1,721,072 research outputs found
A comparative evaluation of nonlinear dynamics methods for time series prediction
Full text linkA key problem in time series prediction using autoregressive models is to fix the model order, namely the number of past samples required to model the time series adequately. The estimation of the model order using cross-validation may be a long process. In this paper, we investigate alternative methods to cross-validation, based on nonlinear dynamics methods, namely Grassberger-Procaccia, K,gl, Levina-Bickel and False Nearest Neighbors algorithms. The experiments have been performed in two different ways. In the first case, the model order has been used to carry out the prediction, performed by a SVM for regression on three real data time series showing that nonlinear dynamics methods have performances very close to the cross-validation ones. In the second case, we have tested the accuracy of nonlinear dynamics methods in predicting the known model order of synthetic time series. In this case, most of the methods have yielded a correct estimate and when the estimate was not correct, the value was very close to the real one
Chronic lung disease after premature birth
Full text linkChronic lung disease can no longer be considered only a pediatric disease. For some infants born prematurely, especially those with bronchopulmonary dysplasia, substantial obstructive lung disease persists into adolescence and young adulthood. This pulmonary derangement remains latent in most people, but a reduced respiratory reserve could increase the risk of a COPD-like phenotype later in life. Advances in neonatal care have increased survival after preterm birth. Because many of these survivors are now approaching adulthood, family doctors and chest physicians will be seeing more cases of this novel chronic pulmonary disease, which begins in neonatal life.
The pathogenesis of bronchopulmonary dysplasia is still elusive, and its treatment is empirical. Tools should be developed for phenotype-specific diagnosis and management of chronic lung disease. Long-term surveillance studies will be needed if we are to better understand the natural history of chronic lung disease after premature birt
The term "asthma" should be avoided in describing the chronic pulmonary disease of prematurity.
No full textBronchopulmonary dysplasia: Definitions and long-term respiratory outcome
No full textBronchopulmonary dysplasia (BPD) is a chronic respiratory disease that develops as a consequence of perinatal/neonatal lung injury, and it is one of the most important sequelae of premature birth. In this article we discuss recent changes in the definition of BPD, the main differences between the old and the new form and we summarize recent data on long-term respiratory outcome. The diagnosis of BPD is currently based on the need for supplemental oxygen for at least 28 days after birth, and its severity is graded according to the respiratory support required at 36 postmenstrual weeks. The "new BPD" is mainly a developmental disorder in which the immature lung fails to reach its full structural complexity. Longitudinal studies on children with BPD identified, at all ages, a greater need to use inhaled asthma medication and a significant airflow obstruction. Whether survivors of BPD and prematurity have a risk of developing a COPD-like phenotype with aging is a question that only lung function studies extended to middle-age and beyond will answer
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