We report a simple technique in microwave photonic (MWP) signal processing that allows the use of an optical filter with a shallow notch to exhibit a microwave notch filter with anomalously high rejection level. We implement this technique using a low-loss, tunable Si 3 N 4 optical ring resonator as the optical filter, and achieved an MWP notch filter with an ultra-high peak rejection > 60 dB, a tunable high resolution bandwidth of 247-840 MHz, and notch frequency tuning of 2-8 GHz. To our knowledge, this is a record combined peak rejection and resolution for an integrated MWP filter.

We propose and experimentally demonstrate new architectures to realize multi-tap microwave photonic filters, based on the generation of a single or multiple dynamic Brillouin gratings in polarization maintaining fibers. The spectral range and selectivity of the proposed periodic filters is extensively tunable, simply by reconfiguring the positions and the number of dynamic gratings along the fiber respectively. In this paper, we present a complete analysis of three different configurations comprising a microwave photonic filter implementation: a simple notch-type Mach-Zehnder approach with a single movable dynamic grating, a multi-tap performance based on multiple dynamic gratings and finally a stationary grating configuration based on the phase modulation of two counter-propagating optical waves by a common pseudo-random bit sequence (PRBS).

Silicon nitride photonics is on the rise owing to the broadband nature of the material, allowing applications of biophotonics, tele/datacom, optical signal processing and sensing, from visible, through near to mid-infrared wavelengths. In this paper, a review of the state of the art of silicon nitride strip waveguide platforms is provided, alongside the experimental results on the development of a versatile 300 nm guiding film height silicon nitride platform.

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AIM:To study the morbidity and complications associated to ileostomy reversal in colorectal surgery patients, and if these are related to the time of closure. METHODS:A retrospective analysis of 93 patients, who had undergone elective ileostomy closure between 2009 and 2013 was performed. Demographic, clinical and surgical variables were reviewed for analysis. All complications were recorded, and classified according to the Clavien-Dindo Classification. Statistical univariate and multivariate analysis was performed, setting a P value of 0.05 for significance. RESULTS:The patients had a mean age of 60.3 years, 58% male. The main procedure for ileostomy creation was rectal cancer (56%), and 37% had received preoperative chemo-radiotherapy. The average delay from creation to closure of the ileostomy was 10.3 mo. Postoperative complications occurred in 40% of the patients, with 1% mortality. The most frequent were ileus (13%) and wound infection (13%). Pseudomembranous colitis appeared in 4%. Increased postoperative complications were associated with delay in ileostomy closure (P = 0.041). Male patients had more complications (P = 0.042), mainly wound infections (P = 0.007). Pseudomembranous colitis was also associated with the delay in ileostomy closure (P = 0.003). End-to-end intestinal anastomosis without resection was significantly associated with postoperative ileus (P = 0.037). CONCLUSION:Although closure of a protective ileostomy is a fairly common surgical procedure, it has a high rate of complications, and this must be taken into account when the indication is made. The delay in stoma closure can increase the rate of complications in general, and specifically wound infections and colitis.© 2014 Baishideng Publishing Group Inc. All rights reserved.Key words: Protective ileostomy; Stomas; Stoma-related complications; Surgical infections; Colorectal surgery Core tip: Protective ileostomies are widely used by surgeons for the protection of anastomoses, but they imply a second intervention for reversal. Despite being considered a minor intervention, ileostomy reversal does not lack complications. Adjuvant treatment, complications from the first intervention, or low-priority consideration can delay the closure of the stoma. In our study, we reviewed all complications following ileostomy reversal and found they were considerably high (40%), and increased as did the time (in months) until closure (P = 0.041). In multivariate analysis, male patients had more complications (P = 0.042), mainly wound infections (P = 0.007). Pseudomembranous colitis was also associated with the delay in ileostomy closure (P = 0.003).Rubio-Perez I, Leon M, Pastor D, Diaz Dominguez J, Cantero R. Increased postoperative complications after protective ileostomy closure delay: An institutional study. World J Gastrointest Surg 2014; 6(9): 169-174 Available from:

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