We assessed the agreement between maximal oxygen consumption (VO2max) measured directly when performing the 20-m shuttle run test and estimated VO2max from five different equations (i.e., Barnett, equations a and b; Leger; Matsuzaka; and Ruiz) in youths. The 20-m shuttle run test was performed by 26 girls (mean age 14.6 years, s = 1.5; body mass 57.2 kg, s = 8.9; height 1.60 m, s = 0.06) and 22 boys (age 15.0 years, s = 1.6; body mass 63.5 kg, s = 11.5; height 1.70 m, s = 0.01). The participants wore a portable gas analyser (K4b2, Cosmed) to measure VO2max during the test. All the equations significantly underestimated directly measured VO2max, except Barnett's (b) equation. The mean difference ranged from 1.3 ml x kg(-1) x min(-1) (Barnett (b)) to 5.5 ml x kg(-1) x min(-1) (Leger). The standard error of the estimate ranged from 5.3 ml x kg(-1) x min(-1) (Ruiz) to 6.5 ml x kg(-1) x min(-1) (Leger), and the percentage error ranged from 21.2% (Ruiz) to 38.3% (Léger). The accuracy of the equations available to estimate VO2max from the 20-m shuttle run test is questionable at the individual level. Furthermore, special attention should be paid when comparisons are made between studies (e.g., population-based studies) using different equations. The results of the present study suggest that Barnett's (b) equation provides the closest agreement with directly measured VO2max (cardiorespiratory fitness) in youth.

This paper aims to present, dene and structure the car rental eet management problem, which includes operational eet management issues and problems traditionally studied under the revenue management framework. The car rental business has challenging and distinctive characteristics, which are mainly related with eet and decision-making exibility, and that render this problem relevant for academic research and practical applications. Three main contributions are presented: an in-depth literature review and discussion on car rental eet and revenue management issues, a novel integrating conceptual framework for this problem, and the identication of research directions for the future development of the eld.

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This paper is motivated by the problem of loading identical items of circular base (tubes, rolls, ...) into a rectangular base (the pallet). For practical reasons, all the loaded items are considered to have the same height. The resolution of this problem consists in determining the positioning pattern of the circular bases of the items on the rectangular pallet, while maximizing the number of items. This pattern will be repeated for each layer stacked on the pallet. Two algorithms based on the metaheuristic Simulated Annealing have been developed and implemented. The tuning of these algorithms parameters implied running intensive tests in order to improve its efficiency. The algorithms developed were easily extended to the case of non-identical circles.Keywords: cylinder packing, combinatorial optimization, simulated annealing. ResumoEste artigo aborda o problema de posicionamento de objetos de base circular (tubos, rolos, ...) sobre uma base retangular de maiores dimensões. Por razões práticas, considera-se que todos os objetos a carregar apresentam a mesma altura. A resolução do problema consiste na determinação do padrão de posicionamento das bases circulares dos referidos objetos sobre a base de forma retangular, tendo como objetivo a maximização do número de objetos estritamente posicionados no interior dessa base. Este padrão de posicionamento será repetido em cada uma das camadas a carregar sobre a base retangular. Apresentam-se dois algoritmos para a resolução do problema. Estes algoritmos baseiam-se numa metaheurística, Simulated Annealling, cuja afinação de parâmetros requereu a execução de testes intensivos com o objetivo de atingir um elevado grau de eficiência no seu desempenho. As características dos algoritmos implementados permitiram que a sua extensão à consideração de círculos com raios diferentes fosse facilmente conseguida.Palavras-chave: empacotamento de cilindros, otimização combinatória, simulated annealing.

In this work, we propose a novel approach to detect and track, in videoconference sequences, six landmarks on eyes: the four corners and the pupils. Detection is based on the Inner Product Detector (IPD), and tracking on the Lucas-Kanade (LK) technique. The novelty of our method consists in the integration between detection and tracking, the evaluation of the temporal consistency to decrease the false positive rates, and the use of geometrical constraints to infer the position of missing points. In our experiments, we use five high definition video sequences with four subjects, different types of background, fast movements, blurring and occlusion. The obtained results have shown that the proposed technique is capable of detecting and tracking landmarks with good reliability.

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