RESUMEN
The dynamical interplay of coupled non-identical chaotic oscillators gives rise to diverse scenarios. The incoherent dynamics of these oscillators lead to the structural impairment of attractors in phase space. This paper investigates the couplings of Lorenz-Rössler, Lorenz-HR, and Rössler-HR to identify the dominant attractor. By dominant attractor, we mean the attractor that is less changed by coupling. For comparison and similarity detection, a cost function based on the return map of the coupled systems is used. The possible effects of frequency and amplitude differences between the systems on the results are also examined. Finally, the inherent chaotic characteristic of systems is compared by computing the largest Lyapunov exponent. The results suggest that in each coupling case, the attractor with the greater largest Lyapunov exponent is dominant.
RESUMEN
BACKGROUND: Solid pseudopapillary tumor of the pancreas (SPT) is a rare tumor of low malignant potential, mostly described in young women. MATERIALS AND METHODS: In this retrospective study from January 2000 - December 2010, there were 50 pancreatic tumors. In this period, four SPTs were encountered, which were analyzed with respect to clinical, imaging, histopathological, and immunohistochemical findings. RESULTS: There was a female preponderance with mean age of 22.2 years. Two of the tumors were located in head of the pancreas and two in the body and tail region. On imaging, majority were large cystic tumors. Histopathologically, they exhibited extensive necrosis and presence of pseudo papillae in viable areas. Immunohistochemically, they were positive for alpha-1-anti-trypsin, alpha-1-anti-chymotrypsin, vimentin, CD10, and CD99. Progesterone receptor and p53 exhibited mild positivity in all of the four cases, whereas neuron specific enolase (NSE), synaptophysin, and chromogranin showed focal positivity in one case. CONCLUSION: Despite its non-specific clinical, imaging, and even immunohistochemical features, characteristic gross and microscopic findings provide reliable diagnosis of SPTs.
RESUMEN
CONTEXT: Synchronous malignancies affecting both the major and minor papilla are rare and are usually of endocrine origin. CASE REPORT: A 60-year-old female presented with a two-week history of progressive jaundice and pruritus. Evaluation revealed features of a periampullary malignancy. A Whipple pancreaticoduodenectomy was done. There was a growth in the ampulla of Vater and another in the region of the minor duodenal papilla. On histopathology, both lesions were adenocarcinomas. CONCLUSION: Although rare, synchronous adenocarcinomas can occur in the major and minor papilla.
