No abstract

No abstract

Background: Learning curve of laparoscopic nephrectomy (LN) is mainly affected by two main factors: plotting performance and experience. However, there is paucity in the literature addressing the number of cases required to adopt LN. Herein, we aimed to assess the learning curve of LN for various renal disorders and number of cases required to adopt the technique. Between September 2015 and December 2017, consecutive patients undergoing LN for various renal diseases were enrolled in this study. Patients were divided into two groups, the first 20 cases (group A) and subsequent 20 cases (group B). All procedures were performed by a single trainee urologist under supervision of an expert endourologist. Learning curve was assessed using operative time and incidence of complications. Results: A total of 40 patients were included in this pilot clinical study. Mean age was 38.2 ± 16.3 years. The mean operative time for patients in group B was significantly lower than the mean operative time for patients in group A (108.5 vs. 139.3 min, p < 0.05). However, there were no significant differences between both groups in terms of intraoperative blood loss (86 vs. 104 ml; p = 0.081), conversion to open surgery (5% vs. 10%; p = 0.256) and postoperative complications (5% vs. 15%; p = 0.09) for group B and group A, respectively. Similarly, there was no significant difference between both groups in terms of hospital stay (42 ± 8 vs. 46 ± 11 h p = 0.01). The trainee surgeon reached a plateau after 22 cases. Conclusions: Our study suggests that a minimum of 22 LN procedures are needed in order to adopt the technique of laparoscopic nephrectomy. Learning curve of LN is mainly affected by number of performed procedures within a short period of time.

A DC glow discharge operating with a virtual cathode is studied. The system consists of a solid disc cathode and mesh anode. The discharge occurs in nitrogen gas at the left-hand side of Paschen’s curve. The plasma electron density in the axial direction has been found to be 0.2 · 108 cm−3 at 2 cm from the mesh. The electron temperature peak value has been found to be 3.5 eV at 6 cm from the mesh. The radial distribution of the plasma electron density and temperature are discussed. The variation of the plasma parameters are in good agreement with the experimental results.

High-speed shock-wave propagation in a cylindrical tube at low initial gas pressure has been investigated. A shock-wave was excited by fast magnetic compression of a plasma in a conical θ-pinch-type electrodeless device. The Mach number varied from 10 to 100, and the initial pressure from 20 μm Hg to 250 μm Hg. At high initial pressures the shock-wave properties were identical to those of a ‘snow-plough’ model. At low pressures an anomalous wave attenuation was observed which could not be explained by the existing theory. The shock-front width is in good agreement with that predicted by the ion-ion collision theory.