Evidence for multiple rhythmic skills

Rhythms, or patterns in time, play a vital role in both speech and music. Proficiency in a number of rhythm skills has been linked to language ability, suggesting that certain rhythmic processes in music and language rely on overlapping resources. However, a lack of understanding about how rhythm skills relate to each other has impeded progress in understanding how language relies on rhythm processing. In particular, it is unknown whether all rhythm skills are linked together, forming a single broad rhythmic competence, or whether there are multiple dissociable rhythm skills. We hypothesized that beat tapping and rhythm memory/sequencing form two separate clusters of rhythm skills. This hypothesis was tested with a battery of two beat tapping and two rhythm memory tests. Here we show that tapping to a metronome and the ability to adjust to a changing tempo while tapping to a metronome are related skills. The ability to remember rhythms and to drum along to repeating rhythmic sequences are also related. However, we found no relationship between beat tapping skills and rhythm memory skills. Thus, beat tapping and rhythm memory are dissociable rhythmic aptitudes. This discovery may inform future research disambiguating how distinct rhythm competencies track with specific language functions

Plasmonic chiroptical response of silver nanoparticles interacting with chiral supramolecular assemblies

Silver nanoparticles were prepared in aqueous solutions of chiral supramolecular structures made of chiral molecular building blocks. While these chiral molecules display negligible circular dichroism (CD) as isolated molecules, their stacking produced a significant CD response at room temperature, which could be eliminated by heating to 80 degrees C due to disordering of the stacks. The chiral stack-plasmon coupling has induced CD at the surface plasmon resonance absorption band of the silver nanoparticles. Switching between two plasmonic CD induction mechanisms was observed: (1) Small Ag nanoparticles coated with large molecular stacks, where the induced plasmonic CD decayed together with the UV molecular CD bands on heating the solution, indicating some type of electromagnetic or dipole coupling mechanism. (2) Larger Ag nanoparticles coated with about a monolayer of molecules exhibited induced plasmonic CD that was temperature-independent. In this case it is estimated that the low chiroptical response of a molecular monolayer is incapable of inducing such a large chiroptical effect, and a model calculation shows that the plasmonic CD response may be the result of a slight chiral shape distortion of the silver nanoparticles