We consider modifications to the Friedmann equation motivated by recent proposals along these lines pursuing an explanation to the observed late time acceleration. Here we show those modifications can be framed within a theory with self-interacting gravity, where the term self-interaction refers here to the presence of functions of ρ and p in the right hand side of the Einstein equations. We then discuss the construction of the duals of the cosmologies generated within that framework. After that we investigate the modifications required to generate generalized and modified Chaplygin cosmologies and show that their duals belong to a larger family of cosmologies we call extended Chaplygin cosmologies. Finally, by letting the parameters of those models take values not earlier considered in the literature we show some representatives of that family of cosmologies display sudden future singularities, which indicates their behavior is rather different from generalized or modified Chaplygin gas cosmologies. This reinforces the idea that modifications of gravity can be responsible for unexpected evolutionary features in the universe.

In the early twentieth century, the US Forest Service began to exclude itinerant sheep operations from the public-domain lands it administered: the National Forests. But beyond the National Forests, the extensive public-domain lands devoted to grazing were not regulated. To some local ranchers and stockmen, the increasing presence of itinerant sheepherders, including Basque immigrants, represented the first of a growing number of competitors on Nevada’s public-domain lands. These stockmen blamed itinerant sheepherders for all the problems affecting the water and grassland ecosystems, such as the deterioration of the ranges and the fouling of springs and streams. Their representatives requested an expansion of National Forest boundaries as a means of asserting exclusive use of the range for stockmen. Although at first the Forest Service keenly appreciated the problems of local stock raisers, it opposed the idea of expanding the National Forests in Nevada solely for the purpose of range control. This article explores how some ranchers advocated expanding the National Forest lands within the State of Nevada as a strategy to protect their economic interests and force itinerant sheepherders out of business.

The Mexican corrido is one of the most popular cultural manifestations both in the United States and Mexico. From its origins in the mid-nineteenth century, the corrido has dealt with “people’s stuff,” such as war, love, honor, immigration and/or belonging to a land, among other everyday life issues. The corrido is, in short, a symbol of identity and belonging, and can be considered a marker of the Mexican identity on both sides of the border. In this sense, it is to be expected that the corrido, as an expression of “people’s stuff,” voices the relevance of a “national” symbol. In the same way, tequila is regarded, at least internationally, as directly related to “lo mexicano/chicano,” and in many cases also to Mexican/Chicano masculinity. Starting from this premise, the aim of this article is to observe the presence of tequila and its significance as a symbol of “lo mexicano/chicano” in the work of Los Tigres del Norte, one of the most prominent corrido bands, both locally and internationally.

SUMA PSICOLÓGICA http://sumapsicologica.konradlorenz.edu.co Resumen Por medio del presente estudio se busca analizar la capacidad predictiva de la inteligencia emocional medida tanto desde el modelo de habilidad (atención, claridad y reparación emocional) como desde un modelo mixto (intrapersonal, interpersonal, manejo del estrés y adaptabilidad). Esto, sobre cada una de las fuentes del apoyo social percibido (familiares, amigos y personas significativas), teniendo en cuenta el sexo y la edad de los adolescentes. La muestra estuvo compuesta por 1030 estudiantes de educación secundaria con edades entre 11 y 19 años residentes en la República Dominicana. Los resultados señalan que la inteligencia emocional predice la percepción del apoyo social en las muestras de ambos sexos, aunque entre las chicas el efecto explicativo es mayor que entre los varones. Se observa también que la capacidad predictiva es mayor en la adolescencia media. Estos datos refuerzan la necesidad de desarrollar la inteligencia emocional.

We report a first-principles description of the induced wake potential and density in real solids. The linear-response formalism is used to obtain the potential and density induced by an external charge penetrating through an inhomogeneous periodic system. The linear dynamical response of the system is evaluated in the random-phase approximation, by including the full band structure of the solid. The impact of the periodic crystalline potential is analyzed, and variations of the wake along different channels in Al and Si are investigated.Typeset using REVT E X