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The article proposes a new regression based on the generalized odd log-logistic family for interval-censored data. The survival times are not observed for this type of data, and the event of interest occurs at some random interval. This family can be used in interval modeling since it generalizes some popular lifetime distributions in addition to its ability to present various forms of the risk function. The estimation of the parameters is addressed by the classical and Bayesian methods. We examine the behavior of the estimates for some sample sizes and censorship percentages. Selection criteria, likelihood ratio tests, residual analysis, and graphical techniques assess the goodness of fit of the fitted models. The usefulness of the proposed models is red shown by means of two real data sets.

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Several statistical models have been proposed in recent years, among them is the semiparametric regression. In medicine, there are several situations in which it is impracticable to consider a linear regression for statistical modeling, especially when the data contain explanatory variables that present a nonlinear relationship with the response variable. Another common situation is when the response variable does not have a unimodal shape, and it is not possible to adopt distributions belonging to the symmetric or asymmetric classes. In this context, a semiparametric heteroskedastic regression is proposed based on an extension of the normal distribution. Then, we show the usefulness of this model to analyze the cost of prostate cancer surgery. The predictor variables refer to two groups of patients such that one group receives a multimodal local anesthetic solution (Preemptive Target Anesthetic Solution) and the second group is treated with neuraxial blockade (spinal anesthesia/traditional standard). The other relevant predictor variables are also evaluated, thus allowing for the in-depth interpretation of the predictor variables with a nonlinear effect on the dependent variable cost. The penalized maximum likelihood method is adopted to estimate the model parameters. The new regression is a useful statistical tool for analyzing medical data.

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The work proposes a new family of survival models called the Odd log-logistic generalized Neyman type A long-term. We consider different activation schemes in which the number of factors M has the Neyman type A distribution and the time of occurrence of an event follows the odd log-logistic generalized family. The parameters are estimated by the classical and Bayesian methods. We investigate the mean estimates, biases, and root mean square errors in different activation schemes using Monte Carlo simulations. The residual analysis via the frequentist approach is used to verify the model assumptions. We illustrate the applicability of the proposed model for patients with gastric adenocarcinoma. The choice of the adenocarcinoma data is because the disease is responsible for most cases of stomach tumors. The estimated cured proportion of patients under chemoradiotherapy is higher compared to patients undergoing only surgery. The estimated hazard function for the chemoradiotherapy level tends to decrease when the time increases. More information about the data is addressed in the application section.

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We define two new flexible families of continuous distributions to fit real data by compoun-ding the Marshall-Olkin class and the power series distribution. These families are very competitive to the popular beta and Kumaraswamy generators. Their densities have linear representations of exponentiated densities. In fact, as the main properties of thirty five exponentiated distributions are well-known, we can easily obtain several properties of about three hundred fifty distributions using the references of this article and five special cases of the power series distribution. We provide a package implemented in R software that shows numerically the precision of one of the linear representations. This package is useful to calculate numerical values for some statistical measurements of the generated distributions. We estimate the parameters by maximum likelihood. We define a regression based on one of the two families. The usefulness of a generated distribution and the associated regression is proved empirically.

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We define the odd log-logistic exponential Gaussian regression with two systematic components, which extends the heteroscedastic Gaussian regression and it is suitable for bimodal data quite common in the agriculture area. We estimate the parameters by the method of maximum likelihood. Some simulations indicate that the maximum-likelihood estimators are accurate. The model assumptions are checked through case deletion and quantile residuals. The usefulness of the new regression model is illustrated by means of three real data sets in different areas of agriculture, where the data present bimodality.

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Silver complexes containing 1,10-phenanthroline as a coordinated ligand have been of great interest due to their antibacterial and antifungal pharmacological properties. In this paper, we describe the synthesis of a new partial inclusion complex of bis(1,10-phenanthroline)silver(I) salicylate in ß-cyclodextrin (ß-CD) which was synthesized with a good yield. The compounds were characterized by FTIR, 1H, 13C NMR including 1H-1H COSY, TGA/DSC, elemental analysis (CHN), and X-ray powder diffraction. The results suggest the presence of non-covalent interactions such as hydrogen bonds, van der Waals forces, and hydrophobic interactions in the formation of the partial inclusion compound between ß-CD and bis(1,10-phenanthroline)silver(I) salicylate [Ag(phen)2]salH. Additionally, an in silico prediction of 1,10-phenanthroline biological activities was carried out and the acquired data suggests several potential targets associated with the antimicrobial activity of this compound and its silver complex. Most predicted targets are related to antimicrobial virulence and resistance that are a serious threat to global public health. The inclusion compound showed a higher inhibiting growth of Candida albicans than the free complex [Ag(phen)2]salH indicating that the formation of the inclusion complex with ß-CD increases the bioavailability of the antimicrobial active species [Ag(phen)2]+ of the new silver(I) compound.

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We propose a new extended regression model based on the logarithm of the generalized odd log-logistic Weibull distribution with four systematic components for the analysis of survival data. This regression model can be very useful and could give more realistic fits than other special regression models. We obtain the maximum likelihood estimates of the model parameters for censored data and address influence diagnostics and residual analysis. We prove empirically the importance of the proposed regression by means of a real data set (survival times of the captive snakes) from a study carried out at the Herpetology Laboratory of the Butantan Institute in São Paulo, Brazil.

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We propose a new survival model for lifetime data in the presence of surviving fraction and obtain some of its properties. Its genesis is based on extensions of the promotion time cure model, where an extra parameter controls the heterogeneity or dependence of an unobserved number of lifetimes. We construct a regression model to evaluate the effects of covariates in the cured fraction. We discuss inference aspects for the proposed model in a classical approach, where some maximum likelihood tools are explored. Further, an expectation maximization algorithm is developed to calculate the maximum likelihood estimates of the model parameters. We also perform an empirical study of the likelihood ratio test in order to compare the promotion time cure and the proposed models. We illustrate the usefulness of the new model by means of a colorectal cancer data set.

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Renal insufficiency is a serious medical and public health problem worldwide. Recently, although many surveys have been developed to identify factors related to the lifetime of patients with renal insufficiency, controversial results from several studies suggest that researches should be conducted by region. Thus, in this study we aim to predict and identify factors associated with the lifetime of patients with chronic renal failure (CRF) in the metropolitan area of Maringá, Paraná State, Brazil, based on the generalized additive models for location, scale and shape (GAMLSS) framework. Data used in this study were collected from the Maringá Kidney Institute and comprehends 177 patients (classified with CRF and mostly being treated under the Brazilian Unified National Health System) enrolled in a hemodialysis program from 1978 up to 2010. By using this approach, we concluded that in other regions, gender, kidney transplant indicator, antibodies to hepatitis B and antibodies to hepatitis C are significant factors that affect the expected lifetime.

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Cure fraction models are useful to model lifetime data with long-term survivors. We propose a flexible four-parameter cure rate survival model called the log-sinh Cauchy promotion time model for predicting breast carcinoma survival in women who underwent mastectomy. The model can estimate simultaneously the effects of the explanatory variables on the timing acceleration/deceleration of a given event, the surviving fraction, the heterogeneity, and the possible existence of bimodality in the data. In order to examine the performance of the proposed model, simulations are presented to verify the robust aspects of this flexible class against outlying and influential observations. Furthermore, we determine some diagnostic measures and the one-step approximations of the estimates in the case-deletion model. The new model was implemented in the generalized additive model for location, scale and shape package of the R software, which is presented throughout the paper by way of a brief tutorial on its use. The potential of the new regression model to accurately predict breast carcinoma mortality is illustrated using a real data set.

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Renal insufficiency is a serious medical and public health problem worldwide. Recently, although many surveys have been developed to identify factors related to the lifetime of patients with renal insufficiency, controversial results from several studies suggest that researches should be conducted by region. Thus, in this study we aim to predict and identify factors associated with the lifetime of patients with chronic renal failure (CRF) in the metropolitan area of Maringá, Paraná State, Brazil, based on the generalized additive models for location, scale and shape (GAMLSS) framework. Data used in this study were collected from the Maringá Kidney Institute and comprehends 177 patients (classified with CRF and mostly being treated under the Brazilian Unified National Health System) enrolled in a hemodialysis program from 1978 up to 2010. By using this approach, we concluded that in other regions, gender, kidney transplant indicator, antibodies to hepatitis B and antibodies to hepatitis C are significant factors that affect the expected lifetime.

A insuficiência renal crônica é um grave problema clínico e de saúde pública no mundo inteiro. Recentemente, apesar de muitas pesquisas já realizadas para identificar os fatores relacionados à evolução dos pacientes renais crônicos, os resultados conflitantes entre diversos estudos sugerem a necessidade de pesquisas por região. Portanto, o estudo busca predizer e identificar os fatores associados à evolução dos pacientes com insuficiência renal crônica (IRC) na área metropolitana de Maringá, Estado do Paraná, Brasil, com base nos modelos aditivos generalizados para localização, escala e forma (GAMLSS). Os dados utilizados neste estudo foram coletados no Instituto do Rim de Maringá e incluem 177 pacientes (classificados com IRC, a maioria tratada no Sistema Único de Saúde) inclusos no programa de hemodiálise entre 1978 e 2010. Através dessa abordagem, concluímos que em outras regiões, gênero, indicação para transplante renal e anticorpos aos vírus das hepatites B e C são fatores significativos que afetam a sobrevivência esperada.

La insuficiencia renal representa un problema médico y de salud pública serio en todo el mundo. Recientemente, pese a los muchos estudios que se han desarrollado para identificar factores relacionados con la esperanza de vida de los pacientes con insuficiencia renal, los resultados controvertidos de algunos estudios sugieren que las investigaciones deberían realizarse por regiones. No obstante, en este trabajo pretendemos predecir e identificar los factores asociados con la esperanza de vida de pacientes con fallo renal crónico (FRC) en el área metropolitana de Maringá, Estado de Paraná, Brasil, basado en el marco de modelos aditivos generalizados para ubicación, escala y forma (GAMLSS por sus siglas en inglés). Los datos usados en este estudio fueron recogidos del Instituto del riñón de Maringá y comprende a 177 pacientes (clasificados con FRC y en su mayoría siendo tratados en el Sistema Único de Salud), inscritos en un programa de hemodiálisis desde 1978 hasta 2010. Usando este enfoque, concluimos que en otras regiones, género, indicador de trasplante de riñón, anticuerpos a la hepatitis B y anticuerpos a la hepatitis C son factores significativos que afectan a la esperanza de vida.

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The aim of the present study was to investigate the impact of oral diseases, socioeconomic status, and family environmental factors on changes in the perception of oral health-related quality of life (OHRQoL) in adolescents. A prospective cohort study was conducted in Juiz de Fora, Minas Gerais, Brazil, with a sample of 286 twelve-year-old adolescents from public and private schools, selected by means of multistage random sampling. The adolescents were clinically examined for dental caries experience (number of decayed, missing, and filled teeth - DMFT index), presence of bleeding, and orthodontic treatment needs. They were asked to complete the Brazilian version of the Child Perceptions Questionnaire (CPQ11-14). In addition, parents answered a questionnaire about their socioeconomic status and family environmental characteristics. After 3 years, the adolescents were contacted again to participate in the research. Logistic regression models, with explanatory variables assessed both individually and jointly, were used to determine which independent variables impacted longitudinally on OHRQoL. The final result demonstrated that only DMFT explained part of the response variability in CPQ11-14 scores. In conclusion, caries experience was an important predictor of OHRQoL in adolescents followed up for 3 years.

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PURPOSE: To compare 2-year cumulative survival rates in first permanent molars (FPM) with and without MIH and to investigate risk factors associated with caries incidence. MATERIALS AND METHODS: A total of 142 children aged 5 to 6 years were recruited from all public schools in Botelhos, Minas Gerais, Brazil and 536 FPM were examined. A questionnaire was designed to collect sociodemographic background and behavioural information about children and their parents. Caries in FPM was recorded per surface in accordance with WHO methodology at baseline and once every 6 months over a period of two years. The survival analysis was conducted using the Weibull regression model with cure fraction. RESULTS: MIH was present in 16.19% of children. The 2-year cumulative survival rates for FPM with and without MIH showed statistically significant differences, and visible plaque on anterior teeth had an effect on the survival rates. CONCLUSION: Children with MIH and visible plaque on anterior teeth at baseline had a high risk for developing new caries lesions in their FPM over the course of two years. These variables should be considered in caries risk assessment in paediatric dental care.

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Abstract The aim of the present study was to investigate the impact of oral diseases, socioeconomic status, and family environmental factors on changes in the perception of oral health-related quality of life (OHRQoL) in adolescents. A prospective cohort study was conducted in Juiz de Fora, Minas Gerais, Brazil, with a sample of 286 twelve-year-old adolescents from public and private schools, selected by means of multistage random sampling. The adolescents were clinically examined for dental caries experience (number of decayed, missing, and filled teeth - DMFT index), presence of bleeding, and orthodontic treatment needs. They were asked to complete the Brazilian version of the Child Perceptions Questionnaire (CPQ11-14). In addition, parents answered a questionnaire about their socioeconomic status and family environmental characteristics. After 3 years, the adolescents were contacted again to participate in the research. Logistic regression models, with explanatory variables assessed both individually and jointly, were used to determine which independent variables impacted longitudinally on OHRQoL. The final result demonstrated that only DMFT explained part of the response variability in CPQ11-14 scores. In conclusion, caries experience was an important predictor of OHRQoL in adolescents followed up for 3 years.

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This study aimed to evaluate the impact of dental caries treatment on oral health-related quality of life (OHRQoL) among schoolchildren and the responsiveness of the Child Perceptions Questionnaire (CPQ8-10 ) instrument. Brazilian schoolchildren, 8-10 yr of age, were randomly selected and assigned to two groups--dental caries treatment (DCT) and caries-free (CF)--according to their caries experience [decayed, missing, or filled primary teeth (dmft) and decayed, missing or filled secondary teeth (DMFT) values of ≥ 0]. The CPQ8-10 instrument was administered at baseline and at 4 wk of follow-up (i.e. 4 wk after completion of dental treatment). In the DCT group, increases in CPQ8-10 scores were observed between the baseline and follow-up results. However, longitudinal evaluation of the CF group demonstrated no statistically significant difference in CPQ8-10 scores. Responsiveness of the CPQ8-10 instrument (magnitude of change in CPQ8-10 scores) in the DCT group was greater (effect size >0.7) than in the CF group. The findings of this study show that dental caries treatment has an important impact on OHRQoL of children. The CPQ8-10 was considered an acceptable instrument for longitudinal measurement of changes in OHRQoL.

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The postmastectomy survival rates are often based on previous outcomes of large numbers of women who had a disease, but they do not accurately predict what will happen in any particular patient's case. Pathologic explanatory variables such as disease multifocality, tumor size, tumor grade, lymphovascular invasion, and enhanced lymph node staining are prognostically significant to predict these survival rates. We propose a new cure rate survival regression model for predicting breast carcinoma survival in women who underwent mastectomy. We assume that the unknown number of competing causes that can influence the survival time is given by a power series distribution and that the time of the tumor cells left active after the mastectomy for metastasizing follows the beta Weibull distribution. The new compounding regression model includes as special cases several well-known cure rate models discussed in the literature. The model parameters are estimated by maximum likelihood. Further, for different parameter settings, sample sizes, and censoring percentages, some simulations are performed. We derive the appropriate matrices for assessing local influences on the parameter estimates under different perturbation schemes and present some ways to assess local influences. The potentiality of the new regression model to predict accurately breast carcinoma mortality is illustrated by means of real data.

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To evaluate socioeconomic, familiar and clinical risk variables associated to caries increment in the children's permanent dentition from seven to 10 years participating in a dental health program.Material and Methods:A sample of 301 children from nine public schools participated in the æAlways Smiling ProgramÆ took part in this study. They were evaluated for dental caries through dmft and DMF-T indexes along 2 years, and their parents completed a socio-environmental questionnaire containing questions on their income, education and family environment. Survival analysis using Kaplan-Meier method was used to evaluate the effect of the independent variables on caries increment.Results:We verified that socio-environmental variables were not associated with caries increment, while children with experience in primary dentition were 1.5 times more likely to develop caries in permanent dentition compared to those who did not have this experience.Conclusion:Schoolchildren presenting dental caries in primary dentition on baseline had higher risk of developing caries in permanent dentition and this variable should be taken in consideration by managers of dental health programs when prioritizing groups with higher care needs...

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The log-Burr XII regression model for grouped survival data is evaluated in the presence of many ties. The methodology for grouped survival data is based on life tables, where the times are grouped in k intervals, and we fit discrete lifetime regression models to the data. The model parameters are estimated by maximum likelihood and jackknife methods. To detect influential observations in the proposed model, diagnostic measures based on case deletion, so-called global influence, and influence measures based on small perturbations in the data or in the model, referred to as local influence, are used. In addition to these measures, the total local influence and influential estimates are also used. We conduct Monte Carlo simulation studies to assess the finite sample behavior of the maximum likelihood estimators of the proposed model for grouped survival. A real data set is analyzed using a regression model for grouped data.

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Objetivou-se determinar as respostas fisiológicas e bioquímicas associadas ao uso de etileno e 1-metilciclopropeno (1-MCP) na conservação pós-colheita de lichias, assim como a influência desses tratamentos isolados ou combinados no escurecimento desses frutos. Após a colheita, foram aplicados os seguintes tratamentos: sem aplicação de 1-MCP ou etileno; etileno (20µL L-1, por 6 horas); 1-MCP (300nL L-1, por 12 horas) e etileno (20µL L-1, por 6 horas) + 1-MCP (300nL L-1, por 6 horas). Após os tratamentos, os frutos foram armazenados a 5°C e 90 por cento UR durante 30 dias, sendo avaliados a cada 10 dias (+3 dias de comercialização simulada a 25°C e 65 por cento UR). Avaliou-se a produção de etileno, taxa respiratória, sólidos solúveis (SS), perda de massa fresca, coloração (luminosidade - L* e a*) e atividade da polifenoloxidase (PPO). A produção de etileno e taxa respiratória não apresentaram diferenças significativas entre os tratamentos e os SS decresceram ao longo do armazenamento, mas também sem diferenças entre os tratamentos. A atividade da enzima PPO foi aumentada, sendo correlacionada com os índices decrescentes de L* e a* presentes nos frutos, ocorrendo, paralelamente, aumento da perda de massa dos frutos. Conclui-se que o escurecimento do pericarpo da lichia está relacionado à perda de massa fresca e aumento da atividade da PPO e que nenhum dos tratamentos utilizados evitou o escurecimento dos frutos.

The objective was to determine the physiological and biochemical changes associated with the use of ethylene and 1-methylcyclopropene (1-MCP) on postharvest conservation of lychees as well as the influence of these treatments alone or in combination on skin browning of fruit. After harvest, it was applied the following treatments: without application of 1-MCP or ethylene, ethylene (20mL L-1 for 6 hours), 1-MCP (300nL L-1 for 12h) and ethylene (20mL L-1 for 6 hours) + 1-MCP (300nL L-1 for 6 hours). After treatments, fruits were stored at 5°C and 90 percent RH for 30 days and were evaluated every 10 days (+3 days of simulated marketing at 25°C and 65 percent RH). The ethylene production, respiration rate, soluble solids (SS), weight loss, color (lightness - L * and a*) and polyphenoloxidase activity (PPO) were evaluated. Ethylene production and respiration rate showed no significant differences between treatments, and SS decreased over the storage, but there was also no difference between treatments. The enzyme activity showed an increase in PPO, which was correlated to the decreasing rates of L * and a*, occurring in parallel, increased fruit weight loss. It is concluded that the skin browning of lychee is related to weight loss and increased activity of PPO, and that none of the treatments prevented the sking browning of fruit.

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The objective was to determine the physiological and biochemical changes associated with the use of ethylene and 1-methylcyclopropene (1-MCP) on postharvest conservation of lychees as well as the influence of these treatments alone or in combination on skin browning of fruit. After harvest, it was applied the following treatments: without application of 1-MCP or ethylene, ethylene (20mL L-1 for 6 hours), 1-MCP (300nL L-1 for 12h) and ethylene (20mL L-1 for 6 hours) + 1-MCP (300nL L-1 for 6 hours). After treatments, fruits were stored at 5°C and 90% RH for 30 days and were evaluated every 10 days (+3 days of simulated marketing at 25°C and 65% RH). The ethylene production, respiration rate, soluble solids (SS), weight loss, color (lightness - L * and a*) and polyphenoloxidase activity (PPO) were evaluated. Ethylene production and respiration rate showed no significant differences between treatments, and SS decreased over the storage, but there was also no difference between treatments. The enzyme activity showed an increase in PPO, which was correlated to the decreasing rates of L * and a*, occurring in parallel, increased fruit weight loss. It is concluded that the skin browning of lychee is related to weight loss and increased activity of PPO, and that none of the treatments prevented the sking browning of fruit.

Objetivou-se determinar as respostas fisiológicas e bioquímicas associadas ao uso de etileno e 1-metilciclopropeno (1-MCP) na conservação pós-colheita de lichias, assim como a influência desses tratamentos isolados ou combinados no escurecimento desses frutos. Após a colheita, foram aplicados os seguintes tratamentos: sem aplicação de 1-MCP ou etileno; etileno (20µL L-1, por 6 horas); 1-MCP (300nL L-1, por 12 horas) e etileno (20µL L-1, por 6 horas) + 1-MCP (300nL L-1, por 6 horas). Após os tratamentos, os frutos foram armazenados a 5°C e 90% UR durante 30 dias, sendo avaliados a cada 10 dias (+3 dias de comercialização simulada a 25°C e 65% UR). Avaliou-se a produção de etileno, taxa respiratória, sólidos solúveis (SS), perda de massa fresca, coloração (luminosidade - L* e a*) e atividade da polifenoloxidase (PPO). A produção de etileno e taxa respiratória não apresentaram diferenças significativas entre os tratamentos e os SS decresceram ao longo do armazenamento, mas também sem diferenças entre os tratamentos. A atividade da enzima PPO foi aumentada, sendo correlacionada com os índices decrescentes de L* e a* presentes nos frutos, ocorrendo, paralelamente, aumento da perda de massa dos frutos. Conclui-se que o escurecimento do pericarpo da lichia está relacionado à perda de massa fresca e aumento da atividade da PPO e que nenhum dos tratamentos utilizados evitou o escurecimento dos frutos.