Noncircular System Research Articles

Chiral p-wave superconducting states in mesoscopic noncircular systems at zero external magnetic field

Using Bogoliubov-de Gennes formalism, the chiral order parameters in mesoscopic p-wave superconducting noncircular systems are investigated in the absence of applied magnetic field. For the perfect square or rectangular sample, a single-domain-wall state tends to emerge, accompanied by a vertical or horizontal domain wall separating the regions with different chiralities. This type of domain walls can be effectively tuned by temperature and the aspect ratio of samples, and the multi-domain-wall state containing two domain walls can be obtained. Moreover, for a p-wave square loop with a centered hole, the diagonal-symmetric mode for orders is presented, leading to four domain walls placed at the center of four arms of the loop. In particular, several peculiar domain-wall states may show up in the asymmetric square loop system with an off-centered hole.

Intermittent superconductivity and unconventional vortex configurations in nanoscale superconducting noncircular systems

The flux-dependent evolution of vortex states in nanoscale superconducting noncircular systems is investigated based on the Bogoliubov-de Gennes theory. For a superconductor with the coherence length comparable to the Fermi wavelength, the spatial variations of the superconducting order parameter are very sensitive to the finite size of the sample. With increasing the applied flux, the superconducting state and the normal state can alternately appear in small squares, and a remarkable intermittent superconducting behavior for the ground-state transition is found. Moreover, when the square size is enlarged, the asymmetric single-vortex and multivortex states as well as the vortex-antivortex pairs can emerge as the metastable or ground states, arising from the effect of strong quantum confinement.

Cycling with noncircular chainring system changes the three-dimensional kinematics of the lower limbs

This study investigated the three-dimensional (3-D) pedaling kinematics using a noncircular chainring system and a conventional system. Five cyclists pedaled at their preferred cadence at a workload of 300 W using two crank systems. Flexion/extension of the hip, knee and ankle as well as shank rotation, foot adduction/abduction, and pedal angle were measured. Joint range of motion (ROM) and angular displacements were compared between the systems. Sagittal plane ROM was significantly greater (P < 0.05) at the hip (noncircular system = 39 ± 3°; conventional system = 34 ± 4°) the knee (noncircular system = 69 ± 4°; conventional system = 57 ± 10°), and ankle (noncircular system = 21 ± 2°; conventional system = 19 ± 4°) resulting in greater pedal ROM (noncircular system = 43 ± 3°; conventional system = 37 ± 5°) while using the noncircular system. Shank rotation ROM was significantly lower (P < 0.05) while using the noncircular chainring (noncircular system = 10 ± 1°; conventional system = 14 ± 1°). These results support a significant effect of the noncircular chainring system on pedaling kinematics during submaximal exercise.