Type checking by domain analysis in Ampersand

In the process of incorporating subtyping in relation algebra, an algorithm was found to derive the subtyping relation from the program to be checked. By using domain analysis rather than type inference, this algorithm offers an attractive visualization of the type derivation process. This visualization can be used as a graphical proof that the type system has assigned types correctly. An implementation is linked to in this paper, written in Haskell. The algorithm has been tried and tested in Ampersand, a language that uses relation algebra for the purpose of designing information systems

Feeding rates for bullfrogs with automated feed management and high feeding frequency

Three feeding rates (3, 4 and 5% of body weight/day - BW/day) with automated feed management and high feeding frequency (24 meals/day) for bullfrogs (Lithobates catesbeianus) under wet systems were evaluated in this 60-day experiment. Bullfrogs with an average weight of 31.91±0.97 g, were distributed into twelve 20 m2 wet pens at a density of 60 frogs/m2. Commercial extruded feed for carnivorous fish was supplied directly onto water surface by automatic feeders. At 20 and 40 days of the experiment, the best growth was observed in frogs treated with a feeding rate of 5% BW/day. The frogs reached an average weight of 100.2 g at the end of the experiment but there was no difference among the feeding rates. At the end of the experiment, feeding rates of 3, 4 and 5% BW/day resulted in apparent feed conversion values of 1.08, 1.56 and 1.52, respectively, which are considered excellent for frog rearing. Bullfrogs reared at ideal temperature and with an average weight of 31.9 to 87.6 g can be fed at a high feeding rate (5% BW/day) for a greater growth. When temperature is lower than 25°C, feeding rate of 3% BW/day could be considered the most suitable for bullfrog weighing from 87.6 to 100.2 g, because the feed conversion ratio was numerically better and reduced feed leftovers.Três taxas de alimentação (3, 4 e 5% do peso vivo/dia – PV/dia) com manejo alimentar automatizado e alta frequência alimentar (24 refeições/dia) para rã-touro (Lithobates catesbeianus) em sistema inundado foram avaliadas em 60 dias de experimento. Rãs-touro, com peso médio de 31,91±0,97 g, foram distribuídas em 12 baias inundadas de 20 m2 com densidade de 60 rãs/m2. Ração comercial extrusada para peixes carnívoros foi fornecida diretamente sobre a superfície da água por meio de alimentadores automáticos. O melhor crescimento das rãs, aos 20 e 40 dias de experimento, foi observado com as rãs alimentadas com taxa alimentar de 5% PV/dia, e ao final do experimento as rãs atingiram peso médio de 100,2 g, entretanto não houve diferença entre as taxas de alimentação. As taxas alimentares de 3, 4 e 5% PV/dia proporcionaram ao final do experimento conversão alimentar aparente de 1.08, 1.56 e 1.52, respectivamente, considerados excelente na criação de rãs. Rãs-touro criadas em temperatura ideal, com peso médio de 31,9 a 87,6 g, podem ser alimentadas com alta taxa alimentar (5% PV/dia) para maior crescimento. Quando a temperatura é menor que 25°C, a taxa alimentar de 3% PV/dia pode ser considerada mais adequada para rãs-touro pesando 87,6 a 100,2 g, pois apresentou taxa de conversão alimentar numericamente melhor, diminuindo os desperdícios de ração

Raising bullfrogs (Rana catesbeiana) in cages placed in tilapia ponds.

Brazilian systems for raising bullfrogs (concrete enclosure, concrete enclosure with feed dispenser and shelter, flooded enclosure) do not use enough water to keep temperature stable, and the low rate of water renewal hinders water quality. In this article we propose raising frogs in cages placed in fish ponds having high thermal stability. The experiment consisted in evaluating the productive performance of bullfrogs housed in 1 m3 cages at the densities of 28, 56 or 84 animals/cage, fed a ration delivered by an automatic dispenser. Each pond was 72 m2 large. Two fish densities were used (200 or 300 tilapias/pond). The experimental period lasted 105 days for tilapias (May-August) and 60 days for frogs (July-August). No significant differences among densities were observed for frog performance. Using 200 tilapias/pond improved fish weight gain and dissolved oxygen concentration, as compared to 300 tilapias/pond. This new rearing system provided an adequate environment for frogs, as there was weight gain and zero mortality during winter.No Brasil, os sistemas de criação de rãs (confinamento, anfigranja, inundado) utilizam um volume de água insuficiente para a manutenção da estabilidade térmica, e a baixa renovação prejudica a qualidade da água. Neste trabalho foi proposto a criação de rãs em tanques-rede distribuídos em viveiros com grande estabilidade térmica. O experimento consistiu em avaliar o desempenho produtivo de rãs-touro alojadas em tanques-rede de 1 m3, nas densidades de: 28, 56 e 84 animais por tanque-rede, alimentadas com ração fornecida por dispensador automático. Nos viveiros de 72 m2 utilizaram-se duas densidades de tilápias (200 e 300 peixes por viveiro). O período experimental foi de 105 dias para as tilápias (maio a agosto) e de 60 dias para as rãs (julho e agosto). Não foram observadas diferenças significativas no desem-penho das rãs para as diferentes densidades. A utilização de 200 tilápias por viveiro melhorou o ganho de peso dos peixes e a concentração de oxigênio dissolvido da água, comparado com a densidade de 300 peixes por viveiro. Este novo sistema de criação proporcionou um ambiente adequado para as rãs com ganho de peso e ausência de mortalidade durante o inverno

Automatic feeders for Nile tilapia raised in cages: productive performance at high feeding frequencies and different rates

ABSTRACT The main goal of modern intensive fish farms should be to increase productivity at a low cost. The automation of fish feeding plays an important role in this scenario since it may improve feed efficiency and reduce organic waste emissions. The aim of this experiment was to provide basic information for the development of feeding techniques using automatic feeders. The experiment was done from September to December, with tilapia weighing 185g, fed 48 meals a day at 22 or 30 minute intervals, with feeding rates of 2, 3 and 4% of live weight. Eighteen 1m3 net cages equipped with automatic feeders were distributed in one pond. During the experimental trial the mean values for dissolved oxygen, pH and temperature were 3.20mg/l, 8.03 and 25.43°C, respectively. The highest average weight of 683.73g was achieved for fish treated with 4% of live weight at 30 minute intervals between meals. There was no difference for viscero-somatic index, demonstrating no alteration in the final carcass quality. These results demonstrate that a higher feeding rate added to efficient feed management can be used at the final stages of raising Nile tilapia in cages without compromising final fish productive quality