Statistical modelling of space weather extremes and process monitoring of rates and proportions

The first part of this work has been motivated by a multivariate space weather dataset. When the Sun releases high-energy particles into space due to a solar explosion, we experience magnetic storms, that once reaching Earth can last hours or days. Although solar flares emmited by the Sun cannot cause any harm to humans on Earth, if they are too severe they can damage machinery and techonology, such as satellites and radio communication. Thus, the modelling of extreme solar activity is important so we can be prepared for undesireable extreme events. Extreme value analysis can help professionals to understand the risks that severe geomagnetic field fluctuations can pose to Earth. For example, we can characterise the tail of the distribution of geomagnetic disturbances and the probability of extreme events. Hence, we perform a pairwise analysis for modelling the extremes of multiple bivariate processes of geomagnetic activity considering two copula models. The aim is to model the joint extremal probability and depict the pairwise extremal dependence structure between pairs of sites in two regions in Europe. The results show that the dependence structure differs in Northern and Southern Europe and that the dependence weakens as the distance increases. The second part of this work proposes a control chart for detecting small shifts in the mean of a double-bounded process, such as fractions or proportions, in the presence of control variables. For this purpose, we consider the cumulative sum control chart applied to different residuals of the beta regression model. We conduct an extensive Monte Carlo simulation study to evaluate and compare the performance of the proposed control chart with two other control charts in the literature in terms of run length analysis. The numerical results show that the proposed control chart is more sensitive to changes in the process than its competitors and that the quantile residual is the most suitable residual to be used in our proposal. Finally, based on the quantile residual, we present and discuss applications to real and simulated data to show the applicability of the proposed control chart

AVALIAÇÃO DA OCORRÊNCIA DE ESTRO E DESENVOLVIMENTO FOLICULAR EM FÊMEAS SUÍNAS NA LACTAÇÃO COM MANEJO DE DESMAME DE 28 DIAS

O desmame de fêmeas suínas é realizado na grande maioria aos 21 dias de lactação, contudo, uma grande discussão acerca da mudança de manejo de 21 para 28 dias, sem ocorrência da manifestação do estro durante a lactação e interferência no intervalo desmame cio (IDC) vem sendo discutida. Foram avaliadas 114 fêmeas suínas de duas granjas diferentes, quanto a manifestação de estro pelo reflexo de tolerância ao homem (RTH) e desenvolvimento folicular por ultrassonografia. Os resultados mostraram que não houve ocorrência de estro durante a lactação no período de 28 dias e nenhuma interferência no IDC em 100% das fêmeas avaliadas

Planos Municipais de Saúde do Estado do Tocantins: uma análise com foco no enfrentamento da obesidade

This documentary analysis evaluated the scope of addressing obesity in the Municipal Health Plans (PMS) in the state of Tocantins, Brazil, since the growing prevalence of obesity in Brazil should put its confrontation at the center of public health action and management instruments. To analyze the PMS performance from 2018 to 2021 in the 139 municipalities of this state, 17 terms related to obesity were selected and had their frequency and context in the PMS verified. Of the existing 139 PMS, 129 (92.8%) were evaluated. “Health academy” and “SISVAN” were the most frequent terms used, whereas “obesity” appeared in only 28% of the plans, totaling 71 mentions. Of these, only 32.4% were directly related to combating the disease, mainly in the health regions of Bico do Papagaio and Médio Norte Araguaia. Relevant contexts for addressing obesity included the characterization of the epidemiological profile, tables of action goals, and indicators. PMS’s role in combating obesity is absent in more than 70% of municipalities in Tocantins, which points to the urgent inclusion of this disease within the management instruments.O objetivo deste estudo foi avaliar a abrangência do enfrentamento da obesidade nos Planos Municipais de Saúde (PMS) do Estado do Tocantins, dado que, diante da crescente prevalência da obesidade no Brasil, seu enfrentamento deveria estar no foco de ação da saúde pública e previsto nos instrumentos de gestão. Trata-se de um estudo qualitativo, com análise documental, que analisou os PMS no período de vigência de 2018 a 2021 nos 139 municípios desse estado. Foram selecionados dezessete termos relacionados à obesidade e verificada a frequência e contexto nos PMS. Do total de 139 PMS, foram avaliados 129 (92,8%). Os termos “academia da saúde” e “Sisvan” foram os mais frequentes, e “obesidade” apareceu em apenas 28% dos planos, totalizando 71 citações. Destas, somente 32,4% relacionavam-se diretamente com o enfrentamento da doença, com destaque nas regiões de saúde Bico do Papagaio e Médio Norte Araguaia. Os contextos relevantes de abordagem da obesidade mais frequentes foram a caracterização da situação epidemiológica, quadros de metas de ações e indicadores. Concluiu-se que o enfrentamento da obesidade pactuado nos PMS está ausente em mais de 70% dos municípios do Tocantins, e que ações de direcionamento para inclusão dessa doença dentro dos instrumentos de gestão são urgentes

Biochemical quality of cowpea beans grown under water-deficit maintained with hydrogel

Investigations related to the effects of the hydrogel use in a water-deficit conditions on the biochemical composition of the harvested products are scarce. The aim of this study was to verify the influence of hydrogel on the biochemical response of cowpea beans produced under water-deficit in southern Tocantins. The experiment was a randomized complete block design with four replications. The treatments were obtained in a 2x5 factorial scheme, being: two sources of hydrogel (Hydroplan-EB HyC and Polim-Agri PP) and five concentrations (0, 5, 10, 15, and 20kg ha-1). After harvesting, the grains of cowpea, BRS Vinagre cultivar, were ground and chemically analyzed. The oil content of the seeds agreed with the reference values. The use of Polim-Agri PP promoted the best levels of amino acids (0.38mg g-1) and proteins (243.22mg g-1) of the grains. The carbohydrate content of them (Ȳ= 81.44mg g-1) was better using Hydroplan-EB HyC, regardless of the concentration applied. The application of 6.28kg ha-1 of Polim-Agri PP provided the highest starch content (842g mg-1). The use of hydrogel improves the biochemical quality of cowpea beans produced under water deficit in southern Tocantins

Kumaraswamy regression model with Aranda-Ordaz link function

In this work, we introduce a regression model for double-bounded variables in the interval (0, 1) following a Kumaraswamy distribution. The model resembles a generalized linear model, in which the response’s median is modeled by a regression structure through the asymmetric Aranda-Ordaz parametric link function. We consider the maximum likelihood approach to estimate the regression and the link function parameters altogether. We study large sample properties of the proposed maximum likelihood approach, presenting closed-form expressions for the score vector as well as the observed and Fisher information matrices. We briefly present and discuss some diagnostic tools. We provide numeric evaluation of the finite sample inferences to show the performance of the estimators. Finally, to exemplify the usefulness of the methodology, we present and explore an empirical application

Improved testing inferences for beta regressions with parametric mean link function

Beta regressions are widely used for modeling random variables that assume values in the standard unit interval, (0, 1), such as rates, proportions, and income concentration indices. Parameter estimation is typically performed via maximum likelihood, and hypothesis testing inferences on the model parameters are commonly performed using the likelihood ratio test. Such a test, however, may deliver inaccurate inferences when the sample size is small. It is thus important to develop alternative testing procedures that are more accurate when the sample contains only few observations. In this paper, we consider the beta regression model with parametric mean link function and derive two modified likelihood ratio test statistics for that class of models. We provide simulation evidence that shows that the new tests usually outperform the standard likelihood ratio test in samples of small to moderate sizes. We also present and discuss two empirical applications

Residual‐based CUSUM beta regression control chart for monitoring double‐bounded processes

This paper proposes a control chart useful for detecting small shifts in the mean of a double-bounded process, such as fractions and proportions, in the presence of control variables. For this purpose, we consider the cumulative sum (CUSUM) control chart applied to different residuals of the beta regression model. We conduct an extensive Monte Carlo simulation study to evaluate and compare the performance of the proposed control chart with two other control charts in the literature in terms of run length analysis. The numerical results show that the proposed control chart is more sensitive to detect changes in the process than its competitors and that the quantile residual is the most suitable residual to be used in our proposal. Finally, based on the quantile residual, we present and discuss applications to real and simulated data to show the applicability of the proposed control chart