J. Sousa Ramos

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BACKGROUND The rate of acute rejection (AR) has decreased significantly, but whether this is associated with improvement in long-term graft survival is controversial. METHODS We analyzed 1445 consecutive adult deceased donor kidney transplant recipients from 1985 to 2005, over two periods (1985-1995 vs. 1996-2005) to compare long-term graft survival. (More)
A 50-year-old patient developed a left temporal fibrochondrosarcoma 27 years after radiation therapy for a suspected pituitary adenoma. The long latency between the irradiation and the development of the sarcoma and the histological nature of the tumour are unusual features for a malignant radiation-induced intracranial tumour. The histogenesis of(More)
BACKGROUND Methods that predict prognosis and response to therapy in pulmonary hypertension (PH) are lacking. We tested whether the noninvasive estimation of hemodynamic parameters during 6-minute walk test (6MWT) in PH patients provides information that can improve the value of the test. METHODS We estimated hemodynamic parameters during the 6MWT using a(More)
A case of a previously undescribed malformation of the inferior vena cava is reported: there was distal normoposition and proximal transposition, with anterior crossing over the aorta; the right renal vein flowed into the inferior vena cava located on the left, after crossing over the anterior face of the aorta. This anomaly was shown by echography and(More)
Nonlinear dynamics and chaos theory have been used in neurophysiology with the aim to understand the complex brain activity from electroencephalographic (EEG) signals. Although linear methods have been the most used in EEG analysis, nonlinear approaches have been increased their presence because they reveal aspects that cannot be measured from linear(More)
The dynamics of Steffesen-type methods, using a graphical tool for showing the basins of attraction, is presented. The study includes as particular cases, Steffesen-type modifications of the Newton, the two-steps, the Chebyshev, the Halley and the super– Halley iterative methods. The goal is to show that if we are interesting to preserve the convergence(More)
Consider the one-parameter family of real quadratic maps fμ : [0, 1] → [0, 1] defined by fμ(x) = μx(1−x), with μ ∈ [0, 4]. Using Milnor-Thurston’s kneading theory [14], J. Guckenheimer [5] has classified up to topological conjugacy, a certain class of maps which includes the quadratic family. The idea of kneading theory is to encode information about the(More)
One of the interesting complex behaviors in many cell membranes is bursting, in which a rapid oscillatory state alternates with phases of relative quiescence. Although there is an elegant interpretation of many experimental results in terms of nonlinear dynamical systems, the dynamics of bursting models is not completely described. In the present paper, we(More)