1,498,990 research outputs found

    Population, Population Density, and Technological Change

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    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.

    Earthworm Population Density in Sugarcane Cropping System Applied with Various Quality of Organic Matter

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    Earthworms population in the soil are greatly impacted by agricultural management, yet little is known about how the quality and quantity of organic matter addition interact in sugarcane cropping system to earthworm population. This study describes the effect of various organic matter and application rates on earthworms in sugarcane cropping system. Earthworms were collected in April, July and December from 48 experimental plots under five kinds of organic matter application : (1) cattle manure, (2) filter cake of sugar mill, (3) sugarcane trash, (4) mixture of cattle manure+filter cake, and (5) mixture of cattle manure+sugarcane trash. There were three application rates of the organic matter (5, 10, and 15 ton ha-1). The treatments were arranged in factorial block randomize design with three replications and one treatment as a control (no organic input). Earthworms were collected using monolith sampling methods and hand-sorted from each plot, and measured its density (D) (indiv.m-2), biomass (B) (g m-2) and B/D ratio (g/indiv.). All the plots receiving organic matter input had higher earthworm density, biomass, and B/D ratio than the control. The highest earthworm population density was found in the plot receiving application of sugarcane trash (78 indiv.m-2) and the mixture of cattle manure+sugarcane trash (84 indiv.m-2). The increase in application rates of organic matter could increase the earthworm density and biomass. Earthworm population density also appeared to be strongly influenced by the quality of organic matter, such as the C-organic, N, C/N ratio, lignin, polyphenols, and cellulose content. Earthworm preferred low quality organic matter. It was caused by the higher energy of low quality organic matter than high quality organic matter. Our findings suggest that the input of low quality organic matter with application rate as 10 ton ha-1 is important for maintaining earthworm population and soil health in sugarcane land

    Estimation of Population Density and Food Sort of KELASI (Presbytis Rubicundamuller 1838) in Nyaru Menteng Arboretum of Palangka Raya

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    Nyaru Menteng Arboretum is one of Conservation area in Palangka Raya for biodiversity protection width 65,2ha and in that area have established an Orang Utan Reintroduction Center from Borneo Orangutan Save Foundation (BOSF). The aims of this research are to estimated the population density of Kelasi in this area and to know many kinds of Kelasi food and the part of trees that Kelasi put to eat. The result of this research that has found one species (young class) in January 2017, then we can find 3 species again in April 2017 there is one male, one female, and one young kelasi. Population density rate of Kelasiof 2017 is 0,06 species/ha that meaning is population density of Kelasi have a degraded experience if comparing with the same population density data on 2007 that found 15 species in the area (in 2 group)with 0,23 species/ha. Food sort of Kelasi is juvenile of : Jambu-jambu (Syzgium cerinum), Saga (Adenathera microsperma), cassava (Manihot utilisima), rubber (Hevea brasiliensis), pineapple (Ananas comosus), Kelakai (Stenochlaena ralustris) dan jackfruit (Artocarpus integra), other fruits and residue of orangutan food in Reintroduction area lie pineapple and papaya

    Distributed MPC with time-varying communication network: A density-dependent population games approach

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    © 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This work addresses distributed control design by using density-dependent population dynamics. Furthermore, stability of the equilibrium point under this proposed class of population dynamics is studied, and the relationship between the equilibrium point of density-dependent population games (DDPG) and the solution of constrained optimization problems is shown. Finally, a distributed predictive control is designed with the proposed density-dependent dynamics, and contemplating a time-varying communication network.Peer ReviewedPostprint (author's final draft

    Evolutionary Stable Strategies Depending on Population Density

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    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 Social Consequences of High Population Density

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    Density dependence and the control of helminth parasites.

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    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

    Population density and regional welfare efficiency

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    This paper demonstrates an evaluation of welfare policies and regional allocation of public investment using Data Envelopment Analysis (DEA). Specifically, the efficiency of the welfare policies of the Greek prefectures for the census years of 1980, 1990 and 2000 are compared and analyzed. The paper using bootstrap techniques on unconditional and conditional full frontier applications determines whether the government investments have been used efficiently by the local authorities in order to stimulate regional welfare among the Greek prefectures. Our empirical results indicate that there are major welfare inefficiencies among the prefectures over the three census years. The analysis reveals that the population density among the Greek prefectures hasn’t been taken into account in regional welfare planning over the years. In addition, the paper demonstrates empirically how the new advances in DEA analysis can be incorporated into different stages of regional planning investment and evaluation. In addition, the impact of external factors can be directly measured and evaluated accordingly.Regional development; Welfare policies; Conditional DEA; Bootstrap techniques; Kernel density estimation
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