The EM algorithm for standard stochastic frontier models

The Expectation-Maximization (EM) algorithm is developed for the stochastic frontier models most used in practice with cross-section data. The resulting algorithms can be easily programmed into a computer and are shown to be worthy alternatives to general-purpose optimization routines currently used. The algorithms for the half normal and the exponential models have closed-form expressions whereas those for the truncated normal and gamma models will require the numerical solution of a nonlinear equation. Implementations of the EM algorithm either as a stand-alone routine or in accelerated form and also combined with Newton-like methods are discussed. We provide illustrations, along with R tools, for cost and production frontiers

Factors affecting the performance of Pantaneiro horses

This study aimed to assess the physical performance of Pantaneiro horses with and without equine infectious anemia (EIA) under functional conditions of cattle management. The horses were subjected to a performance test and split into two groups according to a completely randomized design: animals were chosen from populations testing positive and negative for EIA. Performance was measured as a function of a data envelopment analysis (DEA) model considering four outputs and one unitary input. The output measures were the distance achieved in the performance test, hematocrit as a weighted average over the test duration, respiratory rate as weighted average over the test duration, and the level of lactic acid at the test termination. Weights for the hematocrit and the respiratory rate output variables were determined by means of factor analysis. The performance score was a weighted average of the output variables with the weights defined by the averages of the optimum individual multipliers in the DEA analysis. Contextual variables of interest were age, horse weight, room temperature, and corporal temperature. Only groups and room temperature were statistically significant effects, as indicated by a bootstrap analysis. The performance of group positive for EIA is significantly lower than that of the group negative for EIA and room temperature has a negative effect.Instituto de Genética Veterinari

Factors affecting the performance of Pantaneiro horses

This study aimed to assess the physical performance of Pantaneiro horses with and without equine infectious anemia (EIA) under functional conditions of cattle management. The horses were subjected to a performance test and split into two groups according to a completely randomized design: animals were chosen from populations testing positive and negative for EIA. Performance was measured as a function of a data envelopment analysis (DEA) model considering four outputs and one unitary input. The output measures were the distance achieved in the performance test, hematocrit as a weighted average over the test duration, respiratory rate as weighted average over the test duration, and the level of lactic acid at the test termination. Weights for the hematocrit and the respiratory rate output variables were determined by means of factor analysis. The performance score was a weighted average of the output variables with the weights defined by the averages of the optimum individual multipliers in the DEA analysis. Contextual variables of interest were age, horse weight, room temperature, and corporal temperature. Only groups and room temperature were statistically significant effects, as indicated by a bootstrap analysis. The performance of group positive for EIA is significantly lower than that of the group negative for EIA and room temperature has a negative effect.Instituto de Genética Veterinari

Performance of grain sorghum gonotypes

Foram avaliadas treze linhagens e oito híbridos de sorgo granífero em dez ambientes, formados pela combinação de cinco locais e dois anos. O delineamento experimental utilizado foi o de blocos ao acaso com três repetições, sendo observadas as produções de grãos, de palhada, ciclo, peso de 1.000 grãos e o percentual de acamamento. Procedeu-se à análise da variância e da estabilidade de produção para os dois primeiros parâmetros. Quanto à produtividade de grãos, as linhas IPA 7300201, 7300206, 7300940, 7300980, 7300985, 7300988, 7301011 e o híbrido BR 300 apresentaram-se como estáveis ou adaptados a ambientes desfavoráveis. A produtividade de grãos e de palha apresentou correlação significativa, indicando ser possível selecionar genótipos para estes dois caracteres simultaneamente. O acamamento foi mais severo em Arcoverde e São Bento do Una em 1985, tendo os híbridos sido mais tolerantes do que as linhagens. O híbrido BR 300 deve ser recomendado para plantio, face a elevada produtividade de grãos, estabilidade de produção e baixa incidência de acamamento. A linhagem IPA 7301011 pode continuar a ser recomendada, especialmente no Sertão de Serra Talhada e áreas similares.The experiments were conducted aiming to evaluate 13 lines and 12 hybrids of grain sorghum under different environments composed by five sites and two years, in the Semi-Arid region of the State of Pernambuco. The experimental design used was in randomized complete blocks with three replications. The following characters were studied grain yield, straw production, cycle, 1000 grain weight, and lodging. The variance and stability analysis for grain yield and straw production showed that lines IPA 7300201, 7300206, 7300940, 7300980, 7300985, 7300988 and 7301011 as well as the hybrid BR 300 had acceptable level of stability for adaptation under unfavorable environments. The data for grain yield and straw production demonstrated that there was a significative correlation, indicating that a selection procedure for both characters can be made simultaneously. The lodging effect was more important in Arcoverde and São Bento do Una in 1985, where the lines were more susceptible than the hybrids. The sorghum hybrid BR 300 can be recommended due to the high grain yield, stability and tow lodging percentage. The line IPA 7301011 can still be used, specially in Serra Talhada and similar regions

Série de casos: avaliação de uma intervenção baseada em Mindfulness no estresse percebido e qualidade de vida de estudantes de medicina: Case series: evaluation of a Mindfulness-based intervention in perceived stress and quality of life of medical students

Introdução: estudantes universitários estão submetidos ao estresse resultante da sobrecarga de atividades curriculares e da constante pressão no ambiente acadêmico, o que pode gerar efeitos negativos nos estudos, no estado emocional e na saúde. O protocolo Mindfulness Based Stress Reduction (MBSR) tem demonstrado efeitos positivos para reduzir os sintomas associados ao estresse. Objetivos: avaliar os impactos do curso “Programa On-line de Qualidade de Vida Baseado em Mindfulness” na redução do estresse e na melhora da qualidade de vida em uma amostra de estudantes de medicina. Método: trata-se de uma pesquisa descritiva, exploratória e transversal, de amostragem do tipo “por conveniência”, que recrutou 33 graduandos em medicina da Univaço (Ipatinga, MG). Foram quantificados escores de qualidade de vida, estresse percebido, atenção e consciência plenas, facetas de Mindfulness e autocompaixão, antes e após participarem de um curso on-line de Mindfulness, com duração de 8 semanas. Resultados: a amostra apresentou média de idade de 22,6 anos na pré-intervenção e de 21,8 na pós-intervenção, predomínio do sexo feminino (pré-intervenção: 66,7% e pós-intervenção: 87,5%), prevalência de graduandos do 2° ano do curso na pré-intervenção (33%) e 4° ano do curso no pós-intervenção (50%) e preponderância de indivíduos solteiros (pré-intervenção: 93,9% e pós-intervenção: 100%). Houve diminuição da média de estresse percebido (36,3 para 23,6: redução de 34,9%) e das facetas de Mindfulness (122,7 para 120.5: redução de 1,8%), além de um aumento do escore total de qualidade de vida (67,6 para 78,8: ganho de 16,6%), da atenção e consciência plenas (47,5 para 60,0: ganho de 26,3%) e da autocompaixão (71,5 para 83,3: ganho de 16,3%). Conclusão: a presente pesquisa contribui para perspectivas de que as práticas de Mindfulness estão diretamente relacionadas à diminuição dos níveis de estresse e, consequentemente, a uma melhora da qualidade de vida de estudantes universitários

Multivariate optimization and validation of an analytical method for the determination of cadmium in wines employing ET AAS

This work describes the optimization and validation of a direct method employing electrothermal atomic absorption spectrometry (ET AAS) for the determination of cadmium in wine. The optimization step was carried out using a two-level full factorial design, involving the followings factors: pyrolysis time (10 s) and temperature (600 ºC), atomization temperature (1300 ºC) and modifier mass (15 µg). Under the optimized conditions, a characteristic mass of 0.7 pg and limits of detection and quantification of 0.030 and 0.100 µg L-1, respectively, were obtained using a sample volume of 20 µL. The precision expressed as relative standard deviation (RSD %) was 0.30, 0.37 and 0.49% for wines with cadmium concentrations of 1.286, 0.266 and 0.356 µg L-1, respectively. The accuracy of the new direct determination methodology applying ET AAS was assessed by comparison with an acid digestion methodology, also with determination by ET AAS, using five wine samples. The proposed method was applied for the determination of cadmium in 30 Brazilian wine samples. The cadmium content varied from 0.146 to 1.563 µg L-1; all these values are lower than the permissible maximum level stipulated by the International Organization of Vine and Wine (OIV) and also by Brazilian legislation, which is 10 µg L-1.O presente trabalho descreve a otimização e validação de um método para determinação direta de cádmio em amostras de vinho por espectrometria de absorção atômica com atomização eletrotérmica (ET AAS). A otimização foi realizada empregando um planejamento fatorial completo de 2 níveis, incluindo os fatores: tempo (10 s) e temperatura de pirólise (600 ºC), temperatura de atomização (1300 ºC) e massa de modificador (15 µg). Sob as condições otimizadas, foi encontrada uma massa característica de 0,7 pg, limite de detecção e quantificação de 0,030 e 0,100 µg L-1, respectivamente, para um volume de amostra de 20 µL. A precisão foi de 0,30, 0,37 e 0,49% (RSD) para amostras de vinho com concentrações de 1,286, 0,266 e 0.356 µg L-1, respectivamente. A exatidão da metodologia de determinação direta empregando ET AAS foi avaliada por comparação usando um método de digestão ácida e determinação também por ET AAS para cinco amostras de vinho. O método foi aplicado para determinação de cádmio em 30 amostras de vinhos brasileiros. A concentração de cádmio variou de 0,146 a 1,563 µg L-1, cujos valores estão abaixo do nível máximo permitido pela Organização Internacional de Vinha e Vinho (OIV) e pela legislação brasileira, 10 µg L-1.788794Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Selectivity of Pesticides used in Integrated Apple Production to the Lacewing, Chrysoperla externa

This research aimed to assess the toxicity of the pesticides abamectin 18 CE (0.02 g a.i. L-1), carbaryl 480 SC (1.73 g a.i. L-1), sulfur 800 GrDA (4.8 g a.i. L-1), fenitrothion 500 CE (0.75 g a.i. L-1), methidathion 400 CE (0.4 g a.i. L-1), and trichlorfon 500 SC (1.5 g a.i. L-1) as applied in integrated apple production in Brazil on the survival, oviposition capacity, and egg viability of the lacewing, Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) from Bento Gonçalves and Vacaria, Rio Grande do Sul State, Brazil. An attempt was made to study morphological changes caused by some of these chemicals, by means of ultrastructural analysis, using a scanning electronic microscope. Carbaryl, fenitrothion, and methidathion caused 100% adult mortality for both populations, avoiding evaluation of pesticides' effects on predator reproductive parameters. Abamectin and sulfur also affected the survival of these individuals with mortality rates of 10% and 6.7%, respectively, for adults from Bento Gonçalves, and were harmless to those from Vacaria at the end of evaluation. Trichlorfon was also harmless to adults from both populations. No compound reduced oviposition capacity. C. externa from Vacaria presented higher reproductive potential than those from Bento Gonçalves. In relation to egg viability, sulfur was the most damaging compound to both populations of C. externa. Ultrastructural analyses showed morphological changes in the micropyle and the chorion of eggs laid by C. externa treated with either abamectin or sulfur. The treatment may have influenced the fertilization of C. externa eggs and embryonic development. Sulfur was responsible for malformations in the end region of the abdomen and genitals of treated females. When applied to adults, abamectin, sulfur, and trichlorfon were harmless, while carbaryl, fenitrothion, and methidathion were harmful, according to the IOBC classification