MmWave scattering properties of roads on rough asphalt and concrete surfaces

In this work, a synthetic aperture radar setup is used for analyzing the mmWave scattering of road surfaces in the automotive 77 GHz band in the laboratory. With this setup, samples of concrete roads in two different surface conditions are investigated, determining the variances in reflectivity depending on material composition and surface structure. Afterward, the distribution of these variations is fitted using probability density functions, namely normal and rayleigh distribution fits. Consequently, the diffuse scattering behavior of concrete roads can be described mathematically. Additionally, previously presented porous asphalt roads are compared and fitted analogously to get a summary of the scattering for all common road surfaces in Germany. Furthermore, a validation of the measurement and the processing by analyzing particularly generated reference samples is performed.</p

Primary laparoscopic pull-through for Hirschsprung\u27s disease in infants and children.

Between November 1993 and September 1994, 12 primary laparoscopic colon pull-through procedures were performed in infants and children. The patients\u27 ages ranged from 3 days to 6 years. The primary diagnosis in all 12 patients was Hirschsprung\u27s disease. All children had their operations without construction of preoperative or postoperative colostomy. Three 5-mm abdominal wall ports were used for access to the peritoneal cavity. The sigmoid colon and proximal rectum were mobilized laparoscopically. A submucosal sleeve was developed transanally to meet the dissection from above. The colon was then pulled down in continuity, divided above the transition zone, and secured to the anal mucosa 5 to 10 mm above the pectinate line. Mean postoperative stay was 4 days. Laparoscopic visualization provides clear delineation of pelvic structures even in small infants. Laparoscopic pull-through requires no more time than similar open procedures, averaging just over 2 hours. The morbidities associated with colostomy formation and closure and the inconvenience of colostomy care are avoided with a one-stage technique. These benefits combined with the advantages of minimally invasive surgery make primary laparoscopic pull-through a potential advance in the surgical treatment of Hirschsprung\u27s disease