Analytic solution of the algebraic equation associated to the Ricci tensor in extended Palatini gravity

In this work we discuss the exact solution to the algebraic equation associated to the Ricci tensor in the quadratic $f(R,Q)$ extension of Palatini gravity. We show that an exact solution always exists, and in the general case it can be found by a simple matrix diagonalization. Furthermore, the general implications of the solution are analysed in detail, including the generation of an effective cosmological constant, and the recovery of the $f(R)$ and $f(Q)$ theories as particular cases in their corresponding limit. In addition, it is proposed a power series expansion of the solution which is successfully applied to the case of the electromagnetic field. We show that this power series expansion may be useful to deal perturbatively with some problems in the context of Palatini gravity.Comment: arXiv admin note: text overlap with arXiv:1101.3864, arXiv:1306.6537, arXiv:1112.2223 by other author

The social costs of crime in Mexico city and suburban areas

In this paper we measure social costs of crime, following two approaches. First, estimate costs of homicides, at the National level in 1997, under different assumptions about lost wages. When assuming profiles differ over the life cycle, the costs amount from .03 to .6 percent of GDP, depending on the discount factor. Second, we take into consideration other types of crime to estimate social costs of crime in Mexico City. We found costs approximate 3.6 percent of the City's GDP, but consider this figure a lower bound. Further data including costs borne by non-victims would be most helpful for further research in this field.

Productivity and R&D sources in manufacturing and service firms in Catalonia: a regional approach

This paper draws on a sample of innovative Catalan firms to identify the effects of the two main sources of innovation —internal R&D and external R&D acquisition— on productivity in the manufacturing and service industries. The sample comprises a 3,267 firms from the CIS-4 for the years 2002-2004. We compare empirical results when applying usual OLS and quantile regression techniques. Our results suggest the different patterns attributable to the two sources of innovation as we move up from lower to higher conditional quantiles. First, the effect of the marginal effect of internal R&D on productivity in both sectors decreased as we moved up to higher productivity levels. Second, the marginal effect of external R&D acquisition increased as we moved up to higher productivity levels, especially in high-tech manufacturing industries. Our empirical results suggest that the link between internal and external R&D is complex, varying between firms’ productivity levels and between industries.

The Role of Maternal Cognitive Ability in Child Health

The literature on child health suggests mother`s schooling is a key determinant of child health. Little is known of how other sources of maternal human capital contribute to her children`s health. This paper investigates the differential returns on child health of three sources of maternal human capital: schooling, cognitive ability and childhood background. Conditional on schooling and mother`s height, we first analyze the effect of maternal cognitive ability on her children`s health. Next, we relax the assumption of mother`s schooling and reasoning ability as predetermined variables and study the extent to which both returns reflect observed mother`s childhood endowments. We conclude by investigating the importance of mother`s schooling and cognitive ability in enhancing her offspring`s health during first-time motherhood. Results show maternal cognitive ability is an important factor in improving her children`s health. We find these returns robust to the inclusion of mother`s observed childhood endowments. However, estimates of mother`s schooling drop by 30 percent when we control for these variables. This suggests that unlike mother`s schooling, maternal returns to cognitive ability on child health are less likely to reflect mother`s childhood background. Finally, we find maternal reasoning ability to be an important factor in improving her children`s health in first-time motherhood. Our analysis is based on information gathered in the Mexican Family Life Survey (MxFLS-1), which administered Raven`s Colored Progressive Matrices, and collected anthropometric outcomes. Our results focus on child height-for-age (0-17 years) z-scores as long-run health outcomes.