Autofocusing of ring Airy beams embedded with off-axial vortex singularities.

We report the autofocusing behaviors of ring Airy beams (RABs) embedded with two kinds of off-axial vortex singularities. The influences of embedded positions and topological charges of point and r vortices on the autofocusing dynamic are numerically and experimentally investigated. The results show that, for the first-order vortex, the embedded position significantly affects the focal field, and once the singularity is located on the main ring of RAB, the symmetric Bessel profile of the focal field will be broken, otherwise the Bessel-like focus can self-heal at the focal plane. However, for the higher-order vortex embedded near the main ring, it will split into several fundamental vortices and then separate with each other along the radial direction under the interaction with the RAB background. Our results hold potential for the practical application of RABs in the atmosphere and other propagation systems with perturbation and even singularities.

Both flow-mediated vasodilation procedures and acute exercise improve endothelial function in obese young men.

Obesity is associated with impaired endothelial function assessed as flow-mediated vasodilation (FMD), the procedure of which involves transient brachial artery occlusion and following reactive hyperemia. Acute aerobic exercise can improve FMD. This study examined the effects of repeated FMD procedures and acute aerobic exercise on FMD in obese young men. Upper arm cuff inflation of 200 mmHg for 5 min and subsequent deflation was induced at 0, 1 and 2 h to examine effects of repeated FMD procedures on FMD in obese subjects, as well as in lean controls. To observe the combined effects of FMD procedures and acute exercise on FMD in obese subjects, 45 min moderate exercise was performed immediately after FMD procedure at 0 h, with the procedure repeated at 1 and 2 h. The results showed that, after repeated FMD procedures, FMD in obese subjects increased from 5.9 +/- 4.0% to 6.5 +/- 3.2% and 8.4 +/- 2.8% (P = 0.017), whereas FMD demonstrated no changes in lean controls (P = 0.90). After repeated FMD procedures and exercise, FMD in the obese subjects increased from 7.3 +/- 3.5% to 9.5 +/- 4.0% and 11.0 +/- 4.3% (P = 0.0004). The present findings demonstrate that both repeated FMD procedures and acute aerobic exercise improve FMD in obese subjects.