Recent results in quantum chaos and its applications to atomic nuclei

A survey of chaotic dynamics in atomic nuclei is presented, using on the one hand standard statistics of quantum chaos studies, and on the other a new approach based on time series analysis methods. The study of shell-model spectra in the pf shell shows that nuclear chaos is strongly isopin dependent and increases with excitation energy. On the other hand, it is found that chaotic quantum systems exhibit 1/f noise and regular systems exhibit 1/f(2) behaviour. It is shown that the time series approach can be used to calculate quite accurately the fraction of missing levels and the existence of mixed symmetries in experimental level spectra

Repair and stabilization in confined nanoscale systems - inorganic nanowires within single-walled carbon nanotubes

Repair is ubiquitous in biological systems, but rare in the inorganic world. We show that inorganic nanoscale systems can however possess remarkable repair and reconfiguring capabilities when subjected to extreme confinement. Confined crystallization inside single-walled carbon nanotube (SWCNT) templates is known to produce the narrowest inorganic nanowires, but little is known about the potential for repair of such nanowires once crystallized, and what can drive it. Here inorganic nanowires encapsulated within SWCNTs were seen by high-resolution transmission electron microscopy to adjust to changes in their nanotube template through atomic rearrangement at room temperature. These observations highlight nanowire repair processes, supported by theoretical modeling, that are consistent with atomic migration at fractured, ionic ends of the nanowires encouraged by long-range force fields, as well as release-blocking mechanisms where nanowire atoms bind to nanotube walls to stabilize the ruptured nanotube and allow the nanowire to reform. Such principles can inform the design of nanoscale systems with enhanced resilience. © 2012 Tsinghua University Press and Springer-Verlag Berlin Heidelberg