University of Paderborn

About: University of Paderborn is a education organization based out in Paderborn, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Control reconfiguration & Software. The organization has 6684 authors who have published 16929 publications receiving 323154 citations.

Raman scattering efficiency in LiTaO 3 and LiNbO 3 crystals

Abstract: ${\mathrm{LiTaO}}_{3}$ and ${\mathrm{LiNbO}}_{3}$ crystals are investigated here in a combined experimental and theoretical study that uses Raman spectroscopy in a complete set of scattering geometries and corresponding density-functional theory calculations to provide microscopic information on their vibrational properties. The Raman scattering efficiency is computed from first principles in order to univocally assign the measured Raman peaks to the calculated eigenvectors. Measured and calculated Raman spectra are shown to be in qualitative agreement and confirm the mode assignment by Margueron et al. [J. Appl. Phys. 111, 104105 (2012)], thus finally settling a long debate. While the two crystals show rather similar vibrational properties overall, the ${\text{E-TO}}_{9}$ mode is markedly different in the two oxides. The deviations are explained by a different anion-cation bond type in ${\mathrm{LiTaO}}_{3}$ and ${\mathrm{LiNbO}}_{3}$ crystals.

11-cis-retinal protonated Schiff base: influence of the protein environment on the geometry of the rhodopsin chromophore.

Abstract: Density functional theory (DFT) calculations based on the self-consistent-charge tight-binding approximation have been performed to study the influence of the protein pocket on the 3-dimensional structure of the 11-cis-retinal Schiff base (SB) chromophore. Starting with an effectively planar chromophore embedded in a protein pocket consisting of the 27 next-nearest amino acids, the relaxed chromophore geometry resulting from energy optimization and molecular dynamics (MD) simulations has yielded novel insights with respect to the following questions: (i) The conformation of the beta-ionone ring. The protein pocket tolerates both conformations, 6-s-cis and 6-s-trans, with a total energy difference of 0.7 kcal/mol in favor of the former. Of the two possible 6-s-cis conformations, the one with a negative twist angle (optimized value: -35 degrees ) is strongly favored, by 3.6 kcal/mol, relative to the one in which the dihedral is positive. (ii) Out-of-plane twist of the chromophore. The environment induces a nonplanar helical deformation of the chromophore, with the distortions concentrated in the central region of the chromophore, from C10 to C13. The dihedral angle between the planes formed by the bonds from C7 to C10 and from C13 to C15 is 42 degrees. (iii) The absolute configuration of the chromophore. The dihedral angle about the C12-C13 bond is +170 degrees from planar s-cis, which imparts a positive helicity on the chromophore, in agreement with earlier considerations based on theoretical and spectroscopic evidence.

GERBIL – Benchmarking Named Entity Recognition and Linking consistently

Abstract: The ability to compare frameworks from the same domain is of central importance for their introduction into complex applications. In the domains of named entity recognition and entity linking, the large number of systems and their orthogonal evaluation w.r.t. measures and datasets has led to an unclear landscape pertaining to the abilities and weaknesses of the different frameworks. We present GERBIL—an improved platform for repeatable, storable and citable semantic annotation experiments— and how we extended it since its release. With GERBIL, we narrowed this evaluation gap by generating concise, archivable, humanand machine-readable experiments, analytics and diagnostics. The rationale behind our framework is to provide developers, end users and researchers with easy-to-use interfaces that allow for the agile, fine-grained and uniform evaluation of annotation tools on multiple datasets. By these means, we aim to ensure that both tool developers and end users can derive meaningful insights pertaining to the extension, integration and use of annotation applications. In particular, GERBIL provides comparable results to tool developers so as to allow them to easily discover the strengths and weaknesses of their implementations with respect to the state of the art. With the permanent experiment URIs provided by our framework, we ensure the reproducibility and archiving of evaluation results. Moreover, the framework generates data in machine-processable format, allowing for the efficient querying and post-processing of evaluation results. Additionally, the tool diagnostics provided by GERBIL allows deriving insights pertaining to the areas in which tools should be further refined, thus allowing developers to create an informed agenda for extensions and end users to detect the right tools for their purposes. Finally, we implemented additional types of experiments including entity typing. GERBIL aims to become a focal point for the state of the art, driving the research agenda of the community by presenting comparable objective evaluation results. Furthermore, we tackle the central problem of the evaluation of entity linking, i.e., we answer the question how an evaluation algorithm can compare two URIs to each other without being bound to a specific knowledge base. Our approach to this problem opens a way to address the deprecation of URIs of existing gold standards for named entity recognition and entity linking, a feature which is currently not supported by the state of the art. We derived the importance of this feature from usage and dataset requirements collected from the GERBIL user community, which has already carried out more than 24.000 single evaluations using our framework. Through the resulting updates, GERBIL now supports 8 tasks, 46 datasets and 20 systems.