Abstract: Improving soil carbon through conservation agriculture in developing countries may generate some private benefits to farmers, as well as sequester carbon emissions, which is a positive externality to society. Leaving crop residue on the farm has become an important option in conservation agriculture practice. However, in developing countries, using crop residue for conservation agriculture has the opportunity cost of feed for livestock. In this paper, we model and develop an expression for an optimum economic incentive that is necessary to internalize the positive externality. A crude value of the tax is calculated using data from Kenya. We also empirically investigated the determinants of the crop residue left on the farm and found that it depends on the cation exchange capacity (CEC) of the soil, the prices of maize, whether extension officers visit the plot or not, household size, the level of education of the household head, and alternative cost of soil conservation.

Abstract: Since the energy crisis in the 1970s and later the growing concern for climate change in the 1990s, policymakers at all levels of government and around the world have been enthusiastically supporting a wide range of incentive mechanisms for electricity from renewable energy sources (RES-E). Motivations range from energy security to environmental preservation to green jobs and innovation, and measures comprise an array of subsidies to mandates to emissions trading. But do these policies work together or at cross-purposes? To evaluate RES-E policies, one must understand how specific policy mechanisms interact with each other and under what conditions multiple policy levers are necessary. In this article, we review the recent environmental economics literature on the effectiveness of RES-E policies and the interactions between them, with a focus on the increasing use of tradable quotas for both emissions reduction and RES-E expansion.

Abstract: This study suggests that reducing fertility should be a primary policy variable used in concert with macroeconomic policies and poverty reduction strategies. It empirically verifies the existence of a poverty demography trap by analyzing survey data from two regions in northern Tanzania. It first summarizes the macro and microeconomic issues of the relationship between GDP and population growth, highlighting poverty and demographic variables in Africa and in Tanzania. The number of children ever born (CEB) and household size in the study area indicate a high rate of population growth. Non-nuclear household members are about 23 percent, indicating heavy population pressure on household resources. The demographic variables were classified with selected poverty indicators (undernutrition and malnutrition; monetary expenditure; and access to land, clean water, sanitary facilities, and energy sources). The results showed moderate undernutrition and acute malnutrition associated with CEB and household size. Large households tend to spend much less on food, compared to smaller households. The mean weekly expenditure among households with six members is a meager US$5. As much as 50 percent of farming households do not own land and depend on wood for energy needs. Access to clean water, modern toilet facilities, and electricity is very poor, especially among large households. Getting out of the poverty trap implies reducing fertility and vice versa.

Abstract: We demonstrate the diffusion in use of Earth observations data in social science research. Our study is motivated by the continuing debate among policymakers over the value of the nation’s investment in Earth observations. We also consider the role of related factors including the spread of geographical information systems (GIS; a complementary tool for using Earth observations data) and the role of data prices. We first estimate a diffusion curve and then draw from standard bibliometric methods to evaluate further the extent to which the research field is growing. We realize that these aspects of the value of Earth observations are often part of policy debate, but we offer insights into how to substantiate and document these claims. We find evidence of increasingly widespread use of Earth observations in an ever-widening number of applications and geographic regions. GIS and data prices influence this diffusion. However, we see less evidence of a community of practice within the large social science literature represented in our data. These findings have implications for steps to take to increase the benefits of Earth observations.

Abstract: We consider a health authority seeking to allocate annual budgets optimally over time to minimize the discounted social cost of infection(s) evolving in a finite set of R >/= 2 groups. This optimization problem is challenging, since as is well known, the standard epidemiological model describing the spread of disease (SIS) contains a nonconvexity. Standard continuous-time optimal control is of little help, since a phase diagram is needed to address the nonconvexity and this diagram is 2 R dimensional (a costate and state variable for each of the R groups). Standard discrete-time dynamic programming cannot be used either, since the minimized cost function is neither concave nor convex globally. We modify the standard dynamic programming algorithm and show how familiar, elementary arguments can be used to reach conclusions about the optimal policy with any finite number of groups. We show that under certain conditions it is optimal to focus the entire annual budget on one of the R groups at a time rather than divide it among several groups, as is often done in practice; faced with two identical groups whose only di fference is their starting level of infection, it is optimal to focus on the group with fewer sick people. We also show that under certain conditions it remains optimal to focus on one group when faced with a wealth constraint instead of an annual budget.

Abstract: The nature of competition across space can be fundamentally altered by changes in market institutions. We propose a new framework that allows for the inclusion of market-altering policy changes in the spatial analysis of competitive behavior. This paper fills a gap in the literature between work that focuses on spatial price responsiveness of agents to one another and the literature that explores how policy changes in market regulations affect the competitive behavior of agents. Specifically, we account for how a change in fisheries management (the creation of catch shares) affects the spatial responsiveness of fish processors across a 21-year time period. We also introduce a method that allows for the incorporation of breaks of explanatory variables in spatial panel data sets.