[Java's large population: two centuries of explanations]

"Explanation of demographic imbalance between Java and the socalled 'Outer-Islands' has been numerous for almost two centuries. Authors generally considered that the great density of population was a direct consequence of the high fertility of Javanese soils. Some of them, however, connected it with an early economical 'take-off'. But none of these analyses can explain why marginally suitable regions from an agricultural point of view were overcrowded especially when their economical development was low. We propose another explanation scheme on an historical basis." (SUMMARY IN ENG)

Urbanization and childhood leukaemia in Taiwan

BACKGROUND

In the 1980s socioeconomic development was dramatically rapid in the urbanized municipalities of Taiwan due to a prospering economy. This study addressed the question: Could differences in the incidence of childhood leukaemia (age <15) be demonstrated between urban and rural communities in Taiwan between 1981 and 1990?

METHODS

The log-linear regression model was used to assess the effects of age, level of urbanization, and calendar year on the variation of childhood leukaemia incidence rates between 1981 and 1990.

RESULTS

Between 1981 and 1990, the overall incidence rate of childhood leukaemia increased by 20% (rate ratio (RR) = 1.2, 95% CI: 1.0-1.5). As compared to rural areas, metropolitan regions showed a significantly higher incidence rate during the study period (RR = 1.3, 95% CI: 1.1-1.6). This urban-rural difference was particularly notable among children <5 years old (RR = 1.5, 95% CI: 1.2-1.9). Dose-response analysis further indicated that risk of childhood leukaemia was monotonically associated with levels of urbanization. The significant gradient in the risk of childhood leukaemia with urbanization was contributed solely by children in the 0-4 years age group.

CONCLUSIONS

We noticed a relationship between urbanization and risk of leukaemia in children. Because of a dramatic influx of people into metropolitan areas during the 1980s, our findings may have provided support for the putative association between 'population mixing' or 'population density' and risk of childhood leukaemia. Whether such association can be attributable to virus infection or other aetiologically related leukemogens warrants further investigations.

Poor people on the move: county-to-county migration and the spatial concentration of poverty

"Poverty rates in high-poverty and low-poverty rural [U.S.] counties, and, thus, the spatial concentration of poverty, are affected by poverty-specific differences in in-migration and out-migration patterns. These patterns are investigated using 1985-90 county-to-county migration data from the decennial census. Effects on poverty rates of four migration flows (in- and out-migration of poor, in- and out-migration of nonpoor) are quantified, and their impacts on spatial concentration of poverty are assessed. The effect of selected county characteristics on the migration of the poor and nonpoor in nonmetro counties [is] estimated."

Population and employment density functions revisited: a spatial interaction approach

"This article proposes a generalized urban spatial structure and transportation network, and adapts the Garin-Lowry model to simulate both population and service employment densities in this hypothetical, yet realistic, city. The model is solved numerically while varying exogenous factors such as the distance friction coefficients and the spatial distribution of basic employment.... The results are generalized by estimating, via regression analysis, density functions over a large sample of simulated density patterns, pointing to the critical importance of transportation costs and basic employment distribution, and providing a basis for further empirical studies."

The relationship between population density and cancer mortality in Taiwan

Many investigators have examined urbanization gradients in cancer rates. The purpose of this report was to identify urban-rural trends in cancer mortality rates (1982-1991) for municipalities in Taiwan. For this purpose, Taiwan's municipalities were classified as rural, suburban, urban, or metropolitan, using population density as an ordinal indicator of the degree of urbanization. Average annual age-adjusted, site-specific cancer mortality rates were calculated for both sexes within each population density group. Significant increasing trends with more urbanization were observed in mortality rates for cancers of the lung, pancreas, and kidney among both males and females, as well as male prostate cancer, and female breast and ovary cancer. In addition, this study revealed a significant rural excess for nonmelanoma skin cancer among both males and females, as well as male non-Hodgkin's lymphoma, and cancers of the female bone, and female connective tissue. Analytic studies for sites with consistent urban-rural trends may be fruitful in identifying the aspect of population density, or other unmeasured factors, that contribute to these trends.

World population in a grid of spherical quadrilaterals

"We report on a project that converted subnational population data to a raster of cells on the earth. We note that studies using satellites as collection devices yield results indexed by latitude and longitude. Thus it makes sense to assemble the terrestrial arrangement of people in a compatible manner. This alternative is explored here, using latitude/longitude quadrilaterals as bins for population information.... The results to date of putting world boundary coordinates together with estimates of the number of people are described. The estimated 1994 population of 219 countries, subdivided into 19,032 polygons, has been assigned to over six million five minute by five minute quadrilaterals covering the world."

The facts about the urban exodus

"Urban deconcentration is the most dominant and consistent feature of population movement in Britain nowadays.... The scale of urban out-migration varies over time, some types of people and places are more fully represented in the urban exodus than others, and the net figures hide the fact that quite sizeable numbers of people move in the opposite direction.... The research was based largely in 1991 Population Census data on people who changed address within Great Britain during the year preceding Census night, focusing mainly on migration between local authority districts grouped according to their degree of 'urbanness' and their distance from the main metropolitan centres."

Density and the journey to work

"This paper evaluates the influence of residential density on commuting behavior across U.S. cities while controlling for available opportunities, the technology of transportation infrastructure, and individual socio-economic and demographic characteristics. The measures of metropolitan and local density are addressed separately.... Regressions are conducted to predict commuting time, speed, and distance, by mode of travel on a cross-section of individuals nationally and city by city. The results indicate that residential density in the area around the tripmaker's home is an important factor: the higher the density the lower the speed and the shorter the distance.... The paper suggests a threshold density at which the decrease in distance is overtaken by the congestion effects resulting in a residential density between 7,500 and 10,000 persons per square mile (neither the highest nor lowest) with the shortest duration auto commutes."

The earnings experience of rural-urban migrants in Korea

"Migration models in the Harris-Todaro tradition imply that urban informal sector earnings are less than rural sector earnings. Examining the situation for [South] Korea, we find that both urban formal and informal sector earnings exceed earnings opportunities in rural areas, making rural-urban migration the best decision for the individual and for the Korean economy in terms of maximizing output.... The implication for policy makers is that government efforts may be better directed toward mitigating the externalities caused by over-crowding, rather than attempting to influence population movements."

Preliminary evidence for a theory of the fractal city

"In this paper, we argue that the geometry of urban residential development is fractal. Both the degree to which space is filled and the rate at which it is filled follow scaling laws which imply invariance of function, and self-similarity of urban form across scale. These characteristics are captured in population density functions based on inverse power laws whose parameters are fractal dimensions. First we outline the relevant elements of the theory in terms of scaling relations and then we introduce two methods for estimating fractal dimension based on varying the size of cities and the scale at which their form is detected. Exact and statistical estimation techniques are applied to each method respectively generating dimensions which measure the extent and the rate of space filling. These methods are then applied to residential development patterns in six industrial cities in the northeastern United States...."

Demographic response to rural restructuring and counterurbanisation in South Australia, 1981-1991

"Using South Australia as a case study, this paper seeks to trace and demonstrate two processes (counterurbanisation and rural restructuring) whose effects overlap to differentiate and characterise the population geography of...two zones, separated by a transition along the outer fringe of Adelaide's urban field.... In the demographic core zone [rural restructuring] has been partly offset by continued counterurbanisation, resulting in demographic mixing and rural dilution. The 1981-91 population growth in rural communities is shown to be more a function of population density at the outset of the period than of initial population size. Demographic growth...is shown to conform to a simple unidimensional scale, allowing the production of a clear, easily interpretable typology of rural demographic change with few non-conforming statistical areas. At a local level within individual rural communities, demographic decline is shown to be accompanied by increased concentration of the population into small towns, while demographic growth is associated with deconcentration."