2,631 research outputs found
Keeping an eye on decentralization and specification of a resource policy: An overview of the policy study to the promotion of RWH
Water policyRainWater harvestingSoil conservationIrrigation waterWater rights
Entry, survival, and growth of manufacturing firms in Ethiopia
econometric analysis;Ethiopia;manufacturing;business economics
Poverty, Resource Scarcity and Incentives for Soil and Water Conservation: Analysis of Interactions with a Bio-economic Model
The paper examines the interlinkages between population pressure and poverty, possible impacts on household welfare and land management, and the consequent pathways of development in a low potential rural economy. A dynamic non-separable bio-economic model, calibrated using data from the Ethiopian highlands, is used to trace key relationships between population pressure, poverty and soil fertility management in smallholder agriculture characterized by high levels of soil degradation. Farm households maximize their discounted utility over the planning horizon. Land, labor and credit markets are imperfect. Hence, production, consumption and investment decisions are jointly determined in each period. The level of soil degradation is endogenous and has feedback effects on the stock and quality of the resource base. This may in turn influence land management choices. Under high population pressure, land becomes dearer relative to labor. This is likely to induce conservation investments, especially when conservation technologies do not take land out of production. When markets are imperfect, poverty in vital assets (e.g., oxen and labor) limits the ability or the willingness to invest in conservation and may lead to a less sustainable pathway. Boserup-type responses are more likely when (privately) profitable technologies exist and market imperfections do not limit farm-households' investment options.Resource /Energy Economics and Policy,
Localization of polymers in a finite medium with fixed random obstacles
In this paper we investigate the conformation statistics of a Gaussian chain
embedded in a medium of finite size, in the presence of quenched random
obstacles. The similarities and differences between the case of random
obstacles and the case of a Gaussian random potential are elucidated. The
connection with the density of states of electrons in a metal with random
repulsive impurities of finite range is discussed. We also interpret the
results obtained in some previous numerical simulations.Comment: 23 pages, 3 figures, revte
Polymers with self-avoiding interaction in random media: a localization-delocalization transition
In this paper we investigate the problem of a long self-avoiding polymer
chain immersed in a random medium. We find that in the limit of a very long
chain and when the self-avoiding interaction is weak, the conformation of the
chain consists of many ``blobs'' with connecting segments. The blobs are
sections of the molecule curled up in regions of low potential in the case of a
Gaussian distributed random potential or in regions of relatively low density
of obstacles in the case of randomly distributed hard obstacles. We find that
as the strength of the self-avoiding interaction is increased the chain
undergoes a delocalization transition in the sense that the appropriate free
energy per monomer is no longer negative. The chain is then no longer bound to
a particular location in the medium but can easily wander around under the
influence of a small perturbation. For a localized chain we estimate
quantitatively the expected number of monomers in the ``blobs'' and in the
connecting segments.Comment: 20 pages, 2 figures, revtex
A simple bivariate count data regression model
This paper develops a simple bivariate count data regression model in which dependence between count variables is introduced by means of stochastically related unobserved heterogeneity components. Unlike existing commonly used bivariate models, we obtain a computationally simple closed form of the model with an unrestricted correlation pattern.
Tobacco Chewing, Smoking and Health Knowledge: Evidence from Bangladesh
Unlike the substance abuse studies in developed countries, tobacco consumption and its adverse effects in developing countries are poorly studied. The objective of this paper is to identify which factors influence individuals' decision to smoke cigarettes, chew tobacco and their knowledge about the health hazards of tobacco use. To allow for the potential correlation among smoking tobacco, chewing tobacco, and health knowledge, we estimate a trivariate probit regression model using household survey data from Bangladesh. For both chewing tobacco and smoking, the results show how the probabilities of uninformed tobacco user and uninformed nonuser vary across different demographic groups.Chewing tobacco
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