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Publications

Publications by Vitor Manuel Filipe

2009

Web platform architecture to support the Geographic Information System of the University of Tras-os-Montes and Alto Douro Campus

Authors
Almeida, J; Fernandes, H; Filipe, V; Barroso, J;

Publication
2009 INTERNATIONAL CONFERENCE ON NEW TRENDS IN INFORMATION AND SERVICE SCIENCE (NISS 2009), VOLS 1 AND 2

Abstract
The spread of the Internet throughout society has sparked a revolution in the way many areas of knowledge are promoted. Geographic Information Systems (GIS) are, potentially, such an area. By distributing geospatial information and ways to manipulate it across the Web, a universal broadcast service is achieved, allowing users to access data anywhere. Geographic Information (GI) is usually the realm of specialized companies, and the client's role is often limited to consuming such information. This project aims to conceive a prototype of an architecture that allows the visualization of the Geographic Information System of University of Tras-os-Montes and Alto Douro. This prototype will also be used to feed other systems, also being developed, like navigation systems based on GPS to help people with disabilities, namely, blind users.

2012

Measuring displacement fields by cross-correlation and a differential technique: experimental validation

Authors
Xavier, J; Sousa, AMR; Morais, JJL; Filipe, VMJ; Vaz, M;

Publication
OPTICAL ENGINEERING

Abstract
A digital image correlation (DIC) algorithm for displacement measurements combining cross-correlation and a differential technique was validated through a set of experimental tests. These tests consisted of in-plane rigid-body translation and rotation tests, a tensile mechanical test, and a mode I fracture test. The fracture mechanical test, in particular, was intended to assess the accuracy of the method when dealing with discontinuous displacement fields, for which subset-based image correlation methods usually give unreliable results. The proposed algorithm was systematically compared with the Aramis (R) DIC-2D commercial code by processing the same set of images. When processing images from rigid-body and tensile tests (associated with continuous displacement fields), the two methods provided equivalent results. When processing images from the fracture mechanical test, however, the proposed method obtained a better qualitative description of the discontinuous displacements. Moreover, the proposed method gave a more reliable estimation of both crack length and crack opening displacement of the fractured specimen.(C) (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.OE.51.4.043602]

2002

Motion of the foot and ankle during the stance phase in rats

Authors
Varejao, ASP; Cabrita, AM; Meek, MF; Bulas Cruz, J; Gabriel, RC; Filipe, VM; Melo Pinto, P; Winter, DA;

Publication
MUSCLE & NERVE

Abstract
Computerized analysis of rat gait is becoming an invaluable technique used by some peripheral nerve investigators for the evaluation of function. In this article we describe the use of a biomechanical model of the foot and ankle that allows a quantitative assessment and description of the ankle angle, reflecting plantarflexion and dorsiflexion during the stance phase of gait. Kinematic data of 144 trial walks from 36 normal rats were recorded with a high-speed digital image camera at 225 images per second. The ankle angular changes associated with the specific temporal events of foot placement on the ground through the stance phase were assessed. The information obtained was used to propose a new subdivision of the stance phase in the rat into three major components. This approach will provide a helpful research tool to analyze gait data that rely on the accurate determination of spatiotemporal foot events. (C) 2002 Wiley Periodicals, Inc.

2003

Ankle kinematics to evaluate functional recovery in crushed rat sciatic nerve

Authors
Varejao, ASP; Cabrita, AM; Meek, MF; Bulas Cruz, J; Filipe, VM; Gabriel, RC; Ferreira, AJ; Geuna, S; Winter, DA;

Publication
MUSCLE & NERVE

Abstract
Peripheral nerve researchers frequently use the rat sciatic nerve crush model in order to test different therapeutic approaches. The purpose of this study was to determine the sequence of changes after an axonotmetic injury by means of a biomechanical model of the foot and ankle, and compare them with walking track analysis, over a fixed period of time. A kinematic analysis program was used to acquire ankle motion data for further analysis. Although repeated measures analysis of variance showed significant cumulative changes induced by the crush lesion for both ankle kinematic parameters and sciatic functional index, post-hoc multiple comparisons by the Student-Neuman-Keuls test revealed significant differences between week 0 and week 8 only for ankle kinematics. These results are of importance in showing the superiority of ankle kinematics in detecting small biomechanical deficits related to hyperexcitability of the plantarflexor muscles, in contrast with walking track analysis, which showed full motor functional recovery 8 weeks after the crush lesion.

2003

Toe out angle: a functional index for the evaluation of sciatic nerve recovery in the rat model

Authors
Varejao, ASP; Cabrita, AM; Geuna, S; Melo Pinto, P; Filipe, VM; Gramsbergen, A; Meek, MF;

Publication
EXPERIMENTAL NEUROLOGY

Abstract
In experimental peripheral nerve studies, the rat sciatic nerve model is widely used to examine functional outcome following nerve injury and repair. A variety of evaluation methods exist in the literature, but an adequate selection continues to be a critical point for the researcher. Rats with sciatic nerve injury typically ambulate with an external rotation of the foot. A new functional assessment instrument, the toe out angle (TOA) is quantified using computerized gait analysis. We compared Sciatic Functional Index (SFI) with TOA parameter after peripheral nerve transection and entubulation repair. We found a good correlation between SFI and TOA measurements in terms of predicting functional recovery. Moreover, the TOA provides information on the biomechanical consequences of the external rotation of the foot in the stance phase of walking.

2007

Contribution of cutaneous inputs from the hindpaw to the control of locomotion in rats

Authors
Varejao, ASP; Filipe, VM;

Publication
BEHAVIOURAL BRAIN RESEARCH

Abstract
The influence of reduced feedback from the cutaneous receptors in the hindpaw in rat locomotion is still unclear. To evaluate this question., we conducted a detailed hindlimb kinematic analysis in animals, which suffered complete loss of thermal sensation. Two-dimensional hindlimb kinematics, temporal and spatial measurements. and walking track analysis were performed in rats before and during hypothermic anesthesia. The walking velocity. duration of the step cycle and stance phase, and stride length between the two testing conditions were statistically indistinguishable. Swing phase duration was significantly decreased during sensory loss. Analysis of angular motion revealed an increased hip and knee extension and an ankle joint with increased flexion during the step cycle under plantar anesthesia. Also after plantar cooling, the hip and knee angular velocity was significantly affected along the step cycle. The remarkably geometric similarity of the angle-angle plots obtained in our experiments reflected an interjoint coordination: however. the interpretation of the cyclogram perimeter revealed a larger excursion by the ankle and hip in their respective joint spaces in rats deprived of sensation. Examination of the horizontal position of the ankle with respect to the hip and the extension before toe-off revealed no major changes. whereas, there was a slight decrease in distance of the hip to the ground during sensory loss. Also, the walking tracks revealed a significant functional deficit following reduced cutaneous information of the plantar aspect of the hindpaw. We therefore conclude that sensory feedback from the hindpaw is important in the maintenance of normal rat locomotion.

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