TY  - JOUR
A1  - Mayer, Dennis
A1  - Picconi, David
A1  - Robinson, Matthew S.
A1  - Gühr, Markus
T1  - Experimental and theoretical gas-phase absorption spectra of thionated uracils
JF  - Chemical physics : a journal devoted to experimental and theoretical research involving problems of both a chemical and physical nature
N2  - We present a comparative study of the gas-phase UV spectra of uracil and its thionated counterparts (2-thiouracil, 4-thiouracil and 2,4-dithiouracil), closely supported by time-dependent density functional theory calculations to assign the transitions observed. We systematically discuss pure gas-phase spectra for the (thio)uracils in the range of 200-400 nm (similar to 3.2-6.4 eV), and examine the spectra of all four species with a single theoretical approach. We note that specific vibrational modelling is needed to accurately determine the spectra across the examined wavelength range, and systematically model the transitions that appear at wavelengths shorter than 250 nm. Additionally, we find in the cases of 2-thiouracil and 2,4-dithiouracil, that the gas-phase spectra deviate significantly from some previously published solution-phase spectra, especially those collected in basic environments.
KW  - Thiouracil
KW  - Uracil
KW  - UV-VIS Spectroscopy
KW  - Excited-state calculations;
KW  - TD-DFT
KW  - Gas phase
Y1  - 2022
U6  - https://doi.org/10.1016/j.chemphys.2022.111500
SN  - 0301-0104
VL  - 558
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Serrano-Munoz, Itziar
A1  - Fernández Serrano, Ricardo
A1  - Saliwan-Neumann, Romeo
A1  - Gonzalez-Doncel, Gaspar
A1  - Bruno, Giovanni
T1  - Dislocation substructures in pure aluminium after creep deformation as studied by electron backscatter diffraction
JF  - Journal of applied crystallography / International Union of Crystallography
N2  - In the present work, electron backscatter diffraction was used to determine the microscopic dislocation structures generated during creep (with tests interrupted at the steady state) in pure 99.8% aluminium. This material was investigated at two different stress levels, corresponding to the power-law and power-law breakdown regimes. The results show that the formation of subgrain cellular structures occurs independently of the crystallographic orientation. However, the density of these cellular structures strongly depends on the grain crystallographic orientation with respect to the tensile axis direction, with (111) grains exhibiting the highest densities at both stress levels. It is proposed that this behaviour is due to the influence of intergranular stresses, which is different in (111) and (001) grains.
KW  - creep
KW  - pure aluminium
KW  - electron backscatter diffraction (EBSD)
KW  - cellular
KW  - structures
KW  - power law and power-law breakdown
Y1  - 2022
U6  - https://doi.org/10.1107/S1600576722005209
SN  - 1600-5767
VL  - 55
SP  - 860
EP  - 869
PB  - Munksgaard
CY  - Copenhagen
ER  - 
TY  - JOUR
A1  - Gupta, Banshi D.
A1  - Pathak, Anisha
A1  - Shrivastav, Anand
T1  - Optical Biomedical Diagnostics Using Lab-on-Fiber Technology
BT  - a review
JF  - Photonics : open access journal
N2  - Point-of-care and in-vivo bio-diagnostic tools are the current need for the present critical scenarios in the healthcare industry. The past few decades have seen a surge in research activities related to solving the challenges associated with precise on-site bio-sensing. Cutting-edge fiber optic technology enables the interaction of light with functionalized fiber surfaces at remote locations to develop a novel, miniaturized and cost-effective lab on fiber technology for bio-sensing applications. The recent remarkable developments in the field of nanotechnology provide innumerable functionalization methodologies to develop selective bio-recognition elements for label free biosensors. These exceptional methods may be easily integrated with fiber surfaces to provide highly selective light-matter interaction depending on various transduction mechanisms. In the present review, an overview of optical fiber-based biosensors has been provided with focus on physical principles used, along with the functionalization protocols for the detection of various biological analytes to diagnose the disease. The design and performance of these biosensors in terms of operating range, selectivity, response time and limit of detection have been discussed. In the concluding remarks, the challenges associated with these biosensors and the improvement required to develop handheld devices to enable direct target detection have been highlighted.
KW  - fiber optic sensors
KW  - synthesis
KW  - interferometry
KW  - fluorescence
KW  - SERS
KW  - SPR
KW  - immunosensors
KW  - enzymatic sensors
KW  - molecular imprinted polymers
Y1  - 2022
U6  - https://doi.org/10.3390/photonics9020086
SN  - 2304-6732
VL  - 9
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Kotz, Maximilian
A1  - Levermann, Anders
A1  - Wenz, Leonie
T1  - The effect of rainfall changes on economic production
JF  - Nature : the international journal of science
N2  - Macro-economic assessments of climate impacts lack an analysis of the distribution of daily rainfall, which can resolve both complex societal impact channels and anthropogenically forced changes(1-6). Here, using a global panel of subnational economic output for 1,554 regions worldwide over the past 40 years, we show that economic growth rates are reduced by increases in the number of wet days and in extreme daily rainfall, in addition to responding nonlinearly to the total annual and to the standardized monthly deviations of rainfall. Furthermore, high-income nations and the services and manufacturing sectors are most strongly hindered by both measures of daily rainfall, complementing previous work that emphasized the beneficial effects of additional total annual rainfall in low-income, agriculturally dependent economies(4,7). By assessing the distribution of rainfall at multiple timescales and the effects on different sectors, we uncover channels through which climatic conditions can affect the economy. These results suggest that anthropogenic intensification of daily rainfall extremes(8-10) will have negative global economic consequences that require further assessment by those who wish to evaluate the costs of anthropogenic climate change.
Y1  - 2022
U6  - https://doi.org/10.1038/s41586-021-04283-8
SN  - 0028-0836
SN  - 1476-4687
VL  - 601
IS  - 7892
SP  - 223
EP  - 227
PB  - Macmillan Publishers Limited, part of Springer Nature
CY  - London
ER  - 
TY  - JOUR
A1  - Steigert, Alexander
A1  - Kojda, Sandrino Danny
A1  - Ibaceta-Jaña, Josefa Fernanda
A1  - Abou-Ras, Daniel
A1  - Gunder, René
A1  - Alktash, Nivin
A1  - Habicht, Klaus
A1  - Wagner, Markus Raphael
A1  - Klenk, Reiner
A1  - Raoux, Simone
A1  - Szyszka, Bernd
A1  - Lauermann, Iver
A1  - Muydinov, Ruslan
T1  - Water-assisted crystallization of amorphous indium zinc oxide films
JF  - Materials today. Communications
N2  - Transparent conductive materials based on indium oxide remain yet irreplaceable in various optoelectronic applications. Amorphous oxides appear especially attractive for technology as they are isotropic, demonstrate relatively high electron mobility and can be processed at low temperatures. Among them is indium zinc oxide (IZO) with a large zinc content that is crucial for keeping the amorphous state but redundant for the doping. In this work we investigated water-free and water containing IZO films obtained by radio frequency sputtering. The correlation between temperature driven changes of the chemical state, the optical and electrical properties as well as the progression of crystallization was in focus. Such characterization methods as: scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, temperature dependent Hall-effect measurements and others were applied. Temperature dependent electrical properties of amorphous IZO and IZO:H2O films were found to evolve similarly. Based on our experience in In2O3:H2O (In2O3:H or IOH) we proposed an explanation for the changes observed. Water admixture was found to decrease crystallization temperature of IZO significantly from similar to 550 degrees C to similar to 280 degrees C. Herewith, the presence and concentration of water and/or hydroxyls was found to determine Zn distribution in the film. In particular, Zn enrichment was detected at the film's surface respective to the high water and/or hydroxyl amount. Raman spectra revealed a two-dimensional crystallization of w-ZnO which precedes regardless water presence an extensive In2O3 crystallization. An abrupt loss of electron mobility as a result of crystallization was attributed to the formation of ZnO interlayer on grain boundaries.
KW  - IZO
KW  - Thin films
KW  - TCOs
KW  - Crystallization
KW  - Water-assisted crystallization
Y1  - 2022
U6  - https://doi.org/10.1016/j.mtcomm.2022.103213
SN  - 2352-4928
VL  - 31
PB  - Elsevier
CY  - Amsterdam
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  - Mani, Deepak
A1  - Kupsch, Andreas
A1  - Müller, Bernd R.
A1  - Bruno, Giovanni
T1  - Diffraction Enhanced Imaging Analysis with Pseudo-Voigt Fit Function
JF  - Journal of imaging : open access journal
N2  - Diffraction enhanced imaging (DEI) is an advanced digital radiographic imaging technique employing the refraction of X-rays to contrast internal interfaces. This study aims to qualitatively and quantitatively evaluate images acquired using this technique and to assess how different fitting functions to the typical rocking curves (RCs) influence the quality of the images. RCs are obtained for every image pixel. This allows the separate determination of the absorption and the refraction properties of the material in a position-sensitive manner. Comparison of various types of fitting functions reveals that the Pseudo-Voigt (PsdV) function is best suited to fit typical RCs. A robust algorithm was developed in the Python programming language, which reliably extracts the physically meaningful information from each pixel of the image. We demonstrate the potential of the algorithm with two specimens: a silicone gel specimen that has well-defined interfaces, and an additively manufactured polycarbonate specimen.
KW  - diffraction enhanced imaging
KW  - analyzer-based imaging
KW  - X-ray refraction;
KW  - non-destructive evaluation
KW  - Pseudo-Voigt fit function
KW  - Python
Y1  - 2022
U6  - https://doi.org/10.3390/jimaging8080206
SN  - 2313-433X
VL  - 8
IS  - 8
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Meyer, Dominique M.-A.
A1  - Velazquez, Pablo F.
A1  - Petruk, Oleh
A1  - Chiotellis, Alexandros
A1  - Pohl, Martin
A1  - Camps-Farina, Artemi
A1  - Petrov, Miroslav
A1  - Reynoso, Estela M.
A1  - Toledo-Roy, Juan C.
A1  - Schneiter, E. Matias
A1  - Castellanos-Ramirez, Antonio
A1  - Esquivel, Alejandro
T1  - Rectangular core-collapse supernova remnants
BT  - application to Puppis A
JF  - Monthly notices of the Royal Astronomical Society
N2  - Core-collapse supernova remnants are the gaseous nebulae of galactic interstellar media (ISM) formed after the explosive death of massive stars. Their morphology and emission properties depend both on the surrounding circumstellar structure shaped by the stellar wind-ISM interaction of the progenitor star and on the local conditions of the ambient medium. In the warm phase of the Galactic plane (n approximate to 1 cm(-3), T approximate to 8000 K), an organized magnetic field of strength 7 mu G has profound consequences on the morphology of the wind bubble of massive stars at rest. In this paper, we show through 2.5D magnetohydrodynamical simulations, in the context of a Wolf-Rayet-evolving 35 M 0 star, that it affects the development of its supernova remnant. When the supernova remnant reaches its middle age (15-20 kyr), it adopts a tubular shape that results from the interaction between the isotropic supernova ejecta and the anisotropic, magnetized, shocked stellar progenitor bubble into which the supernova blast wave expands. Our calculations for non-thermal emission, i.e. radio synchrotron and inverse-Compton radiation, reveal that such supernova remnants can, due to projection effects, appear as rectangular objects in certain cases. This mechanism for shaping a supernova remnant is similar to the bipolar and elliptical planetary nebula production by wind-wind interaction in the low-mass regime of stellar evolution. If such a rectangular core-collapse supernova remnant is created, the progenitor star must not have been a runaway star. We propose that such a mechanism is at work in the shaping of the asymmetric core-collapse supernova remnant Puppis A.
KW  - stars: evolution
KW  - stars: massive
KW  - ISM: supernova remnants
KW  - methods: MHD
Y1  - 2022
U6  - https://doi.org/10.1093/mnras/stac1832
SN  - 0035-8711
SN  - 1365-2966
VL  - 515
IS  - 1
SP  - 594
EP  - 605
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Hornemann, Andrea
A1  - Eichert, Diane Madeleine
A1  - Hoehl, Arne
A1  - Tiersch, Brigitte
A1  - Ulm, Gerhard
A1  - Ryadnov, Maxim G.
A1  - Beckhoff, Burkhard
T1  - Investigating Membrane-Mediated Antimicrobial Peptide Interactions with Synchrotron Radiation Far-Infrared Spectroscopy
JF  - ChemPhysChem : a European journal of chemical physics and physical chemistry
N2  - Synchrotron radiation-based Fourier transform infrared spectroscopy enables access to vibrational information from mid over far infrared to even terahertz domains. This information may prove critical for the elucidation of fundamental bio-molecular phenomena including folding-mediated innate host defence mechanisms. Antimicrobial peptides (AMPs) represent one of such phenomena. These are major effector molecules of the innate immune system, which favour attack on microbial membranes. AMPs recognise and bind to the membranes whereupon they assemble into pores or channels destabilising the membranes leading to cell death. However, specific molecular interactions responsible for antimicrobial activities have yet to be fully understood. Herein we probe such interactions by assessing molecular specific variations in the near-THz 400-40 cm(-1) range for defined helical AMP templates in reconstituted phospholipid membranes. In particular, we show that a temperature-dependent spectroscopic analysis, supported by 2D correlative tools, provides direct evidence for the membrane-induced and folding-mediated activity of AMPs. The far-FTIR study offers a direct and information-rich probe of membrane-related antimicrobial interactions.
KW  - antimicrobial peptides
KW  - electrostatic interactions
KW  - IR spectroscopy
KW  - phospholipid membranes
KW  - protein folding
Y1  - 2022
U6  - https://doi.org/10.1002/cphc.202100815
SN  - 1439-4235
SN  - 1439-7641
VL  - 23
IS  - 4
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Toalá, Jesús Alberto
A1  - Bowman, Dominic
A1  - Van Reeth, Timothy
A1  - Todt, Helge Tobias
A1  - Dsilva, Karan
A1  - Shenar, Tomer
A1  - Koenigsberger, Gloria Suzanne
A1  - Estrada-Dorado, Sandino
A1  - Oskinova, Lida
A1  - Hamann, Wolf-Rainer
T1  - Multiple variability time-scales of the early nitrogen-rich Wolf-Rayet star WR 7
JF  - Monthly notices of the Royal Astronomical Society
N2  - We present the analysis of the optical variability of the early, nitrogen-rich Wolf-Rayet (WR) star WR 7. The analysis of multisector Transiting Exoplanet Survey Satellite (TESS) light curves and high-resolution spectroscopic observations confirm multiperiodic variability that is modulated on time-scales of years. We detect a dominant period of 2.6433 +/- 0.0005 d in the TESS sectors 33 and 34 light curves in addition to the previously reported high-frequency features from sector 7. We discuss the plausible mechanisms that may be responsible for such variability in WR 7, including pulsations, binarity, co-rotating interaction regions (CIRs), and clumpy winds. Given the lack of strong evidence for the presence of a stellar or compact companion, we suggest that WR 7 may pulsate in quasi-coherent modes in addition to wind variability likely caused by CIRs on top of stochastic low-frequency variability. WR 7 is certainly a worthy target for future monitoring in both spectroscopy and photometry to sample both the short (less than or similar to 1 d) and long (greater than or similar to 1000 d) variability time-scales.
KW  - stars: atmospheres
KW  - stars: evolution
KW  - stars: individual: WR 7
KW  - stars: winds
KW  - outflows
KW  - stars: Wolft-Rayet
Y1  - 2022
U6  - https://doi.org/10.1093/mnras/stac1455
SN  - 0035-8711
SN  - 1365-2966
VL  - 514
IS  - 2
SP  - 2269
EP  - 2277
PB  - Oxford University Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Zaragoza-Cardiel, Javier
A1  - Gómez-González, Víctor Mauricio Alfonso
A1  - Mayya, Yalia Divakara
A1  - Ramos-Larios, Gerardo
T1  - Nebular abundance gradient in the Cartwheel galaxy using MUSE data
JF  - Monthly notices of the Royal Astronomical Society
N2  - We here present the results from a detailed analysis of nebular abundances of commonly observed ions in the collisional ring galaxy Cartwheel using the Very Large Telescope (VLT) Multi-Unit Spectroscopic Explorer (MUSE) data set. The analysis includes 221 H II regions in the star-forming ring, in addition to 40 relatively fainter H a-emitting regions in the spokes, disc, and the inner ring. The ionic abundances of He, N, O, and Fe are obtained using the direct method (DM) for 9, 20, 20, and 17 ring H II regions, respectively, where the S++ temperature-sensitive line is detected. For the rest of the regions, including all the nebulae between the inner and the outer ring, we obtained O abundances using the strong-line method (SLM). The ring regions have a median 12 + log O/H = 8.19 +/- 0.15, log N/O = -1.57 +/- 0.09 and log Fe/O = -2.24 +/- 0.09 using the DM. Within the range of O abundances seen in the Cartwheel, the N/O and Fe/O values decrease proportionately with increasing O, suggesting local enrichment of O without corresponding enrichment of primary N and Fe. The O abundances of the disc H II regions obtained using the SLM show a well-defined radial gradient. The mean O abundance of the ring H II regions is lower by similar to 0.1 dex as compared to the extrapolation of the radial gradient. The observed trends suggest the preservation of the pre-collisional abundance gradient, displacement of most of the processed elements to the ring, as predicted by the recent simulation by Renaud et al., and post-collisional infall of metal-poor gas in the ring.
KW  - galaxies: star clusters
KW  - galaxies: individual
KW  - galaxies: abundances
Y1  - 2022
U6  - https://doi.org/10.1093/mnras/stac1423
SN  - 0035-8711
SN  - 1365-2966
VL  - 514
IS  - 2
SP  - 1689
EP  - 1705
PB  - Oxford University Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Meyer, Philipp
A1  - Aghion, Erez
A1  - Kantz, Holger
T1  - Decomposing the effect of anomalous diffusion enables direct calculation of the Hurst exponent and model classification for single random paths
JF  - Journal of physics / Institute of Physics. A, Mathematical, nuclear and general
N2  - Recently, a large number of research teams from around the world collaborated in the so-called 'anomalous diffusion challenge'. Its aim: to develop and compare new techniques for inferring stochastic models from given unknown time series, and estimate the anomalous diffusion exponent in data. We use various numerical methods to directly obtain this exponent using the path increments, and develop a questionnaire for model selection based on feature analysis of a set of known stochastic processes given as candidates. Here, we present the theoretical background of the automated algorithm which we put for these tasks in the diffusion challenge, as a counter to other pure data-driven approaches.
KW  - time-series analysis
KW  - decomposing anomalous diffusion
KW  - anomalous
KW  - diffusion exponent
KW  - process inference
Y1  - 2022
U6  - https://doi.org/10.1088/1751-8121/ac72d4
SN  - 1751-8113
SN  - 1751-8121
VL  - 55
IS  - 27
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Bolotov, Dmitry
A1  - Bolotov, Maxim I.
A1  - Smirnov, Lev A.
A1  - Osipov, Grigory V.
A1  - Pikovsky, Arkady
T1  - Synchronization regimes in an ensemble of phase oscillators coupled through a diffusion field
JF  - Radiophysics and quantum electronics
N2  - We consider an ensemble of identical phase oscillators coupled through a common diffusion field. Using the Ott-Antonsen reduction, we develop dynamical equations for the complex local order parameter and the mean field. The regions of the existence and stability are determined for the totally synchronous, partially synchronous, and asynchronous spatially homogeneous states. A procedure of searching for inhomogeneous states as periodic trajectories of an auxiliary system of the ordinary differential equations is demonstrated. A scenario of emergence of chimera structures from homogeneous synchronous solutions is described.
Y1  - 2022
U6  - https://doi.org/10.1007/s11141-022-10173-4
SN  - 0033-8443
SN  - 1573-9120
VL  - 64
IS  - 10
SP  - 709
EP  - 725
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Morris, Paul J.
A1  - Bohdan, Artem
A1  - Weidl, Martin S.
A1  - Pohl, Martin
T1  - Preacceleration in the Electron Foreshock. I. Electron Acoustic Waves
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - To undergo diffusive shock acceleration, electrons need to be preaccelerated to increase their energies by several orders of magnitude, else their gyroradii will be smaller than the finite width of the shock. In oblique shocks, where the upstream magnetic field orientation is neither parallel nor perpendicular to the shock normal, electrons can escape to the shock upstream, modifying the shock foot to a region called the electron foreshock. To determine the preacceleration in this region, we undertake particle-in-cell simulations of oblique shocks while varying the obliquity and in-plane angles. We show that while the proportion of reflected electrons is negligible for theta (Bn) = 74.degrees 3, it increases to R similar to 5% for theta (Bn) = 30 degrees, and that, via the electron acoustic instability, these electrons power electrostatic waves upstream with energy density proportional to R (0.6) and a wavelength approximate to 2 lambda (se), where lambda (se) is the electron skin length. While the initial reflection mechanism is typically a combination of shock-surfing acceleration and magnetic mirroring, we show that once the electrostatic waves have been generated upstream, they themselves can increase the momenta of upstream electrons parallel to the magnetic field. In less than or similar to 1% of cases, upstream electrons are prematurely turned away from the shock and never injected downstream. In contrast, a similar fraction is rescattered back toward the shock after reflection, reinteracts with the shock with energies much greater than thermal, and crosses into the downstream.
Y1  - 2022
U6  - https://doi.org/10.3847/1538-4357/ac69c7
SN  - 0004-637X
SN  - 1538-4357
VL  - 931
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
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  - 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  - Xu, Pengbo
A1  - Metzler, Ralf
A1  - Wang, Wanli
T1  - Infinite density and relaxation for Levy walks in an external potential
BT  - Hermite polynomial approach
JF  - Physical review
N2  - Levy walks are continuous-time random-walk processes with a spatiotemporal coupling of jump lengths and waiting times. We here apply the Hermite polynomial method to study the behavior of LWs with power-law walking time density for four different cases. First we show that the known result for the infinite density of an unconfined, unbiased LW is consistently recovered. We then derive the asymptotic behavior of the probability density function (PDF) for LWs in a constant force field, and we obtain the corresponding qth-order moments. In a harmonic external potential we derive the relaxation dynamic of the LW. For the case of a Poissonian walking time an exponential relaxation behavior is shown to emerge. Conversely, a power-law decay is obtained when the mean walking time diverges. Finally, we consider the case of an unconfined, unbiased LW with decaying speed v(r ) = v0/./r. When the mean walking time is finite, a universal Gaussian law for the position-PDF of the walker is obtained explicitly.
Y1  - 2022
U6  - https://doi.org/10.1103/PhysRevE.105.044118
SN  - 2470-0045
SN  - 2470-0053
VL  - 105
IS  - 4
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Sparre, Martin
A1  - Whittingham, Joseph
A1  - Damle, Mitali
A1  - Hani, Maan H.
A1  - Richter, Philipp
A1  - Ellison, Sara L.
A1  - Pfrommer, Christoph
A1  - Vogelsberger, Mark
T1  - Gas flows in galaxy mergers
BT  - supersonic turbulence in bridges, accretion from the circumgalactic medium, and metallicity dilution
JF  - Monthly notices of the Royal Astronomical Society
N2  - In major galaxy mergers, the orbits of stars are violently perturbed, and gas is torqued to the centre, diluting the gas metallicity and igniting a starburst. In this paper, we study the gas dynamics in and around merging galaxies using a series of cosmological magnetohydrodynamical zoom-in simulations. We find that the gas bridge connecting the merging galaxies pre-coalescence is dominated by turbulent pressure, with turbulent Mach numbers peaking at values of 1.6-3.3. This implies that bridges are dominated by supersonic turbulence, and are thus ideal candidates for studying the impact of extreme environments on star formation. We also find that gas accreted from the circumgalactic medium (CGM) during the merger significantly contributes (27-51 percent) to the star formation rate (SFR) at the time of coalescence and drives the subsequent reignition of star formation in the merger remnant. Indeed, 19-53 percent of the SFR at z = 0 originates from gas belonging to the CGM prior the merger. Finally, we investigate the origin of the metallicity-diluted gas at the centre of merging galaxies. We show that this gas is rapidly accreted on to the Galactic Centre with a time-scale much shorter than that of normal star-forming galaxies. This explains why coalescing galaxies are not well-captured by the fundamental metallicity relation.
KW  - MHD
KW  - methods: numerical
KW  - galaxies: interactions
KW  - galaxies: starburst
Y1  - 2021
U6  - https://doi.org/10.1093/mnras/stab3171
SN  - 1365-2966
VL  - 509
IS  - 2
SP  - 2720
EP  - 2735
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Vinod, Deepak
A1  - Cherstvy, Andrey G.
A1  - Wang, Wei
A1  - Metzler, Ralf
A1  - Sokolov, Igor M.
T1  - Nonergodicity of reset geometric Brownian motion
JF  - Physical review : E, Statistical, nonlinear and soft matter physics
N2  - We derive. the ensemble-and time-averaged mean-squared displacements (MSD, TAMSD) for Poisson-reset geometric Brownian motion (GBM), in agreement with simulations. We find MSD and TAMSD saturation for frequent resetting, quantify the spread of TAMSDs via the ergodicity-breaking parameter and compute distributions of prices. General MSD-TAMSD nonequivalence proves reset GBM nonergodic.
Y1  - 2022
U6  - https://doi.org/10.1103/PhysRevE.105.L012106
SN  - 2470-0045
SN  - 2470-0053
VL  - 105
IS  - 1
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Schlemm, Tanja
A1  - Feldmann, Johannes
A1  - Winkelmann, Ricarda
A1  - Levermann, Anders
T1  - Stabilizing effect of melange buttressing on the marine ice-cliff instability of the West Antarctic Ice Sheet
JF  - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2  - Owing to global warming and particularly high regional ocean warming, both Thwaites and Pine Island Glaciers in the Amundsen region of the Antarctic Ice Sheet could lose their buttressing ice shelves over time. We analyse the possible consequences using the parallel ice sheet model (PISM), applying a simple cliff-calving parameterization and an ice melange-buttressing model. We find that the instantaneous loss of ice-shelf buttressing, due to enforced ice-shelf melting, initiates grounding-line retreat and triggers marine ice sheet instability (MISI). As a consequence, the grounding line progresses into the interior of the West Antarctic Ice Sheet and leads to a sea level contribution of 0.6 m within 100 a. By subjecting the exposed ice cliffs to cliff calving using our simplified parameterization, we also analyse marine ice cliff instability (MICI). In our simulations it can double or even triple the sea level contribution depending on the only loosely constrained parameter that determines the maximum cliff-calving rate. The speed of MICI depends on this upper bound of the calving rate, which is given by the ice melange buttressing the glacier. However, stabilization of MICI may occur for geometric reasons. Because the embayment geometry changes as MICI advances into the interior of the ice sheet, the upper bound on calving rates is reduced and the progress of MICI is slowed down. Although we cannot claim that our simulations bear relevant quantitative estimates of the effect of ice-melange buttressing on MICI, the mechanism has the potential to stop the instability. Further research is needed to evaluate its role for the past and future evolution of the Antarctic Ice Sheet.
Y1  - 2022
U6  - https://doi.org/10.5194/tc-16-1979-2022
SN  - 1994-0416
SN  - 1994-0424
VL  - 16
IS  - 5
SP  - 1979
EP  - 1996
PB  - Copernicus
CY  - Göttingen
ER  -