RESUMO
Ball collisions in milling devices are governed by complex dynamics ruled by impredictable impulsive forces. In this paper, nonlinear dynamics techniques are employed to analyze the time series describing the trajectory of a milling ball in an empty container obtained from a numerical model. The attractor underlying the system dynamics was reconstructed by the time delay method. In order to characterize the system dynamics the calculation of the spectrum of Lyapunov exponents was performed. Six Lyapunov exponents, divided into two terns with opposite sign, were obtained. The detection of the positive tern demonstrates the occurrence of the hyperchaotic qualities of the ball motion. A fractal Lyapunov dimension, equal to 5.62, was also obtained confirming the strange features of the attractor. (c) 1999 American Institute of Physics.
RESUMO
We report on the case of a 32 years old man submitted to right eye enucleation twelve years before for a choroidal melanoma. We observe a metastases located in the left adrenal gland. The blood-tests, the TAC of the abdomen did not show other localizations, while during laparotomy were discovered metastases in the pancreas and in the omentum. In this case, the age of tumor's development, the age of clinical manifestation, the period between the enucleation and the appearance of the metastases and their localization are exceptions to the normal biological behaviour of the choroidal melanoma.
Assuntos
Neoplasias das Glândulas Suprarrenais/secundário , Neoplasias da Coroide/patologia , Melanoma/secundário , Adulto , Humanos , MasculinoRESUMO
Many children have dermatoses involving the feet. Such problems are often misdiagnosed as tinea pedis, which is relatively uncommon in this age group. On the other hand, tinea pedis should not be ignored as a diagnostic possibility just because of its infrequent occurrence. Six cases are reported to demonstrate that this diagnosis will be missed if appropriate laboratory studies are not done as a part of the evaluation of these dermatoses.
