The M/M/n + G queueing model can be used to describe the behavior of a Call Center. This model has Poisson arrivals with rate λ, service times are exponentially distributed with rate µ, n agents and the client´s patience time has general distribution. The waiting in line could not exceed a time (patience) which has distribution G, and if it occurs, the client leaves the system. In this models, Mandelbaum and Zeltyn [2004] showed that there is a linear relationship between average waiting time in queue and the probability of abandonment if the distribution of patience is Exponencial. In this work, we study this relationship in the case of patience with mixed distribution (which has discret and continuous parts). Through mixed distributions we try to represent the user´s reaction to recorded messages reproduced periodically when they are waiting for service. We have used Mixed Exponencial and Mixed Uniform distributions and, in both of them, there is not a linear relationship between average waiting time in queue and the probability of abandonment. We observe that for the same arrival rate, the average waiting time in line for mixed distribution is smaller than Exponencial or Uniform distributions with the same parameters. Also, we study the effect on waiting time and abandonment of different distributions of service and we observe that it is more affected by the coefficient of variation and average that by the particular distribution chosen for service.

A pesquisa trata de exposições ocupacionais por material biológico a que foram submetidos os profissionais de saúde, no Hospital Santa Casa de Misericórdia de Pelotas, no período de janeiro de 2004 a junho de 2008. Trata-se de um estudo transversal, descritivo, com abordagem quantitativa. Utilizou-se como instrumento de pesquisa um questionário elaborado com base na ficha de notificação de acidente de trabalho da referida instituição. Os dados foram digitados e analisados no programa Epi-info 6.04. Como principal resultado encontrou-se a maior ocorrência de acidentes de trabalho com material biológico entre os profissionais técnicos em enfermagem do sexo feminino (38,6%), com idade de 21 a 30 anos (53,9%). A maioria dos acidentes aconteceu através de lesões com perfurocortantes (82,2%), sendo 24,1% no Centro Cirúrgico e 84,5% envolvendo sangue. Conclui-se que o estudo é de extrema relevância, pois, com base no reconhecimento do tipo de acidentes mais frequentes, pode-se conhecer os riscos existentes e intervir na sua redução, por meio de ações preventivas que beneficiem o trabalhador e a instituição.

Tea presents a diverse phenolic composition which is responsible for its alleged biological activities, including the in vivo and in vitro antioxidant capacity. It is very usual to find researches applying statistical methods, such as analysis of variances (ANOVA) and linear Pearson correlation coefficients to analyze the strength of correlation between phenolic composition and the in vitro antioxidant activity of teas from Camellia sinensis (green, black, white, oolong, red, and yellow teas) and Ilex paraguariensis (Yerba-mate), which are the most produced and consumed types of teas. However, evidence has shown that these approaches are not as suitable as multivariate statistical methods once they do not depict nor show association among all results and variables simultaneously, making it difficult to understand clearly the data structure and patterns. Then, the objective of this work is to review and explain some univariate/bivariate and multivariate statistical techniques used to assess the association between phenolic compounds and the in vitro antioxidant activity of green, white, black, red, yellow, oolong and Yerba-mate teas. Moreover, this paper provides an overview on some assays used to estimate the in vitro antioxidant capacity of teas.

Chemometric techniques were used to assess the quality of 51 commercial Brazilian sugarcane spirits (cachaça) based on chemical markers. Benzo(a)pyrene, methanol, 2,3-methyl-1-butanol, acetaldehyde, isobutyl alcohol, npropanol, density, alcoholic strength, and higher alcohols were quantified using chromatographic methods and results were subjected to Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), and Linear Discriminant Analysis (LDA). No significant differences (p ≥ 0.071) were observed in the chemical markers of Brazilian aged and non-aged cachaça samples. Besides non-significant (p = 0.922), the content of benzo(a) pyrene in aged sugarcane spirits was 1.83 times higher than in non-aged ones. Differences in alcoholic strength (p = 0.001) and n-propanol (p = 0.015) were observed among cachaças produced by double distilling, alembic and in stainless steel columns. PCA was not suitable to separate the samples according to the provenance, aging and distilling process, while HCA was effective in separating alembic cachaças produced by from two distinct producing regions. LDA seemed to be very suitable to assess not only the provenance but also the distilling and aging processes that cachaça undergoes, yielding about 91% accuracy to discriminate non-aged from aged cachaça, 81.82% and 86.61% accuracy to discriminate samples from Minas Gerais and São Paulo, respectively.

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Introduction: The antibodies have an important role in the serodiagnosis, constituting the most widely used biomarkers to detect and confirm various diseases. Objective: To investigate the reproducibility of anti-human immunodeficiency virus (HIV) antibodies reactivity, to assess the stability of the sera samples stored at -20ºC for two to eighteen years. Method: Sera were collected in the period 1988-2004 for routine anti-HIV antibodies diagnostic testing. The remaining samples stored at -20ºC, were analyzed in this study. Serum sample stability was assessed by enzyme-linked immunosorbent assay/enzyme immunoassay (ELISA/EIA), indirect immunofluorescence assay (IFA), and Western blot (WB) for detecting anti-HIV antibodies. The previously found results (1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004) and those obtained in 2006 were subjected to Kappa index analysis. Result: In the period 1988-to 2004, the degree of concordance of the ELISA/EIA, IFA and WB results were considered, good (k = 0.80), regular (k = 0.35), and good (k = 0.63), respectively. Conclusion: Regarding HIV serologic test, the serum samples were stable for 18 years in ELISA/EIA and for 4 years in IFA technique, however, for the WB methodology it was not possible to determine the time of stability of the anti-HIV antibodies.

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Este trabalho descreve o desenvolvimento, a validação e a aplicação de planilhas eletrônicas no software Microsoft Excel® para avaliar a qualidade analítica de gráficos de calibração de funções lineares e homoscedásticas, que são usados em análises físico-químicas de águas por espectrofotometria UV-Vis, e obtidos segundo as normas ISO e recomendações IUPAC. Por meio da inserção dos valores de absorbância, as planilhas apresentam os gráficos de calibração e de resíduos e calculam desvio-padrão residual, desviopadrão para coeficiente angular, desvio-padrão para intercepto e coeficiente de determinação. Em termos de predições, as planilhas calculam, com 95 % de confiança, o intervalo de predição (apresentado com a respectiva curva com limites superior e inferior), o valor crítico da absorbância, o valor crítico da concentração (x C ), o valor mínimo detectável da concentração (x D ) ou limite de detecção, o limite de quantificação e os intervalos de confiança para amostras. De uma planilha inicial, simplificações foram introduzidas e as planilhas resultantes foram usadas nas análises de nitrato, nitrito e ferro. A influência das simplificações no cálculo dos parâmetros, nas relações entre os parâmetros x C /x D da ISO 11843-1,2 e nos parâmetros da Comissão Europeia CCα (limite de decisão)/CCβ (capacidade de detecção), são discutidas. Palavras-chave. controle de qualidade analítica, curvas analíticas, análise da água, planilhas eletrônicas.