Ultrathin metasurface on a 100 nm-thick dielectric membrane absorbs infrared rays.

Flat optics based on metasurfaces produce unprecedented two-dimensional planar optical elements that cannot be developed with naturally occurring materials. However, it remains to be shown whether metasurfaces on ultrathin dielectric membranes can be adopted in a broad range of optical elements as flat optics. Here we demonstrate that a fabricated ultrathin metasurface composed of double-sided metal structures on a 100 nm-thick SiNx membrane absorbs infrared rays with a high absorptance of 97.

Valid Indicators for Predicting Falls in Community-Dwelling Older Adults Under Ongoing Exercise Intervention to Prevent Care Requirement.

Physical exercise interventions to prevent falls for older adults at risk of falling are widespread in many countries; however, there is insufficient knowledge of the impact of long-term exercise on the fall discriminating ability of existing fall-prediction indicators. This study measured physical and cognitive indicators of the fall risk, including the timed up and go (TUG), walking speed (WS), and plantar tactile threshold (PTT), in 124 community-dwelling older adults with care needs who were continuing an exercise program. Logistic regression analyses were used to determine factors associated with falls in the 87 participants who could adhere to the exercise continuously for 12 months.

Reflectionless metasurface with high refractive index in the terahertz waveband.

Terahertz flat optics is a design concept for replacing conventional three-dimensional bulky optical components with two-dimensional ultra-thin optical components. However, high refractive index materials suitable for flat optics are frequently subject to high Fresnel reflections due to the cumbersome control of the relative permeability it requires. Here we experimentally demonstrate a reflectionless metasurface with a high refractive index of 5.

Reflectionless zero refractive index metasurface in the terahertz waveband.

Zero refractive index materials behave electromagnetically as single points despite the finite dimensions because a propagating electromagnetic wave passes with an infinite phase velocity. However, the composition of naturally occurring materials cannot produce a zero refractive index material because any effect of both of the dielectric and magnetic properties would have to vanish (be near zero). In this report, we demonstrate a zero refractive index metasurface with a refractive index of 0.