Costs and benefits of temporary brood desertion in a Neotropical harvestman (Arachnida: Opiliones)

Brood desertion is a life history strategy that allows parents to minimize costs related to parental care and increase their future fecundity. The harvestman Neosadocus maximus is an interesting model organism to study costs and benefits of temporary brood desertion because females abandon their clutches periodically and keep adding eggs to their clutches for some weeks. In this study, we tested if temporary brood desertion (a) imposes a cost to caring females by increasing the risk of egg predation and (b) offers a benefit to caring females by increasing fecundity as a result of increased foraging opportunities. With intensive field observations followed by a model selection approach, we showed that the proportion of consumed eggs was very low during the day and it was not influenced by the frequency of brood desertion. The proportion of consumed eggs was higher at night and it was negatively related to the frequency of brood desertion. However, frequent brood desertion did not result in higher fecundity, measured both as the number of eggs added to the current clutch and the probability of laying a second clutch over the course of the reproductive season. Considering that harvestmen are sensitive to dehydration, brood desertion during the day may attenuate the physiological stress of remaining exposed on the vegetation. Moreover, since brood desertion is higher during the day, when egg predation pressure is lower, caring females could be adjusting their maternal effort to the temporal variation in predation risk, which is regarded as the main cost of brood desertion in ectotherms.

Congruências entre posicionamentos estratégicos e redes de negócios: estudo de caso de uma subsidiária brasileira

Na pesquisa exploratória aqui relatada, realizada em 2009 e guiada por uma extensa revisão bibliográfica e pelo emprego do método de estudo de caso, busca-se identificar congruências entre o posicionamento estratégico adotado pela subsidiária brasileira de uma corporação multinacional e o tipo de rede de negócios por ela integrada. Apoiando-se em dois modelos específicos da literatura acadêmica sobre os temas mencionados (posicionamento estratégico e redes), as conclusões dessa investigação sugerem que as Redes Verticais de Demanda e Fornecimento (MOLLER e RAJALA, 2007) são adequadas para operacionalizar o posicionamento definido como Melhor Produto no Modelo Delta (HAX e WILDE II, 1999; 2001).

A palavra e as condições da educação escolar

Estudos recentes sobre gestão e resultados escolares apontam a presença do, assim chamado, efeito-professor como um fator associado ao desempenho dos alunos. Desenvolve-se neste texto a premissa de que esses estudos acabam, paradoxalmente, demonstrando a pertinência da reflexão psicanalítica, que aponta para o estatuto da palavra mestre no interior de uma tradição filial professoral como condição necessária à educação escolar.