El trabajo práctico en la enseñanza de las ciencias : una revisión

This article is a review about the effectiveness of practicals in science education at the secondary and tertiary levels. Through more than one hundred references, the authors conclude solid arguments have not been provided to justify the great deal of material and human resources needed for the implementation of this educational tool. In spite of these disappointing findings, the authors do not deny the central role of practicals in science education, and they justify these negative results by invoking the great complexity of the subject, the ambiguity that surrounds the term «practicals», and an unsuitable methodology that researchers use to measure their effectiveness. Finally, some plausible solutions to the problem are suggested, such as the characterisation of the educational objectives of practicals, or the use of a qualitative evaluation methodology

Spin phonon coupling in frustrated magnet CdCr2_2O4_4

The infrared phonon spectrum of the spinel CdCr2O4 is measured as a function temperature from 6 K to 300K. The triply degenerate Cr phonons soften in the paramagnetic phase as temperature is lowered below 100 K and then split into a singlet and doublet in the low T antiferromagnetic phase which is tetragonally distorted to relieve the geometric frustration in the pyrochlore lattice of Cr$^{3+}$ ions. The phonon splitting is inconsistent with the simple increase (decrease) in the force constants due to deceasing (increasing) bond lengths in the tetragonal phase. Rather they correspond to changes in the force constants due to the magnetic order in the antiferromagnetic state. The phonon splitting in this system is opposite of that observed earlier in ZnCr2O4 as predicted by theory. The magnitude of the splitting gives a measure of the spin phonon coupling strength which is smaller than in the case of ZnCr2O4.Comment: 4.2 pages, 4 figures, 1 reference added, submmite

Money and Inflation in an Inflation-Tageting Regime

This work describes the role of money in the current inflation-targeting framework in Chile, in particular given the large recent annual increase in M1A. From a conceptual standpoint, it analyzes the relationship between money growth and inflation, as well as the interpretation of movements in monetary aggregates. Empirically, the article evaluates the informational content of money as an indicator of inflationary pressures in Chile, and examines whether the recent evolution of M1A is consistent with money demand fundamentals. The evidence indicates that the recent trajectory of money does not represent a material risk to the achievement of the inflation target.

Dinero e Inflación en el Marco de Metas de Inflación

This work describes the role of money in the current inflation-targeting framework in Chile, in particular given the large recent annual increase of M1A. From a conceptual point of view, we analyze the relationship between money growth and inflation, as well as the interpretation of the movements in monetary aggregates. Empirically, we evaluate the informational content of money as an indicator of inflationary pressures in Chile, as well as whether the recent evolution of M1A is consistent with money demand fundamentals. The evidence indicates that the recent trajectory of money does not represent a relevant risk to the achievement of the inflation target.