Temperature and intensity dependence of Yb-fiber laser light absorption in water.

Absorption of CW Yb-fiber laser light of 1.07 µm wavelength in water has been measured at different water temperatures and laser intensities. The absorption coefficient was estimated to be 0.135 cm(-1) at 25 °C water temperature, and this was found to decrease with temperature at a rate of 5.7 × 10(-4) cm(-1) °C(-1). The absorption coefficient increased significantly when the laser beam was focused in water, and the increase depended on the distance of the focal point from the water surface. This has been attributed to the absorption and scattering losses of laser radiation in a cavity formed in water by the focused beam at laser intensities in the megawatts per square centimeter and higher range.

Laparoscopic sleeve gastrectomy: our first 100 patients.

BACKGROUND: Laparoscopic sleeve gastrectomy is becoming a popular procedure for the morbidly obese patient. Its utilization as a standalone procedure has good results with weight loss in short- and midterm reports. The aim of this study was to assess our technique and whether it warranted any modifications in the early postoperative period. METHODS: Our first 100 consecutive patients undergoing laparoscopic sleeve gastrectomy were retrospectively reviewed. Data analysis was conducted at 3 and 6 months to assess the percentage of excess body weight loss and comorbidity status change. RESULTS: The percentage of excess body weight loss at the 3- and 6-month marks was 34.2% and 49.1%, respectively. Comorbidities were also improved at the 3- and 6-month marks. Hypertension resolved in 38%, hyperlipidemia resolved in 19%, and diabetes in 46%. Complication rate during the first 6 months was 10%. Major complications included 2 patients with postoperative bleeding, 2 patients with acute renal failure from dehydration, and 1 postoperative bleeding patient who developed a gastric fistula. No surgical reintervention was required for any complication. CONCLUSION: Our technique is a safe method that is easily reproducible and does not require any modification. Laparoscopic sleeve gastrectomy is an excellent surgical option with a low complication rate.

Analysis of tuning of Bragg wavelength of photowritten fiber Bragg gratings during the inscription process using a biprism.

This paper presents an analysis of a simple biprism-based technique that enables inscription of multiple fiber Bragg gratings (FBGs), each with different Bragg wavelength, into a section of an optical fiber. The method offers a tuning range for Bragg wavelength that is comparable to that of the multiple mirror interferometer method. This has an additional advantage over multiple mirror interferometer methods, in that it does not require shifting of the fiber position perpendicular to the fiber axis, over a wide tuning range. Results of an analysis on how such tuning of Bragg wavelengths affects other important parameters of FBGs such as length, bandwidth, and reflectivity have been presented.