Equilibrium Selection and the Rate of Convergence in Coordination Games with Simultaneous Play

We apply the dynamic stochastic framework proposed in the recent evolutionary literature to a class of coordination games played simultaneously by the entire population. In these games, payoffs whence best replies are determined by a summary statistic of the population strategy profile. We demonstrate that with simultaneous play, the equilibrium selection depends crucially on how best responses to the summary statistic remain piece-wise constant. In fact, all the strict Nash equilibria in the underlying stage game can be declared stochastically stable depending on how the best response mapping generates piece-wise constant best responses. Furthermore, we show that if the best response mapping is sufficiently asymmetric, the expected waiting time until the unique stochastically stable state is reached is of the same order as the mutation rate, even in the limit as the population size grows to infinity.equilibrium selection; stochastic stability; waiting time; rate of convergence

Discrete Public Goods with Incomplete Information

We investigate a simultaneous discrete public good provision game with incomplete information. To use the terminology of Admati and Perry (1991), we consider both contribution and subscription games. In the former, contributions are not refunded if the project is not completed, while in the latter they are. In the presence of complete information about individuals' valuations for the public good, the difference between the equilibrium outcomes of a subscription game and a contribution game is not significant. However, there is both casual evidence from the fund-raising literature and experimental evidence that subscription games are ``superior '', i.e., a refund increases the chance of providing the good given that it is efficient to do so. Our analysis shows that this is indeed the case in the presence of incomplete information. We compute a symmetric equilibrium for the subscription game and show that it is not necessarily efficient. This inefficiency stems from the difficulties arising in coordinating to overcome the free-rider problem in the presence of incomplete information. Although it is well known that informational disparities impose limits on the efficiency of outcomes, the novel feature of our analysis is to explicitly model the resulting trade-off --- when deciding how much to contribute towards the public good --- between increasing the likelihood of provision and creating incentives for free-riding by the other player. Moreover, we show that for the contribution game, ``contributing zero'' is the only equilibrium for a given range of the fixed cost of provision and for a family of distributions.public goods; incomplete information; continuous distribution

Kaon condensation in the quark-meson coupling model and compact stars

The properties of neutron stars constituted of a crust of hadrons and an internal part of hadrons and kaon condensate are calculated within the quark-meson-coupling model. We have considered stars with nucleons only in the hadron phase and also stars with hyperons as well. The results are compared with the ones obtained from the non-linear Walecka model for the hadronic phase.Comment: 10 pages, 6 figure

Stellar matter in the Quark-Meson-Coupling Model with neutrino trapping

The properties of hybrid stars formed by hadronic and quark matter in $\beta$-equilibrium are described by appropriate equations of state (EoS) in the framework of the quark meson coupling (QMC) model. In the present work we include the possibility of trapped neutrinos in the equation of state and obtain the properties of the related hybrid stars. We use the quark meson coupling model for the hadron matter and two possibilities for the quark matter phase, namely, the unpaired quark phase and the color-flavor locked phase. The differences are discussed and a comparison with other relativistic EoS is done.Comment: Reference added, accepted in PR

Relativistic Equation of state with short range correlations

Short range correlations are introduced using unitary correlation method in a relativistic approach to the equation of state of the infinite nuclear matter in the framework of the Hartree-Fock approximation. The effect of the correlations in the ground state properties of the nuclear matter is studied.Comment: 4 pages, 4 figure

Warm stellar matter with neutrino trapping

The properties of hybrid stars formed by hadronic and quark matter in beta-equilibrium at fixed entropies are described by appropriate equations of state (EOS) in the framework of relativistic mean-field theory. In this work we include the possibility of neutrino trapped EOS and compare the star properties with the ones obtained after deleptonization, when neutrinos have already diffused out. We use the nonlinear Walecka model for the hadron matter with two different sets for the hyperon couplings and the MIT Bag and the Nambu-Jona-Lasinio models for the quark matter. The phase transition to a deconfined quark phase is investigated. Depending on the model and the parameter set used, the mixed phase may or may not exist in the EOS at high densities. The star properties are calculated for each equation of state. The maximum mass stellar configurations obtained within the NJL have larger masses than the ones obtained within the Bag model. The Bag model predicts a mixed phase in the interior of the most massive stable stars while, depending on the hyperon couplings, the NJL model predicts a mixed phase or pure quark matter. Comparing with neutrino free stars, the maximum allowed baryonic masses for protoneutron stars are $\sim 0.4 M_\odot$ larger for the Bag model and $\sim 0.1 M_\odot$ larger for the NJL model when neutrino trapping is imposed.Comment: 8 pages, 8 figures, 1 tabl

Pentaquarks in the medium in the quark-meson coupling model

We calculate the properties of the pentaquarks $\Theta^+$ and $\Xi^{--,0}$ in symmetric nuclear matter using the quark meson coupling model (QMC). The stability of the $\Theta^+$ in the medium with respect to the channel $\Theta^+\to NK^+$ is discussed.Comment: 6 pages, 5 figures, revte

Compact stars within an asy-soft quark-meson-coupling model

We investigate compact star properties within the quark meson coupling model (QMC) with a soft symmetry energy density dependence at large densities. In particular, the hyperon content and the mass/radius curves for the families of stars obtained within the model are discussed. The hyperon-meson couplings are chosen according to experimental values of the hyperon nuclear matter potentials, and possible uncertainties are considered. It is shown that a softer symmetry energy gives rise to stars with less hyperons, smaller radii and larger masses. Hyperon-meson couplings may also have a strong effect on the mass of the star.Comment: 7 pages, revtex, accepted in Phys. Rev.

Corruption and Auctions

We investigate the outcome of an auction where the auctioneer approaches one of the two existing bidders and offers an opportunity for him to match his opponent's bid in exchange for a bribe. In particular, we examine two types of corruption arrangements. In the first case, the auctioneer approaches the winner to offer the possibility of a reduction in his bid to match the loser's bid in exchange for a bribe. In the second arrangement, the auctioneer approaches the loser and offers him the possibility of matching the winner's bid in exchange for a bribe. While oral auctions are corruption free under the two arrangements, corruption affects both bidding behavior, efficiency and the seller's expected revenue in a first­price auction

Análise da capacidade produtiva de própolis em diferentes espécies de abelhas sem ferrão.

A criação de abelhas sem ferrão, conhecida como Meliponicultura, visa principalmente a produção de mel, porém outros produtos também podem ser gerados pela atividade, como pólen, cera e própolis. Esta última ainda não é bem difundida por falta de estudos na área. A própolis é uma mistura de resinas vegetais coletadas pelas abelhas a partir de troncos e secreções de árvores. É utilizada para fazer a proteção da colônia contra inimigos naturais: formigas, forídeos, lagartixas e aranhas. O trabalho foi realizado no laboratório de Botânica da EMBRAPA Amazônia Oriental, no período de Setembro de 2013 à Janeiro de 2014. Utilizou-se 6 espécies de abelhas sem ferrão: Frieseomelita cf. longipes, Frieseomelitta flavicornis, Scaptotrigona postiça, Melipona melanoventer, Melipona fasciculata e Melipona flavolineata. A três primeiras espécies produzem própolis puro, enquanto as demais produzem uma mistura de própolis com barro, chamada de batume. Foram usadas 3 colônias de cada espécie e utilizou-se de coletores de própolis para a realização do trabalho. O própolis foi removido cada 15 dias. A espécie produtora de batume que mais se destacou foi a M. flavolineata com cerca de 215,56 g (±129,56), enquanto que relacionado a produção de própolis, a espécie F. cf. longipes produziu em média 39,95 g (±17,29), ambas a cada 15 dias. As amostras estão sendo guardadas para análises futuras de atividade biológica e farmacológica, a fim de descobrir benefícios que a própolis de abelhas sem ferrão podem trazer e consequentemente agregar valor econômico à mesma