BACKGROUND With a view to addressing the moral concerns about the use of donor siblings, the Policy Statement of the American Academy of Pediatrics - Children as Hematopoietic Stem Cell Donors (the Policy) has laid out the criteria upon which tissue harvest from a minor would be permissible. DISCUSSION Although tissue harvest serves the best interests of recipient siblings, parents are also o...

The optimal harvesting policy is calculated as a function of the entering stock, the price state, the harvesting cost, and the rate of interest in the capital market. In order to determine the optimal harvest schedule, the growth function and stumpage price process are estimated for the Swedish mixed species forests. The stumpage price is assumed to follow a stochastic Markov process. A stochas...

Innovative methodology is developed for Back to the Future (BTF) restoration policy analysis to aid long-term strategic planning of ecosystem-based restoration in marine ecosystems. Massbalance and dynamic ecosystem simulation models (Ecopath with Ecosim: EwE) are developed to represent the marine system of northern British Columbia as it appeared in 1750, 1900, 1950 and 2000 AD. Time series st...

We characterize the optimal harvest of a renewable resource in a generalized stochastic spatially explicit model. Despite the complexity of the model, we are able to obtain sharp analytical results. We find that the optimal harvest rule in general depends upon dispersal patterns of the resource across space, and only in special circumstances do we find a modified golden rule of growth that is i...

Change in the size of populations over space and time is, arguably, the motivation for much of pure and applied ecological research. The fundamental model for the dynamics of any population is straightforward: the net change in the abundance is the simple difference between the number of individuals entering the population and the number leaving the population, either or both of which may chang...

An intense scholarly and public policy debate concerns the optimal design of political institutions for new democracies, particularly those facing deep ethnic or cultural cleavages. Drawing on a book-length study of political engineering in the AsiaPacific region, this paper surveys the differences between consociational and centripetal approaches to institutional design. After examining the ke...

A single species stage-structured model incorporating both toxicant and harvesting is proposed and studied. It is shown that toxicant has no influence on the persistent property of the system. The existence of the bionomic equilibrium is also studied. After that, we consider the system with variable harvest effect; sufficient conditions are obtained for the global stability of bionomic equilibr...

Stage dependent predation may give rise to the hydra effect--the increase of predator density at equilibrium as its mortality rate is raised. Management strategies that adjust predator harvest rates or quotas based on responses of populations to past changes in capture rates may eventually lead to a catastrophic collapse of predator species. A proposed threshold management policy avoids the hyd...

IFPRI was established in 1975 to identify and analyze national and international strategies and policies for meeting the food needs of the developing world on a sustainable basis, with particular emphasis on low-income countries and poor people; to make the results of its research available to all those in a position to use them; and to help strengthen institutions conducting research and apply...