Modelling non-proportional hazard for survival data with different systematic components

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.

Factors that can influence the survival rates of coral snakes (Micrurus corallinus) for antivenom production.

Envenoming and deaths resulting from snakebites are a particularly important public health problem in rural tropical areas of Africa, Asia, Latin America, and New Guinea. In 2015, The Lancet highlighted snake-bite envenoming as a neglected tropical disease and urged the world to increase antivenom production. In Brazil, around 20,000 snakebites occur per year affecting mostly agricultural workers and children, of which 1% is caused by coral snakes (Micrurus sp.). Although human envenoming by coral snakes is relatively rare due to their semifossorial habits and nonaggressive behavior, they are always considered severe due to the neurotoxic, myotoxic, hemorrhagic, and cardiovascular actions of their venom, which is highly toxic when compared to the venom of other Brazilian venomous snakes as Bothrops sp. (pit vipers), Crotalus sp. (rattlesnakes), and Lachesis sp. (bushmasters). The production of antivenom serum is an important public health issue worldwide and the maintenance of venomous snakes in captivity essential to obtain high-quality venom. Though more than 30 species of Brazilian coral snakes exist, the specific antivenom serum produced with the venom of two species, Micrurus corallinus and M. frontalis, is able to neutralize the accidents caused by the genus in general. M. corallinus is considered a difficult species to maintain in captivity and concerned about this difficulty the Laboratory of Herpetology (LH) at Instituto Butantan, over the last 10 yr, has given special attention to its maintenance in captivity. In more than 20 yr of maintenance, LH has made some changes to improve Micrurus captive husbandry and welfare. The objective of this study was to verify the factors influencing the survival rates of coral snakes in captivity through data generated from 289 M. corallinus from the LH snake facility in the last 10 yr. We observed that survival rates increased significantly with the improvement of nutritional adequacy that included freezing food items before offering them to coral snakes, as well as the development of a new pasty diet to force-feed anorexic animals. Another important factor responsible for increasing life expectancy was the shift of the cage's substrate from Sphagnum to bark in 2010, aiding in the eradication of Blister Disease, which used to be responsible for the death of several coral snakes in previous years.

Factors that can influence the survival rates of coral snakes (Micrurus corallinus) for antivenom production

Envenoming and deaths resulting from snakebites are a particularly important public health problem in rural tropical areas of Africa, Asia, Latin America, and New Guinea. In 2015, The Lancet highlighted snake-bite envenoming as a neglected tropical disease and urged the world to increase antivenom production. In Brazil, around 20,000 snakebites occur per year affecting mostly agricultural workers and children, of which 1% is caused by coral snakes (Micrurus sp.). Although human envenoming by coral snakes is relatively rare due to their semifossorial habits and nonaggressive behavior, they are always considered severe due to the neurotoxic, myotoxic, hemorrhagic, and cardiovascular actions of their venom, which is highly toxic when compared to the venom of other Brazilian venomous snakes as Bothrops sp. (pit vipers), Crotalus sp. (rattlesnakes), and Lachesis sp. (bushmasters). The production of antivenom serum is an important public health issue worldwide and the maintenance of venomous snakes in captivity essential to obtain high-quality venom. Though more than 30 species of Brazilian coral snakes exist, the specific antivenom serum produced with the venom of two species, Micrurus corallinus and M. frontalis, is able to neutralize the accidents caused by the genus in general. M. corallinus is considered a difficult species to maintain in captivity and concerned about this difficulty the Laboratory of Herpetology (LH) at Instituto Butantan, over the last 10 yr, has given special attention to its maintenance in captivity. In more than 20 yr of maintenance, LH has made some changes to improve Micrurus captive husbandry and welfare. The objective of this study was to verify the factors influencing the survival rates of coral snakes in captivity through data generated from 289 M. corallinus from the LH snake facility in the last 10 yr. We observed that survival rates increased significantly with the improvement of nutritional adequacy that included freezing food items before offering them to coral snakes, as well as the development of a new pasty diet to force-feed anorexic animals. Another important factor responsible for increasing life expectancy was the shift of the cage's substrate from Sphagnum to bark in 2010, aiding in the eradication of Blister Disease, which used to be responsible for the death of several coral snakes in previous years.

Richards growth model and viability indicators for populations subject to interventions.

In this work we study the problem of modeling identification of a population employing a discrete dynamic model based on the Richards growth model. The population is subjected to interventions due to consumption, such as hunting or farming animals. The model identification allows us to estimate the probability or the average time for a population number to reach a certain level. The parameter inference for these models are obtained with the use of the likelihood profile technique as developed in this paper. The identification method here developed can be applied to evaluate the productivity of animal husbandry or to evaluate the risk of extinction of autochthon populations. It is applied to data of the Brazilian beef cattle herd population, and the the population number to reach a certain goal level is investigated.

Richards growth model and viability indicators for populations subject to interventions

In this work we study the problem of modeling identification of a population employing a discrete dynamic model based on the Richards growth model. The population is subjected to interventions due to consumption, such as hunting or farming animals. The model identification allows us to estimate the probability or the average time for a population number to reach a certain level. The parameter inference for these models are obtained with the use of the likelihood profile technique as developed in this paper. The identification method here developed can be applied to evaluate the productivity of animal husbandry or to evaluate the risk of extinction of autochthon populations. It is applied to data of the Brazilian beef cattle herd population, and the the population number to reach a certain goal level is investigated.

Neste trabalho estudamos o problema de identificação do modelo de uma população utilizando um modelo dinâmico discreto baseado no modelo de crescimento de Richards. A população é submetida a intervenções devido ao consumo, como no caso de caça ou na criação de animais. A identificação do modelo permite-nos estimar a probabilidade ou o tempo médio de ocorrência para que se atinja um certo número populacional. A inferência paramétrica dos modelos é obtida através da técnica de perfil de máxima verossimilhança como desenvolvida neste trabalho. O método de identificação desenvolvido pode ser aplicado para avaliar a produtividade de criação animal ou o risco de extinção de uma população autóctone. Ele foi aplicado aos dados da população global de gado de corte bovino brasileiro, e é utilizado na investigação de a população atingir um certo número desejado de cabeças.

Conhecimento dos médicos pediatras sobre saúde bucal no município de Ribeirão Preto, SP. / Pediatricians? oral health knowledge in Ribeirão Preto city, São Paulo state, Brazil.

A cárie dentária, doença mais comum na infância, pode ser prevenida com ajuda dos médicos pediatras, que estão em posição peculiar para orientar os pais quanto à saúde oral das crianças. O objetivo deste estudo foi avaliar o nível de conhecimento, atitudes e praticas dos médicos pediatras que atuam no município de Ribeirão Preto-SP com relação à carie dentária. Foram selecionados todos os médicos cadastrados como especialistas em Pediatria no CREMESP (n=177) para responderem a um questionário. Os resultados mostraram que 95,16% dos pediatras relataram possuir informações sobre os fatores etiológicos da cárie e seus métodos de prevenção, sendo que os fatores de risco mais citados foram higiene oral precária e a inadequada escovação dentária (100%), seguida por frequência de ingestão de açúcar e amamentação com mamadeira (96,77%). Verificou-se ainda que 100% dos entrevistados prescrevem dieta a seus pacientes e examinam a cavidade oral dos mesmos e todos acreditam ser importantes visitas rotineiras ao consultório odontológico. De acordo com os profissionais 95,16% relataram necessitar de mais informações sobre a prevenção das doenças orais. Concluiu-se que os resultados são positivos em relação à saúde bucal, porém faz-se necessário maior esclarecimento do assunto para que informações e ações mais corretas sejam repassadas aos pais.

Dental caries, the most common childhood disease, can be prevented with the help of pediatricians, who are in a privileged position to advise parents about their children?s oral health. The objective of this study was to evaluate the level of knowledge, attitudes, and conducts of pediatricians working in the city of Ribeirão Preto, São Paulo state, regarding dental caries. All physicians registered as pediatrics specialists with the Conselho Regional de Medicina de São Paulo (CREMESP ? state medical council) (n=177) were selected to answer a questionnaire. The results showed that 95.16% of the pediatricians reported having information about the etiological factors of caries and prevention methods. The most stated risk factors were poor oral hygiene and insufficient toothbrushing (100%), followed by excessive sugar intake and bottle feeding (96.77%). It was also found that 100% of the interviewees prescribe diets to their patients and check their mouths on routinephysical examination. In addition, all subjects believe it is important that patients visit their dentists frequently. Of the interviewed pediatricians, 95.16% stated they require more information about the prevention of oral diseases. It is concluded that the results regarding oral health are positive, but there is a need for better clarification about the issue so that more precise information and conducts can be given to the children?s parents.