Fitting conditional and simultaneous autoregressive spatial models in hglm

We present a new version (> 2.0) of the hglm package for fitting hierarchical generalized linear models (HGLMs) with spatially correlated random effects. CAR() and SAR() families for conditional and simultaneous autoregressive random effects were implemented. Eigen decomposition of the matrix describing the spatial structure (e.g., the neighborhood matrix) was used to transform the CAR/SAR random effects into an independent, but eteroscedastic, Gaussian random effect. A linear predictor is fitted for the random effect variance to estimate the parameters in the CAR and SAR models. This gives a computationally efficient algorithm for moderately sized problems.

Parameter estimation of Poisson generalized linear mixed models based on three different statistical principles : a simulation study

Generalized linear mixed models are flexible tools for modeling non-normal data and are useful for accommodating overdispersion in Poisson regression models with random effects. Their main difficulty resides in the parameter estimation because there is no analytic solution for the maximization of the marginal likelihood. Many methods have been proposed for this purpose and many of them are implemented in software packages. The purpose of this study is to compare the performance of three different statistical principles - marginal likelihood, extended likelihood, Bayesian analysis-via simulation studies. Real data on contact wrestling are used for illustration.

Forecasting electricity demand using generalized long memory

This paper studies the electricity hourly load demand in the area covered by a utility situated in the southeast of Brazil. We propose a stochastic model which employs generalized long memory (by means of Gegenbauer processes) to model the seasonal behavior of the load. The model is proposed for sectional data, that is, each hour’s load is studied separately as a single series. This approach avoids modeling the intricate intra-day pattern (load profile) displayed by the load, which varies throughout days of the week and seasons. The forecasting performance of the model is compared with a SARIMA benchmark using the years of 1999 and 2000 as the out-of-sample. The model clearly outperforms the benchmark. We conclude for general long memory in the series.

Solução da equação de difusão-advecção para uma CLP não-homogênea e não-estacionária pelo método GILTT

Neste trabalho é apresentada a solução da equação de difusão-advecção transiente para simular a dispersão de poluentes na Camada Limite Planetária. A solução é obtida através do método analítico GILTT (Generalized Integral Laplace Transform Technique) e da técnica de inversão numérica da quadratura de Gauss. A validação da solução é comprovada utilizando as concentraçãos obtidas a partir do modelo com as obtidas experimentalmente pelo Experimento de Copenhagen. Nesta comparação foram utilizados os perfis de vento potencial e logaritmo e os parâmetros de turbulência propostos por Degrazia et al (1997) [19] e (2002) [17]. Os melhores resultados foram obtidos utilizando o perfil de vento potencial e o coeficiente de difusão propostos por Degrazia et al (1997). A influência da velocidade vertical é mostrada através do comportamento das concentrações de poluentes na pluma. Além disso, as velocidades verticais e longitudinais geradas pelo Large Eddy Simulation (LES) foram colocadas no modelo para poder simular uma camada limite turbulenta mais realística, a qual apresentou resultados satisfatórios quando comparados com os disponíveis na literatura.

Evolução de camada limite planetária para dispersão de poluentes pelo método da GILTT

O objetivo deste trabalho é obter os parâmetros turbulentos para o crescimento da camada limite planetária (CLP), durante a realizaçãoo do experimento Olad (Overland along wind dispersion experiment), conduzido na transição da noite para o dia. Nesta hora a CLP exibe uma altura, geralmente, pequena, disponibilizando pouco volume para a dispersão dos poluentes. Assim, concentrações superficiais elevadas podem ocorrer, atacando materiais, plantas e a saúde da população. Logo, conhecer os parâmetros do crescimneto é de fundamental importância para o correto modelamento da dispersão atmosférica ao amanhecer. A validação dos parâmetros é realizada a partir da solução da equação da difusão-advecção bidimensional, pelo método da GILTT (Generalized Integral Laplace Transform Technique). São empregados coeficientes de difusão turbulenta (problema de fechamento) dependentes da estabilidade atmosférica. As concentrações superficiais tridimensionais são obtidas através do espalhamento lateral da pluma com distribuição gaussiana. Apresentam-se os resultados numéricos e estatísticos, comparando os resultados obtidos com os dados experimentais. O modelo proposto mostrou-se aceitável em relação aos dados do experimento.

The not so generalized effects of nonreciprocal trade agreements

This dissertation uses an empirical gravity equation approach to study the relationship between nonreciprocal trade agreements (NRTAs) and members’ trade flows. Estimations relate bilateral imports to trade policy variables using a very comprehensive dataset with over fifty years of data. Results show that meager average trade effects exist only if members are excluded from the world trading system or if they are very poor. As trade flows between NRTA members are already rising before their creation, results also suggest a strong endogeneity concerning their formation. Moreover, estimations show that uncertainty and discretion tend to critically hinder NRTA’s performance. On the other hand, reciprocal trade agreements show the opposite pattern regardless of members’ income status.Encouraging developing countries’ openness to trade through reciprocal liberalization emerges consequently as a possible policy implication.

Generalized systemic cryptococcosis in a dog after immunosuppressive corticotherapy

Um cão da raça Boxer, macho, com 2 anos e 11 meses de idade foi encaminhado ao hospital veterinário com histórico de distúrbio gastroentérico de dois meses de duração, apatia, hiporexia, emagrecimento progressivo e deficiência visual. Ataxia e vocalização foram observadas posteriormente. O animal estava sendo tratado em outra clínica veterinária com antibióticos e doses imunossupressoras de corticóides, direcionados ao controle de provável enterite alimentar. A morte ocorreu após cinco dias. As observações macro e microscópica revelaram tratar-se de criptococose sistêmica, atingindo trato digestório, olhos, SNC, rins, pâncreas e linfonodos. O presente relato enfatiza a infecção fúngica criptocócica quanto aos seus aspectos grastrointestinais iniciais a serem considerados no diagnóstico clínico, ressaltando a imunossupressão induzida pela corticoterapia.

A Formação docente no fazer e refazer da prática pedagógica

This work dealt with formative actions that were developed by Educational Practice in Movement (GEPEM) at Universidade Federal do Rio Grande do Norte (UFRN). This group aims to transform the way education is carried out. This is done either through intervention or in research considering that school has an explicit objective, to change action, and this presupposes an educator formation process. The methodology used is a reflection on educational practice, aiming to built knowledge that can be generalized to other realities. The analysis of the group s prior work was done considering what has been used as a parameter for decision making, the regularity in the process itself, all of which allowed the identification of their principles, once these were always mentioned in the documents that were analyzed. Some principles for formative actions of the GEPEM were identified: the subject as a social historical being is part of a given community; knowledge is built through social relations and local reality is a content generator; dialogically, collective construction and awareness process. The research also pointed out four characterized organizers, parameters and action criteria that make articulation with practice possible. Thus, these are used in order to analyze two initial formation proposals (secondary and higher education) of rural settlement educators

Generalized linear mixed models for the genetic evaluation of binary reproductive traits: a simulation study

The objective of this study was to evaluate the use of probit and logit link functions for the genetic evaluation of early pregnancy using simulated data. The following simulation/analysis structures were constructed: logit/logit, logit/probit, probit/logit, and probit/probit. The percentages of precocious females were 5, 10, 15, 20, 25 and 30% and were adjusted based on a change in the mean of the latent variable. The parametric heritability (h²) was 0.40. Simulation and genetic evaluation were implemented in the R software. Heritability estimates (ĥ²) were compared with h² using the mean squared error. Pearson correlations between predicted and true breeding values and the percentage of coincidence between true and predicted ranking, considering the 10% of bulls with the highest breeding values (TOP10) were calculated. The mean ĥ² values were under- and overestimated for all percentages of precocious females when logit/probit and probit/logit models used. In addition, the mean squared errors of these models were high when compared with those obtained with the probit/probit and logit/logit models. Considering ĥ², probit/probit and logit/logit were also superior to logit/probit and probit/logit, providing values close to the parametric heritability. Logit/probit and probit/logit presented low Pearson correlations, whereas the correlations obtained with probit/probit and logit/logit ranged from moderate to high. With respect to the TOP10 bulls, logit/probit and probit/logit presented much lower percentages than probit/probit and logit/logit. The genetic parameter estimates and predictions of breeding values of the animals obtained with the logit/logit and probit/probit models were similar. In contrast, the results obtained with probit/logit and logit/probit were not satisfactory. There is need to compare the estimation and prediction ability of logit and probit link functions.

The dorsal raphe nucleus exerts opposed control on generalized anxiety and panic-related defensive responses in rats

It has been proposed that the ascending dorsal raphe (DR)-serotonergic (5-HT) pathway facilitates conditioned avoidance responses to potential or distal threat, while the DR-periventricular 5-HT pathway inhibits unconditioned flight reactions to proximal danger. Dysfunction on these pathways would be, respectively, related to generalized anxiety (GAD) and panic disorder (PD). To investigate this hypothesis, we microinjected into the rat DR the benzodiazepine inverse receptor agonist FG 7142, the 5-HT1A receptor agonist 8-OH-DPAT or the GABA(A) receptor agonist muscimol. Animals were evaluated in the elevated T-maze (ETM) and light/dark transition test. These models generate defensive responses that have been related to GAD and PD. Experiments were also conducted in the ETM 14 days after the selective lesion of DR serotonergic neurons by 5,7-dihydroxytriptamine (DHT). In all cases, rats were pre-exposed to one of the open arms of the ETM 1 day before testing. The results showed that FG 7142 facilitated inhibitory avoidance, an anxiogenic effect, while impairing one-way escape, an anxiolytic effect. 8-OH-DPAT, muscimol, and 5,7-DHT-induced lesions acted in the opposite direction, impairing inhibitory avoidance while facilitating one-way escape from the open arm. In the light/dark transition, 8-OH-DPAT and muscimol increased the time spent in the lighted compartment, an anxiolytic effect. The data supports the view that distinct DR-5-HT pathways regulate neural mechanisms underlying GAD and PD. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Involvement of median raphe nucleus 5-HT1A receptors in the regulation of generalized anxiety-related defensive behaviours in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

IFTrace: Video segmentation of deformable objects using the Image Foresting Transform

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)