TY - JOUR A1 - Kosmala, Aleksander A1 - Gruschwitz, Philipp A1 - Veldhoen, Simon A1 - Weng, Andreas Max A1 - Krauss, Bernhard A1 - Bley, Thorsten Alexander A1 - Petritsch, Bernhard T1 - Dual-energy CT angiography in suspected pulmonary embolism: influence of injection protocols on image quality and perfused blood volume JF - The International Journal of Cardiovascular Imaging N2 - Abstract To compare intravenous contrast material (CM) injection protocols for dual-energy CT pulmonary angiography (CTPA) in patients with suspected acute pulmonary embolism with regard to image quality and pulmonary perfused blood volume (PBV) values. A total of 198 studies performed with four CM injection protocols varying in CM volume and iodine delivery rates (IDR) were retrospectively included: (A) 60 ml at 5 ml/s (IDR = 1.75gI/s), (B) 50 ml at 5 ml/s (IDR = 1.75gI/s), (C) 50 ml at 4 ml/s (IDR = 1.40gI/s), (D) 40 ml at 3 ml/s (IDR = 1.05gI/s). Image quality and PBV values at different resolution settings were compared. Pulmonary arterial tract attenuation was highest for protocol A (397 ± 110 HU; p vs. B = 0.13; vs. C = 0.02; vs. D < 0.001). CTPA image quality of protocol A was rated superior compared to protocols B and D by reader 1 (p = 0.01; < 0.001), and superior to protocols B, C and D by reader 2 (p < 0.001; 0.02; < 0.001). Otherwise, there were no significant differences in CTPA quality ratings. Subjective iodine map ratings did not vary significantly between protocols A, B, and C. Both readers rated protocol D inferior to all other protocols (p < 0.05). PBV values did not vary significantly between protocols A and B at resolution settings of 1, 4 and 10 (p = 0.10; 0.10; 0.09), while otherwise PBV values displayed a decreasing trend from protocol A to D (p < 0.05). Higher CM volume and IDR are associated with superior CTPA and iodine map quality and higher absolute PBV values. KW - CT KW - dual-energy CT KW - pulmonary embolism KW - contrast media Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-314739 SN - 1569-5794 SN - 1573-0743 VL - 36 IS - 10 ER - TY - GEN A1 - Kosmala, Aleksander A1 - Gruschwitz, Philipp A1 - Veldhoen, Simon A1 - Weng, Andreas Max A1 - Krauss, Bernhard A1 - Bley, Thorsten Alexander A1 - Petritsch, Bernhard T1 - Correction to: Dual-energy CT angiography in suspected pulmonary embolism: infuence of injection protocols on image quality and perfused blood volume T2 - The International Journal of Cardiovascular Imaging N2 - No abstract available. KW - correction Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-350830 VL - 38 IS - 3 SP - 707 ER - TY - INPR A1 - Huber, Bernhard A1 - Pres, Sebastian A1 - Wittmann, Emanuel A1 - Dietrich, Lysanne A1 - Lüttig, Julian A1 - Fersch, Daniel A1 - Krauss, Enno A1 - Friedrich, Daniel A1 - Kern, Johannes A1 - Lisinetskii, Victor A1 - Hensen, Matthias A1 - Hecht, Bert A1 - Bratschitsch, Rudolf A1 - Riedle, Eberhard A1 - Brixner, Tobias T1 - Space- and time-resolved UV-to-NIR surface spectroscopy and 2D nanoscopy at 1 MHz repetition rate N2 - We describe a setup for time-resolved photoemission electron microscopy (TRPEEM) with aberration correction enabling 3 nm spatial resolution and sub-20 fs temporal resolution. The latter is realized by our development of a widely tunable (215–970 nm) noncollinear optical parametric amplifier (NOPA) at 1 MHz repetition rate. We discuss several exemplary applications. Efficient photoemission from plasmonic Au nanoresonators is investigated with phase-coherent pulse pairs from an actively stabilized interferometer. More complex excitation fields are created with a liquid-crystal-based pulse shaper enabling amplitude and phase shaping of NOPA pulses with spectral components from 600 to 800 nm. With this system we demonstrate spectroscopy within a single plasmonic nanoslit resonator by spectral amplitude shaping and investigate the local field dynamics with coherent two-dimensional (2D) spectroscopy at the nanometer length scale (“2D nanoscopy”). We show that the local response varies across a distance as small as 33 nm in our sample. Further, we report two-color pump–probe experiments using two independent NOPA beamlines. We extract local variations of the excited-state dynamics of a monolayered 2D material (WSe2) that we correlate with low-energy electron microscopy (LEEM) and reflectivity (LEER) measurements. Finally, we demonstrate the in-situ sample preparation capabilities for organic thin films and their characterization via spatially resolved electron diffraction and dark-field LEEM. KW - Photoemission electron microscopy PEEM KW - Low energy electron microscopy LEEM KW - Spatially resolved 2D spectroscopy KW - Two-color pump-probe spectroscopy KW - Time-resolved photoemission electron microscopy Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-191906 SN - 0034-6748 N1 - This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Review of Scientific Instruments 90, 113103 (2019); https://doi.org/10.1063/1.5115322 and may be found at https://doi.org/10.1063/1.5115322. ER - TY - JOUR A1 - Cornelius, Christine A1 - Leingärtner, Annette A1 - Hoiss, Bernhard A1 - Krauss, Jochen A1 - Steffan-Dewenter, Ingolf A1 - Menzel, Annette T1 - Phenological response of grassland species to manipulative snowmelt and drought along an altitudinal gradient JF - Journal of Experimental Botany N2 - Plant communities in the European Alps are assumed to be highly affected by climate change, as the temperature rise in this region is above the global average. It is predicted that higher temperatures will lead to advanced snowmelt dates and that the number of extreme weather events will increase. The aims of this study were to determine the impacts of extreme climatic events on flower phenology and to assess whether those impacts differed between lower and higher altitudes. In 2010, an experiment simulating advanced and delayed snowmelt as well as a drought event was conducted along an altitudinal transect approximately every 250 m (600–2000 m above sea level) in the Berchtesgaden National Park, Germany. The study showed that flower phenology was strongly affected by altitude; however, there were few effects of the manipulative treatments on flowering. The effects of advanced snowmelt were significantly greater at higher than at lower sites, but no significant difference was found between both altitudinal bands for the other treatments. The response of flower phenology to temperature declined through the season and the length of flowering duration was not significantly influenced by treatments. The stronger effect of advanced snowmelt at higher altitudes may be a response to differences in treatment intensity across the gradient. Consequently, shifts in the date of snowmelt due to global warming may affect species more at higher than at lower altitudes, as changes may be more pronounced at higher altitudes. These data indicate a rather low risk of drought events on flowering phenology in the Bavarian Alps. KW - flowering KW - advanced KW - snowmelt KW - Alps KW - BBCH KW - climate change KW - delayed snowmelt Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-126888 VL - 64 IS - 1 ER - TY - JOUR A1 - Leingärtner, Annette A1 - Hoiss, Bernhard A1 - Krauss, Jochen A1 - Steffan-Dewenter, Ingolf T1 - Combined Effects of Extreme Climatic Events and Elevation on Nutritional Quality and Herbivory of Alpine Plants N2 - Climatic extreme events can cause the shift or disruption of plant-insect interactions due to altered plant quality, e.g. leaf carbon to nitrogen ratios, and phenology. However, the response of plant-herbivore interactions to extreme events and climatic gradients has been rarely studied, although climatic extremes will increase in frequency and intensity in the future and insect herbivores represent a highly diverse and functionally important group. We set up a replicated climate change experiment along elevational gradients in the German Alps to study the responses of three plant guilds and their herbivory by insects to extreme events (extreme drought, advanced and delayed snowmelt) versus control plots under different climatic conditions on 15 grassland sites. Our results indicate that elevational shifts in CN (carbon to nitrogen) ratios and herbivory depend on plant guild and season. CN ratios increased with altitude for grasses, but decreased for legumes and other forbs. In contrast to our hypotheses, extreme climatic events did not significantly affect CN ratios and herbivory. Thus, our study indicates that nutritional quality of plants and antagonistic interactions with insect herbivores are robust against seasonal climatic extremes. Across the three functional plant guilds, herbivory increased with nitrogen concentrations. Further, increased CN ratios indicate a reduction in nutritional plant quality with advancing season. Although our results revealed no direct effects of extreme climatic events, the opposing responses of plant guilds along elevation imply that competitive interactions within plant communities might change under future climates, with unknown consequences for plant-herbivore interactions and plant community composition. KW - Plant-herbivore interactions KW - Herbivory KW - Leaves KW - Grasses KW - Legumes KW - Insects KW - Drought KW - Climate Change Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-112812 ER - TY - THES A1 - Krauß, Martin Bernhard T1 - Testing Models with Higher Dimensional Effective Interactions at the LHC and Dark Matter Experiments T1 - Tests von Modellen mit höherdimensionalen effektiven Operatoren am LHC und Experimenten zur Suche dunkler Materie N2 - Dark matter and non-zero neutrino masses are possible hints for new physics beyond the Standard Model of particle physics. Such potential consequences of new physics can be described by effective field theories in a model independent way. It is possible that the dominant contribution to low-energy effects of new physics is generated by operators of dimension d>5, e.g., due to an additional symmetry. Since these are more suppressed than the usually discussed lower dimensional operators, they can lead to extremly weak interactions even if new physics appears at comparatively low scales. Thus neutrino mass models can be connected to TeV scale physics, for instance. The possible existence of TeV scale particles is interesting, since they can be potentially observed at collider experiments, such as the Large Hadron Collider. Hence, we first recapitulate the generation of neutrino masses by higher dimensional effective operators in a supersymmetric framework. In addition, we discuss processes that can be used to test these models at the Large Hadron Collider. The introduction of new particles can affect the running of gauge couplings. Hence, we study the compatibilty of these models with Grand Unified Theories. The required extension of these models can imply the existence of new heavy quarks, which requires the consideration of cosmological constraints. Finally, higher dimensional effective operators can not only generate small neutrino masses. They also can be used to discuss the interactions relevant for dark matter detection experiments. Thus we apply the methods established for the study of neutrino mass models to the systematic discussion of higher dimensional effective operators generating dark matter interactions. N2 - Dunkle Materie und nichtverschwindende Neutrinomassen sind nur zwei Hinweise auf das mögliche Vorhandensein neuer Physik jenseits des Standardmodells der Teilchenphysik. Solche möglichen Konsequenzen neuer Physik können modellunabhängig mit effektiven Feldtheorien beschrieben werden. Beispielsweise aufgrund zusätzlicher Symmetrien ist es möglich, dass Operatoren mit Dimension $d>5$ den dominanten Beitrag zu den Effekten neuer Physik bei niedrigen Energieskalen liefern. Da diese stärker unterdrückt sind als die gewöhnlicherweise betrachteten Operatoren niedrigerer Dimension, können sie zu äußerst schwachen Wechselwirkungen führen, selbst wenn neue Physik bereits bei vergleichsweise niedrigen Energien auftritt. Dies ermöglicht unter anderem neue Teilchen mit Massen im Bereich der TeV-Skala mit der Erzeugung der sehr geringen Neutrinomassen in Verbindung zu bringen. Solche Teilchen sind besonders interessant, da sie an Beschleunigerexperimenten wie dem Large Hadron Collider untersucht werden können. Deswegen wird in dieser Arbeit zunächst die Erzeugung von Neutrinomassen durch höherdimensionale effektive Operatoren in supersymmetrischen Modellen rekapituliert. Darüber hinaus sollen mögliche Prozesse zum Nachweis dieser Modelle am Large Hadron Collider anhand eines Beispiels diskutiert werden. Da das Einführen neuer Teilchen das Laufen der Kopplungskonstanten beeinflussen kann, wird ferner betrachtet, inwiefern solche Szenarien vereinbar mit großen vereinheitlichten Theorien (Grand Unified Theories) sind. Die entsprechende Erweiterung dieser Modelle kann beispielsweise das Auftreten neuer schwerer Quarks zur Folge haben, die auf ihre Vereinbarkeit mit kosmologischen Beobachtungen untersucht werden. Höherdimensionale Operatoren können jedoch nicht nur sehr kleine Neutrinomassen erzeugen, sondern auch für Experimente zum Nachweis dunkler Materie relevant sein. Daher sollen die zuvor angewandten Methoden zur systematischen Diskussion effektiver Operatoren, die Wechselwirkungen dunkler Materie beschreiben, verwendet werden. KW - Neutrino KW - Supersymmetrie KW - Dunkle Materie KW - Effektive Theorie KW - Theoretische Teilchenphysik KW - Theoretical High Energy Physics KW - Neutrino Physics KW - Neutrinophysik KW - Supersymmetry KW - Supersymmetrie KW - Dark Matter KW - Dunkle Materie KW - Effective Field Theory KW - Effektive Feldtheorien KW - Elementarteilchenphysik Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-94519 ER - TY - JOUR A1 - Aeschlimann, Martin A1 - Brixner, Tobias A1 - Cinchetti, Mirko A1 - Frisch, Benjamin A1 - Hecht, Bert A1 - Hensen, Matthias A1 - Huber, Bernhard A1 - Kramer, Christian A1 - Krauss, Enno A1 - Loeber, Thomas H. A1 - Pfeiffer, Walter A1 - Piecuch, Martin A1 - Thielen, Philip T1 - Cavity-assisted ultrafast long-range periodic energy transfer between plasmonic nanoantennas JF - Light: Science & Applications N2 - Radiationless energy transfer is at the core of diverse phenomena, such as light harvesting in photosynthesis\(^1\), energy-transfer-based microspectroscopies\(^2\), nanoscale quantum entanglement\(^3\) and photonic-mode hybridization\(^4\). Typically, the transfer is efficient only for separations that are much shorter than the diffraction limit. This hampers its application in optical communication and quantum information processing, which require spatially selective addressing. Here, we demonstrate highly efficient radiationless coherent energy transfer over a distance of twice the excitation wavelength by combining localized and delocalized\(^5\) plasmonic modes. Analogous to the Tavis-Cummings model, two whispering-gallery-mode antennas\(^6\) placed in the foci of an elliptical plasmonic cavity\(^7\) fabricated from single-crystal gold plates act as a pair of oscillators coupled to a common cavity mode. Time-resolved two-photon photoemission electron microscopy (TR 2P-PEEM) reveals an ultrafast long-range periodic energy transfer in accordance with the simulations. Our observations open perspectives for the optimization and tailoring of mesoscopic energy transfer and long-range quantum emitter coupling. KW - chemistry KW - nanocavities KW - nanophotonics and plasmonics KW - photonic devices Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173265 VL - 6 ER -