Isabel N. Figueiredo

Automated Polyp Detection in Colon Capsule Endoscopy

Colorectal polyps are important precursors to colon cancer, a major health problem. Colon capsule endoscopy is a safe and minimally invasive examination procedure, in which the images of the intestine are obtained via digital cameras on board of a small capsule ingested by a patient. The video sequence is then analyzed for the presence of polyps. We propose an algorithm that relieves the labor of a human operator analyzing the frames in the video sequence. The algorithm acts as a binary classifier, which labels the frame as either containing polyps or not, based on the geometrical analysis and the texture content of the frame.We assume that the polyps are characterized as protrusions that are mostly round in shape. Thus, a best fit ball radius is used as a decision parameter of the classifier. We present a statistical performance evaluation of our approach on a data set containing over 18 900 frames from the endoscopic video sequences of five adult patients. The algorithm achieves 47% sensitivity per frame and 81% sensitivity per polyp at a specificity level of 90%. On average, with a video sequence length of 3747 frames, only 367 false positive frames need to be inspected by an operator.

A class of contact and friction dynamic problems in thermoelasticity and in thermoviscoelasticity

Abstract In this work we consider a class of dynamical contact problems with friction in the framework of thermoelasticity and thermoviscoelasticity theories. The results are valid for both elastic and viscoelastic materials (with short and long memory terms), for contact conditions, of the power law type, both on the normal and on the tangential stress components, including also unilateral contact conditions on the temperature or heat flux. Some existence and nonexistence; unicity and nonunicity results are presented, as a function of the relationship between the elasticity, viscous, thermal and contact coefficients. This work extends previous results of Duvaut and Lions and of Martins and Oden for the elastodynamics case. We use a penalty method in order to take into account the variational inequality equations and a regularization method for the approximation of the friction functional.

On the attainable eigenvalues of the Laplace operator

We consider the subset E of

Automatic Polyp Detection in Pillcam Colon 2 Capsule Images and Videos: Preliminary Feasibility Report

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A Complementarity Eigenproblem in the Stability Analysis of Finite Dimensional Elastic Systems with Frictional Contact

of all points whose first and second components, respectively, coincide with the first and second eigenvalues of the Laplace operator

Computer-assisted bleeding detection in wireless capsule endoscopy images

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Automated lesion detectors in retinal fundus images

with zero boundary conditions on domains of

A Generalized Piezoelectric Bernoulli–Navier Anisotropic Rod Model

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Mucosal region detection and 3D reconstruction in wireless capsule endoscopy videos using active contours

with prescribed measure. We show that the set E is closed in

Exploring smartphone sensors for fall detection

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