CCET - DEST - Artigos publicados em periódicos

URI Permanente para esta coleçãohttps://repositorio.ufrn.br/handle/1/162

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An alternative model for on-line quality monitoring for variables
(International Journal of Production Economics, 2007) Ho, Linda Lee; Medeiros, Pledson Guedes de; Borges, Wagner
An alternative model for an on-line monitoring process for variables is presented in this paper. The characteristic of interest follows a normal distribution and changes of the distribution parameters are described by a two-state Markov chain. Items are produced independently and a single item is examined at every m manufactured items similar to an on-line quality procedure to monitor process for variables previously presented by Taguchi et al. [1989. Quality Engineering in Production Systems. McGraw-Hill, New York]. The objective of this study is to determine the optimal sampling interval m and the optimal control limit d that minimizes the expected cost function. A program using S-PLUS was developed to compare Taguchi’s and the alternative proposal. The alternative model provides a better performance than Taguchi’s, since it yields a lower cost and feasible parameters (control limits and sampling interval).
An INAR(1) process for modeling count time series with equidispersion, underdispersion and overdispersion
(Springer, 2017-04) Bourguignon, Marcelo; Weiss, Christian H.
We present a novel first-order nonnegative integer-valued autoregressive model for stationary count data processes with Bernoulli-geometric marginals based on a new type of generalized thinning operator. It can be used for modeling time series of counts with equidispersion, underdispersion and overdispersion. The main properties of the model are derived, such as probability generating function, moments, transition probabilities and zero probability. The maximum likelihood method is used for estimating the model parameters. The proposed model is fitted to time series of counts of iceberg orders and of cases of family violence illustrating its capabilities in challenging cases of overdispersed and equidispersed count data.
Analysis of augmented unreplicated factorial designs repeated in Time
(Quality and Reliability Engineering International, 2015-03-26) Vivacqua, Carla A.; Pinho, André Luís Santos de; Ho, Linda Lee
Unreplicated designs are fairly common in industrial applications; however, there is resistance to their use in agricultural science. In the agriculture community, there is still a belief that lack of replication may prevent the experimenter from getting useful conclusions. Nevertheless, sound statistical methods that permit valid comparisons in unreplicated studies are available for many types of designs. The objective of this paper is to present an analysis procedure for unreplicated designs combining typical characteristics found in industrial experimentation (factorial designs augmented with center points) and in agricultural applications (inclusion of control treatments and repeated measurements). We illustrate the method through a real experiment to evaluate the use of sugarcane by-products in chicken diet. Specifically, it is an unreplicated two-level factorial design with two additional runs (a center point and a control treatment), with experimental units measured in two periods of time. Replication was initially planned in the case study, but the actual treatment application led to an unreplicated design. The application of the proposed method allows interpretation of the data collected. We conclude that the appropriate use of unreplicated designs in agricultural and biological research may reduce overall costs and lessen the use of in vivo testing. Copyright © 2015 John Wiley & Sons, Ltd.
Arquitetura da informação e usabilidade: análise do processo de cadastro de autor e submissão de um artigo no periódico eletrônico bibliocanto da UFRN
(Universidade Federal do Rio Grande do Norte, 2015) Maia, Maria Aniolly Queiroz; Santa Rosa, José Guilherme; Pinho, Andre Luis Santos de; Carvalho, Caio Vitoriano de Nunes e; Gusmão, Eduardo Henrique Olímpio de; Sales Júnior, Francisco Monteiro de; Fonseca Júnior, José Nivaldo; 0000-0003-4485-1774
Este trabalho discorre sobre o processo de cadastro de autor e submissão de um artigo no periódico BiblioCanto, no Portal de Periódicos Eletrônicos da Universidade Federal do Rio Grande do Norte. A pesquisa com grupo de bibliotecários da UFRN envolveu análise contextual e entrevista em que foram avaliadas a arquitetura da informação e a usabilidade do periódico. Com os dados, foi possível identificar diversas falhas de design nos formulários de cadastro de autor e submissão de artigo neste Periódico. Com base nas informações obtidas, foram propostas melhorias, refinando o design e a arquitetura da informação do periódico.
Assessment of personal hygiene and practices of food handlers in municipal public schools of Natal, Brazil
(Elsevier, 2009) Campos, Ana Karina Couto; Cardonha, Ângela Maria Soares; Pinheiro, Liana Bacurau Galvão; Ferreira, Neide Rocha; Azevedo, Paulo Roberto Medeiros de; Stamford, Tânia Lúcia Montenegro
The aim of this study was to assess the hygiene practices of food handlers in municipal schools of Natal, Brazil, where 27 public schools were evaluated, using a checklist and microbiological analysis of hands. It was found that 74.1% of the handlers did not receive periodic training, 51.9% did not undergo annual health examinations and 100% did not practice proper hand hygiene, a situation that reflected significantly (p < 0.05) in hand contamination, in which fecal coliforms were detected on 55.6% of the hands analyzed. It was concluded that the schools studied did not have appropriate hygienic conditions, suggesting the need for interventions that ensure the quality of school food served to the children
Association between dyslipidemia and anthropometric indicators in adolescents
(Nutrición Hospitalaria, 2011) Lima, S. C. Vieira Cunha; Lyra, C. Oliveira; Pinheiro, L. Galvão Bacurau; Azevedo, P. R. Medeiros de; Arrais, R. F.; Pedrosa, L. F. Campos
The dyslipidemia associated with excess weight is a risk profile global call for cardiovascular disease (CVD). The aim of this study was to investigate the association between dyslipidemias and other risk factors for cardiovascular diseases (CVD) in adolescents, considering sexual maturation. A cross-sectional study was carried out with 432 adolescents from public schools, aged 10-19 years. The correlations between the variables from the lipid profile and the Body Mass Index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), sexual maturation, familial history and maternal education were evaluated using Pearson’s correlation coefficient. Low high-density lipoprotein cholesterol (HDL-C) was the most prevalent dyslipidemia (50.5%), regardless of gender. There were significant correlations between triglycerides and BMI (r = 0.30, p<0.01), WC (r = 0.32, p < 0.01) and WHtR (r = 0.33, p < 0.01). The linear model, which took into consideration sexual maturation, age and BMI, explain about 1 to 10.4% of the lipid profile variation. The low HDL-c was the most prevalent dyslipidemia in all adolescents and hypertriglyceridemia was most prevalent in overweight adolescents. Associations between dyslipidemias and anthropometric indicators (BMI and RCA) detected in this study can generate the hypothesis of the risk factors for CVD in adolescents.
A bayesian approach for modeling interval-valued variables
(Revista Brasileira de Biometria, 2014) Morales, Fidel Castro; Lima Neto, Eufrásio de Andrade
This paper proposes two Bayesian approaches to estimate the regression model coefficients considering interval-valued variables as response and explanatory variables. The first approach considers a more simple co-variance structure, while the second approach supposes a more general co-variance structure. The posterior distribution for the parameters was approximated considering Markov Chain Monte Carlo method (MCMC). A simulation study is presented and suggests the effectiveness of the sampling scheme in recovering the true values of the parameters and also indicates convergence of the parameter estimate algorithm. The new approaches are applied to real interval-valued data sets and their performance compared.
Cancer survivors’ self-efficacy to self-manage in the year following primary treatment
(Springer, 2014-07) Foster, C.; Breckons, M.; Cotterell, P.; Barbosa, Denize Araújo; Calman, L.; Corner, J.; Fenlon, D.; Foster, R.; Grimmett, C.; Richardson, A.; Smith, P. W.
Purpose Cancer survivors are increasingly expected to manage the consequences of cancer and its treatment for themselves. There is evidence that self-efficacy is important for successful self-management and that this can be enhanced with support. The purpose of this study was to assess self-efficacy to manage problems in the year following primary treatment. Methods This cross-sectional online survey included cancer survivors who had completed their treatment within the past 12 months. Self-efficacy was assessed and variables expected to be associated with self-efficacy were measured using validated scales including quality of life, well-being, illness perceptions, depression and social support. Results One hundred eighty-two respondents (mean age 50; 81 % female) completed the survey. They had been treated for a range of cancers; most commonly breast (45 %). Selfefficacy scores varied between individuals and according to the illness-related task to be managed. Respondents were least confident in managingfatigue and most confident inaccessing information about their cancer. Individuals most likely to report low self-efficacy were women, those experiencing higher levels of pain and/or depression, lower well-being scores, lower socio-economic status, low levels of social support, or a more negative perception of cancer. Conclusions Self-efficacy to self-manage problems faced as a consequence of cancer and its treatment can vary widely in the year following treatment. Fatigue may be particularly difficult to manage. Implications for Cancer Survivors Variations in self-efficacy highlight the importance of assessing specific problems faced and people’s confidence to manage them in order to tailor appropriate self-management support.
Choosing between Cox proportional hazards and logistic models for interval-censored data via bootstrap
(Journal of Applied Statistics, 2003) Corrente, José Eduardo; Chalita, Liciana V. A. S.; Moreira, Jeanete Alves
This work develops a new methodology in order to discriminate models for interval-censored data based on bootstrap residual simulation by observing the deviance difference from one model in relation to another, according to Hinde (1992). Generally, this sort of data can generate a large number of tied observations and, in this case, survival time can be regarded as discrete. Therefore, the Cox proportional hazards model for grouped data (Prentice&Gloeckler, 1978) and the logistic model (Lawless, 1982) can be fitted by means of generalized linear models. Whitehead (1989) considered censoring to be an indicative variable with a binomial distribution and fitted the Cox proportional hazards model using complementary log-log as a link function. In addition, a logistic model can be fitted using logit as a link function. The proposed methodology arises as an alternative to the score tests developed by Colosimo et al. (2000), where such models can be obtained for discrete binary data as particular cases from the Aranda-Ordaz distribution asymmetric family. These tests are thus developed with a basis on link functions to generate such a fit. The example that motivates this study was the dataset from an experiment carried out on a flax cultivar planted on four substrata susceptible to the pathogen Fusarium oxysoprum. The response variable, which is the time until blighting, was observed in intervals during 52 days. The results were compared with the model fit and the AIC values.
A combined npx X control chart to monitor the process mean in a two-stage sampling
(Quality and Reliability Engineering International, 2013-06) Sampaio, Elvis S.; Ho, Linda Lee; Medeiros, Pledson G. de
This paper proposes a new combined npx X control chart for monitoring the mean of a process. A sample of size n is split into two sub-samples of sizes n1 and n2 =n-n1, determined by an optimization search. The units of the first sub-sample are evaluated by attributes and plotted on an npx control chart. If this chart signals an out-of-control condition, then values of the quality characteristic of interest are collected from the units of the second sub-sample, and the sample mean is calculated and plotted on an X control chart. If both control charts signal, then the process is halted for adjustment. The possibility that all n items will not be inspected may lead to a reduction in both the cost and time spent on examining the sampled items. The performance of the proposed procedure is compared to that of two separate X and npx control charts. The proposed procedure exhibits superior performance to the X control chart for a variety of sample sizes, n, and shifts, d, of the target mean. The average time to signal (ATS) for the combined control chart was lower than that calculated for a single X or npx control chart, indicating that the combined control chart is an efficient tool for monitoring the process mean.
Comparative immunohistochemical expression of RANK, RANKL and OPG in radicular and dentigerous cysts
(Elsevier, 2011-05) Moraes, Maiara de; Lucena, Hévio Freitas de; Azevedo, Paulo Roberto Medeiros de; Queiroz, Lélia Maria Guedes; Costa, Antonio de Lisboa Lopes
Objective: Receptor activator of nuclear factor-kB (RANK), RANK ligand (RANKL) and osteoprotegerin (OPG) are members of the superfamily of ligands and receptors of tumour necrosis factor family involved in bone metabolism. The formation, differentiation and activity of osteoclasts are regulated by these proteins. To clarify the roles of osteoclast regulatory factors in cystic expansion of odontogenic cysts, expression of these proteins were analysed in radicular and dentigerous cysts. Design: The immunohistochemistry expression of these biomarkers were evaluated and measured in lining epithelium and fibrous capsule of the radicular (n = 20) and dentigerous cysts (n = 20). Results: A similar expression in lining epithelium was observed in the lesions. The fibrous capsule of dentigerous cyst showed a higher content of RANK-positive and RANKL-positive cells than fibrous capsule of radicular cyst. In the lining epithelium the RANKL/OPG ratio showed higher numbers of OPG-positive than RANKL-positive cells, whereas fibrous capsule of the cysts had a tendency to present a similar expression (OPG = RANKL). Conclusion: Ours findings indicate the presence of RANK, RANKL and OPG in cysts. Moreover, increased expression of OPG compared to RANKL in the lining epithelium could contribute to the differential bone resorption activity in theses lesions.
Conhecimentos, atitudes e prática do exame de Papanicolaou por mulheres, Nordeste do Brasil
(Scielo, 2009-02) Fernandes, José Veríssimo; Rodrigues, Silvia Helena Lacerda; Costa, Yuri Guilherme Alexandre Silva da; Silva, Luiz Cláudio Moura da; Brito, Alípio Maciel Lima de; Azevedo, Judson Welber Veríssimo de; Nascimento, Ermeton Duarte do; Azevedo, Paulo Roberto Medeiros de; Fernandes, Thales Allyrio Araújo de Medeiros
OBJETIVO: Analisar conhecimentos, atitudes e práticas das mulheres em relação ao exame citológico de Papanicolaou e a associação entre esses comportamentos e características sociodemográfi cas MÉTODOS: Inquérito domiciliar com abordagem quantitativa. Foram entrevistadas 267 mulheres com idade de 15 a 69 anos, selecionadas de forma estratifi cada aleatória, residentes no município de São José do Mipibu, RN, em 2007. Utilizou-se questionário com perguntas pré-codifi cadas e abertas, cujas respostas foram descritas e analisadas quanto à adequação dos conhecimentos, atitudes e prática das mulheres em relação ao exame preventivo de Papanicolaou. Foram realizados testes de associação entre as características sociodemográfi cas e os comportamentos estudados, com nível de signifi cância de 5%. RESULTADOS: Apesar de 46,1% das mulheres entrevistadas terem mostrado conhecimento adequado, proporções de adequação signifi cativamente maiores foram observadas em relação às atitudes e prática quanto ao exame: 63,3% e 64,4%, respectivamente. O maior grau de escolaridade apresentou associação com adequação dos conhecimentos, atitudes e prática, enquanto as principais barreiras para a realização do exame relatadas foram descuido, falta de solicitação do exame pelo médico e vergonha. CONCLUSÕES: O médico é a principal fonte de informação sobre o exame de Papanicolau. Entretanto, mulheres que vão a consultas com maior freqüência, embora apresentem prática mais adequada do exame, possuem baixa adequação de conhecimento e atitude frente ao procedimento, sugerindo que não estejam recebendo as informações adequadas sobre o objetivo do exame, suas vantagens e benefícios para sua saúde.
Controle on-line da taxa média de defeitos por item produzido numa produção finita
(Production, 2014-02) Teixeira, Carla Simone de Lima; Medeiros, Pledson Guedes de; Ho, Linda Lee
Este trabalho propõe uma abordagem para monitoramento da taxa média de defeitos por item produzido numa produção finita ou encomenda de N itens. A cada ciclo de m itens produzidos, inspecionam-se os últimos r itens. Em cada item inspecionado conta-se o número de defeitos e cada item é classificado como aprovado se o número de defeitos satisfizer o critério do limite de controle. Se todos os r itens forem aprovados, a produção continua, caso contrário interrompe-se a produção à procura de causas especiais. Os itens inspecionados são descartados somente quando há parada no processo. Após a produção de N itens, um lote adicional será produzido para completar a quantia encomendada, mas esses não passarão por inspeção. Será utilizada uma cadeia de Markov finita de estados discretos para determinar as probabilidades de mudança de estado. Elas são utilizadas nas expressões de custo para determinar a estratégia ótima de monitoração, que será obtida através da otimização de três parâmetros: intervalo amostral (m), tamanho da amostra retrospectiva (r) e o limite de controle (LC). Os parâmetros serão obtidos através de busca direta, de forma que se minimize a expressão do custo médio por item produzido. Um exemplo numérico ilustra a proposta.
Declining fisheries and increasing prices: the economic cost of tropical rivers impoundment
(Elsevier, 2020) Lima, Maria Alice Leite; Carvalho, Adriana Rosa; Nunes, Marcus Alexandre; Angelini, Ronaldo; Doria, Carolina Rodrigues da Costa
This work tests the null hypothesis that the coefficients of the total landings, landed values, mean catches and price per kg of migratory and resident species are constant over time following the installation of two large run-of-the-river hydroelectric dams in a large tropical river. To identify shifts in catches and economic returns due to river impoundment, we inspected daily landing data (25-year time series) and wholesale prices (19-year time series) for the Madeira River, the largest tributary of the Amazon River. Our results show that the period of decreasing catches and increasing prices observed for fisheries in the Madeira River matched the timings of the construction of the two dams. According to the results, both dams quickly changed catches and fish supply to market, which were immediately echoed in the price per kg of exploited fish species. Following the dam construction, prices rose for both fish that became scarce and fish that became abundant. Though catches declined 58% in 25 years, the price increased 49% over the same period, representing a high economic cost for the local population. Further, there was a clear decline in the catches of some species (e.g., the dourada and the curimatã), but increased catches of others (e.g., the sardine and the tucunaré). Moreover, some fluctuation patterns across years showed natural oscillations, or changes, in local habitats and even fishing efforts
A detailed framework for the characterization of rainfall climatology in semiarid watersheds
(Springer, 2019-08-05) Mutti, Pedro Rodrigues; Abreu, Lizandro Pereira de; Andrade, Lara de Melo Barbosa; Spyrides, Maria Helena Constantino; Lima, Kellen Carla; Oliveira, Cristiano Prestrelo de; Dubreuil, Vicent; Bezerra, Bergson Guedes
The identification of spatial and temporal rainfall climatology patterns is crucial for hydrometeorological studies over semiarid watersheds, which frequently face water distribution conflicts and socioeconomic issues due to water scarcity. Thus, the objective of this study was to propose a comprehensive approach for the characterization of rainfall climatology over semiarid watersheds. Monthly rainfall time series (1962–2015) with up to 30% of gaps measured in 56 rain gauges in the Piranhas-Açu Watershed—Brazilian semiarid region—were used. Data gaps were filled through a combination of simple spatial interpolation techniques. Principal component analysis and cluster analysis identified two homogeneous rainfall subregions in the basin: C1, in the upper portion, and C2, in the middle and lower portions. Rainfall volumes in C2 were up to 23.5% smaller than those in C1, due to orographic structures which contribute to aridity in this region. Rainfall anomalies were calculated in each cluster through the modified Rainfall Anomaly Index (mRAI) and were associated with the phases of the El Niño–Southern Oscillation (ENSO) and the Atlantic Meridional Mode (AMM). In years when the ENSO (AMM) was in its positive (negative) phase, there was a higher probability of occurrence of months with above-average rainfall, while the opposite was also true. Results showed that the effects of the patterns are mutually influenced, which has been previously found at larger scales. Finally, mRAI trends were identified through the Mann-Kendall test, which indicated significant negative trends in C1 and C2, especially during the wet season
Ecological interactions among phlebotomines (Diptera: Psychodidae) in an agroforestry environment of northeast Brazil
(Wiley, 2013-12) Pinheiro, Marcos Paulo Gomes; Silva, José Hilário Tavares; Cavalcanti, Katrine Bezerra; Azevedo, Paulo Roberto Medeiros de; Ximenes, Maria de Fátima Freire de Melo
Phlebotomine vectors transmit parasites and can cause visceral leishmaniasis (VL) or cutaneous leishmaniasis (TL). Phlebotomine females are hematophagous but need to ingest carbohydrates, possibly promoting the development of protozoan parasites in their digestive tract. The present study evaluated the species composition and abundance across several habitats in a metropolitan landscape, as well as associations among phlebotomines, plants, and local climatic parameters. Three consecutive monthly collections were carried out in an Atlantic Forest fragment, using CDC light traps in peridomestic areas and cashew, coconut, and mango tree.plantations. Eight species of phlebotomine were captured: Evandromyia evandroi, Lutzomyia longipalpis, Psathyromyia shannoni, Sciopemyia sordellii, Evandromyia walkeri, Psychodopygus wellcomei, Nyssomyia whitmani, and Nyssomyia intermedia, primarily from the forest environment. L. longipalpis was confirmed as a species adapted to anthropic environments, while P. wellcomei was shown to be predominately forest-dwelling. Phlebotomines exhibited diversified food consumption patterns in relation to carbohydrate sources. They fed on both native and exotic species of arboreal and shrubby vegetables and gramineous plants.
Economical control chart with supplementary rules to monitor the average number of defects
(The International Journal of Advanced Manufacturing Technology volume, 2015) Rocha, André Luiz Sena da; Medeiros, Pledson Guedes de; Ho, Linda Lee
This study proposes a procedure for an on-line process control system to monitor the average number of defects using a Shewhart-like chart with two sets of limits (viz., control and warning limits). After the production of m units, the mth item is inspected. If the number of defects exceeds the upper control limit or if, in a sequence of the last h inspections, all inspected items exhibit a number of defects between the warning and control limits, then the process is stopped for adjustment; otherwise, production continues. The properties of an ergodic Markov chain are used to obtain an expression for the average cost per item produced. The inspection interval (m), warning and control limits (W and C, respectively), and the sequence size (h) are determined by minimizing the average cost per produced item. A numerical example illustrates the proposed procedure.
Eficiência, gestão e meio ambiente na carcinicultura do Rio Grande do Norte
(2010-12-07) Silva, Jorge Luiz Mariano da; Sampaio, Luciano Menezes Bezerra
Experimento fatorial fracionado em parcelas sub-subdivididas: uma aplicação didática
(Revista da Estatística da Universidade Federal de Ouro Preto, 2014) Oliveira, Jordânia Furtado de; Souza, Fábio Azevedo de; Costa, Renato Tigre Martins da; Vivacqua, Carla Almeida
Com origem na agricultura, atualmente as técnicas de planejamento de experimentos são utilizadas nas mais diversas áreas do conhecimento científico, como na indústria e biometria. O desenvolvimento de um experimento é organizado em três etapas: planejamento, execução e análise de dados. No entanto, na maioria das vezes em que um curso no tema é ministrado, o aluno deixa de vivenciar na prática todas as etapas da experimentação. Diante disso, este trabalho tem como objetivo apresentar uma estratégia para incorporar a prática de todas as etapas de experimentação no ensino da disciplina de Planejamento de Experimentos.
Extended generalized extreme value distribution with applications in environmental data
(Journal of Mathematics and Statistics, 2015) Nascimento, Fernando; Bourguignon, Marcelo; Leão, Jeremias
In probability theory and statistics, the generalized extreme value (GEV) distribution is a family of continuous probability distributions developed within extreme value theory, which has wide applicability in several areas including hydrology, engineering, science, ecology and finance. In this paper, we propose three extensions of the GEV distribution that incorporate an additional parameter. These extensions are more flexible than the GEV distribution, i.e., the additional parameter introduces skewness and to vary tail weight. In these three cases, the GEV distribution is a particular case. The parameter estimation of these new distributions is done under the Bayesian paradigm, considering vague priors for the parameters. Simulation studies show the efficiency of the proposed models. Applications to river quotas and rainfall show that the generalizations can produce more efficient results than is the standard case with GEV distribution.

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