| 1. |
- Ballesteros, Miguel, et al.
(författare)
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Going to the Roots of Dependency Parsing
- 2013
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Ingår i: Computational linguistics - Association for Computational Linguistics (Print). - : MIT Press. - 0891-2017 .- 1530-9312. ; 39:1, s. 5-13
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Tidskriftsartikel (refereegranskat)abstract
- Dependency trees used in syntactic parsing often include a root node representing a dummy word prefixed or suffixed to the sentence, a device that is generally considered a mere technical convenience and is tacitly assumed to have no impact on empirical results. We demonstrate that this assumption is false and that the accuracy of data-driven dependency parsers can in fact be sensitive to the existence and placement of the dummy root node. In particular, we show that a greedy, left-to-right, arc-eager transition-based parser consistently performs worse when the dummy root node is placed at the beginning of the sentence (following the current convention in data-driven dependency parsing) than when it is placed at the end or omitted completely. Control experiments with an arc-standard transition-based parser and an arc-factored graph-based parser reveal no consistent preferences but nevertheless exhibit considerable variation in results depending on root placement. We conclude that the treatment of dummy root nodes in data-driven dependency parsing is an underestimated source of variation in experiments and may also be a parameter worth tuning for some parsers.
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| 2. |
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| 3. |
- Mate, Diana, et al.
(författare)
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Switching from blue to yellow : altering the spectral properties of a high redox potential laccase by directed evolution
- 2013
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Ingår i: Biocatalysis and Biotransformation. - : Informa Healthcare. - 1024-2422 .- 1029-2446. ; 31:1, s. 8-21
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Tidskriftsartikel (refereegranskat)abstract
- During directed evolution to functionally express the high redox potential laccase from the PM1 basidiomycete in Saccharomyces cerevisiae, the characteristic max. absorption at the T1 copper site (Abs610T1Cu) was quenched, switching the typical blue color of the enzyme to yellow. To det. the mol. basis of this color change, we characterized the original wild-type laccase and its evolved mutant. Peptide printing and MALDI-TOF anal. confirmed the absence of contaminating protein traces that could mask the Abs610T1Cu, while conservation of the redox potential at the T1 site was demonstrated by spectroelectrochem. redox titrns. Both wild-type and evolved laccases were capable of oxidizing a broad range of substrates (ABTS, guaiacol, DMP, synapic acid) and they displayed similar catalytic efficiencies. The laccase mutant could only oxidize high redox potential dyes (Poly R-478, Reactive Black 5, Azure B) in the presence of exogenous mediators, indicating that the yellow enzyme behaves like a blue laccase. The main consequence of over-expressing the mutant laccase was the generation of a six-residue N-terminal acidic extension, which was assocd. with the failure of the STE13 protease in the Golgi compartment giving rise to alternative processing. Removal of the N-terminal tail had a neg. effect on laccase stability, secretion and its kinetics, although the truncated mutant remained yellow. The results of CD spectra anal. suggested that polyproline helixes were formed during the directed evolution altering spectral properties. Moreover, introducing the A461T and S426N mutations in the T1 environment during the first cycles of lab. evolution appeared to mediate the alterations to Abs610T1Cu by affecting its coordinating sphere. This laccase mutant is a valuable departure point for further protein engineering towards different fates.
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| 4. |
- Nivre, Joakim, 1962-, et al.
(författare)
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MaltOptimizer: A System for MaltParser Optimization.
- 2012
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Ingår i: Proceedings of the Eighth International Conference on Language Resources and Evaluation (LREC). - : European Language Resources Association. - 9782951740877
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Konferensbidrag (refereegranskat)
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| 5. |
- Nivre, Joakim, 1962-, et al.
(författare)
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MaltOptimizer: An Optimization Tool for MaltParser
- 2012
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Ingår i: Proceedings of the Demonstrations at the 13th Conference of the European Chapter of the Association for Computational Linguistics (EACL). - : Association for Computational Linguistics. - 9781937284190 ; , s. 58-62
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Konferensbidrag (refereegranskat)
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