Sobre la movilidad de la halita, la silvina y las arcillas durante las deformaciones tectónicas

En los yacimientos de Cardona, Balsareny y Suria (Barcelona) puede observarse que cuanto mayor sea la complejidad tectónica, menor es la cantidad de arcillas que acompañan a los haluros. Ello es debido a que, al producirse las deformaciones tectónicas, la movilidad de las sales es superior y los materiales arcillosos no pueden seguirlas en sus desplazamiento. El hecho queda explicado por las siguientes particularidades cristaloquímicas. 1) Halita y silvina son deformables según todas las direcciones debido a: a) las partículas se hallan unidas por enlaces iónico, no dirigido; b) anión y catión se hallan en igual cantidad, debiéndose cumplir únicamente que cada catión esté rodeado de aniones y viceversa. 2) Por el contrario, los minerales de la arcilla son deformables según un sólo plano, debido a su estructura laminar

Estudio de unos cristales escalenoédricos de calcita procedentes de la Plana de Vic (Barcelona)

Se estudian las relaciones entre el hábito escalenoédrico de unos cristales de calcita procedentes de la Plana de Vic (Barcelona) y la presencia en los mismos de Mn procedentes de la roca sustrato

Risk Management Plans: are they a tool for improving drug safety?

PURPOSE: In 2005, new European legislation authorised Regulatory Agencies to require drug companies to submit a risk management plan (RMP) comprising detailed commitments for post-marketing pharmacovigilance. The aim of the study is to describe the characteristics of RMP for 15 drugs approved by the European Medicines Agency (EMA) and their impact on post-marketing safety issues. METHODS: Of the 90 new Chemical Entities approved through a centralised procedure by the EMA during 2006 and 2007, 15 of them were selected and their safety aspects and relative RMPs analysed. All post-marketing communications released for safety reasons related to these drugs were also considered. RESULTS: A total of 157 safety specifications were established for the drugs assessed. Risk minimisation activities were foreseen for 5 drugs as training activities. Post-marketing safety issues emerged for 12 of them, leading to 39 type II variations in Summary of Product Characteristics (SPC). Nearly half of such variations, 19 (49%), concerned safety aspects not envisaged by the RMPs. Besides this, 9 Safety Communications were published for 6 out of 15 drugs assessed. CONCLUSION: The present study reveals several critical points on the way RMPs have been implemented. Several activities proposed by the RMPs do not appear to be adequate in dealing with the potential risks of drugs. Poor communication of risk to practitioners and to the public, and above all limited transparency for the total assessment of risk, seem to transform RMPs into a tool to reassure the public when inadequately evaluated drugs are granted premature marketing authorisation