Aplicações da função logarítmica em sala de aula no ensino médio: uma proposta de solução de problemas pela transposição para a linguagem matemática

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

On the Generalized Mittag-Leffler Function and its Application in a Fractional Telegraph Equation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Temporal variability of soil CO2 emission after conventional and reduced tillage described by an exponential decay in time model

A quantificação do impacto das práticas de preparo sobre as perdas de carbono do solo é dependente da habilidade de se descrever a variabilidade temporal da emissão de CO2 do solo após preparo. Tem sido sugerido que as grandes quantidades de CO2 emitido após o preparo do solo podem servir como um indicador das modificações nos estoques de carbono do solo em longo termo. Neste trabalho é apresentado um modelo de duas partes baseado na temperatura e na umidade do solo e que inclui um termo exponencial decrescente do tempo que é eficiente no ajuste das emissões intermediárias após preparo: arado de disco seguido de uma passagem com a grade niveladora (convencional) e escarificador de arrasto seguido da passagem com rolo destorroador (reduzido). As emissões após o preparo do solo são descritas utilizando-se estimativa não linear com um coeficiente de determinação (R²) tão alto quanto 0.98 após preparo reduzido. Os resultados indicam que nas previsões da emissão de CO2 após o preparo do solo é importante considerar um termo exponencial decrescente no tempo após preparo.

The Poisson-exponential regression model under different latent activation schemes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Does the Choice of the Halogenated Anesthetic Influence Renal Function during Hemorrhagic Shock and Resuscitation?

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of high-dose fentanyl on renal function in dogs

OBJETIVOS: Estudamos os efeitos de alta dose de fentanil (F) em atributos de função renal (FR) do cão. DESENHO: Anestesiamos com pentobarbital sódico (PS) 16 cães divididos aleatoriamente em 2 grupos: manutenção com PS (Gi) e PS com F (0,05 mg.kg-1) (G2). INTERVENÇÃO: os cães foram ventilados artificialmente e tiveram cateterizadas as veias femorais esquerda e direita e a artéria femoral esquerda para infusão de drogas e coleta de dados hemodinâmicos e de sangue para dosagens laboratoriais. Coletou-se urina durante todo experimento. MENSURAÇÃO: Determinaram-se os valores de atributos de FR.. RESULTADOS: PS não mudou a FR e o comportamento de G1 deveu-se à expansão do volume extracelular. O F diminuiu significativamente freqüência cardíaca, pressão arterial média, clearance de creatinina, volume urinário, clearance osmolar e excreção fracionária de sódio e potássio. CONCLUSÕES: A diminuição da FR foi provavelmente devida às alterações hemodinâmicas induzidas pelo F, não se descartando possível ação da aldosterona.

Direct effects of colchicine on myocardial function - Studies in hypertrophied and failing spontaneously hypertensive rats

The aging spontaneously hypertensive rat (SHR) is a model in which the transition from chronic stable left ventricular hypertrophy to overt heart failure can be observed. Although the mechanisms for impaired function in hypertrophied and failing cardiac muscle from the SHR have been studied, none accounts fully for the myocardial contractile abnormalities. The cardiac cytoskeleton has been implicated as a possible cause for myocardial dysfunction. If an increase in microtubules contributes to dysfunction, then myocardial microtubule disruption by colchicine should promote an improvement in cardiac performance. We studied the active and passive properties of isolated left ventricular papillary muscles from 18- to 24-month-old SHR with evidence of heart failure (SHR-F, n=6), age-matched SHR without heart failure (SHR-NF, n=6), and age-matched normotensive Wistar-Kyoto rats (WKY, n=5). Mechanical parameters were analyzed before and up to 90 minutes after the addition of colchicine (10(-5), 10(-4), and 10(-3) mol/L). In the baseline state, active tension (AT) developed by papillary muscles from the WKY group was greater than for SHR-NF and SHR-F groups (WKY 5.69+/-1.47 g/mm(2) [mean+/-SD], SHR-NF 3.41+/-1.05, SHR-F 2.87+/-0.26; SHR-NF and SHR-F P<0.05 versus WKY rats). The passive stiffness was greater in SHR-F than in the WKY and SHR-NF groups (central segment exponential stiffness constant, K-cs: SHR-F 70+/-25, SHR-NF 44+/-17, WKY 41+/-13 [mean+/-SD]; SHR-F P<0.05 versus; SHR-NF and WKY rats). AT did not improve after 10, 20, and 30 minutes of exposure to colchicine (10(-5), 10(-4), and 10(-3) mol/L) in any group. In the SHR-F group, AT and passive stiffness did not change after 30 to 90 minutes of colchicine exposure (10(-4) mol/L). In summary, the data in this study fail to demonstrate improvement of intrinsic muscle function in SHR with heart failure after colchicine. Thus, in the SHR there is no evidence that colchicine-induced cardiac microtubular depolymerization affects the active or passive properties of hypertrophied or failing left ventricular myocardium.

Follow-up study of morphology and cardiac function in rats undergoing induction of supravalvular aortic stenosis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Stretched-exponential behavior and random walks on diluted hypercubic lattices

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Rheological properties of frozen concentrated orange juice (FCOJ) as a function of concentration and subzero temperatures

Data on flow properties of Frozen Concentrated Orange Juice (FCOJ) produced from oranges cv. Pera-Rio (65.04 Brix, 8.8% w/w pulp content, 2.5% w/w pectin, 3.84% citric acid, 1.293 g cm(-3)) from -18 to 0 degrees C were fitted with appropriate predictive models. The power law model was found to be the most appropriate to fit the flow curves obtained for FCOJ between 46.56 and 65.04 degrees Brix. In higher concentrations, thixotropy was observed and showed more temperature dependence. A single equation combining Arrhenius and exponential relationships was applied to describe the temperature effect and shear rate on the quantity of breakdown of FCOJ.

Improved systolic ventricular function with normal myocardial mechanics in compensated cardiac hypertrophy

There is still controversy about the relation between changes in myocardial contractile function and global left ventricular (LV) performance during stable concentric hypertrophy. To clarify this, we analyzed LV function in vivo and myocardial mechanics in vitro in rats with pressure overload-induced cardiac hypertrophy. Male Wistar rats (70 g) Underwent ascending aortic stenosis for 8 weeks (group AAS, n = 9). LV performance wits assessed by transthoracic echocardiography Under anesthesia. Myocardial function Was studied in isolated papillary muscle preparations during isometric contraction. The data were compared with age- and sex-matched sham-operated rats (group C, 11 = 9). LV weight-to-body weight ratio (C: 2.13 +/- 0.14 mg/g; AAS: 3.24 +/- 0.44) LV relative wall thickness (C: 0.18 +/- 0.02; AAS: 0.33 +/- 0.09), and LV fractional shortening (C: 54 +/- 5%; AAS: 70 +/- 8%) were increased in group AAS (P<0.05). Echocardio-graphic analysis also indicated a significant association (r = 0.74 P<0.001) between the percent fractional shortening index and LV relative wall thickness. The performance of AAS isolated In muscle revealed that active tension (C: 6.6 +/- 1.7 g/mm(2); AAS: 6.5 +/- 1.5 g/mm(2)) and maximum rate of tension development (C: 69 +/- 21 g/mm(2)/s AAS: 69 +/- 18 g/mm(2)/s) were not significantly different Front group C (P>0.05). In conclusion, compensated pressure-overload myocardial hypertrophy is associated with preserved myocardial function and increased ventricular performance. The improved LV function might be due to the ventricular remodeling, characterized by an increased relative wall thickness.

The complementary exponential power lifetime model

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Poisson-exponential distribution: a Bayesian approach

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Improved systolic ventricular function with normal myocardial mechanics in compensated cardiac hypertrophy

There still controversy about the relation between changes in myocardial contractile function and global left ventricular (LV) performance during stable concentric hypertrophy. To clarify this, we analyzed LV function in vivo and myocardial mechanics in vitro in rats with pressure overload-induced cardiac hypertrophy. Male Wistar rats (70 g) underwent ascending aorta stenosis for 8 weeks (group AAS, n=9). LV performance was assessed by transthoracic echocardiography under light anesthesia. Myocardial function was studied in isolated papillary muscle preparation during isometric contraction. The data were compared with age- and sex-matched sham-operated rats (group C, n=9). LV weight-to-body weight ratio (C: 2.0 ± 0.5 mg/g; AAS: 3.3 ± 0.7 mg/g), LV relative wall thickness (C: 0.19 ± 0.02; AAS; 0.34 ± 0.10), and LV fractional shortening (C: 54 ± 5%; AAS: 70 ± 8%) were increased in the group AAS (p<0.05). Echocardiographic analysis also indicated a significant association (r=0.74; p<0.001) between percent fractional shortening and LV relative wall thickness. The performance of AAS isolated muscle revealed that active tension (C: 6.6 ± 1.7 g/mm 2; AAS: 6.5 ± 1.5 g/mm 2) and maximum rate of tension development (C: 69 ± 21 g/mm 2/s; AAS: 69 ± 18 g/mm 2) were not significantly different from group C (p>0.05). In conclusion: 1) Compensated pressure-overload myocardial hypertrophy is associated with preserved myocardial function and increased ventricular performance; 2) The improved LV function might be due to the ventricular remodeling characterized by an increased relative wall thickness. Copyright © 2002 By PJD Publications Limited.

The Poisson-exponential lifetime distribution

In this paper we proposed a new two-parameters lifetime distribution with increasing failure rate. The new distribution arises on a latent complementary risk problem base. The properties of the proposed distribution are discussed, including a formal proof of its probability density function and explicit algebraic formulae for its reliability and failure rate functions, quantiles and moments, including the mean and variance. A simple EM-type algorithm for iteratively computing maximum likelihood estimates is presented. The Fisher information matrix is derived analytically in order to obtaining the asymptotic covariance matrix. The methodology is illustrated on a real data set. © 2010 Elsevier B.V. All rights reserved.