Science.gov

Sample records for 1990s population growth

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

    ERIC Educational Resources Information Center

    Perry, Marc

    2002-01-01

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

  2. Public Education: A Major American Growth Industry in the 1990's.

    ERIC Educational Resources Information Center

    Ehrenhalt, Samuel M.

    Public education has been a major growth industry in the 1990s, expanding its employment by nearly 24 percent from 1988 to 1998. The 1.8 million jobs added in state and local government education functions placed this sector third among America's growth industries in the sheer magnitude of its employment rise. This report examines the record of…

  3. Changes in Land Surface Water Dynamics since the 1990s and Relation to Population Pressure

    NASA Technical Reports Server (NTRS)

    Prigent, C.; Papa, F.; Aires, F.; Jimenez, C.; Rossow, W. B.; Matthews, E.

    2012-01-01

    We developed a remote sensing approach based on multi-satellite observations, which provides an unprecedented estimate of monthly distribution and area of land-surface open water over the whole globe. Results for 1993 to 2007 exhibit a large seasonal and inter-annual variability of the inundation extent with an overall decline in global average maximum inundated area of 6% during the fifteen-year period, primarily in tropical and subtropical South America and South Asia. The largest declines of open water are found where large increases in population have occurred over the last two decades, suggesting a global scale effect of human activities on continental surface freshwater: denser population can impact local hydrology by reducing freshwater extent, by draining marshes and wetlands, and by increasing water withdrawals. Citation: Prigent, C., F. Papa, F. Aires, C. Jimenez, W. B. Rossow, and E. Matthews (2012), Changes in land surface water dynamics since the 1990s and relation to population pressure, in section 4, insisting on the potential applications of the wetland dataset.

  4. Civil Rights Movement and the 1990s: Racism and the African-American Population.

    ERIC Educational Resources Information Center

    Czech, Christopher

    A plan is presented for a curriculum that shows how African Americans have been left out of decision making, stereotyped negatively, and denied resources. The project is intended to be a base for future studies of human relations issues in order to understand how society operates. Using the contexts of the 1960s and the 1990s, the power structures…

  5. Growth, Distribution, and Poverty in Africa: Messages from the 1990s. Poverty Dynamics in Africa.

    ERIC Educational Resources Information Center

    Christiaensen, Luc; Demery, Lionel; Paternostro, Stefano

    This book reviews trends in household well-being in Africa during the 1990s. Using the better data sets now available, the main factors behind observed poverty changes are examined in eight countries: Ethiopia, Ghana, Madagascar, Mauritania, Nigeria, Uganda, Zambia, and Zimbabwe. A broad view of poverty is taken, which includes income poverty and…

  6. U.S. Hispanics: Challenging Issues for the 1990s. Population Trends and Public Policy, Number 17.

    ERIC Educational Resources Information Center

    Valdivieso, Rafael; Davis, Cary

    The number of Hispanics in the United States reached 20 million in 1988, a 34% increase since 1980, reflecting growth that challenges U.S. policymakers in nearly every area, but most urgently in education, job training, and welfare. There is considerable diversity within the U.S. Hispanic community, but Mexicans, Puerto Ricans, Cubans, and other…

  7. Revised Birth and Fertility Rates for the 1990s and New Rates for Hispanic Populations, 2000 and 2001: United States.

    ERIC Educational Resources Information Center

    Hamilton, Brady E.; Sutton, Paul D.; Ventura, Stephanie J.

    2003-01-01

    This report presents revised birth and fertility rates for 1991-1999, plus previously published rates for 2000-2001, based on populations consistent with the April 1, 2000 census. Revised rates for Hispanic subgroups are also included. Rates are presented by age, race, and Hispanic origin of mother; by age, race, Hispanic origin, and marital…

  8. Pattern of declining blood pressure across replicate population surveys of the WHO MONICA project, mid-1980s to mid-1990s, and the role of medication

    PubMed Central

    Tunstall-Pedoe, Hugh; Connaghan, John; Woodward, Mark; Tolonen, Hanna; Kuulasmaa, Kari

    2006-01-01

    Objective Declining mean systolic and diastolic blood pressures were observed in most populations of the World Health Organization MONICA (monitoring trends and determinants in cardiovascular disease) project from the mid-1980s to mid-1990s. We tested whether pooled results would show mean change associated with decline in high readings only, resulting from better antihypertensive medication, or with similar falls in low, middle, and high readings, implying other causes. Design Independent, random sample, cross sectional population surveys, each end of the MONICA decade. Setting 38 populations in 21 countries across four continents. Participants Design target in each survey of 200 participants in each 10 year age and sex group from age 35 to 64 Main outcome measures Changes in the population in mean systolic and diastolic blood pressure, and in low, middle, and high readings—the 20th, 50th, and 80th centiles—and the differences between these changes. Results Individual populations differed considerably, but pooling the 38 population results gave mean changes in systolic blood pressure of -2.2 mm Hg in men, -3.3 mm Hg in women, and in diastolic blood pressure of -1.4 mm Hg in men and -2.2 mm Hg in women (overall average -2.26 mm Hg, population median -1.55 mm Hg). Antihypertensive medication, associated with high readings, rose by 0.5% to 11.4%. However, average falls in low and middle blood pressure readings were so similar to those in high readings and in the mean that no effect from improving treatment of hypertension was detected. Results in contrasted subgroups were consistent. Conclusions Blood pressure fell across 38 MONICA populations at all levels of readings, with no differential fall in high readings attributable to better control of hypertension. Despite the importance of medication to individuals, in that decade other determinants of blood pressure lowering must have been more pervasive and powerful in whole populations. PMID:16531419

  9. Simulating Population Growth.

    ERIC Educational Resources Information Center

    Byington, Scott

    1997-01-01

    Presents a strategy to help students grasp the important implications of population growth. Involves an interactive demonstration that allows students to experience exponential and logistic population growth followed by a discussion of the implications of population-growth principles. (JRH)

  10. [Population Growth and Development].

    ERIC Educational Resources Information Center

    Clausen, A. W.

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

  11. Strategies for the 1990s.

    ERIC Educational Resources Information Center

    Chaffee, Ellen Earle

    1990-01-01

    Eight strategies are recommended to higher education in the 1990s including committing to improving quality; stressing customer service; increasing use of data and analysis in management; developing data on outcomes issues, processes, and behaviors; and working cooperatively with elementary and secondary education. (MLW)

  12. Population growth and economic growth.

    PubMed

    Narayana, D L

    1984-01-01

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

  13. Impact of Population Growth

    ERIC Educational Resources Information Center

    Ehrlich, Paul R.; Holdren, John P.

    1971-01-01

    Discusses the interrelated crises in population growth, natural resources, and environmental quality. Major problems include population control, redirection of technology, closed resource cycles, equitable opportunity distribution and prosperity. Population growth is regarded as causing a disportionate world-wide negative environmental impact.…

  14. Modeling Exponential Population Growth

    ERIC Educational Resources Information Center

    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…

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

    ERIC Educational Resources Information Center

    Newman, Constance

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

  16. Teaching about Population Growth.

    ERIC Educational Resources Information Center

    Otero, George G., Jr., Comp.

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

  17. Disaggregated analysis of US energy consumption in the 1990s: Evidence of the effects of the internet and rapid economic growth

    SciTech Connect

    Murtishaw, Scott; Schipper, Lee

    2001-07-01

    This paper decomposes US energy use from 1988 to 1998 and attributes the changes in energy use to three underlying factors: activity, structure, and intensity. For this study we use a bottom-up methodology, by separately decomposing delivered energy use in six sectors: travel, freight, manufacturing industries, non-manufacturing industries, residential, and services. The most commonly used indicator of energy efficiency in the total economy, the ratio of energy consumed to unit of GDP (E/GDP) created can often be misleading. The rapid decline in the E/GDP ratio in recent years has been used to support assertions that the Internet and information technologies in general have enabled improvements in energy efficiencies. However, our disaggregate analysis suggests that energy intensities on average are falling more slowly than ever before while actual energy use increased faster than at any time since 1970. The decline in the E/GDP ratio in the mid-to late 1990s owes much more to structural changes in the demand for energy services than to falling energy intensities.

  18. Packet switching in 1990's

    NASA Astrophysics Data System (ADS)

    Rybczynski, A.

    The author assesses wide-area networking end-user needs as they evolve into the 1990s. He then turns to the network operator environment, both public and private, by examining service evolution trends. The author concludes with an assessment of how packet switching services and technologies are evolving to continue to match the identified market requirements, with specific emphasis on Northern Telecom's DPN Data Networking System. Key evolving DPN capabilities include the introduction of the high-end DPN100 30-kb/s switch, a variety of access options including ISDN (integrated services digital network) packet mode services, higher throughput virtual circuits, megabit trunking for improved network throughput and end-user transit delay, and SNA session switching, the latter being an example of adding value to packet networking through communication processing.

  19. Population growth and consumption.

    PubMed

    Chalkley, K

    1997-04-01

    The relationship between population growth, resource consumption, and environmental degradation is complex. The rise in "greenhouse gases" that will cause climatic change is clearly due to human activity, and pollutants are often concentrated in densely populated areas. However, even an area with a negative population growth, such as Russia, can experience severe environmental degradation due to poor management. Consumption patterns have the most effect on ozone depletion, while population growth threatens biodiversity of and within species through the destruction of ecosystems. Migration joins population growth and social factors, such as land inequality, as major causes of deforestation, and global demand for water is expected to increase faster than the rate of population growth. Coastal development and over-fishing threaten to deplete the oceans, while soil quality is threatened by inappropriate land use. Estimates of the earth's carrying capacity range from less than 3 billion to more than 44 billion people, indicating how difficult it is to assess this figure. Development efforts throughout the world may lead to human gains that will ultimately be negated by environmental losses. These factors have led to growing support for environmentally sustainable development. PMID:12319715

  20. Global population growth.

    PubMed

    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

  1. [Poverty and population growth].

    PubMed

    1983-07-01

    In the mid-1970s, some 120 million Latin Americans were unable to satisfy their most basic material needs. 55 million of them were in extreme indigency, unable to satisfy their minimal food needs even by using their entire incomes for that purpose. The rapid rate of demographic growth in Latin America influences the growth of the poor strata, who in absolute and relative terms show the highest rates of population growth. Despite heterogeneity in the manifestations of poverty, the poor have certain traits in common: employment outside the modern sector, with low productivity and little hope of generating stable incomes, low consumption capability, and lack of political power. 1 of the great problems of economic development in Latin America is the exclusion of the poorest strata from employment in better paid jobs. The high rate of fertility and rapid population growth provoke a negative interaction between population and development, in which the poorest strata reproduce most rapidly, becoming even poorer. A program of family planning within a development effort providing employment and income is needed to mitigate the problem, and no avenue or effort of implementation should be neglected on ideological grounds. Between 1960-70, the share of the poorest 20% of the population declined from 3.1% to 2.5% of the toal income of the region, while that of the poorest 1/2 increased slightly from 13.4% to 13.9%. In 1970 the poorest 20% had a per capita income of about US $70/year. It has been estimated that the proportion of the poor in Latin America declined from 51% in 1960 to 40% in 1970 and 33% at present, but the absolute number of persons affected continues to increase. PMID:12339314

  2. Law Library Service in the 1990's.

    ERIC Educational Resources Information Center

    The Bookmark, 1990

    1990-01-01

    This issue of "The Bookmark" presents 20 articles focusing on various aspects of law library services in New York State. The articles are: (1) "Law Library Services in the 1990's" (Christine Bain); (2) "A Librarian's View of Legal Publishing Today" (Margaret Maes Axtmann); (3) "Legal Publishing--A Publisher's View" (Kenneth Lee Halajian); (4)…

  3. Family Research in the 1990s.

    ERIC Educational Resources Information Center

    Parke, Ross D.

    Theories about, methods of studying, and definitions of family have undergone profound shifts over the last several decades, and change continues to characterize developmental research on family functioning. In the 1990s, researchers have recognized the need for more descriptive studies as well as more process-oriented work. Research is beginning…

  4. Retirement Age Declines Again in 1990s.

    ERIC Educational Resources Information Center

    Gendell, Murray

    2001-01-01

    The average retirement age continued to decline in the 1990s after having leveled off during the preceding 10-15 years. The resumption of the decline is attributed largely to a rise in the labor force participation rate of older men and women between the mid-1980s and 2000. (Author/JOW)

  5. National security in the 1990s

    SciTech Connect

    Rich, M.D.

    1991-02-01

    The Rand Paper contains the text of a speech given at a luncheon co-sponsored by Town Hall of California and the Los Angeles Council of Engineers and Scientists on national security affairs in the 1990s. The speech was given at the Biltmore Hotel, Los Angeles, California, on February 19, 1991.

  6. Depository Libraries in the 1990s.

    ERIC Educational Resources Information Center

    Garner, Diane

    The assumption is made that what the 1990s have in store for users of depository libraries will hinge on three crucial areas: (1) the reform and development of government information policies; (2) changing technology; and (3) the willingness and ability of the depository libraries to accommodate these changes. The uncertain role of the government…

  7. Population Growth: Crisis and Challenge.

    ERIC Educational Resources Information Center

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

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

  8. U.S. Population Growth.

    ERIC Educational Resources Information Center

    Dillner, Harry

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

  9. Population Growth: Stretching the Limits.

    ERIC Educational Resources Information Center

    Brouse, Deborah E.

    1990-01-01

    Three population education activities that can be used to illustrate the effects of uncontrolled population growth are presented. Included are "Crowding Can Be Seedy," which uses seeds; "Something for Everyone," which illustrates competition for resources; and "More or Less," which illustrates the relationship between humans and the environment.…

  10. Enterprise storage report for the 1990's

    NASA Technical Reports Server (NTRS)

    Moore, Fred

    1991-01-01

    Data processing has become an increasingly vital function, if not the most vital function, in most businesses today. No longer only a mainframe domain, the data processing enterprise also includes the midrange and workstation platforms, either local or remote. This expanded view of the enterprise has encouraged more and more businesses to take a strategic, long-range view of information management rather than the short-term tactical approaches of the past. Some of the significant aspects of data storage in the enterprise for the 1990's are highlighted.

  11. Enterprise storage report for the 1990's

    NASA Technical Reports Server (NTRS)

    Moore, Fred

    1992-01-01

    Data processing has become an increasingly vital function, if not the most vital function, in most businesses today. No longer only a mainframe domain, the data processing enterprise also includes the midrange and workstation platforms, either local or remote. This expanded view of the enterprise has encouraged more and more businesses to take a strategic, long-range view of information management rather than the short-term tactical approaches of the past. This paper will highlight some of the significant aspects of data storage in the enterprise for the 1990's.

  12. Macroeconomic adjustment, food availability and nutrition status in Nigeria. A look at the 1990s.

    PubMed

    Igbedioh, S O

    1990-12-01

    Faced with balance of payment problems, declining commodity prices, and a corresponding reduction in foreign exchange earnings, Nigeria implemented a structural adjustment program in 1986. This step was taken in response to encouragement from the International Monetary Fund and the World Bank, and was aimed to accomplish the following: find the true value of the official currency; overcome public sector inefficiency through improved public expenditure and parastatal rationalization; reschedule medium- and long-term debt to relieve debt burden; and encourage net foreign capital inflow while limiting foreign loans. Implementing and adhering to these macroeconomic adjustment policies has brought unprecedented inflation, lower real earnings, and increased malnutrition among lower income sectors of the population. The poor have suffered diminishing access to nutritious foods. Conscribed access to food and compromised nutritional status will most likely persist into the 1990s unless corrective policies are adopted. Appropriate policy would aim to increase the poor's access to food and limit population growth. PMID:12285940

  13. Canada's population: growth and dualism.

    PubMed

    Beaujot, R P

    1978-04-01

    In Canada the current 1.3% population growth rate is causing some concern. Those concerned argue that such a rate of growth in combination with high levels of consumption could jeopardize the country's resource base and its comfortable style of living. Many Canadians are questioning high levels of immigration, for now that the fertility level is below replacement level, net immigration contributes substantially to population growth (over 1/3 in 1976). The growing proportion of non-Europeans among recent immigrants is causing resentment, and, in a tight job market, immigrants are regarded as threats to the World War 2 baby boom cohort who are now at working ages. The baby boom generation also puts stress on housing and health services, and it will increase the need for pension checks as it ages. Although French fertility is no longer high and immigration is no longer dominated by the British, the French group's 200-year struggle to preserve its identity continues on in the current effort of the Quebec government to enforce the use of French language by law within that province. Geography and climate dictate another demographic fact that divides the country and pervades its history. In addition to intense regionalism, uneven population distribution is responsible for 2 other concerns: the rapid growth of several already large cities and depopulation of many small communities. Focus in this discussion is on Canada's population growth in the past and as projected for the future, historical and current fertility, mortality and immigration trends, the search for a new immigration policy, the impact of the baby boom generation on the population's age structure and the problems this creates, and recent shifts in population distribution and in the country's ethnic and linguistic makeup. The population policy proposals evolved thus far involve to a great extent the use of immigration as a lever for achieving given population objectives. PMID:12335577

  14. Patterns of growth and body condition in sea otters from the Aleutian archipelago before and after the recent population decline

    USGS Publications Warehouse

    Laidre, K.L.; Estes, J.A.; Tinker, M.T.; Bodkin, J.; Monson, D.; Schneider, K.

    2006-01-01

    3In addition to larger asymptotic values for mass and length, the rate of growth towards asymptotic values was more rapid in the 1990s than in the 1960s/70s: sea otters reached 95% of asymptotic body mass and body length 1–2 years earlier in the 1990s.4Body condition (as measured by the log mass/log length ratio) was significantly greater in males than in females. There was also an increasing trend from the 1960s/70s through 2004 despite much year-to-year variation.5Population age structures differed significantly between the 1960s/70s and the 1990s with the latter distribution skewed toward younger age classes (indicating an altered lxfunction) suggesting almost complete relaxation of age-dependent mortality patterns (i.e. those typical of food-limited populations).6This study spanned a period of time over which the population status of sea otters in the Aleutian archipelago declined precipitously from levels at or near equilibrium densities at some islands in the 1960s/70s to < 5% of estimated carrying capacity by the late 1990s. The results of this study indicate an improved overall health of sea otters over the period of decline and suggest that limited nutritional resources were not the cause of the observed reduced population abundance. Our findings are consistent with the hypothesis that the decline was caused by increased killer whale predation.

  15. Explosive Welding in the 1990's

    NASA Technical Reports Server (NTRS)

    Lalwaney, N. S.; Linse, V. D.

    1985-01-01

    Explosive bonding is a unique joining process with the serious potential to produce composite materials capable of fulfilling many of the high performance materials capable of fulfilling many of the high performance materials needs of the 1990's. The process has the technological versatility to provide a true high quality metallurgical compatible and incompatible systems. Metals routinely explosively bonded include a wide variety of combinations of reactive and refractory metals, low and high density metals and their alloys, corrosion resistant and high strength alloys, and common steels. The major advantage of the process is its ability to custom design and engineer composites with physical and/or mechanical properties that meet a specific or unusual performance requirement. Explosive bonding offers the designer unique opportunities in materials selection with unique combinations of properties and high integrity bonds that cannot be achieved by any other metal joining process. The process and some applications are discussed.

  16. Infrared zoom lenses in the 1990s

    NASA Astrophysics Data System (ADS)

    Mann, Allen

    1994-01-01

    The breadth of activity in the field of IR zoom lenses is international in scope. Representative IR zoom lens systems of the 1990s from the continents of North America, Europe, and Asia and the Middle East are presented. Design considerations unique to the IR spectrum such as athermalization are given special attention. The various approaches to solving these design problems are described along with the operating characteristics of these systems. Applications include forward-looking IR scanning systems and target simulators. Tolerance considerations during manufacture are presented. Innovative reflective zoom systems are also considered. Development trends for the next several years are discussed, including the use of diffractive optical elements in IR zoom lens systems.

  17. Physics through the 1990s: An overview

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The volume details the interaction of physics and society, and presents a short summary of the progress in the major fields of physics and a summary of the other seven volumes of the Physics through the 1990s series, issues and recommended policy changes are described regarding funding, education, industry participation, small-group university research and large facility programs, government agency programs, and computer database needs. Three supplements report in detail on international issues in physics (the US position in the field, international cooperation and competition-especially on large projects, freedom for scientists, free flow of information, and education of foreign students), the education and supply of physicists (the changes in US physics education, employment and manpower, and demographics of the field), and the organization and support of physics (government, university, and industry research; facilities; national laboratories; and decision making). An executive summary contains recommendations for maintaining excellence in physics. A glossary of scientific terms is appended.

  18. Physics through the 1990s: an overview

    SciTech Connect

    Not Available

    1986-01-01

    The volume details the interaction of physics and society, and presents a short summary of the progress in the major fields of physics and a summary of the other seven volumes of the Physics through the 1990s series. Issues and recommended policy changes are described regarding funding, education, industry participation, small-group university research and large facility programs, government agency programs, and computer database needs. Three supplements report in detail on international issues in physics (the US position in the field, international cooperation and competition--especially on large projects, freedom for scientists, free flow of information, and education of foreign students), the education and supply of physicists (the changes in US physics education, employment and manpower, and demographics of the field), and the organization and support of physics (government, university, and industry research; facilities; national laboratories; and decision making). An executive summary contains recommendations for maintaining excellence in physics. A glossary of scientific terms is appended.

  19. Physics through the 1990s: An overview

    NASA Astrophysics Data System (ADS)

    The volume details the interaction of physics and society, and presents a short summary of the progress in the major fields of physics and a summary of the other seven volumes of the Physics through the 1990s series, issues and recommended policy changes are described regarding funding, education, industry participation, small-group university research and large facility programs, government agency programs, and computer database needs. Three supplements report in detail on international issues in physics (the US position in the field, international cooperation and competition-especially on large projects, freedom for scientists, free flow of information, and education of foreign students), the education and supply of physicists (the changes in US physics education, employment and manpower, and demographics of the field), and the organization and support of physics (government, university, and industry research; facilities; national laboratories; and decision making). An executive summary contains recommendations for maintaining excellence in physics. A glossary of scientific terms is appended.

  20. Modeling Population Growth and Extinction

    ERIC Educational Resources Information Center

    Gordon, Sheldon P.

    2009-01-01

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

  1. Population Growth: Family Planning Programs.

    ERIC Educational Resources Information Center

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

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

  2. Nutrition, Development, and Population Growth

    ERIC Educational Resources Information Center

    Berg, Alan

    1973-01-01

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

  3. Political economy of population growth.

    PubMed

    Mehta, S; Mehta, H S

    1987-01-01

    Tracing the origin of political economy as a class-science, this paper focuses on the political economy of population growth. Exposing the limitations of Malthusian ideas and their invalidity even for the capitalist economies, it discusses the subsequent revival of the Malthusian model during the period of de-colonization and the misinterpretation of the relationship between population growth and development in the developing and developed countries. Taking India, China, and Japan as some case studies, the paper examines the relationship between birth rate levels and some correlates. It elaborates on the Indian experience, emphasizing the association of population growth with poverty and unemployment and lays bare some of the hidden causes of these phenomena. The authors examine some interstate variations in India and identify constraints and prospects of the existing population policy. The paper proposes outlines of a democratic population policy as an integral part of India's development strategy which should recognize human beings not simply as consumers but also as producers of material values. It pleads for 1) restructuring of property relations; 2) bringing down the mortality rates and raising of the literacy levels, especially among females; and 3) improving nutritional levels, as prerequisites for bringing down birth rates. PMID:12179026

  4. Anomalous Growth of Aging Populations

    NASA Astrophysics Data System (ADS)

    Grebenkov, Denis S.

    2016-04-01

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

  5. Environmental impact of population growth

    NASA Astrophysics Data System (ADS)

    Naylor, Rosamond; Matson, Pamela

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

  6. Population growth can be checked.

    PubMed

    Shukla, J P

    Since independence, India's population size has doubled. The rate of growth was 2.5% during 1971-81, an increase from the rate of 2.15% observed during the 1951-61 period. The increase indicated that efforts to decrease population growth have not succeeded. The implications with respect to food, housing, clothing, education, and health facilities, which are fundamental to improving the physical quality of life, are severe. This demographic trend is a serious impediment to progress. The population growth is due to a constant birthrate and a sharp decline in mortality. Reducing the birthrate is necessary to reduce the rate of growth. An attitudinal change adopting the norm of family limitation should be encouraged through propaganda, socioeconomic programs, and religious and cultural organizations. Other measures to bring about a decline in the birthrate include: increasing the marriage age, and expanding educational and employment opportunities for women and girls. These measures will require substantial effort and time. Incentives may show more immediate effects. Monetary incentives are not desired because of the possibility of misuse. However the government could assume responsibility for the education and guarantee employment of children of couples who have only one child, and provide free education to children of couples with only 2 children. These incentives are not likely to be misused, can be available to all segments of the population, and involve no immediate large financial burden on the government. In addition, scholarships to the Harijan students should be limited to 2 per family. If these measures are accepted, they could quickly reduce the birth rate. PMID:12311944

  7. Human Population: Fundamentals of Growth and Change.

    ERIC Educational Resources Information Center

    Stauffer, Cheryl Lynn, Ed.

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

  8. [Population growth and the environment].

    PubMed

    Hogan, D J

    1991-01-01

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

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

    PubMed

    Greenspan, A

    1994-12-01

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

  10. NASA scientific and technical information for the 1990s

    NASA Technical Reports Server (NTRS)

    Cotter, Gladys A.

    1990-01-01

    Projections for NASA scientific and technical information (STI) in the 1990s are outlined. NASA STI for the 1990s will maintain a quality bibliographic and full-text database, emphasizing electronic input and products supplemented by networked access to a wide variety of sources, particularly numeric databases.

  11. Nonmetro Poverty: Assessing the Effect of the 1990s.

    ERIC Educational Resources Information Center

    Jolliffe, Dean

    2003-01-01

    During the 1990s, the poverty rate in nonmetropolitan areas declined to a record low of 13.4 percent. Drawing on census data, aspects of nonmetro poverty during the 1990s are outlined, including effects of urbanization, regional differences, racial and ethnic differences, importance of family structure, needs for assistance and human services,…

  12. Patterns of dynamic urban population growth in Russia, 1989-1996: a research report.

    PubMed

    Rowland, R H

    1997-01-01

    "The purpose of this paper is to investigate locations in which rapid urban growth occurred in Russia over the period 1989 to 1996....Particular emphasis will be given to the geographical patterns, economic functions, and population size of rapidly growing towns. In addition, the discussion of trends for 1989-1996 also will be briefly preceded by and compared to those of 1979-1989, although the paper will emphasize trends during the 1990s. Furthermore, the topic of ¿new towns', which themselves often are rapidly growing centers, will be addressed as well." PMID:12292848

  13. Into the Video Age: Open University Television in the 1990s.

    ERIC Educational Resources Information Center

    Kirkwood, Adrian

    1990-01-01

    Discussion of developments in British television broadcasting that affect educational television focuses on Open University television productions. Topics discussed include advantages of broadcasting for distance education; growth in the use of video cassettes; current access to video equipment; and possible future developments for the 1990s.…

  14. Migration, population growth, and development.

    PubMed

    1983-01-01

    In the 30 years between 1950 and 1980, the population of the developing world almost doubled--from 1.7 to 3.3 billion. Among the most conspicuous signs of this increase are the growth of cities and, in some areas, international labor migration. Since 1950 the cities in Africa, Asia, and Latin America have been growing more than twice as fast as those in North America and Europe. Some of the biggest cities are growing fastest--by as much as 8 percent each year. At this rate they will double in less than a decade. About 40 percent of this growth is due to migration and 60 percent to the children born in the cities to natives and the newly arrived migrants. Altogether, about one billion people (1,000 million) now live in developing-country cities, where fewer than 300 million lived in 1950. About 15 to 20 million workers, mostly from developing countries, are now international migrants. About half travel to Europe and the US, the rest to other developing countries. Many of the migrants, especially to the US, Europe, or the Middle East, want to bring their families eventually and settle permanently. Migration to African destinations is more likely to be temporary or seasonal, while Latin American and Asian patterns are mixed. Policy makers in developing countries are voicing concern about the highly visible social, economic, and political problems created by rapid urbanization and by large-scale international labor migration. While governments have tried a variety of policies to influence population distribution, most have been limited in scope and had little success. As long as birth rates remain high in some areas and large differences in wages exist between jobs in different places, most of these policies have little hope of stopping or reversing long-term trends. Family planning programs, although they do not create immediate jobs or higher wages in rural areas, can help to reduce the high birth rates that produce an ever-increasing supply of potential migrants

  15. Alternative Teaching Strategies for the 1990s.

    ERIC Educational Resources Information Center

    Gloeckner, Gene W.; And Others

    This paper is intended to assist teachers in examining and altering their own teaching practices and in transforming the classroom from a place of "dull sameness" to an environment where excitement reigns and student growth is at the forefront. The teaching strategies outlined were chosen for three criteria: active student involvement,…

  16. World Food Prospects for the 1990s.

    ERIC Educational Resources Information Center

    Tarrant, John R.

    1990-01-01

    Addresses world hunger issues and the increasing world population. Sees continued imbalance between supply and demand. Points out Europe and the United States are dealing with surplus production, whereas developing nations continue to import needed food. Argues solving hunger problems requires eliminating poverty through development programs.…

  17. Population growth rates: issues and an application.

    PubMed Central

    Godfray, H Charles J; Rees, Mark

    2002-01-01

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

  18. The Bellagio Declaration: overcoming hunger in the 1990's.

    PubMed

    Alloo, F; Arizpe, L; Belford, T S; Clark, J; Csanadi, J; Davies, P J; Emmerij, L; George, S; Hyden, G; Jonsson, U

    1989-01-01

    In November 1989, 23 leading hunger experts met in Bellagio, Italy, issues a document called the "Bellagio Declaration: Overcoming Hunger in the 1990s." The report lists 4 achievable goals: eliminate famine deaths; end hunger in half of the world's poorest households; reduce by half malnutrition of mothers and small children; and eradicate iodine and vitamin A deficiencies. Famine deaths can be eliminated by setting up early-warning systems and longer-term relief objectives. The only remaining obstacle is how to prevent warring nations from blocking food deliveries and destroying food. Hunger can be eliminated in half the world's poor households by giving the poor access to resources and credit, rehabilitating degraded ecosystems, using sustainable farming, and using existing markets to distribute food equitably. Malnutrition can be halved by sustained breastfeeding, and supplementation of food and micronutrients. Iodine and vitamin A deficiencies can be eliminated by giving iodized oil injections, vitamin A capsules and iodized salt. Ways of dealing with obstacles such as population, deforestation, soil and water shortages, pollution, global warming and capital deficits in the South are discussed. There is hope that these goals can be attained because of the outbreak of peace and democracy, freeing up substantial portions of the 1 trillion US dollars spent on defense; abatement of feat of worldwide economic collapse; and evolution of a worldwide logistic system to provide emergency food aid. PMID:12343252

  19. Hispanic Population Growth and Rural Income Inequality

    ERIC Educational Resources Information Center

    Parrado, Emilio A.; Kandel, William A.

    2010-01-01

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

  20. U.S. Hispanics: challenging issues for the 1990s.

    PubMed

    Valdivieso, R; Davis, C

    1988-12-01

    Hispanics are the largest minority in the US after blacks and, as a poor and disadvantaged minority, face many problems and challenges with which they must deal in the future. There has been a 34% increase in the US Hispanic population from 1980-1988 due to heavy immigration and high birth rates, resulting in a young age structure for Latinos with a median age of 25.5 years vs. the US median of 32.2 years. US Latinos are a very diverse group which includes Mexicans (62%), Puerto Ricans (13%), Cubans (5%), and Central and South Americans (12%), although they tend to be clustered in very few states. Discrimination has plagued this population because of illegal immigration concerns and illegal drug flow problems. Hispanics continue to suffer from poor educational achievement, language barriers, low-paying jobs, and poverty. Cubans have made the most progress so far in all of these areas. Poverty will likely persist into the 1990's. Bilingualism is and will be prevalent as long as immigration continues, but future generations will begin to use English as their 1st language. 17 states, however, have adopted "official English" laws in order to decrease the use of funds for Spanish language services. Using Spanish in school is a very divided issue--some favor bilingual education, some favor the shot-gun English approach. As Hispanics grow into work force age, lack of education will prevent entry into skilled labor. Corporations, however, are taking a bigger interest in bilingual workers. Nationally, Hispanics are beginning to matter as an electorate. The number of Latino elected officials has doubled from 1974 to 1988. The 1990 census may show us that we have been underestimating the number of Hispanics in the US. A higher percentage of future Latin immigrants will be better educated. Policymakers should recognize Hispanic problems and help to promote solutions, in the interest of the American people as a whole. PMID:12315691

  1. Decline of subpolar North Atlantic circulation during the 1990s.

    PubMed

    Häkkinen, Sirpa; Rhines, Peter B

    2004-04-23

    Observations of sea surface height reveal that substantial changes have occurred over the past decade in the mid- to high-latitude North Atlantic Ocean. TOPEX/Poseidon altimeter data show that subpolar sea surface height increased during the 1990s, and the geostrophic velocity derived from altimeter data exhibits declining subpolar gyre circulation. Combining the data from earlier satellites, we find that subpolar circulation may have been weaker in the late 1990s than in the late 1970s and 1980s. Direct current-meter observations in the boundary current of the Labrador Sea support the weakening circulation trend of the 1990s and, together with hydrographic data, show that the mid- to late 1990s decline extends deep in the water column. Analysis of the local surface forcing suggests that the 1990s buoyancy forcing has a dynamic effect consistent with altimetric and hydrographic observations: A weak thermohaline forcing allows the decay of the domed structure of subpolar isopycnals and weakening of circulation. PMID:15087505

  2. The Growth of the Black Metropolitan Population.

    ERIC Educational Resources Information Center

    Taeuber, Conrad; Mosher, William T.

    The urbanization of the black population is a relatively recent phenomenon. Historically, migration has been the major source of the growth of the black population in the large cities of the North, yet the migration from nonmetropolitan to metropolitan areas has been going long enough to have established a substantial black population in the…

  3. Analysis of residential, industrial and commercial sector responses to potential electricity supply constraints in the 1990s

    SciTech Connect

    Fisher, Z.J.; Fang, J.M.; Lyke, A.J.; Krudener, J.R.

    1986-09-01

    There is considerable debate over the ability of electric generation capacity to meet the growing needs of the US economy in the 1990s. This study provides new perspective on that debate and examines the possibility of power outages resulting from electricity supply constraints. Previous studies have focused on electricity supply growth, demand growth, and on the linkages between electricity and economic growth. This study assumes the occurrence of electricity supply shortfalls in the 1990s and examines the steps that homeowners, businesses, manufacturers, and other electricity users might take in response to electricity outages.

  4. Global environmental security: Research and policy strategies for the 1990s

    SciTech Connect

    Lazaro, M.A.; Wang, Hua.

    1992-01-01

    The subject of global environmental change is emerging as one of the most hotly debated international issues for the 1990s. In fact, our earth system has undergone a nature-induced gradual change in climate on both a temporal scale that spans over millions of years and a spatial scale ranging from regional to transcontinental. Pollutant emissions associated with population growth and industrial activities manifest the anthropogenic climatic forcing that has been superimposed on the background of natural climate fluctuations. Our incomplete understanding of the global impacts of environmental pollution on the earth systems (atmosphere, biosphere, hydrosphere, cryosphere, and lithosphere), however, make the prediction of the timing, magnitude, and patterns of future global change uncertain. This paper examines the science and policy background of global environmental change. The major scientific uncertainties and policy issues confronting decision makers are identified; and the scientific framework, as well as current national and international research programs aimed at resolving the scientific uncertainties, are discussed. A coherent, stable, and flexible policy is needed to provide a foundation for coordinated international-interagency programs of observation, research, analysis, and international negotiation toward a policy consensus concerning global environmental security. On the basis of what is currently known about global change, recommendations are presented on both near-term and long-term policy option decisions.

  5. Global environmental security: Research and policy strategies for the 1990s

    SciTech Connect

    Lazaro, M.A.; Wang, Hua

    1992-09-01

    The subject of global environmental change is emerging as one of the most hotly debated international issues for the 1990s. In fact, our earth system has undergone a nature-induced gradual change in climate on both a temporal scale that spans over millions of years and a spatial scale ranging from regional to transcontinental. Pollutant emissions associated with population growth and industrial activities manifest the anthropogenic climatic forcing that has been superimposed on the background of natural climate fluctuations. Our incomplete understanding of the global impacts of environmental pollution on the earth systems (atmosphere, biosphere, hydrosphere, cryosphere, and lithosphere), however, make the prediction of the timing, magnitude, and patterns of future global change uncertain. This paper examines the science and policy background of global environmental change. The major scientific uncertainties and policy issues confronting decision makers are identified; and the scientific framework, as well as current national and international research programs aimed at resolving the scientific uncertainties, are discussed. A coherent, stable, and flexible policy is needed to provide a foundation for coordinated international-interagency programs of observation, research, analysis, and international negotiation toward a policy consensus concerning global environmental security. On the basis of what is currently known about global change, recommendations are presented on both near-term and long-term policy option decisions.

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

    PubMed

    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

  7. Financing American Higher Education in the 1990s.

    ERIC Educational Resources Information Center

    Hauptman, Arthur M.

    1997-01-01

    Reviews major issues in the financing of higher education in the 1990s, including overall resource level, revenue patterns (state and local financial commitment, federal funding, student charges, endowment income and private giving), and the changing role of student aid. Also examines issues as they affect different sectors or institution types.…

  8. Education and Inequalities in Rural Vietnam in the 1990s

    ERIC Educational Resources Information Center

    Belanger, Daniele; Liu, Jianye

    2008-01-01

    This article examines the determinants of children's schooling during the 1990s in rural areas of Vietnam. It focuses on the impact of family attributes on the likelihood of children remaining in school or leaving during the primary and secondary school years. Using data from the Vietnam Living Standard Survey (VLSS) of 1992-93 and 1997-98, the…

  9. Preparing Schools for the 1990s: An Essay Collection.

    ERIC Educational Resources Information Center

    Metropolitan Life Foundation.

    Education has emerged as a leading national issue for the 1990s. To address some of the current and future issues facing education, Metropolitan Life Insurance Company asked members of the Metropolitan Life Foundation Education Advisory Council to articulate their views about recent and future directions in public-school-improvement efforts. This…

  10. Changing Contexts for Counselor Preparation in the 1990s.

    ERIC Educational Resources Information Center

    Hackney, Harold, Ed.

    The five chapters in this monograph provide guidelines for counselors in the 1990s who will be faced with such societal issues as substance abuse, Acquired Immune Deficiency Syndrome (AIDS), teenage pregnancy, youth unemployment, homelessness, crime and delinquency, and school dropouts. "The Contemporary Counselor in a Changed World" (Harold…

  11. Prospects for Physics in the 1990's Surveyed.

    ERIC Educational Resources Information Center

    Robinson, Arthur L.

    1986-01-01

    A National Academy of Science report ("Physics Through the 1990's") says that American physics has been a highly diversified and productive enterprise, but continued excellence cannot be taken for granted. Progress in six subfields (elementary particle, nuclear, condensed-matter, atomic/molecular, plasma/fluid, and gravitation/cosmology physics)…

  12. Education in the 1990's: A Demographic View.

    ERIC Educational Resources Information Center

    Garcia, Ernest F.

    Since 1975, the United States has experienced the largest wave of immigration since the beginning of the century. This demographic fact holds important implications for education in the 1990s. First, because the birthrate among recent immigrants is relatively high, an increasing number of first generation Americans will enter the school system. As…

  13. Child Poverty Was Lower at End of 1990s.

    ERIC Educational Resources Information Center

    Rogers, Carolyn C.

    2001-01-01

    Poverty rates increased in the early 1990s, but between 1994 and 1999 the metro child poverty rate declined 6 percentage points and the nonmetro rate declined 4 percent. In 1999, the poverty rate for nonmetro Black children was about double that of nonmetro White children, but the Black-White gap in poverty narrowed between 1985 and 1999. (TD)

  14. English Loanwords in the 1990's in Japan.

    ERIC Educational Resources Information Center

    Nakagawa, Akira

    A sociolinguistic analysis of English loan words in use in the 1990s in the discourse of young Japanese people is presented. The study drew data from a 1993 survey of undergraduate students at two Osaka (Japan) higher education institutions, one for men and one for women, which asked what loanwords students used and heard often. The report first…

  15. Transpersonal Social Work: A Theory for the 1990s.

    ERIC Educational Resources Information Center

    Cowley, Au-Deane S.

    1993-01-01

    Notes that transpersonal psychology contains growing body of literature and theory related to spiritual dimension of human nature and higher states of consciousness. Sees this approach as especially relevant for social work practitioners who are combating social ills of 1990s that manifest as violence, addiction, and spiritual malaise. (Author/NB)

  16. Shakespeare for the 1990s: A Multicultural Tempest.

    ERIC Educational Resources Information Center

    Carey-Webb, Allen

    1993-01-01

    Argues that William Shakespeare's "The Tempest" is the play that is best suited for the high school English curriculum of the 1990s. Discusses historical and critical aspects the play's key themes. Shows ways of using the play in high school classes, and describes 19 works to read alongside of"The Tempest." (HB)

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

    PubMed Central

    Turner, Adair

    2009-01-01

    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. PMID:19770149

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

    PubMed

    Turner, Adair

    2009-10-27

    Rapid population growth continues in the least developed countries. The revisionist case that rapid population could be overcome by technology, that population density was advantageous, that capital shallowing is not a vital concern and that empirical investigations had not proved a correlation between high population growth and low per capita income was both empirically and theoretically flawed. In the modern world, population density does not play the role it did in nineteenth-century Europe and rates of growth in some of today's least developed nations are four times than those in nineteenth-century Europe, and without major accumulation of capital per capita, no major economy has or is likely to make the low- to middle-income transition. Though not sufficient, capital accumulation for growth is absolutely essential to economic growth. While there are good reasons for objecting to the enforced nature of the Chinese one-child policy, we should not underestimate the positive impact which that policy has almost certainly had and will have over the next several decades on Chinese economic performance. And a valid reticence about telling developing countries that they must contain fertility should not lead us to underestimate the severely adverse impact of high fertility rates on the economic performance and prospects of many countries in Africa and the Middle East. PMID:19770149

  19. Population growth and environmental degradation in Malawi.

    PubMed

    Kalipeni, E

    1992-01-01

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

  20. Population Growth Types in India, 1961-71

    ERIC Educational Resources Information Center

    Chakravarti, A. K.

    1976-01-01

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

  1. Five proposals re China's population growth control.

    PubMed

    Liu, Z; Wu, C; Lin, F

    1983-01-01

    China's population was 540 million in 1949. By the end of 1978 the population will reach 960 million, representing a 2% average annual growth rate. High population growth 1) is costly, 2) makes finding employment difficult, since there is little still land still to be reclaimed and agricultural productivity cannot be upgraded if backward farming techniques are used simply to employ more people, and 3) reduces the quality of material and cutural life. Nearly half of consumer funds accumulated in 1949-1977 was spent to provide basic needs for China's 600 million people. Housing has especially suffered: average per capita living space is only 2 square meters in some cities. With over 100 million primary school children and tens of millions in secondary schools, education funds must be allocated to the lower grades, to higher education's detriment. Each generation's age structure determines the next generation's reproduction scale and speed. This historical principle leads to the following: 1) population growth will continue to be vigorous given growth at a 2% rate, or if a percentage of rural (30%) and urban (10%) couples continue to have more than 2 children, or if every couple only has 2 children; 2) population stagnation requires continuous, persistent efforts, abolishing 2 or more children and encouraging one child per couple. Stagnation can be reached by 2008, with 1,200 million people. Political and ideological education combined with effective economic measures must solve the population problem. 5 strong measures must be taken: 1) economic policies and incentives should assist couples with one or no child, 2) every means should be used to communicate the population problem to the people, 3) population control should be part of the national economy program, 4) 3 births should be prohibited and one child per couple advocated, and 5) a permanent "population committee" should be established to insure ongoing population programs, policies, study, and evaluation

  2. Improved zircon iron corals for the 1990s

    SciTech Connect

    Decker, C. )

    1992-03-01

    CIBA-GEIGY/Drakenfeld Colors is dedicated to the research and development of consistent and cost-effective ceramic stains for the whitewares industry. After identifying the trends in color for the 1990s. CIBA-GEIGY/Drakenfeld Colors initiated an extensive R D project to improve zircon ion corals for the whitewares industry. These color trends indicated a need for stronger and cleaner zircon iron corals. This paper discusses the chemistry and crystal structure of zircon iron corals. A historical review of Drakenfeld corals will also be presented. The most recent development in Drakenfeld corals will then be compared to other commercially available zircon iron corals. Taking into consideration these comparisons, conclusions will be drawn suggesting the coral of choice for the 1990s.

  3. Vietnam's campaign to reduce population growth.

    PubMed

    Haub, C

    1999-10-01

    This paper reports campaigns to reduce the population growth in Vietnam. In July, red banners flew above the broad boulevard in Hanoi proclaiming World Population Day. This widespread public attention to population issues is not surprising, given the country's sharp reduction in fertility and widespread citizen support for smaller families. Since 1961, Vietnam has been trying to formulate a policy to reduce the population rate growth. The policy was a reaction to the results of the 1960 Census of the Democratic Republic of Vietnam and reflected long-standing concerns over food shortages, as well as a desire to improve women's health and welfare. After the reunification in 1975, the policy was extended to the entire country. Since then, Vietnam's growth rate has been declining, suggesting that the national campaign for smaller families is succeeding in changing deeply held attitudes and perceptions, in addition to current practices. While the fertility decline in Vietnam may not be the world's fastest, the success of the national population policy has forever altered the country's prospect for population growth. PMID:12295331

  4. Teaching the Vietnam War in the 1990s.

    ERIC Educational Resources Information Center

    Franklin, H. Bruce

    For an instructor who has been teaching the Vietnam War for over 30 years, the War has been teaching him for even longer. One of the objectives in teaching the Vietnam War in the 1990s is what it meant to teach the Vietnam War in the 1960s. It is easy to forget that the antiwar movement began as an attempt to educate the government and the nation,…

  5. Flux-vector splitting for the 1990s

    NASA Technical Reports Server (NTRS)

    Vanleer, Bram

    1991-01-01

    The development of flux-vector splitting through the 1970s and 1980s is reviewed. Attention is given to the diffusive nature of flux-vector splitting, which makes it an undesirable technique for approximating the inviscid fluxes in a Navier-Stokes solver. Several proposed improvements, including a brand new one, are discussed and illustrated by a simple, yet revealing, numerical test case. Finally, an outlook for flux-vector splitting in the 1990s is presented.

  6. European satellite in the late 1990's - A BT view

    NASA Astrophysics Data System (ADS)

    Reed, Antony G.

    The use of mobile satellite services, broadcasting satellite services (including TV distribution services in the FSS bands), and fixed satellite sevices to meet the telecommunications needs of the 1990s is considered. Fixed service satellites can cover low-traffic areas and can handle peak overloads of links in different time zones. Developmental needs have been identified in such areas as 16 Kbits/s encoding with speech interpolation, low-cost satellite business system ground terminals, and multichannel echo control devices.

  7. Student Borrowing in the 1990s. ACE Issue Brief.

    ERIC Educational Resources Information Center

    American Council on Education, Washington, DC. Center for Policy Analysis.

    This brief discusses student borrowing to pay for college in the 1990s. Between 1990 and 2000, student loan volume more than doubled in real terms from $16.4 billion to $37.5 billion, and the number of loans made annually also more than doubled, from 4.5 million to 9.4 million. Data, primarily from the National Postsecondary Student Aid Study,…

  8. How Population Growth Affects Linkage Disequilibrium

    PubMed Central

    Rogers, Alan R.

    2014-01-01

    The “LD curve” relates the linkage disequilibrium (LD) between pairs of nucleotide sites to the distance that separates them along the chromosome. The shape of this curve reflects natural selection, admixture between populations, and the history of population size. This article derives new results about the last of these effects. When a population expands in size, the LD curve grows steeper, and this effect is especially pronounced following a bottleneck in population size. When a population shrinks, the LD curve rises but remains relatively flat. As LD converges toward a new equilibrium, its time path may not be monotonic. Following an episode of growth, for example, it declines to a low value before rising toward the new equilibrium. These changes happen at different rates for different LD statistics. They are especially slow for estimates of σd2, which therefore allow inferences about ancient population history. For the human population of Europe, these results suggest a history of population growth. PMID:24907258

  9. Population growth and sustainable development in China.

    PubMed

    Gui, S

    1998-12-01

    This article identifies the adverse impacts of population growth in China and offers suggestions for attaining sustainable development. Although China has below replacement level fertility, population will continue to increase. Chinese demographers project that the total fertility rate will average 2.1 each year until 2010, 2.1 until 2050, or 1.88 until 2010 and 1.6 during 2010-2050 under high, medium, and low variants, respectively. Total population would number 1.69 billion, 1.50 billion, or 1.46 billion under various projections, respectively, by 2050. Continued growth is expected to seriously slow economic development, to hinder improvements in the quality of and full use of human resources, to depress increases in per-capita economic development levels, and to impact on reasonable use of resources and environmental protection. The averting of 5 million births would save 35.5 billion yuan. Population growth has reduced the per-capita share of cultivated land from 0.19 to 0.08 hectares during 1952-95. There are about 150-190 million surplus rural laborers. Registered unemployment in cities was 3.1% in 1997. 11.5 million were laid-off workers. The working-age population will exceed 900 million during 2007-26. China's gross national product (GNP) was the 8th highest in the world in 1990, but its per-capita GNP was in 100th place. China's abundant natural resources are seriously reduced when population is considered. Environmental damage is already evident. Population growth needs to be controlled through family planning, an old-age social security program, and long-term population policies. Society needs healthier births and childbearing and better educated children. PMID:12321930

  10. Determinants of Police Strength in Large U.S. Cities during the 1990s: A Fixed-Effects Panel Analysis

    ERIC Educational Resources Information Center

    McCarty, William P.; Ren, Ling; Zhao, Jihong

    2012-01-01

    The 1990s represented a unique decade in which to analyze the determinants of police strength in the United States. This decade was a time in which crime initially increased, then substantially decreased. Furthermore, this decade also was characterized by increases in the minority population throughout large American cities. Finally, the 1990s…

  11. An analysis of characteristics for change in night light distribution from 1980 s to 1990 s by the time series global dmsp mosaic data

    NASA Astrophysics Data System (ADS)

    Nakayama, Y.; Tanaka, S.; Mitsugi, R.

    The Defense Meteorological Satellite Program (DMSP) Operation Linescan System (OLS) data observing night light distribution on the earth's surface have been archived since the 1970's. The major light distribution on the earth detected by the OLS sensorthe city lights, the forest fire, burning of shifting cultivation, the flame of the gas combustion in the oil fields and the fishing fire of boats due to human activities. In this study, a global DMSP/OLS mosaic data set on the latter half in the 1990's which can be compared with a global DMSP/OLS mosaic one in the 1980's was newly produced after the processing for radiometric and geometric corrections to several OLS original data. Next, the characteristics of night lights distribution and their change in about 10 years from the 1980's to the 1990's were analyzed in detail through the comparison of two global mosaic data on the 1980's and the latter half in the 1990's. Some satellite images in the daytime, geographical information data and the other auxiliary sources were used for the analysis of the change situation of night lights distribution. Finally, the relationship between changes in night light distribution and situation of human activities of the world were discussed. The analysis results clearly showed the expansion of light distribution pattern in several big cities due to the increase of energy consumption depending on the population growth. And, changes in the geographical distribution of the lights from biomass burning by the development of agricultural land and the shifting cultivation due to the increase of population could be grasped evidently.

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

    USGS Publications Warehouse

    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. On the theory of global population growth

    NASA Astrophysics Data System (ADS)

    Kapitza, Sergei P.

    2010-12-01

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

  14. Comparison of logistic equations for population growth.

    PubMed

    Jensen, A L

    1975-12-01

    Two different forms of the logistic equation for population growth appear in the ecological literature. In the form of the logistic equation that appears in recent ecology textbooks the parameters are the instantaneous rate of natural increase per individual and the carrying capacity of the environment. In the form of the logistic equation that appears in some older literature the parameters are the instantaneous birth rate per individual and the carrying capacity. The decision whether to use one form or the other depends on which form of the equation is biologically more realistic. In this study the form of the logistic equation in which the instantaneous birth rate per individual is a parameter is shown to be more realistic in terms of the birth and death processes of population growth. Application of the logistic equation to calculate yield from an exploited fish population also shows that the parameters must be the instantaneous birth rate per individual and the carrying capacity. PMID:1203427

  15. Impact of demographic policy on population growth.

    PubMed

    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

  16. 1990s bright for post-OPEC Ecuador

    SciTech Connect

    Not Available

    1993-03-01

    Ecuador, in its first full year outside the fold of the Organization of Petroleum Exporting Countries, stands poised for a significant expansion of production in the 1990s. While preparing for Ecuador's eventual withdrawal from OPEC last fall, the government since early summer 1992 has moved quickly to approve a number of key development projects. It was, perhaps, no coincidence that the most important conference on Ecuadorian petroleum prospects in recent years was timed to coincide with the government's public confirmation of the pullout. All foreign companies operating in Ecuador attended, with details disclosed of projects planned or under way. This article summarizes these projects and other key issues raised at the conference.

  17. Helioseismology in the 1980s and 1990s

    NASA Astrophysics Data System (ADS)

    Goode, Philip R.

    2014-02-01

    Over more than twenty years, Wojtek Dziembowski and I collaborated on nearly fifty papers, which were concentrated in helioseismology through the 1980s and 1990s, but extended early into the new century. In this review, I discuss the most significant results of this collaboration and some of the underlying sociology that contributed to the intensity and longevity of our collaboration. Our work began with placing limits on the Sun's buried magnetic field and ended with extracting from the solar-cycle dependent oscillation frequency changes the roles (and net result) of competing dynamical drivers of changes in the solar diameter.

  18. The macroeconomic effects of immigration: Israel in the 1990s.

    PubMed

    Beenstock, M; Fisher, J

    1997-01-01

    "In this paper we try to quantify the contribution of immigration to the Israeli economy during the early 1990s. In doing so we consider the effects of immigration on key macroeconomic variables such as GDP, investment, consumption, the labor market, imports, exports and the housing market....A base-run simulation is prepared for 1990-1994 assuming actual immigration. Thereafter a counterfactual simulation is prepared assuming a reduction in immigration; the difference between the two simulations estimates the contribution of immigration to the relevant endogenous variables." PMID:12293419

  19. Riparian-wetland initiative for the 1990`s

    SciTech Connect

    1990-09-01

    This Riparian-Wetland Initiative for the 1990`s provides a blueprint for management and restoration of those areas encompassing 23.7 million acres of BLM lands. This strategy complements other plans such as Waterfowl Habitat Management on Public Lands, A Strategy for the Future and other interdisciplinary, multi-program, cooeprative efforts. Four goals have been established: to restore and maintain riparian-wetland areas so that 75% or more are in proper functioning condition by 1997, to protect areas through proper land management to avoid or mitigate negative impacts, to ensure an aggressive information program, and to improve partnerships and cooperative restorative and management processes.

  20. Physics through the 1990s: Condensed-matter physics

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The volume presents the current status of condensed-matter physics from developments since the 1970s to opportunities in the 1990s. Topics include electronic structure, vibrational properties, critical phenomena and phase transitions, magnetism, semiconductors, defects and diffusion, surfaces and interfaces, low-temperature physics, liquid-state physics, polymers, nonlinear dynamics, instabilities, and chaos. Appendices cover the connections between condensed-matter physics and applications of national interest, new experimental techniques and materials, laser spectroscopy, and national facilities for condensed-matter physics research. The needs of the research community regarding support for individual researchers and for national facilities are presented, as are recommendations for improved government-academic-industrial relations.

  1. Simulation of population growth and structure of the population

    NASA Astrophysics Data System (ADS)

    Maksymowicz, A. Z.

    2002-08-01

    A computer study of population growth and biological ageing in the Penna model is presented. The stress is put on the analysis of the age structure and the distribution of 'bad' mutations m in the population. Results of computer simulation are compared with the simplest logistic model approach which ignores genetic contribution to the life game and accounts only for death due to limited environmental capacity, the Verhulst factor. The Penna model accounts also for genetic load and results of the simulation show that the final population essentially consists of the fittest individuals, as is expected. A more detailed analysis of the genome structure Δ( m) discloses significant marks of the history. The main conclusions are: (a) there is a clear correlation between population n, age a and the number m of bad mutations and (b) there is no correlation between particular configurations Δ( m) of genomes of the same m and the fraction of the population of this characteristics Δ( m). A typical run takes a couple of hours on an HP EXEMPLAR machine, and for a population of about n=10 6.

  2. Stochastic dynamics and logistic population growth.

    PubMed

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

    2015-06-01

    The Verhulst model is probably the best known macroscopic rate equation in population ecology. It depends on two parameters, the intrinsic growth rate and the carrying capacity. These parameters can be estimated for different populations and are related to the reproductive fitness and the competition for limited resources, respectively. We investigate analytically and numerically the simplest possible microscopic scenarios that give rise to the logistic equation in the deterministic mean-field limit. We provide a definition of the two parameters of the Verhulst equation in terms of microscopic parameters. In addition, we derive the conditions for extinction or persistence of the population by employing either the momentum-space spectral theory or the real-space Wentzel-Kramers-Brillouin approximation to determine the probability distribution function and the mean time to extinction of the population. Our analytical results agree well with numerical simulations. PMID:26172687

  3. Stochastic dynamics and logistic population growth

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  4. Design issues for population growth models

    PubMed Central

    López Fidalgo, J.; Ortiz Rodríguez, I.M.

    2010-01-01

    We briefly review and discuss design issues for population growth and decline models. We then use a flexible growth and decline model as an illustrative example and apply optimal design theory to find optimal sampling times for estimating model parameters, specific parameters and interesting functions of the model parameters for the model with two real applications. Robustness properties of the optimal designs are investigated when nominal values or the model is mis-specified, and also under a different optimality criterion. To facilitate use of optimal design ideas in practice, we also introduce a website for generating a variety of optimal designs for popular models from different disciplines. PMID:21647244

  5. Trends in exclusive breastfeeding: findings from the 1990s.

    PubMed

    Labbok, Miriam H; Wardlaw, Tessa; Blanc, Ann; Clark, David; Terreri, Nancy

    2006-08-01

    This article presents trends and differentials in exclusive breastfeeding patterns that occurred in developing settings during the 1990s and considers these trends in relation to the breastfeeding-support activities in that decade. Between 1990 and 2000, the data suggest that exclusive breast-feeding levels in the developing world increased 15% overall among infants younger than 4 months (from 46% to 53%) and among infants older than 6 months (from 34% to 39%). The increase in urban areas is of special note. Urban areas are presumed to be most susceptible to the ambient health system and social and commercial pressures against breastfeeding; the support activities of the 1990s (eg, the Baby-friendly Hospital Initiative and the International Code of Marketing of Breastmilk Substitutes) were developed to address these pressures. Given this, implementation of the Global Strategy for Infant and Young Child Feeding, which supports these proven interventions, should be effective in further increasing optimal breast-feeding practices. PMID:16885487

  6. Rural population growth and living conditions.

    PubMed

    Li, N; Zhu, C

    1991-01-01

    The problem of the effect of population growth on subsistence conditions is addressed by developing generalized premises, principles, and methods for quantifying standards or conditions for growth. This method is applied to 1989 data for Nanzheng Country, China. Background information is provided on an experiment made public in 1985 and implemented in 1986 by the Family Planning (FP) Department of Nanzheng County of Shaanxi Province in Hongmiao District in which the following conditions were placed on bearing a second child: 1) income must be 20% higher than the average village income level, and breeders must have an average income of not 400 yuan/year, crop planters not 300 yuan/year, textile weavers not 200 yuan/year, and industrial and subsidiary production workers not 400 yuan/year (generally 4 pigs or 100 chickens or ducks) or 2) 100 income-producing trees must be planted around he residential area/family plot or stony fields must be transformed into arable land under the contract responsibility system, or groves, orchards, or tea plantations must be planted. These conditions must be met one year prior to proposing to have a second child. The approval rate in 1986-88 was 88.7%, and the second parity rate was 78.4%. Deteriorated conditions had not yet occurred in this country when this proposal was made. The premises considered important in preparing assistance conditions were determined. 1) Conditions for population growth should be resolved within the area. 2) Subsistence conditions should be taken care of by the family. 3) There should be a centralized standard, not a family standard, such that living conditions/capita should not decrease because of population growth. Quantification is made expressing the relationship between subsistence and growth. The application of these conditions for households in Hongmiao District is that the average subsistence conditions need to be higher than other households by 12.3% for new population growth. The assumption is

  7. ACTS Multibeam Communications Package - Technology for the 1990S

    NASA Technical Reports Server (NTRS)

    Graebner, John C.; Cashman, William F.

    1990-01-01

    To maintain its competitive position in the 1990s, satellite communications must evolve to provide new services and to reduce the costs of supplying existing services. NASA's Advanced Communications Technology Satellite (ACTS) program is directed toward developing the technology base that will support this evolution. The ACTS communications payload is optimized for digital communications using a time-division multiple access format. Scanning spot-beam antennas provide high-performance on-demand service to the earth communication stations. On-board processing and switching allow full connectivity in a single-hop network architecture. ACTS employs Ka-band (30/20 GHz) links for communications traffic and includes techniques for mitigating rain fades. Scheduled to be launched by a Space Shuttle in 1992, ACTS will provide in-orbit technology verification and support experimental communications networks for up to four years.

  8. European Telecommunications Conference. Strategic Planning for the 1990s

    NASA Astrophysics Data System (ADS)

    Blackburn, J. F.

    1990-06-01

    The European Telecommunications Conference Strategic Planning for the 1990s provided information to delegates and their companies on strategic planning for the European market, particularly after the advent of the European Single Market at the end of 1992. The conference objective was to examine the impact of the initiatives of the European Commission (EC) and the changing attitudes to service provision by public and private sector organizations on industry and marketing. Organized by Blenheim Online and Logica, 40 delegates attended this conference, mainly from Europe, but with a few from the U.S. The papers were designed to illuminate such questions as emerging market sectors, impact of U.S telecommunications organizations in Europe, mergers and acquisition, standards, and value-added services.

  9. Future proton and electron colliders: Dreams for the 1990's

    SciTech Connect

    Richter, B.

    1988-10-01

    In this paper I have reviewed the possibilities for new colliders that might be available in the 1990's. One or more new proton should be available in the late-90s based on plans of Europe, the US and the USSR. The two very high energy machines, LHC and SSC, are quite expensive, and their construction will be more decided by the politicians' view on the availability of resources than by the physicists' view of the need for new machines. Certainly something will be built, but the question is when. New electron colliders beyond LEP II could be available in the late 1990's as well. Most of the people who have looked at this problem believe that at a minimum three years of RandD are required before a proposal can be made, two years will be required to convince the authorities to go ahead, and five years will be required to build such a machine. Thus the earliest time a new electron collider at high energy could be available is around 1988. A strong international RandD program will be required to meet that schedule. In the field of B factories, PSI's proposal is the first serious step beyond the capabilities of CESR. There are other promising techniques but these need more RandD. The least RandD would be required for the asymmetric storage ring systems, while the most would be required for high luminosity linear colliders. For the next decade, high energy physics will be doing its work at the high energy frontier with Tevatron I and II, UNK, SLC, LEP I and II, and HERA. The opportunities for science presented by experiments at these facilities are very great, and it is to be hoped that the pressure for funding to construct the next generation facilities will not badly affect the operating budgets of the ones we now have or which will soon be turning on. 9 refs., 12 figs., 6 tabs.

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

    PubMed

    Woodgate, G; Sage, C

    1994-01-01

    The inclusion of both ecological and socioeconomic components within landscapes makes possible the perception of the hierarchical character of landscape organization. A research approach is needed to conceptualize cultural landscapes as the product of interaction between society and nature. Richard Norgaard's 1984 paper on coevolutionary agricultural development attempts to meet this challenge. Coevolution is the interactive synthesis of natural and social mechanisms of change that characterize the relationship between social systems and ecosystems. The relationship between population, consumption, and environmental changes is complex. Currently industrialized countries present the biggest threat to global environmental resources. The issue of carrying capacity is the corollary of population and the environment. It is primarily the technological factor rather than population that needs to be controlled. The relationship between rich and poor countries is determined by superior economic power. An analysis of landscape change is made, tracing the coevolution of society and environment from the end of the feudal era and making comparisons with continental Europe. Over the years since 1945 the need to realize potential economies of scale has resulted in a wholesale loss of woodlands, hedgerows, and small ponds in the UK. In a global context the likely impacts of population growth and demographic change on landscapes will be influenced by such socioeconomic factors as technology and affluence; policies that ignore cause and effect; and the traditional tendency to treat the environment as a waste repository and a supply depot. PMID:12290867

  11. Oil and gas markets, companies, and technology in the 1990`s and beyond

    SciTech Connect

    Kennedy, J.L.

    1995-08-01

    During the late 1990`s and beyond, oil prices will be stagnant while costs increase, competition for markets and capital will be fierce, funds available for exploration and development will be limited, and environmental extremists will keep prospective areas off-limits. Higher taxes will limit growth in oil and gas demand and reapportion energy market shares. And a campaign to brand oil use as an ``addiction`` that must be cured will gather steam. But opportunities abound, too, even in the US High-quality properties are available throughout the US, independents can find and develop reserves cheaper than the majors, and new tools are available to reduce risks both in the field and in the market. Gas prices are firming and natural gas is often labeled the ``fuel of the future.`` To succeed in the petroleum industry of the 1990`s, all companies must accept change, be creative, and take initiative. To prosper, oil and gas producers and refiners and those who supply and serve the industry must face the new realities of the market. They cannot mark time until the return of 4,000 active rigs and $40/bbl oil. those days are never coming back. Never.

  12. Welfare and poverty in the Europe of the 1990s: social progress or social dumping?

    PubMed

    Abrahamson, P E

    1991-01-01

    Social policy in Europe is changing fundamentally from a system of public (government) support to a welfare pluralism, or a "welfare mix" supported by the private and public sectors and by voluntary agencies. The overall tendencies are privatization, decentralization, and debureaucratization. With the prospect of a single-market economy within the European Communities in 1993, the fight against poverty in member nations may lead to "social dumping." Two major problems are identified: the lack of guaranteed minimum income schemes in the so-called "Latin Rim" countries, and the effect on workers' and citizens' rights in an integrated Europe. The fight against poverty is--despite some efforts from the Commission of the European Communities--basically left to the individual member states. This portends a gloomy scenario for the poorer populations of Europe in the 1990s. The author examines welfare state types within clusters of countries: the modern (Scandinavia), the corporatist (Federal Republic of Germany), the residual (Britain), and the rudimentary (Latin Rim). The conclusion, unfortunately, is that future overall development of European welfare systems in the 1990s will probably be toward "Americanization," with a move away from the modern, or Scandinavian, model toward a corporatist model for welfare policy. PMID:2071305

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

    ERIC Educational Resources Information Center

    Kent, Mary Mederios

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

  14. Cardiac Exposures in Breast Cancer Radiotherapy: 1950s-1990s

    SciTech Connect

    Taylor, Carolyn W. Nisbet, Andrew; McGale, Paul; Darby, Sarah C.

    2007-12-01

    Purpose: To estimate the doses to the heart and coronary arteries from common breast cancer radiotherapy (RT) regimens used worldwide from the 1950s to the 1990s. Methods and Materials: Virtual simulation and computed tomography planning were used to reconstruct the megavoltage and electron regimens. Manual planning was used for the orthovoltage and brachytherapy regimens. Several sources of variability associated with the dose estimates were assessed. Results: Breast or chest wall RT resulted in whole heart doses of 0.9-14 Gy for left-sided and of 0.4-6 Gy for right-sided irradiation. Internal mammary chain RT delivered heart doses of 3-17 Gy and 2-10 Gy for left- and right-sided irradiation, respectively. For most regimens, the dose to the left anterior descending coronary artery was greater than the heart dose. Scar boost, supraclavicular fossa, and axillary RT delivered mean cardiac doses of {<=}3 Gy. The greatest source of variability in estimating dose from a given regimen was patient anatomy. Conclusion: For most techniques, the greatest radiation doses were received by the anterior part of the heart and the left anterior descending coronary artery, a common site of atherosclerosis causing myocardial infarction. Irradiation of these structures might have contributed to the excess risk of death from heart disease seen after some past breast cancer RT regimens.

  15. Computerized structural mechanics for 1990's: Advanced aircraft needs

    NASA Technical Reports Server (NTRS)

    Viswanathan, A. V.; Backman, B. F.

    1989-01-01

    The needs for computerized structural mechanics (CSM) as seen from the standpoint of the aircraft industry are discussed. These needs are projected into the 1990's with special focus on the new advanced materials. Preliminary design/analysis, research, and detail design/analysis are identified as major areas. The role of local/global analyses in these different areas is discussed. The lessons learned in the past are used as a basis for the design of a CSM framework that could modify and consolidate existing technology and include future developments in a rational and useful way. A philosophy is stated, and a set of analyses needs driven by the emerging advanced composites is enumerated. The roles of NASA, the universities, and the industry are identified. Finally, a set of rational research targets is recommended based on both the new types of computers and the increased complexity the industry faces. Computerized structural mechanics should be more than new methods in structural mechanics and numerical analyses. It should be a set of engineering applications software products that combines innovations in structural mechanics, numerical analysis, data processing, search and display features, and recent hardware advances and is organized in a framework that directly supports the design process.

  16. Fitness and density-dependent population growth in Drosophila melanogaster

    SciTech Connect

    Mueller, L.D.; Ayala, F.J.

    1981-03-01

    The density-dependent rates of population growth were determined for 26 populations of Drosophila melanogaster maintained in the serial transfer system. Twenty-five populations were homozygous for an entire chromosome 2 sampled from nature; the other was a random heterozygous population. Rates of population growth around the carrying capacity cannot explain the large fitness depression of these lines. However, the homozygous lines show large differences in rates of population growth at low densities relative to the random heterozygous standard. The average relative fitness of the homozygous lines, as determined from the growth rates at the lowest density, is 0.51.

  17. The "Cuban Epidemic Neuropathy" of the 1990s: A glimpse from inside a totalitarian disease.

    PubMed

    Coutin-Churchman, Pedro

    2014-01-01

    During the 1990s, Cuba was struck by a rare epidemic disease. Up to 50,000 people were affected by a pathology compromising primarily the optic nerve but also peripheral nerves and even spinal cord. This is a testimony from a direct witness and participant in the initial study of the epidemics showing that in spite of claims of a "multifactorial" etiology, still in the literature, the root cause of this disease is just result of the deliberate deprivation of the most elementary economic rights by extreme Government control over a population left unable to tend to its elementary survival by itself, in spite of a thorough Government-sponsored, universally celebrated Universal Healthcare System. PMID:25024884

  18. Population growth rate and its determinants: an overview.

    PubMed Central

    Sibly, Richard M; Hone, Jim

    2002-01-01

    We argue that population growth rate is the key unifying variable linking the various facets of population ecology. The importance of population growth rate lies partly in its central role in forecasting future population trends; indeed if the form of density dependence were constant and known, then the future population dynamics could to some degree be predicted. We argue that population growth rate is also central to our understanding of environmental stress: environmental stressors should be defined as factors which when first applied to a population reduce population growth rate. The joint action of such stressors determines an organism's ecological niche, which should be defined as the set of environmental conditions where population growth rate is greater than zero (where population growth rate = r = log(e)(N(t+1)/N(t))). While environmental stressors have negative effects on population growth rate, the same is true of population density, the case of negative linear effects corresponding to the well-known logistic equation. Following Sinclair, we recognize population regulation as occurring when population growth rate is negatively density dependent. Surprisingly, given its fundamental importance in population ecology, only 25 studies were discovered in the literature in which population growth rate has been plotted against population density. In 12 of these the effects of density were linear; in all but two of the remainder the relationship was concave viewed from above. Alternative approaches to establishing the determinants of population growth rate are reviewed, paying special attention to the demographic and mechanistic approaches. The effects of population density on population growth rate may act through their effects on food availability and associated effects on somatic growth, fecundity and survival, according to a 'numerical response', the evidence for which is briefly reviewed. Alternatively, there may be effects on population growth rate of

  19. Population Growth in High-Amenity Rural Areas: Does it Bring Socioeconomic Benefits for Long-Term Residents?

    PubMed Central

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

    2011-01-01

    Objective A widely noted concern with amenity-driven rural population growth is its potential to yield only low-wage service-sector employment for long-term residents, while raising local costs of living. This research examines change in socioeconomic status during the 1990s for long-term residents of high-amenity, high-growth rural counties in the United States. Methods Using longitudinal data from the Panel Study of Income Dynamics, in combination with county-level information, we estimate growth-curve models to examine the extent to which the socioeconomic status of long-term residents is associated with amenity-related in-migration. Results We find that, on average, residents in high-growth, amenity-rich rural areas have higher income growth over time and higher levels of initial occupational prestige compared to those from other rural areas, but that socioeconomic gains are primarily for individuals with low baseline prestige. Conclusions The socioeconomic gains made by long-term residents of high-growth, amenity-rich rural areas associated with net in-migration may be limited to individuals with low initial prestige and growth may be due to low-skill service-sector jobs. PMID:21892234

  20. Population Growth and Poverty in the Developing World.

    ERIC Educational Resources Information Center

    Birdsall, Nancy

    1980-01-01

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

  1. Colonization, population growth, and nesting success of Black Oystercatchers following a seismic uplift

    USGS Publications Warehouse

    Gill, V.A.; Hatch, Shyla A.; Lanctot, Richard B.

    2004-01-01

    We present data on the colonization of Middleton Island, Alaska, by Black Oystercatchers (Haematopus bachmani) following the creation of an extensive rocky intertidal zone after the Alaskan earthquake of 1964. The first pair of oystercatchers was detected in 1976, and it was another 5 years before the population increased to three pairs. Oystercatcher numbers increased steadily thereafter, with a population explosion occurring in the 1990s. By 2002, there were 171 territorial pairs on the island. The total number of birds increased from two in 1976 to 718 in 2002. Breeding-pair densities on Middleton Island are the highest recorded for any portion of Alaska, averaging more than 5 pairs per km of shoreline in 2002. Nesting success in 2001 and 2002 was greater (83% or more of the eggs laid hatched) than that reported for any other population of oystercatchers in Alaska or along the Pacific Coast. We attribute this exponential growth rate and exceptionally high reproductive success to the large area of available and suitable habitat, the low number of avian predators and the complete lack of mammalian predators, low rate of nest loss to high tides and storm surges, and a low level of human disturbance. We propose nominating Middleton Island as a regional Western Hemisphere Shorebird Reserve Network site because a high percentage of the world's and region's population of Black Oystercatchers resides there during the breeding season. Further, since Middleton Island may be the single most important site in Alaska for Black Oystercatchers, we suggest it be protected from future development.

  2. Population Growth and a Sustainable Environment.

    ERIC Educational Resources Information Center

    Mortimore, Michael; Tiffen, Mary

    1994-01-01

    Provides a history of farming practices in a densely populated area of Kenya where a recent study of the resource management practices showed positive, not negative, influences of increasing population density on both environmental conservation and productivity. (LZ)

  3. Years of Challenge: The Impact of Demographic and Work Force Trends on Higher Education in the 1990s. A NACUBO Monograph.

    ERIC Educational Resources Information Center

    Hughes, K. Scott; And Others

    This report describes national demographic and work force trends that have important implications for institutions and presents recommended management strategies for the 1990s. Among the trends predicted for the next 10 years are the following: (1) a continuing reduction in the traditional 18-24 year-old college-going population; (2) the…

  4. Volatility and Growth in Populations of Rural Associations

    ERIC Educational Resources Information Center

    Wollebaek, Dag

    2010-01-01

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

  5. Population growth and atmospheric emissions in California. Final report

    SciTech Connect

    Cramer, J.C.

    1998-03-01

    The objectives of this research are to better understand and estimate the net effects of population growth on emissions in California and to estimate the net benefits of air quality programs, which have offset the negative effects of population growth and achieved actual reductions in emissions.

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

    PubMed

    Nakibullah, A

    1998-04-01

    In a poor, overly populated country such as Bangladesh, some believe that a high rate of population growth is a cause of poverty which impedes economic development. Population growth would therefore be exogenous to economic development. However, others believe that rapid population growth is a consequence rather than a cause of poverty. Population growth is therefore endogenous to economic development. Findings are presented from an investigation of whether population growth has been exogenous or endogenous with respect to Bangladesh's development process during the past 3 decades. The increase in per capita real gross domestic product (GDP) is used as a measure of development. Data on population, real GDP per capita, and real investment share of GDP are drawn from the Penn World Table prepared by Summers and Heston in 1991. The data are annual and cover the period 1959-90. Analysis of the data indicate that population growth is endogenous to Bangladesh's development process. These findings are reflected both in the Granger causality tests and the decompositions of variances of detrended real GDP per capita and population growth. PMID:12294506

  7. Pattern of variation in avian population growth rates.

    PubMed Central

    Saether, Bernt-Erik; Engen, Steinar

    2002-01-01

    A central question in population ecology is to understand why population growth rates differ over time. Here, we describe how the long-term growth of populations is not only influenced by parameters affecting the expected dynamics, for example form of density dependence and specific population growth rate, but is also affected by environmental and demographic stochasticity. Using long-term studies of fluctuations of bird populations, we show an interaction between the stochastic and the deterministic components of the population dynamics: high specific growth rates at small densities r(1) are typically positively correlated with the environmental variance sigma(e)(2). Furthermore, theta, a single parameter describing the form of the density regulation in the theta-logistic density-regulation model, is negatively correlated with r(1). These patterns are in turn correlated with interspecific differences in life-history characteristics. Higher specific growth rates, larger stochastic effects on the population dynamics and stronger density regulation at small densities are found in species with large clutch sizes or high adult mortality rates than in long-lived species. Unfortunately, large uncertainties in parameter estimates, as well as strong stochastic effects on the population dynamics, will often make even short-term population projections unreliable. We illustrate that the concept of population prediction interval can be useful in evaluating the consequences of these uncertainties in the population projections for the choice of management actions. PMID:12396511

  8. Forces Shaping the Electronic Publishing Industry of the 1990s.

    ERIC Educational Resources Information Center

    Hawkins, Donald T.; And Others

    1992-01-01

    Reviews the conventional publishing industry, and discusses a study of the electronic publishing industry and its products and processes. Discusses seven major forces affecting it--technology, economics, demographics, social trends, government policies, applications growth, and industry trends--and outlines principles to follow for success in…

  9. Redistricting in the 1990s: A Guide for Minority Groups.

    ERIC Educational Resources Information Center

    O'Hare, William P., Ed.

    This guide provides basic information for members of minority groups who wish to participate effectively in the reapportionment that will take place as a result of the 1990 Census. The guide focuses on Blacks and Hispanics--the largest minority groups and the only ones for which there are reliable population figures that are more recent than the…

  10. Older Adults: Community College Students of the 1990s.

    ERIC Educational Resources Information Center

    Craig, Ford M.

    With a declining pool of youth to draw from, community colleges need to be concerned about what can be done to serve the needs of a burgeoning older adult population. Recent research on the educational needs of older adults reveals that they are interested in: (1) information on such personal business and financial topics as social security…

  11. Bounded Population Growth: A Curve Fitting Lesson.

    ERIC Educational Resources Information Center

    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)

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

    PubMed

    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. PMID:12264235

  13. Interesting times on Krakatau: stand dynamics in the 1990s.

    PubMed Central

    Whittaker, R J; Partomihardjo, T; Jones, S H

    1999-01-01

    The Krakatau Islands, Indonesia, have provided an opportunity for ecologists to track primary succession from the 'clean slate' of 1883, through forest closure in the 1920s, to the contemporary period, in which successional changes take the form of alterations in composition and stature of forest stands rather than gross changes in ecosystem type. This paper reports on permanent forest plots established on the islands in 1989, and fully surveyed again in both 1992 and 1997. Since 1989, the plots have been subject to natural disturbance phenomena in the form of varying combinations of, for example, deposition of volcanic ejecta, landslides, lightning strikes, storm damage and drought. These effects have been concentrated between 1992 and 1997, during which the volcano Anak Krakatau has deposited ash on the islands of Sertung and Panjang, but not on Rakata. Data on stand responses are presented for growth rates (dbh (diameter at breast height, 1.3 m) increment), stem recruitment and mortality, biomass changes partitioned into mortality, ingrowth and growth of established trees), and compositional shifts. The discussion focuses on evaluation of questions and successional models framed earlier in the programme. One general finding is that the stand dominants as of 1989 have tended to decline in number within the plots, generally through low levels of recruitment failing to balance rates of mortality. The effects of disturbance to the plots appear to be evident in terms of mortality and recruitment, dbh increment, and changes in biomass. The patterns of change in the eight plots are quite varied, such that relatively few generalizations are possible. The difficulties of establishing meaningful baseline rates for tree growth and stand biomass are discussed. PMID:11605628

  14. Ultraviolet, visible, and gravity astrophysics: A plan for the 1990's

    NASA Technical Reports Server (NTRS)

    1990-01-01

    NASA's Office of Space Science and Applications (OSSA) receives advice on scientific strategy and priorities from the U.S. National Academy of Sciences. Guidance to the OSSA Astrophysics Division, in particular, is provided by dedicated academy committees, ad hoc study groups, and, at ten-year intervals, by broadly mandated astronomy and astrophysics survey committees charged with making recommendations for the coming decade. Many of the academy's recommendations have important implications for the conduct of ultraviolet and visible-light astronomy from space. Moreover, these areas are now poised for an era of rapid growth. Through technological progress, ultraviolet astronomy has already risen from a novel observational technique four decades ago to the mainstream of astronomical research today. Recent developments in space technology and instrumentation have the potential to generate comparably dramatic strides in observational astronomy within the next ten years. In 1989, the Ultraviolet and Visible Astrophysics Branch of the OSSA Astrophysics Division recognized the need for a new, long-range plan that would implement the academy's recommendations in a way that yielded the most advantageous use of new technology. NASA's Ultraviolet, Visible, and Gravity Astrophysics Management Operations Working Group was asked to develop such a plan for the 1990's. Since the branch holds programmatic responsibility for space research in gravitational physics and relativity, as well as for ultraviolet and visible-light astrophysics, missions in those areas were also included. The working group met throughout 1989 and 1990 to survey current astrophysical problems, assess the potential of new technologies, examine prior academy recommendations, and develop the implementation plan. The present report is the product of those deliberations. Key astrophysical questions to be addressed cover topics such as the structure and evolution of the early universe, energetics of active

  15. Food Production, Population Growth, and Environmental Quality. Caltech Population Program Occasional Papers, Series 1, Number 7.

    ERIC Educational Resources Information Center

    Groth, Edward, III

    This paper, one in a series of occasional publications, discusses trends in food production and population growth, emphasizing how environmental quality will be affected. The series is intended to increase understanding of the interrelationships between population growth and socioeconomic and cultural patterns throughout the world, and to…

  16. Forces of change in the health care system. Implications for cancer care in the 1990s.

    PubMed

    Ettinger, W H

    1991-03-15

    Dramatic changes will occur in the health care system during the 1990s which will profoundly affect the delivery of care for cancer. Perhaps the most important factor is the aging of the population. As the proportion of people who achieve old age increases, the absolute prevalence and incidence of cancer will increase despite improved treatment techniques. This phenomenon will increase health care expenditures despite ongoing efforts to control costs. Second, there will be continuing efforts at cost control and increased emphasis on quality assurance and outcomes by third party payers. Providers will be scrutinized and compared with one another. The large payers of the nation's health care bills will demand proof of outcome and cost leading to bidding by providers and payment only to those who have the best outcome for the least money. Third, there will be an increasing emphasis on prevention and screening, in public health policy, an approach that may conflict with personal freedom. Fourth, there will be increasing deliberations and questions about the ethics of the health care system and treatment decisions. There will be continuing debate about the need for a rationing of health care and the right of individual privacy versus the states' right to preserve life. These changes will impact on all health care professionals whose practice includes patients with cancer. PMID:2001566

  17. Gay and bisexual men's use of the Internet: research from the 1990s through 2013.

    PubMed

    Grov, Christian; Breslow, Aaron S; Newcomb, Michael E; Rosenberger, Joshua G; Bauermeister, Jose A

    2014-01-01

    We document the historical and cultural shifts in how gay and bisexual men have used the Internet for sexuality between the 1990s and 2013-including shifting technology as well as research methods to study gay and bisexual men online. Gay and bisexual men have rapidly taken to using the Internet for sexual purposes: for health information seeking, finding sex partners, dating, cybersex, and pornography. Men have adapted to the ever-evolving technological advances that have been made in connecting users to the Internet-from logging on via dial-up modem on a desktop computer to geo-social-sexual networking via handheld devices. In kind, researchers have adapted to the Internet to study gay and bisexual men. Studies have carefully considered the ethics, feasibility, and acceptability of using the Internet to conduct research and interventions. Much of this work has been grounded in models of disease prevention, largely as a result of the ongoing HIV/AIDS epidemic. The need to reduce HIV in this population has been a driving force to develop innovative research and Internet-based intervention methodologies. The Internet, and specifically mobile technology, is an environment gay and bisexual men are using for sexual purposes. These innovative technologies represent powerful resources for researchers to study and provide outreach. PMID:24754360

  18. Preparing public health leaders for the 1990s.

    PubMed Central

    Roemer, M I

    1988-01-01

    Public health leadership is urgently needed throughout the world. In most local, provincial, and national jurisdictions, such responsibility has been assumed by doctors of clinical medicine, who know much about treatment of disease in individual patients but very little about prevention of disease and promotion of health in populations or the management of health systems. Effective leadership in public health requires a new profession, with generalized education in the basic tools of social analysis, health and disease in populations, promotion of health and prevention of disease, and health care systems and their management. More than 40 distinct scientific subjects have been developed in these fields over the years, and current faculties are qualified to teach them. To provide this education would require about 5 years of academic and field studies, after a bachelor's degree. Schools of public health now train doctoral-level specialists who are prepared in the PhD tradition for academic posts. These schools should also develop educational programs for doctoral-level generalists who are qualified to provide community health leadership at local, provincial, and national levels. PMID:3140268

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

    PubMed

    Loriaux, M

    1991-12-01

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

  20. Global child health: challenges and goals in the 1990s.

    PubMed

    Reid, R S

    1994-01-01

    The UNICEF message to the pediatricians and child health experts attending the Regional Pediatric Congress of the Union of National Pediatric Societies of Turkish Republics is that the way children are conceptualized in the development process has a major impact on poverty. UNICEF argues that human resource development is the safest way out of population pressure, vanishing forests, and despoiled rivers. Thailand, South Korea, Taiwan, and Singapore are examples of countries that "sacrificed, deferred consumer gratification of the elites, and disciplined themselves" in order to provide better care for their children in terms of good nutrition, good health care, and rigorous primary and secondary education for all children. Family planning was available to all parents. The emphasis was on hygiene, immunization, clean water supplies, and sanitation. Lower infant and child mortality created confidence in child survival and parental willingness to have fewer children. The working population is healthier due to the state nutrition programs and a better skilled labor force due to education and training. These countries are no longer underdeveloped because of the priority on children for over a generation and a half. Robert Heilbroner has described this strategy for development as based on social development, human development, and protection of children aged under 5 years. The Alma Ata conference in 1976 was instrumental in focusing on the health of the child by setting a standard of health for all by the year 2000. Many countries are moving in the direction proposed in these agendas. The result has been a 33% reduction in child mortality within 10 years and greater immunization in some developing countries than in Europe and North America. Immunization rates in Ankara, Turkey; Calcutta, India; Lagos, Nigeria; and Mexico City are higher than in Washington, D.C. or New York City. The 1990 World Summit for Children found that the following rules are applicable to

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

    PubMed Central

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

    2016-01-01

    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. PMID:26699457

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

    PubMed

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

    2016-01-26

    The human population has grown significantly since the onset of the Holocene about 12,000 y ago. Despite decades of research, the factors determining prehistoric population growth remain uncertain. Here, we examine measurements of the rate of growth of the prehistoric human population based on statistical analysis of the radiocarbon record. We find that, during most of the Holocene, human populations worldwide grew at a long-term annual rate of 0.04%. Statistical analysis of the radiocarbon record shows that transitioning farming societies experienced the same rate of growth as contemporaneous foraging societies. The same rate of growth measured for populations dwelling in a range of environments and practicing a variety of subsistence strategies suggests that the global climate and/or endogenous biological factors, not adaptability to local environment or subsistence practices, regulated the long-term growth of the human population during most of the Holocene. Our results demonstrate that statistical analyses of large ensembles of radiocarbon dates are robust and valuable for quantitatively investigating the demography of prehistoric human populations worldwide. PMID:26699457

  3. Parameter Estimates in Differential Equation Models for Population Growth

    ERIC Educational Resources Information Center

    Winkel, Brian J.

    2011-01-01

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

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

    ERIC Educational Resources Information Center

    King, Timothy; Kelley, Allen C.

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

  5. A Role for M-Matrices in Modelling Population Growth

    ERIC Educational Resources Information Center

    James, Glyn; Rumchev, Ventsi

    2006-01-01

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

  6. Population growth. Its magnitude and implications for development.

    PubMed

    Birdsall, N

    1984-09-01

    A summary of the 1984 World Development Report is provided. The 3 major points stressed in the report were: 1) rapid population growth adversely affects development, 2) governments must adopt policies to reduce fertility, and 3) policies adopted by many countries have effectively reduced fertility. World population growth began accelerating at 0.5%/year in the 18th century, and by 1950 the annual acceleration rate was 2%. Most of the increase in population size is occurring in less developed countries, and this increase is due in part to the recent decline in mortality experienced by these countries. Of the 80 million individuals who will be added to the world's population in 1984, 70 million will be in the developing countries. Since 1965 the population growth rate for developing countries as a group declined from 2.4% to 2%. However, because of the high proportion of younger aged individuals in developing countries, the decline in fertility is expected to level off. According to World Bank population projections, the world population will stabilize at around 11 billion in 2150. During the interium, the population of developing countries will increase from its present level of 3.6 billion to 8.4 billion, and the population of developed countries will increase from 1.2 billion to 1.4 billion. These projections are probably overly optimistic. The adverse impact on development of rapid population growth is due to several factors. 1st, resources which could be used for investment must instead be used to fulfill the consumption needs of an increased number of people. 2nd, increases in the labor force must be absorbed by the agricultural sector, and this reduces agricultural productivity. 3rd, rapid population growth increases management problems. The adaption of policies by governments to reduce fertility is a necessary step in halting population growth. For poor families, children provide economic security. Therefore, governments must act to improve the economic

  7. Educational Inequalities among Latin American Adolescents: Continuities and Changes over the 1980s, 1990s and 2000s

    PubMed Central

    Marteleto, Letícia; Gelber, Denisse; Hubert, Celia; Salinas, Viviana

    2012-01-01

    The goal of this paper is to examine recent trends in educational stratification for Latin American adolescents growing up in three distinct periods: the 1980s, during severe recession; the 1990s, a period of structural adjustments imposed by international organizations; and the late 2000s, when most countries in the region experienced positive and stable growth. In addition to school enrollment and educational transitions, we examine the quality of education through enrollment in private schools, an important aspect of inequality in education that most studies have neglected. We use nationally representative household survey data for the 1980s, 1990s and 2000s in Brazil, Chile, Mexico and Uruguay. Our overall findings confirm the importance of macroeconomic conditions for inequalities in educational opportunity, suggesting important benefits brought up by the favorable conditions of the 2000s. However, our findings also call attention to increasing disadvantages associated with the quality of the education adolescents receive, suggesting the significance of the EMI framework—Effectively Maintained Inequality—and highlighting the value of examining the quality in addition to the quantity of education in order to fully understand educational stratification in the Latin American context. PMID:22962512

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

    NASA Astrophysics Data System (ADS)

    Cremer, Jonas; Melbinger, Anna; Frey, Erwin

    2012-02-01

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

  9. Staying single in the 1990s: single-handed practitioners in the new National Health Service.

    PubMed

    Lunt, N; Atkin, K; Hirst, M

    1997-08-01

    The U.K. health care system is organised around independent medical practitioners who work in community settings and act as gatekeepers for acute health interventions. Recent developments in U.K. health policy have revolutionised the environment within which all general medical practitioners (GPs) operate. The last five years in the U.K. have seen the most fundamental health service reforms since the inception of the National Health Service (NHS) in 1946: namely, the development of the internal market, an increasing emphasis on primary health care, and changes to the GP Contract in 1990. Single-handed GPs (practitioners not in partnership with other GPs) traditionally work in the most deprived areas with the greatest health and social problems. The current restructuring and the subsequent organisational and policy initiatives present particular problems for single-handed practitioners. How single-handed practitioners respond to the reforms raises particularly important debates that are significant both for themselves and for the populations they serve. Drawing upon a range of sources, this paper discusses three central issues that emerge. First, how do single-handed practices relate to the more managerial role envisaged for authorities responsible for supporting primary health care? Second, given the development of the internal market, how do single-handed practices fare in influencing local policy and priority setting? Third, to what extent can single-handed practitioners take advantage of the opportunities to hold their own budgets? Overall, in the context of recent U.K. health care reforms, what is the future for "staying single in the 1990s"? PMID:9232729

  10. Gay and Bisexual men's use of the Internet: Research from the 1990s through 2013

    PubMed Central

    Grov, Christian; Breslow, Aaron S.; Newcomb, Michael E.; Rosenberger, Joshua G.; Bauermeister, Jose A

    2014-01-01

    In this review, we document the historical and cultural shifts in how gay and bisexual men have used the Internet for sexuality between the 1990s and 2013. Over that time, gay and bisexual men have rapidly taken to using the Internet for sexual purposes: sexual health information seeking, finding sex partners, dating, cybersex, and pornography. Gay and bisexual men have adapted to the ever-evolving technological advances that have been made in connecting users to the Internet—from logging into the World Wide Web via dial-up modem on a desktop computer to geo-social and sexual networking via a handheld device. In kind, researchers too have adapted to the Internet to study gay and bisexual men, though not at the same rapid pace at which technology (and its users) have advanced. Studies have carefully considered the ethics, feasibility, and acceptability of using the Internet to conduct research and interventions with gay and bisexual men. Much of this work has been grounded in models of disease prevention, largely as a result of the ongoing HIV/AIDS epidemic. The urgent need to reduce HIV in this population has been a driving force to develop innovative research and Internet-based intervention methodologies. Moving forward, a more holistic understanding of gay and bisexual men's sexual behavior might be warranted to address continued HIV and STI disparities. The Internet, and specifically mobile technology, is an environment gay and bisexual men are using for sexual purposes. These innovative technologies represent powerful resources for researchers to study and provide rapidly evolving outreach to gay and bisexual men. PMID:24754360

  11. Gender equity in health care in Sweden--minor improvements since the 1990s.

    PubMed

    Jonsson, Pia Maria; Schmidt, Ingrid; Sparring, Vibeke; Tomson, Göran

    2006-06-01

    A report by the Swedish National Committee on Gender Disparities in Patient Care (1996) identified many shortcomings in the ability of the health sector to gear patient management and treatment to the specific needs of men and women. To promote gender equity in health care, the Committee presented several proposals relating to research, education, monitoring, and evaluation of health services and the responsibilities of health authorities. In 2002, the Swedish Government authorised the National Board of Health and Welfare to review and analyse gender equity trends in health care. Data from, e.g. the national quality registers, epidemiological health data registers, population surveys, and Patient Trust Boards were compiled to identify gender disparities in the quality and accessibility of health services. The curricula of medical universities and the policies of major research funds were reviewed, as were developments in major fields of health research. The National Board found that many of the gender disparities identified in the 1990s still exist, e.g. access to advanced evidence-based technologies such as coronary interventions. As previously, women account for around 60%, and men for 40%, of complaints, e.g. to the Patients' Advisory Committees. Many of the proposals of the National Committee have not been fully implemented by the national authorities or the county councils. We conclude that promoting gender equity in health care is an important but difficult task for health authorities. To make health services more gender sensitive a combination of strategies, including enforcement by guidelines and regulations, may be needed. PMID:16154225

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

    USGS Publications Warehouse

    Flint, P.L.; Grand, J.B.; Rockwell, R.F.

    1998-01-01

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

  13. Understanding the size growth of massive galaxies through stellar populations

    NASA Astrophysics Data System (ADS)

    Ferreras, Ignacio

    2015-08-01

    The growth of massive galaxies remains an open problem. The observational evidence seems to converge on a two-stage scenario, where a compact massive core is formed during an early, intense burst, followed by a more extended process of mass and size growth at intermediate redshift (z<2). This talk focuses on the latter, exploring the growth of massive galaxies through a detailed analysis of the stellar populations in close pairs, to study their formation history. Two surveys are explored (SHARDS and GAMA), probing the stellar populations of pre-merging systems out to z~1.3, and down to a mass ratio ~1:100. We will compare the results between medium band spectral fitting (SHARDS) and those from a more targeted analysis of line strengths in the GAMA data. The combination of the two datasets provide a unique insight of the growth channel of massive galaxies via mergers.

  14. Latino Population Growth and Hospital Uncompensated Care in California

    PubMed Central

    O’Brien, Matthew J.; Mennis, Jeremy; Alos, Victor A.; Grande, David T.; Roby, Dylan H.; Ortega, Alexander N.

    2015-01-01

    Objectives. We examined the association between the size and growth of Latino populations and hospitals’ uncompensated care in California. Methods. Our sample consisted of general acute care hospitals in California operating during 2000 and 2010 (n = 251). We merged California hospital data with US Census data for each hospital service area. We used spatial analysis, multivariate regression, and fixed-effect models. Results. We found a significant association between the growth of California’s Latino population and hospitals’ uncompensated care in the unadjusted regression. This association was still significant after we controlled for hospital and community population characteristics. After we added market characteristics into the final model, this relationship became nonsignificant. Conclusions. Our findings suggest that systematic support is needed in areas with rapid Latino population growth to control hospitals’ uncompensated care, especially if Latinos are excluded from or do not respond to the insurance options made available through the Affordable Care Act. Improving availability of resources for hospitals and providers in areas with high Latino population growth could help alleviate financial pressures. PMID:26066960

  15. Populational Growth Models Proportional to Beta Densities with Allee Effect

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  16. Glass Ceiling in Academic Administration in Turkey: 1990s versus 2000s

    ERIC Educational Resources Information Center

    Gunluk-Senesen, Gulay

    2009-01-01

    This paper assesses the glass ceiling for academics in the Turkish universities with reference to top administration positions: rectors and deans. Glass ceiling indicators show that the glass ceiling thickened from the 1990s to late 2000s. The findings are discussed against the background of the transformation in the Turkish universities in the…

  17. Parents and Schooling in the 1990s. Parent Involvement at the Middle School Level.

    ERIC Educational Resources Information Center

    ERIC Review, 1991

    1991-01-01

    The "ERIC Review" announces research results, publications, and new programs relevant to each issue's theme topic. This theme issue is devoted to the topic of "Parent Involvement in Education" and contains three principal articles: "Parents and Schooling in the 1990s," by Erwin Flaxman and Morton Inger; "Parent Involvement at the Middle School…

  18. Equality, Diversity and Opportunity: Civil Rights and Affirmative Action in the 1990s.

    ERIC Educational Resources Information Center

    Winston, Judith A.

    1991-01-01

    Challenges to civil rights and affirmative action in the 1990s are identified. Five cases of racial, sex, ethnic, and reverse discrimination behind the Civil Rights bills of 1990 and 1991 are discussed. The ultimate challenge is to demonstrate that if civil rights litigants win, others need not lose. (SLD)

  19. Merger of Higher Education Institutions: Case Studies in China in the 1990s

    ERIC Educational Resources Information Center

    Su, Mingni

    2009-01-01

    This study explores two specific cases of institutional mergers in the field of higher education. The two cases took place in China in the 1990s. One of the cases might be labeled a vertical merger and the other a horizontal merger. The former simply implies a merger between higher education institutions with equal status and the same level of…

  20. Campus Budgeting for Tough Times: Lessons from the First Half of the 1990s. Rockefeller Reports.

    ERIC Educational Resources Information Center

    Burke, Joseph C.

    This report lists 11 budgetary principles for higher education institutions, and presents the results of a survey which examined whether the practices of four-year public higher education institutions in California, Florida, Massachusetts, New York, Texas, and Wisconsin followed these precepts during the fiscal problems of the early 1990s. The 11…

  1. Grade Inflation Marches On: Grade Increases from the 1990s to 2000s

    ERIC Educational Resources Information Center

    Kostal, Jack W.; Kuncel, Nathan R.; Sackett, Paul R.

    2016-01-01

    Grade inflation threatens the integrity of college grades as indicators of academic achievement. In this study, we contribute to the literature on grade inflation by providing the first estimate of the size of grade increases at the student level between the mid-1990s and mid-2000s. By controlling for student characteristics and course-taking…

  2. El Nino During the 1990's: Harbinger of Climatic Change or Normal Fluctuation?

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2000-01-01

    Today, El Nino refers to the extreme warming episodes of the globally effective, coupled ocean-atmospheric interaction commonly known as ENSO (i.e., "El Nino-Southern Oscillation"). Concerning its observed decadal frequency and severity, El Nino during the 1990's has often been regarded as being anomalous. Results of analysis reported herein; however, appear to mitigate this belief.

  3. El Nino During the 1990s: Harbinger of Climatic Change or Normal Fluctuation

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2000-01-01

    Today, El Nino refers to the extreme warming episodes of the globally effective, coupled ocean-atmospheric interaction commonly known as ENSO (i.e., "El Nino-Southern Oscillation"). Concerning its observed decadal frequency and severity, El Nino during the 1990's has often been regarded as being anomalous. Results of analysis reported herein; however, appear to mitigate this belief.

  4. Blueprints for Indian Education: Research and Development Needs for the 1990s. ERIC Digest.

    ERIC Educational Resources Information Center

    Cahape, Patricia

    Two landmark efforts to describe the condition of American Indian and Alaska Native education nationwide and to call for specific solutions took place in the early 1990s. These efforts were the Indian Nations At Risk Task Force and the White House Conference on Indian Education. This digest summarizes Task Force and Conference recommendations…

  5. Migration of Retirement-Age Blacks to Nonmetropolitan Areas in the 1990s

    ERIC Educational Resources Information Center

    Beale, Calvin L.; Fuguitt, Glenn V.

    2011-01-01

    Older blacks migrated to nonmetropolitan (nonmetro) communities in the 1990s to a degree not true of the past. Some of the nonmetro counties that attracted them are well-known retirement areas also favored by other retirees, mostly whites. Two-thirds of black retirement counties, however, are areas in the Old South that are not attracting other…

  6. A Just Transition? Lessons from Defense Worker Adjustment in the 1990s. Technical Paper No. 237.

    ERIC Educational Resources Information Center

    Powers, Laura; Markusen, Ann

    A study examined the experiences of some 1.4 million American defense industry workers, displaced in the wake of the Cold War, as a way of reviewing and evaluating national policies toward worker adjustment and re-employment as they have evolved in the 1990s. The study found that the federal government, through the Department of Labor,…

  7. Information Systems in the University of Saskatchewan Libraries: A Vision for the 1990s.

    ERIC Educational Resources Information Center

    Saskatchewan Univ., Saskatoon. Libraries.

    This report describes the vision of the Information Systems Advisory Committee (ISAC) of an Information Systems Model for the 1990s. It includes an evaluation of the present automation environment at the university, a vision of library automation at the University of Saskatchewan between 1994 and 1999, and specific recommendations on such issues…

  8. Families in Poverty in the 1990s: Trends, Causes, Consequences, and Lessons Learned.

    ERIC Educational Resources Information Center

    Seccombe, Karen

    2000-01-01

    During the 1990s, poverty rates in the United States remained relatively stable despite a robust economy. This paper reviews the research and theoretical and conceptual developments during the past decade, including how the poverty line was developed; the causes of the virtually unchanged poverty rate; and the consequences of poverty for children.…

  9. Feature Articles on African Americans in Sports Illustrated in the 1990s

    ERIC Educational Resources Information Center

    Angela Lumpkin

    2009-01-01

    This descriptive study examined whether the coverage of African Americans in the feature articles in Sports Illustrated during the 1990s was representative of their participation levels. Nearly half of the articles featured European Americans; about one-third featured African Americans. More African Americans were featured in basketball, boxing,…

  10. El Nino during the 1990s: Harbinger of Climatic Change or Normal Fluctuation?

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1999-01-01

    Today, El Nino refers to the extreme warming episodes of the globally effective, coupled ocean-atmospheric interaction commonly known as ENSO (i.e., "El Nino-Southern Oscillation"). Concerning its observed decadal frequency and severity, El Nino during the 1990s has often been regarded as being anomalous. Results of analysis reported herein, however, appear to mitigate this belief. For example, regarding the frequency and severity of El Nino, the decade of the 1990s is found to compare quite favorably with that of preceding decades. Hence, the 1990s probably should not be regarded as being anomalous. On the other hand, the number of El Nino-related months per decade has sharply increased during the 1990s, as compared to the preceding four decades, hinting of a marginally significant upward trend. Perhaps, this is an indication that the Earth is now experiencing an ongoing global climatic change. Continued vigilance during the new millennium, therefore, is of paramount importance for determining whether or not this "hint" of a global change is real or if it merely reflects a normal fluctuation of climate.

  11. The Role of Communication Satellites in Education and Training: The 1990s.

    ERIC Educational Resources Information Center

    Polcyn, Kenneth A.

    1981-01-01

    Presents an overview of satellite technology and trends in its use, reviews the evolution of education and training applications of communication satellites, and prognosticates about the possible national and international uses during the 1990s. A bibliography of 26 items is included. (CHC)

  12. World Agriculture: Review and Prospects into the 1990s. A Summary.

    ERIC Educational Resources Information Center

    Winrock International Livestock Research & Training Center. Morrilton, AR.

    The four chapters of this analysis of world agriculture deal with production, consumption, and world trade. World food production and consumption continued to grow rapidly in the 1970's, but at a rate somewhat slower than in the 1960's. It is projected that for the 1990's consumption will increase faster than production in most of the world's…

  13. Exiting Welfare in the 1990s: Did Public Policy Influence Recipients' Behavior?

    ERIC Educational Resources Information Center

    Hofferth, Sandra L.; Stanhope, Stephen; Harris, Kathleen Mullan

    2002-01-01

    Evaluates the association between welfare policies implemented by states in the early to mid-1990s and the rate at which female household heads with children exit AFDC for work or for non-work reasons. Reports that waiver policies requiring work for mothers of very young children are associated with more rapid exits through employment. (Contains…

  14. Technology and Reference Changes in the 1990s: An Annotated Bibliography.

    ERIC Educational Resources Information Center

    Dennison, Russell F.

    This paper presents an annotated bibliography of 69 articles published in the 1990s that examine the impact of technology on reference service in public, school, and academic libraries. The paper is organized in the following seven parts, each dealing with a different type of application of technology: (1) "General Change Caused by Technology";…

  15. Issues and Concerns for Local Government: Virginia in the 1990s.

    ERIC Educational Resources Information Center

    Crockett, Mark

    Many challenges face local governments in Virginia and nationwide in the 1990s. As federal funding has decreased, local governments have been forced to take on greater responsibilities. This increased workload has created a greater demand for resources and forced many localities to raise taxes. Citizens have often voiced opposition to these tax…

  16. Focus on the 1990's: International Trade Opportunities for the Permian Basin.

    ERIC Educational Resources Information Center

    Midland Coll., TX. Business and Economic Development Center.

    Designed to highlight business opportunities of the 1990s as well as available educational programs relating to international business, this report contains six presentations from a 1990 conference on international trade hosted by Midland College (MC). The first article, "Texas in the Global Economy: Attitude and Opportunity," by John A. Adams,…

  17. Mexican American Women's Activism at Indiana University in the 1990s

    ERIC Educational Resources Information Center

    Hernandez, Ebelia

    2013-01-01

    This article offers a historical analysis of documents and narratives from Mexican American women that reflect the tumultuous 1990s at Indiana University. Their recollections reveal how they became activists, the racist incidents that compelled them into activism, and the racial tensions and backlash towards identity politics felt by students of…

  18. Information Technology Issues in the 1990s: An Analysis from a CAUSE Postcard Survey for 1994.

    ERIC Educational Resources Information Center

    Temares, M. Lewis; Zastrocky, Michael R.

    During the past 3 years, CAUSE and the University of Miami (Florida) have sponsored a survey to identify the most important issues facing information technology managers for the 1990s. Data from previous years were merged with postcard survey data from the 1994 survey. The survey, which was mailed to 1,012 institutions of higher learning and sent…

  19. Putting Children First: A Progressive Family Policy for the 1990s.

    ERIC Educational Resources Information Center

    Kamarck, Elaine Ciulla; Galston, William A.

    Four policy papers delineate a progressive family policy for the 1990s that makes the family central among social issues and children central in families. An extensive introduction delineates the split between leaders' and ordinary citizens' views on the family and provides a summary of the papers. The first paper offers an economic review of the…

  20. Food for Thought: Children's Diets in the 1990s. Policy Brief.

    ERIC Educational Resources Information Center

    Gleason, Philip; Suitor, Carol

    Since the late 1980s, identifying nutritional problems in children's and adults' diets and developing initiatives to help Americans improve what they eat have received considerable attention. This policy brief summarizes 2 studies of children's nutrition with the objectives of describing the diets of school-age children as of the mid-1990s,…

  1. The Mid-1990s Earned Income Tax Credit Expansion: EITC and Welfare Caseloads

    ERIC Educational Resources Information Center

    Lim, Younghee

    2008-01-01

    Research and policy scholars have suggested that recent welfare caseload reductions have coincided with welfare reform efforts; however, few studies have incorporated the impacts of the Earned Income Tax Credit (EITC) expansions in the 1990s. Using annual state-level administrative data, the author estimated the effects of the fully phased-in…

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

    PubMed

    Lee, Charlotte T; Tuljapurkar, Shripad

    2008-06-01

    We present a demographic model that describes the feedbacks between food supply, human mortality and fertility rates, and labor availability in expanding populations, where arable land area is not limiting. This model provides a quantitative framework to describe how environment, technology, and culture interact to influence the fates of preindustrial agricultural populations. We present equilibrium conditions and derive approximations for the equilibrium population growth rate, food availability, and other food-dependent measures of population well-being. We examine how the approximations respond to environmental changes and to human choices, and find that the impact of environmental quality depends upon whether it manifests through agricultural yield or maximum (food-independent) survival rates. Human choices can complement or offset environmental effects: greater labor investments increase both population growth and well-being, and therefore can counteract lower agricultural yield, while fertility control decreases the growth rate but can increase or decrease well-being. Finally we establish equilibrium stability criteria, and argue that the potential for loss of local stability at low population growth rates could have important consequences for populations that suffer significant environmental or demographic shocks. PMID:18439637

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

    PubMed

    Madulu, N F

    1995-03-01

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

  4. Meteorological limits on the growth and development of screwworm populations

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

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

    PubMed

    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

  6. The “Cuban Epidemic Neuropathy” of the 1990s: A glimpse from inside a totalitarian disease

    PubMed Central

    Coutin-Churchman, Pedro

    2014-01-01

    During the 1990s, Cuba was struck by a rare epidemic disease. Up to 50,000 people were affected by a pathology compromising primarily the optic nerve but also peripheral nerves and even spinal cord. This is a testimony from a direct witness and participant in the initial study of the epidemics showing that in spite of claims of a “multifactorial” etiology, still in the literature, the root cause of this disease is just result of the deliberate deprivation of the most elementary economic rights by extreme Government control over a population left unable to tend to its elementary survival by itself, in spite of a thorough Government-sponsored, universally celebrated Universal Healthcare System. PMID:25024884

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

    ERIC Educational Resources Information Center

    Newland, Kathleen

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

  8. Is There Hidden Potential for Rural Population Growth in Sweden?

    ERIC Educational Resources Information Center

    Niedomysl, Thomas; Amcoff, Jan

    2011-01-01

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

  9. The Economic Base of Recent Population Growth in Nonmetropolitan Settings.

    ERIC Educational Resources Information Center

    Long, Larry; DeAre, Diana

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

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

    ERIC Educational Resources Information Center

    Daley, Michael; Hillier, Douglas

    1981-01-01

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

  11. Growth, survival, longevity, and population size of the Big Mouth Cave salamander (Gyrinophilus palleucus necturoides) from the type locality in Grundy County, Tennessee, USA

    USGS Publications Warehouse

    Niemiller, Matthew L.; Glorioso, Brad M.; Fenolio, Dante B.; Reynolds, R. Graham; Taylor, Steven J.; Miller, Brian T.

    2016-01-01

    Salamander species that live entirely in subterranean habitats have evolved adaptations that allow them to cope with perpetual darkness and limited energy resources. We conducted a 26-month mark–recapture study to better understand the individual growth and demography of a population of the Big Mouth Cave Salamander (Gyrinophilus palleucus necturoides). We employed a growth model to estimate growth rates, age at sexual maturity, and longevity, and an open population model to estimate population size, density, detectability, and survival rates. Furthermore, we examined cover use and evidence of potential predation. Individuals probably reach sexual maturity in 3–5 years and live at least nine years. Survival rates were generally high (>75%) but declined during the study. More than 30% of captured salamanders had regenerating tails or tail damage, which presumably represent predation attempts by conspecifics or crayfishes. Most salamanders (>90%) were found under cover (e.g., rocks, trash, decaying plant material). Based on 11 surveys during the study, population size estimates ranged from 21 to 104 individuals in the ca. 710 m2 study area. Previous surveys indicated that this population experienced a significant decline from the early 1970s through the 1990s, perhaps related to silvicultural and agricultural practices. However, our data suggest that this population has either recovered or stabilized during the past 20 years. Differences in relative abundance between early surveys and our survey could be associated with differences in survey methods or sampling conditions rather than an increase in population size. Regardless, our study demonstrates that this population is larger than previously thought and is in no immediate risk of extirpation, though it does appear to exhibit higher rates of predation than expected for a species believed to be an apex predator of subterranean food webs.

  12. Immigration enhances fast growth of a newly established source population.

    PubMed

    Santoro, Simone; Green, Andy J; Figuerola, Jordi

    2016-04-01

    Abstract. Immigration and local recruitment play a central role in determining the growth rate of breeding populations. Unraveling these processes in newly established pop- ulations is of great importance to increase our understanding of how species change their distributions in response to global change. We studied the largest colony of glossy ibis (Plegadis falcinellus) in Western Europe (established in 1996 in Doñana, SW-Spain) by using capture-recapture methods, count estimates, and projection matrix modeling to: (1) test the effect of resource availability and competition on local recruitment dynamics, (2) investigate the contribution of local recruitment vs. immigration on population growth, and (3) assess the role of this population in source/sink dynamics. We found different dynamics before and after the establishment of satellite colonies in Doñana in 2004. Between 1996 and 2003, the population increased rapidly, fueled by immigrants (≈ 58 breeding females/ yr). Between 2003 and 2007, however, both colony size increase and immigration were negligible. Immigration played a major role in colony growth, but simultaneously this colony was a source population driving expansion of the species range as suggested by (1) absolute and relative estimates of the observed growth rate relative to that predicted by self-recruitment, and (2) numerous observations of Doñana-born individuals breeding elsewhere. Local recruitment, which was particularly high for first-year individuals (probability > 0.8 for the early study years), was not directly related to resource availability or previous-year breeding success. Local recruitment decreased rapidly at a threshold population size, however, when other satellite colonies became established at Dofiana. Our study suggests that even when recruitment at an early age and high productivity are observed, immigration can still play a pivotal role in promoting the fast growth of new populations at the edge of a species range, at

  13. Habitat-Specific Population Growth of a Farmland Bird

    PubMed Central

    Arlt, Debora; Forslund, Pär; Jeppsson, Tobias; Pärt, Tomas

    2008-01-01

    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 λs: −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 λs: −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. PMID:18714351

  14. A population growth model forced by random, episodic disturbances

    NASA Astrophysics Data System (ADS)

    Peckham, S. D.

    2011-12-01

    As a first step to quantify and better understand the nature of thresholds in ecosystems, a prototype population dynamics model has been developed and analyzed for the case where a population is subjected to random, episodic disturbances. This model assumes that disturbances occur at random times (following a Poisson event process) and have random magnitudes that determine the fraction of the population that survives the disturbance. Disturbances may be events such as fire, drought, disease or infestation. Between disturbances, the model assumes that population growth is deterministic and can be modeled by an exponential or logistic equation. The model is characterized by time, t, and four other parameters: the initial population size, N0, the per capita growth rate, r, the expected number of disturbance events per unit time, λ , and μ = E(X), where X is the random fraction (between 0 and 1) of the population that survives a given disturbance. What is nice about this simple, stochastic model is that it is mathematically tractable and clearly exhibits threshold behavior that can be computed explicitly in terms of the model parameters. In particular, the long-term behavior of the model is characterized by an easily-computed indicator that is a function of the model parameters. Whenever the model parameters are such that this indicator is less than zero, the expected value of the random population size declines over time and is unsustainable. But whenever it is greater than zero, the expected population size grows, despite the random disturbances. The case where the indicator is zero therefore represents a type of critical threshold for this problem that determines whether or not the population is likely to survive the disturbances. A number of analytic results will be presented along with numerical results from a large number of simulations.

  15. [Rapid population growth is unfavorable to prosperity of minority areas].

    PubMed

    Zhang, T

    1991-04-01

    According to China's 1990 census, the ethnic minority population increased by 35.5% from the 1982 census, 23 percentage points higher than the Han nationality. Among 55 ethnic minorities, 16 had growth rates of over 50% between 1982 and 1990. The Korean ethnic minority had the lowest growth rate, which was only 8.73%. The high growth rate of the ethnic minority population was due to the high level of natural increase and policy factors. With the changing policies toward ethnic minorities, preferential treatment has been give to the them in education, employment, career promotion, and childbearing quota. These policies stimulated switching from the Han nationality to the minority status. 50-60% of growth in the minority population between the 2 censuses has been attributed to the status switching. The per capita GNP in the minority administrative areas was 54.9% lower than in Han areas in 1980. It became 69% lower in 1988. Excessive growth of the ethnic minority population hindered education attainment and economic and resources development. Some ethnic minorities have an illiteracy rate of over 90% and an infant mortality rate of 171/1000. The ecological environment in certain minority areas is deteriorating due to extensive tree-felling and primitive farming methods. In contrast, the Korean minority developed its education program earlier on. Its total fertility rate has been around 1.4 since 1974 and it is gradually changing into a stationary population. Currently, no Korean National counties or townships are below the poverty line. The prevalence of disability is 3.5% in the Korean population, the lowest of all the ethnic groups. It is important to focus population programs among the ethnic minorities to increase their health and educational status. Promoting family planning programs, strictly enforcing the criteria for switching to minority status or setting deadlines to preference treatment eligibility for those who switched status could be possible policies

  16. Understanding the size growth of massive galaxies through stellar populations

    NASA Astrophysics Data System (ADS)

    Ferreras, I.; Trujillo, I.; Mármol-Queraltó, E.; Pérez-González, P.

    Massive early-type galaxies undergo a significant process of evolution with redshift on the stellar mass vs size plane. Furthermore, this trend does not depend on the age of their stellar populations. Therefore, such an evolution should involve processes that do not include a significant amount of star formation, leaving (mostly) dry mergers as the main growth channel. By studying close pairs involving a massive galaxy, one can quantify the role of mergers on the growth of massive galaxies. A recent study based on the SHARDS dataset reveals that minor mergers cannot be the dominant mechanism to explain the bulk of size growth in these systems. Merging is found to provide a constant fractional growth rate of ~10% per Gyr from redshift z=1, corresponding to an overall stellar mass increase of 2× between z=1 and z=0.

  17. Islamic Republic of Iran population growth rate declines.

    PubMed

    1996-01-01

    In April 1996, at the 52nd Session of the UN Economic and Social Commission for Asia and the Pacific (ESCAP), the delegate from the Islamic Republic of Iran announced that social indicators indicate acceptable improvement. The average population growth rate fell from 3.9% (1981-1991) to less than 2% (1995). High birth rates and an influx of refugees during 1981-1991 accounted for the high population growth rate. The marked decline in the birth rate, brought about mainly by effective family planning and health programs, has contributed greatly to the reduced population growth rate. The government has focused on rural areas. 86% of rural households now have access to piped water. More than 60% have electricity. The overall literacy rate in Iran has reached 79%. The entire population has access to free or subsidized primary health care services. The Second Development Plan of Iran centers on the significance of the role that mothers have in shaping society and individuals by their child raising abilities, particularly in the early years. The Iranian delegate endorsed the secretariat's plan for helping members and associate members to reach their development goals and objectives. PMID:12291139

  18. Wirth: Key to slowing population growth -- education of girls.

    PubMed

    Fuller, J

    1998-09-01

    The president of the UN Foundation, Tim Wirth, cites education programs for girls as a key to slowing the pace of population growth. Wirth suggests stabilizing the world's population in order to be sure, particularly in the poorest countries, that people have opportunities. The security of the nation and the world hinges upon a sustainable, equitable balance between human numbers and the planet's capacity to support life. Disregarding the issue of population and consumption will destroy the habitat of the world and destroy the very systems that allow life to exist on Earth. The education of girls is a critical area for stabilizing population. Hence, inadequate education is a powerful determinant of high fertility and ensures that individuals do not live up to their potential. The Program of Action adopted at the 1994 ICPD held in Cairo showed that when women have control over their lives, they are better able to contribute to a society that presents them with choices. Conversely, the lack of decision-making power negatively affects a woman's productive role in the family. Wirth also emphasizes the importance of family planning as part of a comprehensive approach to slow population growth. Wirth believes that the Cairo Plus Five Conference to be held in the Hague on February 8-12, 1999, will be very important in making the Program of Action more visible and effective. PMID:12322266

  19. Deterministic versus stochastic aspects of superexponential population growth models

    NASA Astrophysics Data System (ADS)

    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. The Reform of Secondary Education in Indonesia during the 1990s: Basic Education Expansion and Quality Improvement through Curriculum Decentralization.

    ERIC Educational Resources Information Center

    Yeom, Min-Ho; Acedo, Clementina; Utomo, Erry

    2002-01-01

    Case study of two main secondary education reforms in Indonesia in the 1990s: Expansion of basic education and the decentralization of curriculum. Discusses the social, political, and economic trends in the 1990s, context of the secondary education reforms, and the rationale for the reforms. Focuses on the curriculum decentralization design and…

  1. Freshening of the Labrador Sea Surface Waters in the 1990s: Another Great Salinity Anomaly

    NASA Technical Reports Server (NTRS)

    Hakkinen, Sirpa; Koblinsky, Chester J. (Technical Monitor)

    2002-01-01

    Both the observed and simulated time series of the Labrador Sea surface salinities show a major freshening event since the middles. It continues the series of decoder events of the 1970s and 1980s from which the freshening in the early 1970's was named as the Great Salinity Anomaly (GSA). These events are especially distinguishable in the late summer (August and September) time series. The observed data suggests that the 1990's freshening may equal the GSA in magnitude. This recent event is associated with a large reduction in the overturning rate between the early and latter part of the 1990s. Both the observations and model results indicate that the surface salinity conditions appear to be returning towards normal daring 1999 and 2000 in the coastal area, but offshore, the model predicts the freshening to linger on after peaking 1997.

  2. Network integration. A new vision for Catholic healthcare systems in the 1990s.

    PubMed

    Mason, S A

    1990-12-01

    The 1990s will be the decade of network integration for many of the nation's healthcare organizations. Catholic healthcare systems will have to refocus on local and regional healthcare delivery. To succeed in local and regional markets, the systems will have to offer various levels of care through numerous types of providers, share services among facilities, cooperate with secular organizations, and build stronger affiliations with local parishes. Managing this change (from offering fragmented healthcare services to offering integrated services) will be a major challenge facing organizations in the decade ahead. They must develop a clearly articulated vision to provide stability during this time of rapid change. To meet the challenges of the 1990s, Catholic healthcare systems will have to determine the types of functional sharing that will be beneficial at the local level, divest and transfer sponsorship of facilities that burden the system's mission, and expand the activities of the laity. PMID:10108005

  3. A post-1990s assessment of strategic hospital alliances and their marketplace orientations: time to refocus.

    PubMed

    Olden, Peter C; Roggenkamp, Susan D; Luke, Roice D

    2002-01-01

    In past years, many SHAs formed in local urban markets to better compete for managed care contracts. In response to 1990s forces, these SHAs appear to have adapted product, production, and selling orientations to their markets, aimed at large institutional purchasers of health care. However, health care markets have evolved differently than anticipated. SHAs and their hospitals should now adopt the marketing orientation and focus more on patients and enrollees. PMID:11985290

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

    PubMed

    Banguero, H

    1983-05-01

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

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

    PubMed

    Shaw, R P

    1989-01-01

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

  6. Decadal changes in tropical cyclone activity over the western North Pacific in the late 1990s

    NASA Astrophysics Data System (ADS)

    He, Haozhe; Yang, Jing; Gong, Daoyi; Mao, Rui; Wang, Yuqing; Gao, Miaoni

    2015-12-01

    A pronounced decadal change in tropical cyclone (TC) activity over the western North Pacific (WNP) in the late 1990s was identified. Based on a comparison of the two epochs that occurred before and after the late 1990s, the TC genesis number exhibited an evident decrease over the southern WNP (S-WNP: 5°-20°N, 105°-170°E) and an increase over the northern WNP (N-WNP: 20°-25°N, 115°-155°E), which partly corresponded to a significant northward migration in the seasonal mean latitudinal location of TC genesis, i.e., from 17.2°N to 18.7°N. After the late 1990s, the northwestward-moving track became the most dominant track mode, accompanied by the weakening of both the westward-moving track and the northeastward-recurving track. Meanwhile, the TC occurrence frequency (TCF) experienced evident increases over southeastern China and the Okinawa islands, while prominent decreases occurred over the South China Sea, the Philippine Sea, Japan and east of Japan. Changes in the TCF were determined by TC genesis changes, TC track shifts and variations in regional TC durations, which were all ascribed to the decadal change in tropical Indo-Pacific sea surface temperature. The full picture on the decadal changes in the WNP TC activity revealed in this study may provide useful guidance for regional TC seasonal forecasts and future projections.

  7. Stochastic resonance in a generalized Von Foerster population growth model

    SciTech Connect

    Lumi, N.; Mankin, R.

    2014-11-12

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

  8. Stochastic resonance in a generalized Von Foerster population growth model

    NASA Astrophysics Data System (ADS)

    Lumi, N.; Mankin, R.

    2014-11-01

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

  9. Population growth and the changing ecosystem in Mindanao.

    PubMed

    Magdalena, F V

    1996-04-01

    Mindanao is the second largest island in the Philippines. Once considered the greenest spot on earth, it has since been highly exploited. This paper discusses the changing ecosystem of the island as a result of rapid population growth since the early 1900s. Not much is known about Mindanao before 1900. From 1913, however, population grew on Mindanao as the American colonial government established agricultural colonies to open up the south for trade and development. Colonial settlement together with migration and natural population increase led to environmental resource degradation and the displacement of indigenous communities such as the Moros and Lumads. Legal and illegal logging and rampant kaingin agriculture have also stressed the environment. The opening of the Mindanao frontier, Philippine development, the Great Migration, incursion of the Mindanao upland, deforestation, the displacement of indigenous communities, and the possible maintenance and rehabilitation of the ecosystem are discussed. PMID:12292068

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

    NASA Astrophysics Data System (ADS)

    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.

  11. A Portrait of Young Adolescents in the 1990s: Implications for Promoting Healthy Growth and Development.

    ERIC Educational Resources Information Center

    Scales, Peter C.

    Designed to promote the creation of programs and policies that meet the needs of young adolescents, this report considers trends and forces affecting children between the ages of 10 and 15 and offers recommendations for drawing out adolescents' positive possibilities. Section 1 acknowledges trends that point to an increasing number of at-risk…

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

    PubMed

    Meerman, J; Cochrane, S H

    1982-09-01

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

  13. Interspecific synchrony of seabird population growth rate and breeding success

    PubMed Central

    Robinson, James P W; Dornelas, Maria; Ojanguren, Alfredo F

    2013-01-01

    Environmental variability can destabilize communities by causing correlated interspecific fluctuations that weaken the portfolio effect, yet evidence of such a mechanism is rare in natural systems. Here, we ask whether the population dynamics of similar sympatric species of a seabird breeding community are synchronized, and if these species have similar exceptional responses to environmental variation. We used a 24-year time series of the breeding success and population growth rate of a marine top predator species group to assess the degree of synchrony between species demography. We then developed a novel method to examine the species group – all species combined – response to environmental variability, in particular, whether multiple species experience similar, pronounced fluctuations in their demography. Multiple species were positively correlated in breeding success and growth rate. Evidence of “exceptional” years was found, where the species group experienced pronounced fluctuations in their demography. The synchronous response of the species group was negatively correlated with winter sea surface temperature of the preceding year for both growth rate and breeding success. We present evidence for synchronous, exceptional responses of a species group that are driven by environmental variation. Such species covariation destabilizes communities by reducing the portfolio effect, and such exceptional responses may increase the risk of a state change in this community. Our understanding of the future responses to environmental change requires an increased focus on the short-term fluctuations in demography that are driven by extreme environmental variability. PMID:23919147

  14. Population growth and poverty in the developing world.

    PubMed

    Birdsall, N

    1980-12-01

    The links between rapid population growth and the absolute poverty currently affecting 780 million people in the developing countries (excluding China and other centrally planned economies) were examined. Absolute poverty is defined as having less than the income necessary to ensure a daily diet of 2150 calories per person ($200 per person a year in 1970 United States dollars). Focus is on poverty and demography in the developing world (defining poverty; income, fertility and life expectancy; demographic change and poverty), effect of poverty on fertility, family planning programs and the poor, and the outlook for the future. Rapid population growth stretches both national and family budgets thin with the increasing numbers of children to be fed and educated and workers to be provided with jobs. Slower per capita income growth, lack of progress in reducing income inequality, and more poverty are the probable consequences. Many characteristics of poverty can cause high fertility -- high infant mortality, lack of education for women in particular, too little family income to invest in children, inequitable shares in national income, and the inaccessibility of family planning. Experience in China, Indonesia, Taiwan, Colombia, Korea, Sri Lanka, Cuba and Costa Rica demonstrate that birthrates can decline rapidly in low income groups and countries when basic health care, education, and low-cost or free family planning services are made widely available. PMID:12262264

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

    PubMed

    Nash, A E

    1973-01-01

    The 2 themes of this century, increasing environmental fragility and increasing human demands on government, are underlined by the failure of government to effectively govern, and the complex technology and modern communication systems which further divide the developing nations from the developed ones. Population stabilization may help relieve the tension between increasing expectation from government and the fiscal bind in 3 ways: 1)a higher per capita income would increase per capita government revenue which would have a better chance of meeting citizen expectations, 2)a moderately redistributive effect on personal income might occur by decreasing unwanted fertility through the dynamics of economics and increasing the role of government in elevating living standards, and 3)with reduction of government expenditure per capita, the cost of providing any given level of service would decrease. The nuclear age has altered the concept of what constitutes national security. Rapid population growth in the developing countries is also significant, and the United States economy depends on overseas investment. A constructive foreign policy, as opposed to neoimperialism or isolationism, is recommended to help influence world population growth. PMID:4788263

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

    PubMed

    Mays, S; Brickley, M; Ives, R

    2008-05-01

    The rapid urbanization of the Industrial Revolution in 18th-19th century England presented new health challenges. Our aim is to investigate using English skeletal remains whether the living conditions for an urban working class group in the Industrial Revolution negatively impacted upon their skeletal growth compared with a population from a rural agrarian parish. The Industrial Revolution skeletal material is from St Martin's Churchyard, Birmingham (SMB), West Midlands. It dates primarily from the first half of the nineteenth century when Birmingham was a major manufacturing center. The rural group is from Wharram Percy (WP), North Yorkshire, and dates from 10th-19th century AD. The methodology involves plotting diaphyseal bone lengths versus dental age for subadults. No overall difference was found between the two populations in bone length-for-age among the 2- to 18-year cohort. However the younger parts of the SMB cohort were smaller than at WP; the opposite was true of the older parts of the cohort. Growth rate, as inferred from crosssectional data, appeared greater at SMB than at WP. The only result consistent with expectations is the larger bone dimensions in young children from WP, but this likely reflects prolonged breastfeeding at WP not differences in urban and rural environments. That the deleterious health effects that we know accompanied the major transition in human society from a rural agrarian to an urban industrialized living environment should be little manifest in skeletal endochondral growth data is discouraging for those who would use such methodology to monitor health in earlier populations. PMID:18186509

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

    USGS Publications Warehouse

    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

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

    PubMed

    You Poh Seng Rao, B; Shantakumar, G

    1974-01-01

    Social and population policies are considered for the 10 countries comprising Southeast Asia--Burma, Indonesia, the Khmer Republic, Laos, Malaysia, the Philippines, Singapore, Thailand, North Vietnam, and South Vietnam. All but Singapore have high fertility rates and Burma, Indonesia, the Khmer Republic, Laos and the two Vietnams have high mortality rates also. Government expenditures for education and social security systems is expanding throughout the region and it is hoped that their continued growth will contribute substantially to the effective implementation of population policies. Population policies in the 5 countries which have them are discussed. These are Indonesia, Malaysia, the Philippines, Singapore, and Thailand. It is noted, however, that declaration of policy is but the first step. Strategies and programs differ from one country to the next and depend very much on the stage of development, level of literacy, degree of urbanization, and other factors. Family planning activities generally are endogenous to urban social systems but exogenous to rural social systems. Thus, the rural elite has a large role to play in making population policies an integral part of rural life. The possibility is considered of developing workable incentive packages integrating health, education, and social security benefits with suitable emphasis on fertility reduction. PMID:12307191

  19. Herbivory: effects on plant abundance, distribution and population growth

    PubMed Central

    Maron, John L; Crone, Elizabeth

    2006-01-01

    Plants are attacked by many different consumers. A critical question is how often, and under what conditions, common reductions in growth, fecundity or even survival that occur due to herbivory translate to meaningful impacts on abundance, distribution or dynamics of plant populations. Here, we review population-level studies of the effects of consumers on plant dynamics and evaluate: (i) whether particular consumers have predictably more or less influence on plant abundance, (ii) whether particular plant life-history types are predictably more vulnerable to herbivory at the population level, (iii) whether the strength of plant–consumer interactions shifts predictably across environmental gradients and (iv) the role of consumers in influencing plant distributional limits. Existing studies demonstrate numerous examples of consumers limiting local plant abundance and distribution. We found larger effects of consumers on grassland than woodland forbs, stronger effects of herbivory in areas with high versus low disturbance, but no systematic or unambiguous differences in the impact of consumers based on plant life-history or herbivore feeding mode. However, our ability to evaluate these and other patterns is limited by the small (but growing) number of studies in this area. As an impetus for further study, we review strengths and challenges of population-level studies, such as interpreting net impacts of consumers in the presence of density dependence and seed bank dynamics. PMID:17002942

  20. Population growth and land use in Nepal: "the great turnabout".

    PubMed

    Hrabovszky, J P; Miyan, K

    1987-08-01

    Historically, Nepal has demonstrated a "great turnabout" trend, in which initial immigration from the lowland areas to the mountains has been replaced by accelerating migration from the hills to the plains. The reason for this reversal has been a rapid growth in population within the confines of limited availability of potentially cultivable land. Given Nepal's slow economic development, the overwhelming majority of increases in population have to be accommodated within the agricultural sector, on which 83% of Nepal's households are dependent. Fundamental land use issues in Nepal include rapid achievement of the final limit of land suitability for cultivation and the speed at which land can be brought into cultivation. The Government of Nepal has developed the objectives of increased food production to provide a satisfactory diet for the population, increased per capita income, improved regional balance in income and development, conservation of natural resources such as land and forests, and overall development of the economy through income generation, export earnings, and release of agricultural labor to other sectors. 3 perspective studies have identified a number of policies and programs that could bring Nepal closer to these goals. These studies analyzed potential land use development, agricultural production, and food availability by the year 2005. Most essential is the need to intensify land use not only in crop agriculture, but also grasslands and forest use. Land must be allocated to uses that represent the most productive use of that land without being degrading. Technologies are available for land use in each of the main types of uses--crop agriculture, livestock, and forests--that can provide protection against land degradation. Finally, irrigation is a key element in raising agricultural output. Close cooperation between the government and the people is crucial for the success of the task of finding a balance between population growth and its demand

  1. Factors associated with trends in infant and child mortality in developing countries during the 1990s.

    PubMed Central

    Rutstein, S. O.

    2000-01-01

    The 1990s have seen a remarkable decrease in mortality among infants and children in most developing countries. In some countries, particularly in sub-Saharan Africa, these declines in mortality among children have slowed and are now increasing again. Internationally comparable data derived from survey programmes, such as the Demographic and Health Survey (DHS) programme, are available both to document the changes that have occurred in mortality and to provide insight into some of the factors that may explain these trends in mortality. The factors found in repeated DHS programmes that explain these trends fall into five categories: fertility behaviour; nutritional status, breastfeeding, and infant feeding; the use of health services by mothers and for children; environmental health conditions; and socioeconomic status. Both simple analyses and multivariate analyses of changes in these factors between surveys indicate that all factors affected the mortality trends. However, to explain trends in mortality, the variables themselves had to have changed over time. During the 1990s fertility behaviour, breastfeeding, and infant feeding have changed less than other factors and so would seem to have played a smaller role in mortality trends. This study confirms that trends in mortality during the 1990s were related to more than just a handful of variables. It would, therefore, be a mistake to concentrate policy actions on one or a few of these while forsaking others. Countries with the largest decreases in mortality have had substantial improvements in most of the factors that might be used to explain these changes. In some countries mortality has risen. In part these increases can be explained by the factors included in this study, such as deterioration in seeking medical care for children with fever. Other factors that were not measured, such as the increasing resistance of malaria to drug treatment and the increased prevalence of parental HIV/AIDS, may be contributing

  2. Analyses of the lunar surface with advanced remote sensors: Expectations for the 1990's

    NASA Technical Reports Server (NTRS)

    Pieters, Carle M.

    1991-01-01

    Today's advanced sensor capabilities provide unprecedented opportunities for exploration that mesh well with the science requirements for a sophisticated integration of several types of remotely acquired information. Science priorities for the 1990's include an evaluation of the global composition and structure of the primordial lunar crust in order to model its origin and evolution, using the Moon as a natural laboratory to study the impact process and time-cumulative events at 1 AU, and, ultimately, constraining the origin of the Moon and its relation to Earth.

  3. Latin American Social Medicine: Roots, Development During the 1990s, and Current Challenges

    PubMed Central

    Tajer, Débora

    2003-01-01

    Latin American social medicine arose during the 1950s and 1960s, drawing its inspiration from the social movements that emerged in France, Germany, and England in the mid-19th century. The Latin American movement of social medicine has clear ideological goals. It is organized around the Latin American Association of Social Medicine, which was founded in 1984 and is regarded as a social, political, and academic movement. This article takes a historical perspective and presents the reasons for the emergence and identity of the association, focusing on the main developments and contributions of this movement from the 1990s until the present time. PMID:14652326

  4. The architect's framework for ground data system development in the 1990's

    NASA Astrophysics Data System (ADS)

    Ebersole, M. M.

    1990-10-01

    The architect's framework which will describe the myriad of trends and practical conditions that influence the data system architect's design choices in developing the data systems architectures of the 1990's is discussed. The architectural choices are influenced by mission trends, information systems trends, technology trends and practical considerations such as available resources and schedules. These considerations, which will determine architectural choices, are described. A set of guidelines is presented for consideration, based on the recent experience of the author in developing a large scale, distributed system for spacecraft control.

  5. How have hospitals faced the pricing issues of the 1990's?

    PubMed

    Kleimenhagen, A; Naidu, G M; Pillari, G D

    1994-01-01

    National health care expenditures are rising rapidly, bringing on a health care financing crisis. For this reason, it is useful to see how hospitals are facing the price issues of the 1990's. This study examines the price strategies hospitals follow and analyzes their observations on price sensitivity and payer mix. The results clearly show that hospitals have not given much attention to the pricing variable. The study suggests that marketing and finance will have to work closely together in developing future pricing strategies. PMID:10137167

  6. Latin American social medicine: roots, development during the 1990s, and current challenges.

    PubMed

    Tajer, Débora

    2003-12-01

    Latin American social medicine arose during the 1950s and 1960s, drawing its inspiration from the social movements that emerged in France, Germany, and England in the mid-19th century. The Latin American movement of social medicine has clear ideological goals. It is organized around the Latin American Association of Social Medicine, which was founded in 1984 and is regarded as a social, political, and academic movement. This article takes a historical perspective and presents the reasons for the emergence and identity of the association, focusing on the main developments and contributions of this movement from the 1990s until the present time. PMID:14652326

  7. Solid earth science in the 1990s. Volume 1: Program plan

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This is volume one of a three volume series. A plan for solid earth science research for the next decade is outlined. The following topics are addressed: scientific requirements; status of current research; major new emphasis in the 1990's; interagency and international participation; and the program implementation plan. The following fields are represented: plate motion and deformation; lithospheric structure and evolution; volcanology; land surface (processes of change); earth structure and dynamics; earth rotation and reference frames; and geopotential fields. Other topics of discussion include remote sensing, space missions, and space techniques.

  8. Solid Earth science in the 1990s. Volume 3: Measurement techniques and technology

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Reports are contained from the NASA Workshop on Solid Earth Science in the 1990s. The techniques and technologies needed to address the program objectives are discussed. The Measurement Technique and Technology Panel identified (1) candidate measurement systems for each of the measurements required for the Solid Earth Science Program that would fall under the NASA purview; (2) the capabilities and limitations of each technique; and (3) the developments necessary for each technique to meet the science panel requirements. In nearly all cases, current technology or a development path with existing technology was identified as capable of meeting the requirements of the science panels. These technologies and development paths are discussed.

  9. Study of a tracking and data acquisition system for the 1990's. Volume 1: User community characteristics

    NASA Technical Reports Server (NTRS)

    Mccreary, T.

    1981-01-01

    Projected 1990's experiments; navigation requirements and potentials; communications requirements associated with space experiments; alternative forecast options; and operational impacts on experiments are covered. A baseline of plans for the TDAS User Community, including a set of generic experiments developed to supplement existing planning for the 1990's time frame is generated. It includes extensive summaries of collected data, and a bibliography. The data are representative of inputs obtained from NASA planning sources through September 1981.

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

    ERIC Educational Resources Information Center

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

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

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

    NASA Astrophysics Data System (ADS)

    Dumont, E.

    2012-06-01

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

  12. Density but not climate affects the population growth rate of guanacos ( Lama guanicoe) (Artiodactyla, Camelidae).

    PubMed

    Zubillaga, María; Skewes, Oscar; Soto, Nicolás; Rabinovich, Jorge E

    2013-01-01

    We analyzed the effects of population density and climatic variables on the rate of population growth in the guanaco ( Lama guanicoe), a wild camelid species in South America. We used a time series of 36 years (1977-2012) of population sampling in Tierra del Fuego, Chile. Individuals were grouped in three age-classes: newborns, juveniles, and adults; for each year a female population transition matrix was constructed, and the population growth rate (λ) was estimated for each year as the matrix highest positive eigenvalue. We applied a regression analysis with finite population growth rate (λ) as dependent variable, and total guanaco population, sheep population, annual mean precipitation, and winter mean temperature as independent variables, with and without time lags. The effect of guanaco population size was statistically significant, but the effects of the sheep population and the climatic variables on guanaco population growth rate were not statistically significant. PMID:25187878

  13. Density but not climate affects the population growth rate of guanacos ( Lama guanicoe) (Artiodactyla, Camelidae)

    PubMed Central

    Zubillaga, María; Skewes, Oscar; Soto, Nicolás; Rabinovich, Jorge E

    2014-01-01

    We analyzed the effects of population density and climatic variables on the rate of population growth in the guanaco ( Lama guanicoe), a wild camelid species in South America. We used a time series of 36 years (1977-2012) of population sampling in Tierra del Fuego, Chile. Individuals were grouped in three age-classes: newborns, juveniles, and adults; for each year a female population transition matrix was constructed, and the population growth rate (λ) was estimated for each year as the matrix highest positive eigenvalue. We applied a regression analysis with finite population growth rate (λ) as dependent variable, and total guanaco population, sheep population, annual mean precipitation, and winter mean temperature as independent variables, with and without time lags. The effect of guanaco population size was statistically significant, but the effects of the sheep population and the climatic variables on guanaco population growth rate were not statistically significant. PMID:25187878

  14. Population growth: U.S. and Latin American views.

    PubMed

    Hall, M F

    1973-11-01

    Abstract This article is an attempt at interpretation. As one who has worked professionally both in the United States and in Latin America, I would like to interpret how I see the United States and Latin America responding to the high Latin American population growth rate. This is a personal interpretation and as such, of course, is biassed. It is also a very broad subject to which a few pages of interpretation can hardly do justice. The very generalizations 'the United States' and 'Latin America' lend themselves to misunderstanding. These are not homogeneous areas but contain a variety of forces pulling in many directions. And yet, just because this is such a difficult subject as well as such an important one in the world of to-day, it is perhaps worth while to try to distil some common components which may help us gain a better understanding of the actions of others as well as our own. PMID:22091763

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

    PubMed

    Pimentel, D

    1991-01-01

    Destruction of forests and the considerable burning of fossil fuels is directly causing the level of carbon dioxide and other greenhouse gases including methane, carbon monoxide, and nitrous oxide in the atmosphere to rise. Population growth in the US and the world indirectly contributes to this global warming. This has led the majority of scientists interested in weather and climate to predict that the planet's temperature will increase from 1.5 to 4.5 degrees Celsius by 2050. These forecasted climactic changes will most likely strongly affect crop production. Specifically these scientists expect the potential changes in temperature, moisture, carbon dioxide, and pests to decrease food production in North America. The degree of changes hinges on each crop and its environmental needs. If farmers begin using improved agricultural technology, the fall in crop yields can be somewhat counterbalanced. Even without global warming, however, agriculture in North America must embrace sensible ecological resource management practices such as conserving soil, water, energy, and biological resources. These sustainable agricultural practices would serve agriculture, farmers, the environment, and society. Agriculturalists, farmers, and society are already interested in sustainable agriculture. Still scientists must conduct more research on the multiple effects of potential global climate change on many different crops under various environmental conditions and on new technologies that farmers might use in agricultural production. We must cut down our consumption of fossil fuel, reduce deforestation, erase poverty, and protect our soil, water, and biological resources. The most important action we need to take, however, is to check population growth. PMID:12344889

  16. An assessment of bird habitat quality using population growth rates

    USGS Publications Warehouse

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

    2006-01-01

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

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

    PubMed

    Hou, D; Duan, C; Zhang, D

    2000-06-01

    Degradation of forest and grasslands in western China attributes to the soil erosion and desertification in the country. Researchers have established that the primary reason for the degradation of grasslands is overgrazing, which in turn is caused by a number of factors, including over-population and over-reliance on animal husbandry. In addition, the existing administrative system has also proved ineffective in ensuring sustainable development. On contrary, many local governments even encourage exploitative development of grassland; thus, localities opened up grassland for growing crops in an effort to increase income. According to estimates, degraded grassland accounts for more than one-third of utilizable acreage and another one-third suffers from a profusion of rats and pests. To redress the situation, central government should implement strategies in achieving sustainable development, such as providing banking and tax incentives for the development of the secondary and tertiary industries, and supporting education and training of youths from herding areas. Moreover, government should increase spending on infrastructural construction and ecological preservation. Finally, the family planning program needs to be enforced to control population growth and improve the quality of peoples¿ lives. PMID:12322589

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

    PubMed

    Yamaguchi, M; Kennedy, G

    1984-09-01

    The authors measured the positive and negative contributions of population and labor force growth to the growth of per capita income and sectoral output in Japan in the 1880-1970 period. A 2-sector growth accounting model that treats population and labor growth as separate variables was used. 3 alternative methods were used: the Residual method, the Verdoorn method, and the factor augmenting rate method. The total contribution of population cum labor growth to per capita income growth tended to be negative in the 1880-1930 period and positive in the 1930-40 and 1950-70. Over the 1880-1970 period as a whole, population cum labor growth made a positive contribution to per capita income growth under the Residual method (0.35%/year), the factor augmenting rate method (0.29%/year), and the Verdoorn method (0.01%/year). In addition, population cum labor growth contributed positively to sectoral output growth. The average contribution to agricultural output growth ranged from 1.03% (Verdoorn) - 1.46%/year (factor augmenting rate), while the average contribution to nonagricultural output growth ranged from 1.22% (Verdoorn) - 1.60%/year (Residual). Although these results are dependent on the model used, the fact that all 3 methods yielded consistent results suggests that population cum labor growth did make a positive contribution to per capita income and sectoral output growth in Japan. These findings imply that in economies where the rate of technical change in agricultural and nonagricultural sectors exceeds population growth, policies that reduce agricultural elasticities may be preferable; on the other hand, policies that reduce agricultural elasticities are to be avoided in economies with low rates of technical change. Moreover, in the early stages of economic development, policies that increase agricultural income and price elasticities should be considered. PMID:12340109

  19. Population growth and a sustainable environment. The Machakos story.

    PubMed

    Mortimore, M; Tiffen, M

    1994-10-01

    The view is taken that population density in the Machakos District (boundaries prior to 1992) of Kenya influenced both environmental conservation and productivity through adaptation of new technologies. Changes in resource management in Machakos District are identified as a shift to cash crop production, experimentation with staple food options, faster tillage, use of fertilizers for enhancing soil fertility, and livestock and tree cultivation. These agricultural changes occurred due to subdivision of landholdings among sons, private appropriation of scarce grazing land, and land scarcity. Intensive practices such as intensive livestock feeding systems and the permanent manuring of fields increased the efficiency of nutrient cycling through plants, animals, and soils. The Akamba custom gave land rights to those who tilled the soil first. Formal land registration occurred after 1968 and favored owners and investors. Small farm investment was made possible through work off-farm and remittances. The value of output per square kilometer at constant prices increased during 1930-87. Cultivated land area also increased during this period, but mostly on poorer quality land. Agricultural changes were enhanced by social and institutional factors such as small family units and greater partnerships between husband and wife. Families pooled resources through collectives. Women played leadership roles. Competing interest groups and organizations have evolved and enabled people to articulate their needs and obtain access to resources at all levels. These institutions increased in strength over time and with increased density. The cost of service provision decreased with greater population numbers. Development of roads and schools facilitated formal education. Population density, market growth, and a generally supportive economic environment are viewed as the factors responsible for changes in Machakos District. Technological change is viewed as an endogenous process of adaptation

  20. Glimpses of space physics in the 1960s and 1990s

    NASA Astrophysics Data System (ADS)

    Petschek, Harry E.

    1996-05-01

    The author describes his experiences and impressions of space physics in the 1960s and on his return to the field in the 1990s. The field has made significant progress and has changed its operating style to that of a more mature science. It has also become a more closed society with less interaction with outside groups. There is a consequent pessimistic mood including a feeling of lack of progress. The author suggests that the field should become more outwardly oriented. The opportunity presented by present interest in space weather forecasting should be taken seriously by the community as an area of applied science. Additionally, the numerous basic science questions in the field should be viewed in terms of the opportunity of sharing basic discoveries with other parts of the physics community. Examples are given of particular problems where such an outlook will broaden the horizons of space science and allow us to measure our contributions to basic and applied science.

  1. Halo-orbit and lunar-swingby missions of the 1990's

    NASA Technical Reports Server (NTRS)

    Farquhar, Robert W.

    1990-01-01

    A significant number of spacecraft are planning to use halo orbits and lunar-swingby trajectories in the next decade. Four spacecraft will be placed into halo orbits around the earth's sunward libration point, while two others will be stationed near the sun-earth L2 libration point in the distant geomagnetic tail. Six spacecraft, including two of the aforementioned halo orbiters, will make use of lunar-swingby maneuvers to fulfill their mission objectives. Thus, a total of ten spacecraft, five from the Soviet Union, two from Japan, two from the United States, and one from the European Space Agency, will employ halo orbits and/or lunar-swingby trajectories in the 1990's. Pertinent facts are presented for each of these missions.

  2. The NASA cosmic ray program for the 1990's and beyond

    NASA Technical Reports Server (NTRS)

    Ahlen, S. P.; Binns, W. R.; Cherry, M. L.; Gaisser, T. K.; Jones, W. V.; Ling, J. C.; Mewaldt, R. A.; Muller, D.; Ormes, J. O.; Ramaty, R.

    1990-01-01

    The interim report of the 1989 NASA Cosmic Ray Program Working Group is presented. The report summarizes the cosmic ray program for the 1990's, including the recently approved ACE, Astromag, HNC, POEMS, and SAMPEX missions, as well as other key elements of the program. New science themes and candidate missions are identified for the first part of the 21st century, including objectives that might be addressed as part of the Human Exploration Initiative. Among the suggested new thrusts for the 21st century are: an Interstellar Probe into the nearby interstellar medium; a Lunar-Based Calorimeter to measure the cosmic ray composition near 10 exp 16 eV; high-precision element and isotope spectroscopy of ultraheavy elements; and new, more sensitive studies of impulsive solar flare events.

  3. Computer-aided analysis at NASA Langley Research Center - Looking toward the 1990's

    NASA Technical Reports Server (NTRS)

    Petersen, Richard H.

    1985-01-01

    Aerospace research is inextricably intertwined with the programmable digital computer. Engineers and scientists at NASA Langley Research Center are requiring ever-increasing computing resources to carry out basic and applied research on problems and complex systems that would have been unthinkable Just ten years ago. The rapid changes in computer technology make planning for the future especially difficult, even five years in advance. In this paper, the evolution of computer resources and usage in research at Langley are briefly considered over the past thirty years, followed by a snapshot of the present. Finally, an extrapolation to the 1990's computer environment is made, with some thoughts on the tasks that engineers might face, and the background they will probably need.

  4. A data distribution strategy for the 1990s (files are not enough)

    NASA Technical Reports Server (NTRS)

    Tankenson, Mike; Wright, Steven

    1993-01-01

    Virtually all of the data distribution strategies being contemplated for the EOSDIS era revolve around the use of files. Most, if not all, mass storage technologies are based around the file model. However, files may be the wrong primary abstraction for supporting scientific users in the 1990s and beyond. Other abstractions more closely matching the respective scientific discipline of the end user may be more appropriate. JPL has built a unique multimission data distribution system based on a strategy of telemetry stream emulation to match the responsibilities of spacecraft team and ground data system operators supporting our nations suite of planetary probes. The current system, operational since 1989 and the launch of the Magellan spacecraft, is supporting over 200 users at 15 remote sites. This stream-oriented data distribution model can provide important lessons learned to builders of future data systems.

  5. Predicted solar flare activity for the 1990s - Possible effects on navigation systems

    SciTech Connect

    Kunches, J.M.; Hirman, J.W. )

    1990-01-01

    The current solar cycle, which began in September 1986, may prove to be the highest ever, as measured by sunspot numbers and radio flux. The cycle's frequent and strong solar flare activity can be illustrated by the March 1989 episode, which caused many problems for navigation systems. Flares and the geomagnetic storms that sometimes accompany them can disrupt low-frequency systems such as Loran-C, as well as the satellite-borne GPS. Although the maximum of the solar cycle is expected during the first quarter of 1990, flare activity is likely to persist at high levels for a few years to follow. Geomagnetic activity may occur at any time in the cycle, and thus geomagnetic disruptions are possible at any point in the 1990s. 5 refs.

  6. Clinical technology assessment, cost-effective adoption, and quality management by hospitals in the 1990s.

    PubMed

    Veluchamy, S; Saver, C L

    1990-06-01

    Technology assessment in the 1990s must become an integral part of a hospital's strategic priority goals, with active participation of physicians and top management. Technology assessment should involve a wide range of criteria and health care consumer expectations, so that the appropriateness, effectiveness, cost-effectiveness, and quality improvement aspects of new technologies are all considered. Mount Carmel Health's Advanced Treatment and Bionics Institute (ATBI), established in 1986, monitors significant developments in new technologies and performs technology and outcomes assessments. ATBI activities, which have facilitated adoption of 35 treatment-based projects, are integrated into the existing QA structure of Mount Carmel hospitals. Through resolution of identified problems, quality care can be promoted, while providing patients innovative medical treatments. PMID:2120659

  7. A survey of health sciences libraries in hospitals: implications for the 1990s.

    PubMed Central

    Wakeley, P J; Foster, E C

    1993-01-01

    In response to an expressed need for comprehensive data on health sciences libraries in hospitals, the American Hospital Association (AHA) conducted a survey of all U.S. registered hospitals in 1990. The response rate was 57%. Results showed that 2,167 hospitals (31.6% of all U.S. registered hospitals) had on-site libraries that met four definitional criteria. Survey results also indicated that hospitals use diverse resources and approaches to provide information services to a wide array of health care providers and consumers. These baseline data, combined with an assessment of key environmental factors affecting hospitals, can provide guidance to hospital libraries as they face the challenges of the 1990s. The AHA has added the health sciences library to services tracked in its annual survey of hospitals; additional research opportunities in this area remain. PMID:8471998

  8. Tracking and data acquisition system for the 1990's. Volume 7: TDAS space technology assessment

    NASA Technical Reports Server (NTRS)

    Khatri, R.

    1983-01-01

    The results of the TDAS and user spacecraft technology assessment effort are provided. For each TDAS Satellite enhancement and user spacecraft element previously enumerated, the technology issues are identified and the R&D needed to resolve these issues is delineated. Subsequently, taking into account developments taking place elsewhere, the addition unique TDAS satellite module and user spacecraft element R&D efforts needed are identified, and conclusions are drawn in each case. From these conclusions, it is evident that with additional unique R&D efforts carried out for TDAS and appropriate user spacecraft elements the desired TDAS' capabilities for the 1990's can be realized and user spacecraft can be implemented that adequately interface with the projected TDAS.

  9. Health Reform in Ceará: the process of decentralisation in the 1990s

    PubMed Central

    Medeiros, Regianne Leila Rolim; Atkinson, Sarah

    2015-01-01

    The objective of this article is to offer an overview of the health reform in Ceará focusing on the decentralisation process in the 1990s. The driving factor behind the Brazilian health reform movement was the necessity to reorganise the national health system and overcome inequalities. For the reformists, decentralisation, and together with it the idea of popular participation, is seen as essential to guarantee the fulfilment of the people’s needs and to incorporate their voice in the decision-making processes of the health system. In the state of Ceará, after the 1986 elections, health reform movement members took control over the management of the state Health Secretariat. This is the main cause of the acceleration of the decentralisation process with the transference of responsibility over the management of health care delivery to municipalities. PMID:25729333

  10. Tobacco lobby political influence on US state legislatures in the 1990s

    PubMed Central

    Givel, M.; Glantz, S.

    2001-01-01

    BACKGROUND—Throughout the 1990s the tobacco lobby was a potent political force in US state legislatures advancing its pro-tobacco agenda.
OBJECTIVE—To describe the market and political motivations of the tobacco lobby and the strategies they use to achieve these goals in US state legislatures.
DESIGN—This study is a content analysis and summary overview of recently released historical tobacco industry documents; tobacco related government documents; and recent state tobacco control policy reports.
RESULTS—In the 1990s, the tobacco lobby engaged in a comprehensive and aggressive political effort in state legislatures to sell tobacco with the least hindrance using lobbying, the media, public relations, front groups, industry allies, and contributions to legislators. These efforts included campaigns to neutralise clean indoor air legislation, minimise tax increases, and preserve the industry's freedom to advertise and sell tobacco. The tobacco lobby succeeded in increasing the number of states that enacted state pre-emption of stricter local tobacco control laws and prevented the passage of many state tobacco control policies. Public health advocates were able to prevent pre-emption and other pro-tobacco policies from being enacted in several states.
CONCLUSIONS—The tobacco lobby is a powerful presence in state legislatures. Because of the poor public image of the tobacco lobby, it seeks to wield this power quietly and behind the scenes. State and local health advocates, who often have high public credibility, can use this fact against the tobacco lobby by focusing public attention on the tobacco lobby's political influence and policy goals and expose links between the tobacco lobby and its legislative supporters.


Keywords: political lobbying; state legislatures; industry PMID:11387532

  11. Regime shift of the South China Sea SST in the late 1990s

    NASA Astrophysics Data System (ADS)

    Thompson, Bijoy; Tkalich, Pavel; Malanotte-Rizzoli, Paola

    2016-05-01

    Decadal variability of the South China Sea (SCS) sea surface temperature (SST) during 1982-2014 is investigated using observations and ocean reanalysis datasets. The SCS SST shows an abrupt transition from a cold-to-warm regime in the late 1990s. Based on the long-term SST variability two epochs are defined, 1982-1996 and 2000-2014 as cold and warm regimes respectively, spanning on either side of the 1997-1999 SCS warming. Despite the occurrence of strong El Nino induced warming events, the SST anomalies tend to be negative in the cold regime. Conversely during the warm regime, the positive SST anomalies have dominated over the La Nina driven cooling events. The cold (warm) SST regime is marked by net heat gain (loss) by the SCS. The long-term variations of net surface heat flux are mainly driven by the latent heat flux anomalies while the short wave flux plays a secondary role. Low-frequency variability of the South China Sea throughflow (SCSTF) appears to be closely related to the SCS SST regime shift. The SCSTF shows reversing trends during the cold and warm epochs. The weakened SCSTF in the warm regime has promoted the SCS warming by limiting the outward flow of warm water from the SCS. Meanwhile, enhanced SCSTF during the cold regime acts as a cooling mechanism and lead to persistent negative SST anomalies. The change in trend of the SCSTF and SST regime shift coincides with the switching of pacific decadal oscillation from a warm to cold phase in the late 1990s.

  12. A new paradigm for the predominance of standing Central Pacific Warming after the late 1990s

    NASA Astrophysics Data System (ADS)

    Xiang, Baoqiang; Wang, Bin; Li, Tim

    2013-07-01

    Canonical El Niño has a warming center in the eastern Pacific (EP), but in recent decades, El Niño warming center tends to occur more frequently in the central Pacific (CP). The definitions and names of this new type of El Niño, however, have been notoriously diverse, which makes it difficult to understand why the warming center shifts. Here, we show that the new type of El Niño events is characterized by: 1) the maximum warming standing and persisting in the CP and 2) the warming extending to the EP only briefly during its peak phase. For this reason, we refer to it as standing CP warming (CPW). Global warming has been blamed for the westward shift of maximum warming as well as more frequent occurrence of CPW. However, we find that since the late 1990s the standing CPW becomes a dominant mode in the Pacific; meanwhile, the epochal mean trade winds have strengthened and the equatorial thermocline slope has increased, contrary to the global warming-induced weakening trades and flattening thermocline. We propose that the recent predominance of standing CPW arises from a dramatic decadal change characterized by a grand La Niña-like background pattern and strong divergence in the CP atmospheric boundary layer. After the late 1990s, the anomalous mean CP wind divergence tends to weaken the anomalous convection and shift it westward from the underlying SST warming due to the suppressed low- level convergence feedback. This leads to a westward shift of anomalous westerly response and thus a zonally in-phase SST tendency, preventing eastward propagation of the SST anomaly. We anticipate more CPW events will occur in the coming decade provided the grand La Niña-like background state persists.

  13. Cytotoxic human lymphocytes: from in vitro testing (1970s) to immunotherapy (1990s).

    PubMed

    Sinkovics, J; Horvath, J

    1993-01-01

    The senior author was the recipient of a contract (1-CP3-3292) from the National Cancer Institute, USA (NCI) in the early 1970s. The aim of NCI's targeted research program was the establishment of a tumour-specific human lymphocyte-mediated cytotoxicity assay. Neither lymphocyte growth factors nor monoclonal antibodies for lymphocyte typing were available. Tumour-specific populations of lymphocytes could not be maintained but their presence in ficoll-hypaque preparations of blood buffy coats or in primary cultures of tumours was clearly recognized. Another indiscriminately cytotoxic population of lymphocytes had usually overridden the tumour-specific population. In contradistinction to the ruling doctrine of the era, indiscriminately cytotoxic lymphocytes were readily found in the blood of tumour-bearing patients and healthy individuals (the senior author's lymphocytes were shown to practice indiscriminate cytotoxicity in 1971, an observation first interpreted as "immune surveillance at work" in an individual daily exposed to patients with metastatic cancers). Instead of converting the subject matter of the contract from a tumour-specific to a non-specific cytotoxicity assay, the NCI prematurely "phased it out" (but continued the project as intramural research). Nevertheless, many functions of cytotoxic lymphocytes that had become by now well established were foreshadowed during the early 1970s with the limited support of that NCI contract and funds from other sources. Here we recount those early observations; present the outlines of adoptive immunotherapy with various autologous lymphocyte populations and in a separate report in this volume give a technical description how these lymphocyte populations are prepared in the laboratory for therapeutic reinfusions into the patient. PMID:8191863

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

    ERIC Educational Resources Information Center

    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:…

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

  17. Using Spreadsheets To Model Population Growth, Competition and Predation in Nature.

    ERIC Educational Resources Information Center

    Carter, Ashley J. R.

    1999-01-01

    Describes how to place mathematical equations modeling population growth into a spreadsheet that performs calculations quickly and easily. Suggests experiments that can be performed with the spreadsheets. (WRM)

  18. Will there be a 14C minimum in the tropical Pacific in the 1990s

    SciTech Connect

    Toggweiler, J.R. )

    1990-01-09

    14C distributions measured during GEOSECS showed large minima in bomb 14C levels in the tropical belts of the major ocean basins. Broecker et al. (1978, JGR, 83) attributed the minima to upwelling of deep water which was free of bomb 14C. Wyrtki (1981, JPO, 11) countered that heat budgets constrain the water upwelling the the equator to be from the upper themocline. Druffel (1987, JMR, 45) built a model of the Pacific upwelling system incorporating Wyrtki's description of the upwelling system. Druffel showed that the GEOSECS 14C minimum could be reproduced with upwelled upper thermocline water because bomb 14C levels were still relatively low in the tropical thermocline at the time of GEOSECS. Druffel went on to predict that mid latitude and tropical surface 14C levels would approach a common value before the 1990s and upper thermocline water masses acquired more bomb 14C and atmospheric 14C levels declined. By studying pre-bomb coral 14C records and a model simulation in Toggweiler et al. (1989, JGR, 94), I have found confirmation that some older and colder water upwells in the tropical Pacific. Upper thermocline (22-24C) water has about the same pre-bomb 14C content as pre-bomb surface waters and cannot generate a low 14C singal prior to the bomb test. The appearance of the oldest upwelled water in the coral data is correlated in time with the cold phase of the ENSO cycle. Most of the low 14C water moves southward into the South Pacific. I will argue that intensified upwelling during the cold phase of ENSO pulls up 12-14C water from the lower layers of the Equatorial Undercurrent. Upwelling from this layer may represent an important closure mechanism for mode waters formed in the subantarctic. A source of older water makes it certain that the tropical 14C minimum will persist through the 1990s and the remainder of the post-bomb era.

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

    ERIC Educational Resources Information Center

    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…

  20. The World Ocean Circulation Experiment (WOCE): An ocean climatology for the 1990s

    SciTech Connect

    Chapman, P.; Nowlin, W.D. Jr.

    1997-11-01

    During the last ten years, scientists have made remarkable progress in predicting seasonal and interannual climate variability, based on interactions between the atmosphere and the tropical ocean. The goals of the World Ocean Circulation Experiment (WOCE) are to develop models useful for predicting climate variability on longer time scales and to collect the data from the global ocean necessary to test them. Using a variety of instrument platforms, researchers in the US and other nations have been sampling a suite of ocean variables which will be used to build up a climatology of the oceans in the 1990s and from the basis for developing both new models of ocean circulation and coupled models of the ocean and atmosphere. This paper presents some recent results from WOCE research. It includes examples of advances in the fields of sea surface temperature measurements, sea level monitoring, current velocities, upper ocean heat content, and air-sea flux measurements. In addition, we discuss some of the recent advances in modeling and the link between WOCE research and future programs such as CLIVAR, GOOS and GCOS. 27 refs., 2 tabs.

  1. Health policy in the Baltic countries since the beginning of the 1990s.

    PubMed

    Bankauskaite, Vaida; O'Connor, Julia S

    2008-12-01

    The objective of this article is to compare the development of health policies in three Baltic countries, Estonia, Latvia and Lithuania in the period from 1992 to 2004 and reflect on whether key dimensions of these policies are developing in parallel, diverging or even converging in some respects. The paper identifies the similarity in the overall goals and compares the policy content in primary health care, the hospital sector and financing. We conclude that health policy in Estonia, Latvia and Lithuania has been progressing in parallel towards a Western European social insurance funding model, developing a primary care system anchored on a general practitioner service and lessening the hospital orientation of the pre-1990s system. There is evidence of both convergence and divergence across the three countries and of progress in the direction of EU15 in key health policy and outcome characteristics. These patterns are explained partly by differing starting points and partly by political and economic factors over the 1992-2004 period. PMID:18485520

  2. Hydrocarbon occurrences in igneous and metamorphic rocks: Plays of the 1990s

    SciTech Connect

    Harrelson, D.W.

    1989-09-01

    A review of available geologic literature has indicated numerous references detailing the occurrences of hydrocarbon in igneous and metamorphic rocks. Notable among these references is a paper by Chung-Hsiang P'an and a group of papers edited by Sidney Powers. Collectively, these papers conclude a biogenic source for hydrocarbons, most of which occur in (1) weathered igneous and metamorphic reservoir rocks that are higher than the source rocks (e.g., Amarillo field) or (2) igneous and metamorphic rocks that exert structural or stratigraphic control on the reservoir or source rocks (e.g., Jackson dome and the Wiggins anticline-Hancock ridge). It should be noted that a new twist on the abiogenic origin of some inert hydrocarbon gases (i.e., helium and nitrogen) proposes a degassing of igneous and metamorphic rocks from sources in the underlying mantle. Recent european super-deep tests (e.g., the Siljan Ring and the Kola SG-3 testholes) have attempted, with mixed results, to verify this theory. Drilling for these deep igneous and metamorphic prospects today is considered at or below economic basement or worse - a rank wildcat. However, these plays should become increasingly commercial in the 1990s as deeper drilling technology progresses, the current oil glut is eliminated, and more exotic deep gas prospects become accepted.

  3. Epidemiological Study of Japanese Encephalitis Virus in Vientiane, Lao PDR, in 1990s

    PubMed Central

    Saito, Mika; Soukaloun, Douangdao; Phongsavath, Khampe; Phommasack, Bounlay; Makino, Yoshihiro

    2015-01-01

    Phylogenetic analysis of Japanese encephalitis virus (JEV) was conducted using core-premembrane and envelope gene sequence data of two strains from Vientiane, Lao People's Democratic Republic, in 1993 and five from Okinawa, Japan, in 2002 and 2003, and previously published strains. The two Vientiane strains designated as LaVS56 and LaVS145 belonged to genotype 1 (G1) and the same subcluster of G1 as Australian strain in 2000, Thai strains in 1982–1985 and 2004-2005, and Vietnamese strain in 2005, but were distinct from the subcluster of recently distributing G1 strains widely in Asia including Okinawan strains and recent Lao strain in 2009. These clusters with own distinct distributions indicated involvements of different mechanisms and routes of spreading viruses and clarified that Australian G1 strain is from Southeast Asia, not from East Asia. Both Vientiane strains were antigenically close to P19-Br (G1, isolate, Thailand), but distinct from Nakayama (G3, prototype strain, Japan), Beijing-1 (G3, laboratory strain, China), and JaGAr#01 (G3, laboratory strain, Japan), demonstrated by cross-neutralization tests using polyclonal antisera. These results together with seroepidemiologic study conducted in Vientiane strongly suggest that diversified JEV cocirculated there in early 1990s. PMID:25695095

  4. Toward Expanding Tremor Observations in the Northern San Andreas Fault System in the 1990s

    NASA Astrophysics Data System (ADS)

    Damiao, L. G.; Dreger, D. S.; Nadeau, R. M.; Taira, T.; Guilhem, A.; Luna, B.; Zhang, H.

    2015-12-01

    The connection between tremor activity and active fault processes continues to expand our understanding of deep fault zone properties and deformation, the tectonic process, and the relationship of tremor to the occurrence of larger earthquakes. Compared to tremors in subduction zones, known tremor signals in California are ~5 to ~10 smaller in amplitude and duration. These characteristics, in addition to scarce geographic coverage, lack of continuous data (e.g., before mid-2001 at Parkfield), and absence of instrumentation sensitive enough to monitor these events have stifled tremor detection. The continuous monitoring of these events over a relatively short time period in limited locations may lead to a parochial view of the tremor phenomena and its relationship to fault, tectonic, and earthquake processes. To help overcome this, we have embarked on a project to expand the geographic and temporal scope of tremor observation along the Northern SAF system using available continuous seismic recordings from a broad array of 100s of surface seismic stations from multiple seismic networks. Available data for most of these stations also extends back into the mid-1990s. Processing and analysis of tremor signal from this large and low signal-to-noise dataset requires a heavily automated, data-science type approach and specialized techniques for identifying and extracting reliable data. We report here on the automated, envelope based methodology we have developed. We finally compare our catalog results with pre-existing tremor catalogs in the Parkfield area.

  5. Particle astrophysics - The NASA cosmic ray program for the 1990s and beyond

    NASA Technical Reports Server (NTRS)

    Jones, W. V. (Editor); Kerr, Frank J. (Editor); Ormes, Jonathan F. (Editor)

    1990-01-01

    Various papers on particle astrophysics are presented. Individual topics addressed include: the NASA cosmic ray (CR) program for the 1990s and beyond, SAMPEX Mission overview, the Advanced Composition Explorer, Positron Electron Magnet Spectrometer for the Eos Mission, Heavy Nucleus Collector for Space Station, the Astromag Facility, Large Isotope Spectrometer for Astromag, the Solar Probe Mission, the Mercury Dual Orbiter Mission, CRs in the heliosphere, origin of high-energy Galactic CRs, CR studies with the Gamma-Ray Observatory, gamma-ray astronomy at 1 TeV, experimental search for point sources above 1 TeV, the UMC Extensive Air Shower Array, status of the MACRO experiment. Also discussed are: CRs above 1 TeV/n and neutrino astronomy, abundance of ultraheavy nuclei in solar energetic particles, CR studies with an interstellar probe, isotopic composition of CR nuclei beyond the iron peak, experimental studies of CR isotopic composition up to Zr-40, use of accelerators in particle astrophysics, development of long-duration ballooning in Antarctica, Lunar-Based Heavy Nucleus Detector, neutrino astronomy on the moon, gamma rays at airplane altitudes, source composition of CRs.

  6. Evolution of the DSCS phase III satellite through the 1990's

    NASA Astrophysics Data System (ADS)

    Donovan, R.; Kelley, R.; Swimm, K.

    The Defense Satellite Communications Systems (DSCS) initiated its third generation when the first DSCS, Phase III (DSCS III) satellite was successfully launched in late 1982. DSCS III features a multibeam receive nulling antenna, six independent channels and a 10 year lifetime giving better jamming protection, operational flexibility and life cycle costs. DSCS III also supplies AFSATCOM service. During the 1980s DSCS III will incorporate solid state amplifiers, more redundancy, new COMSEC devices, an SHF AFSATCOM downlink, more autonomy and wider channel bandwidths to improve spacecraft reliability and mission performance. By the early 1990s new payloads enhancing mission capabilities are feasible. Possibilities include advanced wideband user and AFSATCOM payloads. The new wideband payload could feature EHF links, adaptive nulling, on-board despreading, and an active transmit array giving higher capacity and jammer protection. The AFSATCOM payload could include EHF and UHF links plus multichannel digital demodulation to give higher jamming protection and capacity in a MILSTAR backup role and EHF telemetry/commanding. Both payloads could utilize satellite crosslinks to improve global netting.

  7. The integration of 1990s thin-film technologies into photovoltaic system design

    NASA Astrophysics Data System (ADS)

    Stolte, W. J.

    1987-05-01

    This report addresses the integration of 1990s timeframe thin-film flat-plate modules into system design. It includes the results of an industry survey to determine the characteristics of such future thin-film modules and the characteristics of a range of postulated module configurations. Impacts on balance-of-plant designs were evaluated for fixed, single-axis tracking and dual-axis tracking arrays in utility-scale plants using postulated low-voltage thin-film module counterparts of present crystalline silicon modules. Intermediate and high-voltage modules more suited to thin-film technology were used in developing plant design modifications to optimally incorporate such future modules. Blocking diode placement, the economics of replacing failed modules, dc field wiring optimization, and additional topics were also addressed. No mechanical or structural design changes were found to be necessary to integrate thin-film modules into existing system designs. Changes to the electrical designs mostly involved slight changes to equipment ratings or panel wiring and were considered to be insignificant. Cost impacts were minor, on the order of one cent per watt. It was found that blocking diode placement should be determined experimentally by the manufacturers, with calculations used only as a guide.

  8. Comparison of in vitro antifungal activities of topical antimycotics launched in 1990s in Japan.

    PubMed

    Nimura, K; Niwano, Y; Ishiduka, S; Fukumoto, R

    2001-08-01

    In vitro anti-dermatophyte, anti-Candida albicans and anti-Malassezia furfur activities of amorolfine hydrochloride (AMF), terbinafine hydrochloride (TBF), butenafine hydrochloride (BTF), neticonazole hydrochloride (NCZ) and ketoconazole (KCZ), all of which were introduced for the treatment of dermatomycoses in the 1990s in Japan, were compared. Although all of the test drugs are classified as an ergosterol biosynthesis inhibitor, the antifungal properties were found to be different. TBF and BTF exerted extremely potent antifungal activity against Trichophyton spp. but not against C. albicans and M. furfur, whilst KCZ and NCZ showed potent antifungal activity against C. albicans and M. furfur rather than Trichophyton spp. AMF exhibited potent antifungal activity against all of the fungal species tested. Fungicidal activities of these antifungal agents against T. rubrum were determined by using neutral red staining. The fungicidal potentialities correlated with those obtained in the in vitro susceptibility test as determined by MICs against dermatophytes. TBF, BTF and AMF exerted more potent fungicidal action than NCZ and KCZ. PMID:11516941

  9. Benchmarks for health expenditures, services and outcomes in Africa during the 1990s.

    PubMed Central

    Peters, D. H.; Elmendorf, A. E.; Kandola, K.; Chellaraj, G.

    2000-01-01

    There is limited information on national health expenditures, services, and outcomes in African countries during the 1990s. We intend to make statistical information available for national level comparisons. National level data were collected from numerous international databases, and supplemented by national household surveys and World Bank expenditure reviews. The results were tabulated and analysed in an exploratory fashion to provide benchmarks for groupings of African countries and individual country comparison. There is wide variation in scale and outcome of health care spending between African countries, with poorer countries tending to do worse than wealthier ones. From 1990-96, the median annual per capita government expenditure on health was nearly US$ 6, but averaged US$ 3 in the lowest-income countries, compared to US$ 72 in middle-income countries. Similar trends were found for health services and outcomes. Results from individual countries (particularly Ethiopia, Ghana, Côte d'Ivoire and Gabon) are used to indicate how the data can be used to identify areas of improvement in health system performance. Serious gaps in data, particularly concerning private sector delivery and financing, health service utilization, equity and efficiency measures, hinder more effective health management. Nonetheless, the data are useful for providing benchmarks for performance and for crudely identifying problem areas in health systems for individual countries. PMID:10916913

  10. Image computing requirements for the 1990s: from multimedia to medicine

    NASA Astrophysics Data System (ADS)

    Gove, Robert J.; Lee, Woobin; Kim, Yongmin; Alexander, Thomas

    1991-05-01

    Although the computer industry has begun incorporating new features in their newest computers and workstations, it has not been clear how best to utilize these new media to improve the productivity of the user. One problem stems from relative separation of various disciplines. For example, three distinct disciplines have evolved from visual information processing: image processing, computer graphics, and pattern recognition. All of them manipulate image data in some ways. The main difference between them is the domain where each discipline takes the input and produces the output. Recognizing the importance of merging the three distinct disciplines into one so that the image data can be successfully incorporated into the future computer technology, a new discipline, denoted as image computing, has been established to provide for consistency and efficiency in managing image data. In conjunction with other technologies such as video and computer-generated audio, image computing will play a key role in developing an integrated information processing platform that will be used in many areas in the 1990s. Some of the areas where image computing technology can be applied are presented. Requirements specific to each application are also described. Functions required of a typical computing workstation will be listed and each requirement will be investigated in detail. We describe how the continuing advances in technology will benefit image computing, and predict how the software algorithms of the future will be employed in image computing. We also introduce some possible future products that incorporate image computing technology.

  11. The effects of invertebrate herbivores on plant population growth: a meta-regression analysis.

    PubMed

    Katz, Daniel S W

    2016-09-01

    Over the last two decades, an increasing number of studies have quantified the effects of herbivory on plant populations using stage-structured population models and integral projection models, allowing for the calculation of plant population growth rates (λ) with and without herbivory. In this paper, I assembled 29 studies and conducted a meta-regression to determine the importance of invertebrate herbivores to population growth rates (λ) while accounting for missing data. I found that invertebrate herbivory often induced important reductions in plant population growth rates (with herbivory, λ was 1.08 ± 0.36; without herbivory, λ was 1.28 ± 0.58). This relationship tended to be weaker for seed predation than for other types of herbivory, except when seed predation rates were very high. Even so, the amount by which studies reduced herbivory was a poor predictor of differences in population growth rates-which strongly cautions against using measured herbivory rates as a proxy for the impact of herbivores. Herbivory reduced plant population growth rates significantly more when potential growth rates were high, which helps to explain why there was less variation in actual population growth rates than in potential population growth rates. The synthesis of these studies also shows the need for future studies to report variance in estimates of λ and to quantify how λ varies as a function of plant density. PMID:27017603

  12. Population Growth and Demographic Structure. Proceedings of the United Nations Expert Group Meeting on Population Growth and Demographic Structure (Paris, France, November 16-20, 1992).

    ERIC Educational Resources Information Center

    United Nations, New York, NY. Dept. of Economic and Social Affairs.

    This volume contains the report and recommendations of the United Nations-sponsored meeting on population growth and demographic structure which was held in Paris, November 1992. Materials in the volume can serve as useful tools for future research on the relations between population, environment, and development and further the work of the United…

  13. Population divergence in compensatory growth responses and their costs in sticklebacks

    PubMed Central

    Ab Ghani, Nurul Izza; Merilä, Juha

    2015-01-01

    Compensatory growth (CG) may be an adaptive mechanism that helps to restore an organisms’ growth trajectory and adult size from deviations caused by early life resource limitation. Yet, few studies have investigated the genetic basis of CG potential and existence of genetically based population differentiation in CG potential. We studied population differentiation, genetic basis, and costs of CG potential in nine-spined sticklebacks (Pungitius pungitius) differing in their normal growth patterns. As selection favors large body size in pond and small body size in marine populations, we expected CG to occur in the pond but not in the marine population. By manipulating feeding conditions (viz. high, low and recovery feeding treatments), we found clear evidence for CG in the pond but not in the marine population, as well as evidence for catch-up growth (i.e., size compensation without growth acceleration) in both populations. In the marine population, overcompensation occurred individuals from the recovery treatment grew eventually larger than those from the high feeding treatment. In both populations, the recovery feeding treatment reduced maturation probability. The recovery feeding treatment also reduced survival probability in the marine but not in the pond population. Analysis of interpopulation hybrids further suggested that both genetic and maternal effects contributed to the population differences in CG. Hence, apart from demonstrating intrinsic costs for recovery growth, both genetic and maternal effects were identified to be important modulators of CG responses. The results provide an evidence for adaptive differentiation in recovery growth potential. PMID:25628860

  14. The Quality of Life of Hong Kong's Poor Households in the 1990s: Levels of Expenditure, Income Security and Poverty

    ERIC Educational Resources Information Center

    Wong, Hung

    2005-01-01

    This paper examines the changes in the quality of life of poor households in Hong Kong in the late 1990s by analyzing their levels of expenditure, income security and poverty before and after 1997. Though there have been significant increases in the levels of expenditure among CSSA recipients, the expenditure among these poorest households in Hong…

  15. The Dynamics of Postsecondary Expansion in the 1990s. Report of the Executive Director. Report 90-12.

    ERIC Educational Resources Information Center

    O'Brien, Kenneth B.

    In this report, the executive director of the California State Postsecondary Education Commission summarizes the major demographic and political forces that will likely affect the shape of higher education leadership in California during the 1990s. The report discusses the implications of increased enrollment pressures on educational equity,…

  16. Massification, Bureaucratization and Questing for "World-Class" Status: Higher Education in China since the Mid-1990s

    ERIC Educational Resources Information Center

    Ngok, Kinglun

    2008-01-01

    Purpose: This article aims to review the latest developments of the higher education sector in China since the mid-1990s by focusing on the expansion of university education. Design/methodology/approach: It is argued that while massification of higher education is an important indication of the progress in China's higher education system, the…

  17. Reconsidering Gender Roles on MTV: Depictions in the Most Popular Music Videos of the Early 1990s.

    ERIC Educational Resources Information Center

    Gow, Joe

    1996-01-01

    Finds that popular music videos of the early 1990s continued to underrepresent women, with men outnumbering women in lead roles by almost a 5 to 1 margin, and presenting women in a much narrower range of lead roles. Finds also that popular music videos portrayed women in a manor that emphasized physical appearance rather than musical ability. (SR)

  18. The Condition of the Diverse Regions of Rural America at the Start of the Decade of the 1990s.

    ERIC Educational Resources Information Center

    Stephens, E. Robert

    This paper constructs a profile of the condition of the diverse areas of rural America at the Beginning of the 1990s. The widely used designation of metropolitan or nonmetropolitan areas based on the metropolitan statistical area (MSA) does not describe the diverse nature of rural America. One alternative typology differentiates nonmetro counties…

  19. Turning Points: Books and Reports that Reflected and Shaped U.S. Education, 1749-1990s.

    ERIC Educational Resources Information Center

    Parker, Franklin

    This document explores a selection influential books and reports on U.S. education that appeared between 1749 and the 1990s. The analysis begins with Benjamin Franklin's "Proposals Relating to the Education of Youth in Pennsylvania", early writings on women's and adult education, the McGuffey reader of the mid-nineteenth century, and Charles…

  20. Constructivism and the Neoliberal Agenda in the Spanish Curriculum Reform of the 1980s and 1990s

    ERIC Educational Resources Information Center

    Rodriguez, Encarna

    2011-01-01

    This article challenges the assumption underlying most education reforms that constructivism is politically neutral and intrinsically democratic. It makes this argument by examining the curriculum reform in Spain during the 1980s and 1990s in light of the neoliberal politics that the country was experiencing at that time. This study employs the…

  1. Budget Blues: The Situation May Not Be Worse than in the Early 1990S, but Public Libraries Are Definitely Hurting

    ERIC Educational Resources Information Center

    Oder, Norman

    2004-01-01

    Public libraries are suffering budget cuts in most states nationwide, according to an informal LJ survey, with a significant segment--though not a majority characterizing the strictures as worse than in the early 1990s, the last time libraries were hit hard. LJ contacted state library agencies and, in some-cases, state library associations, for a…

  2. Development Goals and Strategies for Children in the 1990s. A UNICEF Policy Review. Executive Board Decision 1990-2.

    ERIC Educational Resources Information Center

    United Nations Children's Fund, New York, NY.

    This document presents proposals for goals and strategies for children and development in the 1990s that were approved by the UNICEF Executive Board in April, 1990. The paper proposes that developing human capabilities and meeting basic human needs should be the focus of the UNICEF contribution to the fourth United Nations developmental decade.…

  3. Market Forces in Higher Education--Chinese and British Experience between Mid-1980s and Mid-1990s

    ERIC Educational Resources Information Center

    Zhao, Xiaonan

    2010-01-01

    This paper tries to examine how higher education in China and Britain has been affected by market forces between the mid-1980s and the mid-1990s, from three major issues. Comparing the experiences of both places, the paper argues that unlike the case of British counterpart, where marketisation of education has shifted to a corporate management…

  4. An interdecadal change in the intensity of interannual variability in summer rainfall over southern China around early 1990s

    NASA Astrophysics Data System (ADS)

    Chen, Jiepeng; Wen, Zhiping; Wu, Renguang; Wang, Xin; He, Chao; Chen, Zesheng

    2016-03-01

    The intensity of interannual variability (IIV) in southern China (SC) summer rainfall experienced a remarkable increase in early 1990s, concurrent with the interdecadal increase in SC summer rainfall. Two factors are proposed for this interdecadal change. One is the interdecadal increase of IIV in tropical eastern Indian Ocean (TEIO) sea surface temperature (SST) after early 1990s. Anomalous warmer (cooler) TEIO SST triggers anomalous ascending (descending) motion and lower-level cyclonic (anticyclone) circulation in situ, which in turn induces anomalous descent (ascent) over SC through an anomalous meridional vertical circulation. This contributes to interannual summer rainfall variability over SC. The increase in the amplitude of TEIO SST anomalies in early 1990s led to an intensified interannual variability of summer rainfall over SC. The other is the strengthened influence of a coupled mode of the North Atlantic Oscillation (NAO) and North Atlantic triple SST anomaly on interannual variability in summer rainfall over SC after early 1990s. The leading EOF mode of the North Atlantic SST is characterized by a stripe pattern during 1979-1992, while during 1993-2008 the dominant mode of the North Atlantic SST is a triple pattern. The triple pattern of North Atlantic SST may exert positive effect on the NAO after early 1990s. Compared to the period 1979-1992, the relationship between the NAO and interannual summer rainfall over SC is enhanced during 1993-2008. The NAO coupled with North Atlantic SST triple exerts an important impact on SC summer rainfall variability through Eurasian wave-like train.

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

    PubMed

    Shelton, James D

    2014-05-01

    Reduced mortality has been the predominant cause of the marked global population growth over the last 3/4 of a century. While improved child survival increases motivation to reduce fertility, it comes too little and too late to forestall substantial population growth. And, beyond motivation, couples need effective means to control their fertility. It is an inconvenient truth that reducing child mortality contributes considerably to the population growth destined to compromise the quality of life of many, particularly in sub-Saharan Africa. Vigorous child survival programming is of course imperative. Wide access to voluntary family planning can help mitigate that growth and provide many other benefits. PMID:25276571

  6. Population level consequences of toxicological influences on individual growth and reproduction in Lumbricus rubellus (Lumbricidae, Oligochaeta).

    PubMed

    Klok, C; de Roos, A M

    1996-03-01

    The effects of increased environmental concentrations of copper on the population dynamics of Lumbricus rubellus are investigated. A size-structured matrix model is used to translate sublethal effects on individual growth and reproduction into their population dynamical consequences. Laboratory data on growth and reproduction under different, sublethal conditions of copper stress are used to parameterize the model. An estimate for the critical threshold concentration of copper (critical in a sense that the population growth rate at this concentration equals zero), obtained from the model analysis, agrees well with observations on field populations of L. rubellus. PMID:8723748

  7. Dynamics of single-species population growth: stability or chaos

    SciTech Connect

    Mueller, L.D.; Ayala, F.J.

    1981-01-01

    We have examined stability at the carrying capacity for 25 genetically different populations of Drosophila melanogaster. In spite of their genetic heterogeneity, 20 of the populations yield stable equilibria and none have eigenvalues significantly greater than one. Computer simulations demonstrate how selection at the individual level may account for population stability (and, hence, that group selection is not necessary for the evolution of stability). Recent theoretical studies on density-dependent selection in random environments provide predictions consistent with our empirical findings.

  8. Understanding Rural Population Loss.

    ERIC Educational Resources Information Center

    McGranahan, David A.; Beale, Calvin L.

    2002-01-01

    A quarter of nonmetro counties lost population in the 1990s, but population loss was not related to poverty rate or low educational levels, perhaps because low-skill workers can no longer expect better wages in urban areas. Population loss was related to low population density and remoteness (which decrease access to services), lack of natural…

  9. History of regulatory requirements for poultry biologics in the United States, 1970s to 1990s.

    PubMed

    Espeseth, David A; Lasher, Hiram

    2013-06-01

    By the end of the 1960s, The United States Department of Agriculture (USDA) had established the basic purity and safety standards for poultry biologics in the United States and had licensed products to address many of the major poultry diseases of concern at that time. The emergence of new diseases, advances in scientific technology, and changes in poultry husbandry practices that occurred in the 1970s to the 1990s required the development of many new and amended regulatory requirements to keep abreast of the changing needs of the poultry industry. Veterinary Services often approved the use of special or conditional licensing procedures to shorten the time to license products needed to address emerging diseases. Infectious bronchitis, bursal disease, fowl cholera, duck virus enteritis, avian influenza, and other vaccines were rapidly licensed to address emerging disease problems using this procedure. Changes in labeling and packaging requirements were made to address changing vaccination practices. Veterinary Services permitted diluents to be shipped separate from product, first for Marek's disease vaccine and later for vaccines recommended for administration by automatic vaccinating machines. The maximum number of doses permitted to be in one container and package were also amended to address the increased size of poultry flocks. Veterinary Services also approved the use of split manufacturing procedures that permitted two or more licensed manufacturers to work together in the production of a product. This innovative use of licensing products for further manufacture allowed the industry to use production facilities more efficiently and provided a wider variety of combination products. In 1985, Congress passed an amendment to the Virus-Serum-Toxin Act that gave USDA the authority to regulate all veterinary biological products shipped in or from the United States. This amendment brought intrastate biologics manufacturers under federal jurisdiction and ensured all

  10. A Photometer for Measuring Population Growth in Yeast.

    ERIC Educational Resources Information Center

    Tatina, Robert; Hartley, Tamela; Thomas, Danita

    1999-01-01

    Describes the construction and use of an inexpensive, portable photometer designed specifically for estimating population sizes in yeast cultures. Suggests activities for use with the photometer. (WRM)

  11. Increased frequency of wintertime stratification collapse events in the Gulf of Finland since the 1990s

    NASA Astrophysics Data System (ADS)

    Elken, Jüri; Raudsepp, Urmas; Laanemets, Jaan; Passenko, Jelena; Maljutenko, Ilja; Pärn, Ove; Keevallik, Sirje

    2014-01-01

    Since the 1990s, an increased frequency of stratification collapse events in the Gulf of Finland has been noticed, when the density difference between near-bottom and surface waters fell below 0.5 kg m- 3. Such stratification crashes occur in the winter months, from October-November to March-April, when saline and thermal stratification decrease compared to the summer period according to the well-known seasonal cycle. The stratification decay process is forced primarily by (1) the westerly-southwesterly wind stress, which causes anti-estuarine straining, and (2) direct wind mixing proportional to the wind speed cubed. The potential energy anomaly (PEA) is occasionally reduced from the average winter level of 70 J m- 3 (per unit volume; 4.9 kJ m- 2 per unit area of 70-m water column) to nearly zero, manifesting the stratification collapse, when the current-straining work and wind-mixing work significantly exceed their average levels. Increased collapse frequency is caused by the shift of wind forcing. Namely, the average bimonthly cumulative westerly-southwesterly wind stress in December and January has increased from 1.7 N m- 2 d during 1962-1988 to 3.7 N m- 2 d during 1989-2007, yielding a reduction in PEA during these two winter months of about 4.4 kJ m- 2 between the periods. The other component of the reduction in PEA, wind mixing work per unit surface area, has also increased by 4.6 kJ m- 2 since 1999 for these two months.

  12. Density estimation and population growth of mosquitofish (Gambusia affinis) in rice fields.

    PubMed

    Stewart, R J; Miura, T

    1985-03-01

    Mark-release-recapture estimation of population density was performed with mosquitofish in a rice field habitat. Regression analysis showed a relationship between absolute density and mean number of fish per trap. Trap counts were converted to density estimates with data from several fields and growth curves were calculated to describe seasonal growth of mosquitofish populations at three different initial stocking rates. The calculated curves showed a good correspondence to field populations of mosquitofish. PMID:2906659

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

    ERIC Educational Resources Information Center

    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…

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

    PubMed

    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. PMID:26003308

  15. THE EFFECT OF RANDOM VARIATIONS OF DIFFERENT TYPES ON POPULATION GROWTH

    PubMed Central

    Levins, R.

    1969-01-01

    The probability distributions of population size are derived for populations living in randomly varying environments for both density-dependent and density-independent population growth. The effects of random variation in the rate of increase, the carrying capacity, and sampling variation in numbers are examined. PMID:5256407

  16. Black Population Distribution and Growth in the United States. Geography Curriculum Project.

    ERIC Educational Resources Information Center

    Pelletti, John C.

    The self-study unit for intermediate grades deals with growth and distribution of the black population of the United States. The unit shows how and why the black population started from a rural southern base and became a largely urban population, compares the black people of two cities, one northern and one southern, and discusses how they are…

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

    PubMed

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

    2012-01-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed Central

    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. PMID:26039073

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

    PubMed

    Weiner, J; Kinsman, S; Williams, S

    1998-11-01

    We studied the growth of individual Xanthium strumarium plants growing at four naturally occurring local densities on a beach in Maine: (1) isolated plants, (2) pairs of plants ≤1 cm apart, (3) four plants within 4 cm of each other, and (4) discrete dense clumps of 10-39 plants. A combination of nondestructive measurements every 2 wk and parallel calibration harvests provided very good estimates of the growth in aboveground biomass of over 400 individual plants over 8 wk and afforded the opportunity to fit explicit growth models to 293 of them. There was large individual variation in growth and resultant size within the population and within all densities. Local crowding played a role in determining plant size within the population: there were significant differences in final size between all densities except pairs and quadruples, which were almost identical. Overall, plants growing at higher densities were more variable in growth and final size than plants growing at lower densities, but this was due to increased variation among groups (greater variation in local density and/or greater environmental heterogeneity), not to increased variation within groups. Thus, there was no evidence of size asymmetric competition in this population. The growth of most plants was close to exponential over the study period, but half the plants were slightly better fit by a sigmoidal (logistic) model. The proportion of plants better fit by the logistic model increased with density and with initial plant size. The use of explicit growth models over several growth intervals to describe stand development can provide more biological content and more statistical power than "growth-size" methods that analyze growth intervals separately. PMID:21680325

  1. Future population growth: researchers in three countries quantify causes and propose policies.

    PubMed

    1997-01-01

    This article discusses Population Council analyses conducted by social scientists from India, Kenya, and the Philippines. These scientists agreed that population momentum would continue to increase population size, and that governments must strengthen and create a range of economic, health, and social programs and policies to slow population growth. Multiple approaches will be needed. John Bongaarts is credited with being the first to identify the key role of population momentum and to decompose growth into unwanted fertility, high desired fertility, and population momentum. Unwanted fertility is responsible for about 19% of projected population growth in India, 26% in Kenya, and 16% in the Philippines. High wanted fertility accounts for 20% of future growth in India, 6% in Kenya, and 19% in the Philippines. Population momentum can account for under 50% or over 90% of growth. Unwanted fertility can be addressed by fulfilling unmet need and increasing knowledge of methods, reducing the fear of side effects and disapproval, and eliminating poor service. Family planning programs need to be strengthened and integrated with maternal and child health services. Preferred and actual family sizes can be reduced by lowering infant mortality by means of increasing infant and child health services and girls' educational attainment. Population momentum can be addressed by delaying age at marriage and childbearing through improving social conditions. Investments in human development through education, training, and income generation can create the conditions for slowing population growth. Countries should decompose population growth into its components of unwanted and high wanted fertility and population momentum as a means of distributing resources most effectively. PMID:12292641

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

    PubMed

    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. PMID:17714273

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

    PubMed

    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. PMID:12315554

  4. Reconstructing the dynamics of ancient human populations from radiocarbon dates: 10 000 years of population growth in Australia

    PubMed Central

    Johnson, Christopher N.; Brook, Barry W.

    2011-01-01

    Measuring trends in the size of prehistoric populations is fundamental to our understanding of the demography of ancient people and their responses to environmental change. Archaeologists commonly use the temporal distribution of radiocarbon dates to reconstruct population trends, but this can give a false picture of population growth because of the loss of evidence from older sites. We demonstrate a method for quantifying this bias, and we use it to test for population growth through the Holocene of Australia. We used model simulations to show how turnover of site occupation across an archaeological landscape, interacting with erasure of evidence at abandoned sites, can create an increase in apparent site occupation towards the present when occupation density is actually constant. By estimating the probabilities of abandonment and erasure from archaeological data, we then used the model to show that this effect does not account for the observed increase in occupation through the Holocene in Australia. This is best explained by population growth, which was low for the first part of the Holocene but accelerated about 5000 years ago. Our results provide new evidence for the dynamism of non-agricultural populations through the Holocene. PMID:21561972

  5. Reconstructing the dynamics of ancient human populations from radiocarbon dates: 10 000 years of population growth in Australia.

    PubMed

    Johnson, Christopher N; Brook, Barry W

    2011-12-22

    Measuring trends in the size of prehistoric populations is fundamental to our understanding of the demography of ancient people and their responses to environmental change. Archaeologists commonly use the temporal distribution of radiocarbon dates to reconstruct population trends, but this can give a false picture of population growth because of the loss of evidence from older sites. We demonstrate a method for quantifying this bias, and we use it to test for population growth through the Holocene of Australia. We used model simulations to show how turnover of site occupation across an archaeological landscape, interacting with erasure of evidence at abandoned sites, can create an increase in apparent site occupation towards the present when occupation density is actually constant. By estimating the probabilities of abandonment and erasure from archaeological data, we then used the model to show that this effect does not account for the observed increase in occupation through the Holocene in Australia. This is best explained by population growth, which was low for the first part of the Holocene but accelerated about 5000 years ago. Our results provide new evidence for the dynamism of non-agricultural populations through the Holocene. PMID:21561972

  6. How Population Growth and Land-Use Change Increased Fluvial Dissolved Organic Carbon Fluxes over 130 Years in the Thames Basin (UK)

    NASA Astrophysics Data System (ADS)

    Noacco, V.; Howden, N. J. K.; Wagener, T.; Worrall, F.; Burt, T. P.

    2015-12-01

    This study investigates drivers of changing dissolved organic carbon (DOC) export in the UK's River Thames basin between 1884 and 2014. Specifically, we consider how the impacts of land-use change and population growth drive increases in DOC concentrations and fluxes at the basin outlet. Such key factors for the long-term increase in riverine DOC in temperate, mineral-soil catchments are still widely debated. First, we estimate soil organic carbon (SOC) stocks in the Thames basin for the period. Second, we convert SOC losses due to land-use change into DOC loss to surface waters through runoff. Finally, we combine this input of DOC with an export coefficient model that considers catchment drivers for DOC release to the river. SOC stocks for each year are calculated from a large database of typical SOC levels for land-uses present in the Thames basin and are combined with literature values of transition times for SOC to adjust to a new level following land-use change. We also account for climate change effects on SOC stock due to temperature increases, which reduces SOC stocks as soil organic matter turnover rates increase. Our work shows that the major driver for DOC increase to the river Thames was the rise in the catchment population, where the increase in urban area was used as a proxy. This highlights the role of sewage effluent in contributing to the rise of fluvial DOC, even though wastewater treatments were in place since the early 1990s. Land-use change had significant but short-term impacts in the increase in DOC, mainly due to massive conversion of permanent grassland into arable land during World War II.

  7. Australia's Youth: Reality and Risk. A National Perspective on Developments That Have Affected 15-19 Year Olds during the 1990s.

    ERIC Educational Resources Information Center

    Dusseldorp Skills Forum, Inc., Sydney (Australia).

    This first annual report by the Dusseldorp Skills Forum on the situation of young Australians provides a national perspective on developments that have affected 15-19 year olds during the 1990s. An overview chapter, "Youth: The Rhetoric and the Reality of the 1990s" (Richard Sweet), addresses these topics: education-work transition; the labor…

  8. Concept to Reality: Contributions of the Langley Research Center to US Civil Aircraft of the 1990s

    NASA Technical Reports Server (NTRS)

    Chambers, Joseph R.

    2003-01-01

    This document is intended to be a companion to NASA SP-2000-4519, 'Partners in Freedom: Contributions of the Langley Research Center to U.S. Military Aircraft of the 1990s'. Material included in the combined set of volumes provides informative and significant examples of the impact of Langley's research on U.S. civil and military aircraft of the 1990s. This volume, 'Concept to Reality: Contributions of the NASA Langley Research Center to U.S. Civil Aircraft of the 1990s', highlights significant Langley contributions to safety, cruise performance, takeoff and landing capabilities, structural integrity, crashworthiness, flight deck technologies, pilot-vehicle interfaces, flight characteristics, stall and spin behavior, computational design methods, and other challenging technical areas for civil aviation. The contents of this volume include descriptions of some of the more important applications of Langley research to current civil fixed-wing aircraft (rotary-wing aircraft are not included), including commercial airliners, business aircraft, and small personal-owner aircraft. In addition to discussions of specific aircraft applications, the document also covers contributions of Langley research to the operation of civil aircraft, which includes operating problems. This document is organized according to disciplinary technologies, for example, aerodynamics, structures, materials, and flight systems. Within each discussion, examples are cited where industry applied Langley technologies to specific aircraft that were in operational service during the 1990s and the early years of the new millennium. This document is intended to serve as a key reference for national policy makers, internal NASA policy makers, Congressional committees, the media, and the general public. Therefore, it has been written for a broad general audience and does not presume any significant technical expertise. An extensive bibliography is provided for technical specialists and others who desire a

  9. Commodities consumed in Italy, Greece and other Mediterranean countries compared with Australia in 1960s and 1990s.

    PubMed

    Noah, Ann; Truswell, Stewart

    2003-01-01

    Consumption figures for 15 major commodities (cereals, wheat, rice, maize, potato, pulses, olive oil, other vegetable oils, vegetables, fruits, wine, meats, animal fats, milk + products, and fish + seafood) were collected from FAO Food Balance Sheets during the 1960s (1961-1969) and late 1990s (1995-1999). For some nutritionists the "model Mediterranean diet" is the Italian or Greek diet of the 1960s, for others the concept of Mediterranean countries is more general. Analysis shows: (1) In the 1960s, Australia consumed more meat, milk, animal fat than Italy or Greece and less cereals, wheat, pulses, olive oil, vegetables, fruits and wine. (2) In the 1960s, Australia's olive oil, vegetables, fruits and wine consumption were within the range for all 18 Mediterranean countries (i.e. Spain, France, Italy, Malta, Croatia, Bosnia, Albania, Greece, Cyprus, Turkey, Syria, Lebanon, Israel, Egypt, Libya, Tunisia, Algeria and Morocco). (3) In the 1990s, food consumptions have evolved; Australia's wine and milk consumption is now similar to Italy and Greece; consumption of wheat, olive oil, vegetables, fruits and fish are lower; consumption of potato, pulses, other vegetable oils and meat are higher than Italy or Greece. (4) Australia's consumption of the 15 commodities is within the range of all Mediterranean countries in the late 1990s, except wheat consumption was lower. PMID:12737007

  10. Contribution of the phase transition of Pacific Decadal Oscillation to the late 1990s' shift in East China summer rainfall

    NASA Astrophysics Data System (ADS)

    zhu, yali

    2016-04-01

    Based on our previous study, the interdecadal changes in summer rainfall over East China in the late 1990s are further explored here. The increased local rising motion is implicated as the dominant factor of increased rainfall in the lower Huang-Huai River valley (LHR). Both the observation and numerical experiments using Community Atmosphere Model, version 4 suggest that the negative Pacific Decadal Oscillation (PDO) mode can result in rising anomalies and thus more rainfall in the LHR. The East Asian westerly jet stream (EAWJS) is suggested as a bridge to link the Pacific sea surface temperature anomalies and East Asian summer rainfall. Model results reveal that the negative PDO mode can lead to significant easterly anomalies over East Asia. As a result, the EAWJS is weakened and shifts poleward, which coincides with observed changes in EAWJS after the late 1990s. In addition, weakened and poleward shifted EAWJS can result in an anomalous ascending motion to its south (in the LHR) by modulating the jet-related secondary meridional-vertical circulation. Consequently, rainfall increased in the LHR after the late 1990s. Besides, the positive Atlantic Meridional Oscillation can only induce insignificant changes over East Asia and partly counteract the negative PDO effect there.

  11. Student-Teacher Population Growth Model. Working Paper.

    ERIC Educational Resources Information Center

    Zabrowski, Edward K.; And Others

    This mathematical model of the educational system calculates information on population groups by sex, race, age, and educational level. The model can be used to answer questions about what would happen to the flows of students and teachers through the formal educational system if these flows are changed at various stages. The report discusses the…

  12. Calculating the Financial Impact of Population Growth on Education.

    ERIC Educational Resources Information Center

    Cline, Daniel H.

    It is particularly difficult to make accurate enrollment projections for areas that are experiencing a rapid expansion in their population. The traditional method of calculating cohort survival ratios must be modified and supplemented with additional information to ensure accuracy; cost projection methods require detailed analyses of current costs…

  13. World Bank Atlas: Population, Per Capita Product and Growth Rates.

    ERIC Educational Resources Information Center

    World Bank, Washington, DC.

    The ninth edition of the World Bank Atlas shows estimates of population, gross national product, and per capita production of 189 countries and territories for 1972. The data presented in the atlas are the result of the work of the World Bank Group whose major purpose is to provide both financial and technical assistance and to improve the living…

  14. Trophic interactions and population growth rates: describing patterns and identifying mechanisms.

    PubMed Central

    Hudson, Peter J; Dobson, Andy P; Cattadori, Isabella M; Newborn, David; Haydon, Dan T; Shaw, Darren J; Benton, Tim G; Grenfell, Bryan T

    2002-01-01

    While the concept of population growth rate has been of central importance in the development of the theory of population dynamics, few empirical studies consider the intrinsic growth rate in detail, let alone how it may vary within and between populations of the same species. In an attempt to link theory with data we take two approaches. First, we address the question 'what growth rate patterns does theory predict we should see in time-series?' The models make a number of predictions, which in general are supported by a comparative study between time-series of harvesting data from 352 red grouse populations. Variations in growth rate between grouse populations were associated with factors that reflected the quality and availability of the main food plant of the grouse. However, while these results support predictions from theory, they provide no clear insight into the mechanisms influencing reductions in population growth rate and regulation. In the second part of the paper, we consider the results of experiments, first at the individual level and then at the population level, to identify the important mechanisms influencing changes in individual productivity and population growth rate. The parasitic nematode Trichostrongylus tenuis is found to have an important influence on productivity, and when incorporated into models with their patterns of distribution between individuals has a destabilizing effect and generates negative growth rates. The hypothesis that negative growth rates at the population level were caused by parasites was demonstrated by a replicated population level experiment. With a sound and tested model framework we then explore the interaction with other natural enemies and show that in general they tend to stabilize variations in growth rate. Interestingly, the models show selective predators that remove heavily infected individuals can release the grouse from parasite-induced regulation and allow equilibrium populations to rise. By contrast, a

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

    PubMed

    Roland, Jens; Matter, Stephen F

    2013-01-01

    We examined the long-term, 15-year pattern of population change in a network of 21 Rocky Mountain populations of Parnassius smintheus butterflies in response to climatic variation. We found that winter values of the broadscale climate variable, the Pacific Decadal Oscillation (PDO) index, were a strong predictor of annual population growth, much more so than were endogenous biotic factors related to population density. The relationship between PDO and population growth was nonlinear. Populations declined in years with extreme winter PDO values, when there were either extremely warm or extremely cold sea surface temperatures in the eastern Pacific relative to that in the western Pacific. Results suggest that more variable winters, and more frequent extremely cold or warm winters, will result in more frequent decline of these populations, a pattern exacerbated by the trend for increasingly variable winters seen over the past century. PMID:23600253

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

    PubMed

    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

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

    PubMed

    Tabutin, D; Thiltges, E

    1992-01-01

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

  18. A Waste of Resources? Social Rates of Return to Higher Education in the 1990s.

    ERIC Educational Resources Information Center

    Ashworth, John

    1998-01-01

    Demonstrates that popular assertions regarding the social benefits of additional higher education are dubious. Reveals four decisive factors: presumed economic growth; changes in graduates' and nongraduates' relative earnings; differences between the marginal and average student; and belief in scale economies. Unless economic growth favors…

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

    USGS Publications Warehouse

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

    2007-01-01

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

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

    PubMed

    Zhu, J

    1995-01-01

    In this study of the growth in population and industry in Shanghai, China, between the 1982 and 1990 censuses, data on administrative divisions was normalized through digitization and spatial analysis. Analysis focused on spatial units, intensity of growth, time period, distance, rate of growth, and direction of spatial growth. The trisection method divided the city into city proper, outskirts, and suburbs. The distance function method considered the distance from center city as a function: exponential, power, trigonometric, logarithmic, and polynomial. Population growth and employment in all sectors increased in the outskirts and suburbs and decreased in the city proper except tertiary sectors. Primary sector employment decreased in all three sections. Employment in the secondary increased faster in the outskirts and suburbs than the total rate of growth of population and employment. In the city secondary sector employment rates decreased faster than total population and employment rates. The tertiary sector had the highest rate of growth in all sections, and employment grew faster than secondary sector rates. Tertiary growth was highest in real estate, finance, and insurance. Industrial growth in the secondary sector was 160.2% in the suburbs, 156.6% in the outskirts, and 80.9% in the city. In the distance function analysis, industry expanded further out than the entire secondary sector. Commerce grew the fastest in areas 15.4 km from center city. Economic growth was faster after economic reforms in 1978. Growth was led by industry and followed by the secondary sector, the tertiary sector, and population. Industrial expansion resulted from inner pressure, political factors controlling size, the social and economic system, and the housing construction and distribution system. Initially sociopsychological factors affected urban concentration. PMID:12288964

  1. Temporal association between childhood leukaemia and population growth in Swiss municipalities.

    PubMed

    Lupatsch, Judith E; Kreis, Christian; Zwahlen, Marcel; Niggli, Felix; Ammann, Roland A; Kuehni, Claudia E; Spycher, Ben D

    2016-08-01

    The population mixing hypothesis proposes that childhood leukaemia (CL) might be a rare complication of a yet unidentified subclinical infection. Large population influxes into previously isolated rural areas may foster localised epidemics of the postulated infection causing a subsequent increase of CL. While marked population growth after a period of stability was central to the formulation of the hypothesis and to the early studies on population mixing, there is a lack of objective criteria to define such growth patterns. We aimed to determine whether periods of marked population growth coincided with increases in the risk of CL in Swiss municipalities. We identified incident cases of CL aged 0-15 years for the period 1985-2010 from the Swiss Childhood Cancer Registry. Annual data on population counts in Swiss municipalities were obtained for 1980-2010. As exposures, we defined (1) cumulative population growth during a 5-year moving time window centred on each year (1985-2010) and (2) periods of 'take-off growth' identified by segmented linear regression. We compared CL incidence across exposure categories using Poisson regression and tested for effect modification by degree of urbanisation. Our study included 1500 incident cases and 2561 municipalities. The incident rate ratio (IRR) comparing the highest to the lowest quintile of 5-year population growth was 1.18 (95 % CI 0.96, 1.46) in all municipalities and 1.33 (95 % CI 0.93, 1.92) in rural municipalities (p value interaction 0.36). In municipalities with take-off growth, the IRR comparing the take-off period (>6 % annual population growth) with the initial period of low or negative growth (<2 %) was 2.07 (95 % CI 0.95, 4.51) overall and 2.99 (1.11, 8.05) in rural areas (p interaction 0.52). Our study provides further support for the population mixing hypothesis and underlines the need to distinguish take-off growth from other growth patterns in future research. PMID:27251152

  2. Inverse problem for the Verhulst equation of limited population growth with discrete experiment data

    NASA Astrophysics Data System (ADS)

    Azimov, Anvar; Kasenov, Syrym; Nurseitov, Daniyar; Serovajsky, Simon

    2016-08-01

    Verhulst limited growth model with unknown parameters of growth is considered. These parameters are defined by discrete experiment data. This inverse problem is solved with using gradient method with interpolation of data and without it. Approximation of the delta-function is used for the latter case. As an example the bacteria population E.coli is considered.

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

    ERIC Educational Resources Information Center

    Morrison, Peter A.; Wheeler, Judith P.

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

  4. SUITABILITY OF SELECTED CROPS AND SOIL FOR GARDEN SYMPHYLAN (SYMPHYLA, SCUTIGERELLIDAE: SCUTIGERELLA IMMACULATA NEWPORT) POPULATION GROWTH

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The suitability of selected crops and soil for garden symphylan (Scutigerella immaculata Newport) population growth was studied in the laboratory and field. In the laboratory, we measured the population increase of S. immaculata after 8 w from a starting density of 35 in pots of spinach (Spinacia o...

  5. New Patterns of American Metropolitan Population Growth in the 1970s.

    ERIC Educational Resources Information Center

    Phillips, Phillip D.

    1978-01-01

    Discusses three aspects of post-1970 American metropolitan population trends: the general dimensions of change between pre- and post-1970 population growth patterns are presented; possible causes of these changes are examined; college or high school level classroom exercises that generate awareness of recent trends and their causes are outlined.…

  6. The Future and Population: What Will a No-Growth Society Be Like? A Teaching Module.

    ERIC Educational Resources Information Center

    Population Reference Bureau, Inc., Washington, DC.

    This teaching module for high school students and adults examines the future of zero population growth in 26 countries by the year 2000. The module contains an essay for students to read, followed by exercises, activities, and discussion questions based on the essay. Objectives include understanding the components of population change, identifying…

  7. SUBLETHAL NARCOSIS AND POPULATION PERSISTENCE: A MODELING STUDY ON GROWTH EFFECTS

    EPA Science Inventory

    This study of a Daphnia population model suggests that sublethal effects of nonpolar narcotics on growth of individual organisms can result in ultimate extinction of the population at chronic chemical concentrations near the effect concentration that leads to a 50% reduction in i...

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

    PubMed

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

    2014-04-01

    The between-population genetic architecture for growth and maturation has not been examined in detail for many animal species despite its central importance in understanding hybrid fitness. We studied the genetic architecture of population divergence in: (i) maturation probabilities at the same age; (ii) size at age and growth, while accounting for maturity status and sex; and (iii) growth plasticity in response to environmental factors, using divergent wild and domesticated Atlantic salmon (Salmo salar). Our work examined two populations and their multigenerational hybrids in a common experimental arrangement in which salinity and quantity of suspended sediments were manipulated to mimic naturally occurring environmental variation. Average specific growth rates across environments differed among crosses, maturity groups, and cross-by-maturity groups, but a growth-rate reduction in the presence of suspended sediments was equal for all groups. Our results revealed both additive and nonadditive outbreeding effects for size at age and for growth rates that differed with life stage, as well as the presence of different sex- and size-specific maturation probabilities between populations. The major implication of our work is that estimates of the genetic architecture of growth and maturation can be biased if one does not simultaneously account for temporal changes in growth and for different maturation probabilities between populations. Namely, these correlated traits interact differently within each population and between sexes and among generations, due to nonadditive effects and a level of independence in the genetic control for traits. Our results emphasize the challenges to investigating and predicting phenotypic changes resulting from between-population outbreeding. PMID:24473933

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

    PubMed

    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. PMID:12158990

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

    SciTech Connect

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

    2015-10-22

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    PubMed

    Caldwell, J C; Caldwell, P

    1994-02-18

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

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

    PubMed

    Paiva, P D

    1986-01-01

    The economically active population has grown rapidly in Brazil, resulting either from population growth or increased female participation in the work force. This rhythm of growth will continue at least until the end of this century. The authors suggest that the impact of the recent decline in fertility will be moderate and will only affect the younger age groups. Despite the rapid growth of employment in the processing industry, the relative size of the so-called informal sector has remained stable since 1950. It is further predicted that, given the economically active population's rate of growth and the decrease in employment in agriculture, there will be a great demand for urban employment in the next 20 years. PMID:12143702

  14. Maximum likelihood estimation of population growth rates based on the coalescent.

    PubMed Central

    Kuhner, M K; Yamato, J; Felsenstein, J

    1998-01-01

    We describe a method for co-estimating 4Nemu (four times the product of effective population size and neutral mutation rate) and population growth rate from sequence samples using Metropolis-Hastings sampling. Population growth (or decline) is assumed to be exponential. The estimates of growth rate are biased upwards, especially when 4Nemu is low; there is also a slight upwards bias in the estimate of 4Nemu itself due to correlation between the parameters. This bias cannot be attributed solely to Metropolis-Hastings sampling but appears to be an inherent property of the estimator and is expected to appear in any approach which estimates growth rate from genealogy structure. Sampling additional unlinked loci is much more effective in reducing the bias than increasing the number or length of sequences from the same locus. PMID:9584114

  15. Population growth rate determinants for Arbacia: Evaluating ecological relevance of toxicity test endpoints

    SciTech Connect

    Nacci, D.; Gleason, T.; Munns, W.R. Jr.

    1995-12-31

    A population dynamics model for the sea urchin, Arbacia punctulata, was recently developed incorporating life stage endpoints frequently measured in acute and chronic toxicity studies. Model elasticity analysis was used to demonstrate that population growth rate was influenced most by adult survival and least by early life stage success, calling into question the ecological relevance of results from standardized Arbacia fertilization and larval development toxicity tests. Two approaches were used to continue this evaluation. Actual and hypothetical dose-response curves for toxicant exposures over multiple life stages were used to evaluate contributions to population growth rate of stage-specific toxicant effects. Additionally, relationships between critical life stages were developed from laboratory data for Arbacia. The results of this analysis underscore the importance of understanding both endpoint sensitivity to toxicants and sensitivity of population growth rate to test endpoints in determining the ecological relevance of toxicity tests results.

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    USGS Publications Warehouse

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

    2015-01-01

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

  18. Sexual Reproduction in a Simple Growth Population Model

    NASA Astrophysics Data System (ADS)

    Lemos, Carlos Gentil Oro; Santos, Marcio

    2012-05-01

    One of the most important characteristics in the survival of a species is related to the kind of reproduction responsible for the offspring generation. However, only in the last years the role played by sexual reproduction has been investigated. Then, for a better understanding of this kind of process we introduce, in this work, a surface reaction model that describes the role of the sexual reproduction. In our model two different elements of the species, representing male and female, can interact to reproduce a new element. The sex of this new element is chosen with a given probability and in order to take into account the mortality rate we introduce another kind of individual. The value of the spatial density of this element remains constant during the time evolution of the system. The model is studied using Monte Carlo simulations and mean field approximation. Depending on the values of the control parameters of the model, the system can attain two stationary states: In one of them the population survives and in the other it can be extinguished. Besides, accordingly to our results, the phase diagram of the model shows a discontinuous transition between these two states.

  19. Abrupt summer warming and changes in temperature extremes over Northeast Asia since the mid-1990s: Drivers and physical processes

    NASA Astrophysics Data System (ADS)

    Dong, Buwen; Sutton, Rowan T.; Chen, Wei; Liu, Xiaodong; Lu, Riyu; Sun, Ying

    2016-09-01

    This study investigated the drivers and physical processes for the abrupt decadal summer surface warming and increases in hot temperature extremes that occurred over Northeast Asia in the mid-1990s. Observations indicate an abrupt increase in summer mean surface air temperature (SAT) over Northeast Asia since the mid-1990s. Accompanying this abrupt surface warming, significant changes in some temperature extremes, characterized by increases in summer mean daily maximum temperature (Tmax), daily minimum temperature (Tmin), annual hottest day temperature (TXx), and annual warmest night temperature (TNx) were observed. There were also increases in the frequency of summer days (SU) and tropical nights (TR). Atmospheric general circulation model experiments forced by changes in sea surface temperature (SST)/sea ice extent (SIE), anthropogenic greenhouse gas (GHG) concentrations, and anthropogenic aerosol (AA) forcing, relative to the period 1964-93, reproduced the general patterns of observed summer mean SAT changes and associated changes in temperature extremes, although the abrupt decrease in precipitation since the mid-1990s was not simulated. Additional model experiments with different forcings indicated that changes in SST/SIE explained 76% of the area-averaged summer mean surface warming signal over Northeast Asia, while the direct impact of changes in GHG and AA explained the remaining 24% of the surface warming signal. Analysis of physical processes indicated that the direct impact of the changes in AA (through aerosol-radiation and aerosol-cloud interactions), mainly related to the reduction of AA precursor emissions over Europe, played a dominant role in the increase in TXx and a similarly important role as SST/SIE changes in the increase in the frequency of SU over Northeast Asia via AA-induced coupled atmosphere-land surface and cloud feedbacks, rather than through a direct impact of AA changes on cloud condensation nuclei. The modelling results also imply

  20. What's behind the Good News: The Decline in Teen Pregnancy Rates during the 1990s.

    ERIC Educational Resources Information Center

    Flanigan, Christine

    Noting that rates of teen pregnancies and births have declined over the past decade, this analysis examined how much of the progress is due to fewer teens having sex and how much to lower rates of pregnancy among sexually active teens. The analysis drew on data from the federal government's National Survey of Family Growth (NSFG), a large,…

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

    PubMed

    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. PMID:22851126

  2. Is Welfare Reform Responsible for Low Skilled Women's Declining Health Insurance Coverage in the 1990s?

    ERIC Educational Resources Information Center

    DeLeire, Thomas; Levine, Judith A.; Levy, Helen

    2006-01-01

    We use data from the 1989-2001 March Supplements to the Current Population Survey to determine whether welfare reform contributed to declines in health insurance coverage experienced by low-skilled women. Between 1988 and 2000, women with less than a high school education experienced an 8.0 percentage point decline in the probability of having…

  3. Canada's Schools: Report Card for the 1990s. A CEA Opinion Poll.

    ERIC Educational Resources Information Center

    Williams, Tom R.; Millinoff, Holly

    This report summarizes a poll of Canadian opinion on education. Most people gave the schools in their community a B (39 percent) or C (35 percent), suggesting a relatively high degree of satisfaction with schools. Some 29 percent of the population indicated that schools have improved over the past 4 years, 20 percent indicated they have become…

  4. Toxicology across scales: Cell population growth in vitro predicts reduced fish growth.

    PubMed

    Stadnicka-Michalak, Julita; Schirmer, Kristin; Ashauer, Roman

    2015-08-01

    Environmental risk assessment of chemicals is essential but often relies on ethically controversial and expensive methods. We show that tests using cell cultures, combined with modeling of toxicological effects, can replace tests with juvenile fish. Hundreds of thousands of fish at this developmental stage are annually used to assess the influence of chemicals on growth. Juveniles are more sensitive than adult fish, and their growth can affect their chances to survive and reproduce. Thus, to reduce the number of fish used for such tests, we propose a method that can quantitatively predict chemical impact on fish growth based on in vitro data. Our model predicts reduced fish growth in two fish species in excellent agreement with measured in vivo data of two pesticides. This promising step toward alternatives to fish toxicity testing is simple, inexpensive, and fast and only requires in vitro data for model calibration. PMID:26601229

  5. Toxicology across scales: Cell population growth in vitro predicts reduced fish growth

    PubMed Central

    Stadnicka-Michalak, Julita; Schirmer, Kristin; Ashauer, Roman

    2015-01-01

    Environmental risk assessment of chemicals is essential but often relies on ethically controversial and expensive methods. We show that tests using cell cultures, combined with modeling of toxicological effects, can replace tests with juvenile fish. Hundreds of thousands of fish at this developmental stage are annually used to assess the influence of chemicals on growth. Juveniles are more sensitive than adult fish, and their growth can affect their chances to survive and reproduce. Thus, to reduce the number of fish used for such tests, we propose a method that can quantitatively predict chemical impact on fish growth based on in vitro data. Our model predicts reduced fish growth in two fish species in excellent agreement with measured in vivo data of two pesticides. This promising step toward alternatives to fish toxicity testing is simple, inexpensive, and fast and only requires in vitro data for model calibration. PMID:26601229

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

    PubMed

    Barnabas, A P

    1974-01-01

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

  7. The Commission on Population Growth and the American Future: its origins, operations, and aftermath.

    PubMed

    Westoff, C F

    1973-10-01

    The origins, organization, and operation of the Commission on Population Growth and the American Future and the response to its report are described. The origins of the Commission are traced to a concern with the consequences of U.S. population growth on the part of such key individuals as John D. Rockefeller 3rd and Paul Ehrlich. Because the Commission was a statutory creation of Congress, its membership included 4 Congressmen in addition to 20 distinguished citizens representing a spectrum of groups and views. The evaluation of the consequences of growth, as opposed to the means of reducing fertility, became the major concern of the research effort. Several issues led to differences within the Commission: 1) A narrow versus a broad definition of the scope of the report; 2) differing perceptions of the population problem as manifested by the ecological view, the "unwanted fertility" school, and the social justice view. The social science work contracted by the Commission had a significant impact on the final report's substance: 1) the demographic work on population projections was crucial to the analysis of the consequences of growth; 2) evaluating the demographic capability of national "growth center strategy" had an influence; and 3) the need to eliminate unwanted fertility was confirmed as a necessary priority. The basic thrust of the Commission's report was to recomment slowing growth in order to maximize the quality of life. PMID:12257905

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Slow Protein Fluctuations Explain the Emergence of Growth Phenotypes and Persistence in Clonal Bacterial Populations

    PubMed Central

    Rocco, Andrea; Kierzek, Andrzej M.; McFadden, Johnjoe

    2013-01-01

    One of the most challenging problems in microbiology is to understand how a small fraction of microbes that resists killing by antibiotics can emerge in a population of genetically identical cells, the phenomenon known as persistence or drug tolerance. Its characteristic signature is the biphasic kill curve, whereby microbes exposed to a bactericidal agent are initially killed very rapidly but then much more slowly. Here we relate this problem to the more general problem of understanding the emergence of distinct growth phenotypes in clonal populations. We address the problem mathematically by adopting the framework of the phenomenon of so-called weak ergodicity breaking, well known in dynamical physical systems, which we extend to the biological context. We show analytically and by direct stochastic simulations that distinct growth phenotypes can emerge as a consequence of slow-down of stochastic fluctuations in the expression of a gene controlling growth rate. In the regime of fast gene transcription, the system is ergodic, the growth rate distribution is unimodal, and accounts for one phenotype only. In contrast, at slow transcription and fast translation, weakly non-ergodic components emerge, the population distribution of growth rates becomes bimodal, and two distinct growth phenotypes are identified. When coupled to the well-established growth rate dependence of antibiotic killing, this model describes the observed fast and slow killing phases, and reproduces much of the phenomenology of bacterial persistence. The model has major implications for efforts to develop control strategies for persistent infections. PMID:23382887

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

    PubMed Central

    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

  11. Dynamic-analogue correction of the decadal change of East Asian summer precipitation in the late 1990s

    NASA Astrophysics Data System (ADS)

    Gong, Zhiqiang; Li, Shangfeng; Hu, Po; Shen, Baizhu; Feng, Guolin

    2016-06-01

    This paper systematically evaluates the deviations that appear in the hindcasts of the East Asian summer precipitation (EASP) decadal change in the late 1990s in two global coupled models (BCC_CGCM and BCC_CSM). The possible causes for the deviations between the model hindcasts and observations are analyzed. The results show that the hindcasts of EASP by BCC_CGCM and BCC_CSM deviate from observations, with the anomaly correlation coefficient (ACC) being -0.01 and -0.09 for the two models, respectively. The SST anomalies in North and West Pacific and the SST index values predicted by the two models also deviate from the observations, indicating that inconsistent SST fields may be the key factor leading to the deviation in the prediction of the EASP decadal shift. Thus, a dynamic-analogue scheme is proposed to correct the precipitation hindcasts by using SSTs, where SST and EASP are highly correlated, to select historical analogue cases. Cross validations show that the average ACC of the temporal-latitude distribution of the EASP between the corrected hindcasts and observations is 0.18 for BCC_CGCM and 0.02 for BCC_CSM; both are much higher than the uncorrected hindcasts. Applying the dynamic-analogue correction scheme in both models successfully improves prediction of the EASP decadal change in the late 1990s.

  12. Nature of Persecutors and Their Behaviors in the Delusions of Schizophrenia: Changes between the 1990s and the 2000s

    PubMed Central

    Oh, Hyun Young; Kim, Daeho

    2012-01-01

    Objective Research suggests that the contents of delusions in schizophrenia are influenced by culture and social environment. However, few studies have investigated the chronological change of such delusions within a society. To investigate specifically the changes in the persecutory delusions of schizophrenia that have occurred over time, we compared the nature of the persecutors and their persecutory behaviors among inpatients with schizophrenia. Methods All admissions to the psychiatric unit of Hanyang University Guri Hospital with discharge diagnoses of schizophrenia during two different five-year time frames (1996-2000 and 2006-2010) were reviewed. From their inpatient medical records, we investigated the descriptions of persecutors and their persecutory behaviors in the delusions of 124 patients (54 in the1990s and 72 in the 2000s). Results Overall, persecutory behaviors and nature of persecutors in the delusions of schizophrenia did not differ between the two time frames. However, subgroup analysis revealed that in women but not in men, rejection as a persecutory behavior was significantly higher in the 1990s (p<0.05). Conclusion The ten-year time interval may be too short to find significant changes in delusional content in general. However, our additional finding in women may be a result of the tremendous change in status of Korean women during the last decade. PMID:23251194

  13. The presence of Bt-transgenic oilseed rape in wild mustard populations affects plant growth.

    PubMed

    Liu, Yongbo; Stewart, C Neal; Li, Junsheng; Huang, Hai; Zhang, Xitao

    2015-12-01

    The adventitious presence of transgenic plants in wild plant populations is of ecological and regulatory concern, but the consequences of adventitious presence are not well understood. Here, we introduced Bacillus thuringiensis Cry1Ac (Bt)-transgenic oilseed rape (Bt OSR, Brassica napus) with various frequencies into wild mustard (Brassica juncea) populations. We sought to better understand the adventitious presence of this transgenic insecticidal crop in a wild-relative plant population. We assessed the factors of competition, resource availability and diamondback moth (Plutella xylostella) infestation on plant population dynamics. As expected, Bt OSR performed better than wild mustard in mixed populations under herbivore attack in habitats with enough resources, whereas wild mustard had higher fitness when Bt OSR was rarer in habitats with limited resources. Results suggest that the presence of insect-resistant transgenic plants could decrease the growth of wild mustard and Bt OSR plants and their populations, especially under high herbivore pressure. PMID:26338267

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated the effects of temperature and relative humidity on population growth and development of the psocid Liposcelis brunnea Motschulsky. L. brunnea did not survive at 43% RH, while populations increased from 22.5-32.5°C and 55 -75% RH. Interestingly, we found L. brunnea population growth ...

  17. Isonicotinic acid hydrazide inhibits cell population growth during teratogenesis of chick embryo.

    PubMed

    Joshi, M V; Shah, V B; Modak, S P

    1991-01-01

    In chick embryos treated with a 4 hr pulse of 7.2 X 10(-5) M isonicotinic acid hydrazide (INH) the cell population growth is inhibited with an increased population doubling time. Teratogenised blastoderm cells complete their ongoing cell cycle and arrest in G1 phase. A chase with an equimolar concentration of pyridoxal-5-phosphate restores the growth rate after a lag of 4 hr equivalent to the duration of treatment with INH. Presumptive mesoblast cells invaginated through the primitive streak and neuroectoblast cells induced prior to the application of INH differentiate, while the teratogen inhibits morphogenesis and organization of organ primordia. PMID:1864614

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

    ERIC Educational Resources Information Center

    Mahar, Dennis J., Ed.; And Others

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

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

    PubMed Central

    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 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. PMID:24163615

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

    USGS Publications Warehouse

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

    2003-01-01

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

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

    USGS Publications Warehouse

    Hansen, Michael J.; Nate, Nancy A.

    2014-01-01

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

  2. Multigenerational effect of perfluorooctane sulfonate (PFOS) on the individual fitness and population growth of Daphnia magna.

    PubMed

    Jeong, Tae-Yong; Yuk, Min-Su; Jeon, Junho; Kim, Sang Don

    2016-11-01

    We investigated the multigenerational effect of PFOS to individual fitness (e.g., body weight, acetylcholinesterase and glutathione S-transferase) and population growth (e.g., offspring number and time to first brood) of Daphnia magna during continuous and discontinuous exposures. The intrinsic rate of population growth was also calculated. In the continuous exposure, population growth-related adverse effects were detected during all test periods, and the adverse effect tended to be weaker in later generations. On the other hand, individual fitness-related adverse effects were observed from F1 not in F0 and deteriorated as the generation number increased. These results imply that individual fitness worsens although the population growth is restored in later generations. Upon discontinuous exposure, a few but significant adverse effects were observed during the non-exposure period and highest effects were detected during the re-exposure period. This encourages the study of different exposure scenarios, which may result in unexpected and higher PFOS toxicity. Consequently, this study confirms adverse effects of PFOS to Daphnia magna in multigenerational period and supports reasons for studies linking individual fitness changes to population dynamics and covering diverse exposure scenarios to evaluate the risk of PFOS in a water environment. PMID:27396314

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

    NASA Astrophysics Data System (ADS)

    Hüsler, A. D.; Sornette, D.

    2014-10-01

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

  4. Existence of Limit Cycles in the Solow Model with Delayed-Logistic Population Growth

    PubMed Central

    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. PMID:24592147

  5. Dynamics of individual growth in a recovering population of lake trout (Salvelinus namaycush)

    USGS Publications Warehouse

    Fabrizio, Mary C.; Dorazio, Robert M.; Schram, Stephen T.

    2001-01-01

    In 1976, the Wisconsin Department of Natural Resources established a refuge for a nearly depleted population of lake trout (Salvelinus namaycush) at Gull Island Shoal, Lake Superior. The refuge was intended to reduce fishing mortality by protecting adult lake trout. We examined the growth dynamics of these lake trout during the period of recovery by comparing estimates of ndividual growth before and after the refuge was established. Our estimates are based on an annual mark-recapture survey conducted at the spawning area since 1969. We developed a model that allowed mean growth rates to differ among individuals of different sizes and that accommodated variation in growth rates of individuals of the same size. Likelihood ratio tests were used to determine if the mean growth increments of lake trout changed ater the refuge was established. Our results suggest that growth of mature lake trout (particularly wild fish) decreased significantly in the postrefuge period. This decreased growth may have been associated with a reduction in food availability. We also observed reductions in growth as wild fish grew older and larger, which suggests that the growth of these fish may be adequately approximated by a von Bertalanffy growth model if it becomes possible to obtain accurate ages.

  6. Comparison of native and introduced flathead catfish populations in Alabama and Georgia: Growth, mortality, and management

    USGS Publications Warehouse

    Sakaris, P.C.; Irwin, E.R.; Jolley, J.C.; Harrison, D.

    2006-01-01

    We compared growth of flathead catfish Pylodictis olivaris from two native populations in Alabama (Coosa and Tallapoosa rivers) and two introduced populations in Georgia (Ocmulgee and Satilla rivers). We also compared mortality rates and potential outcomes of various management regimes (minimum length limits [MLLs]) among the populations. Total length-log10(age) regression slopes for introduced fish were higher than those for native fish, and von Bertalanffy growth coefficients (K) were greater for introduced fish (Ocmulgee: 0.195; Satilla: 0.201) than for native individuals (Coosa: 0.057; Tallapoosa: 0.059). Therefore, introduced flathead catfish grew more rapidly than those in their native range. Mortality (instantaneous mortality rate, Z) was higher in the Satilla River population (Z = -0.602) than in the Ocmulgee River (Z = -0.227) and Coosa River (Z = -0.156) populations. However, fish in the Satilla River population had been introduced for only 10 years and presumably did not reach their theoretical maximum age, potentially biasing the mortality estimate for that population. Simulation of management regimes in Fishery Analyses and Simulation Tools software predicted that maximum biomass of flathead catfish in the Ocmulgee (1,668 kg) and Satilla (1,137 kg) rivers was substantially larger than that in the Coosa (873 kg) and Tallapoosa (768 kg) populations. However, increased exploitation rates in the Ocmulgee and Satilla River populations resulted in dramatic declines in overall biomass, especially at lower MLLs (254 and 356 mm, respectively). Therefore, in systems where introduced flathead catfish represent an important recreational fishery but have dramatically reduced the abundance of native fishes through predation, minimal protection is recommended. We contend that rapid growth of introduced flathead catfish has major implications for their management and the conservation of native fishes. ?? Copyright by the American Fisheries Society 2006.

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

    PubMed

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

    2015-01-01

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

  8. Networking of networks: a 1990s approach to information for development.

    PubMed

    1992-06-01

    The ability to access and use information is increasingly becoming a crucial determinant of a country's ability to achieve sustainable socioeconomic development. Countries which are able to manage and utilize data and information have a competitive advantage over other nations. Countries which fail to tap into the growing global knowledge base, develop a complementary local knowledge base, promote the dissemination and use of knowledge, and invest in institutional and technical human capital will, however, simply remain or fall behind the competition. Many developing countries lack appropriate strategy, financial support for information centers and networks, timely adoption and use of new technology, adequate telecommunications infrastructure, and coordination at national and regional levels. Further, telecommunications services are costly, research on user group behavior is inadequate, few technically skilled people are available, and governments fail to recognize the importance of joining international information networks. Policy development, maternal-child health and family planning, and information, education, and communication are 3 of the most significant population issues worldwide. To best address these issues, international development agencies are urged to veer from providing capital and to directly support greater access to information and enhanced knowledge leading to sustainable national development. Thus far the UN has helped create global information systems in certain areas, and regional cooperative information systems are being developed. ESCAP has taken the lead in Asia and the Pacific. Gradually, population libraries and information centers are becoming computerized. Greater effort is recommended to recover costs for services and products. Further, donors and country organizations should stress that information is only useful as far as it is used. PMID:12317835

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

    USGS Publications Warehouse

    Mech, L. David; Fieberg, John

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Liu, Xue-Mei; Li, Zhi-Bing; Xie, Hui-Zhang; Ai, Bao-Quan; Cheng, Xiao-Bo; Liu, Liang-Gang

    2007-07-01

    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 μ and its fluctuation also affect the steady probability distribution and can push it toward a small population.

  11. Population dynamics of bowfin in a south Georgia reservoir: latitudinal comparisons of population structure, growth, and mortality

    USGS Publications Warehouse

    Porter, Nicholas J.; Bonvechio, Timothy F.; McCormick, Joshua L.; Quist, Michael

    2014-01-01

    The objectives of this study were to evaluate the population dynamics of bowfin (Amia calva) in Lake Lindsay Grace, Georgia, and to compare those dynamics to other bowfin populations. Relative abundance of bowfin sampled in 2010 in Lake Lindsay Grace was low and variable (mean±SD; 2.7±4.7 fish per hour of electrofishing). Total length (TL) of bowfin collected in Lake Lindsay Grace varied from 233–683 mm. Age of bowfin in Lake Lindsay Grace varied from 0–5 yr. Total annual mortality (A) was estimated at 68%. Both sexes appeared to be fully mature by age 2 with gonadosomatic index values above 8 for females and close to 1 for males. The majority of females were older, longer, and heavier than males. Bowfin in Lake Lindsay Grace had fast growth up to age 4 and higher total annual mortality than the other populations examined in this study. A chi-square test indicated that size structure of bowfin from Lake Lindsay Grace was different than those of a Louisiana population and two bowfin populations from the upper Mississippi River. To further assess bowfin size structure, we proposed standard length (i.e., TL) categories: stock (200 mm, 8 inches), quality (350 mm, 14 inches), preferred (460 mm, 18 inches), memorable (560 mm, 22, inches), and trophy (710 mm, 28 inches). Because our knowledge of bowfin ecology is limited, additional understanding of bowfin population dynamics provides important insight that can be used in management of bowfin across their distribution.

  12. Understanding the rapid summer warming and changes in temperature extremes since the mid-1990s over Western Europe

    NASA Astrophysics Data System (ADS)

    Dong, Buwen; Sutton, Rowan T.; Shaffrey, Len

    2016-05-01

    Analysis of observations indicates that there was a rapid increase in summer (June-August) mean surface air temperature (SAT) since the mid-1990s over Western Europe. Accompanying this rapid warming are significant increases in summer mean daily maximum temperature, daily minimum temperature, annual hottest day temperature and warmest night temperature, and an increase in frequency of summer days and tropical nights, while the change in the diurnal temperature range (DTR) is small. This study focuses on understanding causes of the rapid summer warming and associated temperature extreme changes. A set of experiments using the atmospheric component of the state-of-the-art HadGEM3 global climate model have been carried out to quantify relative roles of changes in sea surface temperature (SST)/sea ice extent (SIE), anthropogenic greenhouse gases (GHGs), and anthropogenic aerosols (AAer). Results indicate that the model forced by changes in all forcings reproduces many of the observed changes since the mid-1990s over Western Europe. Changes in SST/SIE explain 62.2 ± 13.0 % of the area averaged seasonal mean warming signal over Western Europe, with the remaining 37.8 ± 13.6 % of the warming explained by the direct impact of changes in GHGs and AAer. Results further indicate that the direct impact of the reduction of AAer precursor emissions over Europe, mainly through aerosol-radiation interaction with additional contributions from aerosol-cloud interaction and coupled atmosphere-land surface feedbacks, is a key factor for increases in annual hottest day temperature and in frequency of summer days. It explains 45.5 ± 17.6 % and 40.9 ± 18.4 % of area averaged signals for these temperature extremes. The direct impact of the reduction of AAer precursor emissions over Europe acts to increase DTR locally, but the change in DTR is countered by the direct impact of GHGs forcing. In the next few decades, greenhouse gas concentrations will continue to rise and AAer precursor

  13. The control of population growth is the function of the central government.

    PubMed

    1994-04-01

    This speech of Mr. Jiang Zemin, General Secretary of the Central Committee of the Chinese Communist Party and Chairman of the People's Republic of China, before the National Forum on Family Planning Work refers to the need to strictly and effectively implement the family planning program in 1994. Socioeconomic reforms will be occurring simultaneously. Success of the family planning program is attributed to Party Committees, governments, cadres, and the masses. Even though there have been advances made in slowing population growth, the vast size of the Chinese population still poses problems. China's state policy is to modernize and to maintain strict control of overrapid population growth. The strategy is to move toward a market economy, while continuing to slow population growth but without market regulation of population growth. Family planning serves the state and the people through voluntary action. The public must receive "meticulous" education and help with day to day problems in production, daily life, and human reproduction. Government departments and nongovernmental organizations need to work together. Family planning use is the obligation of every citizen, who should be made aware of relevant national policy and of the need for devotion to country. Benefits will be received by the state and families, when family planning is used. Family planning will be cultivated as an honorable act, and boys and girls will be valued equally. The educational program will train leaders and cadres to take a leadership role in practicing family planning. Party organizations and governments at all levels should take personal responsibility for program implementation. Erratic efforts are not good enough; the task is long and arduous. Serious difficulties still exist in rural areas, and program focus should be directed to rural areas and the floating population. Reports were also made at the Forum on the population status and preparatory meetings of the forthcoming women

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

    ERIC Educational Resources Information Center

    McNicoll, Geoffrey

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

  15. Recovering population parameters from a single gene genealogy: an unbiased estimator of the growth rate.

    PubMed

    Maruvka, Yosef E; Shnerb, Nadav M; Bar-Yam, Yaneer; Wakeley, John

    2011-05-01

    We show that the number of lineages ancestral to a sample, as a function of time back into the past, which we call the number of lineages as a function of time (NLFT), is a nearly deterministic property of large-sample gene genealogies. We obtain analytic expressions for the NLFT for both constant-sized and exponentially growing populations. The low level of stochastic variation associated with the NLFT of a large sample suggests using the NLFT to make estimates of population parameters. Based on this, we develop a new computational method of inferring the size and growth rate of a population from a large sample of DNA sequences at a single locus. We apply our method first to a sample of 1,212 mitochondrial DNA (mtDNA) sequences from China, confirming a pattern of recent population growth previously identified using other techniques, but with much smaller confidence intervals for past population sizes due to the low variation of the NLFT. We further analyze a set of 63 mtDNA sequences from blue whales (BWs), concluding that the population grew in the past. This calls for reevaluation of previous studies that were based on the assumption that the BW population was fixed. PMID:21172828

  16. Biopharmaceutical Innovation System in China: System Evolution and Policy Transitions (Pre-1990s-2010s)

    PubMed Central

    Hu, Hao; Chung, Chao-Chen

    2015-01-01

    Background: This article sets up the initial discussion of the evolution of biopharmaceutical innovation in China through the perspective of sectoral innovation system (SIS). Methods: Two data sources including archival documentary data and field interviews were used in this study. Archival documentary data was collected from China Food and Drug Administration (CFDA) and Chinese National Knowledge Infrastructure (CNKI). In addition, industrial practitioners and leading researchers in academia were interviewed. Results: Biopharmaceutical in China was established through international knowledge transfer. The firms played more active role in commercializing biopharmaceutical in China though universities and research institutes were starting to interact with local firms and make contribution to biopharmaceutical industrialization. The transition of the Chinese government’s policies continuously shapes the evolution of biopharmaceutical sector. Policies have been dramatic changes before and after 1980s to encourage developing biopharmaceutical as a competitive industry for China. Conclusion: A SIS for biopharmaceutical has been shaped in China. However, currently biopharmaceutical is still a small sector in China, and for the further growth of the industry more synthetic policies should be implemented. Not only the policy supports towards the research and innovation of biopharmaceuticals in the early stage of development should be attended, but also commercialization of biopharmaceutical products in the later stage of sales. PMID:26673466

  17. Health promotion practice and public health: challenge for the 1990s. Heart Health Think Tank Group.

    PubMed

    Hall, N; Best, J A

    1997-01-01

    The issue of practice skills arose in the course of a process evaluation of the Heart Smart North Shore (HSNS) project in British Columbia. We created a Think Tank of researchers and community practitioners to make recommendations for improvement of our skills. These recommendations differed according to different values for health and opinions on how to create health in the community. Because the site reviewers of the HSNS project were clear this was a disease prevention project and not a community development initiative, HSNS's orientation to skill development after the Think Tank moved toward the Precede/Proceed model, the Transtheoretical model and social marketing approaches. The Health Unit has now been restructured into multidisciplinary service teams which must focus on population health, evidence-based practice and the social determinants of health, and thus need to consider health promotion from a community development perspective and empowerment model. We suggest that learning and the development of staff and community volunteers should be seen as a continuous and reflective process that takes place at the individual, community and organizational level. PMID:9458570

  18. Palliative care by family physicians in the 1990s. Resilience amid reform.

    PubMed Central

    Burge, F.; McIntyre, P.; Twohig, P.; Cummings, I.; Kaufman, D.; Frager, G.; Pollett, A.

    2001-01-01

    OBJECTIVE: To explore issues family physicians face in providing community-based palliative care to their patients in the context of a changing health care system. DESIGN: Focus groups. SETTING: Small (< 10,000 population), medium-sized (10,000 to 50,000), and large (> 50,000) communities in Nova Scotia. PARTICIPANTS: Twenty-five men and women physicians with varying years of practice experience in both solo and group practices. METHOD: A semistructured approach was used, asking physicians to reflect on recent palliative care experiences in order to explore issues of care. MAIN FINDINGS: Five themes emerged from the discussions: resources needed, availability of family support, time and money supporting physicians' activities, symptom control for patients, and physicians' emotional reactions to caring for dying patients. CONCLUSION: With downsizing of hospitals and greater emphasis on community-based care, the issues identified in this study will need attention, particularly in designing an integrated service delivery model for palliative care. PMID:11723593

  19. Metal concentrations in Maryland`s shellfish: 1970s--1990s

    SciTech Connect

    Murphy, D.L.

    1995-12-31

    Maryland has been monitoring arsenic, cadmium, chromium, copper, lead, mercury and zinc in bivalve shellfish from state waters since the 1960s. The primary bivalve species monitored in Maryland waters are the oyster, Crassostrea virginica and the softshell clam, Mya arenaria. These data have been evaluated for temporal trends. In order to insure that temporal evaluations be based upon data produced using comparable analytical methods, the time period evaluated is not the same for all analytes. For example, while most evaluations are for the period 1974 through 1994, arsenic data were evaluated for the period 1980 through 1994. Data for oyster tissue indicate declines in levels of mercury, cadmium, arsenic, copper and zinc on the order of 70--90%. The major portion of these reductions occurred prior to 1985. These declines are evident from data collected from Maryland`s lower eastern shore, a relatively remote area, as well as from waters closer to larger population centers. Past detection levels for lead and chromium were insufficiently low to detect temporal changes.

  20. Integrated kinetic and probabilistic modeling of the growth potential of bacterial populations.

    PubMed

    George, S M; Métris, A; Baranyi, J

    2015-05-01

    When bacteria are exposed to osmotic stress, some cells recover and grow, while others die or are unculturable. This leads to a viable count growth curve where the cell number decreases before the onset of the exponential growth phase. From such curves, it is impossible to estimate what proportion of the initial cells generates the growth because it leads to an ill-conditioned numerical problem. Here, we applied a combination of experimental and statistical methods, based on optical density measurements, to infer both the probability of growth and the maximum specific growth rate of the culture. We quantified the growth potential of a bacterial population as a quantity composed from the probability of growth and the "suitability" of the growing subpopulation to the new environment. We found that, for all three laboratory media studied, the probability of growth decreased while the "work to be done" by the growing subpopulation (defined as the negative logarithm of their suitability parameter) increased with NaCl concentration. The results suggest that the effect of medium on the probability of growth could be described by a simple shift parameter, a differential NaCl concentration that can be accounted for by the change in the medium composition. Finally, we highlighted the need for further understanding of the effect of the osmoprotectant glycine betaine on metabolism. PMID:25747002

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

    EPA Science Inventory

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

  2. Rapid Population Growth and Rural Community Change: A Focus on Land Use Issues.

    ERIC Educational Resources Information Center

    Garkovich, Lorraine

    Land use controls are often a major point of conflict between recent migrants and long-term residents of rapidly growing communities. Such conflict was noted in a case study of a rural community undergoing rapid population growth. The revision of a comprehensive land use plan for the community provided the opportunity to evaluate citizen…

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

    ERIC Educational Resources Information Center

    Ninbet, Steven; Hurley, Gabrielle; Weldon, Elizabeth

    2006-01-01

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

  4. Population growth and development of the psocid Lepinotus reticulatus at constant temperatures and relative humidities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated the effects of temperature and relative humidity on population growth and development of the psocid Lepinotus reticulatus Enderlein. Part of this study assessed the effects of marking psocids using methylene blue, chalk powder, and fluorescent powder to differentiate nymphal stages d...

  5. The Effect of Population Growth upon the Quantity of Education Children Receive.

    ERIC Educational Resources Information Center

    Simon, Julian L.; Pilarski, Adam M.

    1979-01-01

    There is indeed some negative effect of population growth on the amount of education in developing nations, but the effect is less severe than has been thought. This finding is in sharp contrast to previous conclusions drawn from similar cross-national data. Available from Review of Economics and Statistics, M-8 Littauer Center, Cambridge, MA…

  6. Population Growth. Understanding Global Change: Earth Science and Human Impacts. Global Change Instruction Program.

    ERIC Educational Resources Information Center

    Jacobsen, Judith E.

    The Global Change Instruction Program was designed by college professors to fill a need for interdisciplinary materials on the emerging science of global change. This instructional module concentrates on interactions between population growth and human activities that produce global change. The materials are designed for undergraduate students…

  7. Validity of Personal Growth Initiative Scale Scores with a Mexican American College Student Population

    ERIC Educational Resources Information Center

    Robitschek, Christine

    2003-01-01

    This study tested the validity of scores on the Personal Growth Initiative Scale (PGIS; C. Robitschek, 1998, 1999) with a Mexican American college student sample. Results indicated that the PGIS scores appear to be culturally relevant for this population, with scores on the PGIS having many similar relations with other variables that have been…

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

    ERIC Educational Resources Information Center

    Wallace, Robert L.

    2005-01-01

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

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

    PubMed Central

    Stutz, Aaron Jonas

    2014-01-01

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

  10. Potential effects of environmental contamination on Yuma Myotis demography and population growth.

    PubMed

    Frick, Winifred F; Rainey, William E; Pierson, Elizabeth D

    2007-06-01

    Unplanned natural and anthropogenic disasters provide unique opportunities for investigating the influence of perturbations on population vital rates and species recovery times. We investigated the potential effects of a major pesticide spill by comparing annual survival rates using mark-recapture techniques on a riparian bat species, Yuma Myotis (Myotis yumanensis). Demography and population dynamics for most bat species remain poorly understood despite advances in mark-recapture estimation and modeling techniques. We compared survival and population growth rates of two roost populations exposed to a large chemical (metam sodium) spill in the upper Sacramento River in Northern California with two roost populations outside the contaminated area from 1992 to 1996. Hypotheses about long-term effects of the spill on female juvenile and adult survival were tested using an information-theoretic approach (AIC). Working hypotheses included effects of age, chemical spill, and time trend on survival. Female adult survival was higher than female juvenile survival across all sites, suggesting stage-specific mortality risks. Model-averaged estimates of female juvenile survival in the contaminated area (0.50-0.74) were lower than in control roosts (0.60-0.78) for each year in the study, suggesting that the spill may have reduced juvenile survival for several years. Female adult survival (0.73-0.89) did not appear to be strongly affected by the spill during the years of the study. There was an increase in survival for both stage-classes across all populations during the study period, which may have been caused by the end of an extended drought in California in the winter of 1993. The spill-affected population was in decline for the first year of the study as indicated by an estimated growth rate (lambda) < 1, but population growth rates increased during the four-year period. PMID:17555229

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

    PubMed

    Howat, Peter; Stoneham, Melissa

    2011-12-01

    Australia's population could reach 42 million by 2050. This rapid population growth, if unabated, will have significant social, public health and environmental implications. On the one hand, it is a major driver of climate change and environmental degradation; on the other it is likely to be a major contributor to growing social and health issues including a decline in quality of life for many residents. Disadvantaged and vulnerable groups will be most affected. The environmental, social and health-related issues include: pressure on the limited arable land in Australia; increased volumes of industrial and domestic waste; inadequate essential services; traffic congestion; lack of affordable housing; declining mental health; increased obesity problems; and inadequate aged care services. Many of these factors are related to the aggravation of climate change and health inequities. It is critical that the Australian Government develops a sustainable population plan with stabilisation of population growth as an option. The plan needs to ensure adequate hospitals and healthcare services, education facilities, road infrastructure, sustainable transport options, water quality and quantity, utilities and other amenities that are already severely overburdened in Australian cities. There is a need for a guarantee that affordable housing will be available and priority be given to training young people and Indigenous people for employment. This paper presents evidence to support the need for the stabilisation of population growth as one of the most significant measures to control climate change as well as to improve public health equity. PMID:22518917

  12. Disappearance of the southeast U.S. "warming hole" with the late 1990s transition of the Interdecadal Pacific Oscillation

    NASA Astrophysics Data System (ADS)

    Meehl, Gerald A.; Arblaster, Julie M.; Chung, Christine T. Y.

    2015-07-01

    Observed surface air temperatures over the contiguous U.S. for the second half of the twentieth century showed a slight cooling over the southeastern part of the country, the so-called "warming hole," while temperatures over the rest of the country warmed. This pattern reversed after 2000. Climate model simulations show that the disappearance of the warming hole in the early 2000s is likely associated with the transition of the Interdecadal Pacific Oscillation (IPO) phase from positive to negative in the tropical Pacific in the late 1990s, coincident with the early 2000s slowdown of the warming trend in globally averaged surface air temperature. Analysis of a specified convective heating anomaly sensitivity experiment in an atmosphere-only model traces the disappearance of the warming hole to negative sea surface temperature anomalies and consequent negative precipitation and convective heating anomalies in the central equatorial Pacific Ocean associated with the negative phase of the IPO after 2000.

  13. Expectations and beliefs in science communication: Learning from three European gene therapy discussions of the early 1990s.

    PubMed

    Meyer, Gitte

    2016-04-01

    There is widespread agreement that the potential of gene therapy was oversold in the early 1990s. This study, however, comparing written material from the British, Danish and German gene therapy discourses of the period finds significant differences: Over-optimism was not equally strong everywhere; gene therapy was not universally hyped. Against that background, attention is directed towards another area of variation in the material: different basic assumptions about science and scientists. Exploring such culturally rooted assumptions and beliefs and their possible significance to science communication practices, it is argued that deep beliefs may constitute drivers of hype that are particularly difficult to deal with. To participants in science communication, the discouragement of hype, viewed as a practical-ethical challenge, can be seen as a learning exercise that includes critical attention to internalised beliefs. PMID:25313143

  14. Environmental monitoring report for commercial low-level radioactive waste disposal sites (1960`s through 1990`s)

    SciTech Connect

    1996-11-01

    During the time period covered in this report (1960`s through early 1990`s), six commercial low-level radioactive waste (LLRW) disposal facilities have been operated in the US. This report provides environmental monitoring data collected at each site. The report summarizes: (1) each site`s general design, (2) each site`s inventory, (3) the environmental monitoring program for each site and the data obtained as the program has evolved, and (4) what the program has indicated about releases to off-site areas, if any, including a statement of the actual health and safety significance of any release. A summary with conclusions is provided at the end of each site`s chapter. The six commercial LLRW disposal sites discussed are located near: Sheffield, Illinois; Maxey Flats, Kentucky; Beatty, Nevada; West Valley, New York; Barnwell, South Carolina; Richland, Washington.

  15. CEO expectation: the Star Wars materiel manager of the 1990s, or C-3PO as role model.

    PubMed

    Zenty, T F; Olson, M R

    1993-05-01

    Materiel-intensive expenditures account for a significant portion of all hospital costs, second only to salaries and wages, yet materiel managers may often be overlooked as key members of the management team. This is alarming since the potential exists for materiel managers to impact annual savings of hundreds of thousands of dollars by operating efficient departments. Materiel managers have a tremendous opportunity to enhance their image and improve hospital productivity in the coming decade. The challenges of the 1990s will stretch materiel managers' skills toward enhancing their professionalism and achieving the expectations of themselves and top management. If materiel managers will effectively utilize (C3)PO they will increase their educational levels, continue to learn new skills, maintain a customer-oriented management style, exercise creativity, develop and adhere to standards, and be proactive in their responsibilities. The benefits of their success will be felt by patients, hospitals, the industry, and materiel managers everywhere. PMID:10125274

  16. The effect of competition on reserve capacity: The case of California hospitals in the late 1990s.

    PubMed

    Santerre, Rexford E; Adams, Ammon S

    2002-09-01

    This paper empirically investigates how competitive forces have affected bed capacity in the California hospital services industry using a data set for the late 1990s. The empirical results offer several conclusions about the effect of different types of competition on bed capacity during a period characterized by heightened price consciousness. In contrast to earlier periods, hospitals are found to continuously react to increased inter-hospital competition by reducing the supply of beds relative to patient demand. Similar to earlier periods, the empirical results suggest that increased physician/supplier competition leads to a reduction in bed capacity. Finally and in contrast to earlier studies, findings indicate that increased payer competition, as measured by the percentage of managed care patients in the market area, causes less bed capacity up to a point. PMID:14625941

  17. When 'drugs' become 'drugs': issues of pharmaceutical abuse in France from the 1960s to the 1990s.

    PubMed

    Marchant, Alexandre

    2014-01-01

    Since the 1970s, media frenzies about drug addiction have focused mainly on illicit drugs taken by rebellious or marginalised addicts, relegating iatrogenic drug abuse, and policies and problems linked to psychotropic pharmaceuticals available by prescription or over-the-counter to the shadows. In this article I go beyond the division between illicit drugs and medicines still configuring both public representations and historiography: using archival materials from the 1960s-1990s in France, I highlight some blind spots in drug history. Firstly I demonstrate the role of pharmaceutical abuse in the career of addicts, and then examine regulation policies, which are the dark side, however complementary, of drug policies and prohibition. Finally, I analyse the role of physicians and pharmacists in this control, and discuss the various professional debates relating to the legal supply of psychoactive drugs. In all these issues, the frame of the Cold War context will also be highlighted. PMID:26054215

  18. Causes of the Decline in Cigarette Smoking Among African American Youths From the 1970s to the 1990s

    PubMed Central

    Foulds, Jonathan

    2011-01-01

    Adult cigarette smoking prevalence trends among African Americans (AAs) and Whites are similar. However, during the decline in youth smoking that occurred between the mid-1970s and the early 1990s, the drop in smoking rates among AA adolescents was more than double that among Whites. We examined the evidence for potential explanations for this phenomenon. On the basis of our findings, we propose that racial differences in parental attitudes, religious ties, negative perceptions and experiences of the health effects of smoking, worsening poverty, increased use of food stamps, and price sensitivity were major factors contributing to the more rapid decrease in and continued lower rates of smoking among AA youths. PMID:21852655

  19. Eosinophils in the 1990s: new perspectives on their role in health and disease.

    PubMed Central

    Wardlaw, A. J.

    1994-01-01

    Eosinophils are characterized by their unique crystalloid granules that contain four basic proteins--MBP, ECP, EDN and EPO. The cell has many common features with neutrophils but, unlike that cell type, eosinophils utilize VLA-4/VCAM-1 as an adherence pathway and have a number of other receptors not shared by neutrophils. These include recognition units for IgE (distinct from CD23), and receptors for IL-5, IL-3 and RANTES. Following stimulation with a variety of agents, eosinophils preferentially elaborate LTC4 as the major 5-lipoxygenase product of arachidonic acid and produce substantial amounts of PAF. Of particular interest is the ability of eosinophils to synthesize a number of cytokines. Thus eosinophils have marked pro-inflammatory potential. There is now convincing evidence that eosinophilia is T-cell dependent. The Th2-type cell, which selectively secretes IL-5 and IL-4, seems particularly involved. IL-5, IL-3 and GM-CSF are required for eosinophil maturation, and cause activation and prolonged survival of the mature cell. IL-5 is unique in that it promotes terminal differentiation of the committed eosinophil precursor and in vivo in mice appears to be sufficient on its own for eosinophil growth from uncommited stem cells. IL-4 selectively upregulates VCAM-1 expression on endothelial cells thus augmenting VLA-4-dependent eosinophil adhesion. The role of eosinophils in disease is complex but in general their numbers are increased in helminthic parasitic disease and atopic allergy and asthma. Eosinophil products can produce many of the pathological features of asthma, and helminthic larvae coated with immunoglobulin or complement are particularly susceptible to eosinophil-mediated cytotoxicity. Eosinopenia is often related to acute inflammation or stress. PMID:7937446

  20. Top-Down Assessment of the Asian Carbon Budget Since the Mid 1990s

    NASA Astrophysics Data System (ADS)

    Thompson, R.; Canadell, J.; Patra, P. K.; Chevallier, F.; Maksyutov, S. S.; Law, R. M.; Ziehn, T.; van der Laan-Luijkx, I. T.; Peters, W.; Ganshin, A.; Zhuravlev, R.; Maki, T.; Nakamura, T.; Shirai, T.; Ishizawa, M.; Saeki, T.; Poulter, B.; Ciais, P.

    2015-12-01

    Atmospheric carbon dioxide (CO2) is the principle driver of anthropogenic climate change. Asia is an important region for the global carbon budget, with four of the world's ten largest national emitters of CO2, but it is also a region with considerable uncertainty in both anthropogenic emissions and land biosphere fluxes of CO2. Furthermore, Asia has undergone rapid economic growth over the past two decades, which has been associated with large increases in fossil fuel emissions, 190% for India and 240% for China between 1990 and 2010. We have used an ensemble of seven atmospheric CO2 inversions and three standard fossil fuel and cement fluxes, based on the inventories of CDIAC, EDGAR and IEA, to determine the land biosphere fluxes for East, South and Southeast Asia, and to ascertain the robustness and overall uncertainty of the results. We find that the East Asian land biosphere was on average a carbon sink of -0.35 ± 0.37 PgC y-1 (median and MAD), or equivalently 17 ± 18% of East Asia's fossil fuel and cement emissions, over 1996 - 2012. Between 1996 - 2001 and 2008 - 2012, we find an increase in the sink of 0.74 ± 0.28 PgC y-1, however the magnitude of this is contingent on the assumed increase in fossil fuel emissions. For South Asia, we find that on average the land biosphere was close to carbon neutral, -0.01 ± 0.20 PgC y-1 over 1996 - 2012 and that there was no significant trend. For Southeast Asia, we find no evidence for a trend in the land biosphere flux over 1996 - 2012 and we cannot determine any difference from carbon neutrality (as assumed a priori by most inversions) with a flux of 0.06 ± 0.29 PgC y-1, throughout this period despite extensive tropical deforestation.

  1. Climatic warming and accompanying changes in the ecological regime of the Black Sea during 1990s

    NASA Astrophysics Data System (ADS)

    Oguz, Temel; Cokacar, Tulay; Malanotte-Rizzoli, Paola; Ducklow, Hugh W.

    2003-09-01

    The Black Sea ecosystem is shown to experience abrupt shifts in its all trophic levels from primary producers to apex predators in 1995-1996. It arises as a manifestation of concurrent changes in its physical climate introduced by intensive warming of its surface waters as well as abrupt increases in the mean sea level and the net annual mean fresh water flux. The warming is evident in the annual-mean sea surface temperature (SST) data by a continuous rise at a rate of ˜0.25°C per year, following a strong cooling phase in 1991-1993. The most intense warming event with ˜2°C increase in the SST took place during winters of the 1994-1996 period. It also coincides with 4 cm yr-1 net sea level rise in the basin, and substantial change in the annual mean net fresh water flux from 150 km3 yr-1 in 1993 to 420 km3 yr-1 in 1997. The subsurface signature of warming is marked by a gradual depletion of the Cold Intermediate Layer (characterized by T < 8°C) throughout the basin during the same period. Winters of the warming phase are characterized by weaker vertical turbulent mixing and upwelling velocity, stronger stratification and, subsequently, reduced upward nutrient supply from the nutricline. From 1996 onward, the major late winter-early spring peak of the classical annual phytoplankton biomass structure observed prior to mid-90s was, therefore, either weakened or disappeared altogether depending on local meteorological and oceanographic conditions during each of these years. The effect of bottom-up limited unfavorable phytoplankton growth is reflected at higher trophic levels (e.g., mesozooplankton, gelatinous macrozooplankton, and pelagic fishes) in the form of their reduced stocks after 1995.

  2. Population growth, internal migration, and environmental degradation in rural areas of developing countries.

    PubMed

    Bilsborrow, R E

    1992-01-01

    Theoretical and empirical issues are explored as related to the extent to which population growth, particularly population redistribution through internal migration, may influence land use patterns and the deterioration of natural resources. Conceptual approaches are presented including a model of the relationships among population growth, migration, and the rural environment. Population growth has direct effects on increased demand for fuelwood and food and land fragmentation. Indirect effects exist through the demand for food which puts pressure on land extensification and intensification which affects soil quality and out migration which affect deforestation and desertification. The prevailing natural resource endowments affect the extent to which extensification of intensification of agriculture takes place in a given time period, the forms in which it occurs, and whether demographic factors play a significant role. Current trends are described for population growth and redistribution, agricultural expansion, and deforestation, desertification, and soil erosion in low-income counties. Data are for 1990 in Asia (23), Latin American (23), and Africa (39) for 85 countries with a population 1 million. Also described are cross-country relationships and the implications. In Africa population growth rates have not changed substantially and the pressure on resources is significant, while dramatic declines have occurred in east and southeast Asia, in Latin America, population growth has changed considerably. Consequences of socioeconomic development are declines in the % of gross domestic product from agriculture and the agricultural labor force. Only Thailand, Nepal, Indonesia, and North Korea out of 23 Asian countries had increases in the % of total land used for agriculture and this resulted in deforestation. Levels were already high in 1965, with 8 countries having 20% of land in agricultural use and 4 countries having 15% in agricultural use. In Bangladesh and

  3. Changes in CH4 emission from rice fields from 1960 to 1990s. 1. Impacts of modern rice technology

    NASA Astrophysics Data System (ADS)

    van der Gon, Hugo Denier

    2000-03-01

    Four countries (Indonesia, Philippines, Thailand, and Nepal) were taken as an example to assess the impact of changes in rice cultivation on methane emissions from rice fields since the 1960s. The change of rice area by type of culture from 1960-1990s is estimated, and its relative contribution to national harvested rice area is calculated and multiplied with an emission factor, to derive the relative methane emission per unit rice land. Relative methane emission per ha rice land has increased since 1960 for all four countries, largely due to an increase in irrigated rice area and partly due to a decrease in upland rice area. Patterns of rice area changes and related emission changes differ considerably among countries. On the basis of the rice area increases between 1960 and the 1990s, significant increases in methane emissions from rice fields due to increases in total rice cultivated area are not to be expected in the future. The impact of modern rice variety adoption is assessed by relating methane emissions to rice production. The organic matter returned to the paddy soil is largely determined by rice biomass production which, given a certain yield, is different for traditional and modern rice varieties. By calculating total organic matter returned to rice paddy soils and assuming a constant fraction to be emitted as methane, rice production and methane emission can be related. The analysis indicates that (1) up to now, rice yield increases in countries with high modern rice variety adoption have not resulted in increased methane emissions per unit of harvested area and, (2) global annual emission from rice fields may be considerably lower than generally assumed. The introduction of modern rice varieties can be regarded as a historical methane emission mitigation strategy because higher rice yields resulted in lower or equal methane emissions.

  4. Changes in CH4 emission from rice fields from 1960 to 1990s: 1. Impacts of modern rice technology

    NASA Astrophysics Data System (ADS)

    Gon, Hugo Denier

    2000-03-01

    Four countries (Indonesia, Philippines, Thailand, and Nepal) were taken as an example to assess the impact of changes in rice cultivation on methane emissions from rice fields since the 1960s. The change of rice area by type of culture from 1960-1990s is estimated, and its relative contribution to national harvested rice area is calculated and multiplied with an emission factor, to derive the relative methane emission per unit rice land. Relative methane emission per ha rice land has increased since 1960 for all four countries, largely due to an increase in irrigated rice area and partly due to a decrease in upland rice area. Patterns of rice area changes and related emission changes differ considerably among countries. On the basis of the rice area increases between 1960 and the 1990s, significant increases in methane emissions from rice fields due to increases in total rice cultivated area are not to be expected in the future. The impact of modern rice variety adoption is assessed by relating methane emissions to rice production. The organic matter returned to the paddy soil is largely determined by rice biomass production which, given a certain yield, is different for traditional and modern rice varieties. By calculating total organic matter returned to rice paddy soils and assuming a constant fraction to be emitted as methane, rice production and methane emission can be related. The analysis indicates that (1) up to now, rice yield increases in countries with high modern rice variety adoption have not resulted in increased methane emissions per unit of harvested area and, (2) global annual emission from rice fields may be considerably lower than generally assumed. The introduction of modern rice varieties can be regarded as a historical methane emission mitigation strategy because higher rice yields resulted in lower or equal methane emissions.

  5. Petroleum geology of heavy oil in the Oriente basin of Ecuador: Exploration and exploitation challenge for the 1990s

    SciTech Connect

    Leadholm, R.H. )

    1990-05-01

    Published Ecuadorian government forecasts suggest that Oriente basin light oil (21-32{degree} API) production may start to decline in the early to mid-1990s. To maintain stabilized production into the next century, heavy oil reserves (10-20{degree} API) will have to be aggressively exploited. The Oriente's undeveloped proven plus probable heavy reserves are substantial and are expected to exceed 0.5 billion bbl. A recent discovery made by Conoc Ecuador Ltd., operator of Block 16 for a group which consists of O.P.I.C., Maxus, Nomeco, Murphy and Canam, is a good model for future exploration and exploitation of heavy oil in the remote eastern regions of the basin. Amo-1 tested a low-relief anticline (less than 100 ft vertical closure) and encountered 10-20{degree} API oil in five Cretaceous sandstone reservoirs (8,000-10,000 ft depth). Cumulative test production was 1,062 BOPD. Subsequent drilling along the trend resulted in three additional discoveries. The Cretaceous sands were transported from the Brazilian shield by the westward flowing proto-Amazon River and were deposited in fluviodeltaic, tidal, and high-energy marginal marine environments. Air permeabilities are high and geometric mean values approaching several darcies. Porosities average 18-22% in generally well-consolidated sands. The heavy oils are the result of mild biodegradation and/or expulsion from a thermally immature source. Oil-to-oil correlations suggest that all of the basin oils have the same or similar origin, probably marine calcareous shales of the Cretaceous Napo formation. The Block 16 project will provide a major step toward the strategic exploitation of the Oriente basin's heavy oil reserves, when it comes on stream in the early 1990s.

  6. Sensitizing events as trigger for discursive renewal and institutional change in Flanders’ environmental health approach, 1970s-1990s

    PubMed Central

    2013-01-01

    Background Sensitizing events may trigger and stimulate discursive renewal. From a discursive institutional perspective, changing discourses are the driving force behind the institutional dynamics of policy domains. Theoretically informed by discursive institutionalism, this article assesses the impact of a series of four sensitizing events that triggered serious environmental health concerns in Flanders between the 1970s till the 1990s, and led onto the gradual institutionalization of a Flemish environmental health arrangement. Methods The Policy Arrangement Approach is used as the analytical framework to structure the empirical results of the historical analysis based on document analysis and in-depth interviews. Results Until the 1990s, environmental health was characterized as an ad hoc policy field in Flanders, where agenda setting was based on sensitizing events – also referred to as incident-driven. Each of these events contributed to a gradual rethinking of the epistemological discourses about environmental health risks and uncertainties. These new discourses were the driving forces behind institutional dynamics as they gradually resulted in an increased need for: 1) long-term, policy-oriented, interdisciplinary environmental health research; 2) policy coordination and integration between the environmental and public health policy fields; and 3) new forms of science-policy interactions based on mutual learning. These changes are desirable in order to detect environmental health problems as fast as possible, to react immediately and communicate appropriately. Conclusions The series of four events that triggered serious environmental health concerns in Flanders provided the opportunity to rethink and re-organize the current affairs concerning environmental health and gradually resulted into the institutionalization of a Flemish environmental health arrangement. PMID:23758822

  7. Did Devonian shale wells drilled during the 1980`s and early 1990`s in West Virginia measure up to expectations?

    SciTech Connect

    Hohn, M.E.; McDowell, R.R.; Matchen, D.L.; Woods, T.J.

    1996-09-01

    In the mid-1980`s, a model of future Devonian shale drilling and production was prepared for the Gas Research Institute (GRI). In late 1995, the West Virginia Geological and Economic Survey (WVGES) was contracted by GRI to evaluate actual drilling and production in the 1980`s and early 1990`s and compare these data to the predictions made in the existing model. Drilling activity data were compiled for the years 1979-1993 for all wells drilled, and for all Devonian shale wells drilled. Monthly and annual production data were summarized for both categories. The Devonian shale wells were subdivided into two subsets: (1) the western black shales trend and (2) the eastern black and gray shales and siltstones trend, according to the play definitions used in the {open_quotes}Atlas of Major Appalachian Gas Reservoirs{close_quotes}. Devonian shale wells were subdivided into vintages by completion year. Finally, each Devonian shale well was assigned to a 30 minute geographic grid or {open_quotes}cell{close_quotes} and production data were compiled and compared between cells. Analysis of the data led to the following conclusions: fewer shale wells were being drilled in the early 1990s, but these wells had better recoveries than the wells drilled in the 1980s. Some grid cells showed higher recoveries for the black and gray shales and siltstones play than in cells with black shale reservoirs alone. These higher recoveries perhaps can be attributed to the common practice of completing and producing shallower zones (i.e. Mississippian sandstones) in addition to the Devonian shales.

  8. Population growth and natural resource use: do we need to despair of Africa?.

    PubMed

    Tiffen, M; Mortimore, M

    1993-01-01

    The authors make the case that population growth can lead to increases in agricultural output per head on a sustainable basis. This argument, originally developed by E. Boserup, is "illustrated by a study of Machakos District, Kenya during 1930-1960, which shows that, if policies are supportive, agricultural and non-farm incomes grow faster than even the rapid population growth rate experienced in Africa. Land use capability is not fixed, but can be transformed by investment, new technologies and good management. Lack of investment and consequent degradation are most likely at low population densities. While the study cannot foretell the future, Java illustrates a similar theme at even higher densities." PMID:12287204

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Population size, growth and movements of Anguilla australis in a small lake.

    PubMed

    Jellyman, D J; Crow, S K

    2016-06-01

    To study growth rates, movements and estimate population size of shortfin eels Anguilla australis in a small lake (2·5 ha) near Christchurch, New Zealand, 617 A. australis were tagged with PIT tags. Tag retention was high (95%) and over the seven recapture events spread over 2 years, 55% of tagged A. australis were recaptured. Growth of recaptured A. australis averaged 13·1 mm year(-1) and declined slightly with increasing total length. Distance moved from original capture site increased with increasing time at large. Population estimates of A. australis > 400 mm (susceptible to capture by fyke net) from recaptures of individuals averaged 1451 A. australis, with a biomass of 170 kg ha(-1) . An average of 6·6% of the estimated total population matured as male silver A. australis each year. Results from radio-tracking of four A. australis gave an average nightly foraging area of 2780 m(2) , and there was no apparent preference for inshore movement (within 5-6 m of the shoreline) or offshore movement. Fyke-net efficiency (total catch relative to the estimated total population available to each net) measured over four consecutive nights fishing was 88%. The lack of precision of the shoreline triangulation system used, ±10 m, meant that the positional data were considered too coarse to be used in a proposed novel population estimation technique based on determining population size within foraging areas. PMID:27126719

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

    PubMed

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

    2015-06-01

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

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

    PubMed Central

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

    2015-01-01

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

  13. Tropical forest cover change in the 1990s and options for future monitoring

    PubMed Central

    Mayaux, Philippe; Holmgren, Peter; Achard, Frédéric; Eva, Hugh; Stibig, Hans-Jürgen; Branthomme, Anne

    2005-01-01

    Despite the importance of the world's humid tropical forests, our knowledge concerning their rates of change remains limited. Two recent programmes (FAO 2000 Forest Resources Assessment and TREES II), exploiting the global imaging capabilities of Earth observing satellites, have recently been completed to provide information on the dynamics of tropical forest cover. The results from these independent studies show a high degree of conformity and provide a good understanding of trends at the pan-tropical level. In 1990 there were some 1150 million ha of tropical rain forest with the area of the humid tropics deforested annually estimated at 5.8 million ha (approximately twice the size of Belgium). A further 2.3 million ha of humid forest is apparently degraded annually through fragmentation, logging and/or fires. In the sub-humid and dry tropics, annual deforestation of tropical moist deciduous and tropical dry forests comes to 2.2 and 0.7 million ha, respectively. Southeast Asia is the region where forests are under the highest pressure with an annual change rate of −0.8 to −0.9%. The annual area deforested in Latin America is large, but the relative rate (−0.4 to −0.5%) is lower, owing to the vast area covered by the remaining Amazonian forests. The humid forests of Africa are being converted at a similar rate to those of Latin America (−0.4 to −0.5% per year). During this period, secondary forests have also been established, through re-growth on abandoned land and forest plantations, but with different ecological, biophysical and economic characteristics compared with primary forests. These trends are significant in all regions, but the extent of new forest cover has proven difficult to establish. These results, as well as the lack of more detailed knowledge, clearly demonstrate the need to improve sound scientific evidence to support policy. The two projects provide useful guidance for future monitoring efforts in the context of multilateral

  14. Tropical forest cover change in the 1990s and options for future monitoring.

    PubMed

    Mayaux, Philippe; Holmgren, Peter; Achard, Frédéric; Eva, Hugh; Stibig, Hans-Jürgen; Branthomme, Anne

    2005-02-28

    Despite the importance of the world's humid tropical forests, our knowledge concerning their rates of change remains limited. Two recent programmes (FAO 2000 Forest Resources Assessment and TREES II), exploiting the global imaging capabilities of Earth observing satellites, have recently been completed to provide information on the dynamics of tropical forest cover. The results from these independent studies show a high degree of conformity and provide a good understanding of trends at the pan-tropical level. In 1990 there were some 1150 million ha of tropical rain forest with the area of the humid tropics deforested annually estimated at 5.8 million ha (approximately twice the size of Belgium). A further 2.3 million ha of humid forest is apparently degraded annually through fragmentation, logging and/or fires. In the sub-humid and dry tropics, annual deforestation of tropical moist deciduous and tropical dry forests comes to 2.2 and 0.7 million ha, respectively. Southeast Asia is the region where forests are under the highest pressure with an annual change rate of -0.8 to -0.9%. The annual area deforested in Latin America is large, but the relative rate (-0.4 to -0.5%) is lower, owing to the vast area covered by the remaining Amazonian forests. The humid forests of Africa are being converted at a similar rate to those of Latin America (-0.4 to -0.5% per year). During this period, secondary forests have also been established, through re-growth on abandoned land and forest plantations, but with different ecological, biophysical and economic characteristics compared with primary forests. These trends are significant in all regions, but the extent of new forest cover has proven difficult to establish. These results, as well as the lack of more detailed knowledge, clearly demonstrate the need to improve sound scientific evidence to support policy. The two projects provide useful guidance for future monitoring efforts in the context of multilateral environmental

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

    USGS Publications Warehouse

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

    2015-01-01

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

  16. The use of intraallelic variability for testing neutrality and estimating population growth rate.

    PubMed Central

    Slatkin, M; Bertorelle, G

    2001-01-01

    To better understand the forces affecting individual alleles, we introduce a method for finding the joint distribution of the frequency of a neutral allele and the extent of variability at closely linked marker loci (the intraallelic variability). We model three types of intraallelic variability: (a) the number of nonrecombinants at a linked biallelic marker locus, (b) the length of a conserved haplotype, and (c) the number of mutations at a linked marker locus. If the population growth rate is known, the joint distribution provides the basis for a test of neutrality by testing whether the observed level of intraallelic variability is consistent with the observed allele frequency. If the population growth rate is unknown but neutrality can be assumed, the joint distribution provides the likelihood of the growth rate and leads to a maximum-likelihood estimate. We apply the method to data from published data sets for four loci in humans. We conclude that the Delta32 allele at CCR5 and a disease-associated allele at MLH1 arose recently and have been subject to strong selection. Alleles at PAH appear to be neutral and we estimate the recent growth rate of the European population to be approximately 0.027 per generation with a support interval of (0.017-0.037). Four of the relatively common alleles at CFTR also appear to be neutral but DeltaF508 appears to be significantly advantageous to heterozygous carriers. PMID:11404347

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

    PubMed

    Hashmi, S S

    1990-01-01

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

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

    PubMed

    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. PMID:21528359

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

    PubMed

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

    2015-01-01

    In Singapore, the frequency and magnitude of dengue epidemics have increased significantly over the past 40 years. It is important to understand the main drivers for the rapid increase in dengue incidence. We studied the relative contributions of putative drivers for the rise of dengue in Singapore: population growth, climate parameters and international air passenger arrivals from dengue endemic countries, for the time period of 1974 until 2011. We used multivariable Poisson regression models with the following predictors: Annual Population Size; Aedes Premises Index; Mean Annual Temperature; Minimum and Maximum Temperature Recorded in each year; Annual Precipitation and Annual Number of Air Passengers arriving from dengue-endemic South-East Asia to Singapore. The relative risk (RR) of the increase in dengue incidence due to population growth over the study period was 42.7, while the climate variables (mean and minimum temperature) together explained an RR of 7.1 (RR defined as risk at the end of the time period relative to the beginning and goodness of fit associated with the model leading to these estimates assessed by pseudo-R2 equal to 0.83). Estimating the extent of the contribution of these individual factors on the increasing dengue incidence, we found that population growth contributed to 86% while the residual 14% was explained by increase in temperature. We found no correlation with incoming air passenger arrivals into Singapore from dengue endemic countries. Our findings have significant implications for predicting future trends of the dengue epidemics given the rapid urbanization with population growth in many dengue endemic countries. It is time for policy-makers and the scientific community alike to pay more attention to the negative impact of urbanization and urban climate on diseases such as dengue. PMID:26322517

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

    PubMed Central

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

    2015-01-01

    In Singapore, the frequency and magnitude of dengue epidemics have increased significantly over the past 40 years. It is important to understand the main drivers for the rapid increase in dengue incidence. We studied the relative contributions of putative drivers for the rise of dengue in Singapore: population growth, climate parameters and international air passenger arrivals from dengue endemic countries, for the time period of 1974 until 2011. We used multivariable Poisson regression models with the following predictors: Annual Population Size; Aedes Premises Index; Mean Annual Temperature; Minimum and Maximum Temperature Recorded in each year; Annual Precipitation and Annual Number of Air Passengers arriving from dengue-endemic South-East Asia to Singapore. The relative risk (RR) of the increase in dengue incidence due to population growth over the study period was 42.7, while the climate variables (mean and minimum temperature) together explained an RR of 7.1 (RR defined as risk at the end of the time period relative to the beginning and goodness of fit associated with the model leading to these estimates assessed by pseudo-R2 equal to 0.83). Estimating the extent of the contribution of these individual factors on the increasing dengue incidence, we found that population growth contributed to 86% while the residual 14% was explained by increase in temperature. We found no correlation with incoming air passenger arrivals into Singapore from dengue endemic countries. Our findings have significant implications for predicting future trends of the dengue epidemics given the rapid urbanization with population growth in many dengue endemic countries. It is time for policy-makers and the scientific community alike to pay more attention to the negative impact of urbanization and urban climate on diseases such as dengue. PMID:26322517

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Loss of foundation species increases population growth of exotic forbs in sagebrush steppe.

    PubMed

    Prevéy, Janet S; Germino, Matthew J; Huntly, Nancy J

    2010-10-01

    The invasion and spread of exotic plants following land disturbance threatens semiarid ecosystems. In sagebrush steppe, soil water is scarce and is partitioned between deep-rooted perennial shrubs and shallower-rooted native forbs and grasses. Disturbances commonly remove shrubs, leaving grass-dominated communities, and may allow for the exploitation of water resources by the many species of invasive, tap-rooted forbs that are increasingly successful in this habitat. We hypothesized that exotic forb populations would benefit from increased soil water made available by removal of sagebrush, a foundation species capable of deep-rooting, in semiarid shrub-steppe ecosystems. To test this hypothesis, we used periodic matrix models to examine effects of experimental manipulations of soil water on population growth of two exotic forb species, Tragopogon dubius and Lactuca serriola, in sagebrush steppe of southern Idaho, USA. We used elasticity analyses to examine which stages in the life cycle of T. dubius and L. serriola had the largest relative influence on population growth. We studied the demography of T. dubius and L. serriola in three treatments: (1) control, in which vegetation was not disturbed, (2) shrubs removed, or (3) shrubs removed but winter-spring recharge of deep-soil water blocked by rainout shelters. The short-term population growth rate (Lambda) of T. dubius in the shrub-removal treatment was more than double that of T. dubius in either sheltered or control treatments, both of which had limited soil water. All L. serriola individuals that emerged in undisturbed sagebrush plots died, whereas Lambda of L. serriola was high (Lambda > 2.5) in all shrub-removal plots, whether they had rainout shelters or not. Population growth of both forbs in all treatments was most responsive to flowering and seed production, which are life stages that should be particularly reliant on deep-soil water, as well as seedling establishment, which is important to most plant

  3. Mammalian Herbivores Alter the Population Growth and Spatial Establishment of an Early-Establishing Grassland Species.

    PubMed

    Sullivan, Lauren L; Danielson, Brent J; Harpole, W Stanley

    2016-01-01

    Plant-herbivore interactions influence the establishment context of plant species, as herbivores alter the community context in which individual species establish, and the spatial relationship between individuals and their source population as plants invade. This relationship can be described using an establishment kernel, which takes into account movement through seed dispersal, and subsequent establishment of adults. Mammalian herbivores are hypothesized to influence plant population growth and establishment through a combination of consumption of seeds and seedlings, and movement of seeds. While the movement abilities of plants are well known, we have very few empirical mechanistic tests of how biotic factors like mammalian herbivores influence this spread potential. As herbivores of all sizes are abundant on the landscape, we asked the question, how do mammalian herbivores influence the population growth, spatial establishment, and the community establishment context of an early-recruiting native prairie legume, Chamaecrista fasciculata? We planted C. fasciculata in source populations within a four-acre tallgrass prairie restoration in plots with and without herbivores, and monitored its establishment with respect to distance from the source populations. We found that herbivores decreased population growth, and decreased the mean and range establishment distance. Additionally, C. fasciculata established more often without herbivores, and when surrounded by weedy, annual species. Our results provide insight into how the interactions between plants and herbivores can alter the spatial dynamics of developing plant communities, which is vital for colonization and range spread with fragmentation and climate change. Mammalian herbivores have the potential to both slow rates of establishment, but also determine the types of plant communities that surround invading species. Therefore, it is essential to consider the herbivore community when attempting to restore

  4. Mammalian Herbivores Alter the Population Growth and Spatial Establishment of an Early-Establishing Grassland Species

    PubMed Central

    Sullivan, Lauren L.; Danielson, Brent J.; Harpole, W. Stanley

    2016-01-01

    Plant-herbivore interactions influence the establishment context of plant species, as herbivores alter the community context in which individual species establish, and the spatial relationship between individuals and their source population as plants invade. This relationship can be described using an establishment kernel, which takes into account movement through seed dispersal, and subsequent establishment of adults. Mammalian herbivores are hypothesized to influence plant population growth and establishment through a combination of consumption of seeds and seedlings, and movement of seeds. While the movement abilities of plants are well known, we have very few empirical mechanistic tests of how biotic factors like mammalian herbivores influence this spread potential. As herbivores of all sizes are abundant on the landscape, we asked the question, how do mammalian herbivores influence the population growth, spatial establishment, and the community establishment context of an early-recruiting native prairie legume, Chamaecrista fasciculata? We planted C. fasciculata in source populations within a four-acre tallgrass prairie restoration in plots with and without herbivores, and monitored its establishment with respect to distance from the source populations. We found that herbivores decreased population growth, and decreased the mean and range establishment distance. Additionally, C. fasciculata established more often without herbivores, and when surrounded by weedy, annual species. Our results provide insight into how the interactions between plants and herbivores can alter the spatial dynamics of developing plant communities, which is vital for colonization and range spread with fragmentation and climate change. Mammalian herbivores have the potential to both slow rates of establishment, but also determine the types of plant communities that surround invading species. Therefore, it is essential to consider the herbivore community when attempting to restore

  5. The effects of population density on juvenile growth rate in white-tailed deer.

    PubMed

    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. PMID:25148782

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

    NASA Astrophysics Data System (ADS)

    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.

  7. The evolution of paternal care can lead to population growth in artificial societies.

    PubMed

    Salgado, Mauricio

    2015-09-01

    Evolutionary models of paternal care predict that when female reproductive effort is higher than male reproductive effort, selection might favour the emergence of unconditional male cooperation towards females, even when the latter group does not reciprocate. However, previous models have assumed constant population sizes, so the ecology of interacting individuals and its effects on population dynamics have been neglected. This paper reports an agent-based model that incorporates ecological dynamics into evolutionary game dynamics by allowing populations to vary. As previous models demonstrate, paternal care only evolves when female reproductive effort is higher than that of males, and the optimal strategy for females is to exploit male unconditional cooperation. The model also shows that evolution of this behaviour drives some simulations towards regimes of population growth. Thanks to the evolution of paternal care, females׳ inter-birth intervals are shortened and causing them to reproduce faster. Thus, it is suggested that the evolution of paternal care in species with differential reproductive effort between sexes could be associated to population growth. Nevertheless, the modelled evolutionary dynamics are stochastic, so differences in reproductive effort are necessary but not sufficient conditions for the evolution of paternal care. PMID:26051195

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

    USGS Publications Warehouse

    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.

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

    PubMed

    Smith, J D

    1995-01-01

    Southern Africa's high rate of population growth and widespread poverty have serious implications for the region's social infrastructure. Large increases in the school-age population have undermined efforts to improve the quality of education since all resources are directed toward expansion of availability. To achieve a teacher-pupil ratio of 1:40 at the primary level and 1:35 at the secondary level, an estimated additional 50,000 classrooms would be required. Also jeopardized by high fertility is access to health services, safe water, and sanitation. In Mozambique, for example, where only 30% of the population has access to health services, the under-five years mortality rate is 297/1000 live births and the physician-population ratio is 1:37,970. Substandard housing, homelessness, congestion, deteriorating public services, pollution, and crime dominate urban areas. The single most effective intervention to reduce population growth in Southern Africa is female education. Women without a secondary education bear an average of seven children; if 40% of women attend secondary school, this drops to three children. Thus, governments must make gender equality a central focus of development planning and ensure that women are participants in this process. Property and inheritance laws that serve to increase the economic need for early marriage should be eliminated. Public health programs, including family planning, must be expanded. Finally, women's organizations should be strengthened and urged to foster female empowerment. PMID:12346213

  10. Population Growth of Pratylenchus penetrans on Winter Cover Crops Grown in the Pacific Northwest

    PubMed Central

    Forge, T. A.; Ingham, R. E.; Kaufman, D.; Pinkerton, J. N.

    2000-01-01

    Population growth of Pratylenchus penetrans on 13 fall and winter cover crops was studied in the greenhouse and field. All crops except oat cv. Saia supported population growth of P. penetrans in greenhouse experiments, although the response of P. penetrans to oat cv. Saia varied considerably between experiments. The mean ratio of the final population density/initial population density (Pf/Pi) after 16 weeks for P. penetrans added to a greenhouse soil mix was 0.09, whereas Pf/Pi values after 10 weeks for two experiments with naturally infested soil were 0.95 and 2.3. Although P. penetrans increased on sudangrass cv. Trudan 8 and sudangrass × sorghum hybrid cv. SS 222, subsequent incorporation of sudangrass vegetation into soil reduced P. penetrans populations to preplant levels. Field experiments were inconclusive but suggested that oat cv. Saia or rye cv. Wheeler may be better choices for winter cover than weed-contaminated fallow or other crops on P. penetrans-infested sites in the Pacific Northwest. PMID:19270948

  11. The Contribution of Population Health and Demographic Change to Economic Growth in China and India.

    PubMed

    Bloom, David E; Canning, David; Hu, Linlin; Liu, Yuanli; Mahal, Ajay; Yip, Winnie

    2010-03-01

    We find that a cross-country model of economic growth successfully tracks the growth takeoffs in China and India. The major drivers of the predicted takeoffs are improved health, increased openness to trade, and a rising labor force-to-population ratio due to fertility decline. We also explore the effect of the reallocation of labor from low-productivity agriculture to the higher-productivity industry and service sectors. Including the money value of longevity improvements in a measure of full income reduces the gap between the magnitude of China's takeoff relative to India's due to the relative stagnation in life expectancy in China since 1980. PMID:20419074

  12. The Contribution of Population Health and Demographic Change to Economic Growth in China and India

    PubMed Central

    Bloom, David E.; Canning, David; Hu, Linlin; Liu, Yuanli; Mahal, Ajay; Yip, Winnie

    2010-01-01

    We find that a cross-country model of economic growth successfully tracks the growth takeoffs in China and India. The major drivers of the predicted takeoffs are improved health, increased openness to trade, and a rising labor force-to-population ratio due to fertility decline. We also explore the effect of the reallocation of labor from low-productivity agriculture to the higher-productivity industry and service sectors. Including the money value of longevity improvements in a measure of full income reduces the gap between the magnitude of China's takeoff relative to India's due to the relative stagnation in life expectancy in China since 1980. PMID:20419074

  13. A Dramatic Regime Shift in Rainfall Predictability Related to the Ningaloo Niño/Niña in the Late 1990s

    NASA Astrophysics Data System (ADS)

    Doi, T.; Behera, S. K.; Yamagata, T.

    2014-12-01

    The global warming and the Interdecadal Pacific Oscillation (IPO) started influencing the coastal ocean off Western Australia, leading to a dramatic change in the regional climate predictability. The warmed ocean started driving rainfall regionally there after the late 1990s. Because of this, rainfall predictability off Western Australia on a seasonal time scale was drastically enhanced in the late 1990s; it is significantly predictable 5 months ahead after the late 1990s. The high prediction skill of the rainfall in recent decades encourages development of an early warning system of Ningaloo Niño/Niña events to mitigate possible societal as well as agricultural impacts in the granary.

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

    ERIC Educational Resources Information Center

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

    2005-01-01

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

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

    PubMed

    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. PMID:23516730

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

    ERIC Educational Resources Information Center

    Hobart, Christine L.

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

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

    USGS Publications Warehouse

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

    2006-01-01

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

  18. Enhanced (hydrodynamic) transport induced by population growth in reaction–diffusion systems with application to population genetics

    PubMed Central

    Vlad, Marcel Ovidiu; Cavalli-Sforza, L. Luca; Ross, John

    2004-01-01

    We consider a system made up of different physical, chemical, or biological species undergoing replication, transformation, and disappearance processes, as well as slow diffusive motion. We show that for systems with net growth the balance between kinetics and the diffusion process may lead to fast, enhanced hydrodynamic transport. Solitary waves in the system, if they exist, stabilize the enhanced transport, leading to constant transport speeds. We apply our theory to the problem of determining the original mutation position from the current geographic distribution of a given mutation. We show that our theory is in good agreement with a simulation study of the mutation problem presented in the literature. It is possible to evaluate migratory trajectories from measured data related to the current distribution of mutations in human populations. PMID:15231998

  19. Models for optimal harvest with convex function of growth rate of a population

    SciTech Connect

    Lyashenko, O.I.

    1995-12-10

    Two models for growth of a population, which are described by a Cauchy problem for an ordinary differential equation with right-hand side depending on the population size and time, are investigated. The first model is time-discrete, i.e., the moments of harvest are fixed and discrete. The second model is time-continuous, i.e., a crop is harvested continuously in time. For autonomous systems, the second model is a particular case of the variational model for optimal control with constraints investigated in. However, the prerequisites and the method of investigation are somewhat different, for they are based on Lemma 1 presented below. In this paper, the existence and uniqueness theorem for the solution of the discrete and continuous problems of optimal harvest is proved, and the corresponding algorithms are presented. The results obtained are illustrated by a model for growth of the light-requiring green alga Chlorella.

  20. Substance abuse studies and prevention efforts among Arabs in the 1990s in Israel, Jordan and the Palestinian Authority--a literature review.

    PubMed

    Weiss, S; Sawa, G H; Abdeen, Z; Yanai, J

    1999-02-01

    This paper is the result of a collaborative project of Israeli, Jordanian and Palestinian scientists gathered to reveal the current extent of substance abuse and efforts at prevention among Arabs in Israel, Jordan and the Palestinian Authority territories, in order to identify needs and suggest future collaborative activities and directions for regional cooperation. The article provides data and covers the current state of substance abuse prevention and research among Moslems, Christians and Druze in the trilateral region in the 1990s by reviewing prevention materials and studies published in the professional literature, as well as in reports and Doctoral and Master's theses in Arabic, which have been located in academic libraries and other institutions, in the framework of a comprehensive search. This manuscript is the first to summarize Jordanian and Palestinian findings in the substance abuse domain. The review shows that most of the Israeli research in the Arab sector deals with alcohol use among youth, that the majority of Jordanian studies focus on illicit drug use, that the research among Palestinians is in its infancy, and that comprehensive prevention programs are lacking in the trilateral region. It describes the key results of most of the 12 Israeli studies among Arabs, 11 Jordanian studies and four Palestinian studies. It reveals that drug abuse among Israeli Arab students is probably more prevalent than among Jewish adolescents, that the typical Jordanian drug addict has a higher level of education than the typical Palestinian drug addict, and that the Palestinian is more likely to be a multiple drug user. Recommendations for future activities include organization of a regional collaborative workshop in order to establish data collection systems for basic statistics relevant to drug abuse and development of comprehensive prevention programs, as well as studies in the substance abuse domain concerning knowledge, attitudes and behavior among the general

  1. Effects of density and fire on the vital rates and population growth of a perennial goldenaster

    PubMed Central

    Gornish, Elise S.

    2013-01-01

    Intraspecific density effects are generally associated with other factors, like disturbance. Therefore, the ways in which density effects might interact with disturbance to modify the relationships between vital rates and population growth must be understood. I quantified the effects of density on the life-history stages of the perennial composite Pityopsis aspera over 3 years, the span of which included years in which fire did and did not occur. In an experimental study, I estimated the survival, growth and reproduction for shoots in plots established across a natural range of densities in Florida, USA. In a novel analysis, a regression-design life-table response experiment was used to determine which transitions were associated with density, how they contributed to differences in estimated population growth rates and how this relationship differed as a result of fire. The shape of the relationship between population growth rate (λ) and density was modified by fire, primarily as a result of contributions from adult flowering stasis and survival, and first-year survival probabilities. Fire modified and even reversed the effect of extreme densities on adult flowering stasis and survival and of first-year survival, resulting in more positive contributions from these transitions to λ at the lowest and highest density values. These results demonstrate the first application of a regression-design life-table response experiment to elucidating the interactive effects of density and fire. They highlight the utility of this approach for both capturing the complex dynamics of populations and establishing a means of determining how vital rates might contribute to differences in demography across densities.

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

    PubMed

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

    2014-09-01

    Current literature acknowledges the effect of food structure on bacterial dynamics. Most studies introduce this "structure" factor using a single gelling agent, resulting in a homogeneous environment, whereas in practice most food products are heterogeneous. Therefore, this study focuses on heterogeneous protein-polysaccharide mixtures, based on gelatin and dextran. These mixtures show phase separation, leading to a range of heterogeneous microstructures by adjusting relative concentrations of both gelling agents. Based on confocal microscope observations, the growth of Escherichia coli in gelatin-dextran systems was observed to occur in the dextran phase. To find a relation between microscopic and population behavior, growth experiments were performed in binary and singular gelatin-dextran systems and culture broth at 23.5°C, with or without adding 2.9% (wt/vol) NaCl. The Baranyi and Roberts growth model was fitted to the experimental data and parameter estimates were statistically compared. For salted binary mixtures, a decrease in the population maximum cell density was observed with increasing gelatin concentration. In this series, for one type of microstructure, i.e., a gelatin matrix phase with a disperse dextran phase, the maximum cell density decreased with decreasing percentage of dextran phase. However, this relation no longer held when other types of microstructure were observed. Compared to singular systems, adding a second gelling agent in the presence of NaCl had an effect on population lag phases and maximum cell densities. For unsalted media, the growth parameters of singular and binary mixtures were comparable. Introducing this information into mathematical models leads to more reliable growth predictions and enhanced food safety. PMID:24951795

  3. Dynamics and forecasting of population growth and urban expansion in Srinagar City - A Geospatial Approach

    NASA Astrophysics Data System (ADS)

    Farooq, M.; Muslim, M.

    2014-11-01

    The urban areas of developing countries are densely populated and need the use of sophisticated monitoring systems, such as remote sensing and geographical information systems (GIS). The urban sprawl of a city is best understood by studying the dynamics of LULC change which can be easily generated by using sequential satellite images, required for the prediction of urban growth. Multivariate statistical techniques and regression models have been used to establish the relationship between the urban growth and its causative factors and for forecast of the population growth and urban expansion. In Srinagar city, one of the fastest growing metropolitan cities situated in Jammu and Kashmir State of India, sprawl is taking its toll on the natural resources at an alarming pace. The present study was carried over a period of 40 years (1971-2011), to understand the dynamics of spatial and temporal variability of urban sprawl. The results reveal that built-up area has increased by 585.08 % while as the population has increased by 214.75 %. The forecast showed an increase of 246.84 km2 in built-up area which exceeds the overall carrying capacity of the city. The most common conversions were also evaluated.

  4. The relationship between population growth and real assessed market values: note.

    PubMed

    Gamble, H B; Downing, R H

    1985-07-01

    Various indices are commonly used to measure growth or decline in communities and regions, but this article suggests another measure which is fairly easy to obtain--the change over time in real assessed market values. Computer storage and analysis of real estate assessment and sales data make it possible to determine accurate true assessment ratios which can be used to calculate reasonable estimates of market values. This article shows the relationship between population growth from 1970 to 1980 and the changes in real assessed market values of various property classes for over 400 Pennsylvania townships. This can provide insight into the kind and nature of community change. The most noteworthy aspect of these data, not apparent in conventional growth measures, is the magnitude of increases of residential property values in all growth categories, but particularly in the high growth townships. This kind of data could be calculated by countries or by regions; this might be more informative and useful to planners and researchers in such form. Comparing local data to regional, community, or state landmark data can help identify strengths and weaknesses or the particular nature of a community's growth. PMID:12314193

  5. Estimation of contributions to population growth: a reverse-time capture-recapture approach

    USGS Publications Warehouse

    Nichols, J.D.; Hines, J.E.; Lebreton, J.D.; Pradel, R.

    2000-01-01

    We consider methods for estimating the relative contributions of different demographic components, and their associated vital rates, to population growth. We identify components of the population at time i (including a component for animals not in the population at i). For each such component we ask the following question: 'What is the probability that an individual randomly selected from the population at time i + 1 was a member of this component at i?' The estimation methods for these probabilities ((i) are based on capture-recapture studies of marked animal populations and use reverse-time modeling. We consider several different sampling situations and present example analyses for meadow voles, Microtus pennsylvanicus. The relationship between these (i parameters and elasticities (and other parameters based on projection matrix asymptotics) is noted and discussed. We conclude by suggesting that model-based asymptotics be viewed as demographic theory and that direct estimation approaches be used to test this theory with data from sampled populations with marked animals.

  6. Life-history correlates of maximum population growth rates in marine fishes.

    PubMed Central

    Denney, Nicola H; Jennings, Simon; Reynolds, John D

    2002-01-01

    Theory predicts that populations of animals with late maturity, low fecundity, large body size and low body growth rates will have low potential rates of population increase at low abundance. If this is true, then these traits may be used to predict the intrinsic rate of increase for species or populations, as well as extinction risks. We used life-history and population data for 63 stocks of commercially exploited fish species from the northeast Atlantic to test relationships between life-history parameters and the rate of population increase at low abundance. We used cross-taxonomic analyses among stocks and among species, and analyses that accounted for phylogenetic relationships. These analyses confirmed that large-bodied, slow-growing stocks and species had significantly lower rates of recruitment and adult production per spawning adult at low abundance. Furthermore, high ages at maturity were significantly correlated with low maximum recruit production. Contrary to expectation, fecundity was significantly negatively related to recruit production, due to its positive relationship with maximum body size. Our results support theoretical predictions, and suggest that a simply measured life-history parameter can provide a useful tool for predicting rates of recovery from low population abundance. PMID:12427316

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

    PubMed

    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. PMID:17851205

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

    PubMed Central

    Tsai, Hsin Y.; Hamilton, Alastair; Guy, Derrick R.; Tinch, Alan E.; Bishop, Steve C.; Houston, Ross D.

    2015-01-01

    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. PMID:26703584

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

    PubMed

    Shaw, R P

    1992-02-01

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

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

    EPA Science Inventory

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

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

    PubMed Central

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

    2014-01-01

    The differences in demographic and life-history processes between organisms living in the same population have important consequences for ecological and evolutionary dynamics. Modern statistical and computational methods allow the investigation of individual and shared (among homogeneous groups) determinants of the observed variation in growth. We use an Empirical Bayes approach to estimate individual and shared variation in somatic growth using a von Bertalanffy growth model with random effects. To illustrate the power and generality of the method, we consider two populations of marble trout Salmo marmoratus living in Slovenian streams, where individually tagged fish have been sampled for more than 15 years. We use year-of-birth cohort, population density during the first year of life, and individual random effects as potential predictors of the von Bertalanffy growth function's parameters k (rate of growth) and (asymptotic size). Our results showed that size ranks were largely maintained throughout marble trout lifetime in both populations. According to the Akaike Information Criterion (AIC), the best models showed different growth patterns for year-of-birth cohorts as well as the existence of substantial individual variation in growth trajectories after accounting for the cohort effect. For both populations, models including density during the first year of life showed that growth tended to decrease with increasing population density early in life. Model validation showed that predictions of individual growth trajectories using the random-effects model were more accurate than predictions based on mean size-at-age of fish. PMID:25211603

  12. Population growth study of the rotifer Brachionus sp. fed with triazine-exposed microalgae.

    PubMed

    Rioboo, C; Prado, R; Herrero, C; Cid, A

    2007-08-01

    Few data exist on potential toxic effects that pollutants may have on zooplankton fed microalgae exposed to pesticides. For that reason, microalgal cultures were exposed to different concentrations of the triazine herbicide terbutryn, and used as exclusive food source to Brachionus sp. females, with the aim to evaluate potential deleterious effects upon population growth, survival, reproduction and feeding of the rotifer. Chlorella vulgaris cells were able to accumulate terbutryn, removing more than 90% of the total amount of herbicide in all the exposed cultures. Growth curves of Brachionus sp. showed that population density decreased as terbutryn concentration increased in the microalgal cells. In fact, this species of rotifer did not survive beyond four days when fed with microalgae exposed to 500 nM terbutryn. Percentage of reproductive females in rotifer populations fed with terbutryn-exposed microalgae decreased significantly as herbicide concentration increased. In control cultures, reproductive females laid a maximum of three eggs per individual; whereas in 100 nM cultures, reproductive females laid only one egg per individual throughout the treatment period. Terbutryn accumulated in C. vulgaris provoked a decrease in the feeding rate of Brachionus sp. cultures fed with these microalgae with respect to control cultures. After this treatment period, all the rotifer populations, except those fed with 500 nM terbutryn-exposed microalgae, showed recovery patterns when they were returned to fresh medium containing herbicide-free microalga. Taking into account the results obtained, uptake of pesticides by phytoplankton can directly affect higher trophic levels. PMID:17553575

  13. Decadal trends of the upper ocean salinity in the tropical Indo-Pacific since mid-1990s

    NASA Astrophysics Data System (ADS)

    Du, Yan; Zhang, Yuhong; Feng, Ming; Wang, Tianyu; Zhang, Ningning; Wijffels, Susan

    2015-11-01

    A contrasting trend pattern of sea surface salinity (SSS) between the western tropical Pacific (WTP) and the southeastern tropical Indian Ocean (SETIO) is observed during 2004-2013, with significant salinity increase in the WTP and freshening in the SETIO. In this study, we show that increased precipitation around the Maritime Continent (MC), decreased precipitation in the western-central tropical Pacific, and ocean advection processes contribute to the salinity trends in the region. From a longer historical record, these salinity trends started in the mid-1990s, a few years before the Global Warming Hiatus from 1998 to present. The salinity trends are associated a strengthening trend of the Walker Circulation over the tropical Indo-Pacific, which have reversed the long-term salinity changes in the tropical Indo-Pacific as a consequence of global warming. Understanding decadal variations of SSS in the tropical Indo-Pacific will better inform on how the tropical hydrological cycle will be affected by the natural variability and a warming climate.

  14. Land-use change and carbon flux between 1970s and 1990s in central highlands of Chiapas, Mexico

    SciTech Connect

    Jong, B.H.J. de; Ramirez-Marcial, N.; Ochoa-Gaona, S.; Mendoza-Vega, J.; Gonzalez-Espinosa, M.; March-Mifsut, I.; Cairns, M.A.; Haggerty, P.K.

    1999-04-01

    The authors present results of a study in an intensively impacted and highly fragmented landscape in which they apply field-measured carbon (C) density values to land-use/land-cover (LU/LC) statistics to estimate the flux of C between terrestrial ecosystems and the atmosphere from the 1970s and 1990s. Carbon densities were assigned to common LU/LC classes on vegetation maps produced by Mexican governmental organizations and, by differencing areas and C pools, net C flux was calculated from the central highlands of Chiapas, Mexico, during a 16-year period. The total area of closed forests was reduced by half while degraded and fragmented forests expanded 56% and cultivated land and pasture areas increased by 8% and 30%, respectively. Total mean C densities ranged from a high of 504 tons C/ha in the oak and evergreen cloud forests class to a low of 147 tons C/ha in the pasture class. The differences in total C densities among the various LU/LC classes were due to changes in biomass while soil organic matter C remained similar. The authors estimate that a total of 19.99 {times} 10{sup 6} tons C were released to the atmosphere during the period of time covered by the study, equal to approximately 34% of the 1975 vegetation C pool. The Chiapas highlands, while comprising just 0.3% of Mexico`s surface area, contributed 3% of the net national C emissions.

  15. Partners in Freedom: Contributions of the Langley Research Center to U.S. Military Aircraft of the 1990's

    NASA Technical Reports Server (NTRS)

    Chambers, Joseph R.

    2000-01-01

    Established in 1917 as the nation#s first civil aeronautics research laboratory under the National Advisory Commit-tee for Aeronautics (NACA), Langley was a small laboratory that solved the problems of flight for military and civil aviation. Throughout history, Langley has maintained a working partnership with the Department of Defense, U.S. industry, universities, and other government agencies to support the defense of the nation with research. During World War II, Langley directed virtually all of its workforce and facilities to research for military aircraft. Following the war, a balanced program of military and civil projects was undertaken. In some instances Langley research from one aircraft program helped solve a problem in another. At the conclusion of some programs, Langley obtained the research models for additional tests to learn more about previously unknown phenomena. The data also proved useful in later developmental programs. Many of the military aircraft in the U.S. inventory as of late 1999 were over 20 years old. Langley activities that contributed to the development of some of these aircraft began over 50 years prior. This publication documents the role, from early concept stages to problem solving for fleet aircraft, that Langley played in the military aircraft fleet of the United States for the 1990's.

  16. Impact of local sea surface temperature on changes of summer precipitation components over Northeast Asia in mid-1990s

    NASA Astrophysics Data System (ADS)

    Chang, Eun-Chul; Yeh, Sang-Wook; Yoshimura, Kei

    2014-05-01

    In this study, the new global atmospheric analysis dataset (DA126) which is produced by the global and regional integrated model system (GRIMs) global model program (GMP) is used to identify changes of the summer precipitation components in mid-1990s over Northeast Asia. The convective rain ratio (CRR) is used as the index to find changes of the precipitation component, which is the proportion of convective precipitation to the total precipitation. The CRR shows increasing trend over Northeast Asia where includes the Korea-Japan region for recent 30-years, whereas precipitation anomaly does not have a distinct trend over this region. The increased CRR shows a significant relationship with the increased local sea surface temperature (SST) variability. To investigate effects of the local SST on the summer precipitation components over Northeast Asia, two experiments are performed by utilizing the GRIMs regional model program (RMP). The CNTL experiment is forced by the observed SST whereas the CLIM run is forced by the climatological SST. Lateral boundary condition for two regional model experiments is provided by the GRIMs GMP run forced by the historical SSTs over tropical region to exclude mid-latitude SST effect. The SST warming increases the convective precipitation through the increased convective available potential energy and does not have large effects on the large-scale rainfall component. Consequently, the total amount of the precipitation and the CRR are increased by the local SST warming over Northeast Asia.

  17. Decadal trends of the upper ocean salinity in the tropical Indo-Pacific since mid-1990s

    PubMed Central

    Du, Yan; Zhang, Yuhong; Feng, Ming; Wang, Tianyu; Zhang, Ningning; Wijffels, Susan

    2015-01-01

    A contrasting trend pattern of sea surface salinity (SSS) between the western tropical Pacific (WTP) and the southeastern tropical Indian Ocean (SETIO) is observed during 2004–2013, with significant salinity increase in the WTP and freshening in the SETIO. In this study, we show that increased precipitation around the Maritime Continent (MC), decreased precipitation in the western-central tropical Pacific, and ocean advection processes contribute to the salinity trends in the region. From a longer historical record, these salinity trends started in the mid-1990s, a few years before the Global Warming Hiatus from 1998 to present. The salinity trends are associated a strengthening trend of the Walker Circulation over the tropical Indo-Pacific, which have reversed the long-term salinity changes in the tropical Indo-Pacific as a consequence of global warming. Understanding decadal variations of SSS in the tropical Indo-Pacific will better inform on how the tropical hydrological cycle will be affected by the natural variability and a warming climate. PMID:26522168

  18. Tropical forests were the primary sources of new agricultural land in the 1980s and 1990s

    PubMed Central

    Gibbs, H. K.; Ruesch, A. S.; Achard, F.; Clayton, M. K.; Holmgren, P.; Ramankutty, N.; Foley, J. A.

    2010-01-01

    Global demand for agricultural products such as food, feed, and fuel is now a major driver of cropland and pasture expansion across much of the developing world. Whether these new agricultural lands replace forests, degraded forests, or grasslands greatly influences the environmental consequences of expansion. Although the general pattern is known, there still is no definitive quantification of these land-cover changes. Here we analyze the rich, pan-tropical database of classified Landsat scenes created by the Food and Agricultural Organization of the United Nations to examine pathways of agricultural expansion across the major tropical forest regions in the 1980s and 1990s and use this information to highlight the future land conversions that probably will be needed to meet mounting demand for agricultural products. Across the tropics, we find that between 1980 and 2000 more than 55% of new agricultural land came at the expense of intact forests, and another 28% came from disturbed forests. This study underscores the potential consequences of unabated agricultural expansion for forest conservation and carbon emissions. PMID:20807750

  19. Decadal trends of the upper ocean salinity in the tropical Indo-Pacific since mid-1990s.

    PubMed

    Du, Yan; Zhang, Yuhong; Feng, Ming; Wang, Tianyu; Zhang, Ningning; Wijffels, Susan

    2015-01-01

    A contrasting trend pattern of sea surface salinity (SSS) between the western tropical Pacific (WTP) and the southeastern tropical Indian Ocean (SETIO) is observed during 2004-2013, with significant salinity increase in the WTP and freshening in the SETIO. In this study, we show that increased precipitation around the Maritime Continent (MC), decreased precipitation in the western-central tropical Pacific, and ocean advection processes contribute to the salinity trends in the region. From a longer historical record, these salinity trends started in the mid-1990s, a few years before the Global Warming Hiatus from 1998 to present. The salinity trends are associated a strengthening trend of the Walker Circulation over the tropical Indo-Pacific, which have reversed the long-term salinity changes in the tropical Indo-Pacific as a consequence of global warming. Understanding decadal variations of SSS in the tropical Indo-Pacific will better inform on how the tropical hydrological cycle will be affected by the natural variability and a warming climate. PMID:26522168

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

    USGS Publications Warehouse

    Beissenger, S.R.; Wunderle, J.M., Jr.; 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

  1. Effects of Sample Size on Estimates of Population Growth Rates Calculated with Matrix Models

    PubMed Central

    Fiske, Ian J.; Bruna, Emilio M.; Bolker, Benjamin M.

    2008-01-01

    Background Matrix models are widely used to study the dynamics and demography of populations. An important but overlooked issue is how the number of individuals sampled influences estimates of the population growth rate (λ) calculated with matrix models. Even unbiased estimates of vital rates do not ensure unbiased estimates of λ–Jensen's Inequality implies that even when the estimates of the vital rates are accurate, small sample sizes lead to biased estimates of λ due to increased sampling variance. We investigated if sampling variability and the distribution of sampling effort among size classes lead to biases in estimates of λ. Methodology/Principal Findings Using data from a long-term field study of plant demography, we simulated the effects of sampling variance by drawing vital rates and calculating λ for increasingly larger populations drawn from a total population of 3842 plants. We then compared these estimates of λ with those based on the entire population and calculated the resulting bias. Finally, we conducted a review of the literature to determine the sample sizes typically used when parameterizing matrix models used to study plant demography. Conclusions/Significance We found significant bias at small sample sizes when survival was low (survival = 0.5), and that sampling with a more-realistic inverse J-shaped population structure exacerbated this bias. However our simulations also demonstrate that these biases rapidly become negligible with increasing sample sizes or as survival increases. For many of the sample sizes used in demographic studies, matrix models are probably robust to the biases resulting from sampling variance of vital rates. However, this conclusion may depend on the structure of populations or the distribution of sampling effort in ways that are unexplored. We suggest more intensive sampling of populations when individual survival is low and greater sampling of stages with high elasticities. PMID:18769483

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

    NASA Astrophysics Data System (ADS)

    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

  3. The impacts of lower population growth on the quality of life and economic development: China's experience.

    PubMed

    Jiang, Z; Zhang, L

    1994-02-01

    China's population in 1993 was 1.18 billion, which makes it the most populous nation in the world. The Chinese population policy aims to control growth and improve the quality of human resources. Most Chinese recognize the need for family planning. Replacement level fertility has been achieved, because there are limited resources to support a large population. Scarce resources are limiting economic development. There has been a loss of arable land, and the dream of 2 hectares of land, a cow, a wife and children, and a comfortable bed are not attainable. Water resources are also limited, the ratio of water to arable land is unevenly balanced, and there is overdrawing of groundwater. Energy shortages, environmental pollution, and pressure on employment are other effects of population pressure. The surplus labor force is about 150-190 million farmering laborers. Labor productivity has declined due to excess labor. Projections are that 20-25% of employees are surplus, and unemployed in urban areas will total 10 million. Without a strong family planning program, there will be a rural labor surplus of 200-360 million people by the year 2000. One benefit of lower population growth is the savings in child-rearing expenses. Estimated births averted between 1971 and 1992 was about 250 million, which translates to a savings of $500 billion. About 66% of this sum would be recovered in the same period and 33% would be recovered between 1993-2007. Government and nongovernmental spending on family planning totaled an estimated $10 billion between 1971-92. The ratio of input to output for averted births is 1 to 17. Total spending would have been RMB 2500 billion yuan for child rearing of averted births between 1971-92 and RMB 1828 billion yuan between 1991-2005. The saved money could be invested in economic development. An estimated 10% of national income could be saved. Another benefit from low population growth is the increased consumption evident between 1971-90. There has not

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

    PubMed

    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

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

    PubMed

    Rhein, E

    1994-08-25

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

  6. Field population abundance of leafhopper (Homoptera: Cicadelidae) and planthopper (Homoptera: Delphacidae) as affected by rice growth stages

    NASA Astrophysics Data System (ADS)

    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 (p<0.05). Delphacidae was most abundance during maturing stages, while the abundance of Cicadelidae peaked during reproductive stage of rice growth. Differences in temporal abundance of the population of these two homopterans indicated adaptive feeding strategy to reduce food competition.

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

    PubMed

    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. PMID:25589079

  8. Collective Bargaining in Higher Education: The 1990's. Proceedings of the Annual Conference (18th, New York, New York, April 23-24, 1990).

    ERIC Educational Resources Information Center

    Douglas, Joel M., Ed.

    This report of proceedings provides transcripts of 14 speeches concerning collective bargaining in higher education. Conference themes were: unionized employment relations; and the economic, political, and legal issues of the 1990s that are viewed as being influential in the collective bargaining process. The speeches are as follows: "Union…

  9. Influence of climate regime shift on the interdecadal change in tropical cyclone activity over the Pacific Basin during the middle to late 1990s

    NASA Astrophysics Data System (ADS)

    Hong, Chi-Cherng; Wu, Yi-Kai; Li, Tim

    2016-01-01

    In this study, a new interpretation is proposed for the abrupt decrease in tropical cyclone (TC) activity in the western North Pacific (WNP) after the late 1990s. We hypothesize that this abrupt change constitutes a part of the phenomenon of interdecadal change in TC activity in the Pacific Basin, including the WNP, western South Pacific (WSP), and eastern North Pacific. Our analysis revealed that the climate-regime shift (CRS) in the Pacific during the middle to late 1990s resulted in a La Niña-like mean state, which was responsible for the interdecadal change in TC activity in the late 1990s. Analyses of the TC genesis potential index and numerical experiments revealed that the decline in TC activity in both the WNP and WSP was primarily attributable to the increase of vertical wind shear in the central Pacific due to the La Niña-like associated cold sea surface temperature (SST). Conversely, the La Niña-like associated warm SST in the western Pacific produced anomalous vertical transport of water vapor, increasing moisture levels in the mid-troposphere and TC activity in the western WNP. Furthermore, the CRS modified the mean TC genesis position and shifted the steering flow to the west, resulting in the increased frequency of TC landfalls in Taiwan, southeastern China, and northern Australia after the late 1990s.

  10. Educating for Location? The Policy Context of "Becoming Asia-Literate" in Five Western Countries/Regions in the 1990s

    ERIC Educational Resources Information Center

    Pang, David

    2005-01-01

    This article examines the educational policy responses by five western countries/regions to the "Asian economic miracle" in the 1990s. It begins by stating that the idea of the global economic context has assumed considerable importance in the current educational thinking and debates. It then shows that Asia has been thematized in the west as a…

  11. The Top Ten Judicial Decisions Affecting Labor Relations in Public Education during the Decade of the 1990's: The Verdict of Quiescent Years.

    ERIC Educational Resources Information Center

    Ruben, Alan Miles

    2001-01-01

    The author discusses what he considers to be the 10 leading cases on education labor relations decided in state and federal courts during the 1990s. Concludes with a prediction that efforts to implement merit-pay schemes tied to student performance will lead to employment conflict. (PKP)

  12. Comparing the Understanding of the Nature of Science by Preservice Secondary Science Teachers in the Mid-1960s and the Early 1990s.

    ERIC Educational Resources Information Center

    Boone, William J.; Andersen, Hans O.

    1996-01-01

    Presents a study comparing the understanding of the nature of science by preservice secondary science teachers in the mid-1960s and the early 1990s. Uses the Nature of Science Scale (NOSS) to determine teachers' understanding. Concludes with an evaluation of most items for which the responses changed dramatically in those 25 years. Contains 19…

  13. Higher Education Reform in the 1990s. Minutes of the Meeting of the Association of Research Libraries (116th, New Orleans, Louisiana, May 9-11, 1990).

    ERIC Educational Resources Information Center

    Bixby, Pamela, Ed.

    This membership meeting focused on higher education reform in the 1990s and the mission of educational institutions in the face of changes in educational philosophy, cultural and demographic changes, and shifts in public policy. It is argued that the ongoing academic revolution will define higher education in the next decade, and that research…

  14. Children and Development in the 1990s: A UNICEF Sourcebook on the Occasion of the World Summit for Children (New York, New York, September 20-30, 1990).

    ERIC Educational Resources Information Center

    United Nations Children's Fund, New York, NY.

    This eight-part sourcebook provides background information, data, and references relating to child welfare issues throughout the world. The book is organized around a set of goals for children in the 1990s. An introductory section provides an overview of these goals and strategies for achieving them, and discusses infant and child mortality,…

  15. A Descriptive Analysis of Race/Ethnicity and Sex of Individuals Appearing on the Covers of "Sports Illustrated" in the 1990s

    ERIC Educational Resources Information Center

    Lumpkin, Angela

    2007-01-01

    The purpose of this study was to examine whether the number of individuals pictured on the covers of Sports Illustrated during the 1990s was reflective of their levels of participation by sport, race/ethnicity, and sex. These descriptors of the individuals pictured on each cover between 1990 and 1999 were identified and analyzed. African Americans…

  16. The Effect of Local Labor Market Conditions in the 1990s on the Likelihood of Community College Students' Persistence and Attainment

    ERIC Educational Resources Information Center

    Kienzl, Gregory S.; Alfonso, Mariana; Melguizo, Tatiana

    2007-01-01

    This study analyzes the influence of local labor market conditions on the year-to-year persistence and attainment decisions of a sample of traditional-aged students who attended community colleges during the 1990s. The findings suggest that the enrollment and attainment decisions of these first-time community college students were not made purely…

  17. Higher Education into the 1990s: New Dimensions. To Commemorate the Jubilee of the Society for Research into Higher Education, 1964-1989.

    ERIC Educational Resources Information Center

    Ball, Christopher, Ed.; Eggins, Heather, Ed.

    This collection of essays aims to contribute to the understanding of the present predicament and future potential of higher education in the United Kingdom. It considers the new dimensions being introduced into higher education which are likely to have marked effects in the 1990s. It explores the tensions between the past and future, tradition and…

  18. Pathbreaking CBO Study Shows Dramatic Increases in Income Disparities in 1980s and 1990s: An Analysis of the CBO Data. Revised.

    ERIC Educational Resources Information Center

    Shapiro, Isaac; Greenstein, Robert; Primus, Wendell

    A study by the Congressional Budget Office of income and tax trends since 1979 showed dramatic increases in income disparities, especially between the wealthiest one percent of Americans and the rest of society, in the 1980s and 1990s. The percentage of income Americans paid in federal taxes declined for every income group between 1979-97. The…

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

    USGS Publications Warehouse

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

    2015-01-01

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

  20. Examining Perceptions of Rapid Population Growth in North and South Gondar Zones, Northwest Ethiopia

    PubMed Central

    Worku, Alemayehu

    2009-01-01

    Ethiopia is one of the most populous countries in Africa and ranks second only to Nigeria. Rapid population growth has hampered the country's development, making the eradication of extreme poverty and hunger difficult. This study which had two components—quantitative and qualitative—was aimed at exploring the perceptions of women and other social groups on the prevailing population pressures. The quantitative study involved 3,512 women aged 15–49 years. The qualitative study consisted of five focus-group discussions and six key-informant interviews. Over 90% of women (n=3,512) who participated in the quantitative study and nearly all the focus-group discussants and interviewees (n=39) felt that something should be done to keep the population from growing too fast. Most (over 90%) participants approved of the Government passing a law regarding the maximum number of children that a couple should have. It is, therefore, timely for the responsible bodies to exert maximum effort and commitment in responding to the emerging attitudes of the people by making the population problem a priority. PMID:20099762

  1. Biomass, growth, and development of populations of herbivorous zooplankton in the southeastern Bering Sea during spring

    SciTech Connect

    Vidal, J.; Smith, S.L.

    1985-09-01

    Two distinct communities of herbivorous zooplankton, separated by an oceanographic front, inhabit the continental shelf and slope of the southeastern Bering Sea during spring. The community over the outer shelf and slope is dominated by populations of large-sized oceanic copepods (mainly Neocalanus ssp.) that develop early in spring and attain maximum biomass and growth rates by mid- to late spring. Total biomass and growth rates of herbivores follow the spring outburst of phytoplankton; during April and May biomass increases from less than or equal to1 to approx.14 g C m/sup -2/ on the slope and to approx.10 g C m/sup -2/ on the outer shelf, and maximum growth rates >500 and approx.300 mg C m/sup -2/ day/sup -1/ occure on the slope and outer shelf, respectively in May. The dominant species, N. plumchrus, grows from copepodid I and V between late March and early May, and after attaining maximum body weight in late May and early June it begins its downward migration. The inshore community on the middle shelf is dominated by the euphausiid Thysanoessa raschi in April and May and by the copepod Calanus marshallae in late May and early June. Total biomass (less than or equal to g C m/sup -2/) and growth rates (less than or equal to50 mg C m/sup -2/) of the inshore community are substantially lower than those of the offshore community and show a delayed response to the spring bloom of phytoplankton; both biomass and growth rates increase about one month after the bloom. Small herbivorous copepods contributed little to the total biomass and growth rates of either community and the cumulative community growth rates during April and May decreases from 18.3 g C m/sup -2/ on the slope to 2.5 g C m/sup -2/ on the middle shelf. 79 refs., 15 figs., 7 tabs.

  2. National Health Expenditure Growth in the 1980's: An Aging Population, New Technologies, and Increasing Competition

    PubMed Central

    Freeland, Mark S.; Schendler, Carol Ellen

    1983-01-01

    Health care spending in the United States more than tripled between 1971 and 1981, increasing from $83 billion to $287 billion. This growth in health sector spending substantially outpaced overall growth in the economy, averaging 13.2 percent per year compared to 10.5 percent for the gross national product (GNP). By 1981, one out of every ten dollars of GNP was spent on health care, compared to one out of every thirteen dollars of GNP in 1971. If current trends continue and if present health care financing arrangements remain basically unchanged, national health expenditures are projected to reach approximately $756 billion in 1990 and consume roughly 12 percent of GNP. The focal issue in health care today is cost and cost Increases. The outlook for the 1980's is for continued rapid growth but at a diminished rate. The primary force behind this moderating growth is projected lower inflation. However, real growth rates are also expected to moderate slightly. The chief factors influencing the growth of health expenditures in the eighties are expected to be aging of the population, new medical technologies, increasing competition, restrained public funding, growth in real income, increased health manpower, and a deceleration in economy-wide inflation. Managers, policy makers and providers in the health sector, as in all sectors, must include in today's decisions probable future trends. Inflation, economic shocks, and unanticipated outcomes of policies over the last decade have intensified the need for periodic assessments of individual industries and their relationship to the macro economy. This article provides such an assessment for the health care industry. Baseline current-law projections of national health expenditures are made to 1990. PMID:10309852

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

    PubMed

    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. PMID:14713050

  4. In the grips of growth.

    PubMed

    Sherman, D

    1992-04-01

    Rapid population growth and increasing environmental degradation threaten the likelihood of a better life for citizens in the US and those in developing countries in the future. To achieve sustainable development, population cannot continue to grow (possible 3-fold increase during the 20th century) since it only burdens the earth and future generations with more and more pollution, waste, and resource depletion. Warning signs already exist: global warming, ozone depletion, vanishing species, and deforestations. Future projections for population growth highlight the problem of employment, unemployment, and underemployment, and underemployment in the US and even more so in developing countries where they are already of great concern. The US population is growing faster than any other developed nation. Yet many economists believe that population growth equated a healthy economy and environmental degradation is necessary for progress. The Workforce 2000 report prepared by conservative think tank contends that even though unemployment increases steadily, the US will soon face a shortage of workers. The report used misleading data and false assumptions, however. For example, it shows the work force growing at 1%/year in the 1990s compared with 3% in the 1970s, but the higher growth in the 1970s was due to the maturing of the baby boomers. Other economists note that in a stable population, fewer people compete for jobs which increases wages and thus the standard of living for most people. Communities can monitor local food, water, and energy supplies, jobs, and health care in a stable population. Company worries about labor shortages are really worries about shortages of cheap labor, consequently many companies are moving factories outside the US where they can employ cheap labor. An economist who favors self-reliance notes that the US population policy is to let population take its natural course, which is antiquated thinking. PMID:12285221

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

    Identifying the mechanisms that create and maintain biodiversity is a central challenge in biology. Stable diversification of microbial populations often requires the evolution of differences in resource utilization. Alternatively, coexistence can be maintained by specialization to exploit spatial heterogeneity in the environment. Here, we report spontaneous diversification maintained by a related but distinct mechanism: crowding avoidance. During experimental evolution of laboratory Saccharomyces cerevisiae populations, we observed the repeated appearance of “adherent” (A) lineages able to grow as a dispersed film, in contrast to their crowded “bottom-dweller” (B) ancestors. These two types stably coexist because dispersal reduces interference competition for nutrients among kin, at the cost of a slower maximum growth rate. This tradeoff causes the frequencies of the two types to oscillate around equilibrium over the course of repeated cycles of growth, crowding, and dispersal. However, further coevolution of the A and B types can perturb and eventually destroy their coexistence over longer time scales. We introduce a simple mathematical model of this “semistable” coexistence, which explains the interplay between ecological and evolutionary dynamics. Because crowded growth generally limits nutrient access in biofilms, the mechanism we report here may be broadly important in maintaining diversity in these natural environments. PMID:26240355

  7. Dynamical consequences of adaptation of the growth rates in a system of three competing populations

    NASA Astrophysics Data System (ADS)

    Dimitrova, Zlatinka I.; Vitanov, Nikolay K.

    2001-09-01

    We investigate the nonlinear dynamics of a system of populations competing for the same limited resource for the case where each of the populations adapts its growth rate to the total number of individuals in all populations. We consider regions of parameter space where chaotic motion of the Shilnikov kind exists and present results for two characteristic values of the growth ratio adaptation factor r*: r* = -0.15 and 5. Negative r* can lead to vanishing of regions of chaotic motion and to a stabilization of a fixed point of the studied model system of differential equations. Positive r* lead to changes of the shape of the bifurcation diagrams in comparison with the bifurcation diagrams for the case without adaptation. For the case r* = 5 we observe transition to chaos by period-doubling bifurcations, windows of periodic motion between the regions of chaotic motion and a region of transient chaos after the last window of periodic motion. The Lyapunov dimension for the chaotic attractors is close to two and the Lyapunov spectrum has a structure which allows a topological analysis of the attractors of the investigated system.

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

    PubMed Central

    Taylor, Marylee C.; Schroeder, Matthew B.

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Interdecadal change of the controlling mechanisms for East Asian early summer rainfall variation around the mid-1990s

    NASA Astrophysics Data System (ADS)

    Yim, So-Young; Wang, Bin; Kwon, MinHo

    2013-04-01

    East Asian (EA) summer monsoon shows considerable differences in the mean state and principal modes of interannual variation between early summer (May-June, MJ) and late summer (July-August, JA). The present study focuses on the early summer (MJ) precipitation variability. We find that the interannual variation of the MJ precipitation and the processes controlling the variation have been changed abruptly around the mid-1990s. The rainfall anomaly represented by the leading empirical orthogonal function has changed from a dipole-like pattern in pre-95 epoch (1979-1994) to a tripole-like pattern in post-95 epoch (1995-2010); the prevailing period of the corresponding principal component has also changed from 3-5 to 2-3 years. These changes are concurrent with the changes of the corresponding El Nino-Southern Oscillation (ENSO) evolutions. During the pre-95 epoch, the MJ EA rainfall anomaly is coupled to a slow decay of canonical ENSO events signified by an eastern Pacific warming, which induces a dipole rainfall feature over EA. On the other hand, during the post-95 epoch the anomalous MJ EA rainfall is significantly linked to a rapid decay of a central Pacific warming and a distinct tripolar sea surface temperature (SST) in North Atlantic. The central Pacific warming-induced Philippine Sea anticyclone induces an increased rainfall in southern China and decreased rainfall in central eastern China. The North Atlantic Oscillation-related tripolar North Atlantic SST anomaly induces a wave train that is responsible for the increase northern EA rainfall. Those two impacts form the tripole-like rainfall pattern over EA. Understanding such changes is important for improving seasonal to decadal predictions and long-term climate change in EA.

  11. Interdecadal change of the controlling mechanisms for East Asian early summer rainfall variation around the mid-1990s

    NASA Astrophysics Data System (ADS)

    Yim, So-Young; Wang, Bin; Kwon, MinHo

    2014-03-01

    East Asian (EA) summer monsoon shows considerable differences in the mean state and principal modes of interannual variation between early summer (May-June, MJ) and late summer (July-August, JA). The present study focuses on the early summer (MJ) precipitation variability. We find that the interannual variation of the MJ precipitation and the processes controlling the variation have been changed abruptly around the mid-1990s. The rainfall anomaly represented by the leading empirical orthogonal function has changed from a dipole-like pattern in pre-95 epoch (1979-1994) to a tripole-like pattern in post-95 epoch (1995-2010); the prevailing period of the corresponding principal component has also changed from 3-5 to 2-3 years. These changes are concurrent with the changes of the corresponding El Nino-Southern Oscillation (ENSO) evolutions. During the pre-95 epoch, the MJ EA rainfall anomaly is coupled to a slow decay of canonical ENSO events signified by an eastern Pacific warming, which induces a dipole rainfall feature over EA. On the other hand, during the post-95 epoch the anomalous MJ EA rainfall is significantly linked to a rapid decay of a central Pacific warming and a distinct tripolar sea surface temperature (SST) in North Atlantic. The central Pacific warming-induced Philippine Sea anticyclone induces an increased rainfall in southern China and decreased rainfall in central eastern China. The North Atlantic Oscillation-related tripolar North Atlantic SST anomaly induces a wave train that is responsible for the increase northern EA rainfall. Those two impacts form the tripole-like rainfall pattern over EA. Understanding such changes is important for improving seasonal to decadal predictions and long-term climate change in EA.

  12. Can we reconcile differences in estimates of carbon fluxes from land-use change and forestry for the 1990s?

    NASA Astrophysics Data System (ADS)

    Ito, A.; Penner, J. E.; Prather, M. J.; de Campos, C. P.; Houghton, R. A.; Kato, T.; Jain, A. K.; Yang, X.; Hurtt, G. C.; Frolking, S.; Fearon, M. G.; Chini, L. P.; Wang, A.; Price, D. T.

    2008-02-01

    The effect of Land Use Change and Forestry (LUCF) on terrestrial carbon fluxes can be regarded as a carbon credit or debit under the UNFCCC, but scientific uncertainty in the estimates for LUCF remains large. Here, we assess the LUCF estimates by examining a variety of models of different types with different land cover change maps in the 1990s. Annual carbon pools and their changes are separated into different components for separate geographical regions, while annual land cover change areas and carbon fluxes are disaggregated into different LUCF activities and the biospheric response due to CO2 fertilization and climate change. We developed a consolidated estimate of the terrestrial carbon fluxes that combines book-keeping models with process-based biogeochemical models and inventory estimates and yields an estimate of the global terrestrial carbon flux that is within the uncertainty range developed in the IPCC 4th Assessment Report. We examined the USA and Brazil as case studies in order to assess the cause of differences from the UNFCCC reported carbon fluxes. Major differences in the litter and soil organic matter components are found for the USA. Differences in Brazil result from assumptions about the LUC for agricultural purposes. The effects of CO2 fertilization and climate change also vary significantly in Brazil. Our consolidated estimate shows that the small sink in Latin America is within the uncertainty range from inverse models, but that the sink in the USA is significantly smaller than the inverse models estimates. Because there are different sources of errors at the country level, there is no easy reconciliation of different estimates of carbon fluxes at the global level. Clearly, further work is required to develop data sets for historical land cover change areas and models of biogeochemical changes for an accurate representation of carbon uptake or emissions due to LUC.

  13. Can we reconcile differences in estimates of carbon fluxes from land-use change and forestry for the 1990s?

    NASA Astrophysics Data System (ADS)

    Ito, A.; Penner, J. E.; Prather, M. J.; de Campos, C. P.; Houghton, R. A.; Kato, T.; Jain, A. K.; Yang, X.; Hurtt, G. C.; Frolking, S.; Fearon, M. G.; Chini, L. P.; Wang, A.; Price, D. T.

    2008-06-01

    The effect of Land Use Change and Forestry (LUCF) on terrestrial carbon fluxes can be regarded as a carbon credit or debit under the UNFCCC, but scientific uncertainty in the estimates for LUCF remains large. Here, we assess the LUCF estimates by examining a variety of models of different types with different land cover change maps in the 1990s. Annual carbon pools and their changes are separated into different components for separate geographical regions, while annual land cover change areas and carbon fluxes are disaggregated into different LUCF activities and the biospheric response due to CO2 fertilization and climate change. We developed a consolidated estimate of the terrestrial carbon fluxes that combines book-keeping models with process-based biogeochemical models and inventory estimates and yields an estimate of the global terrestrial carbon flux that is within the uncertainty range developed in the IPCC 4th Assessment Report. We examined the USA and Brazil as case studies in order to assess the cause of differences from the UNFCCC reported carbon fluxes. Major differences in the litter and soil organic matter components are found for the USA. Differences in Brazil result from assumptions about the LUC for agricultural purposes. The effects of CO2 fertilization and climate change also vary significantly in Brazil. Our consolidated estimate shows that the small sink in Latin America is within the uncertainty range from inverse models, but that the sink in the USA is significantly smaller than the inverse models estimates. Because there are different sources of errors at the country level, there is no easy reconciliation of different estimates of carbon fluxes at the global level. Clearly, further work is required to develop data sets for historical land cover change areas and models of biogeochemical changes for an accurate representation of carbon uptake or emissions due to LUC.

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

    PubMed

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

    2011-12-01

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

  15. IKVAV regulates ERK1/2 and Akt signalling pathways in BMMSC population growth and proliferation

    PubMed Central

    Li, B; Qiu, T; Zhang, P; Wang, X; Yin, Y; Li, S

    2014-01-01

    Objectives The molecular mechanism of bone marrow mesenchymal stem cell (BMMSC) population growth and proliferation, induced by Isoleucyl-lysyl-valyl-alanyl-valine (IKVAV), was explored in this study. Materials and methods IKVAV peptides were synthesized by the solid-phase method. Influence of IKVAV on BMMSC population growth and proliferation were investigated by assays of CCK-8, flow cytometry, real-time PCR and western blotting. Results IKVAV peptide was found to induce proliferation and proliferating cell nuclear antigen (PCNA) synthesis of BMMSC in a dose- and time-dependent manner. Cell cycle analysis showed that the proportion of IKVAV-treated BMMSC in S phase in was higher than controls. Western blot results suggested that mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) and phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signalling pathways were activated by IKVAV by enhancing phosphorylation levels of ERK1/2 and Akt in the BMMSCs. Meanwhile, phosphorylation levels of ERK1/2 and Akt were partially blocked by ERK1/2 inhibitor (PD98059) and Akt inhibitor (wortmannin), respectively. Conclusions Our results demonstrated that IKVAV stimulated BMMSC population growth and proliferation by activating MAPK/ERK1/2 and PI3K/Akt signalling pathways. This study is the first to reveal an enhancement effect of IKVAV peptide on BMMSC at the signal transduction level, and the outcome could provide experimental evidence for application of IKVAV-grafted scaffolds in the field of BMMSC-based tissue engineering. PMID:24617901

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

    PubMed Central

    Russell, Tanya L.; Lwetoijera, Dickson W.; Knols, Bart G. J.; Takken, Willem; Killeen, Gerry F.; Ferguson, Heather 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 phenotypic traits predict the dynamics of Anopheles gambiae sensu lato mosquitoes, the most important vectors of human malaria. Anopheles gambiae dynamics were monitored over a six-month period of seasonal growth and decline. The population exhibited density-dependent feedback, with the carrying capacity being modified by rainfall (97% wAICc support). The individual phenotypic expression of the maternal (p = 0.0001) and current (p = 0.040) body size positively influenced population growth. Our field-based evidence uniquely demonstrates that individual fitness can have population-level impacts and, furthermore, can mitigate the impact of exogenous drivers (e.g. rainfall) in species whose reproduction depends upon it. Once frontline interventions have suppressed mosquito densities, attempts to eliminate malaria with supplementary vector control tools may be attenuated by increased population growth and individual fitness. PMID:21389034

  17. Genetic analysis of bone quality traits and growth in a random mating broiler population.

    PubMed

    González-Cerón, F; Rekaya, R; Aggrey, S E

    2015-05-01

    We report the genetic relationship between growth and bone quality traits in a random mating broiler control population. Traits studied were growth rates from week 0 to 4 [body weight gain (BWG) 0 to 4], from week 0 to 6 (BWG 0 to 6), and residual feed intake (RFI) from week 5 to 6 (RFI 5 to 6). Bone quality traits were obtained at 6 weeks of age. These traits were shank weight (SW), shank length (SL), shank diameter (SDIAM), tibia weight (TW), tibia length (TL), and tibia diameter (TDIAM). Likewise, tibia was used to obtain the tibia density (TDEN), tibia breaking strength (TBS), tibia mineral density (TMD), tibia mineral content (TMC), and tibia ash content (TAC). At the phenotypic level, growth traits were positively correlated with most of the bone quality traits except with TDEN and TAC which tended to show unfavorable associations (-0.04 to -0.31). Heritability of bone quality traits ranged from 0.08 to 0.54. The additive genetic associations of growth traits with weight, length, and diameter of shank and tibia were positive (0.37 to 0.80). A similar pattern was observed with TMD and TMC (0.06 to 0.65). In contrast, growth traits showed unfavorable genetic associations with TDEN, TBS, and TAC (-0.03 to -0.18). It was concluded that bone quality traits have an additive genetic background and they can be improved by means of genetic tools. It appears that selection for growth is negatively correlated with some traits involved in the integrity, health, and maturity of leg bones. PMID:25784765

  18. Optimal policies aimed at stabilization of populations with logistic growth under human intervention.

    PubMed

    Cruz-Rivera, Erica; Vasilieva, Olga

    2013-02-01

    This work examines both positive and negative impacts that economic growth may have on the ecological dynamics and stability of a single biological species. Local extinction of the species may force the social planner to implement defensive expenditures aimed at conservation of the species population by means of habitat protection. The latter may lead to an ecological equilibrium that will be different from the natural equilibrium that would have arisen in the absence of human intervention. Moreover, the existence of such equilibrium is formally demonstrated and its stability properties are revised. Additionally, optimal-choice decision policies are constructed on the basis of Pontryagin's maximum principle. Under such policies together with initial abundance of the species, the growth trajectories will move the system towards the fixed point of maximum species abundance. PMID:22960017

  19. A single dividing cell population with imbalanced fate drives oesophageal tumour growth.

    PubMed

    Frede, Julia; Greulich, Philip; Nagy, Tibor; Simons, Benjamin D; Jones, Philip H

    2016-09-01

    Understanding the cellular mechanisms of tumour growth is key for designing rational anticancer treatment. Here we used genetic lineage tracing to quantify cell behaviour during neoplastic transformation in a model of oesophageal carcinogenesis. We found that cell behaviour was convergent across premalignant tumours, which contained a single proliferating cell population. The rate of cell division was not significantly different in the lesions and the surrounding epithelium. However, dividing tumour cells had a uniform, small bias in cell fate so that, on average, slightly more dividing than non-dividing daughter cells were generated at each round of cell division. In invasive cancers induced by Kras(G12D) expression, dividing cell fate became more strongly biased towards producing dividing over non-dividing cells in a subset of clones. These observations argue that agents that restore the balance of cell fate may prove effective in checking tumour growth, whereas those targeting cycling cells may show little selectivity. PMID:27548914

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

    PubMed Central

    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.

    2013-01-01

    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. PMID:23720545