We study, using molecular dynamics techniques, how boundary conditions affect the process of fragmentation of finite, highly excited, Lennard-Jones systems. We analyze the behavior of the caloric curves (CC), the associated thermal response functions (TRF) and cluster mass distributions for constrained and unconstrained hot drops. It is shown that the resulting CC's for the constrained case differ from the one in the unconstrained case, mainly in the presence of a "vapor branch". This branch is absent in the free expanding case even at high energies . This effect is traced to the role played by the collective expansion motion. On the other hand, we found that the recently proposed characteristic features of a first order phase transition taking place in a finite isolated system, i.e. abnormally large kinetic energy fluctuations and a negative branch in the TRF, are present for the constrained (dilute) as well the unconstrained case. The microscopic origin of this behavior is also analyzed.

Successful text comprehension results in a coherent mental model of the situation being described. To achieve this, the reader has to infer certain information by connecting parts of the text to their prior knowledge. An important construct involved in this process is vocabulary knowledge, usually divided into breadth and depth. We conducted a meta-analysis on 23 studies, and explored the fit of five different models to establish an effect size of both dimensions of vocabulary on inference making, as well as its developmental trajectory in children aged 3-12. We found a significant and moderate effect of vocabulary knowledge of both modalities. Vocabulary type was not a significant moderator, but age was, meaning that there was a similar effect for both breadth and depth and that the strength of the correlations decreased with age. Heterogeneity was high overall, meaning that more moderators should be assessed in future studies.

El vocabulario se refiere al conocimiento acerca de las palabras que maneja y conoce una persona, y juega un rol importante en el desarrollo y la ejecución de gran cantidad de habilidades cognitivas. El objetivo de este estudio fue evaluar el tamaño del efecto del vocabulario en ambas modalidades, profundidad y amplitud, en las habilidades de resolución de problemas aritméticos. Con este propósito se realizó un meta-análisis sobre 16 estudios relacionados al tema. Se incluyeron estudios posteriores al año 2000, con niños entre 3 y 13 años y sin problemas neurológicos. Los resultados obtenidos mostraron un efecto moderado y significativo del vocabulario, tanto con respecto a la amplitud como a la profundidad del mismo, sobre la resolución de problemas aritméticos de tipo lingüístico. Los resultados también muestran un índice elevado de heterogeneidad, que puede ser explicado por las inconsistencias a la hora de evaluar los constructos.