Population density functions: a differential equation approach

"This paper introduces a new mathematical technique to describe population density functions. Two length scales, which characterize the variation of these density functions within a region, are identified. A differential equation is derived and asymptotic solutions obtained. Two specific techniques, the method of matched asymptotic expansions and the method of multiple scales, are introduced and illustrated by application to population densities at both the metropolitan and regional levels."     

Population,progress, and peanuts

Population and development, more specifically on matters relating to family planning, contraceptives and abortion, have always been key issues at the UN. These were the challenges faced by the Member States of the UN during the General Assembly held in New York from June 30 to July 2, 1999. The 1999 session covered a wide range of questions, which reflected universal consensus on concerns including adolescent reproduction and sexual health, as well as gender-related issues. The special meeting lasted for 3 days of visionary hopes and politics for the future of the world, and also took into account the crucial issue of resources and fundraising. The 1994 International Conference on Population and Development (ICPD) in Cairo was the starting point for such an international understanding and consensus. In the years following 1994, the challenge to carry out lessons learned from the Cairo Conference and ICPD has now led to a final document, which guides nations across the globe on where to concentrate key future actions.     

Gender,Environment and Population

Based on field research from three regions with distinct variations in environment, population density, livelihood bases and levels of resource dependency, this study investigates the gender aspects of environmental change. It seeks to illustrate the relevance of gender factors for the patterns of adaptation to change, for the welfare impact of changes on the population, and for the ramifications for resource management and livelihood generation at the community level. It employs a gender analysis to examine the impact of such changes on population variables, particularly on health and nutrition, and to explore the more general question of whether women's socio-economic status is being threatened by the pressures of environmental change.     

Chemistry,Population, Resources

Abstract

Chemistry plays a dominant role in the development of modern human societies over the entire globe. Improving the health and nutrition of people has led to a rapid growth in population, especially among the developing nation. Increase in energy supplies has not matched population growth and, arguably, our total stock of accumulated energy capital is diminishing rapidly. The use of coal or nuclear fuels, instead of oil would present their own set of problems. There is however, the possibility of using sunshine directly, and thus living on our annual income of energy from the Sun. It would be possible, argue the following article, to grow hydrocarbon-producing plants in arid or semi-arid regions of the Earth where they would not compete with food production, and produce hydrocarbons at the order of $20.00 a barrel compared with the current crude oil price of $14.00 a barrel.     

Commuting, Migration, and Rural-Urban Population Dynamics

Over the past 25 years social scientists attempting to explain the dramatic changes in the relative distribution of urban and rural population growth have gravitated toward two competing explanations. The regional restructuring hypothesis holds that changes in the spatial distribution of employment opportunities have been dominant whereas the deconcentration hypothesis attributes these changes to changes in residential preferences of workers and consumers. We develop an empirical test of these two explanations based on whether commuting and migration are positively or negatively related after controlling for other economic factors. Our econometric results support the deconcentration hypothesis.     

Population density and the accuracy of the land valuations in the 1798 federal direct tax

Abstract

The peculiar operation of the 1798 federal direct tax has led scholars to question whether tax officials reported the land valuations from their districts faithfully. Peter Lindert and Jeffrey Williamson argue that southern tax assessors systemically under reported the value of southern real estate, and they adjust their income estimates to account for the likelihood of corruption. This paper affirms the reliability of the tax returns by demonstrating that population density, rather than corruption or lax enforcement, can explain nearly all of the variation between the assessment districts. Accepting the tax valuations as accurate would lower Lindert and Williamson’s income estimates, imply slower growth rate between 1774 and 1800, and suggest a higher growth rate between 1800 and 1850.     

Population density and development potential in rural Zimbabwe: an assessment based on the 1969 and 1982 censuses

"Based on 1969 and 1982 census data, this paper examines the spatial association between high rural population density and development potential in Zimbabwe and its significance for national development policy. A 1982 grid cell density map was compiled on the same geographical frame as an existing 1969 density map, yielding an intercensal density change map. A land classification map and a composite map of development constraints were rasterized on the same spatial framework and subjected to computer analysis. Areas of critically high (and generally increasing) densities showed strong spatial associations with areas of severe development constraints...."     

Population,light, and the size distribution of cities

We provide new insights on the city size distribution of countries around the world. Using more than 10,000 cities delineated via geospatial data and a globally consistent city identification scheme, we investigate distributional shapes in all countries. In terms of population, we find that Zipf's law holds for many, but not all, countries. Contrasting the distribution of population with the distribution of economic activity, measured by nighttime lights, across cities we shed light on the globally variant magnitude of agglomeration economies. Deviations from Zipf's law are to a large extent driven by an undue concentration in the largest cities. They benefit from agglomeration effects which seem to work through area rather than through density. Examining the cross‐country heterogeneity in the city size distribution, our model selection approach suggests that historical factors play an important role, in line with the time of development hypothesis.     

Carnivore competition, bone destruction, and bone density

In carnivore-modified archaeofaunal assemblages it is important to evaluate the degree to which carnivores have overprinted hominin behavioral signals. To examine the signals of increased competition for discarded bone, we present controlled experimental data on 33 simulated archaeological sites subjected to secondary consumption by spotted hyenas. We examine the relationship between competition, as measured by controlled numbers of hyenas and limb bones, and resultant levels of destruction and correlations between long-bone portion survivorship and bone density. Our results indicate that levels of destruction are equivalent regardless of the numbers of hyenas or long-bones included in the experimental assemblages. Correlations between long-bone epiphyseal and near-epiphyseal portions and bone density, however, do provide an indication of the level of competition. Results from the experimental study are used to highlight divergent levels of carnivore competition for hominin-discarded bone at the Plio-Pleistocene localities FLKN-Zinjanthropus and FLKN levels 1–2 from Olduvai Gorge, Tanzania.     

TID,electron density and ionospheric sounding

For the approximation of a parabolic ionospheric layer, the relation between the fluctuation amplitude of radio phase path in HF vertical sounding and sinusoidal disturbance parameters has been found. Horizontal disturbance propagation has not been considered. The determining factors are the relation of the vertical wavelength of the disturbance to the half-thickness of the layer and between operating and critical frequency.     

Tibetan,Population: Status Quo

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Population geography: disorder,death and future directions

This is one in a series of reports on research trends in population geography. The author suggests that recent political changes concerning the breakup of the former Soviet Union and a possible decline in concern among developed countries about the problems of developing ones should affect the research agenda. Particular attention is given to studies done on differential mortality and internal migration in developed countries.     

From Darkness into Light: Race,Population, and Environmental Advocacy

Environmentalists and environmental organizations in the USA have long identified population growth as a key threat to environmental sustainability at local and global scales. The neo‐Malthusian logics they invoke embed racialized images and categories in defining population “problems”, yet increasingly social justice language is invoked in population debates as a “solution” in the context of international development. This article explores the historical and contemporary characterizations of race as a central component of population–environment advocacy. It focuses on locations of race narratives in both the conceptualizations of population growth as an environmental problem, and family planning as a global solution. Through a critical analysis of the “population justice” framework, I argue that new discursive approaches attempt to reposition population work as socially just, while eliding critical analyses of race.