The aim of this study was a preliminary characterization (mineralogical, chemical, textural) of flotation wastes - which are the by-product of zinc-lead concentrate extraction - from the standpoint of their further prospective (experimental) use as sorbents of acid gases (SO2 and CO2). The...

This paper studies the effects of information and communication technologies (ICT) in the school environment on educational achievement. To quantify these effects, the impact is evaluated of a project run by the municipality of Guayaquil, Ecuador, which provides computer-aided instruction in...

How do markets spread risk when events are unknown or unknowable and where not anticipated in an insurance contract? While the policyholder can 'hold up' the insurer for extra contractual payments, the continuing gains from trade on a single contract are often too small to yield useful coverage....