![]() PIRN can now compute two kinds of lower bounds: general bound (using the approach in Wu, ISMB 2010) and tree-child lower bound (which is only applicable to tree-child networks). ![]() ![]() The main feature added is enhancing lower bound computation on the minimum reticulation. Sajad Mirzaei and Yufeng Wu, " Fast Construction of Parsimonious Hybridization Networks for Multiple Phylogenetic Trees", IEEE/ACM Transaction on Computational Biology and Bioinformatics, 2016.Yufeng Wu, "An Algorithm for Constructing Parsimonious Hybridization Networks with Multiple Phylogenetic Trees", in Proceedings of RECOMB 2013.Yufeng Wu, "Close lower and upper bounds for the minimum reticulate network of multiple phylogenetic trees", in Proceedings of ISMB 2010, Bioinformatics 2010 26(12):i140-i148, 2010.The quality of the pirn winding was crucial to the success of day’s weaving and some weavers, being dissatisfied with the winding from their pirn winder, would rewind their pirn’s in an evening to ensure a perfect tension on the shuttle.Parsimonious construction of phylogenetic networks from gene trees ![]() A hand silk weaver would use between 60 to 80 pirn’s in a working day. By increasing the speed of weaving there was an increased demand for more weft, and more weft winding of pirn’s. The pirn stayed fixed on the pin which was sprung loaded to lift upward to enable the changing of empty ones. The pirn needed a tapering away from the far end in order that the weft thread would release and travel along the pirn whilst it unravelled. This heralded the demise of the quill package to make way for the all new ‘pirn’, ‘plug’ or even ‘spool’. With this idea the quill would not be a solution, as the weft would not be wound from a central start but instead from the base to the opposite end. This idea was to completely change the hand shuttle, as the yarn could flow without the restriction of the revolving quill. The skill of the weaver was to cut the quill from the straightest part, so that the natural curvature of the feather spine was kept to a minimum, as this bias could affect the tension on the thread as it unraveled whilst in motion. As the quill was a ready-made tube, they could be cut to fit the shuttle aperture easily and discarded when they became split or dogged at the edges. To hols the quill inside the shuttle there was a hard wire sprung or wooden pin that fitted into a small hole in each end of the shuttle. The curve of the shuttle faced away from the reed, which is used to beat the weft into the cloth. The hand shuttle could be straight and boat like with symmetrical ends or shaped with a curvature, as the path through the shed of the loom was in fact more ark shape than straight. ![]() Early shuttles were thrown across the width of the with the flick of the hand. In order that the weft could be released from the shuttle during weaving, the thread needed to be carefully wound up in preparation. There was another important requirement for the silk weaver and his work as the quill, with the feather flights stripped off, was the ideal ready-made hollow tube for use in the shuttle. The Quill, the Pirn and the Shuttle by Richard Humphries A healthy goose in the 18 th century was more than just for the table or the eiderdown. ![]()
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