Modeling the Microbial Shelf-Life of Chicken Mince Added Rosemary Extract

Abstract Using the non-linear regression model, the present study aims to develop sample mathematical models for the microbial flora by utilization of the antimicrobial effects of rosemary (Rosmarinus officinalis) extracts at different concentrations (0.5, 1, 1.5, and 2%) on the raw chicken mince. For this purpose, 5 experimental groups were established for each plant extract. The samples (100 g each) treated with plant extract at different concentrations were vacuum-packaged under aseptic conditions. The packaged samples were kept in refrigerator (4ºC). The microbiological analyses of (total mesophilic aerobic bacteria, total coliform group bacteria, S. aureus, total yeast-mold, and total psychrophilic bacteria) were performed on 0th, 1st, 3rd, 5th, 7th, and 10th days of storage. When compared to the control group the treatment with RE resulted in a decrease in the microbial numbers by 2.5 log units for TMAB number, by 3.5 log units for S. aureus number, by 3,5 log units for TMY number and by 1.5 log units for TP bacteria on the final day of storage. In establishing the model, the plant extract and storage period were used as variable parameters, whereas the shelf-life was used as output parameter. The changes in shelf-life of raw chicken minces by storage period and extract concentration were modeled, the compliance of obtained mathematical models was tested using Variance Analysis Method (ANOVA) and regression and determination coefficients (R2) were determined. After determining their compliance of models based on R2 values, the estimated values and real values were compared. As a result of study, it was determined that R2 values of raw chicken mince models by total mesophilic aerobic bacteria, S. aureus, total coliform bacteria, total yeast/mold, and total psychrophilic bacteria during the storage period were found to range between 0.743 and 0.978 and the models representing the microbial change were found to have a high level of compliance.

ANOVA to Compare Three Methods to Track COVID-19 in Nine Countries / ANOVA en la comparación de tres métodos para rastrear COVID-19 en nueve países

ABSTRACT A new coronavirus denominated first 2019-nCoV and later SARS-CoV-2 was found in Wuhan, China in December of 2019. This paper compares three mathematical methods: nonlinear regression, SIR, and SEIR epidemic models, to track the covid-19 disease in nine countries affected by the SARS-CoV-2 virus, to help epidemiologists to know the disease trajectory, considering initial data in the pandemic, mainly 100 days from the beginning. To evaluate the results obtained with the three methods one-way ANOVA is applied. The average of predicted infected cases with SARS-CoV-2, obtained with the mentioned methods was: for United States of America 1,098,508, followed by Spain with 226,721, Italy with 202,953, France with 183,897 United Kingdom with 182,190, Germany with 159,407, Canada with 58,696, Mexico with 50,366 and Argentina with 4,860 in average. The one-way ANOVA does not show a significant difference among the results of the projected infected cases by SARS-CoV-2, using nonlinear regression, SIR, and SEIR epidemic methods. The above could mean that initially any method can be used to model the pandemic course.

RESUMEN Un nuevo coronavirus denominado primero 2019-nCoV y más tarde SARS-CoV-2 fue encontrado en Wuhan, China en diciembre de 2019. El objetivo de este trabajo es comparar tres métodos matemáticos: regresión no lineal, modelos epidemiológicos SIR y SEIR, para rastrear la enfermedad del COVID-19 en nueve países infectados por el virus SARS-CoV-2, con el propósito de ayudar al epidemiólogo a conocer el curso de la pandemia, considerando principalmente sus primeros 100 días. Para evaluar los resultados obtenidos de la aplicación de los tres métodos, se aplicó ANOVA de una vía. El número promedio de casos infectados con SARS-CoV-2, obtenidos con los tres métodos descritos son: para Estados Unidos 1,098,508, seguido de España con 226,721, Italia con 202,953, Francia con 183,897 Reino Unido con 182,190, Alemania con 159,407, Canadá con 58,696, México con 50,366 y Argentina con 4,860 en promedio. El ANOVA de una vía no muestra diferencias significativas entre los resultados de los casos infectados proyectados por SARS-CoV-2, utilizando la regresión no lineal y los métodos SIR and SEIR. Lo anterior podría señalar que cualquiera de los tres métodos estudiados puede modelar el curso de la pandemia en las condiciones descritas para cada uno.

Nonlinear quantile regression to describe the dry matter accumulation of garlic plants / Regressão quantílica não linear para descrever o acúmulo de matéria seca de alho

ABSTRACT: The objective of this study was to adjust nonlinear quantile regression models for the study of dry matter accumulation in garlic plants over time, and to compare them to models fitted by the ordinary least squares method. The total dry matter of nine garlic accessions belonging to the Vegetable Germplasm Bank of Universidade Federal de Viçosa (BGH/UFV) was measured in four stages (60, 90, 120 and 150 days after planting), and those values were used for the nonlinear regression models fitting. For each accession, there was an adjustment of one model of quantile regression (τ=0.5) and one based on the least squares method. The nonlinear regression model fitted was the Logistic. The Akaike Information Criterion was used to evaluate the goodness of fit of the models. Accessions were grouped using the UPGMA algorithm, with the estimates of the parameters with biological interpretation as variables. The nonlinear quantile regression is efficient for the adjustment of models for dry matter accumulation in garlic plants over time. The estimated parameters are more uniform and robust in the presence of asymmetry in the distribution of the data, heterogeneous variances, and outliers.

RESUMO: Este trabalho teve como objetivo ajustar modelos de regressão quantílica não linear para o estudo do acúmulo de matéria seca total em plantas de alho ao longo do tempo, e compará-los com modelos ajustados pelo método dos mínimos quadrados. A matéria seca total de nove acessos de alho pertencentes ao Banco de Germoplasma de Hortaliças da Universidade Federal de Viçosa (BGH/UFV) foi avaliada em quatro períodos (60, 90, 120 e 150 dias após plantio), e estes valores foram utilizados para o ajuste de modelos de regressão - não linear - logística. Para cada acesso, foram ajustados um modelo de regressão quantílica (τ=0,5) e um modelo pela metodologia dos mínimos quadrados. Para avaliar a qualidade de ajuste dos modelos foi utilizado o Critério de Informação de Akaike. Os acessos foram agrupados pelo algoritmo UPGMA, utilizando as estimativas dos parâmetros com interpretação biológica como variáveis. A regressão quantílica não linear foi eficiente no ajuste de modelos para descrição do acúmulo de matéria seca ao longo do tempo. As estimativas de parâmetros foram mais uniformes e robustas na presença de dados assimétricos, variâncias heterogêneas e de valores discrepantes.

Chanter model: nonlinear modeling of the fruit growth of cocoa / Modelo Chanter: modelagem não linear do crescimento de frutos do cacaueiro

ABSTRACT: The growth of plants and animals can be described through a growth curve. This curve is given by the equation of a nonlinear model, such as the Logistic model and the Gompertz model. The objective of this study was to adjust the Chanter model, as well as Logistic and Gompertz, using a set of cocoa (clone Sial-105) fruit whose length and diameter measurements were evaluated from 30 to 180 days after pollination, every 15 days. The Chanter model is a hybrid between the Logistic model and Gompertz model whose parameters can be interpreted similarly. A comparison of the quality of fit between the models was made using the following statistical measures: the Akaike's information criterion (AIC), the Akaike's weights criterion, Bayesian information criterion (BIC), residual standard deviation (RSD),the adjusted coefficient of determination (R²aj) and the measures of non-linearity Box's bias and curvature of Bates and Watts. It was verified that the Chanter model is the most suitable one among the studied models for modeling the cocoa data.

RESUMO: O crescimento de plantas e animais pode ser descrito por meio de uma curva. Essa curva é dada pela equação de um modelo não linear, como o modelo Logístico e o modelo Gompertz. O objetivo deste trabalho foi ajustar o modelo Chanter, assim como o Logístico e Gompertz, utilizando um conjunto de dados do fruto do cacaueiro do clone SIAL - 105, cujas medidas de comprimento e diâmetro foram avaliadas de 30 até 180 dias após a polinização, a cada 15 dias. O modelo Chanter é um híbrido entre o modelo Logístico e o modelo Gompertz cujos parâmetros podem ser interpretados similarmente. A avaliação da qualidade do ajuste entre os modelos foi feita utilizando as seguintes medidas estatísticas: o critério de informação de Akaike (AIC), o critério Peso de Akaike, o critério de informação de Bayes (BIC), o desvio padrão residual (DPR), o coeficiente de determinação ajustado (R²aj) e as medidas de não linearidade, vício de Box e curvatura de Bates e Watts. Verificou-se que o modelo Chanter dentre os modelos estudados neste trabalho é o mais adequado para o ajuste aos dados do fruto do cacaueiro.

Quantile regression of nonlinear models to describe different levels of dry matter accumulation in garlic plants / Regressão quantílica de um modelo não linear para descrição de diferentes níveis de acúmulo de matéria seca em plantas de alho

ABSTRACT: Plant growth analyses are important because they generate information on the demand and necessary care for each development stage of a plant. Nonlinear regression models are appropriate for the description of curves of growth, since they include parameters with practical biological interpretation. However, these models present information in terms of the conditional mean, and they are subject to problems in the adjustment caused by possible outliers or asymmetry in the distribution of the data. Quantile regression can solve these problems, and it allows the estimation of different quantiles, generating more complete and robust results. The objective of this research was to adjust a nonlinear quantile regression model for the study of dry matter accumulation in garlic plants (Allium sativum L.) over time, estimating parameters at three different quantiles and classifying each garlic accession according to its growth rate and asymptotic weight. The nonlinear regression model fitted was a Logistic model, and 30 garlic accessions were evaluated. These 30 accessions were divided based on the model with the closest quantile estimates; 12 accessions were classified as of lesser interest for planting, 6 were classified as intermediate, and 12 were classified as of greater interest for planting.

RESUMO: Análises de crescimento de plantas são importantes, pois geram informações sobre a demanda e os cuidados necessários para cada etapa de seu desenvolvimento. Modelos de regressão não linear são apropriados para descrever curvas de crescimento por apresentarem parâmetros com interpretação prática biológica. Entretanto, estes modelos apresentam informações em termos médios, e estão sujeitos a problemas no ajuste proporcionados por possíveis valores extremos ou assimetria na distribuição dos dados. A regressão quantílica pode contornar estes problemas, e ainda permite estimativas de diferentes quantis, gerando resultados mais completos e robustos. Assim, o objetivo deste trabalho foi ajustar um modelo de regressão quantílica não linear para o estudo do acúmulo de matéria seca em plantas de alho (Allium sativum L.) ao longo do tempo, estimando seus parâmetros em três diferentes quantis e classificando cada acesso de alho de acordo com sua taxa de crescimento e peso assintótico. O modelo de regressão não linear ajustado foi o Logístico, e foram utilizados 30 acessos de alho. Estes foram divididos de acordo com a curva do quantil de estimativas mais próximas, sendo classificados 12 acessos como de baixo interesse para o plantio, 6 de interesse intermediário e 12 como de alto interesse.

Relationship between body and testicular measurements in young buffalo bulls in Cuba / Relación entre las mediciones corporales y testiculares en búfalos jóvenes en Cuba / Relação entre medidas corporais e testiculares em búfalos jovens em Cuba

Abstract Background: appropriate selection of sires holds great importance in plans to genetically improve and raise buffalos. Objective: to obtain a statistical model that provides accurate associations between body and testicular measurements intended for selection of Bufalypso breed sires. Methods: measurements of body weight (BW), thoracic perimeter (TP), and scrotal circumference (SC) from 649 buffalos aged 2 to 36 months, were used to obtain the models corresponding to the associations between these traits. The statistical significance of the model and the model's parameters were evaluated using a one-way analysis of variance. The best-fit model was established by calculating determination coefficients (R2) and mean squared error (SE). Results: the most adequate regression model between thoracic perimeter and body weight was TP = 19.89*BW0.37, with 99% and 0.03 for R2 and, SE, respectively. The best association between scrotal circumference and body weight was obtained with the model SC = 1.13*BW0.51, with values of 89% for R2 and of 0.1 for SE. The model that best expressed the relationship between scrotal circumference and thoracic perimeter was SC = 0.02*TP0.89, with R2 = 89% and SE = 0.01. Conclusion: nonlinear models described better the association between body and testicular measurements than the linear ones. These results suggest that nonlinear models are effective for selecting buffalo sires.

Resumen Antecedentes: la selección de sementales tiene gran importancia en los planes de mejora genética y cría de búfalos. Objetivo: obtener los modelos estadísticos que mejor relacionan las mediciones corporales y testiculares en machos jóvenes de raza Bufalypso para su uso en la selección de futuros sementales. Métodos: se midió el peso corporal (BW), el perímetro torácico (TP) y la circunferencia escrotal (SC) a 649 búfalos, entre 2 y 36 meses de edad, obteniéndose los modelos correspondientes a las relaciones entre estas características. La significación estadística de los modelos y parámetros se evaluó mediante análisis de varianza de una vía. El mejor modelo de ajuste se determinó a partir de cálculos de los coeficientes de determinación (R2) y el error cuadrático medio (SE). Resultados: el modelo más adecuado entre el perímetro torácico y el peso corporal fue TP = 19,89*BW0.37, con valores de R2 de 99% y de 0,03 para SE. La mejor relación entre la circunferencia escrotal y el peso corporal se obtuvo con el modelo SC = 1,13*BW0.51, con un R2 igual al 89% y un SE de 0,1. El modelo que mejor expresó la relación entre la circunferencia escrotal y el perímetro torácico fue SC = 0,02*TP0.89, con valores de 89% para R2 de y de 0,01 para SE. Conclusión: los modelos no lineales describieron mejor la relación entre las mediciones corporales y testiculares que los modelos lineales. Los resultados sugieren que la selección de los sementales sería más efectiva utilizando modelos no lineales.

Resumo Antecedentes: a seleção de reprodutores é muito importante nos programas de melhoramento e criação de búfalos. Objetivo: obter modelos estatísticos que melhor relacionem as medidas corporais e testiculares em machos jovens da raça Bufalypso, para serem usados na seleção de futuros reprodutores. Métodos: foi medido o peso corporal (BW), o perímetro torácico (TP) e a circunferência escrotal (SC) de uma amostra de 649 búfalos, com idades entre 2 e 36 meses. A significância estatística dos modelos e dos parâmetros foi avaliada pela análise de variância. O melhor modelo de ajuste foi determinado a partir do cálculo dos coeficientes de determinação (R2) e o quadrado médio do erro (SE). Resultados: o modelo mais adequado para o perímetro torácico e o peso corporal foi PT = 19,89*BW0,37 com R2 de 99% e SE de 0,03. A melhor relação entre circunferência escrotal e o peso corporal foi obtida com o modelo SC = 1,13*BW0,51 com R2 de 89% e SE de 0,1. O modelo que melhor representou a relação entre a circunferência escrotal e o perímetro torácico foi SC = 0,02*TP0,89 com valores de R2 de 89% e SE 0,01. Conclusão: os modelos não lineares descreveram melhor a relação entre as mensurações corporais e as testiculares do que os modelos lineares. Esses resultados sugerem que a seleção dos reprodutores seria mais eficaz utilizando os modelos não lineares.

Evaluation methods of individual technology maturity based on SCI-covered papers and patent data / 中华医学图书情报杂志

Objective To establish the evaluation methods of individual technology maturity based on SCI-covered papers and patent data using Gartner's Hype Cycle.Methods The SCI-covered papers and patent data were ana-lyzed by nonlinear regression analysis in combination with traditional X-radiography and photo-acoustic tomo-graphy, and represented as the bell-shaped curve and S-shaped curve for judging the technology maturity.Results The individual technology maturity was consistent with the qualitative review of experts.Conclusion The individual technology described in SCI-covered papers and patent data can be used in primary evaluation of its maturity.

Curva de crescimento de diferentes linhagens de frango de corte caipira / Growth curve of different strains of broiler chickens

Objetivou-se identificar o modelo de regressão não linear mais adequado para descrever a curva de crescimento de quatro linhagens de frangos caipira e compará-las entre as linhagens. Foram utilizadas 100 aves, sendo 13 machos e 12 fêmeas de cada uma das linhagens. Foram testados 13 modelos de regressão não linear e, após a seleção do melhor modelo, foi verificada a igualdade de parâmetros e identidade de modelos não lineares. O peso médio aos 77 dias de idade foi de 3.017, 2.781, 2.724 e 2.587kg para a Pesadão, Mista, Carijó e Pescoço Pelado, respectivamente. O modelo Quadrático Logarítmico apresentou melhor ajuste dos dados para as linhagens Pesadão, Carijó e Mista, segundo o quadrado médio do resíduo e desvio médio absoluto. Para a linhagem Pescoço Pelado, os critérios estatísticos apontaram como mais adequado o modelo Polinomial Inverso, seguido do Quadrático Logarítmico. As curvas de crescimento entre machos e entre fêmeas das linhagens foram diferentes, assim, como as curvas de crescimento de machos e fêmeas dentro de linhagens. A divergência entre as classes avaliadas foi atribuída à taxa de decréscimo de peso, parâmetro c do modelo Quadrático Logarítmico. O modelo Quadrático Logarítmico pode ser utilizado para descrever a curva de crescimento das quatro linhagens. A linhagem Pesadão tem o crescimento mais acelerado e a linhagem Pescoço Pelado tem o crescimento mais lento. A partir do 35o dia de idade, sugere-se o ajuste do manejo nutricional para alterar a curva de crescimento e atender a legislação vigente e o mercado consumidor.

This study aimed to identify the nonlinear regression model more adequate to describe and compare the growth curve of four strains of broiler chickens. One hundred birds were used, 13 males and 12 females from each strains. There were tested 13 models of nonlinear regression and after that the best model was used to test the parameters equality and the models identity. The average weight at 77 days of age was 3.017, 2.781, 2.724 and 2.587kg to the strains Hulking, Mixed, Carijó and Naked Neck, respectively. The Quadratic Logarithmic model showed better fit the data from Hulking, Carijó and Mixed strains, according to the mean square and mean absolute deviation tests. To the Naked Neck line the statistical criteria showed as more suitable the Inverse Polynomial model followed by the Quadratic Logarithmic. The males and females growth curves were different between and within the strains. The divergence between the evaluated classes was attributed to the decrease of weight rate, c parameter of Quadratic Logarithmic model. Quadratic Logarithmic model could be used to describe the growth curve of the four strains. The Hulking strain presented the faster and the Naked Neck strain presented the slowest growth. The feed system with the objective of change the growth curve must be adopted by the 35th day of age, to attend the current legislation and the consumer market.

Comparison and analysis on water extraction process of the preferred SuXingErChen Syrup by orthogonal test and multivariate nonlinear regression analysis / 中国生化药物杂志

Objective To select optimum water extraction process of SuXingErChen Syrup by orthogonal test and multivariate nonlinear regression analysis.Methods Naringin was extracted by water, Used the naringin content and extraction rate of extractum as indexes.Based on the orthogonal test and multivariate nonlinear regression analysis to make sure the best way for extracting naringin from SuXingErChen Syrup.Results The optimal conditions of water extraction process was that the herbs were added seven times the amount of water without infiltration,extracted two times with 80 min each time,which was selected by multivariate nonlinear regression analysis.Conclusion The process of water extraction for the preferred Su XingErChen Syrup is exact, high effective and suitable for production needs.

Fitting nonlinear autoregressive models to describe coffee seed germination / Ajuste de modelos não lineares autorregressivos na descrição da germinação se sementes de café

Cumulative germination of coffee has a longitudinal behavior mathematically characterized by a sigmoidal model. In the seed germination evaluation, the study of the germination curve may contribute to better understanding of this process. The aim of this study was to evaluate the goodness of fit of Logistic and Gompertz models, with independent and first-order autoregressive errors structure, AR (1), in the description of coffee (Coffea arabica L.) line Catuai vermelho IAC 99 germination, at five different potential germination. The data used were from an experiment conducted in 2011 at the Seed Analysis Laboratory of the Federal University of Lavras. The Logistic and Gompertz nonlinear models were appropriately adjusted to the percentage germination data. The Gompertz model with first-order autoregressive errors structure was the best to describe the germination process.

A germinação acumulada de sementes de café tem um comportamento longitudinal matematicamente caracterizado por um modelo sigmoidal. Na avaliação de sementes, o estudo da curva de germinação pode contribuir para melhor entendimento de tal processo. O objetivo deste estudo foi avaliar a qualidade do ajuste dos modelos Logístico e Gompertz, com estrutura de erros independentes e autorregressivos de primeira ordem, AR(1), na descrição de germinação de sementes de café (Coffea arabica L.), linhagem Catuaí vermelho IAC 99, em cinco diferentes potenciais de germinação. Os dados utilizados foram provenientes de um experimento conduzido no ano de 2011 no Laboratório de Análises de Sementes da Universidade Federal de Lavras. Os modelos não lineares Logístico e Gompertz se ajustaram adequadamente aos dados de porcentagem de germinação acumulada. O modelo Gompertz com estrutura de erros autorregressivos de primeira ordem apresentou-se como o melhor para descrever o processo germinativo ao longo do tempo.

An Evaluation of Usage and Utilization of Generic Drugs by Clinical Medicine Departments Using a Questionnaire of Chain Community Pharmacies in Japan / 医薬品情報学

The creation of the National Health Insurance program has greatly contributed to giving Japan the world’s highest level of life expectancy.  However, the cost of medical care in Japan has increased as a result of an aging society.  In response to this reality, the Japanese government initiated a campaign to promote the use of generic drugs (GEs).  In order to clarify some of the trends that contribute to different clinical medicine department usages of GEs, we carried out a survey of 400 pharmacies.  The survey data was analyzed using linear regression analysis.  Analysis of linear equations derived “utilization” that indicated ease of use of GEs, and a “saturation acceptable value (maximum allowed)” that indicated usage of GEs.  The breakdown for different clinical medicine department usages of GEs was determined as the following: psychosomatic medicine or psychiatry was 11±0.13%, internal medicine was 29±0.18%, orthopedics was 18±0.14%, ophthalmology or otolaryngology was 15±0.14%, other departments was 17±0.15%.  Furthermore, the highest utilization derived by linear regression analysis was orthopedics.  The highest acceptable saturation value was for psychosomatic medicine or psychiatry, while the lowest acceptable saturation value was orthopedics.  The results of the study confirm the importance of establishing evaluation methods for GE usage, and that linear regression analysis is a powerful tool for revealing trends in GE usage among different departments.  Additionally, the study suggests that determining GE spread measures is valuable, since they can serve as an aid to future pharmaceutical administration consideration.

Proposta de modelagem não-linear do desempenho germinativo de sementes de milho híbrido / Nonlinear proposal modeling of seed germination performance of hybrid corn seeds

Este trabalho foi desenvolvido com o objetivo de ajustar um modelo de regressão não-linear para estimar o desempenho germinativo de sementes de três lotes comerciais de milho híbrido OC 705, submetidas ao teste de envelhecimento acelerado, à temperatura de 43ºC. Utilizou-se o modelo logístico y(t)=C/(1+exp(B(t-M))) para ajustar os dados. As medidas de viés de Box e de curvaturas paramétrica e intrínseca foram usadas para o diagnóstico do modelo. O modelo proposto ajusta-se adequadamente aos dados de percentuais germinativos de sementes de milho híbrido OC 705, para todos os lotes. Com base nas estimativas dos parâmetros e qualidade de ajuste, o lote três foi identificado como sendo o melhor para comercialização, por apresentar menor redução no poder germinativo ao longo do tempo.

This research was developed with the goal to adjust a nonlinear regression model to estimate seed germination performance of three commercial seed lots of hybrid maize OC 705, subjected to accelerated aging test at a temperature of 43oC. The logistic model y(t)=C/(1+exp (B (t-M))) was used to fit the data. Measures of bias Box and parametric intrinsic bends were used for the diagnosis of the model. The proposed model fits properly to seed germination percentage data of hybrid corn seeds for OC 705, for all seed lots. Based on estimates of the parameters and fit quality, the seed lot three was identified as being the best for marketing, by presenting less reduction in seed germination power over time.

Parameters estimation in the model for in situ degradability of mertens and loften / Estimação dos parâmetros no modelo para degradabilidade in situ de Mertens e Loften

The aim of this study is to evaluate the behavior of the parameters of the degradation model proposed by Mertens & Loften (1980) fitted to the results of a rehearsal of degradability in situ. In the experiment, we evaluate the potentially degradable residue of neutral detergent fiber (NDF) of coastcross grass (Cynodon dactylon x Cynodon nlemfunensis) cut at 60 days, with three replications. The potentially degradable residue of NDF is studied using fifteen incubation times (0; 0.5; 1; 3; 6; 9; 12; 18; 24; 36; 48; 56; 72; 96 and 120 hours). The experimental plot is comprised of a non-lactating cow with a permanent ruminal fistula. It is obtained mean and individual fits for the animals. Variances of parameter estimators is also obtained through both the covariance matrix of the parameters and the jackknife method, then resulting expressions for the estimate of the confidence interval for the parameters of the model. The results shows that the jackknife method presents larger variance estimate for the parameters of the model of Mertens & Loften (1980), resulting in confidence intervals of greater amplitude and less precise parameter estimates for both the individual and mean fits.

Objetiva-se avaliar o comportamento dos parâmetros do modelo de degradação proposto por Mertens & Loften (1980) ajustado aos resultados de um ensaio de degradabilidade in situ. No experimento é avaliado o resíduo potencialmente degradável da fibra em detergente neutro (FDN) da gramínea coastcross (Cynodon dactylon x Cynodon nlemfunensis) cortada aos 60 dias, com três repetições. O resíduo potencialmente degradável da FDN é estudado utilizando quinze tempos de incubação (0; 0,5; 1; 3; 6; 9; 12; 18; 24; 36; 48; 56; 72; 96 e 120 horas). A parcela experimental é constituída por uma vaca não lactante, com fístula ruminal permanente. São obtidos ajustes médios e individuais para os animais. Obtem-se também as variâncias dos estimadores dos parâmetros por meio da matriz de variância e covariância dos parâmetros e pelo método jackknife, propondo-se expressões para a estimação do intervalo de confiança para os parâmetros do modelo. Os resultados mostram que o método de jackknife apresenta maior estimativa de variância para os parâmetros do modelo de Mertens & Loften (1980), resultando em intervalos de confiança de maior amplitude e estimativas dos parâmetros menos precisas, nos ajustes individuais e médios.

Research on the Surface Electromyographic Signal Characteristics in Vastus Medialis during Muscular Fatigue / 中国运动医学杂志

Objective To explore a new method for evaluating muscle fatigue by analyzing the surface electromyographic(SEMG) signal characteristics and to search for the practical use of SEMG.Methods Four healthy young females performed continuous isometric contractions of vastus medialis at 65? knee extension with 60% MVC for 3 minutes. SEMG signals were recorded from bilateral vastus medialis. The data were analyzed through curve fitting and nonlinear regression.Results All the estimative curves for SEMG parameter in relation to the testing phase are of cubic with the equations of Y=b_0+b_1x+b_2x2+b_3x3. The b1 and b3 in the formula are negative and b2 is positive for MF,MPF,ZCR, whereas the b1 and b3 are positive and b2 is negative for AEMG.Conclusion The cubic curve during muscle fatigue suggests that three main factors may involve in muscle fatigue. The factors were discussed briefly and need to be confirmed further.

Nonlinear Regression Analysis of Chief Chemical Components in the Combinations of Different-dose Herbs of Wutou Decoction / 中药新药与临床药理

Objective To observe the changes of chief chemical components(hypaconitine,ephedrine,pseudoephedrine,peoniflorin,glycyrrhetic acid) in the combinations of different-dose herbs of Wutou Decoction(WD). Methods Uniform design method was adopted to design the experiments,and HPLC was applied to determine the contents of chief chemical components of hypaconitine,ephedrine,pseudoephedrine,peoniflorin,glycyrrhetic acid. DPS V7.55 was used to carry out the nonlinear regression analysis of experimental data such as decocting rates of the chief chemical components. The mathematical model was established to analyze the experimental results. Finally,with the decocting rates of the chief chemical components as the optimizing indexes,the combination of optimal-dose herbs of WD was seeked. Results There existed an interaction between each herb of WD,and each herbs as well as the interaction between the herbs had a certain effects on the decocting rate of the chemical components. In particular,the interaction of prepared Radix Aconiti and prepared Radix Glycyrrhizae had obvious effects on the decocting rates of hypaconitine and glycyrrhetic acid. On the basis of the different optimization index,different combinations of optimal-dose herbs of WD can be obtained. Conclusion Through the method of nonlinear regression analysis,rich connotation of compatibility in Chinese herbal formula can be obtained.The optimization of optimal-dose herbs combination of the formula should be based on the pharmacological actions.