Peer effects identified through social networks. Evidence from Uruguayan schools

This paper provides evidence on peer effects in educational achievement exploiting for the first time a unique data set on social networks within primary schools in Uruguay. The relevance of peer effects in education is still largely debated due to the identification challenges that the study of social interactions poses. I adopt a recently developed identification method that exploits detailed information on social networks, i.e. individual-specific peer groups. This method enables me to disentangle endogenous effects from contextual effects via instrumental variables that emerge naturally from the network structure. Correlated effects are controlled, to some extent, by classroom fixed effects. I find significant endogenous effects in standardized tests for reading and math. A one standard deviation increase in peers’ test score increases the individual’s test score by 40% of a standard deviation. This magnitude is comparable to the effect of having a mother that completed college. By means of a simulation I illustrate that when schools are stratified by socioeconomic status peer effects may operate as amplifiers of educational inequalities.

Estimation of cement thermal properties through the three-phase model with application to geothermal wells

Geothermal energy has been used by mankind since ancient times. Given the limited geographical distribution of the most favorable resources, exploration efforts have more recently focused on unconventional geothermal systems targeting greater depths to reach sufficient temperatures. In these systems, geothermal well performance relies on efficient heat transfer between the working fluid, which is pumped from surface, and the underground rock. Most of the wells designed for such environments require that the casing strings used throughout the well construction process be cemented in place. The overall heat transfer around the wellbore may be optimized through accurate selection of cement recipes. This paper presents the application of a three-phase analytical model to estimate the cement thermal properties. The results show that cement recipes can be designed to enhance or minimize heat transfer around wellbore, extending the application of geothermal exploitation