A computationally efficient methodology based on computational fluid dynamics (CFD) has been developed to predict the flow field and infrared signatures of rocket motor plumes. Because of the extreme environment in the plume and the difficulties in taking measurements of motors in flight, it has been partially validated with temporally- and spatially resolved imaging spectrometer data from the static firings of small flight-weight motors using a non-aluminized composite propellant. Axisymmetric simulations were carried out for a variety of motor burn time, flight velocity, altitude, and modeling parameters to establish their effects on the results. By extrapolating the axisymmetric CFD output into three dimensions, images of the rocket plume as seen by an infrared sensor outside the computational domain were also created. The CFD methodology correctly predicted the afterburning zone downstream of the nozzle, and good agreement for its location was obtained with the imaging spectrometer data. It also showed that flight velocity and altitude have substantial effects on the size, shape, and infrared emissions of the plume. Smaller effects on plume properties were predicted for different motor burn times, but indicated that more experimental data of greater temporal and spatial resolution of single static firings are required to better validate the CFD plume prediction methodology.

Introduction and Objective: Symptomatic calyceal diverticula, particularly those containing stones, are simple anatomic problems that often require complex surgical solutions. Calyceal diverticula can present with intractable pain, hematuria, and recurrent infections. Techniques ranging from extracorporeal shockwave lithotripsy to open extirpative surgery have been applied to treat diverticula with varying success, although percutaneous approaches have become the primary minimally invasive therapy. However, anteriorly oriented diverticula or those that have failed percutaneous or ureteroscopic therapy present a management dilemma. Many of these complex patients are averse to another attempt at traditional management and are seeking a more definitive alternative. We present our series of four symptomatic women with complex calyceal diverticula who were managed using a novel robot-assisted laparoscopic diverticulectomy (RALD) technique. Materials and Methods: To illustrate the technique, we have selected a 22-year-old woman with a large, chronically symptomatic right upper pole posterior calyceal diverticulum. She had previously failed both ureteroscopic and percutaneous management despite being rendered stone free. She continued to have intractable pain and a large diverticular cavity remained present despite percutaneous management. Unwilling to undergo a second percutaneous approach, this patient was seeking a more definitive surgical option. The RALD technique is a modification of robot-assisted laparoscopic partial nephrectomy (RALPN) in which the diverticulum is identified by laparoscopic ultrasound and unroofed, stones are removed and the mucosa is resected in its entirety from the inside under vascular control. The ostium into the collecting system is ligated and the defect is closed hemostatically. This approach eliminates the need to resect a significant volume of normal renal parenchyma despite the endophytic nature of the diverticula. Results: The mean age (32 years), diverticula diameter (2.4 cm), operating time (212 minutes), blood loss (180 mL), warm ischemia time (26 minutes), length of stay (2.8 days) and duration of follow-up (7 months) were noted. Warm ischemia times were 17, 18, 28, and 39 minutes, reflecting a broad range of technical complexity. One patient had failed previous ureteroscopic management and two had failed both ureteroscopic and percutaneous approaches. The final patient had an anteriorly oriented lower pole calyceal diverticula not easily amenable to a percutaneous approach. No major complications occurred and there was no diverticula recurrence on imaging at 6 months. All patients were symptom free at their last clinic visit. Specific technical points from our full case experience are illustrated in detail in the accompanying video presentation. Conclusions: In our early experience, RALD appears to be effective for addressing complex symptomatic calyceal diverticula, particularly anteriorly oriented diverticula, those containing large calculi or those that have failed percutaneous and/or ureteroscopic management. Morbidity appears favorable as compared with percutaneous diverticulectomy. For surgeons facile with RALPN, the learning curve for RALD is relatively short. RALD is comparable in difficulty to robotic resection of a completely endophytic renal tumor with the caveat that finding the plane between the diverticular lining and parenchyma may be more challenging after failed percutaneous diverticular ablation. Warm ischemia times, therefore, may be slightly longer in the setting of RALD as compared with RALPN. No competing financial interests exist. Runtime of video: 7 mins 59 secs

PURPOSE:Managing the encrusted and retained ureteral stent is a potentially complex challenge. To improve surgical planning, we hypothesized that proximal stone burden is the most important factor associated with complicated removal, and that computerized tomography more accurately estimates stone burden than plain film x-ray of the kidneys, ureters and bladder.MATERIALS AND METHODS:Records were reviewed of patients undergoing surgical removal of an encrusted and retained ureteral stent or nephrostomy at Ben Taub General Hospital from 2007 to 2009. Preoperative imaging consisted of a plain x-ray of the kidneys, ureters and bladder and/or computerized tomography of the abdomen/pelvis. Each encrusted tube was assessed using the FECal (forgotten, encrusted, calcified) grading system and associated stone burden was calculated. Univariate and multivariate analyses were performed to determine factors associated with the need for multiple surgeries.RESULTS:A total of 55 encrusted and retained ureteral stents and 1 nephrostomy were removed from 52 patients. Mean tube duration was 24.9 months. Most tubes were removed endoscopically (94.2%). Of the patients 21.2% required multiple surgical procedures to remove each tube. Computerized tomography graded stone burden more accurately than plain x-ray of the kidneys, ureters and bladder (94.9% vs 64.4%, p = 0.01). Plain x-ray of the kidneys, ureters and bladder underestimated proximal stone burden in 44.4% of patients who underwent multiple surgeries. When dividing stone burden into 3 categories (0 to 100, 101 to 400 and greater than 401 mm(2)) only proximal stone burden correlated with multiple surgeries and surgical complications (p = 0.01 for both). On multivariate analysis only proximal stone burden was associated with multiple surgeries to remove each tube (OR 12.1, 95% CI 1.5-95.9, p = 0.02 for 101 to 400 mm(2) and OR 18.1, 95% CI 1.7-192.8, p = 0.02 for greater than 401 mm(2)).CONCLUSIONS:In patients with encrusted and retained ureteral stents accurate determination of the proximal stone burden, preferably by computerized tomography, is important for surgical counseling and planning.

Wide variations exist in the methods for evaluating potency following radical prostatectomy. We describe our technique of laparoscopic radical prostatectomy (LRP), present our methods for assessing the return of potency following LRP, and discuss the relevant literature. Sexual function was assessed pre- and postoperatively using the Expanded Prostate Cancer Index Composite questionnaire (EPIC). Sexual function subscale scores (SFSS) were reported as a percentage of preoperative baseline sexual function. The EPIC was also used for single-question assessment of successful intercourse. We also reviewed the literature on prospective health-related quality of life results following LRP and open radical retropubic prostatectomy. Only patients reporting preoperative intercourse were analyzed. Of these, 72 and 35% undergoing bilateral and unilateral nerve sparing (NS) reported postoperative intercourse at 12 months (P=0.01). Mean SFSS at 12 months was 61 and 57% of baseline after bilateral and unilateral NS, respectively (P=0.71). Following NS procedures, 74% of patients ⩽58 years of age and 41% of patients >58 years of age reported successful intercourse at 12 months (P=0.015). Mean SFSS was 64 and 52% of baseline function (P=0.249) at 12 months for patients ⩽58 and >58 years of age, respectively. In patients <58 years of age who underwent bilateral NS surgery, 82% reported intercourse at 12 months. In conclusion, return of sexual function following NS LRP in our experience is comparable to reports from centers of excellence in open prostatectomy. Standardizing data collection using validated quality of life instruments can provide both surgeon and patient with a realistic forecast of relative return to normal sexual function following prostatectomy.

Detonation propagation in a condensed explosive with compressible metal particles can result in significant momentum transfer between the explosive and the particles during the shock-particle interaction. Consequently, the classic assumption of a "non-momentum-transfer shock" used in multiphase continuum detonation initiation and propagation models may not be valid. This paper addresses this issue by performing numerical and theoretical calculations in liquid explosives and RDX with various compressible metal particles under conditions of detonation pressure. The results showed that immediately behind the shock front the velocity of particles such as Al and Mg can achieve 60 94% the value of the shocked velocity of the explosive.

Laparoscopic radical retropubic prostatectomy (LRRP) is a new technique for treating organ-confined prostate carcinoma. The procedure was first described and proven to be feasible in 1997. To date, the results from over 150 cases have been reported in the literature. LRRP appears to be an efficacious procedure and deserves careful consideration. However, open radical retropubic prostatectomy (RRP) is routinely performed with excellent results and minimal morbidity. Whether LRRP offers any compelling benefit over open RRP remains to be determined, and will require a systematic comparison of technical advantages, morbidity, and long-term functional outcomes.

Locus coeruleus (LC) noradrenaline (NA) neurons innervate forebrain structures, such as hippocampus, thalamus and cortex, that are important for the regulation of cognitive processes (Foote, 1987). Dysfunction of LC NA cells has been associated with the cognitive decline observed in Parkinson’s disease (PD) and in some patients with Alzheimer disease (AD). Indeed, the number of LC cells may be severely depleted in the brains of AD and PD patients.

Investigation of the inner ear is still the subject of basic research. The concept of an active filtering process in the mechano-electrical transfer mechanism in the inner ear (cochlea) was introduced. In this paper an optical approach detecting microvibrations is discussed. A fiber optic heterodyne interferometer with a miniaturized sensorhead was built. The fibers ensure flexibility and easy handling of the interferometer whereas the miniaturized sensorhead allows a non-invasive approach to the organ of Corti. In heterodyne interferometry as compared to classical interferometry two slightly different light frequencies for the reference and object beams are used. The vibration of the object is detected as a modulation of the phase of the detector signal. To obtain the information on the vibration two methods were analyzed and applied: namely measuring the amplitude of the sidebands in the spectrum of the modulated signal and secondly signal demodulation. It is possible to detect amplitudes down to 0.3 angstrom in a frequency range of 500 Hz to 50 kHz with a simulated object reflectivity of 0.02%.

Investigation of the inner ear is still subject of basic research. Due to the small structures of the inner ear every suggested measurement technique, which includes loading of moving parts, will not be able to detect the oscillations correctly. Therefore an optical approach detecting microvibrations in the cochlea will be discussed. In heterodyne interferometry as compared to classical interferometry two slightly different light frequencies for the reference and object beams are used. The vibration of the object is detected as a modulation of the phase of the detector signal. Many restrictions on the design of our new interferometer caused by the properties of the tissue of the membranes in the cochlea and by the anatomic and geometric shape of the surrounding of the cochlea, needed to be taken into account. A confocal fiber optic heterodyne interferometer with a miniaturized sensor head was built. To improve the optical properties of the sensor head the combination of a gradient index lens and a hologram is under test. The selected wavelength of 830 nm should allow an investigation of layered tissues. It is possible to detect amplitudes down to 0.3 angstroms in a frequency range of 500 Hz to 50 kHz with a simulated object reflectivity of 0.02%.