De acordo com o trabalho de Brady (2008), mudanças estruturais na economia norte-americana que permitiram um aumento do crédito ao consumidor teriam tornado a suavização do consumo uma realidade. No entanto, ele estima um modelo de consumo levando em conta quebras estruturais encontradas nas séries do crescimento das variáveis, o que não implica, necessariamente, que essas quebras também estão presentes no modelo de consumo. Neste trabalho, utilizamos uma metodologia que permite a presença de regressores endógenos na equação de teste e procuramos as quebras diretamente no modelo de consumo. Os resultados indicam que o procedimento adotado por Brady (2008) não e adequado para determinar as datas das quebras do modelo de consumo. / According to Brady (2008), structural changes in the American economy that allowed an expansion of the consumer credit would have made consumption smoothing a reality. However, he estimates a model of consumption based on structural breaks found in the consumption and credit growth rates, which doesn\'t imply, necessarily, that those breaks are also present in the consumption\'s model. In this work, we use a methodology that is able to _nd multiple breaks when the regressors are endogenous and search the breaks directly in the consumption\'s model. Our results indicate that imposing the breaks as Brady (2008) did is not adequate to determine the break dates in the consumption\'s model.

De acordo com o trabalho de Brady (2008), mudanças estruturais na economia norte-americana que permitiram um aumento do crédito ao consumidor teriam tornado a suavização do consumo uma realidade. No entanto, ele estima um modelo de consumo levando em conta quebras estruturais encontradas nas séries do crescimento das variáveis, o que não implica, necessariamente, que essas quebras também estão presentes no modelo de consumo. Neste trabalho, utilizamos uma metodologia que permite a presença de regressores endógenos na equação de teste e procuramos as quebras diretamente no modelo de consumo. Os resultados indicam que o procedimento adotado por Brady (2008) não e adequado para determinar as datas das quebras do modelo de consumo. / According to Brady (2008), structural changes in the American economy that allowed an expansion of the consumer credit would have made consumption smoothing a reality. However, he estimates a model of consumption based on structural breaks found in the consumption and credit growth rates, which doesn\'t imply, necessarily, that those breaks are also present in the consumption\'s model. In this work, we use a methodology that is able to _nd multiple breaks when the regressors are endogenous and search the breaks directly in the consumption\'s model. Our results indicate that imposing the breaks as Brady (2008) did is not adequate to determine the break dates in the consumption\'s model.

This study focuses on relationships between individual condition, measures of ornament expression and mate choice in the Grey Partridge (Perdix perdix). It is based on the correlative data as well as results of manipulative experiments. I found positive correlation between the size of melanin- and carotenoid-based ornaments in partridges. The size and the redness of the carotenoid skin patch, and the size of the melanin-based feather ornamentation were associated with several measures of immunity and overall body condition (complement activity, ratio of immature erythrocytes, heterophil/leucocyte ratio, response to novel antigen). Furthermore, data from natural populations indicate that the expression of carotenoid-based ornamentation is associated with sexual attractiveness (measured as the ability to obtain a social mate) in partridges. Data from captive individuals indicate that carotenoid supplementation improves the redness of carotenoid-based ornament, while the stimulation of the immune system under increasing concentrations of supplemented carotenoids has no measurable effect on condition and physiological state. This seems to contradict predictions of the 'Carotenoid maintenance hypothesis'. Overall, results better understanding the role of carotenoid and melanin-based ornamentation in signaling...