Genetic heterogeneity of within-family variance of body weight in Atlantic salmon (Salmo salar)

BACKGROUND: Canalization is defined as the stability of a genotype against minor variations in both environment and genetics. Genetic variation in degree of canalization causes heterogeneity of within-family variance. The aims of this study are twofold: (1) quantify genetic heterogeneity of (within-family) residual variance in Atlantic salmon and (2) test whether the observed heterogeneity of (within-family) residual variance can be explained by simple scaling effects. RESULTS: Analysis of body weight in Atlantic salmon using a double hierarchical generalized linear model (DHGLM) revealed substantial heterogeneity of within-family variance. The 95% prediction interval for within-family variance ranged from ~0.4 to 1.2 kg2, implying that the within-family variance of the most extreme high families is expected to be approximately three times larger than the extreme low families. For cross-sectional data, DHGLM with an animal mean sub-model resulted in severe bias, while a corresponding sire-dam model was appropriate. Heterogeneity of variance was not sensitive to Box-Cox transformations of phenotypes, which implies that heterogeneity of variance exists beyond what would be expected from simple scaling effects. CONCLUSIONS: Substantial heterogeneity of within-family variance was found for body weight in Atlantic salmon. A tendency towards higher variance with higher means (scaling effects) was observed, but heterogeneity of within-family variance existed beyond what could be explained by simple scaling effects. For cross-sectional data, using the animal mean sub-model in the DHGLM resulted in biased estimates of variance components, which differed substantially both from a standard linear mean animal model and a sire-dam DHGLM model. Although genetic differences in canalization were observed, selection for increased canalization is difficult, because there is limited individual information for the variance sub-model, especially when based on cross-sectional data. Furthermore, potential macro-environmental changes (diet, climatic region, etc.) may make genetic heterogeneity of variance a less stable trait over time and space.

Hglm: A package for fitting hierarchical generalized linear models

We present the hglm package for fitting hierarchical generalized linear models. It can be used for linear mixed models and generalized linear mixed models with random effects for a variety of links and a variety of distributions for both the outcomes and the random effects. Fixed effects can also be fitted in the dispersion part of the model.

Likelihood prediction for generalized linear mixed models under covariate uncertainty

This paper presents the techniques of likelihood prediction for the generalized linear mixed models. Methods of likelihood prediction is explained through a series of examples; from a classical one to more complicated ones. The examples show, in simple cases, that the likelihood prediction (LP) coincides with already known best frequentist practice such as the best linear unbiased predictor. The paper outlines a way to deal with the covariate uncertainty while producing predictive inference. Using a Poisson error-in-variable generalized linear model, it has been shown that in complicated cases LP produces better results than already know methods.

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.

Humming as a mean of communicating during meal time situations : A Single Case study involving a women with severe dementia and her caregiver

Objective: ‘Music Therapeutic Caregiving’, when caregivers sing for or together with persons with dementia during morning care situations, has been shown to increase verbal and nonverbal communication between persons with dementia and their caregivers, as well as enhance positive and decrease negative emotions in persons with dementia. No studies about singing during mealtimes have been conducted, and this pilot project was designed to elucidate this. However, since previous studies have shown that there is a risk that persons with dementia will start to sing along with the caregiver, the caregiver in this study hummed such that the person with dementia did not sing instead of eat. The aim of this pilot project was threefold: to describe expressed emotions in a woman with severe dementia, and describe communication between her and her caregivers without and with the caregiver humming. The aim was also to measure food and liquid intake without and with humming. Method: The study was constructed as a Single Case ABA design in which the ordinary mealtime constituted a baseline which comprised a woman with severe dementia being fed by her caregivers in the usual way. The intervention included the same woman being fed by the same caregiver who hummed while feeding her. Data comprised video observations that were collected once per week over 5 consecutive weeks. The Verbal and Nonverbal Interaction Scale and Observed Emotion Rating Scale were used to analyze the recorded interactions. Results: A slightly positive influence of communication was shown for the woman with dementia, as well as for the caregiver. Further, the women with dementia showed a slight increase in expressions of positive emotions, and she ate more during the intervention. Conclusion: Based on this pilot study no general conclusions can be drawn. It can be concluded, however, that humming while feeding persons with dementia might slightly enhance communication, and positive expressed emotions in persons with dementia. To confirm this, more studies on group levels are needed. Because previous studies have found that caregiver singing during caring situations influences persons with dementia positively it might be desirable to test the same during mealtime.

Just which Reality do you Mean? Users' Experiences of Virtual Spaces

Virtual Reality is a relatively new technology in the relatively young field of computer science. The design of Virtual Reality has only recently come into discussion, as well as the implications for this sort of design. I hope to determine how a user can work most efficiently and accurately in a Virtual World. By studying this, I hope to help in the standardization of Virtual Reality design.

Seguimento clinoceletrográfico de criançcas e adolescentes com crise epiléptica única não-provocada

Os fenômenos convulsivos despertaram o interesse de estudiosos e pensadores já na Antigüidade, quando aspectos mágicos e sobrenaturais eram a eles associados. No século XIX foram lançadas as bases dos conceitos atuais sobre a desestruturação funcional cerebral na epilepsia, e Berger, em 1929, marcou definitivamente a história com a descoberta dos ritmos cerebrais. Crise epiléptica e epilepsia não são sinônimos, já que o último termo refere-se a crises recorrentes espontâneas. Ela costuma iniciar na infância, daí a preocupação com o risco de repetição do primeiro episódio e com a decisão de instituir tratamento medicamentoso. Fatores prognósticos são apontados, mas não há consenso. No Brasil existem poucas pesquisas nesta linha, tanto de prevalência da epilepsia como de fatores envolvidos na recorrência de crises. Este estudo teve como objetivo geral avaliar aspectos clinicoeletrográficos capazes de auxiliar no prognóstico e no manejo da epilepsia da criança e do adolescente. Foram objetivos específicos determinar a incidência de crise epiléptica não provocada recorrente; identificar fatores remotos implicados na ocorrência de crise epiléptica; relacionar tipo de crise com achados eletrencefalográficos; relacionar tipo de crise, duração da crise, estado vigília/sono no momento da crise e achados eletrencefalográficos com possibilidade de recorrência; e identificar os fatores de risco para epilepsia. Foram acompanhados 109 pacientes com idades entre 1 mês e 16 anos, com primeira crise não-provocada, em média por 24 meses, a intervalos trimestrais, no Hospital de Clínicas de Porto Alegre (HCPA). Foram realizados eletrencefalogramas (EEG) após a primeira crise; depois, solicitados anualmente. Não foram incluídos casos com epilepsia ou síndrome epiléptica bem definida, ou que fizeram uso prévio de drogas antiepilépticas. A média de idade foi 6 anos, com predomínio da faixa etária de 6 a 12 anos. Setenta eram meninos e 39, meninas. Os indivíduos brancos eram 92, e os não-brancos, 17. O nível de escolaridade dos casos esteve de acordo com a distribuição da idade e, entre os responsáveis, predominaram 8 anos de escolaridade. Foi possível concluir que as crises únicas não-provocadas mais freqüentes foram generalizadas, e sem predomínio significativo do tipo de EEG. A incidência de crise não-provocada recorrente foi 51,4%. História de intercorrências pré-natais maternas aumentou em 2 vezes o risco de repetição de crises. Via de nascimento, escore de Apgar no 5º minuto, relação peso ao nascer/idade gestacional, intercorrências no período pós-natal imediato e desenvolvimento neuropsicomotor não tiveram influência na recorrência. História familiar de crises mostrou tendência à significância estatística para repetição dos episódios, com risco de 1,7. Não foi encontrada associação entre tipo de crise e achado eletrencefalográfico. A maioria das crises foi de curta duração (até 5 minutos), mas este dado não esteve relacionado com a recorrência. Estado de vigília teve efeito protetor na recorrência. Se a primeira crise foi parcial, o risco de repetição foi 1,62, com tendência à significância. Quando o primeiro EEG foi alterado, houve relação significativa com primeira crise tanto generalizada como parcial. O primeiro EEG com alterações paroxísticas focais apontou risco de repetição de 2,90. Quando as variáveis envolvidas na repetição de crises foram ajustadas pelo modelo de regressão de Cox, EEG alterado mostrou risco de 2,48, com riscos acumulados de 50%, 60%, 62% e 68%; com EEG normal, os riscos foram 26%, 32%, 34% e 36% em 6, 12, 18 e 24 meses respectivamente.

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.

Revisão sistemática e meta-análise do uso de antidepressivos no transtorno de ansiedade generalizada

Revisão da Literatura: O Transtorno de Ansiedade Generalizada (TAG) é caracterizado por preocupação excessiva, persistente e incontrolável sobre diversos aspectos da vida do paciente. Tem prevalência entre 1,6% e 5,1% e índice de comorbidades de até 90,4%. As principais comorbidades são depressão maior (64%) e distimia (37%). Os antidepressivos podem ser eficazes no tratamento do TAG. A Medicina Baseada em Evidências (MBE) busca reunir a melhor evidência disponível com experiência clínica e conhecimentos de fisiopatologia. A melhor maneira disponível de síntese das evidências é a revisão sistemática e a meta-análise. Objetivos: Investigar a eficácia e tolerabilidade dos antidepressivos no tratamento do TAG através de uma revisão sistemática da literatura e meta-análise. Sumário do artigo científico: A revisão sistemática incluiu ensaios clínicos randomizados e controlados e excluiu estudos não-randomizados, estudos com pacientes com TAG e outro transtorno de eixo I. Os dados foram extraídos por dois revisores independentes e risco relativo, diferença da média ponderada e número necessário para tratamento (NNT) foram calculados. Antidepressivos (imipramina, paroxetina e venlafaxina) foram superiores ao placebo. O NNT calculado foi de 5,5. A evidência disponível sugere que os antidepressivos são superiores ao placebo no tratamento do TAG e bem tolerados pelos pacientes.

Essays on Spatial Econometrics

Esta dissertação concentra-se nos processos estocásticos espaciais definidos em um reticulado, os chamados modelos do tipo Cliff & Ord. Minha contribuição nesta tese consiste em utilizar aproximações de Edgeworth e saddlepoint para investigar as propriedades em amostras finitas do teste para detectar a presença de dependência espacial em modelos SAR (autoregressivo espacial), e propor uma nova classe de modelos econométricos espaciais na qual os parâmetros que afetam a estrutura da média são distintos dos parâmetros presentes na estrutura da variância do processo. Isto permite uma interpretação mais clara dos parâmetros do modelo, além de generalizar uma proposta de taxonomia feita por Anselin (2003). Eu proponho um estimador para os parâmetros do modelo e derivo a distribuição assintótica do estimador. O modelo sugerido na dissertação fornece uma interpretação interessante ao modelo SARAR, bastante comum na literatura. A investigação das propriedades em amostras finitas dos testes expande com relação a literatura permitindo que a matriz de vizinhança do processo espacial seja uma função não-linear do parâmetro de dependência espacial. A utilização de aproximações ao invés de simulações (mais comum na literatura), permite uma maneira fácil de comparar as propriedades dos testes com diferentes matrizes de vizinhança e corrigir o tamanho ao comparar a potência dos testes. Eu obtenho teste invariante ótimo que é também localmente uniformemente mais potente (LUMPI). Construo o envelope de potência para o teste LUMPI e mostro que ele é virtualmente UMP, pois a potência do teste está muito próxima ao envelope (considerando as estruturas espaciais definidas na dissertação). Eu sugiro um procedimento prático para construir um teste que tem boa potência em uma gama de situações onde talvez o teste LUMPI não tenha boas propriedades. Eu concluo que a potência do teste aumenta com o tamanho da amostra e com o parâmetro de dependência espacial (o que está de acordo com a literatura). Entretanto, disputo a visão consensual que a potência do teste diminui a medida que a matriz de vizinhança fica mais densa. Isto reflete um erro de medida comum na literatura, pois a distância estatística entre a hipótese nula e a alternativa varia muito com a estrutura da matriz. Fazendo a correção, concluo que a potência do teste aumenta com a distância da alternativa à nula, como esperado.

Iguatemi: creating opportunities for international luxury brands in Brazil

The Brazilian luxury goods market has been registering substantial growth with many international brands establishing presence in the country. When entering the market, the perfect location seems for most of them to be found in Iguatemi Group’s Shopping Malls. This research focuses the topic of Luxury Market and Retail, in the form of a case study on Iguatemi Group, which tries to understand How is Iguatemi Group creating opportunities for International Luxury Brands in Brazil? To understand the context of the case, the text explores the Brazilian market evolution, its attraction factors and challenges, the location choice methodology used by international luxury brands, and finally, how is the Iguatemi Group creating opportunities for these brands in Brazil. For doing so, a multiple-methods approach was followed so to achieve a non-biased result. In-depth interviews were conducted with Iguatemi’s managers, international luxury brands’ managers and experts in luxury market and retail; non-participant observation was held, and documentation was examined. The research found that the entry of International Luxury Brands in Brazil started about 20 years ago, mainly explained by the positive structural economic reforms Brazil experienced in this period. 60% of the studied brands chose São Paulo’s Iguatemi malls as first location, in particular Iguatemi São Paulo and JK Iguatemi. The preference over these locations relies mainly on the reputation of the Iguatemi brand and on its positioning in the market which seems to be aligned to that of these brands. From its side, Iguatemi has started actively gathering international luxury brands into the market since 15 years ago, and has intensified its action by creating iRetail, an internal company to the group representing some international luxury brands in Brazil, which have, thus, exclusive locations in its malls. The role of Iguatemi, hence, goes beyond that of a real estate company, by approaching the market with a 360° strategy. These findings contribute for academic purposes, in the extent to which they propose a so far rather unexplored topic, and for managerial purposes by describing a best practice in the shopping center sector. However, the study does not mean to be generalized. Consumers’ perspectives on Iguatemi Group were not addressed; rather, the research took a business to business approach.

Microfounded forecasting

Our focus is on information in expectation surveys that can now be built on thousands (or millions) of respondents on an almost continuous-time basis (big data) and in continuous macroeconomic surveys with a limited number of respondents. We show that, under standard microeconomic and econometric techniques, survey forecasts are an affine function of the conditional expectation of the target variable. This is true whether or not the survey respondent knows the data-generating process (DGP) of the target variable or the econometrician knows the respondents individual loss function. If the econometrician has a mean-squared-error risk function, we show that asymptotically efficient forecasts of the target variable can be built using Hansens (Econometrica, 1982) generalized method of moments in a panel-data context, when N and T diverge or when T diverges with N xed. Sequential asymptotic results are obtained using Phillips and Moon s (Econometrica, 1999) framework. Possible extensions are also discussed.