Relationship among diastolic intraventricular pressure gradients, relaxation, and preload: impact of age and fitness.

Item does not contain fulltextDiastolic intraventricular pressure gradients (IVPGs) are a measure of the ability of the ventricle to facilitate its filling using diastolic suction. We assessed 15 healthy young but sedentary subjects, aged 65 yr with known reductions in ventricular compliance (elderly sedentary subjects; age, 70 +/- 4 yr); and 12 master athletes, aged >65 yr, previously shown to have preserved ventricular compliance (elderly fit subjects; age, 68 +/- 3 yr). Pulmonary capillary wedge pressure (PCWP) and echocardiography measurements were performed at baseline, during load manipulation by lower body negative pressure at -15 and -30 mmHg, and after saline infusion of 10 and 20 ml/kg (elderly) or 15 and 30 ml/kg (young). IVPGs were obtained from color M-mode Doppler echocardiograms. Baseline IVPGs were lower (1.2 +/- 0.4 vs. 2.4 +/- 0.7 mmHg, P < 0.0001), and the time constant of pressure decay (tau(0)) was longer (60 +/- 10 vs. 46 +/- 6 ms, P < 0.0001) in elderly sedentary than in young subjects, with no difference in PCWP. Although PCWP changes during load manipulations were similar (P = 0.70), IVPG changes were less prominent in elderly sedentary than in young subjects (P = 0.02). Changes in stroke volume and IVPGs during loading manipulations correlated (r = 0.96, P = 0.0002). PCWP and tau(0) were strong multivariate correlates of IVPGs (P < 0.001, for both). IVPG response to loading interventions in elderly sedentary and elderly fit subjects was similar (P = 0.33), despite known large differences in ventricular compliance. The ability to regulate IVPGs during changes in preload is impaired with aging. Preserving ventricular compliance during aging by lifelong exercise training does not prevent this impairment

Determinação do número ótimo de classificações imperfeitas na avaliação da conformidade de produtos Determination of the optimal number of imperfect classifications in the evaluation of the conformity of products

Neste trabalho estudamos o número ótimo de classificações independentes por unidade produzida supondo que haja dois tipos de erro: o tipo I, no qual classifica-se um produto como não-conforme quando ele na realidade é conforme; e o tipo II, no qual classifica-se um produto como conforme quando na realidade é não-conforme. Desenvolvemos um modelo econômico para minimizar o custo médio total em função dos erros de classificação e do custo de cada classificação. Pela complexidade da função-objetivo associada ao modelo, utilizamos um procedimento exaustivo de busca juntamente com um limitante superior do valor ótimo. Todo o procedimento computacional teve uma implementação relativamente simples e está disponível como uma planilha eletrônica do Excel e um código do software estatístico Minitab.<br>In this study we investigate the optimal number of independent classifications per unit produced when there are two types of classification errors: type I, where product is classified as conforming when it is not in reality, and type II, where product is classified as non-conforming when in reality it is conforming. We developed an economic model to minimize the total medium cost as a function of the classification errors and the cost of each classification. Due to the complexity of the objective function associated to the model, we used an exhaustive procedure with an upper bound of the optimal value. The procedure may be implemented easily and is available either as an Excel spreadsheet or as a macro of the statistical software Minitab