Evaluating effectiveness and safety of combined percutaneous transhepatic gallbladder drainage and laparoscopic cholecystectomy in acute cholecystitis patients: Meta-analysis.

Background: Acute cholecystitis (AC) is a common disease in general surgery. Laparoscopic cholecystectomy (LC) is widely recognized as the "gold standard" surgical procedure for treating AC. For low-risk patients without complications, LC is the recommended treatment plan, but there is still controversy regarding the treatment strategy for moderate AC patients, which relies more on the surgeon's experience and the medical platform of the visiting unit.

Optical non-reciprocity induced by asymmetrical dispersion of Tamm plasmon polaritons in terahertz magnetoplasmonic crystals.

Nonreciprocal light phenomena, including one-way wave propagation along an interface and one-way optical tunneling, are presented at terahertz frequencies in a system of magnetically controlled multi-layered structure. By varying the surface termination and the surrounding medium, it is found that the nonreciprocal bound or radiative Tamm plasmon polartions can be supported, manipulated, and well excited. Two different types of contributions to the non-reciprocity are analyzed, including the direct effect of magnetization-dependent surface terminating layer as well as violation of the periodicity in truncated multi-layered systems.

Electrical tunability due to coalescence of exceptional points in parity-time symmetric waveguides.

We demonstrate theoretically the electric tunability due to the coalescence of exceptional points in PT-symmetric waveguides bounded by imperfect conductive layers. Owing to the competition effect of multimode interaction, multiple exceptional points and PT phase transitions could be attained in such a simple system, and their occurrences are strongly dependent on the boundary conductive layers. When the conductive layers become very thin, it is found that the oblique transmittance and reflectance of the same system can be tuned between zero and one by a small change in the carrier density.

Broadband Focusing Acoustic Lens Based on Fractal Metamaterials.

Acoustic metamaterials are artificial structures which can manipulate sound waves through their unconventional effective properties. Different from the locally resonant elements proposed in earlier studies, we propose an alternate route to realize acoustic metamaterials with both low loss and large refractive indices. We describe a new kind of acoustic metamaterial element with the fractal geometry.

One-way optical tunneling induced by nonreciprocal dispersion of Tamm states in magnetophotonic crystals.

We show that optical Tamm states (OTSs) with nonreciprocal dispersion can be formed at the boundary separating two different magnetophotonic crystals magnetized in the Voigt geometry. At the frequencies of the Tamm states, one-way optical tunneling can be achieved. The nonreciprocity features of OTSs originate from the simultaneous violation of reciprocity, time-reversal, and all related spatial symmetries in the system.

Super-resolution image transfer by a vortex-like metamaterial.

We propose a vortex-like metamaterial device that is capable of transferring image along a spiral route without losing subwavelength information of the image. The super-resolution image can be guided and magnified at the same time with one single design. Our design may provide insights in manipulating super-resolution image in a more flexible manner.

Subwavelength image manipulation through an oblique layered system.

We show in this work an oblique layered system that is capable of manipulating two dimensional subwavelength images. Through properly designed planar layered system, we demonstrate analytically that lateral image shift could be achieved with subwavelength resolution, due to the asymmetry of the dispersion curve of constant frequency. Further, image rotation with arbitrary angle, as well as image magnification could be generated through a concentric geometry of the alternating layered system.