The influence of a short-term mindfulness meditation intervention on emotion and visual attention

It has been suggested that mindfulness meditation (MM) improves psychological wellbeing via the focusing and broadening of attention. Whilst studies show that short term MM interventions can improve focused attention there is little evidence to support the broadening of attention. The current study investigated the influence of a short-term MM intervention on emotion and the scope of visual attention. Seventy participants completed a global-local processing task separated into three blocks of trials, with a ten minute break between each one. During the breaks a MM group engaged in a breath counting task and a control group engaged in a task of their choosing. Response times to global and local targets and a measure of self-reported emotional affect were recorded for each block. Mindfulness had no impact on attention however both positive and negative affect decreased for the MM group across the course of the experiment. The results suggest that MM can reduce the focus on negative (and positive) thoughts, indicating possible changes to focused attention, yet a short-term intervention is not sufficient to broaden attentio

Red spectral shift and enhanced quantum efficiency in phonon-free photoluminescence from silicon nanocrystals

Crystalline silicon is the most important semiconductor material in the electronics industry. However, silicon has poor optical properties because of its indirect bandgap, which prevents the efficient emission and absorption of light. The energy structure of silicon can be manipulated through quantum confinement effects, and the excitonic emission from silicon nanocrystals increases in intensity and shifts to shorter wavelengths (a blueshift) as the size of the nanocrystals is reduced. Here we report experimental evidence for a short-lived visible band in the photoluminescence spectrum of silicon nanocrystals that increases in intensity and shifts to longer wavelengths (a redshift) with smaller nanocrystal sizes. This higher intensity indicates an increased quantum efficiency, which for 2.5-nm-diameter nanocrystals is enhanced by three orders of magnitude compared to bulk silicon. We assign this band to the radiative recombination of non-equilibrium electron-hole pairs in a process that does not involve phonons. © 2010 Macmillan Publishers Limited. All rights reserved