Point Mean Beam Length, a New Concept to Enhance the Computational Efficiency of Multi-Dimensional, Non-Gray Radiative Heat Transfer.

A new concept of point mean beam length (PMBL) is introduced. For enclosures with simple geometry, this concept provides a fundamental self-consistent interpretation on the various different definition of the conventional mean beam length. The concept is further demonstrated to be effective in enhancing the computational efficiency for multi-dimensional radiative heat transfer in non-gray media. In the evaluation of radiative exchange between two perpendicular areas with a common edge, the use of PMBL leads to a factor of 100 to 400 reduction in computational effort compared to the direct integration approach. For practical applications, PMBL is combined with RADNNET (a neural network correlation for a one-dimensional CO2/H2O/soot combustion mixture) to generate two highly efficient and accurate solvers for the evaluation of exchange factors between two parallel or perpendicular rectangular areas of arbitrary dimensions with an intervening combustion mixture.

Heat Transfer in a Falling Laminar Liquid Film with In-Depth Radiation Absorption.

A heat transfer problem involving a steady-state falling liquid film along a vertical wall with an imposed constant heat flux on the liquid film surface and an in-depth thermal radiation absorption in the film layer is analyzed. The liquid film is assumed to be normal to the incident radiative heat flux, and the heat flux is assumed to be parallel and unidirectional. Nondimensionalized governing equations are formulated and solved numerically. Sample calculations are provided. The effects of pertinent dimensionless parameters on the heat transfer process are demonstrated. The calculated results reveal that the in-depth thermal radiation absorption would play a key role in the heat transfer in the liquid film.

Development and evaluation of a positive youth development course for university students in Hong Kong.

With higher education, university graduates are important elements of the labor force in knowledge-based economies. With reference to the mental health and developmental problems in university students, there is a need to review university's role in nurturing holistic development of students. Based on the positive youth development approach, it is argued that promoting intrapersonal competencies is an important strategy to facilitate holistic development of young people in Hong Kong. In The Hong Kong Polytechnic University, a course entitled Tomorrow's Leader focusing on positive youth development constructs to promote student well-being will be offered on a compulsory basis starting from 2012/13 academic year under the new undergraduate curriculum structure. The proposed course was piloted in 2010/11 school year. Different evaluation strategies, including objective outcome evaluation, subjective outcome evaluation, process evaluation, and qualitative evaluation, are being carried out to evaluate the developed course. Preliminary evaluation findings based on the piloting experience in 2010/11 academic year are presented in this paper.

Patients with end-stage renal disease are candidates for robot-assisted laparoscopic radical prostatectomy.

BACKGROUND AND PURPOSE: Patients with end-stage renal disease (ESRD) have multiple comorbidities that place them at increased risk for surgical complications. Consequently, patients with both ESRD and prostate cancer (PCa) have rarely been considered candidates for radical prostatectomy. The objective of this study is to compare ESRD patients who are undergoing robot-assisted laparoscopic prostatectomy (RALP) with a cohort of patients with no history of dialysis. PATIENTS AND METHODS: A retrospective review was conducted of 430 patients who were undergoing RALP, including 12 receiving dialysis at the time of surgery. Preoperative demographics, perioperative parameters, and postoperative outcomes were compared using a two-tailed Student t test and a chi-square test, with significance at P<0.05. RESULTS: Patient demographics including body mass index, Gleason score, and prostate-specific antigen (PSA) value were similar between the two groups. Patients with ESRD had younger age (55.5 vs 62.9 years; P<0.01), higher American Society of Anesthesiologists scores (3.7 vs 2.5; P<0.01), and higher age-adjusted Charlson Comorbidity Index scores (6.2 vs 4.2; P<0.01). Patient outcomes including operative time, estimated blood loss, complication rate, postoperative stay, and positive margins did not differ significantly between groups. No ESRD patients needed pads or had a detectable PSA level using an ultrasensitive assay. CONCLUSIONS: This series represents the largest series of patients with ESRD undergoing RALP. These patients experienced similar outcomes compared with patients with no history of dialysis despite greater preoperative comorbidity. RALP produces minimal fluid shifts, low blood loss, and excellent cancer control, making it an ideal treatment option to prepare patients with both ESRD and PCa for renal transplantation.

Hybrid transureteral natural orifice translumenal endoscopic nephrectomy: a feasibility study in the porcine model.

BACKGROUND AND PURPOSE: Natural orifice approaches for nephrectomy have included access via the stomach, vagina, bladder, and rectum. The use of the ureter as a natural orifice for natural orifice translumenal endoscopic surgery (NOTES) nephrectomy has not been previously reported. The purpose of this study is to test the feasibility of transureteral laparoscopic NOTES nephrectomy. MATERIALS AND METHODS: Three female farm pigs (29.2-30.8 kg) were placed into the lithotomy position. A cystoscopically placed extra-stiff guidewire was used to place a prototype dilating sheath into the left ureter. After dilation of the ureter and urethra, the sheath was exchanged for a 12-mm bariatric laparoscopic trocar. A 10.5-inch long 10-mm offset operating laparoscope with an internal 5-mm working port was used for the nephrectomy. One 2-mm and one 2/3-mm port were placed transabdominally to facilitate in situ morcellation. The kidney was cut into slices using the bipolar device and extracted via the ureteral port using the housing of a 12-mm bariatric stapling device. RESULTS: All three transureteral nephrectomies were successfully completed. The total mean operative time was 220 minutes (range 113-346 min). Component portions of the procedure were: Ureteral access (mean 21 min), nephrectomy (mean 70 min), and kidney morcellation (mean 103 min). Mean estimated blood loss was 20 mL (range 5-50 mL). There were no intraoperative complications. CONCLUSIONS: This nonsurvival porcine feasibility study demonstrates the successful performance of transureteral nephrectomy. This approach shows promise as a way to decrease the invasiveness of NOTES nephrectomy by using the ureteral orifice as an access site.