Topology optimization of 2D elastic structures using boundary elements

Topological optimization provides a powerful framework to obtain the optimal domain topology for several engineering problems. The topological derivative is a function which characterizes the sensitivity of a given problem to the change of its topology, like opening a small hole in a continuum or changing the connectivity of rods in a truss. A numerical approach for the topological optimization of 2D linear elastic problems using boundary elements is presented in this work. The topological derivative is computed from strain and stress results which are solved by means of a standard boundary element analysis. Models are discretized using linear elements and a periodic distribution of internal points over the domain. The total potential energy is selected as cost function. The evaluation of the topological derivative is performed as a post-processing procedure. Afterwards, material is removed from the model by deleting the internal points and boundary nodes with the lowest values of the topological derivate. The new geometry is then remeshed using a weighted Delaunay triangularization algorithm capable of detecting "holes" at those positions where internal points and boundary points have been removed. The procedure is repeated until a given stopping criterion is satisfied. The proposed strategy proved to be flexible and robust. A number of examples are solved and results are compared to those available in the literature. © 2007 Elsevier Ltd. All rights reserved.Fil: Carretero Neches, L.. Universidad de Sevilla; EspañaFil: Cisilino, Adrian Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Endovascular treatment of acute renal failure secondary to bilateral renal artery thrombosis in Leriche syndrome

A patient with chronic ischemic arterial disease was admitted to a hospital with anuria. Aortoiliac occlusion below AMS output affecting both renal arteries was diagnosed. Percutaneous angioplasty and right renal artery stenting were performed, achieving gradual recovery of renal function.Póster presentado en: CIRSE 2013, celebrado en Barcelona (España) del 14-18 de septiembre de 201

Complications of endomyocardial biopsy in children

AbstractOBJECTIVESTo evaluate the incidence of, and risk factors for, complications of endomyocardial biopsy in children.BACKGROUNDEndomyocardial biopsy (EMB) is a low risk procedure in adults, but there is a paucity of data with regard to performing this procedure in children.METHODSRetrospective review of the morbidity and mortality of 1,000 consecutive EMB procedures.RESULTSOne thousand EMB procedures (right ventricle 986, left ventricle 14) were performed on 194 patients from July 1987 through March 1996. Indications for EMB included heart transplant rejection surveillance (846) and the evaluation of cardiomyopathy or arrhythmia for possible myocarditis (154). Thirty-seven (4%) procedures were performed on patients receiving intravenous inotropic support. There was one biopsy related death, secondary to cardiac perforation, in a two-week-old infant with dilated cardiomyopathy. There were nine perforations of the right ventricle, eight occurring in patients with dilated cardiomyopathy and one in a transplant recipient. The transplant patient did not require immediate intervention; two patients required pericardiocentesis alone, and six underwent pericardiocentesis and surgical intervention. All nine perforations were from the femoral venous approach (p < 0.01). Multivariate analysis demonstrated that the greatest risk of perforation occurred in children being evaluated for possible myocarditis (p = 0.01) and in those requiring inotropic support (p < 0.01). Other complications included arrhythmia (5) and single cases of coronary-cardiac fistula, flail tricuspid leaflet, pneumothorax, hemothorax, endocardial stripping and seizure.CONCLUSIONSRisk of endomyocardial biopsy is highest in sick children with suspected myocarditis on inotropic support. However, EMB can be performed safely with very low morbidity in pediatric heart transplant recipients