Population, Population Density, and Technological Change

In a model on population and endogenous technological change, Kremer combines a short-run Malthusian scenario where income determines the population that can be sustained, with the Boserupian insight that greater population spurs technological change and can therefore lift a country out of its Malthusian trap. We show that a more realistic version of the model, which combines population and population density, allows deeper insights into these processes. The incorporation of population density also allows a superior interpretation of the empirical regularities between the level of population, population density, population growth, and economic development, both at aggregated and disaggregated levels.

Evolutionary Stable Strategies Depending on Population Density

The concept of evolutionary stable strategies is extended to include density dependence. Dynamical stability is shown to follow for two-strategy games and for symmetric payoff matrices. It is conjectured that stability also results for general multi-strategy games

The Strength of Association: Population Density and Social Deviance

This issue is the second of three in Series 3a, "The Strength of Community-level Rates of Association," mapping Anchorage neighborhood characteristics by census block area, highlighting the correlation or lack of correlation between those characteristics and the level of crime and social deviance in the neighborhood as measured by police calls for service for six types of offenses. Maps in this subseries should be compared with the maps in Series 3b, "An Examination of Police Service Deployment (Police Calls for Service)," for a full picture of the "strength of association."This issue of Anchorage Community Indicators provides a brief examination of the relationship between population density and social deviance in the Municipality of Anchorage. A commonly held belief is that social density is positively correlated with social deviance, despite only sparse scientific evidence in support of this theory. A previous issue of Anchorage Community Indicators ("The Strength of Association: Housing Density and Delinquency," ACI 3a(1) (Jul 2004)) found no evidence of a relationship between housing density and deviance. The current issue builds on these previously reported findings by introducing a second measure of social density: population density, once again finding no evidence that social density of Anchorage neighborhoods is associated with community-level rates of social deviance

Density dependence and the control of helminth parasites.

1. The transient dynamics and stability of a population are determined by the interplay between species density, its spatial distribution and the positive and negative density-dependent processes regulating population growth. 2. Using the human-helminth parasite system as an example, we propose that the life-stage upon which negative density dependence operates will influence the rate of host reinfection following anthelmintic chemotherapy, and the likely success of control programmes. 3. Simple deterministic models are developed which highlight how a parasite species whose population size is down-regulated by density-dependent establishment will reinfect a host population at a faster rate than a species with density-dependent parasite fecundity. 4. Different forms of density dependence can produce the same equilibrium behaviour but different transient dynamics. Under-representing the nature and magnitude of density-dependent mechanisms, and in particular those operating upon establishing life-stages, may cause the resilience of the parasite population to a control perturbation to be underestimated

Radial propagation in population dynamics with density-dependent diffusion

The population dynamics that evolves in the radial symmetric geometry is investigated. The nonlinear reaction-diffusion model, which depends on population density, is employed as the governing equation for this system. The approximate analytical solution to this equation has been found. It shows that the population density evolves from initial state and propagates as the traveling wave-like for the large time scale. One can be mentioned that, if the distance is insufficient large, the curvature has ineluctable influence on density profile and front speed. In comparison, the analytical solution is in agreement with the numerical solution.Comment: 4 pages, 2 figures, major revisio