Stereotactic core biopsy of breast microcalcifications. Aid to diagnosis?]

We assessed the accuracy with which stereotactic core biopsy of breast microcalcifications helps to justify follow-up or indicate required surgical planning. Eighty-nine patients underwent stereotactic breast biopsy performed with large core needles. Histopathologic findings of microbiopsies were correlated with radiological findings, with follow up and with surgical findings. Agreement between radiological and histopathologic findings on biopsies was obtained in 86% for benign results. Even in the case of benign radiological findings, the histological results of microbiopsies required a surgical biopsy justified in 10% of cases. Radiologically suspicious or malignant microcalcifications were correlated with 35% benign and 65% malignant histologies on biopsies. The positive predictive value, negative predictive value and accuracy were respectively 93%, 86% and 95%. Invasive lesions were found on microbiopsies in 39% of excised malignant lesions. Multifocal lesions were proved on microbiopsies in 50% of all excised carcinomas. Microbiopsies help to disclose malignant lesions undetected on radiological analysis, and may obviate diagnostic surgical biopsy in many cases.     

Nissen fundoplication by laparoscopy

Short term results following laparoscopic Nissen fundoplication were evaluated in 31 patients with symptomatic gastroesophageal reflux. 6 were females and 26 males, and they ranged in age from 5 months to 64 years (mean: 4.9 years in 19 younger than 18 years, and 39.3 years in 12 adults). Most of the adults who complained of pain and heartburn underwent pH monitoring, endoscopy, and manometry as needed. Milk scan was the most useful diagnostic tool for the evaluation of the children, who suffered mainly from gastroesophageal-related pulmonary disease. Indications for laparoscopic operation were identical with those for conventional open Nissen fundoplication. 1 case of dysautonomia died postoperatively; the rate of complications, mostly minor, was 22.5%. 3 patients required conversion to open Nissen fundoplication due to cardiorespiratory instability secondary to pneumothorax in 2, and to esophageal perforation in the third. 5 adults developed temporary dysphagia. 3 children had only partial improvement in their pulmonary disease following the operation, while the other 15 had complete relief. The total time for the laparoscopic operation averaged 245 minutes in adults, and 228 in children. Discharge was usually on the fourth postoperative day in adults (mean: 6.0 days). Regurgitation and heartburn were cured in 10 out of 11 adults (91%). All parents of children were satisfied. Symptomatic outcomes following laparoscopic Nissen fundoplication compare favorably with those of open surgery with respect to mortality, complications, and outcome.     

Parallel Large Scale High Accuracy Navier-Stokes Computations on Distributed Memory Clusters

We present a highly scalable parallelization of a high-accuracy 3D serial multiblock Navier-Stokes solver. The code solves the full Navier-Stokes equations and is capable of performing large-scale computations for practical configurations in an industrial enviroment. The parallelization strategy is based on the geometrical domain decomposition principle, and on the overlapped communication and computation concept. The important advantage of the strategy is that the suggested type of message-passing ensures a very high scalability of the algorithm from the network point of view, because, on the average, the communication work per processor is not increased if the number of processors is increased. The parallel multiblock-structured Navier-Stokes solver based on the parallel virtual machine (PVM) routines was implemented on 106-processors distributed memory cluster managed by the MOSIX software package. Analysis of the results demonstrated a high level of parallel efficiency (speed up) of the computational algorithm. This allowed the reduction of the execution time for large-scale computations employing 10 million of grid points, from an estimated 46 days on the SGI ORIGIN 2000 computer (in the serial single-user mode) to 5–6 hours on 106-processors cluster. Thus, the parallel multiblock full Navier-Stokes code can be successfully used for large-scale practical aerodynamic simulations of a complete aircraft on millions-points grids on a daily basis, as needed in industry.     

Strain rate and oxidation effects on crack initiation at 600 and 650 °C in a nickel-based superalloy

Nickel-based superalloys are sensitive to an oxidation-assisted intergranular crack (OAIC) growth mechanism. Crack initiation during slow strain rate tensile tests is investigated at 600 and 650 °C, at different strain rates, with or without oxidation on a direct-aged material. A V-shaped sample geometry is used to promote damage initiation for a specific stress triaxiality. The critical mechanical loading paths inducing intergranular crack initiation as well as the effect of oxidation are discussed.