Repositório IC-Online
Institution's Scientific Repository
Recent Submissions
Numerical Calculations in Tissue Engineering
Publication . Almeida, Henrique de Amorim; Bártolo, Paulo J.
The design of optimized scaffolds for tissue engineering is a key topic of research, as the complex macro- and micro- architectures required for a scaffold depends not only on the mechanical properties, but also on the physical and molecular queues of the surrounding tissue within the defect site. Thus, the prediction of optimal features for tissue engineering scaffolds is very important for its mechanical, vascular or topological properties. The relationship between high scaffold porosity and high mechanical properties is contradictory, as it becomes even more complex due to the scaffold degradation process. A scaffold design strategy was developed, based on the finite element method, to optimise the scaffold design regarding the mechanical and vascular properties as a function of porosity. Scaffolds can be considered as a LEGO structure formed by an association of small elementary units or blocks. In this research work, two types of family elementary scaffold units were considered: non-triple periodic minimal surfaces and triple periodic minimal surfaces that describe natural existing surfaces. The main objective of this work is to present the undergoing research based on numerical simulations for the evaluation and prediction of the scaffold's behaviour under structural and vascular loading, and its topological optimisation.
Lossless light-field compression using reversible colour transformations
Publication . Santos, Joao M.; Pedro A. A. Assuncao; Cruz, Luis A. da Silva; Luís Távora; Fonseca-Pinto, Rui; Sergio M. M. Faria
Recent advances in Light Field acquisition and rendering are pushing research efforts towards increasingly efficient methods to encode this particular type of data. Light Field image compression is of the utmost importance, not only due to the large amount of data required for its representation but also due to quality requirements of many applications and computational
photography methods. This paper presents a research study about the impact of reversible colour transformations and alternative data arrangements in Light Field lossless coding. The experimental results indicate that the RCT reversible transform consistently achieves the highest compression performance across all data arrangements and lossless encoders. In particular, the
best results are obtained with MRP when encoding the stack of sub-aperture images using a spiral scan order, achieving 6.41 bpp, on average.
HESITA(te) in Portuguese
Publication . Candeias, Sara; Celorico, Dirce; Proença, Jorge; Veiga, Arlindo; Lopes, Carla, Carla Alexandra Calado; Perdigão, Fernando
Hesitations, so-called disfluencies, are a characteristic of spontaneous speech, playing a primary role in its structure, reflecting aspects of the language production and the management of inter-communication. In this paper we intend to present a database of hesitations in European Portuguese speech - HESITA - as a relevant base of work to study a variety of speech phenomena. Patterns of hesitations, hesitation distribution according to speaking style, and phonetic properties of the fillers are some of the characteristics we extrapolated from the HESITA database. This database also represents an important resource for improvement in synthetic speech naturalness as well as in robust acoustic modelling for automatic speech recognition. The HESITA database is the output of a project in the speech-processing field for European Portuguese held by an interdisciplinary group in intimate articulation between engineering tools and experience and the linguistic approach.
An observation on n-permutability
Publication . Martins-Ferreira, Nelson; Rodelo, Diana; Van der Linden, Tim
We prove that in a regular category all reflexive and transitive relations are symmetric if and only if every internal category is an internal groupoid. In particular, these conditions hold when the category is n-permutable for some n.
Estudo preliminar da saúde oral de desportistas praticantes de boxe
Publication . Caciones, Adriana; Antunes, Margarida; Assunção, Victor; Albuquerque, Teresa; Luis, Henrique
Objetivos Caracterizar o estado de saúde oral de praticantes de boxe; conhecer a frequência de utilização de protetores bucais e os efeitos na saúde oral dos praticantes desta modalidade desportiva; comparar o uso de protetores bucais e de efeitos na saúde oral entre praticantes de boxe de manutenção e de competição.
Métodos: A população-alvo foi constituída por uma amostra de conveniência dos praticantes de boxe amador na Escola de Boxe de Lisboa. A recolha de dados foi realizada através de questionário, observação da cavidade oral avaliando os índices CPO-D, gengival (IG) e higiene oral simplificado (IHO-S), e palpação da articulação temporo-mandibular. Os dados foram analisados com teste de V de Cramer (α=0,05).
Resultados: Amostra constituída por 36 indivíduos (18-65 anos), maioritariamente do sexo masculino. A maioria utiliza protetores bucais (89%), sendo as “Boil and Bite” os mais populares. As alterações provocadas na cavidade oral verificaram-se, maioritariamente, ao nível da ATM, com 33% dos praticantes referindo dor na articulação e 25% dificuldade em abrir a boca. Nos hábitos de higiene oral, a maioria indicou escovar 2 a 3 vezes ao dia, utilizar meios de remoção interdentária e realizar consultas de saúde oral regularmente. Na observação intraoral, obtiveram-se os seguintes valores médios: 5,66 no CPO, 2,59 no IHO-S e 0,59 no IG.