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A fiber-optic acoustic pressure sensor based on a large-area nanolayer silver diaphragm is demonstrated with a high dynamic pressure sensitivity of 160  nm/Pa at 4 kHz frequency. The sensor exhibits a noise limited detectable pressure level of 14.5  μPa/Hz(1/2). Its high dynamic pressure sensitivity and simple fabrication process make it an attractive tool for acoustic sensing and photo-acoustic spectroscopy.

A compact all-fiber plasmonic Airy-like beam generator is demonstrated. A single slit and a 1D groove array were fabricated by focused ion beam milling on the gold deposited end facet of a single-mode optical fiber. The single slit excites the surface plasmonic polaritons (SPPs), which are decoupled into free space by the groove array. The phase of decoupling SPPs is adjusted by the grooves position. Experimental generation of the single Airy-like beam has good consistency with theoretical predictions. The transverse acceleration and nondiffraction properties are observed. The interference of double Airy-like beams in the free space is also analyzed. The presented plasmonic Airy-like beam generator is of importance to realize all-fiber optical trapping, beam shaping, and fiber integrated devices.

Unlabelled: The management of amyelic thoracolumbar burst fractures remains controversial. In this study, we compared the clinical efficacy of percutaneous kyphoplasty (PKP) and short-segment pedicle instrumentation (SSPI). Twenty-three patients were treated with PKP, and 25 patients with SSPI. They all presented with Type A3 amyelic thoracolumbar fractures. Clinical outcomes were evaluated by a Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) preoperatively, postoperatively, and at two years follow-up. Radiographic data including the anterior and posterior vertebral body height, kyphotic angle, as well as spinal canal compromise was also evaluated. The patients in both groups were similar regarding age, bone mineral density (BMD), follow-up period, severity of the deformity and fracture. Blood loss, operation time, and bed-rest time were less in the PKP group. VAS, ODI score improved more rapidly after surgery in the PKP group. No significant difference was found in VAS and ODI scores between the two groups at final follow-up (p > 0.05). Meanwhile, the height of anterior vertebrae (Ha), the height of posterior vertebrae (Hp) and the kyphosis angle showed significant improvement in each group (p < 0.05). The postoperative improvement in spinal canal compromise was not statistically significant in the PKP group (p > 0.05); there was a significant improvement in the SSPI group (p < 0.05). Moreover, these postoperative radiographic assessments showed significant differences between the two groups regarding the improvement of canal compromise (p < 0.05). At final follow-up, remodeling of spinal canal compromise was detected in both groups., Conclusion: Both PKP and SSPI appeared as effective and reliable operative techniques for selected amyelic thoracolumbar fractures in the short-term. PKP had a significantly smaller blood loss and shorter bed-rest time, but SSPI provided a better reduction. Long-time studies should be conducted to support these clinical outcomes.

In-line rainbow trapping is demonstrated in an optical microfiber with a plasmonic grating. The dispersions of x- and y-polarized surface plasmon polariton (SPP) modes are analyzed in detail by the 3D finite element method (FEM). In this system, the incident light is coupled from an optical microfiber into a graded grating. The plasmonic structure shows strong localization as the dispersion curve approaches cut-off frequency. Gradually increasing the depth or width of the grating elements ensures that the cut-off frequency of the SPP mode varies with the position along the microfiber. Near-infrared light at different frequencies can be trapped in different spatial positions. The in-line rainbow trapping is important for potential applications including optical storage, slow light, optical switch and enhanced light-matter interactions in fiber integrated devices and highly integrated optical circuits.

We propose, design and experimentally demonstrate highly-dispersive electromagnetically induced transparency (EIT) in planar symmetric metamaterials actively switched and controlled by angles of incidence. Full-wave simulation and measurement results show EIT phenomena, trapped-mode excitations and the associated local field enhancement of two symmetric metamaterials consisting of symmetrically split rings (SSR) and a fishscale (FS) metamaterial pattern, respectively, strongly depend on angles of incidence. The FS metamaterial shows much broader spectral splitting than the SSR metamaterial due to the surface current distribution variation.

We retrospectively studied patients who underwent posterior pedicle screw instrumentation for thoracolumbar fractures to explore the relationship between correction loss after the operation and clinical outcome. The study included 52 patients, with a minimum postoperative follow-up of 7 years (mean of 9.8 years). From the analysis of radiological and clinical outcomes, we found that the relevant factors related to functional outcome were: (i) preoperative anterior vertebral height (AVH; regression coefficient [B]=-0.075, p=0.045); and (ii) the latest follow-up AVH (B=-0.100, p=0.043). This indicates that function is likely to be worse if the anterior vertebral column is compressed more severely at the time of injury, and that function will also be worse if the AVH is decreased at the latest follow-up. However, loss of AVH was not correlated with functional outcome. Therefore, we recommend that the AVH should be restored as much as possible by posterior instrumentation during the treatment of thoracolumbar fractures. Reducing the loss of correction to maintain the postoperative AVH is also critical to maintain the AVH at latest follow-up., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

This article describes a retrospective study of patients who underwent posterior indirect reduction procedures for thoracolumbar burst fractures. The goal of this study was to explore a simple and effective method for evaluating the reduction of spinal canal fragments during posterior indirect reduction procedures.Sixty-four burst fractures with retropulsed bone fragments encroaching the spinal canal at the thoracolumbar junction were performed. C-arm fluoroscopy was used to evaluate the spinal canal fragments' reduction. A standard lateral view of the thoracolumbar spine was set up. When a continuous and smooth posterior vertebral body line of the injured vertebrae appeared, similar to below and above the vertebrae, the spinal canal bone fragment was considered to be satisfactorily reduced. The midsagittal diameter of the injured segment was measured on preoperative and postoperative computed tomography (CT) scans. Narrowing of the midsagittal diameter of the injured segment was improved from 41.4%+/-15.9% to 13.7%+/-9.7%. The correction value was 27.6%+/-15.6%. All pre- and postoperative outcome variables had statistical significance (P<.01). Forty-two patients experienced a restored posterior vertebral body line with a continuous and smooth vertical line, indicating that the fragment reduction was satisfactory. Post-operative CT showed that the spinal canal compromise was <10% (range, 0%-9.8%; mean, 6.1%+/-2.9%).Continuous and smooth posterior vertebral body line imaging is a simple and effective method to judge the reduction of a bone fragment retropulsed into the spinal canal. It can provide evidence as to whether a laminotomy and pushing the bone fragment are necessary during posterior surgery., (Copyright 2010, SLACK Incorporated.)