Heterogeneity and the formation of risk - sharing coalitions

We offer a new explanation of partial risk sharing based on coalition formation and segmentation of society in a risky environment, without assuming limited commitment and imperfect information. Heterogenous individuals in a society freely choose with whom they will share risk. A partition belonging to the core of the membership game obtains. Perfect risk sharing does not necessarily arise. Focusing on mutual insurance rule and assuming that individuals only differ with respect to risk, we show that the core partition is homophily-based. The distribution of risk affects the number and size of these coalitions. Individuals may pay a lower risk premium in riskier societies. A higher heterogeneity in risk leads to a lower degree of risk sharing. We discuss how the endogenous partition of society into risk-sharing coalitions may shed light on empirical evidence on partial risk sharing. The case of heterogenous risk aversion leads to similar results.

Modeling tuition fees in presence of social heterogeneity. 'Como modelar las tasas de matrícula en presencia de la heterogeneidad social'.

Resumen basado en el de la publicación

On the farm.

Presenta algunas de las diferentes máquinas utilizadas en las explotaciones agrícolas, incluidos los arados, tractores, máquinas de ordeño, para abonado con estiércol o purinas, esquilado, para plantar semillas, cosechadoras, o para cortar y hacer las balas de pasto, y cosechadoras. Un glosario ilustrado proporciona una primera herramienta de referencia para las máquinas que aparecen en la publicación. Para niños hasta siete años.

Farm 123.

Un primer libro para aprender a contar del uno al diez con los animales de la granja. Levanta las solapas y descubre lo que se esconde debajo de ellas.

A farm through time : the history of a farm from medieval times to the present day.

Esta es la historia de una granja y de su emplazamiento desde la Alta Edad Media hasta la actualidad. Vemos la evolución de la explotación agrícola y ganadera, de sus dependencias y viviendas; se muestra el impacto causado en el paisaje que la rodea. Y aunque, hay actividades que continúan inalterables a lo largo de los siglos, el progreso científico ha introducido la maquinaría en ellas y esto motiva la desaparición de formas de vida, oficios y costumbres tradicionales.

About the farm.

Esta concebido para que los niños desarrollen destrezas de lectura desde muy temprano, para ello se les acostumbra a mover los ojos de izquierda a derecha, es decir, en el sentido de la lectura y, también al simple reconocimiento de palabras ó con el apoyo de las ilustraciones. El texto de la izquierda introduce en cada página una palabra nueva en el vocabulario, que es recalcada en el recuadro inferior de la derecha. En este caso, los niños aprenden palabras de animales que viven en una granja: gallina, cerdos, ovejas, caballos.

Optimal management of natural resources. Accounting for heterogeneity

Dynamic optimization methods have become increasingly important over the last years in economics. Within the dynamic optimization techniques employed, optimal control has emerged as the most powerful tool for the theoretical economic analysis. However, there is the need to advance further and take account that many dynamic economic processes are, in addition, dependent on some other parameter different than time. One can think of relaxing the assumption of a representative (homogeneous) agent in macro- and micro-economic applications allowing for heterogeneity among the agents. For instance, the optimal adaptation and diffusion of a new technology over time, may depend on the age of the person that adopted the new technology. Therefore, the economic models must take account of heterogeneity conditions within the dynamic framework. This thesis intends to accomplish two goals. The first goal is to analyze and revise existing environmental policies that focus on defining the optimal management of natural resources over time, by taking account of the heterogeneity of environmental conditions. Thus, the thesis makes a policy orientated contribution in the field of environmental policy by defining the necessary changes to transform an environmental policy based on the assumption of homogeneity into an environmental policy which takes account of heterogeneity. As a result the newly defined environmental policy will be more efficient and likely also politically more acceptable since it is tailored more specifically to the heterogeneous environmental conditions. Additionally to its policy orientated contribution, this thesis aims making a methodological contribution by applying a new optimization technique for solving problems where the control variables depend on two or more arguments --- the so-called two-stage solution approach ---, and by applying a numerical method --- the Escalator Boxcar Train Method --- for solving distributed optimal control problems, i.e., problems where the state variables, in addition to the control variables, depend on two or more arguments. Chapter 2 presents a theoretical framework to determine optimal resource allocation over time for the production of a good by heterogeneous producers, who generate a stock externalit and derives government policies to modify the behavior of competitive producers in order to achieve optimality. Chapter 3 illustrates the method in a more specific context, and integrates the aspects of quality and time, presenting a theoretical model that allows to determine the socially optimal outcome over time and space for the problem of waterlogging in irrigated agricultural production. Chapter 4 of this thesis concentrates on forestry resources and analyses the optimal selective-logging regime of a size-distributed forest.

Development of practical methodology and indicators for on-farm animal welfare assessment

163 p.