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    Simulation of the future sea level contribution of Greenland with a new glacial system model
    (Katlenburg-Lindau : Copernicus, 2018) Calov, Reinhard; Beyer, Sebastian; Greve, Ralf; Beckmann, Johanna; Willeit, Matteo; Kleiner, Thomas; Rückamp, Martin; Humbert, Angelika; Ganopolski, Andrey
    We introduce the coupled model of the Greenland glacial system IGLOO 1.0, including the polythermal ice sheet model SICOPOLIS (version 3.3) with hybrid dynamics, the model of basal hydrology HYDRO and a parameterization of submarine melt for marine-terminated outlet glaciers. The aim of this glacial system model is to gain a better understanding of the processes important for the future contribution of the Greenland ice sheet to sea level rise under future climate change scenarios. The ice sheet is initialized via a relaxation towards observed surface elevation, imposing the palaeo-surface temperature over the last glacial cycle. As a present-day reference, we use the 1961-1990 standard climatology derived from simulations of the regional atmosphere model MAR with ERA reanalysis boundary conditions. For the palaeo-part of the spin-up, we add the temperature anomaly derived from the GRIP ice core to the years 1961-1990 average surface temperature field. For our projections, we apply surface temperature and surface mass balance anomalies derived from RCP 4.5 and RCP 8.5 scenarios created by MAR with boundary conditions from simulations with three CMIP5 models. The hybrid ice sheet model is fully coupled with the model of basal hydrology. With this model and the MAR scenarios, we perform simulations to estimate the contribution of the Greenland ice sheet to future sea level rise until the end of the 21st and 23rd centuries. Further on, the impact of elevation-surface mass balance feedback, introduced via the MAR data, on future sea level rise is inspected. In our projections, we found the Greenland ice sheet to contribute between 1.9 and 13.0 cm to global sea level rise until the year 2100 and between 3.5 and 76.4 cm until the year 2300, including our simulated additional sea level rise due to elevation-surface mass balance feedback. Translated into additional sea level rise, the strength of this feedback in the year 2100 varies from 0.4 to 1.7 cm, and in the year 2300 it ranges from 1.7 to 21.8 cm. Additionally, taking the Helheim and Store glaciers as examples, we investigate the role of ocean warming and surface runoff change for the melting of outlet glaciers. It shows that ocean temperature and subglacial discharge are about equally important for the melting of the examined outlet glaciers.
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    Chirped photonic crystal for spatially filtered optical feedback to a broad-area laser
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2018) Brée, Carsten; Gailevicius, Darius; Purlys, Vytautas; Werner, Guillermo Garre; Staliunas, Kestutis; Rathsfeld, Andreas; Schmidt, Gunther; Radziunas, Mindaugas
    We derive and analyze an efficient model for reinjection of spatially filtered optical feedback from an external resonator to a broad area, edge emitting semiconductor laser diode. Spatial filtering is achieved by a chirped photonic crystal, with variable periodicity along the optical axis and negligible resonant backscattering. The optimal chirp is obtained from a genetic algorithm, which yields solutions that are robust against perturbations. Extensive numerical simulations of the composite system with our optoelectronic solver indicate that spatially filtered reinjection enhances lower-order transversal optical modes in the laser diode and, consequently, improves the spatial beam quality.
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    Semantic modelling of video annotations – the TIB AV-Portal's metadata structure
    (Zenodo, 2018) Saurbier, Felix
    The TIB AV-Portal (https://av.tib.eu) is an online platform for sharing scientific videos operated by the German National Library of Science and Technology (TIB). Besides the allocation of Digital Object Identifiers (DOI) and Media Fragment Identifiers (MFID) for video citation, long-term preservation of all material and open licenses like Creative Commons, the core feature of the TIB AV-Portal are its various methods of automated metadata extraction to fundamentally improve search functionalities (e.g. fine-grained search and faceting). These comprise of an automated chaptering, extraction of superimposed text, speech to text recognition, and the detection of predefined visual concepts. In addition, extracted metadata are consequently mapped against authority files like the German “Gemeinsame Normdatei” and knowledge bases like DBpedia and Library of Congress Subject Headings via a process of automated named entity linking (NEL) to enable semantic and cross-lingual search. The results of this process are expressed as temporal and/or spatial video annotations, linking extracted metadata to certain key frames and video segments. In order to structure the data, express relations between single entities, and link to external information resources, several common vocabularies, ontologies and knowledge bases are being used. These include amongst others the Open Annotation Data Model, the NLP Interchange Format (NIF), BIBFRAME, the Friend of Friend Vocabulary (FOAF), and Schema.org. Furthermore, all data is stored adhering to the Resource Description Framework (RDF) data model and published as linked open data. This provides third parties with an interoperable and easy to reuse RDF graph representation of the AV-Portal’s metadata. On our poster we illustrate the general structure of the TIB AV-Portal’s comprehensive metadata both authoritative and extracted automatically. Here, the main focus is on the underlying video annotation graph model and on semantic interoperability and reusability of the data. In particular we visualize how the use of vocabularies, ontologies and knowledge bases allows for rich semantic descriptions of video materials as well as for easy metadata publication, interlinking, and opportunities of reuse by third parties (e.g. for information retrieval and enrichment). In doing so, we present the AV-Portal’s metadata structure as an illustrative example for the complexity of modelling temporal and spatial video metadata and as a set of best practices in the field of audio-visual resources.
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    Electrolytic Surface Treatment for Improved Adhesion between Carbon Fibre and Polycarbonate
    (Basel : MDPI, 2018) Kamps, Jan Henk; Henderson, Luke C.; Scheffler, Christina; Van der Heijden, Ruud; Simon, Frank; Bonizzi, Teena; Verghese, Nikhil
    To achieve good mechanical properties of carbon fibre-reinforced polycarbonate composites, the fibre-matrix adhesion must be dialled to an optimum level. The electrolytic surface treatment of carbon fibres during their production is one of the possible means of adapting the surface characteristics of the fibres. The production of a range of tailored fibres with varying surface treatments (adjusting the current, potential, and conductivity) was followed by contact angle, inverse gas chromatography and X-ray photoelectron spectroscopy measurements, which revealed a significant increase in polarity and hydroxyl, carboxyl, and nitrile groups on the fibre surface. Accordingly, an increase in the fibre-matrix interaction indicated by a higher interfacial shear strength was observed with the single fibre pull-out force-displacement curves. The statistical analysis identified the correlation between the process settings, fibre surface characteristics, and the performance of the fibres during single fibre pull-out testing.
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    Endurance of quantum coherence due to particle indistinguishability in noisy quantum networks
    (London : Nature Publ. Group, 2018) Perez-Leija, Armando; Guzmán-Silva, Diego; León-Montiel, Roberto de J.; Gräfe, Markus; Heinrich, Matthias; Moya-Cessa, Hector; Busch, Kurt; Szameit, Alexander
    Quantum coherence, the physical property underlying fundamental phenomena such as multi-particle interference and entanglement, has emerged as a valuable resource upon which modern technologies are founded. In general, the most prominent adversary of quantum coherence is noise arising from the interaction of the associated dynamical system with its environment. Under certain conditions, however, the existence of noise may drive quantum and classical systems to endure intriguing nontrivial effects. In this vein, here we demonstrate, both theoretically and experimentally, that when two indistinguishable non-interacting particles co-propagate through quantum networks affected by non-dissipative noise, the system always evolves into a steady state in which coherences accounting for particle indistinguishabilty perpetually prevail. Furthermore, we show that the same steady state with surviving quantum coherences is reached even when the initial state exhibits classical correlations.
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    Thinning Can Reduce Losses in Carbon Use Efficiency and Carbon Stocks in Managed Forests Under Warmer Climate
    (Fort Collins, Colo. : [Verlag nicht ermittelbar], 2018) Collalti, Alessio; Trotta, Carlo; Keenan, Trevor F.; Ibrom, Andreas; Bond‐Lamberty, Ben; Grote, Ruediger; Vicca, Sara; Reyer, Christopher P. O.; Migliavacca, Mirco; Veroustraete, Frank; Anav, Alessandro; Campioli, Matteo; Scoccimarro, Enrico; Šigut, Ladislav; Grieco, Elisa; Cescatti, Alessandro; Matteucci, Giorgio
    Forest carbon use efficiency (CUE, the ratio of net to gross primary productivity) represents the fraction of photosynthesis that is not used for plant respiration. Although important, it is often neglected in climate change impact analyses. Here we assess the potential impact of thinning on projected carbon cycle dynamics and implications for forest CUE and its components (i.e., gross and net primary productivity and plant respiration), as well as on forest biomass production. Using a detailed process-based forest ecosystem model forced by climate outputs of five Earth System Models under four representative climate scenarios, we investigate the sensitivity of the projected future changes in the autotrophic carbon budget of three representative European forests. We focus on changes in CUE and carbon stocks as a result of warming, rising atmospheric CO2 concentration, and forest thinning. Results show that autotrophic carbon sequestration decreases with forest development, and the decrease is faster with warming and in unthinned forests. This suggests that the combined impacts of climate change and changing CO2 concentrations lead the forests to grow faster, mature earlier, and also die younger. In addition, we show that under future climate conditions, forest thinning could mitigate the decrease in CUE, increase carbon allocation into more recalcitrant woody pools, and reduce physiological-climate-induced mortality risks. Altogether, our results show that thinning can improve the efficacy of forest-based mitigation strategies and should be carefully considered within a portfolio of mitigation options.
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    Fusion of MALDI Spectrometric Imaging and Raman Spectroscopic Data for the Analysis of Biological Samples
    (Lausanne : Frontiers Media, 2018) Ryabchykov, Oleg; Popp, Jürgen; Bocklitz, Thomas W.
    Despite of a large number of imaging techniques for the characterization of biological samples, no universal one has been reported yet. In this work, a data fusion approach was investigated for combining Raman spectroscopic data with matrix-assisted laser desorption/ionization (MALDI) mass spectrometric data. It betters the image analysis of biological samples because Raman and MALDI information can be complementary to each other. While MALDI spectrometry yields detailed information regarding the lipid content, Raman spectroscopy provides valuable information about the overall chemical composition of the sample. The combination of Raman spectroscopic and MALDI spectrometric imaging data helps distinguishing different regions within the sample with a higher precision than would be possible by using either technique. We demonstrate that a data weighting step within the data fusion is necessary to reveal additional spectral features. The selected weighting approach was evaluated by examining the proportions of variance within the data explained by the first principal components of a principal component analysis (PCA) and visualizing the PCA results for each data type and combined data. In summary, the presented data fusion approach provides a concrete guideline on how to combine Raman spectroscopic and MALDI spectrometric imaging data for biological analysis.
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    TiO2 as Photosensitizer and Photoinitiator for Synthesis of Photoactive TiO2-PEGDA Hydrogel Without Organic Photoinitiator
    (Lausanne : Frontiers Media, 2018-8-7) Glass, Sarah; Trinklein, Betsy; Abel, Bernd; Schulze, Agnes
    The replacement of potentially toxic photoinitiators is of increasing interest regarding the synthesis of biomaterials by photopolymerization. Therefore, we present a new method for the preparation of UV polymerized hydrogels with TiO2 as a photoinitiator. Titania is known to be an excellent photoactive compound which is non-toxic, inert, and cheap. The so-formed hydrogels possess excellent mechanical properties, a high swelling ratio, and high thermal stability. Furthermore, no TiO2 is released from the hydrogels. Thus, the material is highly suitable for medical applications. Additionally, the present TiO2 in the hydrogels remains photoactive as demonstrated by degradation of methylene blue. This enables the application of TiO2-hydrogels in photodynamic therapy.
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    Gradient and Generic systems in the space of fluxes, applied to reacting particle systems
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2018) Renger, D.R. Michiel
    In a previous work we devised a framework to derive generalised gradient systems for an evolution equation from the large deviations of an underlying microscopic system, in the spirit of the Onsager-Machlup relations. Of particular interest is the case where the microscopic system consists of random particles, and the macroscopic quantity is the empirical measure or concentration. In this work we take the particle flux as the macroscopic quantity, which is related to the concentration via a continuity equation. By a similar argument the large deviations can induce a generalised gradient or Generic system in the space of fluxes. In a general setting we study how flux gradient or generic systems are related to gradient systems of concentrations. The arguments are explained by the example of reacting particle systems, which is later expanded to include spatial diffusion as well.
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    When optimization for governing human-environment tipping elements is neither sustainable nor safe
    (London : Nature Publishing Group, 2018) Barfuss, W.; Donges, J.F.; Lade, S.J.; Kurths, J.
    Optimizing economic welfare in environmental governance has been criticized for delivering short-term gains at the expense of long-term environmental degradation. Different from economic optimization, the concepts of sustainability and the more recent safe operating space have been used to derive policies in environmental governance. However, a formal comparison between these three policy paradigms is still missing, leaving policy makers uncertain which paradigm to apply. Here, we develop a better understanding of their interrelationships, using a stylized model of human-environment tipping elements. We find that no paradigm guarantees fulfilling requirements imposed by another paradigm and derive simple heuristics for the conditions under which these trade-offs occur. We show that the absence of such a master paradigm is of special relevance for governing real-world tipping systems such as climate, fisheries, and farming, which may reside in a parameter regime where economic optimization is neither sustainable nor safe.