Deformation of doubly oriented polyethylene,nylon 66 and poly(ethylene terephthalate)

Doubly oriented specimens of high density polyethylene (HDPE), nylon 66 and poly(ethylene terephthalate) (PET) were re-stretched along a direction perpendicular to the molecular chain axis at temperatures ranging between room temperature and the respective polymer melting points. Brittle failure was observed for PE samples at all the test temperatures with no significant amount of plastic deformation; whereas, for both PET and nylon 66 samples, ductile deformation was observed at elevated temperatures with plastic strain of >400%. The ductile deformation of nylon 66 and PET occurred with an anisotropic change in the cross-sectional dimensions of the specimen, the reduction taking place predominantly in only one lateral direction. The morphological change accompanying the drawing of the doubly oriented PET and nylon 66 material was examined by using X-ray and optical methods. The implications of the difference in deformation behaviour with respect to the morphological differences among oriented PE, PET and nylon 66 materials are discussed.     

The disk loaded monopole antenna

The method of moments (MoM) is used to analyze the disk loaded monopole (DLM) antenna. Results were validated by comparison with mode-matching and wire-model methods as well as with measurements covering a wide range of electrical sizes. A quasistatic treatment is shown to be both rapid and accurate for the electrically small case. Equivalent circuits are obtained for predicting communication system performance. Parameters defining the fundamental limitations of electrically small antennas are extracted and shown to be accurate for system analysis and useful as design tools.     

Are perinatal risk factors helpful in predicting and optimizing treatment strategies for transient hypothyroxinemia in very-low-birth-weight infants?

Transient hypothyroxinemia is common in premature infants and has been associated with intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), poor neurodevelopmental outcomes, and mortality. Recent trials have failed to show that supplemental thyroid hormone improves overall neurodevelopmental outcome. The objective of this article is too determine perinatal risk factors for transient hypothyroxinemia (TH). We studied a cohort of infants born between July 1993 and July 2000 who were less than 1500 g and who received a newborn screening for thyroid function ( n = 932). Total serum thyroxine (T(4)) was collected routinely on the fifth day of life. T (4) was correlated with gestational age (R = 0.59, p < 0.01). After controlling for potential confounding variables, gestational age, dopamine, and mechanical ventilation were found to be independently associated with low T (4) (overall model: r(2) = 0.41, p < 0.01). Number needed to treat (NNT) analysis showed treating all infants less than 27 weeks would lead to treating 6.3 infants for every one with a subsequent T(4) < 5 microg/dL. By combining gestational age and need for dopamine support, NNT = 2.4 for every one infant with subsequent T(4) < 5 microg/dL. Low gestational age, mechanical ventilation, and need for dopamine were associated with low T(4) levels and may be helpful in optimizing treatment strategies for TH.     

System complexity and integrated diagnostics

An overview of a complete approach to integrated diagnostics is given. The approach is centered around an information-flow model and incorporates techniques from information fusion and artificial intelligence to guide analyses. The concept of integrated diagnosis is explained, and the model is examined. The authors show how to analyze testability, evaluate fault diagnosis, and create maintenance aids