Direct ultrafast laser written C-band waveguide amplifier in Er-doped chalcogenide glass

This paper reports the fabrication and characterization of an ultrafast laser written Er-doped chalcogenide glass buried waveguide amplifier; Er-doped GeGaS glass has been synthesized by the vacuum sealed melt quenching technique. Waveguides have been fabricated inside the 4 mm long sample by direct ultrafast laser writing. The total passive fiber-to-fiber insertion loss is 2.58 +/- 0.02 dB at 1600 nm, including a propagation loss of 1.6 +/- 0.3 dB. Active characterization shows a relative gain of 2.524 +/- 0.002 dB/cm and 1.359 +/- 0.005 dB/cm at 1541 nm and 1550 nm respectively, for a pump power of 500 mW at a wavelength of 980 nm. (C) 2012 Optical Society of Americ

Nanoindentation studies on waveguides inscribed in chalcogenide glasses using ultrafast laser

Optical straight waveguides are inscribed in GeGaS and GeGaSSb glasses using a high repetition-rate sub-picosecond laser. The mechanical properties of the glasses in the inscribed regions, which have undergone photo induced changes, have been evaluated by using the nanoindentation technique. Results show that the hardness and elastic modulus of the photo-modified glasses are significantly lower as compared to the other locations in the waveguide, which tend to be similar to those of the unexposed areas. The observed mechanical effects are found to correlate well with the optical properties of the waveguides. Further, based on the results, the minimum threshold values of hardness and elastic modulus for the particular propagation mode of the waveguide (single or multi), has been established

Comprehensive Analysis of Complications and Outcome of Laparoscopic Cholecystectomy in K.A.P.V. Government Medical College & Hospital

INTRODUCTION: Gall stone disease is common in India, that too affecting mostly middle age group men and women. The classical open cholecystectomy and the minimally invasive laparoscopic cholecystectomy are two alternative operations for removal of the gallbladder in recent era. In my study I choose this topic as we post graduates and young surgeons of Government K.A.P.V Medical College who are in laparoscopic learning curve, under the guidance of professors and associate professors doing laparoscopic cholecystectomy and proposed for a comprehensive analysis of complications and outcome of Laparoscopic cholecystectomy and comparing the results with existing study. AIM OF THE STUDY: Our aim of the study is to analyse the complications and outcome of laparoscopic cholecystectomy in our teaching institution. Parameters discussed here are : 1. Technique of surgery, 2. Duration of surgery, 3. Complications of surgery, 4. Post-operative morbidity, 5. Analgesic and antibiotic requirements, 6.Hospital stay& 7. Return to work. METHODOLOGY: My study is a prospective randomized study included 60 patients with gallstones, who were admitted to K.A.P.V Medical College & Hospital within the period of 15 months. The selection of procedure was decided depending up on the inclusion and exclusion criteria, exception when patient consent was not given for a particular procedure. The study was approved by Ethical Committee. Duration of study: One year. Study design : Prospective study. Sample Size: 60 cases. Inclusion Criteria: Age between 25 to 70 years. USG confirmation of GB calculus without obstructive features. Cholelithiasis without choledocholithiasis or complications. Cholelithiasis without anomalous biliary tract. Exclusion Criteria: Age 70 years. Features of obstructive jaundice. Patient presenting with cholelithiasis and choledocholithiasis. Patient presenting with gallbladder Malignancy. Patient presenting with anomalous biliary tract. After proper pre-operative workup following the proposed guidelines, patients were studied with reference to duration of surgery, post-operative analgesia, post-operative stay and morbidity, intra operative and post-operative complications. CONCLUSION: As per the study data the laparoscopic cholecystectomy has advantages regarding duration of hospital stay and convalescence. Benefits of laparoscopic approach include reduced hospitalization, decreased pain, avoidance of large incision with improved cosmetic purpose and reduced post-operative recovery time with an early return to work

How are Forbush decreases related to interplanetary magnetic field enhancements ?

Aims. Forbush decrease (FD) is a transient decrease followed by a gradual recovery in the observed galactic cosmic ray intensity. We seek to understand the relationship between the FDs and near-Earth interplanetary magnetic field (IMF) enhancements associated with solar coronal mass ejections (CMEs). Methods. We use muon data at cutoff rigidities ranging from 14 to 24 GV from the GRAPES-3 tracking muon telescope to identify FD events. We select those FD events that have a reasonably clean profile, and magnitude > 0.25%. We use IMF data from ACE/WIND spacecrafts. We look for correlations between the FD profile and that of the one hour averaged IMF. We ask if the diffusion of high energy protons into the large scale magnetic field is the cause of the lag observed between the FD and the IMF. Results. The enhancement of the IMF associated with FDs occurs mainly in the shock-sheath region, and the turbulence level in the magnetic field is also enhanced in this region. The observed FD profiles look remarkably similar to the IMF enhancement profiles. The FDs typically lag the IMF enhancement by a few hours. The lag corresponds to the time taken by high energy protons to diffuse into the magnetic field enhancement via cross-field diffusion. Conclusions. Our findings show that high rigidity FDs associated with CMEs are caused primarily by the cumulative diffusion of protons across the magnetic field enhancement in the turbulent sheath region between the shock and the CME.Comment: accepted in A&

Road accident cost prediction model using systems dynamics approach

Accident costs are an important component of external costs of traffic, a substantial part is related to fatal accidents. The evaluation of fatal accident costs crucially depends on the availability of an estimate for the economic value of a statistical life. This paper aims to develop a model for road accident through systems dynamics approach. To build an accident model, various factors causing the road accident and cost were identified. This model is capable of calculating the accident rate and its costs for the future. In this study the accident caused by bus alone is considered. The cost model is dealt more in this study as it requires more complex assessment. The accident model is built on the year 2000 data and predicted the accidents up to 2020 for every 5‐year interval. The accident model is valuated by comparing the predicted and actual accident data for the year 2005. Three scenarios were studied by changing the income growth rate and discount rate. Finally, best scenario is suggested for implementation. The outcome of the study is highly useful for the planners, administrators and police to make their decisions effectively for road safety investment projects. First published online: 27 Oct 201