3 research outputs found
A Poisson Mixed Model with Nonnormal Random Effect Distribution
We propose in this paper a random intercept Poisson model in which the random
effect distribution is assumed to follow a generalized log-gamma (GLG)
distribution. We derive the first two moments for the marginal distribution as
well as the intraclass correlation. Even though numerical integration methods
are in general required for deriving the marginal models, we obtain the
multivariate negative binomial model for a particular parameter setting of the
hierarchical model. An iterative process is derived for obtaining the maximum
likelihood estimates for the parameters in the multivariate negative binomial
model. Residual analysis are proposed and two applications with real data are
given for illustration.Comment: Submitted in the Computational Statistics & Data Analysis journa
Evaluation of lignans from piper cubeba against schistosoma mansoni adult worms: a combined experimental and theoretical study
Six dibenzylbutyrolactonic lignans ((-)-hinokinin (1), (-)-cubebin (2), (-)-yatein (3), (-)-5-methoxyyatein (4), dihydrocubebin (5) and dihydroclusin (6)) were isolated from Piper cubeba seed extract and evaluated against Schistosoma mansoni. All lignans, except 5, were able to separate the adult worm pairs and reduce the egg numbers during 24 h of incubation. Lignans 1, 3 and 4 (containing a lactone ring) were the most efficient concerning antiparasitary activity. Comparing structures 3 and 4, the presence of the methoxy group at position 5 appears to be important for this activity. Considering 1 and 3, it is possible to see that the substitution pattern change (methylenedioxy or methoxy groups) in positions 3 ' and 4 ' alter the biological response, with 1 being the second most active compound. Computational calculations suggest that the activity of compound 4 can be correlated with the largest lipophilicity value161CAPES - Coordenação de Aperfeiçoamento de Pessoal e NÃvel SuperiorCNPQ - Conselho Nacional de Desenvolvimento CientÃfico e TecnológicoFAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulo88881.068346/2014-01Sem informação009/15207-4; 2010/15332-0; 2011/07623-