RESUMO
We present a thorough analysis of the dynamic behaviour of hybrid atomistic/coarse-grained (CG) models of polymer melts. While structural properties are well preserved in a dual-resolved model, we show how the dynamic of the chains can be influenced by the simultaneous presence of atoms and beads. We show that although the polymer chains are long enough to exhibit reptation, the corresponding CG model is unable to capture the expected subdiffusive regimes and seems to still follow the Rouse dynamics. The introduction of atoms in the chain restores the correct dynamic regime, and the dynamics of hybrid systems becomes comparable to that of the atomistic dynamics as the atoms/beads ratio is increased.
RESUMO
The statistical methods used in occupational health studies were evaluated by analyzing the papers published from 1986 to 1990 in the proceedings of the annual meetings of the Italian Society of Occupational Medicine and Industrial Hygiene, in order to calculate the degree of understanding of the readers provided with only one-sided knowledge of statistical subjects and to improve the educational objectives in postgraduate schools of occupational health. Almost 70% of the 1151 articles reviewed contained some kind of statistical analysis: methods more complicated than descriptive statistics were used in about 35%. Student's t test (15%) and chi square (12%) were the most common methods. Other methods were less frequently used, so that it was possible to estimate that the learning of any new method would improve the understanding of about 1-2% of the articles. A wider use of statistical methods in data analysis is recommended; the attainment of a higher level of statistical knowledge should be a priority target in occupational health training.
