Metalenses consist of an array of optical nanoantennas on a surface capable of manipulating the properties of an incoming light wavefront. Various flat optical components, such as polarizers, optical imaging encoders, tunable phase modulators and a retroreflector, have been demonstrated using a metalens design. An open issue, especially problematic for colour imaging and display applications, is the correction of chromatic aberration, an intrinsic effect originating from the specific resonance and limited working bandwidth of each nanoantenna. As a result, no metalens has demonstrated full-colour imaging in the visible wavelength. Here, we show a design and fabrication that consists of GaN-based integrated-resonant unit elements to achieve an achromatic metalens operating in the entire visible region in transmission mode. The focal length of our metalenses remains unchanged as the incident wavelength is varied from 400 to 660 nm, demonstrating complete elimination of chromatic aberration at about 49% bandwidth of the central working wavelength. The average efficiency of a metalens with a numerical aperture of 0.106 is about 40% over the whole visible spectrum. We also show some examples of full-colour imaging based on this design.

Among various flat optical devices, metasurfaces have presented their great ability in efficient manipulation of light fields and have been proposed for variety of devices with specific functionalities. However, due to the high phase dispersion of their building blocks, metasurfaces significantly suffer from large chromatic aberration. Here we propose a design principle to realize achromatic metasurface devices which successfully eliminate the chromatic aberration over a continuous wavelength region from 1200 to 1680 nm for circularly-polarized incidences in a reflection scheme. For this proof-of-concept, we demonstrate broadband achromatic metalenses (with the efficiency on the order of ∼12%) which are capable of focusing light with arbitrary wavelength at the same focal plane. A broadband achromatic gradient metasurface is also implemented, which is able to deflect wide-band light by the same angle. Through this approach, various flat achromatic devices that were previously impossible can be realized, which will allow innovation in full-color detection and imaging.

The family-centered preoperative ADVANCE preparation program is effective in the reduction of preoperative anxiety and improvement in postoperative outcomes.

No abstract

Under the conditions of this study, oral midazolam is more effective than either parental presence or no intervention for managing a child's and parent's anxiety during the preoperative period.

The development of two-dimensional metasurfaces has shown great potential in quantum-optical technologies because of the excellent flexibility in light-field manipulation. By integrating a metalens array with a nonlinear crystal, we demonstrate a 100-path spontaneous parametric down-conversion photon-pair source in a 10 × 10 array, which shows promise for high-dimensional entanglement and multiphoton-state generation. We demonstrate two-, three- and four-dimensional two-photon path entanglement with different phases encoded by metalenses with fidelities of 98.4, 96.6, and 95.0%, respectively. Furthermore, four-photon and six-photon generation is observed with high indistinguishability of photons generated from different metalenses. Our metalens-array–based quantum photon source is compact, stable, and controllable, indicating a new platform for integrated quantum devices.

PPIA in addition to 0.5 mg/kg oral midazolam has no additive effects in terms of reducing a child's anxiety. Parents who accompanied their children to the operating room, however, were less anxious and more satisfied.

Acupuncture has been used in China and other Asian countries for the past 3000 yr. Recently, this technique has been gaining increased popularity among physicians and patients in the United States. Even though acupuncture-induced analgesia is being used in many pain management programs in the United States, the mechanism of action remains unclear. Studies suggest that acupuncture and related techniques trigger a sequence of events that include the release of neurotransmitters, endogenous opioid-like substances, and activation of c-fos within the central nervous system. Recent developments in central nervous system imaging techniques allow scientists to better evaluate the chain of events that occur after acupuncture-induced stimulation. In this review article we examine current biophysiological and imaging studies that explore the mechanisms of acupuncture analgesia.