Vanishing Cosmological Constant in Modified Gauss-Bonnet Gravity with Conformal Anomaly

We consider dark energy cosmology in a de Sitter universe filled with quantum conformal matter. Our model represents a Gauss-Bonnet model of gravity with contributions from quantum effects. To the General Relativity action an arbitrary function of the GB invariant, f(G), is added, and taking into account quantum effects from matter the cosmological constant is studied. For the considered model the conditions for a vanishing cosmological constant are considered. Creation of a de Sitter universe by quantum effects in a GB modified gravity is discussed.Comment: 8 pages latex, 1 figure. To appear in Int. J. Mod. Phys.

Análisis de la estructura del sector agua en Nuevo León y sus relaciones intersectoriales : (segunda parte)

En este estudio se construye un modelo regional de insumoproducto para el estado de Nuevo León, el cual se caracteriza por sufrir frecuente escasez de agua. El modelo que se propone enfatiza las interrelaciones económicas del sector agua con los demás sectores de la economía

Análisis de la estructura del sector agua en Nuevo León y sus relaciones intersectoriales : (primera parte)

El estudio traza los efectos de la oferta de agua en el producto, ingreso y empleo del estado de Nuevo León, entidad que se localiza en el noreste de México. Para ello se construye un modelo de insumo-producto regional con énfasis en el sector agua. En primer lugar, se separa el agua del sector de electricidad y gas, y segundo, se le desagrega en cuatro categorías: agua potable, agua subterránea, aguas negras y aguas residuales. Los resultados sugieren que el sector en cuestión, particularmente la provisión de agua potable, tiene impactos económicos significativos sobre el resto de la economía, mismos que actualmente son subestimados por la falta de desagregación.This study traces the effect of water supply on output, employment and labor income in the Mexican state of Nuevo Leon. For this purpose, an input-output model with emphasis on the water sector is constructed. Firstly, water is isolated from electricity and gas as these utilities are recorded as a single sector. Secondly, water is disaggregated into four categories: drinking water, aquifers, sewage and treated wastewater. The results suggest that the water sector, particularly the provision of drinking water, has significant knock-on effects on the rest of the economy, which currently are sub estimated due to the lack of disaggregation

Análisis de la estructura del sector agua en Nuevo León y sus relaciones intersectoriales

This study traces the effect of water supply on output, employment and labor income in the Mexican state of Nuevo Leon. For this purpose, an input-output model with emphasis on the water sector is constructed. Firstly, water is isolated from electricity and gas as these utilities are recorded as a single sector. Secondly, water is disaggregated into four categories: drinking water, aquifers, sewage and treated wastewater. The results suggest that the water sector, particularly the provision of drinking water, has significant knock-on effects on the rest of the economy, which currently are sub estimated due to the lack of desegregation.