An alternative pressure-sensor based method for estimating the acoustic intensity, the phase and amplitude gradient estimation (PAGE) method, is presented. This method uses the same hardware as the standard finite-difference method, but does not suffer from the frequency-dependent bias inherent to the finite-difference method. A detailed derivation of the PAGE method and the finite-difference method is presented. Both methods are then compared using simple acoustic fields. The ability to unwrap the phase component of the PAGE method is discussed, which leads to accurate intensity estimates above previous frequency limits. The uncertainties associated with both methods of estimation are presented. It is shown that the PAGE method provides more accurate intensity estimates over a larger frequency bandwidth.
Urinary tract injuries are unfortunate complications of pelvic surgery. With the increasing popularity of minimally invasive surgery, a thorough understanding of electrosurgical instrumentation and their thermal spread is important to reduce patient injuries.The index patient was a 50 year old woman who underwent a supracervical hysterectomy 5 years prior to her presentation with pelvic pain and dysuria. When her symptoms failed to improve despite antibiotic and analgesic therapy, an abdominal CT scan revealed an ovarian cyst and ascites. A subsequent laparoscopy disclosed the presence of a bladder fistula and a diagnosis of urinary ascites was made. The patient then underwent a subsequent bladder fistula repair.Vesicoperitoneal fistulae (VPF) are rare and should be included in the differential diagnosis of the patient with acute onset ascites following gynecologic surgery. This case is the first case report of a VPF occurring 5 years following surgery.
Advanced technical courses often suffer from a lack of interactive materials. Common tools to remedy this deficiency include MATLAB and Mathematica, both of which can be prohibitively expensive to obtain outside of the university environment. Python is a scripted language that is easy to read and use and is rapidly emerging as a lingua franca for scientific computing due to the flexibility and facility of the language, the large and active community, and the large number of high quality scientific libraries that are available in Python. Python provides a free and open source tool to develop classroom materials that students can modify and extend. We discuss the use of Python in teaching advanced topics in mathematics, physics, and acoustics. Examples are drawn from courses in acoustics, mechanics, and mathematical and computational physics
Acoustic measurements of a static GEM-60 solid motor test firing were taken as part of a continuing effort to characterize the aeroacoustic source regions and noise environment around launch vehicles. Multiple 2D intensity probes, consisting of four coplanar microphones, were used in the measurement. Two intensity estimation techniques have been applied to the data: the finite difference p-p method, and the new phase and amplitude gradient estimation (PAGE) method. We will present and compare results from both methods and compare to measurements made at past test firings. It appears that the PAGE method for estimating acoustic intensity provides usable results over a larger frequency bandwidth.
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