Improved estimators for dispersion models with dispersion covariates

In this paper we discuss improved estimators for the regression and the dispersion parameters in an extended class of dispersion models (J{\o}rgensen, 1996). This class extends the regular dispersion models by letting the dispersion parameter vary throughout the observations, and contains the dispersion models as particular case. General formulae for the second-order bias are obtained explicitly in dispersion models with dispersion covariates, which generalize previous results by Botter and Cordeiro (1998), Cordeiro and McCullagh (1991), Cordeiro and Vasconcellos (1999), and Paula (1992). The practical use of the formulae is that we can derive closed-form expressions for the second-order biases of the maximum likelihood estimators of the regression and dispersion parameters when the information matrix has a closed-form. Various expressions for the second-order biases are given for special models. The formulae have advantages for numerical purposes because they require only a supplementary weighted linear regression. We also compare these bias-corrected estimators with two different estimators which are also bias-free to the second-order that are based on bootstrap methods. These estimators are compared by simulation

Is a Genome a Codeword of an Error-Correcting Code?

Since a genome is a discrete sequence, the elements of which belong to a set of four letters, the question as to whether or not there is an error-correcting code underlying DNA sequences is unavoidable. The most common approach to answering this question is to propose a methodology to verify the existence of such a code. However, none of the methodologies proposed so far, although quite clever, has achieved that goal. In a recent work, we showed that DNA sequences can be identified as codewords in a class of cyclic error-correcting codes known as Hamming codes. In this paper, we show that a complete intron-exon gene, and even a plasmid genome, can be identified as a Hamming code codeword as well. Although this does not constitute a definitive proof that there is an error-correcting code underlying DNA sequences, it is the first evidence in this direction

Free access to medicines for the treatment of chronic diseases in Brazil

ABSTRACT OBJECTIVE: To analyze the free access to medicines for the treatment of chronic diseases in the Brazilian population, according to demographic and socioeconomic factors. We also analyzed the most used pharmacological groups, according to funding source: free-of-charge or out-of-pocket paid. METHODS: Analysis of data from the Pesquisa Nacional sobre Acesso, Utilização e Promoção do Uso Racional de Medicamentos (PNAUM -National Survey on Access, Use and Promotion of Rational Use of Medicines), a population-based household survey, of cross-sectional design, based on probabilistic sample of the Brazilian population. We analyzed as outcome the prevalence of free access ( free-of-charge) to all medicines for treatment of the reported chronic diseases, in the last 30 days. We studied the following independent variables: sex, age group, education in complete years of school, economic class, health plan, and geographical region of residence. We estimated the prevalences and 95% confidence intervals (95%CI) and applied the Pearson's Chi-squared test to assess the differences between the groups, considering a 5% significance level. RESULTS: About half of adults and older adults who have had full access to the treatment of chronic diseases in Brazil obtained all needed medicines for free (47.5%; 95%CI 45.1-50.0). The prevalences of free access were higher among men (51.4%; 95%CI 48.1-54.8), age group of 40-59 years (51.1%; 95%CI 48.1-54.2), and in the poorest social classes (53.9%; 95%CI 50.2-57.7). The majority of medicines that act on the cardiovascular system, such as diuretics (C03) (78.0%; 95%CI 75.2-80.5), beta-blockers (C07) (62.7%; 95%CI 59.4-65.8), and the agents that work in the renin-angiotensin system (C09) (73.4%;, were obtained for free. Medicines that act on the respiratory system, such as agents against obstructive airway diseases (R03) (60.0%; 95%CI 52.7-66.9) were mostly paid with own resources. CONCLUSIONS: Free access to medicines for treatment of chronic diseases occurs to a considerable portion of the Brazilian population, especially for the poorest ones, indicating decreased socioeconomic inequalities, but with differences between regions and between some classes of medicines

Artistas sobre outras obras

Este número da Revista Estúdio assinala a crescente maturação de um espaço de comunicação algo alternativo, onde artistas falam de artistas, dão a conhecer obras menos conhecidas, e ocupam uma área de curadoria expontânea e paralela aos centros do arte world. Dá-se a palavra aos próprios criadores, e há seis anos que o seu olhar vem enriquecendo um património crescente, com especiais ligações aos países onde se fala as línguas ibéricas. A presença de obras de Portugal, Espanha, Brasil, Angola, Argentina, Perú, Venezuela, Bolívia e muitos outros países tornou-se habitual, fazendo da Estúdio uma instância da semiosfera (Lotman). Mais do que a presença, é a dimensão do conhecimento transmitido, a que se segue, naturalmente, o estabelecimento de novas teias de referência entre os artistas destes países: há novos grupos, novas cumplicidades, novas realizações dentro deste Estúdio, que completa seis anos de publicação persistente. A Revista Estúdio é também mais uma via disponível para o exercício da interpretação, através de descodificações mais informadas, mais negociadas, dos textos artísticos, pois são efectuadas por outros artistas. Reuniram-se nesta edição 24 artigos originais, mantendo a sua linha editorial inicial. O projecto mantém a sua componente de resistência, de plataforma de conhecimento para os pares, não abdicando também da validação externa, ou seja, do uso de protocolos de produção e transmissão de conhecimento. Falamos pois das normas de redação, de referenciação, de estruturação de textos e de articulação de argumentos, visuais ou verbais. Estabelece-se neste volume uma articulação entre cinema, vídeo, redes, escultura, instalação, fotografia, performance, banda desenhada, pintura, cerâmica, poesia concreta, livros de artista, sendo este conjunto não exaustivo testemunha do grau de hibridação que hoje o discurso artístico convoca. Apanhando-lhe o pulso, a Estúdio acompanha a arte desde os seus produtores, dos seus procedimentos, dos seus recursos, dos seus resultados. A Estúdio permite visitar muitos estúdios.info:eu-repo/semantics/publishedVersio