Surface shape reconstruction from phaseless scattered acoustic data using a random forest algorithm.

Recent studies have demonstrated that acoustic waves can be used to reconstruct the roughness profile of a rigid scattering surface. In particular, the use of multiple microphones placed above a rough surface as well as an analytical model based on the linearised Kirchhoff integral equations provides a sufficient base for the inversion algorithm to estimate surface geometrical properties. Prone to fail in the presence of high noise and measurement uncertainties, the analytical approach may not always be suitable in analysing measured scattered acoustic pressure. With the aim to improve the robustness of the surface reconstruction algorithms, here it is proposed to use a data-driven approach through the application of a random forest regression algorithm to reconstruct specific parameters of one-dimensional sinusoidal surfaces from airborne acoustic phase-removed pressure data. The data for the training set are synthetically generated through the application of the Kirchhoff integral in predicting scattered sound, and they are further verified with data produced from laboratory measurements. The surface parameters from the measurement sample were found to be recovered accurately for various receiver combinations and with a wide range of noise levels ranging from 0.1% to 30% of the average scattered acoustical pressure amplitude.

Exposure of the Calcaneus in the Sinus Tarsi Approach Versus the Lateral Extensile Approach: A Cadaveric Study.

BACKGROUND: The lateral extensile approach (LEA) is an operative approach for calcaneal fractures. High rates of wound complications have led to alternative approaches such as the sinus tarsi approach to grow in popularity. The LEA affords substantial visualization of the calcaneus. This visualization has never been compared in a quantitative manner with the sinus tarsi approach (STA). We aim to quantify the calcaneal visualization afforded by STA and LEA. METHODS: Seven pair-matched, fresh-frozen, below-knee cadaver extremities were included. For each pair, one side received an LEA and the other side received an STA. RESULTS: There were no statistically significant differences in the articular surfaces accessible between the 2 approaches. The total calcaneal surface area accessible was 3107.08 mm2 for LEA and 1444.19 mm2 for STA (P = .02). The LEA allowed better exposure to the lateral wall (P = .01) and the dorsal tuberosity of the calcaneus (P = .04). CONCLUSION: The STA allows for equivalent articular surface exposure when compared with the LEA. Although LEA allows for greater exposure of the lateral wall and dorsal tuberosity, direct visualization of these structures may not warrant the higher risk of wound complications. Surgeons should consider these differences when choosing an operative approach in the treatment of calcaneal fractures.Level III.

A comparison of male sex workers in Prague: Internet escorts versus men who work in specialized bars and clubs.

Prague, the Czech Republic, is a popular sex tourism destination where sex work is decriminalized and young men offer sexual services at low prices relative to countries in Western Europe. This quantitative survey aimed to identify some of the demographic characteristics of these young men and their experiences in the sex industry. Internet escorts (N = 20) and sex workers in bars and clubs (N = 20) completed the survey anonymously in spring 2011. The results showed that sex workers in clubs often had troubled pasts and were forced into sex work to survive. They also reported incidents of violence, serious alcohol and drug use, as well as frequent gambling. The larger group of sex workers in Prague is made up of Internet escorts who have backgrounds that are not atypical for the average Czech youth. They had fewer problems with drugs and alcohol but were twice as likely as sex workers in bars and clubs to be victims of violent crime. Plans for interventions to help those who would change their line of work, as well as the importance of sociocultural context in understanding sex workers, are discussed.

Outcome based on management for duodenal adenomas: sporadic versus familial disease.

INTRODUCTION: Management and outcomes for duodenal adenomas may vary based on etiology, familial versus sporadic. We reviewed the records of patients managed at our institution for duodenal adenomatous polyps for the 20-year period ending July 2006. DISCUSSION: Methods of polyp resection (endoscopic, local surgical resection, or definitive surgical resection) within both sporadic and familial patient groups were compared. Patients with known cancer were excluded. Two hundred seventy-eight patients with duodenal polyps were followed during this time period: 110 patients (39.6%) with sporadic polyps and 168 (60.4%) with familial adenomatous polyposis (FAP). Sporadic patients presented at a mean age of 66.5 years. Endoscopic resection was attempted in 44 patients (40%) with morbidity in 9% and local recurrence rate of 52% with a mean follow-up of 43 months. Surgical resection was performed in 46 patients (42%): 27 by definitive resection and local resection in 19. At a mean follow-up of 41 months, there were no local recurrences in the patients treated by definitive resection and six recurrences (32%) after local resection. Morbidity was 39%. There was a significant difference in local recurrence when comparing definitive resection to both endoscopic and local resection (p<0.001, p=0.002, respectively), but no significant difference between endoscopic and local excision (p=0.13). Cancer was discovered in the surgical specimens of 11 patients (24%) with benign preoperative biopsies. FAP patients began surveillance at a mean age of 39.5 years, and mean surveillance duration was 100 months. Endoscopic resection/ablation was attempted in 40 patients (24%) with a morbidity of 7.5%. With a mean follow-up of 77.5 months, the local recurrence rate was 72.5%. Surgical resection was performed in with local recurrence rates of 9% and 100%, respectively. Surgical morbidity was 48%. Local recurrence was significantly lower following definitive resection compared to endoscopic or local resection (p<0.001), but there was no difference in local recurrence between the latter two groups (p=0.29). Four patients (8%) undergoing surgery were discovered to have invasive cancer despite benign endoscopic biopsies. In summary, endoscopic and local surgical management for both sporadic and familial duodenal polyps are associated with a high rate of local recurrence. Definitive resection in the form of pancreaticoduodenectomy, pancreas-sparing duodenectomy, or segmental duodenectomy offers the best chance for polyp eradication and prevention of carcinoma, regardless of polyp etiology.