Lighting conditions and optical filters effects on visual performance of speleologists exposed to cave environments

The aim of this study is to evaluate lighting conditions and speleologists’ visual performance using optical filters when exposed to the lighting conditions of cave environments. A crosssectional study was conducted. Twenty-three speleologists were submitted to an evaluation of visual function in a clinical lab. An examination of visual acuity, contrast sensitivity, stereoacuity and flashlight illuminance levels was also performed in 16 of the 23 speleologists at two caves deprived of natural lightning. Two organic filters (450 nm and 550 nm) were used to compare visual function with and without filters. The mean age of the speleologists was 40.65 (± 10.93) years. We detected 26.1% participants with visual impairment of which refractive error (17.4%) was the major cause. In the cave environment the majority of the speleologists used a head flashlight with a mean illuminance of 451.0 ± 305.7 lux. Binocular visual acuity (BVA) was -0.05 ± 0.15 LogMAR (20/18). BVA for distance without filter was not statistically different from BVA with 550 nm or 450 nm filters (p = 0.093). Significant improved contrast sensitivity was observed with 450 nm filters for 6 cpd (p = 0.034) and 18 cpd (p = 0.026) spatial frequencies. There were no signs and symptoms of visual pathologies related to cave exposure. Illuminance levels were adequate to the majority of the activities performed. The enhancement in contrast sensitivity with filters could potentially improve tasks related with the activities performed in the cave.

Advanced side information creation techniques and framework for Wyner-Ziv video coding

Recently, several distributed video coding (DVC) solutions based on the distributed source coding (DSC) paradigm have appeared in the literature. Wyner-Ziv (WZ) video coding, a particular case of DVC where side information is made available at the decoder, enable to achieve a flexible distribution of the computational complexity between the encoder and decoder, promising to fulfill novel requirements from applications such as video surveillance, sensor networks and mobile camera phones. The quality of the side information at the decoder has a critical role in determining the WZ video coding rate-distortion (RD) performance, notably to raise it to a level as close as possible to the RD performance of standard predictive video coding schemes. Towards this target, efficient motion search algorithms for powerful frame interpolation are much needed at the decoder. In this paper, the RD performance of a Wyner-Ziv video codec is improved by using novel, advanced motion compensated frame interpolation techniques to generate the side information. The development of these type of side information estimators is a difficult problem in WZ video coding, especially because the decoder only has available some reference, decoded frames. Based on the regularization of the motion field, novel side information creation techniques are proposed in this paper along with a new frame interpolation framework able to generate higher quality side information at the decoder. To illustrate the RD performance improvements, this novel side information creation framework has been integrated in a transform domain turbo coding based Wyner-Ziv video codec. Experimental results show that the novel side information creation solution leads to better RD performance than available state-of-the-art side information estimators, with improvements up to 2 dB: moreover, it allows outperforming H.264/AVC Intra by up to 3 dB with a lower encoding complexity.

O processo ensino-aprendizagem: relatório de estágio

I - Inserido no Concelho de Odivelas, cuja realidade e contexto sócio cultural realçam a problemática da diversidade cultural, colocando ao professor dúvidas e dificuldades emrelação às suas práticas educativas, o Conservatório de Música D. Dinis é a escola na qual leciono desde 1993. É também local de reflexão permanente quanto aos critérios e condições que devem nortear a prática pedagógica contemporânea na área da música, cujo objetivo assenta na formação integral do aluno através da utilização de estratégias de ensino que o responsabilizem na própria aprendizagem. Considerando estes desafios, o seguinte trabalho será realizado no contexto da minha classe de violino e incidirá sobre três alunos em particular, que frequentam os seguintes graus, a saber: 1 - Iniciação (1º ciclo do ensino básico); 2 - 2º grau (2º ciclo do ensino básico); 3 - 5º grau (3º ciclo do ensino básico). Apesar de acreditar nas suas capacidades de aprendizagem e ter um cuidado especial sobre as minhas ações e os efeitos destas na aprendizagem académica e social dos meus alunos, os resultados finais são reveladores da importância da motivação, do apoio parental e da responsabilidade dos alunos na obtenção do seu próprio sucesso escolar.