1,914 research outputs found

    Neue Spincrossover-Komplexe zur Photoschaltung des magnetischen Momentes im Festkörper, in Lösung und auf Oberflächen: Synthetische, sowie spektroskopische Untersuchungen

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    Das reversible Schalten des Magnetismus eines einzelnen Moleküls bei Raumtemperatur mittels elektromagnetischer Strahlung war das Ziel der vorliegenden Dissertation. Dazu wurden neue Eisen(II)-Spincrossover-Komplexe mit photoschaltbaren Phenylazo-Bipyridin-Liganden entworfen, synthetisiert und charakterisiert. Zunächst erfolgte die Untersuchung der photoinduzierten Isomerisierung der neuen bidentaten Liganden mithilfe der UV/Vis- und der 1H-NMR-Spektroskopie. Die synthetisierten Liganden wurden an ein Eisen(II)-Metallzentrum koordiniert, um Phenylazo-funktionalisierte Analoga zu bekannten Spincrossover-Komplexen zu erhalten. Dies diente dem Zweck, den Einfluss der Phenylazo-Einheit auf den Spinübergang und die kooperativen Wechselwirkungen im Festkörper zu analysieren. Der Spinzustandswechsel der neuen Verbindungen wurde durch magnetische Suszeptibilitätsmessungen, Mößbauer-, UV/Vis- und schwingungsspektroskopische Methoden untersucht. Des Weiteren wurden diese Komplexe in Lösung und in einer PMMA-Matrix mithilfe der UV/Vis-Spektroskopie und der NMR-Methode nach Evans auf die reversible photoinduzierte Änderung des magnetischen Momentes hin untersucht. Durch die Synthese von [Eisen(II)(L)]-low-spin-Komplexen gelang es, den Prozess der Photoisomerisierung der koordinierten Phenylazobipyridin-Liganden mithilfe der UV/Vis- und der 1H-NMR-Spektroskopie zu analysieren. Darüber hinaus konnte ein weiterer neuer photoschaltbarer Ligand auf Basis des 2,2’-Bipyridins synthetisiert werden, welcher durch die Photoisomerisierung zwischen einer (kappa)2- und einer (kappa)3-Koordination reversibel geschaltet werden sollte. Im abschließenden Teil der erzielten Ergebnisse wurden neue Eisen(II)- bzw. Eisen(III)-Komplexe für die mögliche Oberflächenfixierung von Spincrossover-Molekülen synthetisiert

    Evaluation of a real-time simulation environment for helicopter air-to-air refuelling investigations

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    The ability to perform air-to-air refuelling (AAR) can dramatically extend the utility of helicopters, through effectively providing unlimited range. For helicopters, AAR is typically performed utilising the probe-and-drogue aerial refuelling method. This is a complex manoeuver, where normally both the helicopter and tanker aircraft are operating at the limits of their flight envelopes. In addition, the wake flow from the tanker aircraft can cause a significant disturbance on the refuelling helicopter. This paper presents the initial evaluation of an AAR scenario constructed within DLR’s flight simulator, the Air Vehicle Simulator (AVES), based on current procedures and pilot interviews. A mission task was defined to assess the scenario in AVES and results are subsequently discussed. For pilots unfamiliar to formation flight or HAAR, the results show the difficulty of the flying task itself at the given cueing. Measures for improvement in future investigations are suggested

    Minimum Information About a Simulation Experiment (MIASE)

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    The original publication is available at www.ploscompbiol.orgReproducibility of experiments is a basic requirement for science. Minimum Information (MI) guidelines have proved a helpful means of enabling reuse of existing work in modern biology. The Minimum Information Required in the Annotation of Models (MIRIAM) guidelines promote the exchange and reuse of biochemical computational models. However, information about a model alone is not sufficient to enable its efficient reuse in a computational setting. Advanced numerical algorithms and complex modeling workflows used in modern computational biology make reproduction of simulations difficult. It is therefore essential to define the core information necessary to perform simulations of those models. The Minimum Information About a Simulation Experiment describes the minimal set of information that must be provided to make the description of a simulation experiment available to others. It includes the list of models to use and their modifications, all the simulation procedures to apply and in which order, the processing of the raw numerical results, and the description of the final output. MIASE allows for the reproduction of any simulation experiment. The provision of this information, along with a set of required models, guarantees that the simulation experiment represents the intention of the original authors. Following MIASE guidelines will thus improve the quality of scientific reporting, and will also allow collaborative, more distributed efforts in computational modeling and simulation of biological processes.The discussions that led to the definition of MIASE benefited from the support of a Japan Partnering Award by the UK Biotechnology and Biological Sciences Research Council. DW was supported by the Marie Curie program and by the German Research Association (DFG Research Training School ‘‘dIEM oSiRiS’’ 1387/1). This publication is based on work (EJC) supported in part by Award No KUK-C1-013-04, made by King Abdullah University of Science and Technology (KAUST). FTB acknowledges support by the NIH (grant 1R01GM081070- 01). JC is supported by the European Commission, DG Information Society, through the Seventh Framework Programme of Information and Communication Technologies, under the VPH NoE project (grant number 223920). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Publishers versio

    Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

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    A measurement of the cosmic-ray spectrum for energies exceeding 4×10184{\times}10^{18} eV is presented, which is based on the analysis of showers with zenith angles greater than 6060^{\circ} detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above 5.3×10185.3{\times}10^{18} eV, the "ankle", the flux can be described by a power law EγE^{-\gamma} with index γ=2.70±0.02(stat)±0.1(sys)\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)} followed by a smooth suppression region. For the energy (EsE_\text{s}) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find Es=(5.12±0.25(stat)1.2+1.0(sys))×1019E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19} eV.Comment: Replaced with published version. Added journal reference and DO

    Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

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    The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO

    Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

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    We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principle calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI. Supplemental material in the ancillary file

    First results from the AugerPrime Radio Detector

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