Effect of tissue Doppler on the accuracy of novice and expert interpreters of Dobutamine echocardiography

The subjective interpretation of dobutamine echocardiography (DBE) makes the accuracy of this technique dependent on the experience of the observer, and also poses problems of concordance between observers. Myocardial tissue Doppler velocity (MDV) may offer a quantitative technique for identification of coronary artery disease, but it is unclear whether this parameter could improve the results of less expert readers and in segments with low interobserver concordance. The aim of this study was to find whether MDV improved the accuracy of wall motion scoring in novice readers, experienced echocardiographers, and experts in stress echocardiography, and to identify the optimal means of integrating these tissue Doppler data in 77 patients who underwent DBE and angiography. New or worsening abnormalities were identified as ischemia and abnormalities seen at rest as scarring. Segmental MDV was measured independently and previously derived cutoffs were applied to categorize segments as normal or ab normal. Five strategies were used to combine MDV and wall motion score, and the results of each reader using each strategy were compared with quantitative coronary angiography. The accuracy of wall motion scoring by novice (68 +/- 3%) and experienced echocardiographers (71 +/- 3%) was less than experts in stress echocardiography (88 +/- 3%, p < 0.001). Various strategies for integration with MDV significantly improved the accuracy of wall motion scoring by novices from 75 +/- 2% to 77 +/- 5% (p < 0.01). Among the experienced group, accuracy improved from 74 +/- 2% to 77 +/- 5% (p < 0.05), but in the experts, no improvement was seen from their baseline accuracy. Integration with MDV also improved discordance related to the basal segments. Thus, use of MDV in all segments or MDV in all segments with wall motion scoring in the apex offers an improvement in sensitivity and accuracy with minimal compromise in specificity. (C) 2001 by Excerpta Medica, Inc

Phylogenetic tree reconstruction with protein linkage

LNCS v. 7292 is Proceedings of the 8th International Symposium on Bioinformatics Research and Applications, ISBRA 2012When reconstructing a phylogenetic tree, one common representation for a species is a binary string indicating the existence of some selected genes/proteins. Up until now, all existing methods have assumed the existence of these genes/proteins to be independent. However, in most cases, this assumption is not valid. In this paper, we consider the reconstruction problem by taking into account the dependency of proteins, i.e. protein linkage. We assume that the tree structure and leaf sequences are given, so we need only to find an optimal assignment to the ancestral nodes. We prove that the Phylogenetic Tree Reconstruction with Protein Linkage (PTRPL) problem for three different versions of linkage distance is NP-complete. We provide an efficient dynamic programming algorithm to solve the general problem in O(4 m •n)4 and O(4 m •(m + n)) time (compared to the straight-forward O(4 m •m •n) and O(4 m •m 2 •n) time algorithm), depending on the versions of linkage distance used, where .. stands for the number of species and .. for the number of proteins, i.e. length of binary string. We also argue, by experiments, that trees with higher accuracy can be constructed by using linkage information than by using only hamming distance to measure the differences between the binary strings, thus validating the significance of linkage information. © 2012 Springer-Verlag.link_to_subscribed_fulltex

High electron mobility InN

Irradiation of InN films with 2 MeV He+ ions followed by thermal annealing below 500 °C creates films with high electron concentrations and mobilities, as well as strong photoluminescence. Calculations show that electron mobility in irradiated samples is limited by triply charged donor defects. Subsequent thermal annealing removes a fraction of the defects, decreasing the electron concentration. There is a large increase in electron mobility upon annealing; the mobilities approach those of the as-grown films, which have 10 to 100 times smaller electron concentrations. Spatial ordering of the triply charged defects is suggested to cause the unusual increase in electron mobility