Construction of Bh[g] sets in product of groups

A subset A of an abelian group G is a Bh[g] set on G if every element of G can be written at most g ways as sum of h elements in A. In this work we present three constructions of Bh[g] sets on product of groups.Comment: 10 page

Searching by questionaire for the meaning of income inequality

Amien and Cowell (1992) have recently performed an experimental test by questionnaire to investigate whether a sample of individuals corroborate the general consensus found in the literature about a number of axioms on the meaning of 'inequality'. They obtained some mixed results. In this article we report on a replica of the experiment with some novelties: we introudce the role of political attitudes toward income redistribution to clarify the interpretation of some results; the questionnaire is enlarged in an attempt to give more room to notions of inequality imtermediate between the relative and absolute polar cases; and we provide a systematic treatment of the degree of consistency exhibited by the respondents

Testing lorentz and CPT invariance with ultracold neutrons

In this paper we investigate, within the standard model extension framework, the influence of Lorentz- and CPT-violating terms on gravitational quantum states of ultracold neutrons. Using a semiclassical wave packet, we derive the effective nonrelativistic Hamiltonian which describes the neutrons vertical motion by averaging the contributions from the perpendicular coordinates to the free falling axis. We compute the physical implications of the Lorentz- and CPT-violating terms on the spectra. The comparison of our results with those obtained in the GRANIT experiment leads to an upper bound for the symmetries-violation c(mu nu)(n) coefficients. We find that ultracold neutrons are sensitive to the a(i)(n) and e(i)(n) coefficients, which thus far are unbounded by experiments in the neutron sector. We propose two additional problems involving ultracold neutrons which could be relevant for improving our current bounds; namely, gravity-resonance spectroscopy and neutron whispering gallery wave.CONACyT [234745, 234774

Production externality and productivity of labor.

In this paper we consider two imperfectly competitive industries, with the polluting emissions from one industry harming the productivity of labor in the other. The polluting industry has to pay an environmental tax chosen by the government. In this framework, we analyze how the different organizational structure adopted by workers affect the environmental tax set by the government, total pollution emissions from the polluting industry and the productivity of workers in the industry that suffers the externality. We obtain that this depends on the degree to which pollution emissions from the polluting industry affects the marginal product of labor in the other industry.Production externality, productivity of labor, environmental taxes, imperfect competition, unionized labor.

Strategic Delegation and Semipublic Firms

By considering a mixed oligopoly and considering that public firms are less efficient than private firms, White (2001) shows that if private firms hire managers then the public firm does not do so. We show in this paper that if we consider that a private firm competes with a firm that is owned jointly by both the private and public sectors (a semipublic firm) and that all the firms are equally efficient, then in equilibrium both firms hire managers.Mixed duopoly, Semipublic Firms, Managerial incentive contracts, Cournot competition

A revision of the neotropical genus Anahi Martínez (Coleoptera: Scarabaeidae: Melolonthinae) with the description of two new species

El género Anahi Martínez del sur del Neotrópico es comprensivamente revisado y ahora contiene tres especies: A. dentata Ocampo & Ruiz- Manzanos especie nueva, A. guaraniticus Martínez y A. oblivia Ocampo & Ruiz-Manzanos especie nueva. Las nuevas especies extienden la distribución del género de Paraguay y Bolivia a Argentina. A. guaraniticus es redescripta y se amplían los caracteres que definen el género para incluir A. dentata y A. oblivia. Se proveen descripciones, ilustraciones diagnósticas, mapas de distribución y una clave para todas las especies del género. La biogeografía del género y su posición sistemática entre los Melolonthinae son tratados en este artículo. El género Anahi Martínez del sur del Neotrópico es comprensivamente revisado y ahora contiene tres especies: A. dentata Ocampo & Ruiz- Manzanos especie nueva, A. guaraniticus Martínez y A. oblivia Ocampo & Ruiz-Manzanos especie nueva. Las nuevas especies extienden la distribución del género de Paraguay y Bolivia a Argentina. A. guaraniticus es redescripta y se amplían los caracteres que definen el género para incluir A. dentata y A. oblivia. Se proveen descripciones, ilustraciones diagnósticas, mapas de distribución y una clave para todas las especies del género. La biogeografía del género y su posición sistemática entre los Melolonthinae son tratados en este artículo. The southern Neotropical genus Anahi Martínez is comprehensively revised and now includes three species: A. dentata Ocampo & Ruiz-Manzanos new species, A. guaraniticus Martínez, and A. oblivia Ocampo & Ruiz-Manzanos new species. The new species extend the distribution of the genus from Paraguay and Bolivia to Argentina. A. guaraniticus is redescribed and the characters that define the genus are extended to include A. dentata and A. oblivia. Descriptions, diagnosis illustrations, distribution maps and a key to all species of the genus are provided. The biogeography of the genus and its systematic placement within Melolonthinae are here discussed. The southern Neotropical genus Anahi Martínez is comprehensively revised and now includes three species: A. dentata Ocampo & Ruiz-Manzanos new species, A. guaraniticus Martínez, and A. oblivia Ocampo & Ruiz-Manzanos new species. The new species extend the distribution of the genus from Paraguay and Bolivia to Argentina. A. guaraniticus is redescribed and the characters that define the genus are extended to include A. dentata and A. oblivia. Descriptions, diagnosis illustrations, distribution maps and a key to all species of the genus are provided. The biogeography of the genus and its systematic placement within Melolonthinae are here discussed.The southern Neotropical genus Anahi Martínez is comprehensively revised and now includes three species: A. dentata Ocampo & Ruiz-Manzanos new species, A. guaraniticus Martínez, and A. oblivia Ocampo & Ruiz-Manzanos new species. The new species extend the distribution of the genus from Paraguay and Bolivia to Argentina. A. guaraniticus is redescribed and the characters that define the genus are extended to included, dentata and A. oblivia. Descriptions, diagnosis illustrations, distribution maps and a key to all species of the genus are provided. The biogeography of the genus and its systematic placement within Melolonthinae are here discussed.Fil: Ocampo, Federico Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Nebraska State Museum; Estados UnidosFil: Ruiz Manzanos, Eider. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentin

Another Consequence of the Economic Crisis: A Decrease in Migrants’ Remittances

The effects of the current global economic crisis are widespread. The economic downturn has affected large sectors of the population in developed and developing countries and international immigrants have not been the exception. This paper documents the recent slowdown in workers’ remittances, the money that international immigrants send to their countries of origin. Current data indicates that remittance flows have decreased for all regions of the world. Latin America stands out by reporting an almost zero percent growth rate of remittances for 2008. Among Latin American countries, Mexico (the largest recipient of remittances in the region in terms of volume) seems to be the most affected with a decrease of more than US$900 million between 2007 and 2008. This article also presents evidence of the impact of some of the factors associated with the current economic crisis on remittances flows. The results indicate that there is a strong link between housing activity in the United States and remittances flows.