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Modelo de mistura padrão de longa duração com censura uniforme-exponencial
(Universidade Federal de São Carlos, 2010-03-25) Chaves, Josenildo de Souza; Rodrigues, Josemar; https://lattes.cnpq.br/4359114733394761; https://lattes.cnpq.br/5748689441032603
In survival data analysis it is common the occurrence of a large number of individuals to the right. This fact can indicate that, in a fraction of the individuals the event of interest will never happen, in other words, a fraction of individuals of the population is cured or immune. This case is not usually taken into account by the usual survival theory that, in general, considers that the individuals at risk will not achieve cure during the follow-up period. Therefore, the survival models with cure fraction, or long-term survival models, have received a lot of attention in recent years. We consider the exponential distribution for the survival time of individuals at risk and the uniform-exponential distribution for the censoring time. In many situations, it is evident that the censoring mechanism is informative. Lagakos & Williams (1978) proposed a class of models where the acting of the censoring mechanism in the survival time is evaluated and Lagakos (1979) presented several situations in which the assumption of noninformative censoring is violated. The main purpose of this work is to verify the impact of informative uniform-exponential censoring in the survival data analysis under the standard mixture model.
Produção de ácido clavulânico por Streptomyces clavuligerus em cultivos em batelada e batelada alimentada com pulsos de glicerol sob diferentes condições de temperatura
(Universidade Federal de São Carlos, 2010-03-25) Costa, Cecília Ladeira Lopes; Badino Júnior, Alberto Colli; https://lattes.cnpq.br/8903118201027369
The production of enzymes β-lactamases by pathogenic bacteria is the most common mechanism of resistance to β-lactam antibiotics. The β-lactamases catalyze the hydrolysis of β-lactam ring, splitting the amide bond, as a result, the antibiotics become ineffective. Clavulanic acid (CA) is a secondary metabolite β-lactam produced during the fermentation of Streptomyces clavuligerus and has a potent inhibitory activity of β-lactamases. Like other β-lactam compounds, CA is chemically unstable under high temperature conditions. The decomposition of the AC during the bacterial fermentation reduces its concentration in the broth which results in low yields of the process. In this study the production of CA was evaluated in batch processes and batch with glycerol pulses at different temperature conditions in shaker operated at 250 rpm and pH 6.8. Initially, three batch cultures containing glycerol as carbon source were performed at temperatures of 30, 25 and 20ºC. Batch cultivation at 30°C was considered as a control run. Then, other three batch tests were performed with reduction of temperature of 30°C for 25 or 20°C after the exhaustion of glycerol in the broth culture. Added, also were performed four cultures with reduction of temperature associated with feeding of glycerol (1, 2, 3 and 4 pulses of glycerol), resulting in twelve cultures. In general, the production of CA increased with decreasing temperature and feeding of glycerol was beneficial for CA production. For all experiments under low temperatures, the maximum production (CCA-max) and productivity in CC (PCA-max in mg.L-1.h-1) were higher than the control run. In addition, a significant increase product (CA) yield coefficient in relation to the glycerol consumption (YCA/G, mg.g-1) reaching 59.3 mg.g-1 for the batch culture at 20°C, while for the control run was obtained 10.2 mg.g-1. The CCA-max obtained was 1115.6 mg L-1 in cultivation with temperature reduction from 30 to 25°C and three pulses of glycerol, which represented about 7 times the yield on the run control culture at 30°C. The CA degradation in fermentation broth at temperatures of 30, 25 and 20ºC was also evaluated in this study. Values of constant degradation of CA (kdCA) were obtained in different cultivation times. The highest kdCA value in the broth was obtained at 30°C, 0.01306 h-1, and values for 25 and 20ºC were statistically similar, 0.00303 and 0.00173 h-1. The higher rate of production of CA (rCA) of 10.9 mg.L-1.h-1 was observed at 25°C. The results obtained demonstrate the potential application of temperature manipulation during S. clavuligerus fermentation for the optimization of CA production process.
'Cinco prefácios para cinco livros não escritos' de Friedrich Nietzsche: distanciamento em relação a Richard Wagner
(Universidade Federal de São Carlos, 2010-03-25) Hasunuma, Renato Fabrete; Fonseca, Thelma Silveira da Mota Lessa da; https://lattes.cnpq.br/5963148137119518
Friedrich Nietzsche s text Five prefaces to five not-written books (concluded in December 1872) can be read as a document attesting a reserve that would grow stronger between the philosopher Friedrich Nietzsche and the composer Richard Wagner. That reserve would culminate in the subsequent rupture with the close relationship that both of them had cultivated at the time of the composition of Nietzsche s first book, The Birth of Tragedy (concluded in December 1871). The interest of the Five prefaces to five not-written books consists on the fact that, although being considered as belonging to the initial phase of Nietzsche s production, this text already gives signs of many themes that Nietzsche would develop in his search of his own philosophy, which his second book, Human, all too human (published in 1878) is already a product. The prefaces raise a discussion concerning a very characteristic trace of Nietzsche s philosophy that appears here for the first time: the fragmentary character and the intentional incompleteness of his work. Thus, one of the main purposes of this research consists on the conceptual prove, through the investigation of the published works and the posthumous fragments, of the remark of Nietzsche s quest of his own philosophy and how the rupture with Richard Wagner, from the biographical perspective, could have meant to it.