RESUMEN
We demonstrate a technique for SBS reduction in a nanosecond Yb-fiber amplifier by imposing 1.19 GHz/ns frequency chirp on the seed pulses with a pulse-driven phase modulator. A nearly 9-fold increase in the SBS threshold was observed for 8.4 ns pulses. SBS threshold data and transient SBS gain for various degrees of chirp are reported and compared with theoretical calculations. We further demonstrate the recovery of the input narrowband spectrum by applying an opposite chirp with a second phase modulator after the amplification.
RESUMEN
BACKGROUND: Many of thoracic minimally invasive interventions have been proven to be possible without general anesthesia. This article presents results of video-assisted thoracic surgery (VATS) application under local anesthesia in patients with lung abscesses and discusses its indications in detail. METHODS: The study involved prospective analysis of treatment outcomes for all acute infectious pulmonary destruction (AIPD) patients undergoing VATS under local anesthesia and sedation since January 1, 2010, till December 31, 2013. Patients with pulmonary destruction cavity at periphery of large size (>5 cm) underwent non-intubated video abscessoscopy (NIVAS). Patients with pyopneumothorax (lung abscess penetration into pleural cavity) underwent non-intubated video thoracoscopy (NIVTS). Indications for NIVAS and NIVTS were as follows: cavity debridement and washing, necrotic sequestra removal, adhesion split, biopsy. All interventions were done under local anesthesia and sedation without trachea intubation and epidural anesthesia. RESULTS: Sixty-five enrolled patients had 42 NIVAS and 32 NIVTS interventions, nine patients underwent two surgeries. None of the patients required trachea intubation or epidural anesthesia. In none of our cases with conversion to thoracotomy was required. Post-surgical complications developed after 11 interventions (13%): subcutaneous emphysema (five cases), chest wall phlegmon (three cases), pulmonary bleeding (two cases), and pneumothorax (one case). One patient died due to the main disease progression. In 50 patients NIVAS and NIVTS were done within 5 to 8 days after abscess/pleural cavity draining, while in other 15 patients-immediately prior to draining; both pulmonary bleeding episodes and all cases of chest wall phlegmon took place in the latter group. CONCLUSIONS: NIVAS and NIVTS under local anesthesia and sedation are well tolerated by patients, safe and should be used more often in AIPD cases. Timing of NIVAS and NIVTS procedures was found to be of paramount importance for ensuring complete therapeutic effectiveness.
RESUMEN
In many remote sensing applications one or multiple Fabry-Perot etalons are used as high-spectral-resolution filter elements. These etalons are often coupled to a receiving telescope with a multimode fiber, leading to subtle effects of the fiber mode order on the overall spectral response of the system. A theoretical model is developed to treat the spectral response of the combined system: fiber, collimator, and etalon. The method is based on a closed-form expression of the diffracted mode in terms of a Hankel transform. In this representation, it is shown how the spectral effect of the fiber and collimator can be separated from the details of the etalon and can be viewed as a mode-dependent spectral broadening and shift.
