6 resultados para Empirical studies

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo


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This paper consists of a review of the literature about dividend policy in Brazil, focusing on the empirical studies conducted from 1990 to 2010 that were published in major Brazilian administration, accounting and finance journals and major conference proceedings on this subject. The analyzed sample comprised 39 studies using various methods and conducted in various periods. Based on the model of Harris and Raviv (1991), this paper grouped studies according to model type, and it found five main categories. We were able to find some tendencies, such as: dividend policy relevance in the Brazilian market; confirmation of existence of agency problems; conflicting findings regarding the clientele hypothesis; tax signaling in, and tax impact on, defining dividend policy; non-conflicting findings regarding key factors of dividend policy..

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Despite recognition of key biotic processes in shaping the structure of biological communities, few empirical studies have explored the influences of abiotic factors on the structural properties of mutualistic networks. We tested whether temperature and precipitation contribute to temporal variation in the nestedness of mutualistic ant-plant networks. While maintaining their nested structure, nestedness increased with mean monthly precipitation and, particularly, with monthly temperature. Moreover, some species changed their role in network structure, shifting from peripheral to core species within the nested network. We could summarize that abiotic factors affect plant species in the vegetation (e.g., phenology), meaning presence/absence of food sources, consequently an increase/decrease of associations with ants, and finally, these variations to fluctuations in nestedness. While biotic factors are certainly important, greater attention needs to be given to abiotic factors as underlying determinants of the structures of ecological networks.

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Theoretical and empirical studies demonstrate that the total amount of forest and the size and connectivity of fragments have nonlinear effects on species survival. We tested how habitat amount and configuration affect understory bird species richness and abundance. We used mist nets (almost 34,000 net hours) to sample birds in 53 Atlantic Forest fragments in southeastern Brazil. Fragments were distributed among 3 10,800-ha landscapes. The remaining forest in these landscapes was below (10% forest cover), similar to (30%), and above (50%) the theoretical fragmentation threshold (approximately 30%) below which the effects of fragmentation should be intensified. Species-richness estimates were significantly higher (F = 3715, p = 0.00) where 50% of the forest remained, which suggests a species occurrence threshold of 30-50% forest, which is higher than usually occurs (<30%). Relations between forest cover and species richness differed depending on species sensitivity to forest conversion and fragmentation. For less sensitive species, species richness decreased as forest cover increased, whereas for highly sensitive species the opposite occurred. For sensitive species, species richness and the amount of forest cover were positively related, particularly when forest cover was 30-50%. Fragment size and connectivity were related to species richness and abundance in all landscapes, not just below the 30% threshold. Where 10% of the forest remained, fragment size was more related to species richness and abundance than connectivity. However, the relation between connectivity and species richness and abundance was stronger where 30% of the landscape was forested. Where 50% of the landscape was forested, fragment size and connectivity were both related to species richness and abundance. Our results demonstrated a rapid loss of species at relatively high levels of forest cover (30-50%). Highly sensitive species were 3-4 times more common above the 30-50% threshold than below it; however, our results do not support a unique fragmentation threshold.

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BACKGROUND: Anxiety disorders are often associated with several non-psychiatric medical conditions. Among the clinical conditions found in association with anxiety stands out the joint hypermobility (JH). OBJECTIVES: To carry out a systematic review of the clinical association between anxiety disorders and JH. METHOD: A survey was conducted in MEDLINE, PsychINFO, LILACS e SciELO databases up to December 2011. We searched for articles using the keywords 'anxiety', 'joint' and 'hypermobility' and Boolean operators. The review included articles describing empirical studies on the association between JH and anxiety. The reference lists of selected articles were systematically hand-searched for other publications relevant to the review. RESULTS: Seventeen articles were included in the analysis and classified to better extract data. We found heterogeneity between the studies relate to the methodology used. Most of the studies found an association between anxiety features and JH. Panic disorder/agoraphobia was the anxiety disorder associated with JH in several studies. Etiological explanation of the relationship between anxiety and JH is still controversial. CONCLUSION: Future research in large samples from the community and clinical setting and longitudinal studies of the association between anxiety and HA and the underlying biological mechanisms involved in this association are welcome.

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Um dos papéis da contabilidade é prover informações sobre o desempenho empresarial, quer seja por indicadores contábil-financeiros ou não. Dentro deste escopo do interesse da contabilidade, observa-se que a publicação de estudos teórico-empíricos sobre as relações entre Performance Corporativa Financeira (CFP) e a Performance Social Corporativa (CSP) vem crescendo nos últimos anos, sintoma do desenvolvimento deste campo de pesquisa. Entretanto, a contribuição à teoria pelos trabalhos empíricos se faz de forma pontual, uma vez que normalmente cada estudo foca um aspecto particular da teoria. Periodicamente, portanto, é necessária uma análise que avalie como, de forma agregada, os estudos empíricos contribuíram para a evolução da teoria, e elaborar essa análise constituiu o objetivo do presente estudo. O referencial teórico abrangeu: teoria dos stakeholders, relação entre CSP e CFP, good management theory e slack resource theory. Esta pesquisa abrangeu um período de 15 anos (1996 a 2010) e a coleta de dados empregou a ferramenta de busca das bases de dados: Ebsco, Proquest e ISI. O processo de amostragem obteve um conjunto de 58 artigos exclusivamente teórico-empíricos quantitativos que testam a relação CSP-CFP. Os principais resultados no campo teórico demonstram um reforço da proposição de relação positiva entre CSP e CFP e da good management theory, uma deficiência na explicação na defasagem de tempo (lag) na relação de causalidade entre CSP e CFP, e deficiências na descrição do constructo de CSP. Isto sugere estudos futuros para investigar a defasagem de tempo na relação de causalidade entre CSP e CFP e as possíveis razões que levaram diversos estudos empíricos a não atestarem uma associação positiva entre CSP e CFP.

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Neonates hospitalized in a neonatal intensive care unit are exposed to many painful and stressful procedures. Biobehavioral pain reactivity in preterm infants during the neonatal period may reflect the capacity of the central nervous system to regulate arousal and neurobiological organization. We review empirical studies on the effects of sex, gestational age, and neonatal illness severity on pain reactivity in children born preterm. A literature search was conducted using PubMed, Institute of Scientific Information Web of Science, PsycINFO, Latin American and Caribbean Health Sciences Literature, and Scientific Electronic Library Online databases. Additionally, a special search was performed in online journals that publish pain studies including Pain, Early Human Development, European Journal of Pain, and Pain Management Nursing. The literature search covered the period from 2004 to 2009. Data were extracted according to predefined inclusion and exclusion criteria. Of the 18 studies reviewed, 16 analyzed gestational age, 13 examined neonatal illness severity, and eight focused on sex. Most of the studies analyzed more than one of these three variables. The majority of the studies found effects of gestational age (n = 14) and neonatal illness severity (n = 11) on pain responses. Only two studies found an influence of sex on infant pain responses. In conclusion, gestational age and neonatal illness severity influence pain responses in infants born preterm. Further studies should be conducted to examine the influence of sex on pain responses.