Conservation and Optimal Use of Rangelands

In previous papers we have considered the optimal mix of biodiversity in semi-arid rangelands, focusing on the steady state. This paper addresses the question of conservation in the optimal use of rangelands. That is, it considers the optimal trajectory of biodiversity change. There are two issues involved in the question of timing. One is the uncertainty associated with the fact that many changes in the flora and fauna of rangelands are 'event-driven'. They depend on stochastic parameters taking particular values before a change of state can occur. A second issue relates to the lag structure of changes. In a system that involves a mix of fast and slow variables, in which the approach to the optimum is not 'most rapid', the optimal trajectory may require the system to remain in an apparently stable intermediate equilibrium for some time before it converges to the optimum state. The paper discusses the role of conservation in the optimal use of rangeland resources.Biodiversity, Rangelands

La política norteamericana frente a la cocaína: pasado insatisfactorio, futuro incierto.

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Distributive laws, pseudodistributive laws and decagons

We give alternative definitions of distributive laws and pseudodistributive laws involving the decagonal coherence conditions which naturally arise when the involved monads and pseudomonads are presented in extensive form. We then use these results to give a number of simplifications in the coherence conditions for distributive laws and pseudodistributive laws. In particular, we show that five coherence axioms suffice in the usual definition of pseudodistributive laws, we give simple descriptions of distributive laws and pseudodistributive laws in terms of (pseudo)algebra structure maps, and we give concise definitions of distributive laws and pseudodistributive laws in no-iteration form.Comment: 27 pages; added the definition of a pseudodistributive law in no-iteration for