TY - JOUR A1 - Brinkmann, Kai Oliver A1 - Becker, Tim A1 - Zimmermann, Florian A1 - Kreusel, Cedric A1 - Gahlmann, Tobias A1 - Theisen, Manuel A1 - Haeger, Tobias A1 - Olthof, Selina A1 - Tückmantel, Christian A1 - Günster, M. A1 - Maschwitz, Timo A1 - Göbelsmann, Fabian A1 - Koch, Christine A1 - Hertel, Dirk A1 - Caprioglio, Pietro A1 - Peña-Camargo, Francisco A1 - Perdigón-Toro, Lorena A1 - Al-Ashouri, Amran A1 - Merten, Lena A1 - Hinderhofer, Alexander A1 - Gomell, Leonie A1 - Zhang, Siyuan A1 - Schreiber, Frank A1 - Albrecht, Steve A1 - Meerholz, Klaus A1 - Neher, Dieter A1 - Stolterfoht, Martin A1 - Riedl, Thomas T1 - Perovskite-organic tandem solar cells with indium oxide interconnect JF - Nature N2 - Multijunction solar cells can overcome the fundamental efficiency limits of single-junction devices. The bandgap tunability of metal halide perovskite solar cells renders them attractive for multijunction architectures(1). Combinations with silicon and copper indium gallium selenide (CIGS), as well as all-perovskite tandem cells, have been reported(2-5). Meanwhile, narrow-gap non-fullerene acceptors have unlocked skyrocketing efficiencies for organic solar cells(6,7). Organic and perovskite semiconductors are an attractive combination, sharing similar processing technologies. Currently, perovskite-organic tandems show subpar efficiencies and are limited by the low open-circuit voltage (V-oc) of wide-gap perovskite cells(8) and losses introduced by the interconnect between the subcells(9,10). Here we demonstrate perovskite-organic tandem cells with an efficiency of 24.0 per cent (certified 23.1 per cent) and a high V-oc of 2.15 volts. Optimized charge extraction layers afford perovskite subcells with an outstanding combination of high V-oc and fill factor. The organic subcells provide a high external quantum efficiency in the near-infrared and, in contrast to paradigmatic concerns about limited photostability of non-fullerene cells(11), show an outstanding operational stability if excitons are predominantly generated on the non-fullerene acceptor, which is the case in our tandems. The subcells are connected by an ultrathin (approximately 1.5 nanometres) metal-like indium oxide layer with unprecedented low optical/electrical losses. This work sets a milestone for perovskite-organic tandems, which outperform the best p-i-n perovskite single junctions(12) and are on a par with perovskite-CIGS and all-perovskite multijunctions(13). Y1 - 2022 U6 - https://doi.org/10.1038/s41586-022-04455-0 SN - 0028-0836 SN - 1476-4687 VL - 604 IS - 7905 SP - 280 EP - 286 PB - Nature Research CY - Berlin ER - TY - JOUR A1 - Bulla, Mattia A1 - Coughlin, Michael W. A1 - Dhawan, Suhail A1 - Dietrich, Tim T1 - Multi-messenger constraints on the Hubble constant through combination of gravitational waves, gamma-ray bursts and kilonovae from neutron star mergers JF - Universe : open access journal N2 - The simultaneous detection of gravitational waves and light from the binary neutron star merger GW170817 led to independent measurements of distance and redshift, providing a direct estimate of the Hubble constant H-0 that does not rely on a cosmic distance ladder, nor assumes a specific cosmological model. By using gravitational waves as "standard sirens", this approach holds promise to arbitrate the existing tension between the H-0 value inferred from the cosmic microwave background and those obtained from local measurements. However, the known degeneracy in the gravitational-wave analysis between distance and inclination of the source led to a H-0 value from GW170817 that was not precise enough to resolve the existing tension. In this review, we summarize recent works exploiting the viewing-angle dependence of the electromagnetic signal, namely the associated short gamma-ray burst and kilonova, to constrain the system inclination and improve on H-0. We outline the key ingredients of the different methods, summarize the results obtained in the aftermath of GW170817 and discuss the possible systematics introduced by each of these methods. KW - gravitational waves KW - stars: neutron KW - stars: binaries KW - cosmology: cosmological parameters KW - cosmology: distance scale KW - cosmology: cosmic background radiation Y1 - 2022 U6 - https://doi.org/10.3390/universe8050289 SN - 2218-1997 VL - 8 IS - 5 PB - MDPI CY - Basel ER - TY - THES A1 - Büchner, Robby T1 - Understanding local electronic structure variations in bio-inspired aromatic molecules T1 - Erkenntnisse über lokale Variationen der elektronischen Struktur in biologisch inspirierten aromatischen Molekülen N2 - In this thesis, the dependencies of charge localization and itinerance in two classes of aromatic molecules are accessed: pyridones and porphyrins. The focus lies on the effects of isomerism, complexation, solvation, and optical excitation, which are concomitant with different crucial biological applications of specific members of these groups of compounds. Several porphyrins play key roles in the metabolism of plants and animals. The nucleobases, which store the genetic information in the DNA and RNA are pyridone derivatives. Additionally, a number of vitamins are based on these two groups of substances. This thesis aims to answer the question of how the electronic structure of these classes of molecules is modified, enabling the versatile natural functionality. The resulting insights into the effect of constitutional and external factors are expected to facilitate the design of new processes for medicine, light-harvesting, catalysis, and environmental remediation. The common denominator of pyridones and porphyrins is their aromatic character. As aromaticity was an early-on topic in chemical physics, the overview of relevant theoretical models in this work also mirrors the development of this scientific field in the 20th century. The spectroscopic investigation of these compounds has long been centered on their global, optical transition between frontier orbitals. The utilization and advancement of X-ray spectroscopic methods characterizing the local electronic structure of molecular samples form the core of this thesis. The element selectivity of the near-edge X-ray absorption fine structure (NEXAFS) is employed to probe the unoccupied density of states at the nitrogen site, which is key for the chemical reactivity of pyridones and porphyrins. The results contribute to the growing database of NEXAFS features and their interpretation, e.g., by advancing the debate on the porphyrin N K-edge through systematic experimental and theoretical arguments. Further, a state-of-the-art laser pump – NEXAFS probe scheme is used to characterize the relaxation pathway of a photoexcited porphyrin on the atomic level. Resonant inelastic X-ray scattering (RIXS) provides complementary results by accessing the highest occupied valence levels including symmetry information. It is shown that RIXS is an effective experimental tool to gain detailed information on charge densities of individual species in tautomeric mixtures. Additionally, the hRIXS and METRIXS high-resolution RIXS spectrometers, which have been in part commissioned in the course of this thesis, will gain access to the ultra-fast and thermal chemistry of pyridones, porphyrins, and many other compounds. With respect to both classes of bio-inspired aromatic molecules, this thesis establishes that even though pyridones and porphyrins differ largely by their optical absorption bands and hydrogen bonding abilities, they all share a global stabilization of local constitutional changes and relevant external perturbation. It is because of this wide-ranging response that pyridones and porphyrins can be applied in a manifold of biological and technical processes. N2 - In dieser Arbeit werden die Abhängigkeiten von Ladungslokalisierung und -wanderung in zwei Klassen von aromatischen Molekülen untersucht: Pyridone und Porphyrine. Der Schwerpunkt liegt auf den Auswirkungen von Isomerie, Komplexierung, Lösung (in Wasser) und optischer Anregung, die mit verschiedenen entscheidenden biologischen Anwendungen spezifischer Mitglieder dieser Gruppen von Verbindungen einhergehen. Mehrere Porphyrine spielen eine Schlüsselrolle im Stoffwechsel von Pflanzen und Tieren. Die Nukleobasen, die die genetische Information in der DNA und RNA speichern, sind Pyridonderivate. Auch mehrere Vitamine basieren auf diesen beiden Stoffgruppen. Ziel dieser Arbeit ist es, die Frage zu beantworten, wie die elektronische Struktur dieser Molekülklassen modifiziert wird, sodass die vielfältigen Funktionen in der Natur ermöglicht werden. Die sich daraus ergebenden Erkenntnisse über die Wirkung konstitutioneller und externer Einflussfaktoren ermöglichen die Entwicklung neuer Verfahren in der Medizin, Katalyse, Solar- und Umwelttechnik. Die Gemeinsamkeit von Pyridonen und Porphyrinen ist ihr aromatischer Charakter. Da Aromatizität von Beginn der chemischen Physik an thematisiert wurde, spiegelt der Überblick relevanter theoretischer Modelle in dieser Arbeit auch die Entwicklung dieses Wissenschaftsgebiets im 20. Jahrhundert wieder. Die spektroskopische Untersuchung dieser Verbindungen konzentrierte sich lange Zeit auf die globalen, optischen Übergänge zwischen den Grenzorbitalen. Die Anwendung und Weiterentwicklung röntgenspektroskopischer Methoden zur Charakterisierung der lokalen elektronischen Struktur von molekularen Proben bilden den Kern dieser Arbeit. Die Elementselektivität der Röntgen-Nahkanten-Absorptions-Spektroskopie (NEXAFS) wird genutzt, um die unbesetzte Zustandsdichte an den Stickstoffatomen zu untersuchen, welche für die chemische Reaktivität von Pyridonen und Porphyrinen verantwortlich sind. Die Ergebnisse tragen zum wachsenden Bestand von NEXAFS-Spektren und ihrer Interpretation bei, z.B. indem sie die Debatte über die N K-Kante von Porphyrinen durch systematische experimentelle und theoretische Argumente voranbringen. Zudem wird ein modernes Laser-Pump – NEXAFS-Probe System verwendet, um den Relaxationsprozess eines photoangeregten Porphyrins auf atomarer Ebene zu charakterisieren. Die resonante inelastische Röntgenstreuung (RIXS) liefert komplementäre Ergebnisse, indem sie die höchsten besetzten Valenzniveaus einschließlich Symmetrieinformationen zugänglich macht. Es wird gezeigt, dass RIXS eine effektive experimentelle Methode ist, um detaillierte Informationen über die Ladungsdichten einzelner Tautomere in einem Gemisch zu erhalten. Zudem werden es die hochauflösenden RIXS-Spektrometer hRIXS und METRIXS, die im Rahmen dieser Arbeit mit in Betrieb genommen wurden, erlauben, Informationen zur ultraschnellen und thermischen Chemie von Pyridonen, Porphyrinen und vielen anderen Verbindungen zu gewinnen. Im Hinblick auf beide Klassen biologisch inspirierter, aromatischer Moleküle wird in dieser Arbeit gezeigt, dass sich Pyridone und Porphyrine zwar durch ihre optischen Absorptionsbanden und ihre Fähigkeit zu Wasserstoffbrückenbindungen unterscheiden, aber alle Verbindungen eine globale Stabilisierung lokaler Konstitutionsänderungen und relevanter äußerer Einflüsse aufweisen. Aufgrund dieser weitreichenden Anpassung können Pyridone und Porphyrine in einer Vielzahl von biologischen und technischen Prozessen eingesetzt werden. KW - NEXAFS KW - RIXS KW - X-ray spectroscopy KW - Aromaticity KW - Porphyrins KW - Pyridones KW - Röntgenspektroskopie KW - Aromatizität KW - Porphyrine KW - Pyridone KW - NEXAFS KW - RIXS Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-553192 ER - TY - JOUR A1 - Büchner, Robby A1 - da Cruz, Vinicius Vaz A1 - Grover, Nitika A1 - Charisiadis, Asterios A1 - Fondell, Mattis A1 - Haverkamp, Robert A1 - Senge, Mathias O. A1 - Föhlisch, Alexander T1 - Fundamental electronic changes upon intersystem crossing in large aromatic photosensitizers: free base 5,10,15,20-tetrakis(4-carboxylatophenyl)porphyrin JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - Free base 5,10,15,20-tetrakis(4-carboxylatophenyl)porphyrin stands for the class of powerful porphyrin photosensitizers for singlet oxygen generation and light-harvesting. The atomic level selectivity of dynamic UV pump - N K-edge probe X-ray absorption spectroscopy in combination with time-dependent density functional theory (TD-DFT) gives direct access to the crucial excited molecular states within the unusual relaxation pathway. The efficient intersystem crossing, that is El-Sayed forbidden and not facilitated by a heavy atom is confirmed to be the result of the long singlet excited state lifetime (Q(x) 4.9 ns) and thermal effects. Overall, the interplay of stabilization by conservation of angular momenta and vibronic relaxation drive the de-excitation in these chromophores. Y1 - 2022 U6 - https://doi.org/10.1039/d1cp05420a SN - 1463-9076 SN - 1463-9084 VL - 24 IS - 12 SP - 7505 EP - 7511 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Caesar, Levke A1 - McCarthy, Gerard D. A1 - Thornalley, David J. R. A1 - Cahill, Niamh A1 - Rahmstorf, Stefan T1 - Reply to: Atlantic circulation change still uncertain T2 - Nature geoscience Y1 - 2022 U6 - https://doi.org/10.1038/s41561-022-00897-3 SN - 1752-0894 SN - 1752-0908 VL - 15 IS - 3 SP - 168 EP - 170 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Cestnik, Rok A1 - Pikovskij, Arkadij T1 - Exact finite-dimensional reduction for a population of noisy oscillators and its link to Ott-Antonsen and Watanabe-Strogatz theories JF - Chaos : an interdisciplinary journal of nonlinear science N2 - Populations of globally coupled phase oscillators are described in the thermodynamic limit by kinetic equations for the distribution densities or, equivalently, by infinite hierarchies of equations for the order parameters. Ott and Antonsen [Chaos 18, 037113 (2008)] have found an invariant finite-dimensional subspace on which the dynamics is described by one complex variable per population. For oscillators with Cauchy distributed frequencies or for those driven by Cauchy white noise, this subspace is weakly stable and, thus, describes the asymptotic dynamics. Here, we report on an exact finite-dimensional reduction of the dynamics outside of the Ott-Antonsen subspace. We show that the evolution from generic initial states can be reduced to that of three complex variables, plus a constant function. For identical noise-free oscillators, this reduction corresponds to the Watanabe-Strogatz system of equations [Watanabe and Strogatz, Phys. Rev. Lett. 70, 2391 (1993)]. We discuss how the reduced system can be used to explore the transient dynamics of perturbed ensembles. Published under an exclusive license by AIP Publishing. Y1 - 2022 U6 - https://doi.org/10.1063/5.0106171 SN - 1054-1500 SN - 1089-7682 VL - 32 IS - 11 PB - AIP CY - Melville ER - TY - JOUR A1 - Cestnik, Rok A1 - Pikovsky, Arkady T1 - Hierarchy of exact low-dimensional reductions for populations of coupled oscillators JF - Physical review letters N2 - We consider an ensemble of phase oscillators in the thermodynamic limit, where it is described by a kinetic equation for the phase distribution density. We propose an Ansatz for the circular moments of the distribution (Kuramoto-Daido order parameters) that allows for an exact truncation at an arbitrary number of modes. In the simplest case of one mode, the Ansatz coincides with that of Ott and Antonsen [Chaos 18, 037113 (2008)]. Dynamics on the extended manifolds facilitate higher-dimensional behavior such as chaos, which we demonstrate with a simulation of a Josephson junction array. The findings are generalized for oscillators with a Cauchy-Lorentzian distribution of natural frequencies. Y1 - 2022 U6 - https://doi.org/10.1103/PhysRevLett.128.054101 SN - 0031-9007 SN - 1079-7114 VL - 128 IS - 5 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Ciarniello, Mauro A1 - Fulle, Marco A1 - Raponi, Andrea A1 - Filacchione, Gianrico A1 - Capaccioni, Fabrizio A1 - Rotundi, Alessandra A1 - Rinaldi, Giovanna A1 - Formisano, Michelangelo A1 - Magni, Gianfranco A1 - Tosi, Federico A1 - De Sanctis, Maria Cristina A1 - Capria, Maria Teresa A1 - Longobardo, Andrea A1 - Beck, Pierre A1 - Fornasier, Sonia A1 - Kappel, David A1 - Mennella, Vito A1 - Mottola, Stefano A1 - Rousseau, Batiste A1 - Arnold, Gabriele T1 - Macro and micro structures of pebble-made cometary nuclei reconciled by seasonal evolution JF - Nature astronomy N2 - Comets evolve due to sublimation of ices embedded inside porous dust, triggering dust emission (that is, erosion) followed by mass loss, mass redistribution and surface modifications. Surface changes were revealed by the Deep Impact and Stardust NExT missions for comet 9P/Tempel 1 (ref.(1)), and a full inventory of the processes modifying cometary nuclei was provided by Rosetta while it escorted comet 67P/Churyumov-Gerasimenko for approximately two years(2-4). Such observations also showed puzzling water-ice-rich spots that stood out as patches optically brighter and spectrally bluer than the average cometary surfaces(5-9). These are up to tens of metres large and indicate macroscopic compositional dishomogeneities apparently in contrast with the structural homogeneity above centimetre scales of pebble-made nuclei(10). Here we show that the occurrence of blue patches determines the seasonal variability of the nucleus colour(4,11,12) and gives insight into the internal structure of comets. We define a new model that links the centimetre-sized pebbles composing the nucleus(10) and driving cometary activity(13,14) to metre-sized water-ice-enriched blocks embedded in a drier matrix. The emergence of blue patches is due to the matrix erosion driven by CO2-ice sublimation that exposes the water-ice-enriched blocks, which in turn are eroded by water-ice sublimation when exposed to sunlight. Our model explains the observed seasonal evolution of the nucleus and reconciles the available data at micro (sub-centimetre) and macro (metre) scales. KW - Asteroids, comets and Kuiper belt KW - Planetary science Y1 - 2022 U6 - https://doi.org/10.1038/s41550-022-01625-y SN - 2397-3366 VL - 6 IS - 5 SP - 546 EP - 553 PB - Nature Research CY - Berlin ER - TY - JOUR A1 - Clark, Oliver J. A1 - Freyse, Friedrich A1 - Yashina, L. V. A1 - Rader, Oliver A1 - Sanchez-Barriga, Jaime T1 - Robust behavior and spin-texture stability of the topological surface state in Bi2Se3 upon deposition of gold JF - npj quantum materials N2 - The Dirac point of a topological surface state (TSS) is protected against gapping by time-reversal symmetry. Conventional wisdom stipulates, therefore, that only through magnetisation may a TSS become gapped. However, non-magnetic gaps have now been demonstrated in Bi2Se3 systems doped with Mn or In, explained by hybridisation of the Dirac cone with induced impurity resonances. Recent photoemission experiments suggest that an analogous mechanism applies even when Bi2Se3 is surface dosed with Au. Here, we perform a systematic spin- and angle-resolved photoemission study of Au-dosed Bi2Se3. Although there are experimental conditions wherein the TSS appears gapped due to unfavourable photoemission matrix elements, our photon-energy-dependent spectra unambiguously demonstrate the robustness of the Dirac cone against high Au coverage. We further show how the spin textures of the TSS and its accompanying surface resonances remain qualitatively unchanged following Au deposition, and discuss the mechanism underlying the suppression of the spectral weight. KW - Electronic properties and materials KW - Topological matter Y1 - 2022 U6 - https://doi.org/10.1038/s41535-022-00443-9 SN - 2397-4648 VL - 7 IS - 1 PB - Nature Publishing Group CY - London ER - TY - JOUR A1 - Clark, Oliver J. A1 - Wadgaonkar, Indrajit A1 - Freyse, Friedrich A1 - Springholz, Gunther A1 - Battiato, Marco A1 - Sanchez-Barriga, Jaime T1 - Ultrafast thermalization pathways of excited bulk and surface states in the ferroelectric rashba semiconductor GeTe JF - Advanced materials N2 - A large Rashba effect is essential for future applications in spintronics. Particularly attractive is understanding and controlling nonequilibrium properties of ferroelectric Rashba semiconductors. Here, time- and angle-resolved photoemission is utilized to access the ultrafast dynamics of bulk and surface transient Rashba states after femtosecond optical excitation of GeTe. A complex thermalization pathway is observed, wherein three different timescales can be clearly distinguished: intraband thermalization, interband equilibration, and electronic cooling. These dynamics exhibit an unconventional temperature dependence: while the cooling phase speeds up with increasing sample temperature, the opposite happens for interband thermalization. It is demonstrated how, due to the Rashba effect, an interdependence of these timescales on the relative strength of both electron-electron and electron-phonon interactions is responsible for the counterintuitive temperature dependence, with spin-selection constrained interband electron-electron scatterings found both to dominate dynamics away from the Fermi level, and to weaken with increasing temperature. These findings are supported by theoretical calculations within the Boltzmann approach explicitly showing the opposite behavior of all relevant electron-electron and electron-phonon scattering channels with temperature, thus confirming the microscopic mechanism of the experimental findings. The present results are important for future applications of ferroelectric Rashba semiconductors and their excitations in ultrafast spintronics. KW - ferroelectric semiconductors KW - Rashba effect KW - spin- and angle-resolved photoemission KW - spin-orbit coupling KW - time-resolved photoemission KW - ultrafast dynamics Y1 - 2022 U6 - https://doi.org/10.1002/adma.202200323 SN - 0935-9648 SN - 1521-4095 VL - 34 IS - 24 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Culpan, Richard A1 - Geier, Stephan A1 - Reindl, Nicole A1 - Pelisoli, Ingrid A1 - Gentile Fusillo, Nicola Pietro A1 - Vorontseva, Alina T1 - The population of hot subdwarf stars studied with Gaia BT - IV. catalogues of hot subluminous stars based on Gaia EDR3 JF - Astronomy and astrophysics : an international weekly journal N2 - In light of substantial new discoveries of hot subdwarfs by ongoing spectroscopic surveys and the availability of the Gaia mission Early Data Release 3 (EDR3), we compiled new releases of two catalogues of hot subluminous stars: the data release 3 (DR3) catalogue of the known hot subdwarf stars contains 6616 unique sources and provides multi-band photometry, and astrometry from Gaia EDR3 as well as classifications based on spectroscopy and colours. This is an increase of 742 objects over the DR2 catalogue. This new catalogue provides atmospheric parameters for 3087 stars and radial velocities for 2791 stars from the literature. In addition, we have updated the Gaia Data Release 2 (DR2) catalogue of hot subluminous stars using the improved accuracy of the Gaia EDR3 data set together with updated quality and selection criteria to produce the Gaia EDR3 catalogue of 61 585 hot subluminous stars, representing an increase of 21 785 objects. The improvements in Gaia EDR3 astrometry and photometry compared to Gaia DR2 have enabled us to define more sophisticated selection functions. In particular, we improved hot subluminous star detection in the crowded regions of the Galactic plane as well as in the direction of the Magellanic Clouds by including sources with close apparent neighbours but with flux levels that dominate the neighbourhood. KW - subdwarfs KW - Hertzsprung-Russell and C-M diagrams KW - binaries: general KW - stars: horizontal-branch KW - catalogs Y1 - 2022 U6 - https://doi.org/10.1051/0004-6361/202243337 SN - 1432-0746 VL - 662 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Dahlke, Sandro A1 - Solbès, Amélie A1 - Maturilli, Marion T1 - Cold air outbreaks in fram strait: climatology, trends, and observations during an extreme season in 2020 JF - Journal of geophysical research : atmospheres N2 - Fram Strait in the northern North Atlantic is a key region for marine cold air outbreaks (MCAOs), southward discharges of polar air under northerly air flow, which have a strong impact on air-sea heat fluxes, boundary layer processes and severe weather. This study investigates climatologies and decadal trends of Fram Strait MCAOs of different intensity classes based on the ERA5 reanalysis product for 1979-2020. Among striking interannual variability, it is shown that the main MCAO season is December through March, when MCAOs occur around 2/3 of the time. We report on significant decadal MCAO decreases in December and January, and a significant increase in March. While the mid-winter decrease is mainly related to the different paces of warming between the surface and the lower atmosphere, the increase in March can be related to changes in synoptic circulation patterns. As an explanation for the latter, a possible feedback between retreating Barents Sea sea ice, enhanced cyclonic activity and Fram Strait MCAOs is postulated. Exemplifying the trend toward stronger MCAOs during March, the study details the recordbreaking MCAO season in early 2020, and an observational case study of an extreme MCAO event in March 2020 is conducted. Thereby, radiosonde observations are combined with kinematic air back-trajectories to provide rare observational evidence for the diabatic cooling and drying during the MCAO preconditioning phase. KW - cold air outbreak KW - North Atlantic variability KW - air mass transformation; KW - ocean-atmosphere energy exchange Y1 - 2022 U6 - https://doi.org/10.1029/2021JD035741 SN - 2169-897X SN - 2169-8996 VL - 127 IS - 3 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Damle, Mitali A1 - Sparre, Martin A1 - Richter, Philipp A1 - Hani, Maan H. A1 - Nuza, Sebastian A1 - Pfrommer, Christoph A1 - Grand, Robert J. J. A1 - Hoffman, Yehuda A1 - Libeskind, Noam A1 - Sorce, Jenny A1 - Steinmetz, Mathias A1 - Tempel, Elmo A1 - Vogelsberger, Mark A1 - Wang, Peng T1 - Cold and hot gas distribution around the Milky-Way – M31 system in the HESTIA simulations JF - Monthly notices of the royal astronomical society N2 - Recent observations have revealed remarkable insights into the gas reservoir in the circumgalactic medium (CGM) of galaxy haloes. In this paper, we characterise the gas in the vicinity of Milky Way and Andromeda analogues in the hestia (High resolution Environmental Simulations of The Immediate Area) suite of constrained Local Group (LG) simulations. The hestia suite comprise of a set of three high-resolution arepo-based simulations of the LG, run using the Auriga galaxy formation model. For this paper, we focus only on the 𝑧 = 0 simulation datasets and generate mock skymaps along with a power spectrum analysis to show that the distributions of ions tracing low-temperature gas (H i and Si iii) are more clumpy in comparison to warmer gas tracers (O vi, O vii and O viii). We compare to the spectroscopic CGM observations of M31 and low-redshift galaxies. hestia under-produces the column densities of the M31 observations, but the simulations are consistent with the observations of low-redshift galaxies. A possible explanation for these findings is that the spectroscopic observations of M31 are contaminated by gas residing in the CGM of the Milky Way. KW - software: data analysis KW - software: simulations KW - Galaxy: evolution KW - galaxies: evolution KW - galaxies: Local Group Y1 - 2022 U6 - https://doi.org/10.1093/mnras/stac663 SN - 0035-8711 SN - 1365-2966 VL - 512 SP - 3717 EP - 3737 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Deb, Marwan A1 - Molho, Pierre A1 - Barbara, Bernard T1 - Magnetic damping of ferromagnetic and exchange resonance modes in a ferrimagnetic insulator JF - Physical review : B, Condensed matter and materials physics N2 - Understanding the damping is an important fundamental problem with widespread implications in magnetic technology. Ferrimagnetic materials offer a rich platform to explore not only the damping of the ferromagnetic mode, but also the damping of the high-frequency exchange mode very promising for ultrafast devices. Here we use time-resolved magneto-optical Kerr effect to investigate the ferromagnetic and exchange resonance modes and their damping in the bismuth-doped gadolinium iron garnet over a broad range of magnetic fields (0-10 T) and temperatures (50-300 K) including the magnetization and angular compensation points. These two resonance modes are excited via the inverse Faraday effect and unambiguously identified by their distinct frequency dependence on temperature and magnetic field. The temperature-dependent measurements in the external magnetic field H-ext = 2 T revealed that the intrinsic damping of the ferromagnetic mode is always smaller than the one of the exchange modes and both have a maximum near the angular compensation point. These results are fully consistent with recent predictions of atomistic simulations and a theory based on two-sublattice Landau-Lifshitz-Bloch equation. We also demonstrate that the damping of these modes varies differently as a function of H-ext. We explain the observed behaviors by considering the different features of the effective fields defining the precession frequencies of the ferromagnetic and exchange modes. Y1 - 2022 U6 - https://doi.org/10.1103/PhysRevB.105.014432 SN - 2469-9950 SN - 2469-9969 VL - 105 IS - 1 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Deb, Marwan A1 - Popova, Elena A1 - Jaffrès, Henri-Yves A1 - Keller, Niels A1 - Bargheer, Matias T1 - Polarization-dependent subpicosecond demagnetization in iron garnets JF - Physical review : B, covering condensed matter and materials physics N2 - Controlling the magnetization dynamics at the fastest speed is a major issue of fundamental condensed matter physics and its applications for data storage and processing technologies. It requires a deep understanding of the interactions between the degrees of freedom in solids, such as spin, electron, and lattice as well as their responses to external stimuli. In this paper, we systematically investigate the fluence dependence of ultrafast magnetization dynamics induced by below-bandgap ultrashort laser pulses in the ferrimagnetic insulators BixY3-xFe5O12 with 1 xBi 3. We demonstrate subpicosecond demagnetization dynamics in this material followed by a very slow remagnetization process. We prove that this demagnetization results from an ultrafast heating of iron garnets by two-photon absorption (TPA), suggesting a phonon-magnon thermalization time of 0.6 ps. We explain the slow remagnetization timescale by the low phonon heat conductivity in garnets. Additionally, we show that the amplitudes of the demagnetization, optical change, and lattice strain can be manipulated by changing the ellipticity of the pump pulses. We explain this phenomenon considering the TPA circular dichroism. These findings open exciting prospects for ultrafast manipulation of spin, charge, and lattice dynamics in magnetic insulators by ultrafast nonlinear optics. Y1 - 2022 U6 - https://doi.org/10.1103/PhysRevB.106.184416 SN - 2469-9950 SN - 2469-9969 VL - 106 IS - 18 PB - American Institute of Physics, American Physical Society CY - Woodbury, NY ER - TY - JOUR A1 - Deb, Marwan A1 - Popova, Elena A1 - Jaffrès, Henri-Yves A1 - Keller, Niels A1 - Bargheer, Matias T1 - Controlling high-frequency spin-wave dynamics using double-pulse laser excitation JF - Physical review applied N2 - Manipulating spin waves is highly required for the development of innovative data transport and processing technologies. Recently, the possibility of triggering high-frequency standing spin waves in magnetic insulators using femtosecond laser pulses was discovered, raising the question about how one can manipulate their dynamics. Here we explore this question by investigating the ultrafast magnetiza-tion and spin-wave dynamics induced by double-pulse laser excitation. We demonstrate a suppression or enhancement of the amplitudes of the standing spin waves by precisely tuning the time delay between the two pulses. The results can be understood as the constructive or destructive interference of the spin waves induced by the first and second laser pulses. Our findings open exciting perspectives towards generating single-mode standing spin waves that combine high frequency with large amplitude and low magnetic damping. Y1 - 2022 U6 - https://doi.org/10.1103/PhysRevApplied.18.044001 SN - 2331-7019 VL - 18 IS - 4 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Del Corpo, Alfredo A1 - Vellante, Massimo A1 - Zhelavskaya, Irina A1 - Shprits, Yuri Y. A1 - Heilig, Balazs A1 - Reda, Jan A1 - Pietropaolo, Ermanno A1 - Lichtenberger, Janos T1 - Study of the average ion mass of the dayside magnetospheric plasma JF - Journal of geophysical research : Space physics N2 - The investigation of heavy ions dynamics and properties in the Earth's magnetosphere is still an important field of research as they play an important role in several space weather aspects. We present a statistical survey of the average ion mass in the dayside magnetosphere made comparing plasma mass density with electron number density measurements and focusing on both spatial and geomagnetic activity dependence. Field line resonance frequency observations across the European quasi-Meridional Magnetometer Array, are used to infer the equatorial plasma mass density in the range of magnetic L-shells 1.6-6.2. The electron number density is derived from local electric field measurements made on Van Allen Probes using the Neural-network-based Upper-hybrid Resonance Determination algorithm. The analysis is conducted separately for the plasmasphere and the plasmatrough during favorable periods for which both the plasma parameters are observed simultaneously. We found that throughout the plasmasphere the average ion mass is similar or equal to 1 amu for a wide range of geomagnetic activity conditions, suggesting that the plasma mainly consist of hydrogen ions, without regard to the level of geomagnetic activity. Conversely, the plasmatrough is characterized by a variable composition, highlighting a heavy ion mass loading that increases with increasing levels of geomagnetic disturbance. During the most disturbed conditions, the average radial structure shows a broad maximum around 3-4 Earth radii, probably correlated with the accumulation of oxygen ions near the plasmapause. Those ions are mostly observed in the post-dawn and pre-dusk longitudinal sectors. KW - magnetospheric average ion mass KW - magnetospheric plasma spatial KW - distribution KW - oxygen torus KW - geomagnetic activity dependence KW - field line KW - resonances Y1 - 2022 U6 - https://doi.org/10.1029/2022JA030605 SN - 2169-9380 VL - 127 IS - 10 PB - American Geophysical Union CY - Washington, DC ER - TY - JOUR A1 - Diercke, Andrea A1 - Kuckein, Christoph A1 - Cauley, Paul Wilson A1 - Poppenhäger, Katja A1 - Alvarado-Gómez, Julián David A1 - Dineva, Ekaterina Ivanova A1 - Denker, Carsten T1 - Solar H alpha excess during Solar Cycle 24 from full-disk filtergrams of the Chromospheric Telescope JF - Astronomy and astrophysics : an international weekly journal N2 - Context The chromospheric H alpha spectral line is a strong line in the spectrum of the Sun and other stars. In the stellar regime, this spectral line is already used as a powerful tracer of stellar activity. For the Sun, other tracers, such as Ca II K, are typically used to monitor solar activity. Nonetheless, the Sun is observed constantly in H alpha with globally distributed ground-based full-disk imagers. Aims The aim of this study is to introduce the imaging H alpha excess and deficit as tracers of solar activity and compare them to other established indicators. Furthermore, we investigate whether the active region coverage fraction or the changing H alpha excess in the active regions dominates temporal variability in solar H alpha observations. Methods We used observations of full-disk H alpha filtergrams of the Chromospheric Telescope and morphological image processing techniques to extract the imaging H alpha excess and deficit, which were derived from the intensities above or below 10% of the median intensity in the filtergrams, respectively. These thresholds allowed us to filter for bright features (plage regions) and dark absorption features (filaments and sunspots). In addition, the thresholds were used to calculate the mean intensity I-mean(E/D) for H alpha excess and deficit regions. We describe the evolution of the H alpha excess and deficit during Solar Cycle 24 and compare it to the mean intensity and other well established tracers: the relative sunspot number, the F10.7 cm radio flux, and the Mg II index. In particular, we tried to determine how constant the H alpha excess and number density of H alpha excess regions are between solar maximum and minimum. The number of pixels above or below the intensity thresholds were used to calculate the area coverage fraction of H alpha excess and deficit regions on the Sun, which was compared to the imaging H alpha excess and deficit and the respective mean intensities averaged for the length of one Carrington rotation. In addition, we present the H alpha excess and mean intensity variation of selected active regions during their disk passage in comparison to the number of pixels of H alpha excess regions. Results. The H alpha excess and deficit follow the behavior of the solar activity over the course of the cycle. They both peak around solar maximum, whereby the peak of the H alpha deficit is shortly after the solar maximum. Nonetheless, the correlation of the monthly averages of the H alpha excess and deficit is high with a Spearman correlation of rho =  0.91. The H alpha excess is closely correlated to the chromospheric Mg II index with a correlation of 0.95. The highest correlation of the H alpha deficit is found with the F10.7 cm radio flux, with a correlation of 0.89, due to their peaks after the solar activity maximum. Furthermore, the H alpha deficit reflects the cyclic behavior of polar crown filaments and their disappearance shortly before the solar maximum. We investigated the mean intensity distribution for H alpha excess regions for solar minimum and maximum. The shape of the distributions for solar minimum and maximum is very similar, but with different amplitudes. Furthermore, we found that the area coverage fraction of H alpha excess regions and the H alpha excess are strongly correlated with an overall Spearman correlation of 0.92. The correlation between the H alpha excess and the mean intensity of H alpha excess regions is 0.75. The correlation of the area coverage fraction and the mean intensity of H alpha excess regions is in general relatively low (rho = 0.45) and only for few active regions is this correlation above 0.7. The weak correlation between the area coverage fraction and mean intensity leaves us pessimistic that the degeneracy between these two quantities can be broken for the modeling of unresolved stellar surfaces. KW - methods: observational KW - Sun: chromosphere KW - Sun: activity KW - Sun: faculae, plages KW - Sun: filaments KW - stars: atmospheres KW - prominences Y1 - 2022 U6 - https://doi.org/10.1051/0004-6361/202040091 SN - 1432-0746 SN - 0004-6361 VL - 661 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Dieterich, Peter A1 - Lindemann, Otto A1 - Moskopp, Mats Leif A1 - Tauzin, Sebastien A1 - Huttenlocher, Anna A1 - Klages, Rainer A1 - Chechkin, Aleksei V. A1 - Schwab, Albrecht T1 - Anomalous diffusion and asymmetric tempering memory in neutrophil chemotaxis JF - PLoS Computational Biology : a new community journal N2 - Neutrophil granulocytes are essential for the first host defense. After leaving the blood circulation they migrate efficiently towards sites of inflammation. They are guided by chemoattractants released from cells within the inflammatory foci. On a cellular level, directional migration is a consequence of cellular front-rear asymmetry which is induced by the concentration gradient of the chemoattractants. The generation and maintenance of this asymmetry, however, is not yet fully understood. Here we analyzed the paths of chemotacting neutrophils with different stochastic models to gain further insight into the underlying mechanisms. Wildtype chemotacting neutrophils show an anomalous superdiffusive behavior. CXCR2 blockade and TRPC6-knockout cause the tempering of temporal correlations and a reduction of chemotaxis. Importantly, such tempering is found both in vitro and in vivo. These findings indicate that the maintenance of anomalous dynamics is crucial for chemotactic behavior and the search efficiency of neutrophils. The motility of neutrophils and their ability to sense and to react to chemoattractants in their environment are of central importance for the innate immunity. Neutrophils are guided towards sites of inflammation following the activation of G-protein coupled chemoattractant receptors such as CXCR2 whose signaling strongly depends on the activity of Ca2+ permeable TRPC6 channels. It is the aim of this study to analyze data sets obtained in vitro (murine neutrophils) and in vivo (zebrafish neutrophils) with a stochastic mathematical model to gain deeper insight into the underlying mechanisms. The model is based on the analysis of trajectories of individual neutrophils. Bayesian data analysis, including the covariances of positions for fractional Brownian motion as well as for exponentially and power-law tempered model variants, allows the estimation of parameters and model selection. Our model-based analysis reveals that wildtype neutrophils show pure superdiffusive fractional Brownian motion. This so-called anomalous dynamics is characterized by temporal long-range correlations for the movement into the direction of the chemotactic CXCL1 gradient. Pure superdiffusion is absent vertically to this gradient. This points to an asymmetric 'memory' of the migratory machinery, which is found both in vitro and in vivo. CXCR2 blockade and TRPC6-knockout cause tempering of temporal correlations in the chemotactic gradient. This can be interpreted as a progressive loss of memory, which leads to a marked reduction of chemotaxis and search efficiency of neutrophils. In summary, our findings indicate that spatially differential regulation of anomalous dynamics appears to play a central role in guiding efficient chemotactic behavior. KW - neutrophils KW - chemotaxis KW - autocorrelation KW - zebrafish KW - cell migration KW - covariance KW - brownian motion KW - stochastic processes Y1 - 2022 U6 - https://doi.org/10.1371/journal.pcbi.1010089 SN - 1553-734X SN - 1553-7358 VL - 18 IS - 5 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Dineva, Ekaterina Ivanova A1 - Pearson, Jeniveve A1 - Ilyin, Ilya A1 - Verma, Meetu A1 - Diercke, Andrea A1 - Strassmeier, Klaus A1 - Denker, Carsten T1 - Characterization of chromospheric activity based on Sun-as-a-star spectral and disk-resolved activity indices JF - Astronomische Nachrichten = Astronomical notes N2 - The strong chromospheric absorption lines Ca ii H & K are tightly connected to stellar surface magnetic fields. Only for the Sun, spectral activity indices can be related to evolving magnetic features on the solar disk. The Solar Disk-Integrated (SDI) telescope feeds the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) of the Large Binocular Telescope (LBT) at Mt. Graham International Observatory, Arizona, U.S.A. We present high-resolution, high-fidelity spectra that were recorded on 184 & 82 days in 2018 & 2019 and derive the Ca ii H & K emission ratio, that is, the S-index. In addition, we compile excess brightness and area indices based on full-disk Ca ii K-line-core filtergrams of the Chromospheric Telescope (ChroTel) at Observatorio del Teide, Tenerife, Spain and full-disk ultraviolet (UV) 1600 angstrom images of the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). Thus, Sun-as-a-star spectral indices are related to their counterparts derived from resolved images of the solar chromosphere. All indices display signatures of rotational modulation, even during the very low magnetic activity in the minimum of Solar Cycle 24. Bringing together different types of activity indices has the potential to join disparate chromospheric datasets yielding a comprehensive description of chromospheric activity across many solar cycles. KW - astronomical databases KW - miscellaneous KW - methods KW - data analysis KW - activity KW - Sun KW - atmosphere KW - chromosphere KW - techniques KW - spectroscopic Y1 - 2022 U6 - https://doi.org/10.1002/asna.20223996 SN - 0004-6337 SN - 1521-3994 VL - 343 IS - 5 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Doerries, Timo J. A1 - Chechkin, Aleksei A1 - Schumer, Rina A1 - Metzler, Ralf T1 - Rate equations, spatial moments, and concentration profiles for mobile-immobile models with power-law and mixed waiting time distributions JF - Physical review : E, Statistical, nonlinear and soft matter physics N2 - We present a framework for systems in which diffusion-advection transport of a tracer substance in a mobile zone is interrupted by trapping in an immobile zone. Our model unifies different model approaches based on distributed-order diffusion equations, exciton diffusion rate models, and random-walk models for multirate mobile-immobile mass transport. We study various forms for the trapping time dynamics and their effects on the tracer mass in the mobile zone. Moreover, we find the associated breakthrough curves, the tracer density at a fixed point in space as a function of time, and the mobile and immobile concentration profiles and the respective moments of the transport. Specifically, we derive explicit forms for the anomalous transport dynamics and an asymptotic power-law decay of the mobile mass for a Mittag-Leffler trapping time distribution. In our analysis we point out that even for exponential trapping time densities, transient anomalous transport is observed. Our results have direct applications in geophysical contexts, but also in biological, soft matter, and solid state systems. Y1 - 2022 U6 - https://doi.org/10.1103/PhysRevE.105.014105 SN - 2470-0045 SN - 2470-0053 VL - 105 IS - 1 PB - The American Institute of Physics CY - Woodbury, NY ER - TY - JOUR A1 - Doerries, Timo J. A1 - Chechkin, Aleksei V. A1 - Metzler, Ralf T1 - Apparent anomalous diffusion and non-Gaussian distributions in a simple mobile-immobile transport model with Poissonian switching JF - Interface : journal of the Royal Society N2 - We analyse mobile-immobile transport of particles that switch between the mobile and immobile phases with finite rates. Despite this seemingly simple assumption of Poissonian switching, we unveil a rich transport dynamics including significant transient anomalous diffusion and non-Gaussian displacement distributions. Our discussion is based on experimental parameters for tau proteins in neuronal cells, but the results obtained here are expected to be of relevance for a broad class of processes in complex systems. Specifically, we obtain that, when the mean binding time is significantly longer than the mean mobile time, transient anomalous diffusion is observed at short and intermediate time scales, with a strong dependence on the fraction of initially mobile and immobile particles. We unveil a Laplace distribution of particle displacements at relevant intermediate time scales. For any initial fraction of mobile particles, the respective mean squared displacement (MSD) displays a plateau. Moreover, we demonstrate a short-time cubic time dependence of the MSD for immobile tracers when initially all particles are immobile. KW - diffusion KW - mobile-immobile model KW - tau proteins Y1 - 2022 U6 - https://doi.org/10.1098/rsif.2022.0233 SN - 1742-5689 SN - 1742-5662 VL - 19 IS - 192 PB - Royal Society CY - London ER - TY - JOUR A1 - Drechsler, Martin A1 - Wätzold, Frank A1 - Grimm, Volker T1 - The hitchhiker's guide to generic ecological-economic modelling of land-use-based biodiversity conservation policies JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog N2 - Biodiversity loss is a result of interacting ecological and economic factors, and it must be addressed through an analysis of biodiversity conservation policies. Ecological-economic modelling is a helpful approach to this analysis, but it is also challenging since modellers often have a specific disciplinary background and tend to misrepresent either the ecological or economic aspects. Here, we introduce some of the most important concepts from both disciplines, and since the two modelling cultures also differ between the two disciplines, we present an integrated, consistent guide through all the steps of generic ecological-economic modelling, such as formulation of the research question, development of the conceptual model, model parametrisation and analysis, and interpretation of model results. Although we focus on generic models aimed at a general understanding of causes and remedies for biodiversity loss, the concepts and guidance provided here may also help in the modelling of more specific conservation problems. This guide is aimed at the intersection of three disciplines: ecology, economics and mathematical modelling, and addresses readers who have some knowledge in at least one of these disciplines and want to learn about the others to build and analyse generic ecological-economic models. Compared to textbooks, the guide focuses on the practice of modelling rather than lengthy explanations of theoretical concepts. We attempt to demonstrate that generic ecological-economic modelling does not require magical powers and instead is a manageable exercise. KW - Biodiversity KW - Conservation policy KW - Ecological-economic modelling KW - Generic modelling KW - Land use Y1 - 2022 U6 - https://doi.org/10.1016/j.ecolmodel.2021.109861 SN - 0304-3800 SN - 1872-7026 VL - 465 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Drozdov, Alexander A1 - Allison, Hayley J. A1 - Shprits, Yuri Y. A1 - Usanova, Maria E. A1 - Saikin, Anthony A1 - Wang, Dedong T1 - Depletions of Multi-MeV Electrons and their association to Minima in Phase Space Density JF - Geophysical research letters N2 - Fast-localized electron loss, resulting from interactions with electromagnetic ion cyclotron (EMIC) waves, can produce deepening minima in phase space density (PSD) radial profiles. Here, we perform a statistical analysis of local PSD minima to quantify how readily these are associated with radiation belt depletions. The statistics of PSD minima observed over a year are compared to the Versatile Electron Radiation Belts (VERB) simulations, both including and excluding EMIC waves. The observed minima distribution can only be achieved in the simulation including EMIC waves, indicating their importance in the dynamics of the radiation belts. By analyzing electron flux depletions in conjunction with the observed PSD minima, we show that, in the heart of the outer radiation belt (L* < 5), on average, 53% of multi-MeV electron depletions are associated with PSD minima, demonstrating that fast localized loss by interactions with EMIC waves are a common and crucial process for ultra-relativistic electron populations. KW - radiation belts KW - EMIC KW - VERB KW - PSD Y1 - 2022 U6 - https://doi.org/10.1029/2021GL097620 SN - 0094-8276 SN - 1944-8007 VL - 49 IS - 8 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Dudi, Reetika A1 - Adhikari, Ananya A1 - Brügmann, Bernd A1 - Dietrich, Tim A1 - Hayashi, Kota A1 - Kawaguchi, Kyohei A1 - Kiuchi, Kenta A1 - Kyutoku, Koutarou A1 - Shibata, Masaru A1 - Tichy, Wolfgang T1 - Investigating GW190425 with numerical-relativity simulations JF - Physical review : D, Particles, fields, gravitation, and cosmology N2 - The third observing run of the LIGO-Virgo Collaboration has resulted in many gravitational wave detections, including the binary neutron star merger GW190425. However, none of these events have been accompanied with an electromagnetic transient found during extensive follow-up searches. In this article, we perform new numerical-relativity simulations of binary neutron star and black hole-neutron star systems that have a chirp mass consistent with GW190425. Assuming that the GW190425's sky location was covered with sufficient accuracy during the electromagnetic follow-up searches, we investigate whether the nondetection of the kilonova is compatible with the source parameters estimated through the gravitational -wave analysis and how one can use this information to place constraints on the properties of the system. Our simulations suggest that GW190425 is incompatible with an unequal mass binary neutron star merger with a mass ratio q < 0.8 when considering stiff or moderately stiff equations of state if the binary was face on and covered by the observation. Our analysis shows that a detailed observational result for kilonovae will be useful to constrain the mass ratio of binary neutron stars in future events. Y1 - 2022 U6 - https://doi.org/10.1103/PhysRevD.106.084039 SN - 2470-0010 SN - 2470-0029 VL - 106 IS - 8 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Dudi, Reetika A1 - Dietrich, Tim A1 - Rashti, Alireza A1 - Brügmann, Bernd A1 - Steinhoff, Jan A1 - Tichy, Wolfgang T1 - High-accuracy simulations of highly spinning binary neutron star systems JF - Physical review : D, Particles, fields, gravitation, and cosmology N2 - With an increasing number of expected gravitational-wave detections of binary neutron star mergers, it is essential that gravitational-wave models employed for the analysis of observational data are able to describe generic compact binary systems. This includes systems in which the individual neutron stars are millisecond pulsars for which spin effects become essential. In this work, we perform numerical-relativity simulations of binary neutron stars with aligned and antialigned spins within a range of dimensionless spins of chi similar to [-0.28, 0.58]. The simulations are performed with multiple resolutions, show a clear convergence order and, consequently, can be used to test existing waveform approximants. We find that for very high spins gravitational-wave models that have been employed for the interpretation of GW170817 and GW190425 arc not capable of describing our numerical-relativity dataset. We verify through a full parameter estimation study in which clear biases in the estimate of the tidal deformability and effective spin are present. We hope that in preparation of the next gravitational-wave observing run of the Advanced LIGO and Advanced Virgo detectors our new set of numerical-relativity data can be used to support future developments of new gravitational-wave models. Y1 - 2022 U6 - https://doi.org/10.1103/PhysRevD.105.064050 SN - 2470-0010 SN - 2470-0029 VL - 105 IS - 6 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Eckert, Sebastian A1 - Mascarenhas, Eric Johnn A1 - Mitzner, Rolf A1 - Jay, Raphael Martin A1 - Pietzsch, Annette A1 - Fondell, Mattis A1 - Vaz da Cruz, Vinicius A1 - Föhlisch, Alexander T1 - From the free ligand to the transition metal complex BT - FeEDTA(-) formation seen at ligand K-Edges JF - Inorganic chemistry N2 - Chelating agents are an integral part of transition metal complex chemistry with broad biological and industrial relevance. The hexadentate chelating agent ethylenediaminetetraacetic acid (EDTA) has the capability to bind to metal ions at its two nitrogen and four of its carboxylate oxygen sites. We use resonant inelastic X-ray scattering at the 1s absorption edge of the aforementioned elements in EDTA and the iron(III)-EDTA complex to investigate the impact of the metal-ligand bond formation on the electronic structure of EDTA. Frontier orbital distortions, occupation changes, and energy shifts through metal- ligand bond formation are probed through distinct spectroscopic signatures. KW - Energy KW - Ligands KW - Metals KW - Nitrogen KW - Oxygen Y1 - 2022 U6 - https://doi.org/10.1021/acs.inorgchem.2c00789 SN - 0020-1669 SN - 1520-510X VL - 61 IS - 27 SP - 10321 EP - 10328 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Emma, Mattia A1 - Schianchi, Federico A1 - Pannarale, Francesco A1 - Sagun, Violetta A1 - Dietrich, Tim T1 - Numerical simulations of dark matter admixed neutron star binaries JF - Particles N2 - Multi-messenger observations of compact binary mergers provide a new way to constrain the nature of dark matter that may accumulate in and around neutron stars. In this article, we extend the infrastructure of our numerical-relativity code BAM to enable the simulation of neutron stars that contain an additional mirror dark matter component. We perform single star tests to verify our code and the first binary neutron star simulations of this kind. We find that the presence of dark matter reduces the lifetime of the merger remnant and favors a prompt collapse to a black hole. Furthermore, we find differences in the merger time for systems with the same total mass and mass ratio, but different amounts of dark matter. Finally, we find that electromagnetic signals produced by the merger of binary neutron stars admixed with dark matter are very unlikely to be as bright as their dark matter-free counterparts. Given the increased sensitivity of multi-messenger facilities, our analysis gives a new perspective on how to probe the presence of dark matter. KW - numerical relativity KW - dark matter KW - neutron stars KW - equation of state; KW - gravitational-wave astronomy KW - multi-messenger astrophysics Y1 - 2022 U6 - https://doi.org/10.3390/particles5030024 SN - 2571-712X VL - 5 IS - 3 SP - 273 EP - 286 PB - MDPI CY - Basel ER - TY - JOUR A1 - Feldmann, Johannes A1 - Reese, Ronja A1 - Winkelmann, Ricarda A1 - Levermann, Anders T1 - Shear-margin melting causes stronger transient ice discharge than ice-stream melting in idealized simulations JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union N2 - Basal ice-shelf melting is the key driver of Antarctica's increasing sea-level contribution. In diminishing the buttressing force of the ice shelves that fringe the ice sheet, the melting increases the ice discharge into the ocean. Here we contrast the influence of basal melting in two different ice-shelf regions on the time-dependent response of an isothermal, inherently buttressed ice-sheet-shelf system. In the idealized numerical simulations, the basal-melt perturbations are applied close to the grounding line in the ice-shelf's (1) ice-stream region, where the ice shelf is fed by the fastest ice masses that stream through the upstream bed trough and (2) shear margins, where the ice flow is slower. The results show that melting below one or both of the shear margins can cause a decadal to centennial increase in ice discharge that is more than twice as large compared to a similar perturbation in the ice-stream region. We attribute this to the fact that melt-induced ice-shelf thinning in the central grounding-line region is attenuated very effectively by the fast flow of the central ice stream. In contrast, the much slower ice dynamics in the lateral shear margins of the ice shelf facilitate sustained ice-shelf thinning and thereby foster buttressing reduction. Regardless of the melt location, a higher melt concentration toward the grounding line generally goes along with a stronger response. Our results highlight the vulnerability of outlet glaciers to basal melting in stagnant, buttressing-relevant ice-shelf regions, a mechanism that may gain importance under future global warming. Y1 - 2022 U6 - https://doi.org/10.5194/tc-16-1927-2022 SN - 1994-0416 SN - 1994-0424 VL - 16 IS - 5 SP - 1927 EP - 1940 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Fischer, Eric W. A1 - Saalfrank, Peter T1 - Cavity-induced non-adiabatic dynamics and spectroscopy of molecular rovibrational polaritons studied by multi-mode quantum models JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - We study theoretically the quantum dynamics and spectroscopy of rovibrational polaritons formed in a model system composed of a single rovibrating diatomic molecule, which interacts with two degenerate, orthogonally polarized modes of an optical Fabry-Perot cavity. We employ an effective rovibrational Pauli-Fierz Hamiltonian in length gauge representation and identify three-state vibro-polaritonic conical intersections (VPCIs) between singly excited vibro-polaritonic states in a two-dimensional angular coordinate branching space. The lower and upper vibrational polaritons are of mixed light-matter hybrid character, whereas the intermediate state is purely photonic in nature. The VPCIs provide effective population transfer channels between singly excited vibrational polaritons, which manifest in rich interference patterns in rotational densities. Spectroscopically, three bright singly excited states are identified when an external infrared laser field couples to both a molecular and a cavity mode. The non-trivial VPCI topology manifests as pronounced multi-peak progression in the spectral region of the upper vibrational polariton, which is traced back to the emergence of rovibro-polaritonic light-matter hybrid states. Experimentally, ubiquitous spontaneous emission from cavity modes induces a dissipative reduction of intensity and peak broadening, which mainly influences the purely photonic intermediate state peak as well as the rovibro-polaritonic progression. Published under an exclusive license by AIP Publishing. Y1 - 2022 U6 - https://doi.org/10.1063/5.0098006 SN - 0021-9606 SN - 1089-7690 VL - 157 IS - 3 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Fischer, Eric Wolfgang A1 - Anders, Janet A1 - Saalfrank, Peter T1 - Cavity-altered thermal isomerization rates and dynamical resonant localization in vibro-polaritonic chemistry JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - It has been experimentally demonstrated that reaction rates for molecules embedded in microfluidic optical cavities are altered when compared to rates observed under "ordinary" reaction conditions. However, precise mechanisms of how strong coupling of an optical cavity mode to molecular vibrations affects the reactivity and how resonance behavior emerges are still under dispute. In the present work, we approach these mechanistic issues from the perspective of a thermal model reaction, the inversion of ammonia along the umbrella mode, in the presence of a single-cavity mode of varying frequency and coupling strength. A topological analysis of the related cavity Born-Oppenheimer potential energy surface in combination with quantum mechanical and transition state theory rate calculations reveals two quantum effects, leading to decelerated reaction rates in qualitative agreement with experiments: the stiffening of quantized modes perpendicular to the reaction path at the transition state, which reduces the number of thermally accessible reaction channels, and the broadening of the barrier region, which attenuates tunneling. We find these two effects to be very robust in a fluctuating environment, causing statistical variations of potential parameters, such as the barrier height. Furthermore, by solving the time-dependent Schrodinger equation in the vibrational strong coupling regime, we identify a resonance behavior, in qualitative agreement with experimental and earlier theoretical work. The latter manifests as reduced reaction probability when the cavity frequency omega(c) is tuned resonant to a molecular reactant frequency. We find this effect to be based on the dynamical localization of the vibro-polaritonic wavepacket in the reactant well. Y1 - 2022 U6 - https://doi.org/10.1063/5.0076434 SN - 0021-9606 SN - 1089-7690 VL - 156 IS - 15 PB - American Institute of Physics CY - Melville, NY ER - TY - JOUR A1 - Foster, Grace A1 - Poppenhäger, Katja T1 - Identifying interesting planetary systems for future X-ray observations JF - Astronomische Nachrichten = Astronomical notes N2 - X-ray observations of star-planet systems are important to grow our understanding of exoplanets; these observations allow for studies of photoevaporation of the exoplanetary atmosphere, and in some cases even estimations of the size of the outer planetary atmosphere. The German-Russian eROSITA instrument onboard the SRG (Spectrum Roentgen Gamma) mission is performing the first all-sky X-ray survey since the 1990s, and provides X-ray fluxes and spectra of exoplanet host stars over a much larger volume than was accessible before. Using new eROSITA data as well as archival data from XMM-Newton, Chandra, and ROSAT, we estimate mass-loss rates of exoplanets under an energy-limited escape scenario and identify several exoplanets with strong X-ray irradiation and expected mass loss that are amenable to follow-up observations at other wavelengths. We model sample spectra using a toy model of an exoplanetary atmosphere to predict what exoplanet transit observations with future X-ray missions such as Athena will look like and estimate the observable X-ray transmission spectrum for a typical hot Jupiter-type exoplanet. KW - planets and satellites KW - general KW - stars KW - activity KW - coronae KW - planetary systems KW - X-rays Y1 - 2022 U6 - https://doi.org/10.1002/asna.20220007 SN - 1521-3994 VL - 343 IS - 4 PB - Wiley-VCH CY - Berlin ER - TY - THES A1 - Foster, Mary Grace T1 - X-Ray studies of exoplanet systems N2 - X-rays are integral to furthering our knowledge of exoplanetary systems. In this work we discuss the use of X-ray observations to understand star-planet interac- tions, mass-loss rates of an exoplanet’s atmosphere and the study of an exoplanet’s atmospheric components using future X-ray spectroscopy. The low-mass star GJ 1151 was reported to display variable low-frequency radio emission, which is an indication of coronal star-planet interactions with an unseen exoplanet. In chapter 5 we report the first X-ray detection of GJ 1151’s corona based on XMM-Newton data. Averaged over the observation, we detect the star with a low coronal temperature of 1.6 MK and an X-ray luminosity of LX = 5.5 × 1026 erg/s. This is compatible with the coronal assumptions for a sub-Alfvénic star- planet interaction origin of the observed radio signals from this star. In chapter 6, we aim to characterise the high-energy environment of known ex- oplanets and estimate their mass-loss rates. This work is based on the soft X-ray instrument on board the Spectrum Roentgen Gamma (SRG) mission, eROSITA, along with archival data from ROSAT, XMM-Newton, and Chandra. We use these four X-ray source catalogues to derive X-ray luminosities of exoplanet host stars in the 0.2-2 keV energy band. A catalogue of the mass-loss rates of 287 exoplan- ets is presented, with 96 of these planets characterised for the first time using new eROSITA detections. Of these first time detections, 14 are of transiting exoplanets that undergo irradiation from their host stars that is of a level known to cause ob- servable evaporation signals in other systems, making them suitable for follow-up observations. In the next generation of space observatories, X-ray transmission spectroscopy of an exoplanet’s atmosphere will be possible, allowing for a detailed look into the atmospheric composition of these planets. In chapter 7, we model sample spectra using a toy model of an exoplanetary atmosphere to predict what exoplanet transit observations with future X-ray missions such as Athena will look like. We then estimate the observable X-ray transmission spectrum for a typical Hot Jupiter-type exoplanet, giving us insights into the advances in X-ray observations of exoplanets in the decades to come. N2 - Röntgenstrahlen sind ein wesentlicher Bestandteil, um unser Wissen über extrasolare Planetensysteme zu vertiefen und zu erweitern. In dieser Arbeit erörtern wir den Einsatz von Röntgenbeobachtungen zum Verständnis von Stern-Planeten-Interaktionen, der Abschätzung von Massenverlustraten von Exoplanetenatmosphären und die Untersuchung der atmosphärischen Komponenten eines Exoplaneten mithilfe zukünftiger Röntgenspektroskopie. Beobachtungen des massearmen Sterns GJ 1151 deuten auf eine variable Emission niederfrequenter Radiostrahlung hin, was als Indiz für koronale Stern-Planeten-Wechselwirkungen mit einem unsichtbaren Exoplaneten angesehen wird. In Kapitel 5 berichten wir über den ersten Röntgennachweis der Korona von GJ 1151, basierend auf XMM-Newton Daten. Über die gesamte Beobachtungsdauer gemittelt, weisen wir den Stern mit einer niedrigen koronalen Temperatur von 1,6 MK und einer Röntgenluminosität von LX = 5, 5 ◊ 1026 erg/s nach. Dieser Nachweis im Röntgenlicht ist kompatibel mit der Annahme, dass sub-Alfvénische Wechselwirkungen zwischen stellarer Corona und Exoplanet die Ursache für die beobachteten Radiosignale des Sterns sind. Kapitel 6 zielt darauf ab, die hochenergetische Umgebung bekannter Exoplaneten zu charakterisieren und die Massenverlustraten der Planetenatmosphären abzuschätzen. Diese Arbeit basiert auf neu gewonnenen Daten des Instruments für weiche Röntgenstrahlung an Bord der Spectrum Roentgen Gamma (SRG) Mission, eROSITA, und wird komplementiert von Archivdaten von ROSAT, XMM-Newton und Chandra. Mithilfe dieser vier Röntgenquellenkataloge vermessen wir die Röntgenhelligkeit der Zentralsterne von bekannten Exoplanetensytemen im Energiebereich von 0,2-2 keV. Die Ergebnisse sind zusammen mit den errechneten Massenverlustraten von 287 Exoplaneten in einem Katalog zusammengefasst, darunter 96 Planeten, die zum ersten Mal durch neue eROSITA-Nachweise charakterisiert wurden. Bei 14 dieser Erstnachweise handelt es sich um transitierende Exoplaneten, die von ihrem Heimatstern so stark bestrahlt werden, dass beobachtbare Signale, ausgelöst durch die Verdampfung ihrer Atmosphäre, zu erwarten sind. Speziell diese Systeme eignen sich besonders für Folgebeobachtungen. Mit der nächsten Generation von Weltraumobservatorien wird die Röntgentransmissionsspektroskopie von extrasolaren Planetenatmosphären möglich sein, was nie dagewesene Details über die atmosphärische Zusammensetzung dieser Planeten ans Licht bringen wird. In Kapitel 7 modellieren wir Transmissionsspektren mithilfe eines vereinfachten Modells einer Exoplanetenatmosphäre um vorherzusagen, wie Transitbeobachtungen von Exoplaneten mit zukünftigen Röntgenmissionen wie Athena aussehen werden. Wir schätzen dann das beobachtbare Röntgentransmissionsspektrum für einen typischen Exoplaneten vom Typ Hot Jupiter ab, was uns einen Einblick in die zu erwartenden Fortschritte bei der Röntgenbeobachtung von Exoplaneten in den kommenden Jahrzehnten gibt. KW - exoplanets KW - x-rays KW - stellar physics KW - Exoplaneten KW - Röntgenstrahlen KW - stellare Physik Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-562152 PB - xiii, 92 ER - TY - JOUR A1 - Foster, Mary Grace A1 - Poppenhäger, Katja A1 - Ilić Petković, Nikoleta A1 - Schwope, Axel T1 - Exoplanet X-ray irradiation and evaporation rates with eROSITA JF - Astronomy and astrophysics : an international weekly journal N2 - High-energy irradiation is a driver for atmospheric evaporation and mass loss in exoplanets. This work is based on data from eROSITA, the soft X-ray instrument on board the Spectrum Roentgen Gamma mission, as well as on archival data from other missions. We aim to characterise the high-energy environment of known exoplanets and estimate their mass-loss rates. We use X-ray source catalogues from eROSITA, XMM-Newton, Chandra, and ROSAT to derive X-ray luminosities of exoplanet host stars in the 0.2–2 keV energy band with an underlying coronal, that is, optically thin thermal spectrum. We present a catalogue of stellar X-ray and EUV luminosities, exoplanetary X-ray and EUV irradiation fluxes, and estimated mass-loss rates for a total of 287 exoplanets, 96 of which are characterised for the first time based on new eROSITA detections. We identify 14 first-time X-ray detections of transiting exoplanets that are subject to irradiation levels known to cause observable evaporation signatures in other exoplanets. This makes them suitable targets for follow-up observations. KW - stars: coronae KW - stars: activity KW - planet-star interactions KW - planets and KW - satellites: atmospheres KW - X-rays: stars Y1 - 2022 U6 - https://doi.org/10.1051/0004-6361/202141097 SN - 0004-6361 SN - 1432-0746 VL - 661 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Fritsch, Daniel T1 - Revisiting the Cu-Zn disorder in kesterite type Cu2ZnSnSe4 employing a novel approach to hybrid functional calculations JF - Applied Sciences : open access journal N2 - In recent years, the search for more efficient and environmentally friendly materials to be employed in the next generation of thin film solar cell devices has seen a shift towards hybrid halide perovskites and chalcogenide materials crystallising in the kesterite crystal structure. Prime examples for the latter are Cu2ZnSnS4, Cu2ZnSnSe4, and their solid solution Cu2ZnSn(SxSe1-x)(4), where actual devices already demonstrated power conversion efficiencies of about 13 %. However, in their naturally occurring kesterite crystal structure, the so-called Cu-Zn disorder plays an important role and impacts the structural, electronic, and optical properties. To understand the influence of Cu-Zn disorder, we perform first-principles calculations based on density functional theory combined with special quasirandom structures to accurately model the cation disorder. Since the electronic band gaps and derived optical properties are severely underestimated by (semi)local exchange and correlation functionals, supplementary hybrid functional calculations have been performed. Concerning the latter, we additionally employ a recently devised technique to speed up structural relaxations for hybrid functional calculations. Our calculations show that the Cu-Zn disorder leads to a slight increase in the unit cell volume compared to the conventional kesterite structure showing full cation order, and that the band gap gets reduced by about 0.2 eV, which is in very good agreement with earlier experimental and theoretical findings. Our detailed results on structural, electronic, and optical properties will be discussed with respect to available experimental data, and will provide further insights into the atomistic origin of the disorder-induced band gap lowering in these promising kesterite type materials. KW - Cu2ZnSnSe4 KW - CZTSe KW - chalcogenide KW - kesterite KW - Cu-Zn disorder KW - density KW - functional theory KW - hybrid functional KW - special quasirandom structure Y1 - 2022 U6 - https://doi.org/10.3390/app12052576 SN - 2076-3417 VL - 12 IS - 5 PB - MDPI CY - Basel ER - TY - JOUR A1 - Fritsch, Tobias A1 - Kurpiers, Jona A1 - Roland, Steffen A1 - Tokmoldin, Nurlan A1 - Shoaee, Safa A1 - Ferron, Thomas A1 - Collins, Brian A. A1 - Janietz, Silvia A1 - Vandewal, Koen A1 - Neher, Dieter T1 - On the interplay between CT and singlet exciton emission in organic solar cells with small driving force and its impact on voltage loss JF - Advanced energy materials N2 - The interplay between free charge carriers, charge transfer (CT) states and singlet excitons (S-1) determines the recombination pathway and the resulting open circuit voltage (V-OC) of organic solar cells. By combining a well-aggregated low bandgap polymer with different blend ratios of the fullerenes PCBM and ICBA, the energy of the CT state (E-CT) is varied by 130 meV while leaving the S-1 energy of the polymer (ES1\[{E_{{{\rm{S}}_1}}}\]) unaffected. It is found that the polymer exciton dominates the radiative properties of the blend when ECT\[{E_{{\rm{CT}}}}\] approaches ES1\[{E_{{{\rm{S}}_1}}}\], while the V-OC remains limited by the non-radiative decay of the CT state. It is concluded that an increasing strength of the exciton in the optical spectra of organic solar cells will generally decrease the non-radiative voltage loss because it lowers the radiative V-OC limit (V-OC,V-rad), but not because it is more emissive. The analysis further suggests that electronic coupling between the CT state and the S-1 will not improve the V-OC, but rather reduce the V-OC,V-rad. It is anticipated that only at very low CT state absorption combined with a fairly high CT radiative efficiency the solar cell benefit from the radiative properties of the singlet excitons. KW - external quantum efficiency KW - organic photovoltaics KW - ternary blends KW - voltage losses Y1 - 2022 U6 - https://doi.org/10.1002/aenm.202200641 SN - 1614-6832 SN - 1614-6840 VL - 12 IS - 31 PB - Wiley-VCH CY - Weinheim ER - TY - THES A1 - Förste, Stefanie T1 - Assemblierung von Proteinkomplexen in vitro und in vivo T1 - Assembly of protein complexes in vitro and in vivo N2 - Proteine sind an praktisch allen Prozessen in lebenden Zellen maßgeblich beteiligt. Auch in der Biotechnologie werden Proteine in vielfältiger Weise eingesetzt. Ein Protein besteht aus einer Kette von Aminosäuren. Häufig lagern sich mehrere dieser Ketten zu größeren Strukturen und Funktionseinheiten, sogenannten Proteinkomplexen, zusammen. Kürzlich wurde gezeigt, dass eine Proteinkomplexbildung bereits während der Biosynthese der Proteine (co-translational) stattfinden kann und nicht stets erst danach (post-translational) erfolgt. Da Fehlassemblierungen von Proteinen zu Funktionsverlusten und adversen Effekten führen, ist eine präzise und verlässliche Proteinkomplexbildung sowohl für zelluläre Prozesse als auch für biotechnologische Anwendungen essenziell. Mit experimentellen Methoden lassen sich zwar u.a. die Stöchiometrie und die Struktur von Proteinkomplexen bestimmen, jedoch bisher nicht die Dynamik der Komplexbildung auf unterschiedlichen Zeitskalen. Daher sind grundlegende Mechanismen der Proteinkomplexbildung noch nicht vollständig verstanden. Die hier vorgestellte, auf experimentellen Erkenntnissen aufbauende, computergestützte Modellierung der Proteinkomplexbildung erlaubt eine umfassende Analyse des Einflusses physikalisch-chemischer Parameter auf den Assemblierungsprozess. Die Modelle bilden möglichst realistisch die experimentellen Systeme der Kooperationspartner (Bar-Ziv, Weizmann-Institut, Israel; Bukau und Kramer, Universität Heidelberg) ab, um damit die Assemblierung von Proteinkomplexen einerseits in einem quasi-zweidimensionalen synthetischen Expressionssystem (in vitro) und andererseits im Bakterium Escherichia coli (in vivo) untersuchen zu können. Mit Hilfe eines vereinfachten Expressionssystems, in dem die Proteine nur an die Chip-Oberfläche, aber nicht aneinander binden können, wird das theoretische Modell parametrisiert. In diesem vereinfachten in-vitro-System durchläuft die Effizienz der Komplexbildung drei Regime – ein bindedominiertes Regime, ein Mischregime und ein produktionsdominiertes Regime. Ihr Maximum erreicht die Effizienz dabei kurz nach dem Übergang vom bindedominierten ins Mischregime und fällt anschließend monoton ab. Sowohl im nicht-vereinfachten in-vitro- als auch im in-vivo-System koexistieren je zwei konkurrierende Assemblierungspfade: Im in-vitro-System erfolgt die Komplexbildung entweder spontan in wässriger Lösung (Lösungsassemblierung) oder aber in einer definierten Schrittfolge an der Chip-Oberfläche (Oberflächenassemblierung); Im in-vivo-System konkurrieren hingegen die co- und die post-translationale Komplexbildung. Es zeigt sich, dass die Dominanz der Assemblierungspfade im in-vitro-System zeitabhängig ist und u.a. durch die Limitierung und Stärke der Bindestellen auf der Chip-Oberfläche beeinflusst werden kann. Im in-vivo-System hat der räumliche Abstand zwischen den Syntheseorten der beiden Proteinkomponenten nur dann einen Einfluss auf die Komplexbildung, wenn die Untereinheiten schnell degradieren. In diesem Fall dominiert die co-translationale Assemblierung auch auf kurzen Zeitskalen deutlich, wohingegen es bei stabilen Untereinheiten zu einem Wechsel von der Dominanz der post- hin zu einer geringen Dominanz der co-translationalen Assemblierung kommt. Mit den in-silico-Modellen lässt sich neben der Dynamik u.a. auch die Lokalisierung der Komplexbildung und -bindung darstellen, was einen Vergleich der theoretischen Vorhersagen mit experimentellen Daten und somit eine Validierung der Modelle ermöglicht. Der hier präsentierte in-silico Ansatz ergänzt die experimentellen Methoden, und erlaubt so, deren Ergebnisse zu interpretieren und neue Erkenntnisse davon abzuleiten. KW - Assemblierung KW - Proteine KW - Multiproteinkomplexbildung KW - co-translationale Assemblierung KW - post-translationale Assemblierung KW - Lösung KW - Oberfläche KW - Lösungsassemblierung KW - Oberflächenassemblierung KW - co-translational KW - post-translational KW - assembly KW - proteins KW - multi protein complex formation Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-550742 ER - TY - JOUR A1 - Geier, Stephan A1 - Dorsch, Matti A1 - Pelisoli, Ingrid A1 - Reindl, Nicole A1 - Heber, Ulrich A1 - Irrgang, Andreas T1 - Radial velocity variability and the evolution of hot subdwarf stars JF - Astronomy and astrophysics : an international weekly journal N2 - Hot subdwarf stars represent a late and peculiar stage in the evolution of low-mass stars, since they are likely formed by close binary interactions. In this work, we perform a radial velocity (RV) variability study of a sample of 646 hot subdwarfs with multi-epoch radial velocities based on spectra from Sloan Digital Sky Survey (SDSS) and Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST). The atmospheric parameters and RVs were taken from the literature. For stars with archival spectra but without literature values, we determined the parameters by fitting model atmospheres. In addition, we redetermined the atmospheric parameters and RVs for all the He-enriched sdO/Bs. This broad sample allowed us to study RV-variability as a function of the location in the T-eff - log g- and T-eff - log n(He)/n(H) diagrams in a statistically significant way. We used the fraction of RV-variable stars and the distribution of the maximum RV variations Delta RVmax as diagnostics. Both indicators turned out to be quite inhomogeneous across the studied parameter ranges. A striking feature is the completely dissimilar behaviour of He-poor and He-rich hot subdwarfs. While the former have a high fraction of close binaries, almost no significant RV variations could be detected for the latter. This has led us to the conclusion that there is likely no evolutionary connection between these subtypes. On the other hand, intermediate He-rich- and extreme He-rich sdOB/Os are more likely to be related. Furthermore, we conclude that the vast majority of this population is formed via one or several binary merger channels. Hot subdwarfs with temperatures cooler than similar to 24 000 K tend to show fewer and smaller RV-variations. These objects might constitute a new subpopulation of binaries with longer periods and late-type or compact companions. The RV-variability properties of the extreme horizontal branch (EHB) and corresponding post-EHB populations of the He-poor hot subdwarfs match and confirm the predicted evolutionary connection between them. Stars found below the canonical EHB at somewhat higher surface gravities show large RV variations and a high RV variability fraction. These properties are consistent with most of them being low-mass EHB stars or progenitors of low-mass helium white dwarfs in close binaries. KW - subdwarfs KW - binaries: spectroscopic KW - stars: horizontal-branch Y1 - 2022 U6 - https://doi.org/10.1051/0004-6361/202143022 SN - 0004-6361 SN - 1432-0746 VL - 661 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Geist, Emily A1 - Gallagher, John S. A1 - Kotulla, Ralf A1 - Oskinova, Lida A1 - Hamann, Wolf-Rainer A1 - Ramachandran, Varsha A1 - Sabbi, Elena A1 - Smith, Linda J. A1 - Kniazev, Alexey A1 - Nota, Antonella A1 - Rickard, Matthew J. T1 - Ionization and star formation in the giant H ii region SMC-N66 JF - Publications of the Astronomical Society of the Pacific N2 - The NGC 346 young stellar system and associated N66 giant H ii region in the Small Magellanic Cloud are the nearest example of a massive star-forming event in a low metallicity (Z approximate to 0.2Z (circle dot)) galaxy. With an age of less than or similar to 3 Myr this system provides a unique opportunity to study relationships between massive stars and their associated H ii region. Using archival data, we derive a total H alpha luminosity of L(H alpha) = 4.1 x 10(38) erg s(-1) corresponding to an H-photoionization rate of 3 x 10(50) s(-1). A comparison with a predicted stellar ionization rate derived from the more than 50 known O-stars in NGC 346, including massive stars recently classified from Hubble Space Telescope far-ultraviolet (FUV) spectra, indicates an approximate ionization balance. Spectra obtained with SALT suggest the ionization structure of N66 could be consistent with some leakage of ionizing photons. Due to the low metallicity, the FUV luminosity from NGC 346 is not confined to the interstellar cloud associated with N66. Ionization extends through much of the spatial extent of the N66 cloud complex, and most of the cloud mass is not ionized. The stellar mass estimated from nebular L(H alpha) appears to be lower than masses derived from the census of resolved stars which may indicate a disconnect between the formation of high and low mass stars in this region. We briefly discuss implications of the properties of N66 for studies of star formation and stellar feedback in low metallicity environments. Y1 - 2022 U6 - https://doi.org/10.1088/1538-3873/ac697b SN - 0004-6280 SN - 1538-3873 VL - 134 IS - 1036 PB - IOP Publishing CY - Bristol ER - TY - JOUR A1 - Gengel, Erik A1 - Pikovskij, Arkadij T1 - Phase reconstruction from oscillatory data with iterated Hilbert transform embeddings BT - benefits and limitations JF - Physica : D, Nonlinear phenomena N2 - In the data analysis of oscillatory systems, methods based on phase reconstruction are widely used to characterize phase-locking properties and inferring the phase dynamics. The main component in these studies is an extraction of the phase from a time series of an oscillating scalar observable. We discuss a practical procedure of phase reconstruction by virtue of a recently proposed method termed iterated Hilbert transform embeddings. We exemplify the potential benefits and limitations of the approach by applying it to a generic observable of a forced Stuart-Landau oscillator. Although in many cases, unavoidable amplitude modulation of the observed signal does not allow for perfect phase reconstruction, in cases of strong stability of oscillations and a high frequency of the forcing, iterated Hilbert transform embeddings significantly improve the quality of the reconstructed phase. We also demonstrate that for significant amplitude modulation, iterated embeddings do not provide any improvement. KW - Data analysis KW - Phase reconstruction KW - Hilbert transform Y1 - 2021 U6 - https://doi.org/10.1016/j.physd.2021.133070 SN - 0167-2789 SN - 1872-8022 VL - 429 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Gerhard, Reimund A1 - Kacprzyk, Ryszard T1 - Paul Böning - early electret researcher in Shanghai and Wroclaw (1922-1945) JF - IEEE transactions on dielectrics and electrical insulation N2 - The scientific career and the research activities of Paul Boening, especially during his tenures at Tongji University in Shanghai (Woosung Campus, 1922-1936) and the Technical University of Wroclaw (TH Breslau, 1936-1945), are briefly reviewed. In particular, Boening's pioneering investigations in the area of electrets and space charge in dielectrics are emphasized. We attempt to shed some light on the significant achievements of a virtually unknown contributor to the early history of electrets and of space-charge research and high-voltage engineering, during the 1920s and 1930s. It should be noted that dielectrics research was a truly international endeavor already at that time. KW - dielectrics KW - electrets KW - electrostatic KW - experiments KW - (high-)voltage measurements KW - space charge Y1 - 2022 U6 - https://doi.org/10.1109/TDEI.2022.3168372 SN - 1070-9878 SN - 1558-4135 VL - 29 IS - 3 SP - 853 EP - 858 PB - Institute of Electrical and Electronics Engineers CY - New York, NY ER - TY - JOUR A1 - Gerlach, Marius A1 - Preitschopf, Tobias A1 - Karaev, Emil A1 - Quitian-Lara, Heidy Mayerly A1 - Mayer, Dennis A1 - Bozek, John A1 - Fischer, Ingo A1 - Fink, Reinhold F. T1 - Auger electron spectroscopy of fulminic acid, HCNO BT - an experimental and theoretical study JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - HCNO is a molecule of considerable astrochemical interest as a precursor to prebiotic molecules. It is synthesized by preparative pyrolysis and is unstable at room temperature. Here, we investigate its spectroscopy in the soft X-ray regime at the C 1s, N 1s and O 1s edges. All 1s ionization energies are reported and X-ray absorption spectra reveal the transitions from the 1s to the pi* state. Resonant and normal Auger electron spectra for the decay of the core hole states are recorded in a hemispherical analyzer. An assignment of the experimental spectra is provided with the aid of theoretical counterparts. The latter are using a valence configuration interaction representation of the intermediate and final state energies and wavefunctions, the one-center approximation for transition rates and band shapes according to the moment theory. The computed spectra are in very good agreement with the experimental data and most of the relevant bands are assigned. Additionally, we present a simple approach to estimate relative Auger transition rates on the basis of a minimal basis representation of the molecular orbitals. We demonstrate that this provides a qualitatively good and reliable estimate for several signals in the normal and resonant Auger electron spectra which have significantly different intensities in the decay of the three core holes. Y1 - 2022 U6 - https://doi.org/10.1039/d2cp02104h SN - 1463-9076 SN - 1463-9084 VL - 24 IS - 25 SP - 15217 EP - 15229 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Gieg, Henrique A1 - Schianchi, Federico A1 - Dietrich, Tim A1 - Ujevic, Maximiliano T1 - Incorporating a Radiative Hydrodynamics Scheme in the Numerical-Relativity Code BAM JF - Universe : open access journal N2 - To study binary neutron star systems and to interpret observational data such as gravitational-wave and kilonova signals, one needs an accurate description of the processes that take place during the final stages of the coalescence, for example, through numerical-relativity simulations. In this work, we present an updated version of the numerical-relativity code BAM in order to incorporate nuclear-theory-based equations of state and a simple description of neutrino interactions through a neutrino leakage scheme. Different test simulations, for stars undergoing a neutrino-induced gravitational collapse and for binary neutron stars systems, validate our new implementation. For the binary neutron stars systems, we show that we can evolve stably and accurately distinct microphysical models employing the different equations of state: SFHo, DD2, and the hyperonic BHB Lambda phi. Overall, our test simulations have good agreement with those reported in the literature. KW - numerical relativity KW - binary neutron stars KW - neutrinos KW - leakage scheme Y1 - 2022 U6 - https://doi.org/10.3390/universe8070370 SN - 2218-1997 VL - 8 IS - 7 PB - MDPI CY - Basel ER - TY - JOUR A1 - Grebenkov, Denis S. T1 - An encounter-based approach for restricted diffusion with a gradient drift JF - Journal of physics : A, Mathematical and theoretical N2 - We develop an encounter-based approach for describing restricted diffusion with a gradient drift toward a partially reactive boundary. For this purpose, we introduce an extension of the Dirichlet-to-Neumann operator and use its eigenbasis to derive a spectral decomposition for the full propagator, i.e. the joint probability density function for the particle position and its boundary local time. This is the central quantity that determines various characteristics of diffusion-influenced reactions such as conventional propagators, survival probability, first-passage time distribution, boundary local time distribution, and reaction rate. As an illustration, we investigate the impact of a constant drift onto the boundary local time for restricted diffusion on an interval. More generally, this approach accesses how external forces may influence the statistics of encounters of a diffusing particle with the reactive boundary. KW - boundary local time KW - reflected Brownian motion KW - diffusion-influenced KW - reactions KW - surface reactivity KW - Robin boundary condition KW - Heterogeneous KW - catalysis Y1 - 2022 U6 - https://doi.org/10.1088/1751-8121/ac411a SN - 1751-8113 SN - 1751-8121 VL - 55 IS - 4 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Grebenkov, Denis S. A1 - Kumar, Aanjaneya T1 - First-passage times of multiple diffusing particles with reversible target-binding kinetics JF - Journal of physics : A, Mathematical and theoretical N2 - We investigate a class of diffusion-controlled reactions that are initiated at the time instance when a prescribed number K among N particles independently diffusing in a solvent are simultaneously bound to a target region. In the irreversible target-binding setting, the particles that bind to the target stay there forever, and the reaction time is the Kth fastest first-passage time to the target, whose distribution is well-known. In turn, reversible binding, which is common for most applications, renders theoretical analysis much more challenging and drastically changes the distribution of reaction times. We develop a renewal-based approach to derive an approximate solution for the probability density of the reaction time. This approximation turns out to be remarkably accurate for a broad range of parameters. We also analyze the dependence of the mean reaction time or, equivalently, the inverse reaction rate, on the main parameters such as K, N, and binding/unbinding constants. Some biophysical applications and further perspectives are briefly discussed. KW - first-passage time KW - diffusion-controlled reactions KW - reversible binding KW - extreme statistics Y1 - 2022 U6 - https://doi.org/10.1088/1751-8121/ac7e91 SN - 1751-8113 SN - 1751-8121 VL - 55 IS - 32 PB - IOP Publ. CY - Bristol ER - TY - JOUR A1 - Grebenkov, Denis S. A1 - Metzler, Ralf A1 - Oshanin, Gleb T1 - Search efficiency in the Adam-Delbruck reduction-of-dimensionality scenario versus direct diffusive search JF - New journal of physics : the open-access journal for physics N2 - The time instant-the first-passage time (FPT)-when a diffusive particle (e.g., a ligand such as oxygen or a signalling protein) for the first time reaches an immobile target located on the surface of a bounded three-dimensional domain (e.g., a hemoglobin molecule or the cellular nucleus) is a decisive characteristic time-scale in diverse biophysical and biochemical processes, as well as in intermediate stages of various inter- and intra-cellular signal transduction pathways. Adam and Delbruck put forth the reduction-of-dimensionality concept, according to which a ligand first binds non-specifically to any point of the surface on which the target is placed and then diffuses along this surface until it locates the target. In this work, we analyse the efficiency of such a scenario and confront it with the efficiency of a direct search process, in which the target is approached directly from the bulk and not aided by surface diffusion. We consider two situations: (i) a single ligand is launched from a fixed or a random position and searches for the target, and (ii) the case of 'amplified' signals when N ligands start either from the same point or from random positions, and the search terminates when the fastest of them arrives to the target. For such settings, we go beyond the conventional analyses, which compare only the mean values of the corresponding FPTs. Instead, we calculate the full probability density function of FPTs for both scenarios and study its integral characteristic-the 'survival' probability of a target up to time t. On this basis, we examine how the efficiencies of both scenarios are controlled by a variety of parameters and single out realistic conditions in which the reduction-of-dimensionality scenario outperforms the direct search. KW - first-passage times KW - Adam-Delbruck scenario KW - dimensional reduction KW - bulk KW - and surface diffusion Y1 - 2022 U6 - https://doi.org/10.1088/1367-2630/ac8824 SN - 1367-2630 VL - 24 IS - 8 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Griggio, Massimo A1 - Bedin, Luigi R. A1 - Raddi, Roberto A1 - Reindl, Nicole A1 - Tomasella, Lina A1 - Scalco, M. A1 - Salaris, M. A1 - Cassisi, S. A1 - Ochner, P. A1 - Ciroi, S. A1 - Rosati, P. A1 - Nardiello, Domenico A1 - Anderson, J. A1 - Libralato, Mattia A1 - Bellini, A. A1 - Vallenari, A. A1 - Spina, L. A1 - Pedani, M. T1 - Astro-photometric study of M37 with Gaia and wide-field ugi-imaging JF - Monthly notices of the Royal Astronomical Society N2 - We present an astrometric and photometric wide-field study of the Galactic open star cluster M37 (NGC 2099). The studied field was observed with ground-based images covering a region of about four square degrees in the Sloan-like filters ugi. We exploited the Gaia catalogue to calibrate the geometric distortion of the large field mosaics, developing software routines that can be also applied to other wide-field instruments. The data are used to identify the hottest white dwarf (WD) member candidates of M37. Thanks to the Gaia EDR3 exquisite astrometry we identified seven such WD candidates, one of which, besides being a high-probability astrometric member, is the putative central star of a planetary nebula. To our knowledge, this is a unique object in an open cluster, and we have obtained follow-up low-resolution spectra that are used for a qualitative characterization of this young WD. Finally, we publicly release a three-colour atlas and a catalogue of the sources in the field of view, which represents a complement of existing material. KW - catalogues KW - white dwarfs KW - open clusters and associations: individual: KW - M37 (NGC2099) Y1 - 2022 U6 - https://doi.org/10.1093/mnras/stac1920 SN - 0035-8711 SN - 1365-2966 VL - 515 IS - 2 SP - 1841 EP - 1853 PB - Oxford University Press CY - Oxford ER - TY - JOUR A1 - Grischek, Max A1 - Caprioglio, Pietro A1 - Zhang, Jiahuan A1 - Pena-Camargo, Francisco A1 - Sveinbjornsson, Kari A1 - Zu, Fengshuo A1 - Menzel, Dorothee A1 - Warby, Jonathan A1 - Li, Jinzhao A1 - Koch, Norbert A1 - Unger, Eva A1 - Korte, Lars A1 - Neher, Dieter A1 - Stolterfoht, Martin A1 - Albrecht, Steve T1 - Efficiency Potential and Voltage Loss of Inorganic CsPbI2Br Perovskite Solar Cells JF - Solar RRL N2 - Inorganic perovskite solar cells show excellent thermal stability, but the reported power conversion efficiencies are still lower than for organic-inorganic perovskites. This is mainly caused by lower open-circuit voltages (V(OC)s). Herein, the reasons for the low V-OC in inorganic CsPbI2Br perovskite solar cells are investigated. Intensity-dependent photoluminescence measurements for different layer stacks reveal that n-i-p and p-i-n CsPbI2Br solar cells exhibit a strong mismatch between quasi-Fermi level splitting (QFLS) and V-OC. Specifically, the CsPbI2Br p-i-n perovskite solar cell has a QFLS-e center dot V-OC mismatch of 179 meV, compared with 11 meV for a reference cell with an organic-inorganic perovskite of similar bandgap. On the other hand, this study shows that the CsPbI2Br films with a bandgap of 1.9 eV have a very low defect density, resulting in an efficiency potential of 20.3% with a MeO-2PACz hole-transporting layer and 20.8% on compact TiO2. Using ultraviolet photoelectron spectroscopy measurements, energy level misalignment is identified as a possible reason for the QFLS-e center dot V-OC mismatch and strategies for overcoming this V-OC limitation are discussed. This work highlights the need to control the interfacial energetics in inorganic perovskite solar cells, but also gives promise for high efficiencies once this issue is resolved. KW - CsPbI2Br KW - efficiency potentials KW - inorganic perovskites KW - photoluminescence KW - solar cells KW - voltage losses Y1 - 2022 U6 - https://doi.org/10.1002/solr.202200690 SN - 2367-198X VL - 6 IS - 11 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Guggenberger, Tobias A1 - Chechkin, Aleksei A1 - Metzler, Ralf T1 - Absence of stationary states and non-Boltzmann distributions of fractional Brownian motion in shallow external potentials JF - New journal of physics : the open-access journal for physics N2 - We study the diffusive motion of a particle in a subharmonic potential of the form U(x) = |x|( c ) (0 < c < 2) driven by long-range correlated, stationary fractional Gaussian noise xi ( alpha )(t) with 0 < alpha <= 2. In the absence of the potential the particle exhibits free fractional Brownian motion with anomalous diffusion exponent alpha. While for an harmonic external potential the dynamics converges to a Gaussian stationary state, from extensive numerical analysis we here demonstrate that stationary states for shallower than harmonic potentials exist only as long as the relation c > 2(1 - 1/alpha) holds. We analyse the motion in terms of the mean squared displacement and (when it exists) the stationary probability density function. Moreover we discuss analogies of non-stationarity of Levy flights in shallow external potentials. KW - diffusion KW - Boltzmann distribution KW - fractional Brownian motion Y1 - 2022 U6 - https://doi.org/10.1088/1367-2630/ac7b3c SN - 1367-2630 VL - 24 IS - 7 PB - Dt. Physikalische Ges. CY - [Bad Honnef] ER - TY - JOUR A1 - Guo, Yingjie A1 - Ni, Binbin A1 - Fu, Song A1 - Wang, Dedong A1 - Shprits, Yuri Y. A1 - Zhelavskaya, Irina A1 - Feng, Minghang A1 - Guo, Deyu T1 - Identification of controlling geomagnetic and solar wind factors for magnetospheric chorus intensity using feature selection techniques JF - Journal of geophysical research : A, Space physics N2 - Using over-5-year EMFISIS wave measurements from Van Allen Probes, we present a detailed survey to identify the controlling factors among the geomagnetic indices and solar wind parameters for the 1-min root mean square amplitudes of lower band chorus (LBC) and upper band chorus (UBC). A set of important features are automatically determined by feature selection techniques, namely, Random Forest and Maximum Relevancy Minimum Redundancy. Our analysis results indicate the AE index with zero-time-delay dominates the intensity evolution of LBC and UBC, consistent with the evidence that chorus waves prefer to occur and amplify during enhanced substorm periods. Regarding solar wind parameters, solar wind speed and IMF B-z are identified as the controlling factors for chorus wave intensity. Using the combination of all these important features, a predictive neural network model of chorus wave intensity is established to reconstruct the temporal variations of chorus wave intensity, for which application of Random Forest produces the overall best performance. Plain Language Summary Whistler mode chorus waves are electromagnetic waves observed in the low-density region near the geomagnetic equator outside the plasmapause. The dynamics of Earth's radiation belts are largely influenced by chorus waves owing to their dual contributions to both radiation belt electron acceleration and loss. In this study, we use feature selection techniques to identify the controlling geomagnetic and solar wind factors for magnetospheric chorus waves. Feature selection techniques implement the processes which can select the features most influential to the output. In this study, the inputs are geomagnetic indices and solar wind parameters and the output is the chorus wave intensity. The results indicate that AE index with zerotime delay dominates the chorus wave intensity. Furthermore, solar wind speed and IMF B-z are identified as the most important solar wind drivers for chorus wave intensity. On basis of the combination of all these important geomagnetic and solar wind controlling factors, we develop a neural network model of chorus wave intensity, and find that the model with the inputs identified using the Random Forest method produces the overall best performance. Y1 - 2021 U6 - https://doi.org/10.1029/2021JA029926 SN - 2169-9380 SN - 2169-9402 VL - 127 IS - 1 PB - Wiley CY - Hoboken, NJ ER -