Un análisis de las cartas al director en diarios de referencia internacional

El artículo analiza la sección de cartas al director de ocho diarios de referencia mundial (The New York Times, The Times, The Guardian, Le Monde, Le Figaro, El País, ABC y La Vanguardia) a partir de una clasificación de las cartas basada en el tipo de relación que mantiene el lector con el medio y con el resto de lectores. Los resultados muestran que los diarios anglosajones publican más cartas y les dedican más espacio que los diarios franceses o los diarios españoles. El análisis también resuelve el tiempo de permanencia de un asunto en la sección de cartas y cuáles son los aspectos de la vida recogidos mayoritariamente en las secciones de cartas al director de los diarios de referencia. El artículo desgrana el perfil de los redactores de cartas y el sentido que le dan los diarios de calidad a este tipo de participación de los lectores

Lattice dynamics and phonon softening in Ni-Mn-Al Heusler alloys

Inelastic and elastic neutron scattering have been used to study a single crystal of the Ni$_{54}$Mn$_{23}$Al$_{23}$ Heusler alloy over a broad temperature range. The paper reports the first experimental determination of the low-lying phonon dispersion curves for this alloy system. We find that the frequencies of the TA$_2$ modes are relatively low. This branch exhibits an anomaly (dip) at a wave number $\xi_{0} ={1/3}\approx 0.33$, which softens with decreasing temperature. Associated with this anomalous dip at $\xi_{0}$, an elastic central peak scattering is also present. We have also observed satellites due to the magnetic ordering.Comment: 6 pages, 6 figures. Accepted for publication in the Physical Review

Weakly encoded memories due to acute sleep restriction can be rescued after one night of recovery sleep

Sleep is thought to play a complementary role in human memory processing: sleep loss impairs the formation of new memories during the following awake period and, conversely, normal sleep promotes the strengthening of the already encoded memories. However, whether sleep can strengthen deteriorated memories caused by insufficient sleep remains unknown. Here, we showed that sleep restriction in a group of participants caused a reduction in the stability of EEG activity patterns across multiple encoding of the same event during awake, compared with a group of participants that got a full night's sleep. The decrease of neural stability patterns in the sleep-restricted group was associated with higher slow oscillation-spindle coupling during a subsequent night of normal sleep duration, thereby suggesting the instantiation of restorative neural mechanisms adaptively supporting cognition and memory. Importantly, upon awaking, the two groups of participants showed equivalent retrieval accuracy supported by subtle differences in the reinstatement of encoding-related activity: it was longer lasting in sleep-restricted individuals than in controls. In addition, sustained reinstatement over time was associated with increased coupling between spindles and slow oscillations. Taken together, these results suggest that the strength of prior encoding might be an important moderator of memory consolidation during sleep. Supporting this view, spindles nesting in the slow oscillation increased the probability of correct recognition only for weakly encoded memories. Current results demonstrate the benefit that a full night's sleep can induce to impaired memory traces caused by an inadequate amount of sleep