ABSTRACT Aristotle introduces in Physics II 3 what has been commonly called his theory of the four causes. However, in recent decades it has become equally common the idea that what Aristotle does in fact in this, and other related passages, is to introduce a theory about the different types of explanations we could offer for phenomena in the natural world. In this article, I argue against such an interpretation of the Aristotelian notion of α’ιτία presenting two arguments to this effect. The first one develops an objection from the textual evidence that is often invoked in support of that view. The second and more important one shows the inadequacy of such a view in order to understand the relation that Aristotle envisages between chance and causation.

RESUMEN Aristóteles introduce en Física II 3 lo que comúnmente se ha considerado como su teoría de las cuatro causas. Sin embargo, en las décadas pasadas pareciera haberse vuelto igualmente común la idea de que lo que Aristóteles estaría haciendo en ese y otros pasajes paralelos es introducir una teoría sobre los distintos tipos de explicaciones que disponemos para dar cuenta de los fenómenos del mundo natural. El presente artículo argumenta en contra de tal interpretación de la noción aristotélica de α’ιτία. Para ello, presenta dos argumentos. Mientras el primero desarrolla una objeción de carácter textual contra tal postura interpretativa, el segundo - y más importante - mostraría la insuficiencia de esta postura para comprender adecuadamente la relación que Aristóteles entrevió entre la causalidad y el azar.

RESUMO Métodos simplificados são alternativas úteis para análise prévia dos efeitos da ruptura de barragens, podendo orientar a tomada de decisão da realização de estudos mais completos. Nesse contexto, propõe-se uma nova abordagem simplificada para análise de aspectos da ruptura de barragens de terra, cuja falha ocorre por galgamento, a partir da altura da barragem e do volume do reservatório como dados de entrada. Casos hipotéticos de ruptura foram analisados por meio de simulações hidrodinâmicas, cujos resultados permitiram desenvolver equações capazes de estimar o amortecimento da vazão de pico e o tempo de chegada da vazão máxima no vale a jusante. A abordagem proposta foi aplicada em estudo de caso hipotético (em uma barragem com 15 m de altura e 17 hm3 de volume no reservatório), obtendo-se resultados próximos dos alcançados por meio de outros metodos, especialmente na estimativa da vazão máxima no vale a jusante, onde as diferenças médias entre os resultados dos métodos considerados foram da ordem de 15%.

ABSTRACT Simplified methods are useful alternatives for prior analysis of the effects of dam rupture and can guide the decision-making process for carrying out more complete studies. In this context, a new simplified approach is presented, which enables the analysis of aspects from dam rupture of earthen dams that failed due to overtopping, considering dam height and reservoir volume as input data. Hypothetical cases were analyzed applying dam-break hydrodynamic simulations, which results allowed the development of equations capable of estimating peak flow attenuation and peak discharge arrival time along the downstream valley. The proposed approach was applied in a hypothetical case study (15 m high dam and 17 hm3 reservoir volume), obtaining results close to those achieved through other methods, especially in case of estimating the maximum discharges throughout the downstream valley, where the average differences between the results of the methods were of the order of 15%.

ABSTRACT This study evaluated the effects of feeding calcareous marine algae or sodium bicarbonate as rumen buffer on the performance, behaviour, in vitro diet digestibility, and meat quality of beef cattle. A total of 180 Charolaise bullocks (536±38 kg; 14±1 months of age) were divided into two homogeneous groups and fed a diet with a mineral mix containing 40% sodium bicarbonate or 20% calcareous marine algae (CMA) for the entire fattening period (130 days). Of the in vivo and in vitro parameters evaluated, CMA supplementation improved average daily gain and feed conversion ratio and reduced the prevalence of bloat and lameness. Bullocks fed CMA tended to exhibit a calmer behaviour while in the pen. Supplementation with CMA improved rumen pH and in vitro digestion. Meat from bullocks fed CMA showed a lower pH and higher lightness and tenderness. The results suggest that CMA is more effective than sodium bicarbonate in buffering beef cattle, with a positive impact on growth performance, feed efficiency, health, and meat quality.