Negative Ions in Space

Until a decade ago, the only anion observed to play a prominent role in astrophysics was H–. The bound–free transitions in H– dominate the visible opacity in stars with photospheric temperatures less than 7000 K, including the Sun. The H– anion is also believed to have been critical to the formation of molecular hydrogen in the very early evolution of the Universe. Once H₂ formed, about 500 000 years after the Big Bang, the expanding gas was able to lose internal gravitational energy and collapse to form stellar objects and “protogalaxies”, allowing the creation of heavier elements such as C, N, and O through nucleosynthesis. Although astronomers had considered some processes through which anions might form in interstellar clouds and circumstellar envelopes, including the important role that polycyclic aromatic hydrocarbons might play in this, it was the detection in 2006 of rotational line emission from C₆H– that galvanized a systematic study of the abundance, distribution, and chemistry of anions in the interstellar medium. In 2007, the Cassini mission reported the unexpected detection of anions with mass-to-charge ratios of up to ˜10 000 in the upper atmosphere of Titan; this observation likewise instigated the study of fundamental chemical processes involving negative ions among planetary scientists. In this article, we review the observations of anions in interstellar clouds, circumstellar envelopes, Titan, and cometary comae. We then discuss a number of processes by which anions can be created and destroyed in these environments. The derivation of accurate rate coefficients for these processes is an essential input for the chemical kinetic modeling that is necessary to fully extract physics from the observational data. We discuss such models, along with their successes and failings, and finish with an outlook on the future

Lateralization of the cerebral network of inhibition in children before and after cognitive training

Inhibitory control (IC) plays a critical role in cognitive and socio-emotional development. IC relies on a lateralized cortico-subcortical brain network including the inferior frontal cortex, anterior parts of insula, anterior cingulate cortex, caudate nucleus and putamen. Brain asymmetries play a critical role for IC efficiency. In parallel to age-related changes, IC can be improved following training. The aim of this study was to (1) assess the lateralization of IC network in children (N = 60, 9–10 y.o.) and (2) examine possible changes in neural asymmetry of this network from anatomical (structural MRI) and functional (resting-state fMRI) levels after 5-week computerized IC vs. active control (AC) training. We observed that IC training, but not AC training, led to a leftward lateralization of the putamen anatomy, similarly to what is observed in adults, supporting that training could accelerate the maturation of this structure