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The frame of a string instrument is subject to a large tension force when the strings are installed. Intuitively, one might expect that the frame would be stiffened by the strings. Experimental data and a theoretical analysis are presented to show that this is not generally the case. An archer's bow is much stiffer when it is strung, but a tennis racquet is softened when the strings are added. As a result, the mode frequencies for transverse vibrations increase for a bow and decrease for a racquet when the strings are added. The effect of the strings depends on the extent to which the frame is bent at equilibrium. [ABSTRACT FROM AUTHOR]

Electronic band structures of single-walled silicon carbide nanotubes are studied under uniaxial strain using first principles calculations. The band structure can be tuned by mechanical strain in a wide energy range. The band gap decreases with uniaxial tensile strain, but initially increases with uniaxial compressive strain and then decreases with further increases in compressive strain. These results may provide a way to tune the electronic structures of silicon carbide nanotubes, which may have promising applications in building nanodevices. [ABSTRACT FROM AUTHOR]