First-principles simulations of lithium melting: stability of the bcc phase close to melting.

We report large-scale first-principles simulations of melting of four different phases of Li at pressures ranging from 0 to 50 GPa. We find excellent agreement with existing experimental data at low pressures, and confirm that above 10 GPa the melting line develops a negative slope, in parallel to what occurs for Na at 30 GPa. Surprisingly, our results indicate that the melting temperature of the bcc phase is always higher than that of fcc Li, suggesting the intriguing possibility of the existence of a narrow field of bcc stability separating the fcc and liquid phases, as predicted by Alexander and McTague [Phys. Rev. Lett. 41, 702 (1978)].

Enhanced Friedel structure and proton pairing in dense solid hydrogen.

The mechanism of proton pairing in dense solid hydrogen, and its progression with density, are both studied using effective potentials between protons which include electronic response up to quadratic terms. For high pressures nonlinear effects originating with different pairs are crucial in establishing the net attraction within a given pair, and in this picture Friedel oscillations are considerably enhanced by quadratic response, subsequently playing a very important role in the overall pairing. Calculated vibron frequencies also show substantial agreement with experiment, reflecting at the same time significant changes in the physical character of the pairing itself.

La psicología aplicada al apoyo e intervención de las personas / The psychology applied to the support and intervention of people with multiple sclerosis

El objetivo del estudio realizado en la Asociación de Esclerosis Múltiple de Vizcaya fue demostrar cómo la terapia grupal en pacientes con esclerosis múltiple era eficaz para disminuir los niveles de ansiedad y depresión, frecuentemente elevados en estos pacientes. Primeramente se seleccionó a los sujetos que iban a participar en el grupo de apoyo y los del grupo control. Posteriormente en una entrevista individual se les administraron la Escala Hamilton de Ansiedad y el Inventario de Depresión de Beck. Se utilizó un diseño paramétrico experimental con grupo control y medidas pre y postratamiento. Los hallazgos principales del estudio fueron que tanto los niveles de ansiedad como los de depresión disminuyeron considerablemente en las personas que habían participado en el grupo de apoyo y no así los del grupo control. (AU)