate de 18%, em 20 anos.The growth of the Brazilian bovine cattle population was evaluated using the effective number of animals and the annual slaughter rate from 1983 to 2000. The Richards model was fitted with the profile likelihood technique. Two population parameters were calculated by Markov chain modeling: a the probability of the cattle population to reach 200 million of animals in 2015 as a function of the slaughter rate; b the time to reach this size, considering different annual slaughter rates. The Richards model was adequate to estimate the Brazilian cattle population growth since overestimated and/or underestimated values ranged between one and 2.5%. The probability of the Brazilian herd to reach 200 millions animals in 2015 for an annual slaughter rate of approximately 17% is 0.7 and the expected time to reach 200 million animals for annual slaughter rates of 16% and 18% was 11 and 20 years respectively.

  20. Feeding the world's increasing population while limiting climate change impacts; decoupling agriculture' s N2O and CH4 emissions from population growth

    NARCIS (Netherlands)

    Beek, C.L.; Meerburg, B.G.; Schils, R.L.M.; Verhagen, J.; Kuikman, P.J.

    2010-01-01

    The global demand for agricultural products, including food, is rapidly increasing due to population growth and shifts in consumption patterns. The required increase in agricultural production is predominantly to be achieved in countries with relatively low agricultural production levels at present.

  1. Narrow-front loop migration in a population of the common cuckoo Cuculus canorus, as revealed by satellite telemetry.

    Science.gov (United States)

    Willemoes, Mikkel; Strandberg, Roine; Klaassen, Raymond H G; Tøttrup, Anders P; Vardanis, Yannis; Howey, Paul W; Thorup, Kasper; Wikelski, Martin; Alerstam, Thomas

    2014-01-01

    Narrow migration corridors known in diurnal, social migrants such as raptors, storks and geese are thought to be caused by topographical leading line effects in combination with learning detailed routes across generations. Here, we document narrow-front migration in a nocturnal, solitary migrant, the common cuckoo Cuculus canorus, using satellite telemetry. We tracked the migration of adult cuckoos from the breeding grounds in southern Scandinavia (n = 8), to wintering sites in south-western Central Africa (n = 6) and back to the breeding grounds (n = 3). Migration patterns were very complex; in addition to the breeding and wintering sites, six different stopover sites were identified during the 16,000 km annual route that formed a large-scale clockwise loop. Despite this complexity, individuals showed surprisingly similar migration patterns, with very little variation between routes. We compared observed tracks with simulated routes based on vector orientation (with and without effects of barriers on orientation and survival). Observed distances between routes were often significantly smaller than expected if the routes were established on the basis of an innate vector orientation programme. Average distance between individuals in eastern Sahel after having migrated more than 5,000 km for example, was merely 164 km. This implies that more sophisticated inherent guiding mechanisms, possibly involving elements of intermediate goal area navigation or more elaborate external cues, are necessary to explain the complex narrow-front migration pattern observed for the cuckoos in this study.

  2. Narrow-front loop migration in a population of the common cuckoo Cuculus canorus, as revealed by satellite telemetry.

    Directory of Open Access Journals (Sweden)

    Mikkel Willemoes

    Full Text Available Narrow migration corridors known in diurnal, social migrants such as raptors, storks and geese are thought to be caused by topographical leading line effects in combination with learning detailed routes across generations. Here, we document narrow-front migration in a nocturnal, solitary migrant, the common cuckoo Cuculus canorus, using satellite telemetry. We tracked the migration of adult cuckoos from the breeding grounds in southern Scandinavia (n = 8, to wintering sites in south-western Central Africa (n = 6 and back to the breeding grounds (n = 3. Migration patterns were very complex; in addition to the breeding and wintering sites, six different stopover sites were identified during the 16,000 km annual route that formed a large-scale clockwise loop. Despite this complexity, individuals showed surprisingly similar migration patterns, with very little variation between routes. We compared observed tracks with simulated routes based on vector orientation (with and without effects of barriers on orientation and survival. Observed distances between routes were often significantly smaller than expected if the routes were established on the basis of an innate vector orientation programme. Average distance between individuals in eastern Sahel after having migrated more than 5,000 km for example, was merely 164 km. This implies that more sophisticated inherent guiding mechanisms, possibly involving elements of intermediate goal area navigation or more elaborate external cues, are necessary to explain the complex narrow-front migration pattern observed for the cuckoos in this study.

  3. The protective function of personal growth initiative among a genocide-affected population in Rwanda.

    Science.gov (United States)

    Blackie, Laura E R; Jayawickreme, Eranda; Forgeard, Marie J C; Jayawickreme, Nuwan

    2015-07-01

    The aim of the current study was to investigate the extent to which individual differences in personal growth initiative (PGI) were associated with lower reports of functional impairment of daily activities among a genocide-affected population in Rwanda. PGI measures an individual's motivation to develop as a person and the extent to which he or she is active in setting goals that work toward achieving self-improvement. We found that PGI was negatively associated with functional impairment when controlling for depression, posttraumatic stress disorder, and other demographic factors. Our results suggest that PGI may constitute an important mindset for facilitating adaptive functioning in the aftermath of adversity and in the midst of psychological distress, and as such they might have practical applications for the development of intervention programs. (c) 2015 APA, all rights reserved).

  4. The 'Natural Laboratory', a tool for deciphering growth, lifetime and population dynamics in larger benthic foraminifera

    Science.gov (United States)

    Hohenegger, Johann

    2015-04-01

    The shells of symbiont-bearing larger benthic Foraminifera (LBF) represent the response to physiological requirements in dependence of environmental conditions. All compartments of the shell such as chambers and chamberlets accommodate the growth of the cell protoplasm and are adaptations for housing photosymbiotic algae. Investigations on the biology of LBF were predominantly based on laboratory studies. The lifetime of LBF under natural conditions is still unclear. LBF, which can build >100 chambers during their lifetime, are thought to live at least one year under natural conditions. This is supported by studies on population dynamics of eulittoral foraminifera. In species characterized by a time-restricted single reproduction period the mean size of specimens increases from small to large during lifetime simultaneously reducing individual number. This becomes more complex when two or more reproduction times are present within a one-year cycle leading to a mixture of abundant small individuals with few large specimens during the year, while keeping mean size more or less constant. This mixture is typical for most sublittoral megalospheric (gamonts or schizonts) LBF. Nothing is known on the lifetime of agamonts, the diploid asexually reproducing generation. In all hyaline LBF it is thought to be significantly longer than 1 year based on the large size and considering the mean chamber building rate of the gamont/schizonts. Observations on LBF under natural conditions have not been performed yet in the deeper sublittoral. This reflects the difficulties due to intense hydrodynamics that hinder deploying technical equipment for studies in the natural environment. Therefore, studying growth, lifetime and reproduction of sublittoral LBF under natural conditions can be performed using the so-called 'natural laboratory' in comparison with laboratory investigations. The best sampling method in the upper sublittoral from 5 to 70 m depth is by SCUBA diving. Irregular

  5. L-cysteine-assisted growth of core-satellite ZnS-Au nanoassemblies with high photocatalytic efficiency.

    Science.gov (United States)

    Chen, Wei-Ta; Hsu, Yung-Jung

    2010-04-20

    Core-satellite ZnS-Au nanoassemblies, in which each of the ZnS nanospheres was surrounded by a few Au nanoparticles, have been successfully prepared with a facile L-cysteine-assisted hydrothermal approach. The density of Au nanoparticles encircling each ZnS nanosphere can be readily controlled through suitably modulating the concentration of Au added. Because of the difference in band structures between ZnS and Au, a pronounced photoinduced charge separation was observed for the as-synthesized ZnS-Au nanoassemblies. As compared to the relevant commercial products like Au-loaded P-25 TiO(2) and ZnS powders, ZnS-Au nanoassemblies exhibited superior photocatalytic performance, demonstrating their potential as an efficient photocatalyst in relevant redox reactions. Furthermore, the recycling test revealed that core-satellite nanoassemblies of ZnS-Au could be promisingly utilized in the long-term course of photocatalysis. The present study provides a new paradigm for designing the highly efficient semiconductor/metal hybrid photocatalysts that can effectively produce chemical energy from light.

  6. Effects of wind energy production on growth, demography, and survivorship of a Desert Tortoise (Gopherus agassizii) population in Southern California with comparisons to natural populations

    Science.gov (United States)

    Lovich, J.E.; Ennen, J.R.; Madrak, S.; Meyer, K.; Loughran, C.; Bjurlin, C.; Arundel, T.; Turner, W.; Jones, C.; Groenendaal, G.M.

    2011-01-01

    We studied a Desert Tortoise (Gopherus agassizii) population at a large wind energy generation facility near Palm Springs, California over six field seasons from 1997 to 2010. We compared growth and demographic parameters to populations living in less disturbed areas; as well as populations of the closely-related and newly-described G. morafkai elsewhere in the Sonoran Desert of Arizona. We marked 69 individuals of all size classes and estimated a population size of 96 tortoises, or about 15.4/km2. Growth rates for males were lower than reported elsewhere, although maximum body size was larger. The smallest female with shelled eggs was 221 mm and males mature at over 200 mm. Mean male size was greater than that of females. The adult sex ratio was not significantly different from unity. Size frequency histograms were similar over time and when compared to most, but not all, G. morafkai populations in the Sonoran Desert. For a cohort of adult females, we estimated mortality at 8.4% annually due, in part, to site operations. This value was low in comparison to many other populations during the same time period. Other than possible differences in growth rate of males and the high survivorship of females, there appear to be few differences between this population and those in more natural areas. The high productivity of food plants at the site and its limited public access may contribute to the overall stability of the population. However, the effects of utility-scale renewable energy development on tortoises in other, less productive, areas are unknown. Additional research (especially controlled and replicated before and after studies) is urgently needed to address this deficiency because of forecasted expansion of utility-scale renewable energy development in the future.

  7. Involvement of Fibroblast Growth Factor Receptor Genes in Benign Prostate Hyperplasia in a Korean Population

    Directory of Open Access Journals (Sweden)

    Hae Jeong Park

    2013-01-01

    Full Text Available Fibroblast growth factors (FGFs and their receptors (FGFRs have been implicated in prostate growth and are overexpressed in benign prostatic hyperplasia (BPH. In this study, we investigated whether single nucleotide polymorphisms (SNPs of the FGFR genes (FGFR1 and FGFR2 were associated with BPH and its clinical phenotypes in a population of Korean men. We genotyped four SNPs in the exons of FGFR1 and FGFR2 (rs13317 in FGFR1; rs755793, rs1047100, and rs3135831 in FGFR2 using direct sequencing in 218 BPH patients and 213 control subjects. No SNPs of FGFR1 or FGFR2 genes were associated with BPH. However, analysis according to clinical phenotypes showed that rs1047100 of FGFR2 was associated with prostate volume in BPH in the dominant model (GA/AA versus GG, P = 0.010. In addition, a significant association was observed between rs13317 of FGFR1 and international prostate symptom score (IPSS in the additive (TC versus CC versus TT, P = 0.0022 and dominant models (TC/CC versus TT, P = 0.005. Allele frequency analysis also showed significant association between rs13317 and IPSS (P = 0.005. These results suggested that FGFR genes could be related to progression of BPH.

  8. Growth performance, carcass yield and intestinal microflora populations of broilers fed diets containing thepax and yogurt

    Directory of Open Access Journals (Sweden)

    A Boostani

    2013-03-01

    Full Text Available The present study aimed at evaluating the effect of the probiotic thepax and yogurt (as probiotic on the growth response and intestinal microflora results of broiler chickens. Two hundred forty day-old Ross 308 broilers were equally distributed into 12 floor pens and reared for 42 day. The treatments consisted of yogurt (10, 5 and 2.5% during starter, grower and finisher periods in the drinking water, respectively and thepax (1000, 500, 250 g/ton-1 in the starter, grower and finisher diets, respectively, resulting three experimental diets and a control group. Each dietary treatment was fed ad-libitum to four replicate group of 20 birds at the beginning of rearing period. Birds and feed were weighed on days 21 and 42. The results of experiment indicate that diets containing feed additives improved broiler performance. The body weight gain and feed conversion ratio improved significantly more (p < 0.05 with the thepax treatment compared with the control broilers during the total rearing period. The highest (p < 0.05 carcass and thigh values were recorded for broilers fed the diet supplemented with thepax and yogurt, respectively. The lowest abdominal fat pad value was obtained in broilers fed the diet supplemented with thepax. On d 21, thepax and yogurt significantly reduced (p < 0.05 cecal Escherichia coli and Clostridium perfringens populations compared with the control group. In conclusion, thepax and yogurt improved broilers growth response and conferred intestinal health benefits to chickens by improving their microbial ecology.

  9. Intrauterine growth standards: a cross-sectional study in a population of Nigerian newborns

    Directory of Open Access Journals (Sweden)

    Olugbenga A. Mokuolu

    2012-09-01

    Full Text Available The aim of the study was to define an intrauterine growth curve for a population of Nigerian newborn babies. A cross-sectional observational study design was adopted. Weight, length and head circumference were all measured in consecutive singleton deliveries at the University of Ilorin Teaching Hospital over a 3-year period. Gestational age (GA of the babies was estimated from the last menstrual period or first trimester ultrasound. The estimates obtained were clinically validated using the Ballard score. Mean birth weights and percentiles of the weight, length and head circumferences for the respective GA were estimated using the SPSS 15 software package. A total of 5273 babies were recruited for the study with GA ranging from 25-44 weeks. Comparison of the mean birth weights of the various GA with the data from Denver, Colorado, showed that Nigerian babes tended to weigh less at the early GA, although these differences were not statistically significant. Between 26-36 weeks, the average weights of both sexes were similar; however, beyond this time point there was a consistent increase in the average weight of the males over the female babies. Growth curves for Nigerian newborn babies were generated and showed that the mean birth weight of Nigerian preterm babies was lighter than that of babies in Colorado. The impact of these differences on the classification of newborns will require further evaluation.

  10. Phenotypic diversity and population growth in fluctuating environment: a MBPRE approach

    CERN Document Server

    Dombry, Clément; Bansaye, Vincent

    2009-01-01

    Organisms adapt to fluctuating environments by regulating their dynamics, and by adjusting their phenotypes to environmental changes. We model population growth using multitype branching processes in random environments, where the offspring distribution of some organism having trait $t\\in\\cT$ in environment $e\\in\\cE$ is given by some (fixed) distribution $\\Upsilon_{t,e}$ on $\\bbN$. Then, the phenotypes are attributed using a distribution (strategy) $\\pi_{t,e}$ on the trait space $\\cT$. We look for the optimal strategy $\\pi_{t,e}$, $t\\in\\cT$, $e\\in\\cE$ maximizing the net growth rate or Lyapounov exponent, and characterize the set of optimal strategies. This is considered for various models of interest in biology: hereditary versus non-hereditary strategies and strategies involving or not involving a sensing mechanism. Our main results are obtained in the setting of non-hereditary strategies: thanks to a reduction to simple branching processes in random environment, we derive an exact expression for the net gro...

  11. Compound haplotypes at Xp11.23 and human population growth in Eurasia.

    Science.gov (United States)

    Alonso, S; Armour, J A L

    2004-09-01

    To investigate patterns of diversity and the evolutionary history of Eurasians, we have sequenced a 2.8 kb region at Xp11.23 in a sample of African and Eurasian chromosomes. This region is in a long intron of CLCN5 and is immediately flanked by a highly variable minisatellite, DXS255, and a human-specific Ta0 LINE. Compared to Africans, Eurasians showed a marked reduction in sequence diversity. The main Euro-Asiatic haplotype seems to be the ancestral haplotype for the whole sample. Coalescent simulations, including recombination and exponential growth, indicate a median length of strong linkage disequilibrium, up to approximately 9 kb for this area. The Ka/Ks ratio between the coding sequence of human CLCN5 and its mouse orthologue is much less than 1. This implies that the region sequenced is unlikely to be under the strong influence of positive selective processes on CLCN5, mutations in which have been associated with disorders such as Dent's disease. In contrast, a scenario based on a population bottleneck and exponential growth seems a more likely explanation for the reduced diversity observed in Eurasians. Coalescent analysis and linked minisatellite diversity (which reaches a gene diversity value greater than 98% in Eurasians) suggest an estimated age of origin of the Euro-Asiatic diversity compatible with a recent out-of-Africa model for colonization of Eurasia by modern Homo sapiens.

  12. Population ageing, policy reforms and economic growth in Japan: a computable OLG model with endogenous growth mechanism

    OpenAIRE

    Manabu Shimasawa

    2007-01-01

    We have developed a computable endogenous growth OLG model generated by the accumulation of human capital. To study whether policy reform against aging make any quantitative impacts through human capital formation on the Japanese economy and whether it has long-run effect, we simulate two policy change scenarios and compare the results of those with endogenous growth to those with exogenous growth. The results are very encouraging: (i) policy changes promote human capital accumulation and thu...

  13. The Influencing Factors on Population Growth in Metropolises from the Viewpoints of Experts: Case Study of Tehran

    Directory of Open Access Journals (Sweden)

    F. Mansourian

    2016-02-01

    Full Text Available The present paper aims to find the factors influencing population growth in metropolises and thus provide a model for population growth in large cities based on expert opinions. Considering the fact that the multiple factors associated with life in the metropolis, affecting immigration, fertility and mortality, are from different fields, including economic, social, and cultural domains, this article is of an interdisciplinary nature. In the present article while the theoretical concepts are reviewed, the important factors affecting population growth are identified, and then grouped and studied as economic, cultural and social, geographical, infrastructural and urban facilities factors; following that a basic conceptual model is extracted. In this paper, a researcher-made questionnaire is distributed among thirty experts on demography, sociology, and economics. The analytic hierarchy process (AHP applied in this study showed that the “economic factors” have the greatest impact on the population growth in the metropolis of Tehran; and socio-cultural, infrastructural and geographical factors and urban facilities have lesser impacts. Also, in the final prioritizing, of the eleven sub-factors, the sub-factors of occupation, income, lifestyle, individual values and the cost of living, which had the greatest weight, were analyzed. At the end, the final model of population growth in metropolises is provided.

  14. Controlling the Growth of Future LEO Debris Populations with Active Debris Removal

    Science.gov (United States)

    Liou, J.-C.; Johnson, N. L.; Hill, N. M.

    2008-01-01

    Active debris removal (ADR) was suggested as a potential means to remediate the low Earth orbit (LEO) debris environment as early as the 1980s. The reasons ADR has not become practical are due to its technical difficulties and the high cost associated with the approach. However, as the LEO debris populations continue to increase, ADR may be the only option to preserve the near-Earth environment for future generations. An initial study was completed in 2007 to demonstrate that a simple ADR target selection criterion could be developed to reduce the future debris population growth. The present paper summarizes a comprehensive study based on more realistic simulation scenarios, including fragments generated from the 2007 Fengyun-1C event, mitigation measures, and other target selection options. The simulations were based on the NASA long-term orbital debris projection model, LEGEND. A scenario, where at the end of mission lifetimes, spacecraft and upper stages were moved to 25-year decay orbits, was adopted as the baseline environment for comparison. Different annual removal rates and different ADR target selection criteria were tested, and the resulting 200-year future environment projections were compared with the baseline scenario. Results of this parametric study indicate that (1) an effective removal strategy can be developed based on the mass and collision probability of each object as the selection criterion, and (2) the LEO environment can be stabilized in the next 200 years with an ADR removal rate of five objects per year.

  15. Whole genomic prediction of growth and carcass traits in a Chinese quality chicken population.

    Science.gov (United States)

    Zhang, Z; Xu, Z-Q; Luo, Y-Y; Zhang, H-B; Gao, N; He, J-L; Ji, C-L; Zhang, D-X; Li, J-Q; Zhang, X-Q

    2017-01-01

    By incorporating high-density markers into breeding value prediction models, the whole genomic prediction (WGP) method can effectively accelerate genetic improvement in livestock breeding. However, the performance of WGP varies across species and populations and is affected by the underlying genetic architecture. In particular, very little is known about the performance of WGP for many chicken breeds. Here we estimate the genetic parameters and evaluate the performance of WGP for 18 growth and carcass traits in a Chinese quality chicken population. In total, 435 chickens were systematically phenotyped and genotyped using a 600K genotyping array. Two variance component estimation scenarios, 3 breeding value prediction methods, and 2 validation procedures were compared. The results showed that the heritability of these 18 traits was medium to high (ranging from 0.28 to 0.60) and that deviations existed between the heritability estimated from pedigrees and markers. Compared with conventional breeding methods, WGP could potentially increase the selection accuracy by 20% or more depending on the prediction model used, the trait under consideration, and the genetic connectedness between the training and validation individuals. Our results showed the potential of implementing genomic selection in small breeding herds.

  16. Modeling Growth Trend and Forecasting Techniques for Vehicular Population in India

    Directory of Open Access Journals (Sweden)

    Kartikeya Jha

    2013-06-01

    Full Text Available Forecasting and estimation of growth in vehicular population is a sine qua non of any major transportation engineering development, requires capturing the past trend and using it to predict the future trend based on qualified assumptions, simulations and models created using explanatory variables. This work attempts to review the in vogue approaches and investigate a more contemporary approach, the Time Series (TS Analysis. Three fundamentally different methods were explored and results from each of these analyses were collated to check for respective levels of accuracy in predicting vehicular population for the same target year. Within the scope of this study and estimation, results obtained from TS Analysis were found to be considerably more accurate than those from Trend Line Analysis and observably better than those from Econometric Analysis. To reinforce these observations and inferences drawn, a second set of analysis was done on more recent input by using AADT data from PeMS, California. Inter alia this was carried out to contrast any statistical improvement observed when doing TS analysis with rich and accurate data. With all the data sets used and locations analyzed for forecasting, the Time Series analysis technique was invariably found to be a potent tool for forecasting.

  17. Effect of Portulaca oleracea extracts on growth performance and microbial populations in ceca of broilers.

    Science.gov (United States)

    Zhao, X H; He, X; Yang, X F; Zhong, X H

    2013-05-01

    The aim of this study was to investigate the effects of Portulaca oleracea extracts on growth performance and microbial populations in the ceca of broilers. A total of 120 one-day-old broilers were randomly divided into 3 groups. Portulaca oleracea extracts were added to diets at 0.2 and 0.4% (wt/wt; POL-0.2, POL-0.4), respectively. The control (CON) group was administered with no P. oleracea extract supplementation. Body weight gain and feed conversion ratio were recorded every 2 wk. On d 28 and 42, the cecal contents were collected and assayed for Escherichia coli, Lactobacillus, and Bifidobacterium populations. Additionally, the pH of the ileum and cecum was measured. The results showed that both on d 28 and 42 BW gain of P. oleracea extract supplementation groups was significantly higher, whereas the feed conversion ratio was lower (P < 0.05) compared with CON. On d 28 and 42, significantly (P < 0.05) fewer E. coli were recovered from ceca of broilers provided with the POL-0.2 diet than from broilers provided with the control diet. The quantities of Lactobacillus and Bifidobacterium of POL-0.2 were significantly (P < 0.05) higher than CON. Results showed P. oleracea extracts have no distinct influence on intestinal pH. These data suggest that P. oleracea extract supplementation significantly altered the cecal bacterial community without affecting the intestinal pH.

  18. GADD45β Determines Chemoresistance and Invasive Growth of Side Population Cells of Human Embryonic Carcinoma

    Directory of Open Access Journals (Sweden)

    Toshihiko Inowa

    2010-01-01

    Full Text Available Side population (SP cells are an enriched population of stem, and the existence of SP cells has been reported in human cancer cell lines. In this study, we performed an SP analysis using 11 human cancer cell lines and confirmed the presence of SP cells in an embryonic carcinoma cell line, NEC8. NEC8 SP cells showed characteristics of cancer stem cells, such as high growth rate, chemoresistance and high invasiveness. To further characterize the NEC8 SP cells, we used DNA microarrays. Among 38,500 genes, we identified 12 genes that were over-expressed in SP cells and 1 gene that was over-expressed in non-SP cells. Among these 13 genes, we focused on GADD45b. GADD45b was over-expressed in non-SP cells, but the inhibition of GADD45b had no effect on non-SP cells. Paradoxically, the inhibition of GADD45b significantly reduced the viability of NEC8 SP cells. The inhibition of ABCG2, which determines the SP phenotype, had no effect on the invasiveness of NEC8 SP cells, but the inhibition of GADD45b significantly reduced invasiveness. These results suggest that GADD45b, but not ABCG2, might determine the cancer stem cell-like phenotype, such as chemoresistance and the high invasiveness of NEC8 SP cells, and might be a good therapeutic target.

  19. Defining and explaining tropical deforestation: shifting cultivation and population growth in colonial Madagascar (1896-1940).

    Science.gov (United States)

    Jarosz, L

    1993-10-01

    The case study of deforestation in Madagascar demonstrated how deforestation is a complex phenomenon that reflects interconnections between land-based resources, human groups, and global political economy; specifically, there is a link between changing land use practices affecting shifting cultivation and tropical deforestation. The general development model of exponential population growth and shifting cultivation causing deforestation and environmental degradation is too simplified, places undue blame on the victims, and isolates shifting cultivation practices from the reality of land use patterns in specific places at specific times. Problematic also is the way definition, delimitation, and discussion of environmental problems shapes possible solutions. This analysis suggests a theoretical view that links reconstructed regional geography with political ecology. The assertion is that deforestation is historically based on multiple social processes within Madagascar. Land use practices and resource access decisions during the colonial period affected land management and degradation. The colonial state policy played a role in the destruction of tropical flora by fire, shifting cultivation, and grazing, and the responses of Europeans and Malagasys. Context and multiplicity of motivations and practices were key. A review was presented of reconstructed regional geography and political ecology and global tropical deforestation. The description of the political economy of deforestation during colonial times focused on the movement of population into the forests after 1896 and French annexation. Famine resulted. Shifting cultivation laws were passed between 1881 and 1913, due to the desire for rational forest resource management. Ecologically and socially these rules were difficult to enforce; there were resistance due to the threat of the elimination of subsistence living for wage work. Destructive logging practices and forest product extraction after 1921 are described

  20. Mating system, population growth, and management scenario for Kalanchoe pinnata in an invaded seasonally dry tropical forest.

    Science.gov (United States)

    González de León, Salvador; Herrera, Ileana; Guevara, Roger

    2016-07-01

    Ecological invasions are a major issue worldwide, where successful invasion depends on traits that facilitate dispersion, establishment, and population growth. The nonnative succulent plant Kalanchoe pinnata, reported as invasive in some countries, is widespread in remnants of seasonally dry tropical forest on a volcanic outcrop with high conservation value in east-central Mexico where we assessed its mating system and demographic growth and identified management strategies. To understand its local mating system, we conducted hand-pollination treatments, germination, and survival experiments. Based on the experimental data, we constructed a life-stage population matrix, identified the key traits for population growth, weighted the contributions of vegetative and sexual reproduction, and evaluated management scenarios. Hand-pollination treatments had slight effects on fruit and seed setting, as well as on germination. With natural pollination treatment, the successful germination of seeds from only 2/39 fruit suggests occasional effective natural cross-pollination. The ratios of the metrics for self- and cross-pollinated flowers suggest that K. pinnata is partially self-compatible. Most of the pollinated flowers developed into fruit, but the seed germination and seedling survival rates were low. Thus, vegetative propagation and juvenile survival are the main drivers of population growth. Simulations of a virtual K. pinnata population suggest that an intense and sustained weeding campaign will reduce the population within at least 10 years. Synthesis and applications. The study population is partially self-compatible, but sexual reproduction by K. pinnata is limited at the study site, and population growth is supported by vegetative propagation and juvenile survival. Demographic modeling provides key insights and realistic forecasts on invasion process and therefore is useful to design management strategies.

  1. Modeling effects of cadmium on population growth of Palaemonetes pugio: Results of a full life cycle exposure

    Energy Technology Data Exchange (ETDEWEB)

    Manyin, Teresa [University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, PO Box 38, 1 Williams Street, Solomons, MD 20688 (United States)], E-mail: manyin@cbl.umces.edu; Rowe, Christopher L. [University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, PO Box 38, 1 Williams Street, Solomons, MD 20688 (United States)

    2008-06-23

    In an 8-month laboratory experiment, Palaemonetes pugio (grass shrimp) were exposed to aqueous cadmium (free cadmium ion concentrations of 1.51 or 2.51 {mu}g Cd{sup 2+}/L) for an entire life cycle, from larva to reproductive adult and through to production of second-generation larva. Individual-level effects on survival, life stage duration, and reproduction were measured, and population growth was projected using two models: a stage-based matrix model and a z-transformed life cycle graph analysis. Adult survival was significantly reduced at 2.51 {mu}g Cd{sup 2+}/L, but cadmium exposure had no effects on survival or stage duration of embryos, larvae, or juveniles. Survival of second-generation larvae was unaffected by maternal exposure. Brood size was reduced by 27% at 1.51 {mu}g Cd{sup 2+}/L and by 36% at 2.51 {mu}g Cd{sup 2+}/L. The percent of females in the population that was gravid was approximately 50% lower at 2.51 {mu}g Cd{sup 2+}/L, compared to controls. Both population models projected a dose-dependent decrease in population growth rate ({lambda}), up to a 12% reduction at 2.51 {mu}g Cd{sup 2+}/L, which can be attributed mainly to contributions from reproductive effects. Elasticity analysis revealed that population growth rate was most sensitive to changes in survival of juveniles and adults. However, lethal effects of cadmium made only a small contribution to the effect on population growth rate. Even though both models project positive growth ({lambda} > 1) of grass shrimp populations exposed to low concentrations of cadmium, the ability of populations to withstand predation pressure would be compromised.

  2. Vascular endothelial growth factor (VEGFA gene variation in polycystic ovary syndrome in a Tunisian women population

    Directory of Open Access Journals (Sweden)

    Assila Ben Salem

    2016-10-01

    Full Text Available Abstract Background Polycystic ovary syndrome (PCOS is characterized by the growth of a number of small cysts on the ovaries which leads to sex hormonal imbalance. Women who are affected by this syndrome suffer from irregular menstrual cycles, decline in their fertility, excessive hair growth, obesity, acne and most importantly cardiac function problems. The vascular endothelial growth factor (VEGF plays a pivotal role in tissue vascularization in general and in the pathogenesis of many diseases. The PCOS was found to be associated with high expression levels of VEGF. In women who undergo assisted reproductive procedures (ART, VEGF was found to be a key mediator of other factors to control ovary angiogenesis. Here, we set out to examine the association of VEGFA gene polymorphism with PCOS and its components in a population of Tunisia women to enhance our understanding of the genetic background leading angiogenesis and vascularization abnormalities in PCOS. Methods The association of VEGFA gene with PCOS and its components was examined in a cohort of 268 women from Tunisia involving 118 PCOS patients and 150 controls. VEGFA gene variations were assessed through the analysis of the following SNPs rs699947 (A/C, rs833061 (C/T, rs1570360 (G/A, rs833068 (G/A, rs3025020 (C/T, and rs3025039 (C/T. The linkage disequilibrium between SNPs was assessed using HAPLOVIEW software while combination of SNPs into haplotypes in the population and the reconstruction of the cladogram were carried-out by PHASE and ARLEQUIN programs, respectively. Genetic association and genotype-phenotype correlations were calculated by logistic regression and non-parametric tests (Kruskall-Wallis and Mann–Whitney tests, respectively, using StatView program. Results We observed 10 haplotypes in our studied cohort whereH1 (ACGG, H2 (ACAG, H7 (CTGG and H8 (CTGA were the most frequent. We observed the association of the genotype CT of the SNP rs30225039 with PCOS phenotype (P = 0

  3. Combining forces--the use of Landsat TM satellite imagery, soil parameter information, and multiplex PCR to detect Coccidioides immitis growth sites in Kern County, California.

    Directory of Open Access Journals (Sweden)

    Antje Lauer

    Full Text Available Coccidioidomycosis is a fungal disease acquired through the inhalation of spores of Coccidioides spp., which afflicts primarily humans and other mammals. It is endemic to areas in the southwestern United States, including the San Joaquin Valley portion of Kern County, California, our region of interest (ROI. Recently, incidence of coccidioidomycosis, also known as valley fever, has increased significantly, and several factors including climate change have been suggested as possible drivers for this observation. Up to date details about the ecological niche of C. immitis have escaped full characterization. In our project, we chose a three-step approach to investigate this niche: 1 We examined Landsat-5-Thematic-Mapper multispectral images of our ROI by using training pixels at a 750 m × 750 m section of Sharktooth Hill, a site confirmed to be a C. immitis growth site, to implement a Maximum Likelihood Classification scheme to map out the locations that could be suitable to support the growth of the pathogen; 2 We used the websoilsurvey database of the US Department of Agriculture to obtain soil parameter data; and 3 We investigated soil samples from 23 sites around Bakersfield, California using a multiplex Polymerase Chain Reaction (PCR based method to detect the pathogen. Our results indicated that a combination of satellite imagery, soil type information, and multiplex PCR are powerful tools to predict and identify growth sites of C. immitis. This approach can be used as a basis for systematic sampling and investigation of soils to detect Coccidioides spp.

  4. Combining forces--the use of Landsat TM satellite imagery, soil parameter information, and multiplex PCR to detect Coccidioides immitis growth sites in Kern County, California.

    Science.gov (United States)

    Lauer, Antje; Talamantes, Jorge; Castañón Olivares, Laura Rosío; Medina, Luis Jaime; Baal, Joe Daryl Hugo; Casimiro, Kayla; Shroff, Natasha; Emery, Kirt W

    2014-01-01

    Coccidioidomycosis is a fungal disease acquired through the inhalation of spores of Coccidioides spp., which afflicts primarily humans and other mammals. It is endemic to areas in the southwestern United States, including the San Joaquin Valley portion of Kern County, California, our region of interest (ROI). Recently, incidence of coccidioidomycosis, also known as valley fever, has increased significantly, and several factors including climate change have been suggested as possible drivers for this observation. Up to date details about the ecological niche of C. immitis have escaped full characterization. In our project, we chose a three-step approach to investigate this niche: 1) We examined Landsat-5-Thematic-Mapper multispectral images of our ROI by using training pixels at a 750 m × 750 m section of Sharktooth Hill, a site confirmed to be a C. immitis growth site, to implement a Maximum Likelihood Classification scheme to map out the locations that could be suitable to support the growth of the pathogen; 2) We used the websoilsurvey database of the US Department of Agriculture to obtain soil parameter data; and 3) We investigated soil samples from 23 sites around Bakersfield, California using a multiplex Polymerase Chain Reaction (PCR) based method to detect the pathogen. Our results indicated that a combination of satellite imagery, soil type information, and multiplex PCR are powerful tools to predict and identify growth sites of C. immitis. This approach can be used as a basis for systematic sampling and investigation of soils to detect Coccidioides spp.

  5. Declines in low-elevation subalpine tree populations outpace growth in high-elevation populations with warming

    Science.gov (United States)

    Conlisk, Erin; Castanha, Cristina; Germino, Matthew J.; Veblen, Thomas T; Smith, Jeremy M.; Kueppers, Lara M.

    2017-01-01

    Species distribution shifts in response to climate change require that recruitment increase beyond current range boundaries. For trees with long life spans, the importance of climate-sensitive seedling establishment to the pace of range shifts has not been demonstrated quantitatively.Using spatially explicit, stochastic population models combined with data from long-term forest surveys, we explored whether the climate-sensitivity of recruitment observed in climate manipulation experiments was sufficient to alter populations and elevation ranges of two widely distributed, high-elevation North American conifers.Empirically observed, warming-driven declines in recruitment led to rapid modelled population declines at the low-elevation, ‘warm edge’ of subalpine forest and slow emergence of populations beyond the high-elevation, ‘cool edge’. Because population declines in the forest occurred much faster than population emergence in the alpine, we observed range contraction for both species. For Engelmann spruce, this contraction was permanent over the modelled time horizon, even in the presence of increased moisture. For limber pine, lower sensitivity to warming may facilitate persistence at low elevations – especially in the presence of increased moisture – and rapid establishment above tree line, and, ultimately, expansion into the alpine.Synthesis. Assuming 21st century warming and no additional moisture, population dynamics in high-elevation forests led to transient range contractions for limber pine and potentially permanent range contractions for Engelmann spruce. Thus, limitations to seedling recruitment with warming can constrain the pace of subalpine tree range shifts.

  6. Genetic improvement on Chinese shrimp (Fenneropenaeuschinensis): growth and viability performance in F1 hybrids of different populations

    Institute of Scientific and Technical Information of China (English)

    TIAN Yi; KONG Jie; LI Wendong; LUAN Sheng; YANG Cuihua; WANG Qingyin

    2008-01-01

    Fenneropenaeus chinensis distributed in the Yellow Sea and Bohai Sea of China and the west coast of the Korean Peninsula. Different geographical populations represent potentially different genetic resources. To learn further the characteristics of different geographical population, crosses among two wild and three farmed populations were produced. The two wild populations were from the Yellow Sea and Bohai Sea (WYP), and the west coast of the Korean Peninsula and coast (WKN). The three farmed populations included the offspring of first generation of wild shrimp from coast in Korea (FKN), the Huang Hai (the Yellow Sea in Chinese) No. 1 (HH 1), and JK98. The phenotypes growth and survival rates of these populations were compared to confirm the feasibility for crossbreeding. The body length (BL), carapace length (CL), carapace width (CW), height of the second and third abdominal segment (HST), width of the second and third abdominal segment (WST), length of the first abdominal segment (LF), length of the last abdominal segment (LL), live body weight (BW), and survival rate were measured. Different combinations were statistically performed with ANOVA and Duncan's Multiple significant difference (P<0.05) in BL, CL, HST, LL, and BW; and insignificant difference (P0.05) in other growth traits and survival rate. The results of Duncan's Multiple Range Test are that BL and CL of was the best combination in all growth traits. Therefore, hybridization can introduce the variation to base populations. The systematic selection program based on additive genetic performance may be more effective than crossbreeding.

  7. Strategic removal of host trees in isolated, satellite infestations of emerald ash borer can reduce population growth

    Science.gov (United States)

    Samuel J. Fahrner; Mark Abrahamson; Robert C. Venette; Brian H. Aukema

    2017-01-01

    Emerald ash borer is an invasive beetle causing significant mortality of ash trees (Fraxinus spp.) in North America and western Russia. The invasive range has expanded to more than half of the states in the United States since the initial detection in Michigan, USA in 2002. Emerald ash borer is typically managed with a combination of techniques...

  8. Monitoring and Characterizing Seasonal Drought, Water Supply Pattern and Their Impact on Vegetation Growth Using Satellite Soil Moisture Data, GRACE Water Storage and In-situ Observations.

    Science.gov (United States)

    A, G.; Velicogna, I.; Kimball, J. S.; Kim, Y.; Colliander, A.; Njoku, E. G.

    2015-12-01

    We combine soil moisture (SM) data from AMSR-E, AMSR-2 and SMAP, terrestrial water storage (TWS) changes from GRACE, in-situ groundwater measurements and atmospheric moisture data to delineate and characterize the evolution of drought and its impact on vegetation growth. GRACE TWS provides spatially continuous observations of total terrestrial water storage changes and regional drought extent, persistence and severity, while satellite derived soil moisture estimates provide enhanced delineation of plant-available soil moisture. Together these data provide complementary metrics quantifying available plant water supply. We use these data to investigate the supply changes from water components at different depth in relation to satellite based vegetation metrics, including vegetation greenness (NDVI) measures from MODIS and related higher order productivity (GPP) before, during and following the major drought events observed in the continental US for the past 14 years. We observe consistent trends and significant correlations between monthly time series of TWS, SM, NDVI and GPP. We study how changes in atmosphere moisture stress and coupling of water storage components at different depth impact on the spatial and temporal correlation between TWS, SM and vegetation metrics. In Texas, we find that surface SM and GRACE TWS agree with each other in general, and both capture the underlying water supply constraints to vegetation growth. Triggered by a transit increase in precipitation following the 2011 hydrological drought, vegetation productivity in Texas shows more sensitivity to surface SM than TWS. In the Great Plains, the correspondence between TWS and vegetation productivity is modulated by temperature-induced atmosphere moisture stress and by the coupling between surface soil moisture and groundwater through irrigation.

  9. Characterizing Seasonal Drought, Water Supply Pattern and Their Impact on Vegetation Growth Using Satellite Soil Moisture Data, GRACE Water Storage and Precipitation Observations

    Science.gov (United States)

    A, G.; Velicogna, I.; Kimball, J. S.; Du, J.; Kim, Y.; Njoku, E. G.; Colliander, A.

    2016-12-01

    We combine soil moisture (SM) data from AMSR-E, AMSR-2 and SMAP, terrestrial water storage (TWS) changes from GRACE and precipitation measurements from GPCP to delineate and characterize drought and water supply pattern and its impact on vegetation growth. GRACE TWS provides spatially continuous observations of total terrestrial water storage changes and regional drought extent, persistence and severity, while satellite derived soil moisture estimates provide enhanced delineation of plant-available soil moisture. Together these data provide complementary metrics quantifying available plant water supply and have important implications for water resource management. We use these data to investigate the supply changes from different water components in relation to satellite based vegetation productivity metrics from MODIS, before, during and following the major drought events observed in the continental US during the past 13 years. We observe consistent trends and significant correlations between monthly time series of TWS, SM, and vegetation productivity. In Texas and surrounding semi-arid areas, we find that the spatial pattern of the vegetation-moisture relation follows the gradient in mean annual precipitation. In Texas, GRACE TWS and surface SM show strong coupling and similar characteristic time scale in relatively normal years, while during the 2011 onward hydrological drought, GRACE TWS manifests a longer time scale than that of surface SM, implying stronger drought persistence in deeper water storage. In the Missouri watershed, we find a spatially varying vegetation-moisture relationship where in the drier northwestern portion of the basin, the inter-annual variability in summer vegetation productivity is closely associated with changes in carry-on GRACE TWS from spring, whereas in the moist southeastern portion of the basin, summer precipitation is the dominant controlling factor on vegetation growth.

  10. Core-satellite populations and seasonality of water meter biofilms in a metropolitan drinking water distribution system

    KAUST Repository

    Ling, Fangqiong

    2015-08-07

    © 2015 International Society for Microbial Ecology Drinking water distribution systems (DWDSs) harbor the microorganisms in biofilms and suspended communities, yet the diversity and spatiotemporal distribution have been studied mainly in the suspended communities. This study examined the diversity of biofilms in an urban DWDS, its relationship with suspended communities and its dynamics. The studied DWDS in Urbana, Illinois received conventionally treated and disinfected water sourced from the groundwater. Over a 2-year span, biomass were sampled from household water meters (n=213) and tap water (n=20) to represent biofilm and suspended communities, respectively. A positive correlation between operational taxonomic unit (OTU) abundance and occupancy was observed. Examined under a ‘core-satellite’ model, the biofilm community comprised 31 core populations that encompassed 76.7% of total 16 S rRNA gene pyrosequences. The biofilm communities shared with the suspended community highly abundant and prevalent OTUs, which related to methano-/methylotrophs (i.e., Methylophilaceae and Methylococcaceae) and aerobic heterotrophs (Sphingomonadaceae and Comamonadaceae), yet differed by specific core populations and lower diversity and evenness. Multivariate tests indicated seasonality as the main contributor to community structure variation. This pattern was resilient to annual change and correlated to the cyclic fluctuations of core populations. The findings of a distinctive biofilm community assemblage and methano-/methyltrophic primary production provide critical insights for developing more targeted water quality monitoring programs and treatment strategies for groundwater-sourced drinking water systems.The ISME Journal advance online publication, 7 August 2015; doi:10.1038/ismej.2015.136.

  11. The Phase Space and Stellar Populations of Cluster Galaxies at z ~ 1: Simultaneous Constraints on the Location and Timescale of Satellite Quenching

    Science.gov (United States)

    Muzzin, Adam; van der Burg, R. F. J.; McGee, Sean L.; Balogh, Michael; Franx, Marijn; Hoekstra, Henk; Hudson, Michael J.; Noble, Allison; Taranu, Dan S.; Webb, Tracy; Wilson, Gillian; Yee, H. K. C.

    2014-11-01

    We investigate the velocity versus position phase space of z ~ 1 cluster galaxies using a set of 424 spectroscopic redshifts in nine clusters drawn from the GCLASS survey. Dividing the galaxy population into three categories, that is, quiescent, star-forming, and poststarburst, we find that these populations have distinct distributions in phase space. Most striking are the poststarburst galaxies, which are commonly found at small clustercentric radii with high clustercentric velocities, and appear to trace a coherent "ring" in phase space. Using several zoom simulations of clusters, we show that the coherent distribution of the poststarbursts can be reasonably well reproduced using a simple quenching scenario. Specifically, the phase space is best reproduced if these galaxies are quenched with a rapid timescale (0.1 0.5 Gyr) or by quenching galaxies at larger radii (R ~ R 200). We compare this quenching timescale to the timescale implied by the stellar populations of the poststarburst galaxies and find that the poststarburst spectra are well-fit by a rapid quenching (τ Q = 0.4+0.3-0.4 Gyr) of a typical star-forming galaxy. The similarity between the quenching timescales derived from these independent indicators is a strong consistency check of the quenching model. Given that the model implies satellite quenching is rapid and occurs well within R 200, this would suggest that ram-pressure stripping of either the hot or cold gas component of galaxies are the most plausible candidates for the physical mechanism. The high cold gas consumption rates at z ~ 1 make it difficult to determine whether hot or cold gas stripping is dominant; however, measurements of the redshift evolution of the satellite quenching timescale and location may be capable of distinguishing between the two. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on

  12. The phase space and stellar populations of cluster galaxies at z ∼ 1: simultaneous constraints on the location and timescale of satellite quenching

    Energy Technology Data Exchange (ETDEWEB)

    Muzzin, Adam; Van der Burg, R. F. J.; McGee, Sean L.; Balogh, Michael; Franx, Marijn; Hoekstra, Henk [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Hudson, Michael J. [Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Noble, Allison; Taranu, Dan S.; Yee, H. K. C. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Webb, Tracy [Department of Physics, McGill University, Montréal, QC (Canada); Wilson, Gillian [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States)

    2014-11-20

    We investigate the velocity versus position phase space of z ∼ 1 cluster galaxies using a set of 424 spectroscopic redshifts in nine clusters drawn from the GCLASS survey. Dividing the galaxy population into three categories, that is, quiescent, star-forming, and poststarburst, we find that these populations have distinct distributions in phase space. Most striking are the poststarburst galaxies, which are commonly found at small clustercentric radii with high clustercentric velocities, and appear to trace a coherent 'ring' in phase space. Using several zoom simulations of clusters, we show that the coherent distribution of the poststarbursts can be reasonably well reproduced using a simple quenching scenario. Specifically, the phase space is best reproduced if these galaxies are quenched with a rapid timescale (0.1 <τ {sub Q} < 0.5 Gyr) after they make their first passage of R ∼ 0.5 R {sub 200}, a process that takes a total time of ∼1 Gyr after first infall. The poststarburst phase space is not well reproduced using long quenching timescales (τ {sub Q} > 0.5 Gyr) or by quenching galaxies at larger radii (R ∼ R {sub 200}). We compare this quenching timescale to the timescale implied by the stellar populations of the poststarburst galaxies and find that the poststarburst spectra are well-fit by a rapid quenching (τ {sub Q} = 0.4{sub −0.4}{sup +0.3} Gyr) of a typical star-forming galaxy. The similarity between the quenching timescales derived from these independent indicators is a strong consistency check of the quenching model. Given that the model implies satellite quenching is rapid and occurs well within R {sub 200}, this would suggest that ram-pressure stripping of either the hot or cold gas component of galaxies are the most plausible candidates for the physical mechanism. The high cold gas consumption rates at z ∼ 1 make it difficult to determine whether hot or cold gas stripping is dominant; however, measurements of the redshift

  13. The Phase Space and Stellar Populations of Cluster Galaxies at z ~ 1: Simultaneous Constraints on the Location and Timescale of Satellite Quenching

    CERN Document Server

    Muzzin, Adam; McGee, Sean L; Balogh, Michael; Franx, Marijn; Hoekstra, Henk; Hudson, Michael J; Noble, Allison; Taranu, Dan; Webb, Tracy; Wilson, Gillian; Yee, H K C

    2014-01-01

    We investigate the velocity vs. position phase space of z ~ 1 cluster galaxies using a set of 424 spectroscopic redshifts in 9 clusters drawn from the GCLASS survey. Dividing the galaxy population into three categories: quiescent, star-forming, and poststarburst, we find that these populations have distinct distributions in phase space. Most striking are the poststarburst galaxies, which are commonly found at small clustercentric radii with high clustercentric velocities, and appear to trace a coherent ``ring" in phase space. Using several zoom simulations of clusters we show that the coherent distribution of the poststarbursts can be reasonably well-reproduced using a simple quenching scenario. Specifically, the phase space is best reproduced if satellite quenching occurs on a rapid timescale (0.1 < tau_{Q} < 0.5 Gyr) after galaxies make their first passage of R ~ 0.5R_{200}, a process that takes a total time of ~ 1 Gyr after first infall. We compare this quenching timescale to the timescale implied by...

  14. Food supplements increase adult tarsus length, but not growth rate, in an island population of house sparrows (Passer domesticus).

    OpenAIRE

    Cleasby, I. R.; Burke, T.; Schroeder, J.; Nakagawa, S.

    2011-01-01

    Abstract Background Variation in food supply during early development can influence growth rate and body size in many species. However, whilst the detrimental effects of food restriction have often been studied in natural populations, how young individuals respond to an artificial increase in food supply is rarely investigated. Here, we investigated both the short-term and long-term effects of providing house sparrow chicks with food supplements during a key period of growth and development a...

  15. Geographic distribution of habitat, development, and population growth rates of the Asian citrus psyllid, Diaphorina citri, in Mexico.

    Science.gov (United States)

    López-Collado, José; Isabel López-Arroyo, J; Robles-García, Pedro L; Márquez-Santos, Magdalena

    2013-01-01

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is an introduced pest in Mexico and a vector of huanglongbing, a lethal citrus disease. Estimations of the habitat distribution and population growth rates of D. citri are required to establish regional and areawide management strategies and can be used as a pest risk analysis tools. In this study, the habitat distribution of D. citri in Mexico was computed with MaxEnt, an inductive, machine-learning program that uses bioclimatic layers and point location data. Geographic distributions of development and population growth rates were determined by fitting a temperature-dependent, nonlinear model and projecting the rates over the target area, using the annual mean temperature as the predictor variable. The results showed that the most suitable regions for habitat of D. citri comprise the Gulf of Mexico states, Yucatán Peninsula, and areas scattered throughout the Pacific coastal states. Less suitable areas occurred in northern and central states. The most important predictor variables were related to temperature. Development and growth rates had a distribution wider than habitat, reaching some of the northern states of México. Habitat, development, and population growth rates were correlated to each other and with the citrus producing area. These relationships indicated that citrus producing states are within the most suitable regions for the occurrence, development, and population growth of D. citri, therefore increasing the risk of huanglongbing dispersion.

  16. Impact climate change factors on the clonal sedge Carex bigelowii. Implications for population growth and vegetative spread

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, B.Aa. (Lund Univ., Dept. of Ecology, Plant Ecology, Lund (Sweden)); Callaghan, T.V. (Univ. of Manchester, Centre for Arctic Biology, School of Biological Sciences, Manchester (United Kingdom))

    1994-12-01

    Hypothesized life-cycle responses to climate change for the arctic, clonal perennial Carex bigelowii are constructed using a range of earlier observations and experiments together with new information from monitoring and an environmental perturbation study. These data suggest, that under current climate change scenarios, increases in CO[sub 2], temperature and nutrient availability would promote growth in a qualitatively similar way. The evidence suggests that both tiller size and daughter tiller production will increase, and be shifted towards production of phalanx tillers which have a greater propensity for flowering. Furthermore, age at tillering as well as tiller life span may decrease, whereas survival of younger age classes might be higher. Mathematical models using experimental data incorporating these hypotheses were used to (a) integrate the various responses and to calculate the order of magnitude of changes in population growth rate ([lambda]), and (b) to explore the implications of responses in individual demographic parameters for population growth rate. The models suggest that population growth rate following climate change might increase significantly, but not unrealistically so, with the younger, larger, guerilla tillers being the most important tiller categories in contributing to [lambda]. The rate of vegetative spread is calculated to more than double, while cyclical trends in flowering and population growth are predicted to decrease substantially. (au) (43 refs.)

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

    Science.gov (United States)

    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.

  18. Population effects of growth hormone transgenic coho salmon depend on food availability and genotype by environment interactions.

    Science.gov (United States)

    Devlin, Robert H; D'Andrade, Mark; Uh, Mitchell; Biagi, Carlo A

    2004-06-22

    Environmental risk assessment of genetically modified organisms requires determination of their fitness and invasiveness relative to conspecifics and other ecosystem members. Cultured growth hormone transgenic coho salmon (Oncorhynchus kisutch) have enhanced feeding capacity and growth, which can result in large enhancements in body size (>7-fold) relative to nontransgenic salmon, but in nature, the ability to compete for available food is a key factor determining survival fitness and invasiveness of a genotype. When transgenic and nontransgenic salmon were cohabitated and competed for different levels of food, transgenic salmon consistently outgrew nontransgenic fish and could affect the growth of nontransgenic cohorts except when food availability was high. When food abundance was low, dominant individuals emerged, invariably transgenic, that directed strong agonistic and cannibalistic behavior to cohorts and dominated the acquisition of limited food resources. When food availability was low, all groups containing transgenic salmon experienced population crashes or complete extinctions, whereas groups containing only nontransgenic salmon had good (72.0 +/- 4.3% SE) survival, and their population biomass continued to increase. Thus, effects of growth hormone transgenic salmon on experimental populations were primarily mediated by an interaction between food availability and population structure. These data, while indicative of forces which may act on natural populations, also underscore the importance of genotype by environment interactions in influencing risk assessment data for genetically modified organisms and suggest that, for species such as salmon which are derived from large complex ecosystems, considerable caution is warranted in applying data from individual studies.

  19. Satellite formation. II

    Science.gov (United States)

    Harris, A. W.

    1978-01-01

    A satellite formation model is extended to include evolution of planetary ring material and elliptic orbital motion. In this model the formation of the moon begins at a later time in the growth of the earth, and a significant fraction of the lunar material is processed through a circumterrestrial debris cloud where volatiles might have been lost. Thus, the chemical differences between the earth and moon are more plausibly accounted for. Satellites of the outer planets probably formed in large numbers throughout the growth of those planets. Because of rapid inward evolution of the orbits of small satellites, the present satellite systems represent only satellites formed in the last few percent of the growths of their primaries. The rings of Saturn and Uranus are most plausibly explained as the debris of satellites disrupted within the Roche limit. Because such a ring would collapse onto the planet in the course of any significant further accretion by the planet, the rings must have formed very near or even after the conclusion of accretion.

  20. Population growth rates of reef sharks with and without fishing on the great barrier reef: robust estimation with multiple models.

    Directory of Open Access Journals (Sweden)

    Mizue Hisano

    Full Text Available Overfishing of sharks is a global concern, with increasing numbers of species threatened by overfishing. For many sharks, both catch rates and underwater visual surveys have been criticized as indices of abundance. In this context, estimation of population trends using individual demographic rates provides an important alternative means of assessing population status. However, such estimates involve uncertainties that must be appropriately characterized to credibly and effectively inform conservation efforts and management. Incorporating uncertainties into population assessment is especially important when key demographic rates are obtained via indirect methods, as is often the case for mortality rates of marine organisms subject to fishing. Here, focusing on two reef shark species on the Great Barrier Reef, Australia, we estimated natural and total mortality rates using several indirect methods, and determined the population growth rates resulting from each. We used bootstrapping to quantify the uncertainty associated with each estimate, and to evaluate the extent of agreement between estimates. Multiple models produced highly concordant natural and total mortality rates, and associated population growth rates, once the uncertainties associated with the individual estimates were taken into account. Consensus estimates of natural and total population growth across multiple models support the hypothesis that these species are declining rapidly due to fishing, in contrast to conclusions previously drawn from catch rate trends. Moreover, quantitative projections of abundance differences on fished versus unfished reefs, based on the population growth rate estimates, are comparable to those found in previous studies using underwater visual surveys. These findings appear to justify management actions to substantially reduce the fishing mortality of reef sharks. They also highlight the potential utility of rigorously characterizing uncertainty, and

  1. Genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population

    Directory of Open Access Journals (Sweden)

    Ana Maria Bezerra Oliveira Lôbo

    2009-01-01

    Full Text Available The genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population were estimated by applying the Average Information Restricted Maximum Likelihood method to an animal model. Data from a flock supported by the Programa de Melhoramento Genético de Caprinos e Ovinos de Corte (GENECOC were used. The traits studied included birth weight (BW, weaning weight (WW, slaughter weight (SW, yearling weight (YW, weight gain from birth to weaning (GBW, weight gain from weaning to slaughter (GWS, weight gain from weaning to yearling (GWY, age at first lambing (AFL, lambing interval (LI, gestation length (GL, lambing date (LD - number of days between the start of breeding season and lambing, litter weight at birth (LWB and litter weight at weaning (LWW. The direct heritabilities were 0.35, 0.81, 0.65, 0.49, 0.20, 0.15 and 0.39 for BW, WW, SW, YW, GBW, GWS and GWY, respectively, and 0.04, 0.06, 0.10, 0.05, 0.15 and 0.11 for AFL, LI, GL, LD, LWB and LWW, respectively. Positive genetic correlations were observed among body weights. In contrast, there was a negative genetic correlation between GBW and GWS (-0.49 and GBW and GWY (-0.56. Positive genetic correlations were observed between AFL and LI, LI and GL, and LWB and LWW. These results indicate a strong maternal influence in this herd and the presence of sufficient genetic variation to allow mass selection for growth traits. Additive effects were of little importance for reproductive traits, and other strategies are necessary to improve the performance of these animals.

  2. Population pharmacokinetic/pharmacodynamic modeling of tumor growth kinetics in medullary thyroid cancer patients receiving cabozantinib.

    Science.gov (United States)

    Miles, Dale R; Wada, David R; Jumbe, Nelson L; Lacy, Steven A; Nguyen, Linh T

    2016-04-01

    Nonlinear mixed effects models were developed to describe the relationship between cabozantinib exposure and target lesion tumor size in a phase III study of patients with progressive metastatic medullary thyroid cancer. These models used cabozantinib exposure estimates from a previously published population pharmacokinetic model for cabozantinib in cancer patients that was updated with data from healthy-volunteer studies. Semi-mechanistic models predict well for tumors with static, increasing, or decreasing growth over time, but they were not considered adequate for predicting tumor sizes in medullary thyroid cancer patients, among whom an early reduction in tumor size was followed by a late stabilization phase in those receiving cabozantinib. A semi-empirical tumor model adequately predicted tumor profiles that were assumed to have a net growth rate constant that was piecewise continuous in the regions of 0-110 and 110-280 days. Emax models relating average concentration to average change in tumor size predicted that an average concentration of 79 and 58 ng/ml, respectively, would yield 50% of the maximum possible tumor reduction during the first 110 days of dosing and during the subsequent 110-280 days of dosing. Simulations of tumor responses showed that daily doses of 60 mg or greater are expected to provide a similar tumor reduction. Both model evaluation of observed data and simulation results suggested that the two protocol-defined cabozantinib dose reductions from 140 to 100 mg/day and from 100 to 60 mg/day are not projected to result in a marked reduction in target lesion regrowth.

  3. Genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population.

    Science.gov (United States)

    Lôbo, Ana Maria Bezerra Oliveira; Lôbo, Raimundo Nonato Braga; Paiva, Samuel Rezende; de Oliveira, Sônia Maria Pinheiro; Facó, Olivardo

    2009-10-01

    The genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population were estimated by applying the Average Information Restricted Maximum Likelihood method to an animal model. Data from a flock supported by the Programa de Melhoramento Genético de Caprinos e Ovinos de Corte (GENECOC) were used. The traits studied included birth weight (BW), weaning weight (WW), slaughter weight (SW), yearling weight (YW), weight gain from birth to weaning (GBW), weight gain from weaning to slaughter (GWS), weight gain from weaning to yearling (GWY), age at first lambing (AFL), lambing interval (LI), gestation length (GL), lambing date (LD - number of days between the start of breeding season and lambing), litter weight at birth (LWB) and litter weight at weaning (LWW). The direct heritabilities were 0.35, 0.81, 0.65, 0.49, 0.20, 0.15 and 0.39 for BW, WW, SW, YW, GBW, GWS and GWY, respectively, and 0.04, 0.06, 0.10, 0.05, 0.15 and 0.11 for AFL, LI, GL, LD, LWB and LWW, respectively. Positive genetic correlations were observed among body weights. In contrast, there was a negative genetic correlation between GBW and GWS (-0.49) and GBW and GWY (-0.56). Positive genetic correlations were observed between AFL and LI, LI and GL, and LWB and LWW. These results indicate a strong maternal influence in this herd and the presence of sufficient genetic variation to allow mass selection for growth traits. Additive effects were of little importance for reproductive traits, and other strategies are necessary to improve the performance of these animals.

  4. Life History Traits and Population Growth of Greenhouse Whitefly (Trialeurodes vaporariorum Westwood on Different Tomato Genotypes

    Directory of Open Access Journals (Sweden)

    Mirjana Prijović

    2013-12-01

    Full Text Available The effects of five tomato genotypes (cv. Narvik and hybrids NS-6, Tamaris, Alliance and Marko on the survival, reproduction, development and population growth of the greenhouse whitefly Trialeurodes vaporariorum were examined. A laboratory population of T. vaporariorum had been reared on tobacco plants for three years before the study. Females that laid eggs on the genotype Marko lived significantly longer and their offspring needed significantly shorter periods to develop than females on the genotype Narvik. The highest gross and net fecundity rates were found in females on the genotype Marko (36.74 eggs/ female and 27.93 eggs/female, respectively and they differed significantly from the corresponding rates of females living on the genotype NS-6 (18.55 eggs/female and 15.33 eggs/ female, who had the lowest fecundity rates. The highest gross and net fertility rates were also found in females on the genotype Marko (31.24 adults/female and 23.73 adults/female, and they were significantly higher than those of females living on NS-6 (14.85 adults/female and 12.53 adults/female. Besides, net fertility rate of the females living on the genotype Narvik (13.80 adults/female was also significantly lower than the rate of females on Marko. The instantaneous rates of increase showed no significant difference over a 10-day interval following the start of oviposition, while the increase rate was significantly higher on the genotype Marko after 12, 14 and 16 days, compared to the genotype NS-6. Eighteen, 20 and 22 days after the beginning of oviposition, the instantaneous rate of increase on the genotype Marko was significantly higher than it was on NS-6 and Narvik. Our data provide a basis for further research aiming to improve programs of integrated management of greenhouse whitefly.

  5. Genetic and environmental factors influencing the Placental Growth Factor (PGF variation in two populations.

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    Rossella Sorice

    Full Text Available Placental Growth Factor (PGF is a key molecule in angiogenesis. Several studies have revealed an important role of PGF primarily in pathological conditions (e.g.: ischaemia, tumour formation, cardiovascular diseases and inflammatory processes suggesting its use as a potential therapeutic agent. However, to date, no information is available regarding the genetics of PGF variability. Furthermore, even though the effect of environmental factors (e.g.: cigarette smoking on angiogenesis has been explored, no data on the influence of these factors on PGF levels have been reported so far. Here we have first investigated PGF variability in two cohorts focusing on non-genetic risk factors: a study sample from two isolated villages in the Cilento region, South Italy (N=871 and a replication sample from the general Danish population (N=1,812. A significant difference in PGF mean levels was found between the two cohorts. However, in both samples, we observed a strong correlation of PGF levels with ageing and sex, men displaying PGF levels significantly higher than women. Interestingly, smoking was also found to influence the trait in the two populations, although differently. We have then focused on genetic risk factors. The association between five single nucleotide polymorphisms (SNPs located in the PGF gene and the plasma levels of the protein was investigated. Two polymorphisms (rs11850328 and rs2268614 were associated with the PGF plasma levels in the Cilento sample and these associations were strongly replicated in the Danish sample. These results, for the first time, support the hypothesis of the presence of genetic and environmental factors influencing PGF plasma variability.

  6. On pitfalls in the construction of family-based models of population growth: a note.

    Science.gov (United States)

    Kondo, H

    1986-04-01

    Recently, several attempts have been made to construct an economic theory of population based on a formal theory of the family of the type developed by Becker in 1981, but there are serious limitations in all such efforts. The typical family's problem may have no solution, even with a well-behaved concave utility function. Moreover, even when the family's maximum problem has a unique solution, the phase diagram for the stock of capital may contain no steady state other than the origin. Finally, even when there exists a nontrivial steady state for the stock of capital, the community nevertheless may be destined for extinction. The first of these pitfalls concerns the internal consistency of the models, while the second and third concern the compatibility of the models with some gross facts of life. The pitfalls can be avoided, within the Becker framework by suitably restricting the family's utility and production functions, but the restrictions required are severe. This paper shows that, alternatively, the pitfalls sometimes can be avoided by going slightly outside the Becker framework, specifically, by modifying the typical family's budget constraint to allow explicitly for the cost of raising children. In particular, it is shown that, by this means, the pitfalls can be avoided even when the famil's utility function is log-linear, the example adduced by Kemp et al. In 1984 to demonstrate the existence of pitfalls. More precisely, it is shown that the family's maximum problem has a unique solution; that nontrival steady state exists; that, even if the steady state is locally unstable, the optimal trajectory tends neither to zero nor to infinity but to a 2-period limit cycle; and that survival is possible with quite general production functions. Thus, the end product is a logically consistent and reasonable model of economic development, with both population growth and capital accumulation firmly rooted in life-cycle family planning.

  7. Variation of growth rate and survival in embryos and larvae of Rana temporaria populations from the Pyrenees

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    Neus Oromi

    2015-12-01

    Full Text Available Variations on embryonic and larval life history traits of ectotherm organisms are strongly affected by temperature conditions. However, these effects can vary between species and populations depending on the mechanisms that act in a determinate local habitat. In the present study, we analysed the effects of temperature on several embryonic and larval traits (survival, development and growth rate until the metamorphosis of Rana temporaria in two populations living at different altitude (1540 and 2100 m in the Pyrenees. Five spawns from each population were distributed in a common garden experiment at different temperature treatments according to the normal temperature range that tadpoles might experience in the field and also considering a high treatment (24 °C to test a possible effect of global warming. Like in other studies of the same species in a latitudinal gradient, the temperature effects depended on the analysed trait. Our results support the general rule that the rate of development is faster at higher temperatures, although survival was significantly affected by the highest temperature in the highland population. Size varied at embryonic and larval stages and was largest at metamorphosis in the highland population. In concordance, the growth rate was higher in the highland population suggesting a countergradient variation in response to the short growing season. However, this possible adaptation can be altered in a global warming scenario with an increase of mortality and limited growth.

  8. Bayesian Reliability-Growth Analysis for Statistical of Diverse Population Based on Non-homogeneous Poisson Process

    Institute of Scientific and Technical Information of China (English)

    MING Zhimao; TAO Junyong; ZHANG Yunan; YI Xiaoshan; CHEN Xun

    2009-01-01

    New armament systems are subjected to the method for dealing with multi-stage system reliability-growth statistical problems of diverse population in order to improve reliability before starting mass production. Aiming at the test process which is high expense and small sample-size in the development of complex system, the specific methods are studied on how to process the statistical information of Bayesian reliability growth regarding diverse populations. Firstly, according to the characteristics of reliability growth during product development, the Bayesian method is used to integrate the testing information of multi-stage and the order relations of distribution parameters. And then a Gamma-Beta prior distribution is proposed based on non-homogeneous Poisson process(NHPP) corresponding to the reliability growth process. The posterior distribution of reliability parameters is obtained regarding different stages of product, and the reliability parameters are evaluated based on the posterior distribution. Finally, Bayesian approach proposed in this paper for multi-stage reliability growth test is applied to the test process which is small sample-size in the astronautics filed. The results of a numerical example show that the presented model can make use of the diverse information synthetically, and pave the way for the application of the Bayesian model for multi-stage reliability growth test evaluation with small sample-size. The method is useful for evaluating multi-stage system reliability and making reliability growth plan rationally.

  9. Hepatocyte growth factor genetic variations and primary angle-closure glaucoma in the Han Chinese population.

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    Zhengxuan Jiang

    Full Text Available PURPOSE: The aim of this study is to examine whether or not hepatocyte growth factor (HGF genetic variations are associated with susceptibility to primary angle-closure glaucoma (PACG in the Han Chinese population. METHODS: Three single-nucleotide polymorphisms (SNPs-rs5745718, rs17427817, and rs3735520-in the HGF gene were genotyped in 238 adult patients with PACG and 287 age-, sex-, and ethnically matched healthy controls by using a polymerase chain reaction restriction fragment length polymorphism assay. Data was analyzed by χ(2 analysis. RESULTS: The three tested analyzed polymorphisms in the HGF gene were in Hardy-Weinberg equilibrium, in all the subjects. The frequencies of the genotype and allele of rs5745718 and rs1742817 in the HGF gene were significantly different between the PACG patients and the controls. On one hand, the frequencies of the CC genotype and C allele of rs5745718 were significantly decreased in PACG patients compared with controls (Pc = 1.40×10(-3; Pc = 3.21×10(-4, respectively; however, on the other hand, significantly decreased frequencies of the GG genotype and the G allele of rs17427817 were observed in PACG patients compared with the controls (Pc = 0.006,; Pc = 6.06×10(-4, respectively. A comparison of the distributions of the genotypes and alleles of rs3735520 showed no statistically significant differences between the PACG patients and the controls (pc>0.05. The haplotype analysis results showed that the CGC haplotype frequency was significantly decreased in the patients with PACG compared with the controls (pc<0.001. No difference was detected between the patients and the controls with regard to the other haplotypes. CONCLUSIONS: Our study suggests that rs5745718 and rs17427817 are associated with a decreased risk of PACG in the Chinese Han population. The CGC haplotype was demonstrated to possibly play a protective role against PACG in this population.

  10. Reconciling dwarf galaxies with LCDM cosmology: Simulating a realistic population of satellites around a Milky Way-mass galaxy

    CERN Document Server

    Wetzel, Andrew R; Kim, Ji-hoon; Faucher-Giguere, Claude-Andre; Keres, Dusan; Quataert, Eliot

    2016-01-01

    Low-mass "dwarf" galaxies represent the most significant challenges to the cold dark matter (CDM) model of cosmological structure formation. Because these faint galaxies are (best) observed within the Local Group of the Milky Way (MW) and Andromeda (M31), understanding their formation in such an environment is critical. We present the first results from the Latte Project: the Milky Way on FIRE (Feedback in Realistic Environments). This simulation models the formation of a MW-mass galaxy to z = 0 within LCDM cosmology, including dark matter, gas, and stars at unprecedented resolution: baryon mass of 7070 M_sun at spatial resolution down to 1 pc. Latte was simulated using the GIZMO code with a mesh-free method for accurate hydrodynamics and the FIRE model for star formation and explicit feedback within a multi-phase interstellar medium. For the first time, Latte self-consistently resolves the internal structure of dwarf galaxies that form around a MW-mass host down to M_star > 10^5 M_sun. Latte's population of ...

  11. Population Growth, Climate Change and Water Scarcity in the Southwestern United States.

    Science.gov (United States)

    Fuller, Amy C; Harhay, Michael O

    2010-06-30

    PROBLEM STATEMENT: In a simple economic model, water scarcity arises as a result of an imbalance between the supply of and demand for water sources. Distribution in this setting is the source of numerous conflicts globally. APPROACH: Already, the Southwestern United States (US) suffers from annual drought and long-standing feud over natural water resources. RESULTS: Population growth in the Southwestern United States along with the continued effects of climate change (natural and anthropogenic) predicts a perpetual decline in natural water sources, such as smaller snowpacks, in the coming years. As the increasing number of communities across multiple US states that subsist off of natural water supplies face water shortages with increasing severity, further water conflict will emerge. Such conflicts become especially protracted when the diversion of water from a source of benefit to one community negatively impacts nearby communities of humans and economically vital ecosystems (e.g., marshlands or tributaries). CONCLUSION/RECOMMENDATIONS: The ensuing politics and health effects of these diversions can be complicated and future water policies both domestically and internationally are lacking. To draw attention to and stimulate discussion around the lacking policy discussion domestically, herein we document existing and emerging consequences of watery scarcity in the Southwestern United States and briefly outline past and potential future policy responses.

  12. Population Growth, Climate Change and Water Scarcity in the Southwestern United States

    Directory of Open Access Journals (Sweden)

    Amy c. Fuller

    2010-01-01

    Full Text Available Problem statement: In a simple economic model, water scarcity arises as a result of an imbalance between the supply of and demand for water sources. Distribution in this setting is the source of numerous conflicts globally. Approach: Already, the Southwestern United States (US suffers from annual drought and long-standing feud over natural water resources. Results: Population growth in the Southwestern United States along with the continued effects of climate change (natural and anthropogenic predicts a perpetual decline in natural water sources, such as smaller snowpacks, in the coming years. As the increasing number of communities across multiple US states that subsist off of natural water supplies face water shortages with increasing severity, further water conflict will emerge. Such conflicts become especially protracted when the diversion of water from a source of benefit to one community negatively impacts nearby communities of humans and economically vital ecosystems (e.g., marshlands or tributaries. Conclusion/Recommendations: The ensuing politics and health effects of these diversions can be complicated and future water policies both domestically and internationally are lacking. To draw attention to and stimulate discussion around the lacking policy discussion domestically, herein we document existing and emerging consequences of watery scarcity in the Southwestern United States and briefly outline past and potential future policy responses.

  13. Vascular endothelial growth factor gene polymorphisms in age-related macular degeneration in a Turkish population

    Institute of Scientific and Technical Information of China (English)

    Yunus; Bulgu; Gokhan; Ozan; Cetin; Vildan; Caner; Ebru; Nevin; Cetin; Volkan; Yaylali; Cem; Yildirim

    2014-01-01

    AIM:To assess the association between age-related macular degeneration(AMD) and three single nucleotide polymorphisms(SNPS) related to the vascular endothelial growth factor(VEGF) gene.METHODS:The patients who were diagnosed with AMD were included in this prospective study. Three SNPs(rs1413711, rs2146323, and rs3025033) of the VEGF gene were genotyped by real-time polymerase chain reaction in the genomic DNA isolated from peripheral blood samples of the 82 patients and 80 controls.RESULTS:The genotype frequencies of rs1413711 and rs2146323 were not significantly different between the study group and the control group(P =0.072 and P =0.058).However, there was a significant difference in the genotype frequencies of these SNPs between the wet type AMD and dry type AMD(P =0.005 and P =0.010,respectively). One of the SNPs(rs1413711) was also found to be associated with the severity of AMD(P =0.001)with significant genotype distribution between early,intermediate, and advanced stages of the disease. The ancestral alleles were protective for both SNPs while the polymorphic alleles increased the risk for dry AMD.CONCLUSION:VEGF SNPs rs1413711 and rs2146323 polymorphisms are significantly associated with AMD subtypes in our population.

  14. Biology of the amphioxus, Branchiostoma belcheri in the Ariake Sea, Japan I. Population structure and growth.

    Science.gov (United States)

    Henmi, Yasuhisa; Yamaguchi, Takao

    2003-07-01

    We investigated the population structure and growth of the amphioxus Branchiostoma belcheri for four years in the southern Ariake Sea, Japan. We counted 62-66 myotomes and 251-310 dorsal fin-ray chambers, and these results support that this species is an intermediate form of B. belcheri and its subspecies B. belcheri tsingtauense. The ratio of females to males was 1:1.12. Males were more numerous than females among small individuals (< 40 mm body length), but we found no significant differences among large animals (50 mm body length). Spawning occurred from mid June to early July. Groups of newly settled young appeared from January to June of their second year. We observed a large fluctuation between years in the numbers of newly settled young. The estimated size of one-year-old individuals was 19.4 mm in body length; within the next 12 months, they reached 32.1 mm. Three- and four-year-old individuals measured 38.6 mm and 45.8 mm, respectively. Few grew beyond 60 mm; the largest specimen collected was a 64 mm male.

  15. [Contraception as an instrument against population growth: expert discussions and the public sphere in 1960s West Germany].

    Science.gov (United States)

    Silies, Eva-Maria

    2010-09-01

    Theoretically, the introduction of the contraceptive pill in the 1960s created new possibilities to control population growth on a global scale. Several of those involved in developing the pill belonged to the transnational population control movement. In the Federal Republic, demographic and medical experts in the 1960s debated the advantages and dangers of the new contraceptive, and they argued about whether it could be of benefit in West Germany and/or in developing countries. The paper examines the contemporary debate about the pill and the role it was awarded in the effort to solve what was considered a global population problem.

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

    Science.gov (United States)

    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 bulls, particularly those with heterozygous GH genotypes.

  17. Investigating behaviour and population dynamics of striped marlin (Kajikia audax from the southwest Pacific Ocean with satellite tags.

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    Tim Sippel

    Full Text Available Behaviour and distribution of striped marlin within the southwest Pacific Ocean were investigated using electronic tagging data collected from 2005-2008. A continuous-time correlated random-walk Kalman filter was used to integrate double-tagging data exhibiting variable error structures into movement trajectories composed of regular time-steps. This state-space trajectory integration approach improved longitude and latitude error distributions by 38.5 km and 22.2 km respectively. Using these trajectories as inputs, a behavioural classification model was developed to infer when, and where, 'transiting' and 'area-restricted' (ARB pseudo-behavioural states occurred. ARB tended to occur at shallower depths (108 ± 49 m than did transiting behaviours (127 ± 57 m. A 16 day post-release period of diminished ARB activity suggests that patterns of behaviour were affected by the capture and/or tagging events, implying that tagged animals may exhibit atypical behaviour upon release. The striped marlin in this study dove deeper and spent greater time at ≥ 200 m depth than those in the central and eastern Pacific Ocean. As marlin reached tropical latitudes (20-21 °S they consistently reversed directions, increased swimming speed and shifted to transiting behaviour. Reversals in the tropics also coincided with increases in swimming depth, including increased time ≥ 250 m. Our research provides enhanced understanding of the behavioural ecology of striped marlin. This has implications for the effectiveness of spatially explicit population models and we demonstrate the need to consider geographic variation when standardizing CPUE by depth, and provide data to inform natural and recreational fishing mortality parameters.

  18. Long-term effect of temperature and precipitation on radial growth in a threatened thermo-Mediterranean tree population

    OpenAIRE

    2016-01-01

    The combined effect of climate change and habitat destruction and fragmentation threatens many plant populations and even entire communities in Mediterranean ecosystems. The Iberian pear, Pyrus bourgaeana Decne, a characteristic species of Mediterranean ecosystems, is threatened by both habitat and climate changes. We ask whether and how the growth of mature P. bourgaeana in the thermo-Mediterranean zone (i.e., altitude

  19. Southern (DisComfort?: Latino Population Growth, Economic Integration and Spatial Assimilation in North Carolina Micropolitan Areas

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    Ana-María González Wahl

    2007-10-01

    Full Text Available This paper examines more closely the growth and assimilation of the Latino population in non-metropolitan areas across North Carolina. More specifically, the analysis focuses on micropolitan areas. Based on the last decennial census, micropolitan areas were newly defined by the Census Bureau to reflect the growing importance of "urban clusters" located in non-metropolitan counties.

  20. Population differentiation and the effects of herbivory and sand compaction on the subterranean growth of a desert lily.

    Science.gov (United States)

    Ruiz-R, Natalia; Ward, David; Saltz, David

    2006-01-01

    Differences in level of herbivory can select for local adaptation and genetic differentiation of plant populations in different environments. Mean bulb depth of the desert lily Pancratium sickenbergeri, differs considerably among populations differing in the level of herbivory by the dorcas gazelle. The gazelle digs in the sand to remove most of the bulb of the lily. Deeper bulbs have less material removed by herbivory than shallow bulbs and have higher fitness. A possible confounding factor is the degree of sand compaction, which may retard the downward growth of the bulb. We conducted a common garden experiment with 2 sand types with seeds from source populations with different levels of herbivory. There was a large genetic difference among populations. Two of 3 analyses indicated that there was an interaction between population and sand type, indicating that there is a heritable component of plasticity.

  1. Long-term data reveal a population decline of the tropical lizard Anolis apletophallus, and a negative affect of el nino years on population growth rate.

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    Jessica Stapley

    Full Text Available Climate change threatens biodiversity worldwide, however predicting how particular species will respond is difficult because climate varies spatially, complex factors regulate population abundance, and species vary in their susceptibility to climate change. Studies need to incorporate these factors with long-term data in order to link climate change to population abundance. We used 40 years of lizard abundance data and local climate data from Barro Colorado Island to ask how climate, total lizard abundance and cohort-specific abundance have changed over time, and how total and cohort-specific abundance relate to climate variables including those predicted to make the species vulnerable to climate change (i.e. temperatures exceeding preferred body temperature. We documented a decrease in lizard abundance over the last 40 years, and changes in the local climate. Population growth rate was related to the previous years' southern oscillation index; increasing following cooler-wetter, la niña