Challenges in Hyperon Decays

We give an personal overview of some of the unsolved problems related to hyperon decays. We cover nonleptonic decays, radiative decays and magnetic moments. Some of the theoretical issues are also touched upon.Comment: Contribution to Workshop On Low-Energy Pbar Storage Ring (Pbar2000

Intention-based economic theories of reciprocity

Recientemente, varios experimentos han mostrado que los individuos exhiben un comportamiento auténticamente recíproco en interacciones anónimas que se dan una sola vez ('one-shot'). En tanto que se ha mostrado que la reciprocidad es relevante en múltiples campos de la economía, han existido varios intentos por modelar el comportamiento recíproco. Este documento revisa los modelos de reciprocidad que se fundamentan en las intenciones y presenta un ejemplo para el caso del manejo de los profesores en el sector público, en el que el gobierno ofrece un esquema de incentivos para la implementación de un programa. Este esquema tiene la estructura del dilema del prisionero. Tanto en los juegos simultáneos como secuenciales, los resultados de equilibrio puede ser distintos a los que predice la teoría convencional. ************************************************************************ In recent years, several experiments have shown that individuals exhibit authentic reciprocal behavior in anonymous one-shot interactions. As reciprocity has been shown to be relevant in several economic fields, there have also been several attempts to model reciprocical behavior. I review the intention-based models of reciprocity and present an example in teachers´ management in the public sector in which a government offers an incentive scheme to implement a program. The incentive scheme has the prisioner’s dilemma structure, In both simultaneous and sequential games, in equilibrium reciprocal teachers may reach other equilibria different from those predicted by the standard theory.Game theory, psychological games,Intention-based models, reciprocl behaviour

Darwin's Other Books: “Red” and “Transmutation” Notebooks, “Sketch,” “Essay,” and Natural Selection

Study of Darwin's unpublished works, freely available on-line through the American Natural History Museum, reveals the origins of his thoughts on evolution

On Exactly Solvable Potentials

We investigate two methods of obtaining exactly solvable potentials with analytic forms.Comment: 13 pages, Latex, to appear in Chineses Journal of Physic

Does Aid Induce Brain Drain? The Effect of Foreign Aid on Migration Selection

Recent evidence suggests that aid induces migration. However, total migration is quite general from a policy perspective since what explains the welfare consequences of migration is the extent of emigration selection. In this paper we ask whether skilled or unskilled migration is more sensitive to aid and to the different mechanisms through which aid may affect self-selection among international emigrants. We show that aid induces positive selection. And that the effect on skilled migration is larger than the effect on unskilled migration. As possible mechanisms to explain the relation, we find that aid induces skilled migration by reducing transaction and information costs, by improving the distribution of schooling, and by helping to overcome liquidity constraints.Foreign aid, International migration, Self-selection, Brain drain.

Supposedly Strong Instruments and Good Leverage Points

In this paper, we warn on the overoptimistic conclusions led by weak instruments testing when good leverage points are present in the first stage of an IV estimation. Some simulations and an empirical application are provided to illustrate the point raised.Instrumental variables, Weak instruments, Outliers, Robust statistics

Darwinian Selection and Non-existence of Nash Equilibria

We study selection acting on phenotype in a collection of agents playing local games lacking Nash equilibria. After each cycle one of the agents losing most games is replaced by a new agent with new random strategy and game partner. The network generated can be considered critical in the sense that the lifetimes of the agents is power law distributed. The longest surviving agents are those with the lowest absolute score per time step. The emergent ecology is characterized by a broad range of behaviors. Nevertheless, the agents tend to be similar to their opponents in terms of performance.Comment: 4 pages, 5 figure