Z-domain modeling approach of a multilayer sextuple-coupled micro-ring resonator with 1 × 5 input-output bus waveguides as optical filters.

This paper introduces the modeling approach of a new micro-ring resonator configuration composite of six asymmetrical rings with one input and five output bus waveguides. This multilayer sextuple-coupled micro-ring resonator (MSCMRR) is modelled in the z domain by practicing the delay line signal approach and Mason's gain formula. Both lateral coupling and vertical coupling are used to design this MSCMRR structure to confine it up to four layers. Performance analysis is carried out in a MATLAB platform with the graphical representation of performance parameters like free spectral range (FSR), group delay, dispersion, full width at half-maximum, etc. The optical couplers of the proposed model are also designed by the finite-difference time-domain (FDTD) method. Electric field propagation through the rings and the waveguides are also studied by FDTD. The proposed structure offers different values of high FSR with zero crosstalk at every output port that ensures the quality application of this proposed model as an optical add-drop filter in an optical communication network.

Performance analysis of triple asymmetrical optical multiple ring resonator with a 1 × 3 input-output waveguide for application as an optical filter.

Modelling of a triple asymmetrical optical multiple ring resonator (TAOMRR) with a 1×3 input-output waveguide has been carried out in the present paper, and its performance as an optical filter is analyzed. The mathematical modelling of the proposed configuration is carried out in the z domain using a delay line signal processing technique. Free spectral range (FSR), group delay, and dispersion characteristics of the proposed TAOMRR are evaluated from the frequency response plot obtained in MATLAB from all the possible input-output port configurations. The field analysis of the proposed configuration is realized using the finite difference time domain (FDTD) method. The optimal coupling coefficient obtained from the MATLAB simulation is used to design the various optical couplers in FDTD analysis. The proposed configuration offers three outputs with different FSRs for a single input port, which greatly enhances the data handling capabilities in communication networks.

Modeling and performance analysis of vertically coupled triple microring resonator in the Z domain.

A theoretical model of vertically coupled triple microring resonators (VCTMRRs) in the Z domain is presented in this work. Delay line signal processing approach in Z-domain modeling is used for the performance analysis of waveguide-based VCTMRRs. Overall transmittance of the VCTMRR is determined in the Z domain, and frequency response is evaluated in a MATLAB environment. Performance in terms of free spectral range (FSR) and crosstalk of VCTMRR with two symmetric rings is compared with previously published results, and found to be in close agreement. VCTMRR architectures with different ring length combinations have been considered for the analysis. Performance of a VCTMRR with three asymmetric rings is also reported and compared with the performance of a VCTMRR with two symmetric rings in the present work. The design provides transmission characteristics where spurious transmission (crosstalk) at the interstitial frequencies that lie between the extended FSR is adequately suppressed. Group delay and dispersion characteristics are also presented.

Enhancement of free spectral range using pentuple microresonator.

The work addresses the issues of the ever-expanding demand of wide free spectral range (FSR) compatible integrated optic passive devices used in commercial communication systems like dense wavelength division multiplexing and a host of other applications. FSR expansion has been achieved by using the Vernier principle. The analysis has been carried out using Mason's rule and the delay line signal processing approach. Performances of two resonator structures made of silicon-on-insulator-based waveguides with two different effective refractive indices, viz., 1.7 and 2.811, have been compared. The maximum FSR of 3527 THz with finesse of 4409 has been obtained from the first architecture.

Rabeto plus: a valuable drug for managing functional dyspepsia.

The aim of the study was to evaluate and document the efficacy and tolerability of rabeto plus (FDC of rabeprazole and itopride) in management of functional dyspepsia. It was an open, prospective, non-comparative, multidose study. The patients with functional dyspepsia (NERD or non-erosive reflux disease) attending OPD of a leading, tertiary care, teaching hospital in West Bengal (BS Medical College, Bankura) were inducted in the study. A total of 46 adult patients of either sex with functional dyspepsia and a clinical diagnosis of NERD were given 1 capsule of rabeto plus before breakfast, for up to 4 weeks. Primary efficacy variables were relief from symptoms of heartburn, nausea, vomiting, waterbrash and fullness. Secondary efficacy variables were global assessment of efficacy and toleration by patients and treating physicians. The tolerability was assessed on the basis of record of spontaneously reported adverse events with their nature, intensity and outcome. Out of 55 patients enrolled in the study, 46 completed the study as planned, while 9 patients were lost to follow-up (dropped). Most patients reported near total symptom relief by the end of study. Total symptom score showed remarkable and significant improvement from baseline to end of the study. Importantly, none of the patients reported any side-effect. All participants tolerated the drug well. Moreover, response to study drug was rated as excellent or good by over 93% patients and their treating physicians. This means that 9 out 10 patients receiving rabeto plus reported desired symptom relief from dyspepsia. Thus it was concluded that rabeto plus is a valuable drug for treatment of functional dyspepsia or NERD.

Gallbladder cancer with duodenal infiltration: is it still resectable?

OBJECTIVE: To assess the resectability and the long-term survival in patients of gallbladder cancer with duodenal involvement. BACKGROUND: Duodenal infiltration in patients of carcinoma gallbladder is generally regarded as a sign of advanced disease and an indicator of unresectable disease. METHODS: A total of 252 patients of gallbladder cancer (GBC) who underwent surgery over a 5-year period were studied for duodenal involvement. Patients with duodenal infiltration on per-operative assessment were analyzed for resectability, postoperative morbidity, mortality and disease free survival. RESULTS: Forty-three patients were detected to have duodenal infiltration on per-operative assessment out of which 17 had unresectable disease (39.54%), whereas the remaining 26 patients underwent R0 resection (61.9%). Of these, nine underwent distal gastrectomy with resection of the first part of the duodenum (34.62%), 16 underwent duodenal sleeve resection (61.54%), and in one patient pancreatoduodenectomy (HPD) (3.85%) was performed. With regard to the extent of liver resection, two underwent extended right hepatectomy, whereas the remaining 24 underwent segment IVB and V resection. Bile duct and adjacent viscera were resected when involved. Of the resected patients, eight underwent bile duct excision, seven had colonic resection, and three had vascular resection and reconstruction. The postoperative morbidity and mortality was 15 (34.9%) and three (6.97%), respectively, in the resected group of patients. The overall actual survival in the resected group was a mean of 15.87 months, median of 14 months (range 3 to 56 months). CONCLUSION: Duodenal infiltration is neither an indicator of unresectability nor an indication to perform Hepato-pancreatoduodenectomy (HPD). In most of these patients, an oncologically adequate R0 resection can be performed with either a duodenal sleeve resection or distal gastrectomy with resection of the first part of the duodenum.

Biliary obstruction in gall bladder cancer is not sine qua non of inoperability.

BACKGROUND: The presence of biliary obstruction in patients with gallbladder cancer (GBC) is generally viewed as an indicator of advanced disease, inoperability and poor prognosis. METHODS: Data was collected from patients with GBC with obstructive jaundice who underwent resection during the period January 2001 to October 2003. Systematic analysis of prospective data was undertaken; patients were analyzed for resectability, post-operative morbidity, mortality and disease-free survival. RESULTS: During this period 14 patients with GBC with biliary obstruction underwent resection with curative intent. In these jaundiced patients, the resectability rate was 27.45% (14 of 51). In the jaundiced group the mortality was 7.14% the morbidity rate 50%, the mean disease free survival was 23.46 months (median 26 months and range of 2 to 62 months). Seven patients (50%) survived more than two years. CONCLUSION: Biliary obstruction in gall bladder cancer is not sine qua non of inoperability and resection results in meaningful prolongation of survival.

Modeling and analysis of an extrinsic Fabry-Perot interferometer cavity.

A schematic representation of optical feedback between two resonator mirrors undergoing a phase shift each round trip as a function of the separation of the mirrors is studied. A transfer function modeling of the extrinsic Fabry-Perot interferometer (EFPI) is presented. Nyquist analysis has been used to forecast the operational stability and possibility of interference in an EFPI. The analysis with two perfectly parallel surfaces of the cavity shows efficient interference. The performance when there is some tilt between the two mirrors in the cavity is also studied and is presented. In this case some restricted interference is found.

Unusual complication of internal jugular vein cannulation.

Internal jugular cannulation is a common procedure in the hospitals. We report a rare complication where the guide wire was pushed into the internal jugular vein without threading the catheter through. Complications due to central venous cannulation are also discussed.